The dipole peak is caused by the interaction between the output from the front of the speaker and the back of the speaker. Depending on the width of the baffle it will cancel or reinforce at different frequencies, so you get a pronounced peak in the response where it reinforces (adds), and dips in the response where it cancels. This is most obvious in the first dipole peak at the lowest range of the driver's response, but also has an effect on the frequencies above that. To eliminate it altogether you need to make the baffle wider (at the top and bottom as well) than the lowest frequency you want to get from the driver. That's typically wider than practical. Another way to deal with it is to use separate drivers and vary the width of the baffle where they are located to get the best response. I did that in my main speaker build where I used a 15" woofer for the lowest range on a baffle with deep wings, then used progressively smaller drivers on the baffle as it narrows. The dipole peak problem was responsible for some of difficulty I had, but it was also a hump in the tweeter's response added to it that was the major cause. By shifting the crossover frequency up to 4KHz, it took a lot of the thunder out of the hump and flattened the response to an acceptable smoothness. The 5" midwoofer is happy to play up that high (as confirmed by the distortion measurements) and whenever possible I prefer to cross the tweeter higher to take away the stain of using it at lower frequencies. This may affect the off-axis response of the speaker, but the way I'm using these speakers it would be better if they were more directional.
I noticed that the dipole peak was less when you added the wing to one side (instead of both sides). What if you mount the the drivers on an L shaped baffle?
The only real solution is to operate all drivers under their first dipole peak . Not always easy or cheap to find a driver and crossover setup to accomplis this .
@@einarbk885 "This may affect the off-axis response of the speaker, but the way I'm using these speakers it would be better if they were more directional." From my comment above. As it turns out (because I measured it), the speaker has pretty good off-axis response.
@@einarbk885 several 4” wide range drivers (Fostex 108 Sigma and Mark Audio MAOP 7 come to mind) operate quite nicely up to 10k. Yes above 10k I can see even the best of them needing some help.
John, again this is great stuff. Your practical approach to problem solving is what us novice folks need. Start with knowledge, then application, then tweak with scientific method. Love it!
Interesting observations, off setting the drivers to one side a little on the baffle could help reduce the peaks and dips as well. Which is really what you accomplished when one 4" board was taped to the baffle. In many of my DIY builds I offset the tweeter for that reason.
No, an offset will create two peaks that carry the same diffraction energy out in the room. You should address the real problem, which is diffraction, by rounding the edges of the baffle with a radius of 1-2 inches.
Not normally one to get involved in the technical information regarding crossovers. I found this video a most enlightening and refreshingly honest representation of what to expect when using a wider baffle . Thanks very much for all your efforts. 👍
Using unequal length wings pointing rearward work better for me than a large flat front baffle. I also use a dipole tweeter, or two tweeters with one facing rearward and wired out of phase with the front one.
Always interesting building hifi systems! 7 years ago I built 3-way open baffle speakers. 70x40 cm. 27 cm woofer, 15 cm mid, 10 cm tweeter. Brand SEAS. The tweeter is double: one facing to the front and one facing to the back 180 degrees out of phase to reach dipole radiation in the high frequency area as well. Each driver is driven by its own mono amplifier (so the amplifier contains 6x180 W D-class amplifiers). Crossover is digital using a DSP before amplification. Speakers made of 36 mm solid beech glued panels. Sounds very clear and pure. 🙂
Can ask a question for dummies? If I put two mini guitar amplifiers opposite of each other in a cabinet would that be an asset or a deficit in terms of sound quality? In other words, is there any benefit to having two speakers opposite of each other one facing front and one facing back? THANKS
Experimented with many drivers in ob panels. 8 inch width is not enough. 8-12 inch drivers with whizzer cones and 100db work...range is more like 300-14000.The rearward output needs dampening. Heavy wool works. Then it sounds so good that you want more and you progress and add two sealed box 18 inch 99db woofer driver and two JBL selenium 108db horns. Quadamp, digital x-over, usb interface and suddenly you only want 32bit audiofiles. Soooo goood.
Hi John. To endorse something you noticed. I built some 4 x 2 foot baffles using Eminance 12 Lta. They didn't sound right. Even 1926, 78s sounded like two points of sound. Two low cost DT74/8 tweeters were added. These on paper would work with just a first order crossover and no resistor. They did ! I tried in phase 6 kHz first. After many trials I returned to that. That made no sense. Wide stereo and no lack of treble. I used a Quad 33/303 with tons of bass EQ ( really worked ). I have Magnepans and know Quad ESL. Mine where doing very well. What I got was an octave above and one below. By luck it worked. The idea started with Dynaco A25 I fixed. The 12 lta only had it's mechanical design filtering. Voice quality stood out as good.
Interesting stuff! The only experience that I have with open back speakers is with guitar amps. Of course, that's a whole different thing than high fidelity speaker systems.
I'd love to see you doing this kind of testing again, but instead of extending the front baffle with timber that is parallel with the front baffle, extend it with timber that is perpendicular to the the front baffle. Kinda like a box speaker without the back on it. I've also heard doing this asymmetrically can have benefits.
Have you ever tried spreading out the crossover points to eliminate a bump? If you had an objectionable bump at 4k, and then you made the woofer Low Pass at 3750 and the tweeter High Pass at 4250, that would leave a gap where both are starting their rolloff at 4000, wouldn't it? I would think that would mellow out any bump in that area, but I'm sure it would take a lot of experimentation to get it to flatten out the way you wanted it to.
I tried it and it can work, but it's tricky to get it precise enough (with standard cap and coil values) so that you don't end up with a dip instead of a peak.
I used to install custom car stereos for many years and found that a midwoofer (we called them midbass) drivers worked best (lowest distortion, highest output) crossed over at 130 hz. hope this helps your active x-over build. Also we crossed over the bass considerably less than that (around 100 hz).
@Kev Z A car audio Sound Quality competitor named Jim Becker won the MECA organization's 2015 "World Championship in SQ" in his dual cab Dodge RAM truck using 5.25" Scanspeak Revelator 15M midwoofers and SB Acoustics SB29 silk ring-dome tweeters in sealed dashtop pods aimed relatively on-axis to the driver's seat headrest. A single JL Audio 10W6v3 10" subwoofer in a sealed enclosure placed down in the passenger side footwell. The 5.25" midwoofer's HPF and the subwoofer's LPF were set at 125Hz (I forgot what Type of XO filter, but I believe it was 12dB/octave). The crossover between the midwoofers and tweeters was at 3kHz...not sure of the type or slope. He used a multi-channel ZAPCO car audio DSP to provide the Crossovers, PEQ, and Time Alignment (digital delay) for the system, as well as a pair of small 3" midrange drivers placed high in the rear "C" pillars with low level, delayed Differential "rear fill" (signal is L-R, R-L for each respective rear midrange). These "Differential" Rear Fill drivers were also bandpassed from 300Hz-3kHz. This type of "Differential" rear fill provides for better "room ambiance" as well as a deeper and wider front soundstage. So you're right that a slightly higher HPF on the midwoofers can work extremely well when combined with a good low inductance subwoofer.
I always notch out 5Khz a little. Yes, my speakers are never linear in response but most mammals (specifically humans, cats and dogs) find this frequency tiresome over time. It's the frequency babies (and kittens) cry at. Humans are programmed to feel distress at 5Khz. So notching it out makes music so much more enjoyable.
seems like you need two midwoofers and that offset one side wider baffle had promise to sound best. I wonder about having one mid placed and one with the tweeter on a slightly curved edge plane
Did you ever measure the output of an acoustic guitar? Or a drum kit? My Kef’s LS50 meta measures almost flat. But I don’t care, it sounds great, that’s what’s counts. I like the open baffle speakers though, so keep up the good work!
Can I ask a stupid question for dummies? Can I have a two speakers opposite of each other in an open baffle cabinet? I'll make it simple. I have 2 mini guitar amplifiers and I want to put them in an open back frame with the two speakers from each amp to be opposite of each other meaning one faces the front and one faces the back. Is there any benefit or deficit to this suggestion? THANKS
Convex form will help a lot, and even more so if the edges are rounded with at least 30 mm radius. Countersunk drivers will help reducing the 4 kHz peak. Choice of wood might have an effect but that will not be seen in a measurement like this. ALL mechanical structures have a self resonance point and a lot of harmonics from that point. That is what we call colouration. The cabinets own contribution to the sound so to say. Lowering the amplitude of the resonance point and trying to place it outside the range of the drivers operation is the ticket to get really uncoloured, clean and distortion free sound from a loudspeaker. A loudspeaker cabinet is pretty much like any instrument like a piano, violin or cello. It have it's own sound, and that sound signature needs to be reduced to minimum for true high fidelity reproduction. Many ways to handle that, but it needs to be addressed properly if you want a truly great loudspeaker. Selection of material or wood is one of them.
Is it not because of baffle edge diffraction? 1.would try to put on all edges some round tube or some damping material (left right up down) 2.or put some damping material (carpet) also on 10cm of edges of baffle to reduce middle-high freqencies beaming 3.or try to do rounded buffle + rounded edges (like flat earth)
I love watching and learning about all the different configs of speaker designs, I'm only coming across for the first time of open baffle speakers just now, I am interested but by no means am I a audiophile. If the the open Baffle was curved what response would this have and would it make them more directional to the listeners for that optimal listening position?
I'm looking at using the silverflute 8 ,Dayton audio 2 inch soft dome midrange and a scanspeak ring radiator tweeter in a open baffle and sealed .9 cubic ft build it see and head the difference between the 2 but I'm lost on my crossovers . I'm just in planning right now
I'm a woodworker just getting in to building speakers. Thank you for the this video and information. My comment or question is are most open baffle speakers designed to be installed into walls or ceilings really not making them "open baffle" ?
No they're not designed for wall or ceiling mounting, they're designed to be positioned in a similar way to closed baffle (box) speakers. The rationale for them is that they avoid a boxy sound which is produced by vibrations of cabinet walls and internal reflections exiting through the speaker cones out of phase with the main audio causing peaks and troughs in the response. There are pro's and con's for all baffle designs, personally I like deep closed cabinets with tapering and angled walls.
Hm, I once read that such peak may come from interference in the rear basket of cone speakers and as I made my first open baffle I indeed found a peak at about 4khz. Usually if placed in a more or less closed box one would not notice.
I guess some notch filters can take care of these -but it of course adds complexity to the crossover. My large OBs are smooth enough for me where I dont mind any wiggles because as you said by the seated position, its down enough not to really be an issue :)
Not truly, but they will remove to some extent the issues of peaking and so on, at ONE location. The problem with OB, is if the listener moves to a different location, the reinforcements and cancellations move also.
@@kevintomb True but any room - especially one that is not highly treated, can also have reinforcements and cancellations due to general response and reflections even on a boxed speaker. To a lesser extent but still....
What's the difference between those dB scales ? Why don't you use standard SPL scale..? It's the only part of this I couldn't understand... I don't like that particular Vifa mid/bass driver btw ... try a Peerless equivalent fitted with a phase plug .... it's heaps better
When manufacturers test frequency response with all drivers they are in infinite baffle. Also crossing over mid bass to tweeter @ 4khz is really high Looks like that peak is because it’s not time aligned More problems as you measure vertical off axis will get worse. Having a narrow open baffle with less surface reflection is good but the problem also is a messed up frequency response Needs a lot more correction Dsp or passive more parts Another way to correct is Gr research i Using side wings one long & one short So your increasing size of baffle but still having narrow front baffle Crossover at lower frequency is much better
Very interesting. I am thinking a open baffle speakers response would also greatly react to each room it is placed in. Kind of think a different crossover might be necessary for every time the speaker is relocated. I might be wrong but thinking after one gets the design the best they can with the passive crossover one may end up wanting to use a DAT after that. Am I wrong in assuming Normal high Q woofers work best for open baffle designs? Where the bump flattens out when in an open baffle. And I just subscribed.
The dipole driver response needs to be equalized, as you would for any loudspeaker driver peak. It is not a problem, it is part and parcel of dipole loudspeaker design and can be achieved with two biquad filters. If you want to do a passive design be prepared for subpar/compromised results. The correct design approach is to only use each driver in a frequency range where the dipole response is well behaved both in frequency and directivity. The upper useable limit for a driver is kb=3.6, where k =2pif/c and b is the baffle radius. Beyond this both the directivity and frequency response degrade. The peak is beneficial, if you have proper equalization, as it means you have less cone excursion for the same output as a driver in a seal cabinet. You should not separate drivers by more than ~half wavelength at the crossover frequency and this limit should guide the design, including the number of drivers.
When you added the second baffle extension, the reason the hump & dip became worse is because you added the extensions on opposite sides. Had you added both extensions on the same side that would not have happened. Assymetrical baffles on OB speakers are the designer's best friend.
No, that is not correct. Assymetrical placement will create two peaks instead of one. Lower in amplitude but equal in distributed diffraction energy. If you want to get the total diffraction lower you should round of the edges as much as possible. A U shaped or \_/ with rounded edges would reduce the diffraction the most and still keep the principle of open baffle.
Regarding speaker placement on an open baffle we can consider the distance between the speaker and: The left side of the baffle, The right side of the baffle, And the top of the baffle. Even considering just these three parameter there is an infinite range of different peaks and troughs that can be generated and if you experiment, a placement can be found where peaks and troughs become minimised. Just saying two peaks instead of one just does not make any sense at all. There are many, many different eventualities some of which might be wose but some of which will be better.
@@mikelm222 Yes but I commented on your suggestion to place both extensions on the same side and THAT solution would have created two peaks. The best solution is to have no edges at all by making the edges rounded. +50mm please and 100mm radius is even better.
When determining frequency response in the cross-over region, it's essential to consider the phase response of the filters. For odd order, both H.P. & L.P. filters are the same, but for even order, one is (+) 90, and the other, (--) 90 degrees, which adds to 180 degrees. That's why the polarities are reversed for 2nd order cross-overs. With one 2nd, & one 3rd order, the overall amplitude response will be somewhere in between, which may be good, or bad, depending on the driver characteristics.
That's why I measure. If there are gross phase issues (and it's debatable whether issues that are anything less are audible), it will show in the measurements. And countless hours can be (and is) spent by guys trying to nail down the perfect response, only to have that mostly obliterated when listening in a real room. They'll put in hours fine tuning a crossover and then set the speakers up in what amounts to an echo chamber, where as much as 50% of what they hear is the speaker's interaction with the room in the form of reflections and reverb.
@@IBuildIt Definitely! The ultimate test is "How does it sound?" Theory can point you in the right direction, give you ideas, etc, but as they say, "The proof of the pudding is in the eating."
Duo 2 in vifa full range on vertical open baffle on top, 1meter from wall, Boston ribbon below 8 in sealed mid woofer, 70 hz to 800hz . I need notch filter on midrange drivers? Or just 4k down on spotify equalizer a click?
I guessed 4 khz cos I make open cone speakers (not open baffle) plus boxed woofer. And I tend to get a peak at 4 khz (going by hearing the sweep). 😅 I can address it acustically by cutaways on the cone, and electronically, with a crossover/filter. 😅
you can have something called edge diffraction! that means that when you don't fluch mount them then you have 2 types of edge diffraction. 1 from the speaker's edge and from the edge on the front.
Seems, maybe, kinda, sorta, also, open back speakers might be best tested and tuned in the exact placement in the room for which they are used????? Maybe placing the mic at the listening location????
@@IBuildIt Gated measurement is good, but measuring distance still needs to be around 80% of the distance to the closest reflective surface. 1/2 wave reflection needs to be kept away from the microphone.
@@mkshffr4936 I wouldn't say so. Near field measurement is less problematic with OB compared to closed cabinet since you don't need to compensate for the baffle step. You can use the measurement as it is at least for 200-20000 Hz range. Any measurement below 200 Hz is hard to perform regardless of topology of loudspeaker. The room comes too much into play since near field measurement below 200 Hz don't give a predictable result.
The way to combat this is to make the baffle as slim as possible. Preferably as thin as the driver itself. Open baffle speaker should only be used for mid-range and treble on the same baffle. Use a separate open baffle subwoofer....H frame, or perhaps a ripole.
How does the off axis response look whith such an high xo? Isn't the midrange lp xo just about 1 octave away from the cone brakeup? So only 24db down at brakeup? That better be a controlled brakup for that to work. It all depends on what you can live with I guess. After I got REW going I quickly became a lot more picky since its so easy to get very good results. Like what you see in 2-5k speakers..
A problem with measurements is that while they can point out real issues, they can also make minor ones seem more significant than they are. Our ears / brain are not the same as a measurement mic / software package, so you need to keep things in perspective. The 1/3 octave smoothing is closer to what out ears hear. As for off-axis response, it's excellent. BUT, I have to say that I did make yet another change in the crossover, so the off-axis results are based on the new (and final!) arrangement. Cone breakup on paper cone drivers typically isn't bad, unlike metal cones.
Unless one takes the natural response of the drivers into account when designing a crossover network, one will not get the expected outcome. Adding a 2nd order high-pass to a mid-driver will inevitably result in something more akin to a composite, pseudo fourth-order response due to the existing 2nd order roll-off of the driver itself, for example.
The presentation of Mr. Heisz is very interesting and very well presented BUT as in all that type of presentation you won't ever hear the results ! It's too much ask ! So, what's the point of building speakers if it's not for music listening ? Is it just the decoration for a paddle board ???
How do you propose that you listen to my speakers? Are you stopping by? Even if i made a recording of my speakers, you'd be listening to YOUR speakers or YOUR headphones.
Cone breakup is where the cone becomes non pistonic - that's the definition. Vifa (the manufacturer) recommends the driver's usable range is up to 5KHz. If breakup was happening before 5K, they wouldn't recommend you use it up to that frequency.
@@Poppinwheeeeellllllieeeeez Thanks for the reply. Isn't a sealed box a closed baffle which is an infinite baffle? Yes I see how it acts the same where no sound from the back of the driver can come towards the listener but in addition I was more curious from the point of view that there is no edge to the loudspeaker front to cause diffraction until you reach the corner of the room. It was the merits or not of this I was wondering about as in this video the widerning of the baffle kept altering results. I just can't imagine a baffle any more wide (or 'infinite') than a wall.
@@asx1248 A sealed box needs to have a baffle step compensation (not linear frequency response) so sound and measure linear inside the room. A driver placed in the wall have 1/2 space radiation for all of it's operational frequency range and doesn't need to have a baffle step compensation. At low frequncies (below 50 hz) you still need to compensate for room gain because of radiation limiting walls, flor and ceiling. It's a bit easier to design with an infinite baffle like placing the driver in the wall is, but it also have it's challanges. Infinite baffle problems start at 100 Hz and lower. A loudspeaker cabinet problems start at 500-1000 Hz and lower because of the transition from 1/2 volume radiation pattern into full volume radiation pattern. Depends on the width of the baffle. Needs to be compensated for, and that is what we call the baffle step compensation. The narrower the baffle the higher the transition starts.
Dipole peak ? That was a new name for the edge diffraction that is what you are discussing and investigation here. 4KHz peak is because of drivers edges since they are not countersunk and 700 and 1400 Hz peaks are because of full baffle width diffraction and half width baffle edge diffraction. Round of the edges by a radius 50 mm and see how the peaks get reduced a lot. Like Revel do with their Studio speakers for example.
Google dipole peak and learn the difference between it and edge diffraction. Better to do that before you start talking about it like you understand it.
Solved without a xover filter by side wings of different width and a wedge shaped base. You can't just tape wood for width on as a test. Narrow wedge baffle with wings is measured as the best design. The tweeter needs to have cutouts to minimize the baffle to as little material as possible. You should build some baffle-less speakers. Why bring an elaborate xover into the equation? Just design 2nd or 3 order with high quality foil inductors and film capacitors.
Have you ever tried using the Silver Flute brand of woofers? They're really lovely drivers for their price. I'm not sure that they're ideally suited for high power open baffle implementation, since their Qts isn't particularly high, so there's a risk of overdriving them, but I just think they're such a nice driver that I tend to recommend them when someone is looking for something to play with since they're quite forgiving and sound much better than their price implies.
Two thoughts: Could you use a first order crossover on the tweeter, since it's crossing over higher and then use a third order crossover on the woofer to maintain phase and push the 4k peak down a bit? Or, could you move the crossover point of the woofer down a bit, to something like 3.5k or 3.5k? It sounds like you're happy where it's at, I'm just curious to know if you think either solution would be a bit better?
I tried a bunch of different combinations, including a 1st order on the tweeter and 3rd order on the midwoofer. I can get pretty flat response with a 1st order on both, but with a significant spread between the the two to reduce the peak - 1400Hz on the mid and 2500Hz on the tweeter.
To match two drivers crossing over, they need the same order and roll off type, some types better than others, for example the standard in active XR's is 4th order Butterworth also called Linkwitz crossover which when you mate the LP and HP together at the same crossing point/pole produce a maximally flat amplitude with constant phase. No engineer would mate say for example a 1st order LP with a 2nd order HP because they know you would get poor phase and amplitude alignment.
@@engjds You are wrong. Mixing crossover slopes is done all the time. Sometimes it's done to roll-off a driver quicker to avoid some undesirable stuff (like cone breakup). And sometimes it's done for time alignment. And sometimes it's done because it gives the flattest response.
@@IBuildIt PS: we are talking here about crossovers between one driver and another which should always be the same order, not driver correction which happens independantly.
@@engjds ? Who's "we"? You say that like I butted in. And you are still wrong, whatever way you are trying to say it. In a 2-way speaker, you can have a 1st order on the tweeter and a 2nd order on the woofer. You can have a 3rd order on the tweeter and a 1st order on the woofer. You don't need to match the slope between the drivers at all. You use different slopes to get the best results.
That's a THICK baffle as well. Even with your recess and chamfer on the back, it will act more as a horn from the backside and that response and directivity will be very different compared to the front. Have you measured the response of the isolated Vifa midwoofer only from the back of the baffle to compare it to the front? IMO, you want the response/directivity/dispersion as similar as possible between the front and back. Have you tried mocking up a quick 3/4" thick MDF baffle, or the same 2" thickness but gradually tapering the backside so that the baffle is ~0.5" thick at the side edges? I'm sure that your posted videos lag behind your actual experiments and work, so perhaps you've sorted this and other issues out already.
Putting aside the real possibility that you are blowing the effect way out of proportion and that it has a negligible impact on the total response, you seen to think the outcome of having the back slightly horn-loaded can only be detrimental. Maybe, if it does anything at all, it improves the overall response... I won't know until I put it in the room. That's because, like any other type of speaker, what it puts out from the rear is part of the room response, and not the speaker response we measure. I'm only concerned with the forward response, and I'm completely unconcerned with directivity because of how I'll use these speakers.
Is it possible that speaker manufacturers that produce and sell open baffle speakers are doing it so that they can charge big money to customers without having to build a proper speaker cabinet? All under the pretense that it sounds better than a cabinet? Just wondering ...
Open baffle designs avoid some problems with cabinet colouration but have problems of their own. Usually Q-values are high for drivers suitable for OB designs and mostly high Q means low magnet power and low magnet power usually means low dynamics and a slow and distorted sound. Depends on what your preference are, but I made some designs and it was not my cup of tea. Too slow and muffled. The recoded music didn't hit my ear in a dynamic and musical way. But then my ear are used to Stax earphones and unlimited resolution and low distortion in the bass region. OB can not compete with that kind of sound. Not even remotely close.
No, OBs are made because of the unique benefits they provide in realism. Every approach has strengths and weaknesses. When I first knocked together a simple OB I immediately noticed an amazing "in the room with you" presence. Later we had a professional pianist visiting us and without saying anything to her I put on a piano concerto. She sat there stunned. For classic rock or metal it might not be as noticeable but for classical and unamplified music like folk and jazz it can be far from subtle. The dipole bass can also have advantages in less issues with room modes.
Why not use a simple cap to roll off your frequency before the power amp? A first order roll off is all you will need and you can use high quality caps (I used vcap odam) and it will sound much better. Your sending your entire audio circuit through all of those parts now and it will greatly affect the sound quality. Cap value before the power amp is much better and you just need to know your amps input impedance. As for crossing that high, your now going to beam all those frequency that are narrow than the width of that driver. This is why you want to cross into the tweeter asap. Your measurements are all on axis, but room response is a composite of the horizontal and vertical dispersion, which will have very different frequency responses having a woofer play up that high. 4khz cross is crazy high.
I could set it up both ways and let you listen to it both ways, and not in a million years would you be able to reliably tell the difference between the single cap high pass and the active high pass I'll be making. I'd bet my yearly income on that, I'm so sure. As for beaming and off axis response, they are grossly overblown as important features of a good sounding speaker. And for what I'm using these for, I don't care at all what the off-axis response is, because I'll be listening to these on-axis. With that said, I did measure the off-axis response and it's perfectly acceptable. Guys think that "beaming" is an on or off thing, when it's actually a narrowing of the dispersion. As the midwoofer narrows, the tweeter extends down to fill in the dispersion. Filters aren't on and off either, they have slopes, so the tweeter still has output below the crossover frequency. BTW, it's 5" "woofer". It's perfectly fine to play it up to 4kHz.
@@IBuildIt I'd take that challenge all day. That's like saying I can't decern different caps. Off axis 100% is part of what you are hearing. Your too smart to know that the room doesn't influence the sound. Even the well treated room has room reflections. You hear a sum of on and off axis. This is basics 101. A woofer playing that high also will not be nearly as clean sounding due to the simple physical weight. This is pure physics. Not really debatable.
You'd lose. Big time. And I should say that claiming otherwise blows out your credibility. As for off-axis being 100% of what you hear, maybe in your room. Mine is treated to reduce reflections and greatly improve clarity and overall sound quality. These speakers are meant to REPLACE the reflections you'd otherwise get from your front speakers. Go back and watch my other recent videos going over this speaker project to get the whole story.
Most guys that brag up Open Baffle speakers tend to completely ignore these issues, and pretend they do not exist at all. I brought all this up on a few forums, and got called out as a hater...LMAO
here is my theory about the unwanted peak at 3800hz: too much overlap between woofer and tweeter, caused by crossover. Solution: either you modify crossover cut-off from 12db to 24 db per octave (but watch for increased impedance...) or if you stay at 12 db/octave: cut tweeter at 5000, and woofer at 2500 (trial and error...).
Here is another idea... Sound of speed is 343 m/s, peak at 3800 Hz (cycles/second). 343/3800 = 0,09 meter = 90 mm. Diameter of the tweeter? Countersink the tweeter to get rid of the most of the peak first and then look at what to do with the crossover.
You can't deal with this by using filters to notch out peaks. This is a timing issue. A phasing issue. I know that you know this. Even if you were to filter that peak to be flat it will still sound strange.
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You are wrong, some great drivers even have cone break up above 3Khz, take the Seas Excel (top of the range) that breaks up at around 3Khz, I do not get OB's at all, who wants to listen to music that rolls off below 300Hz, even with subs, in that region they are directional so you need two subs for stereo and the phase alignment will be all over the place between subs and speakers.
And? If that driver breaks up around 3KHz, that means this one does too? Seriously, that's your thought process? Or did you somehow think you heard me say that NO driver breaks up below 3000Hz? Because I did not. I posted the published specs on this driver a few videos ago. It's recommended range is up to 5000Hz. AND, I know what cone breakup looks like when I measure a driver.
@@IBuildIt First, this is a discussion not an argument. Second, the seas Excel is a famous driver with good specifications. Third, good drivers usually have cone break up at higher frequency as far as I know, but willing to be proved otherwise. However the peak you mention I agree is probably not cone break up as its too symetrical, looks more like a resonance thats unassociated).
You don't start a discussion with "you are wrong". You start an argument that way. I know all about Seas drivers and how good they are. I've used them / have them. ALL drivers have cone breakup. It happens when the cone stops behaving like a piston and it happens at different frequencies based on cone diameter and stiffness. I know the peak isn't breakup, since the manufacturer recommended frequency range is up to 5KHz. They wouldn't recommend using the driver in its breakup region OR if it were suffering from a resonance.
@@IBuildIt I never said the peak was breakup, I think I misinterpeted what you said, it sounded something like "It cannot be 5khz because that too low for breakup"-but as in a generality rather than specific to that driver, so if thats what you meant I apologise. BUT you are wrong on the different orders for crossover between drivers however, nothing wrong with that, I make mistakes all the time).
@@IBuildIt come hear my gr research system and I'll guarantee you hear a difference. Absolutely guaranteed. Nx otica with a pair of triple servo subs in a room treated extensively with diffusion and panels much like yours. Absolutely made a huge difference getting the cables off the carpet. Carpet holds static electricity. That is not benign.
Incredible.......if you google "click bait", you would get this video as the best example. Video title : Dirty Little Secret.....First words of narrator : It's NOT actually a Dirty Little Secret.
you guys kill me. it is only as good as your ears. when we were kids we went and collected old tv speKER BACK IN 1970S, THEN WE GOT A BIG SHEET OF 4X8 PLYWOOD AND mounted then on it. then we shoved it into a corner of a room at a 45 degree angle and ther e you have it a super speaker . get out of the garage and be with your wife, if you have one. LOL LOL LOL. taking about oh there is a slight peak in my sound spectrum
Assymetry is not the solution to this problem either. Keeping the diffraction to a minimum by rounding of the edges with at least 50 mm radius will help a lot.
@@mkshffr4936 Actually assymetry is a bad thing since the timing of the cancellation between left and right side will be unequal which you do not want. \_/ shape with rounded edges (+50 mm radius) will give you the least problems.
The dirty little secret is that you have to design them correctly. No speaker has perfectly flat response. It is well known that you want no two edges the same distance from the drivers. After that you have to determine the optimal crossover. Same process as any other speaker really.
The dipole peak is caused by the interaction between the output from the front of the speaker and the back of the speaker. Depending on the width of the baffle it will cancel or reinforce at different frequencies, so you get a pronounced peak in the response where it reinforces (adds), and dips in the response where it cancels. This is most obvious in the first dipole peak at the lowest range of the driver's response, but also has an effect on the frequencies above that.
To eliminate it altogether you need to make the baffle wider (at the top and bottom as well) than the lowest frequency you want to get from the driver. That's typically wider than practical.
Another way to deal with it is to use separate drivers and vary the width of the baffle where they are located to get the best response. I did that in my main speaker build where I used a 15" woofer for the lowest range on a baffle with deep wings, then used progressively smaller drivers on the baffle as it narrows.
The dipole peak problem was responsible for some of difficulty I had, but it was also a hump in the tweeter's response added to it that was the major cause. By shifting the crossover frequency up to 4KHz, it took a lot of the thunder out of the hump and flattened the response to an acceptable smoothness.
The 5" midwoofer is happy to play up that high (as confirmed by the distortion measurements) and whenever possible I prefer to cross the tweeter higher to take away the stain of using it at lower frequencies. This may affect the off-axis response of the speaker, but the way I'm using these speakers it would be better if they were more directional.
I noticed that the dipole peak was less when you added the wing to one side (instead of both sides). What if you mount the the drivers on an L shaped baffle?
The only real solution is to operate all drivers under their first dipole peak . Not always easy or cheap to find a driver and crossover setup to accomplis this .
the problem is that a 5" mid will beam quite a bit with a 4khz crossover, so you get another problem. 4khz = 3.4"
@@einarbk885 "This may affect the off-axis response of the speaker, but the way I'm using these speakers it would be better if they were more directional."
From my comment above.
As it turns out (because I measured it), the speaker has pretty good off-axis response.
@@einarbk885 several 4” wide range drivers (Fostex 108 Sigma and Mark Audio MAOP 7 come to mind) operate quite nicely up to 10k. Yes above 10k I can see even the best of them needing some help.
Theory and empiricism, so rare on youtube.
John, again this is great stuff. Your practical approach to problem solving is what us novice folks need. Start with knowledge, then application, then tweak with scientific method. Love it!
This video left me completely baffled.
Just so long as you are open to it.😉
Subposed to do yer research
... I know nothing about speakers ... or frequencies ... or any of this ... but you're always entertaining
Interesting observations, off setting the drivers to one side a little on the baffle could help reduce the peaks and dips as well. Which is really what you accomplished when one 4" board was taped to the baffle. In many of my DIY builds I offset the tweeter for that reason.
No, an offset will create two peaks that carry the same diffraction energy out in the room. You should address the real problem, which is diffraction, by rounding the edges of the baffle with a radius of 1-2 inches.
A centered driver creates two peaks (maybe even a third), off -center has none! And yes round-overs are a complete given every time.
@@flex-cx9bi
Not normally one to get involved in the technical information regarding crossovers.
I found this video a most enlightening and refreshingly honest representation of what to expect when using a wider baffle .
Thanks very much for all your efforts.
👍
Using unequal length wings pointing rearward work better for me than a large flat front baffle. I also use a dipole tweeter, or two tweeters with one facing rearward and wired out of phase with the front one.
Always interesting building hifi systems! 7 years ago I built 3-way open baffle speakers. 70x40 cm. 27 cm woofer, 15 cm mid, 10 cm tweeter. Brand SEAS. The tweeter is double: one facing to the front and one facing to the back 180 degrees out of phase to reach dipole radiation in the high frequency area as well. Each driver is driven by its own mono amplifier (so the amplifier contains 6x180 W D-class amplifiers). Crossover is digital using a DSP before amplification. Speakers made of 36 mm solid beech glued panels. Sounds very clear and pure. 🙂
Can ask a question for dummies? If I put two mini guitar amplifiers opposite of each other in a cabinet would that be an asset or a deficit in terms of sound quality? In other words, is there any benefit to having two speakers opposite of each other one facing front and one facing back? THANKS
Experimented with many drivers in ob panels. 8 inch width is not enough. 8-12 inch drivers with whizzer cones and 100db work...range is more like 300-14000.The rearward output needs dampening. Heavy wool works.
Then it sounds so good that you want more and you progress and add two sealed box 18 inch 99db woofer driver and two JBL selenium 108db horns. Quadamp, digital x-over, usb interface and suddenly you only want 32bit audiofiles. Soooo goood.
Hi John. To endorse something you noticed. I built some 4 x 2 foot baffles using Eminance 12 Lta. They didn't sound right. Even 1926, 78s sounded like two points of sound. Two low cost DT74/8 tweeters were added. These on paper would work with just a first order crossover and no resistor. They did ! I tried in phase 6 kHz first. After many trials I returned to that. That made no sense. Wide stereo and no lack of treble. I used a Quad 33/303 with tons of bass EQ ( really worked ). I have Magnepans and know Quad ESL. Mine where doing very well. What I got was an octave above and one below. By luck it worked. The idea started with Dynaco A25 I fixed. The 12 lta only had it's mechanical design filtering. Voice quality stood out as good.
Interesting stuff!
The only experience that I have with open back speakers is with guitar amps. Of course, that's a whole different thing than high fidelity speaker systems.
Hello from a fellow Canadian - excellent videos my speaker building friend!
Soon as you said "it's the dipole peak" I hit the "like" button. Yup!!
I'd love to see you doing this kind of testing again, but instead of extending the front baffle with timber that is parallel with the front baffle, extend it with timber that is perpendicular to the the front baffle. Kinda like a box speaker without the back on it. I've also heard doing this asymmetrically can have benefits.
Interesting stuff. Did you try it with assymetrical side wings with roundovers, like Danny Richie on his NX-Tremes / NX-Otika's ?
Nice and informative video. I did not even know I wanted that information, but I am glad I wached it. Thank you John.
Have you ever tried spreading out the crossover points to eliminate a bump? If you had an objectionable bump at 4k, and then you made the woofer Low Pass at 3750 and the tweeter High Pass at 4250, that would leave a gap where both are starting their rolloff at 4000, wouldn't it? I would think that would mellow out any bump in that area, but I'm sure it would take a lot of experimentation to get it to flatten out the way you wanted it to.
I tried it and it can work, but it's tricky to get it precise enough (with standard cap and coil values) so that you don't end up with a dip instead of a peak.
I have no idea what John was talking about but it still sounded pretty good! 🔊🔊
I used to install custom car stereos for many years and found that a midwoofer (we called them midbass) drivers worked best (lowest distortion, highest output) crossed over at 130 hz. hope this helps your active x-over build. Also we crossed over the bass considerably less than that (around 100 hz).
@Kev Z
A car audio Sound Quality competitor named Jim Becker won the MECA organization's 2015 "World Championship in SQ" in his dual cab Dodge RAM truck using 5.25" Scanspeak Revelator 15M midwoofers and SB Acoustics SB29 silk ring-dome tweeters in sealed dashtop pods aimed relatively on-axis to the driver's seat headrest.
A single JL Audio 10W6v3 10" subwoofer in a sealed enclosure placed down in the passenger side footwell.
The 5.25" midwoofer's HPF and the subwoofer's LPF were set at 125Hz (I forgot what Type of XO filter, but I believe it was 12dB/octave). The crossover between the midwoofers and tweeters was at 3kHz...not sure of the type or slope.
He used a multi-channel ZAPCO car audio DSP to provide the Crossovers, PEQ, and Time Alignment (digital delay) for the system, as well as a pair of small 3" midrange drivers placed high in the rear "C" pillars with low level, delayed Differential "rear fill" (signal is L-R, R-L for each respective rear midrange).
These "Differential" Rear Fill drivers were also bandpassed from 300Hz-3kHz. This type of "Differential" rear fill provides for better "room ambiance" as well as a deeper and wider front soundstage.
So you're right that a slightly higher HPF on the midwoofers can work extremely well when combined with a good low inductance subwoofer.
I always notch out 5Khz a little. Yes, my speakers are never linear in response but most mammals (specifically humans, cats and dogs) find this frequency tiresome over time. It's the frequency babies (and kittens) cry at. Humans are programmed to feel distress at 5Khz.
So notching it out makes music so much more enjoyable.
I wonder what would happen if you angled the extension in one direction or the other.
seems like you need two midwoofers and that offset one side wider baffle had promise to sound best.
I wonder about having one mid placed and one with the tweeter on a slightly curved edge plane
Did you ever measure the output of an acoustic guitar? Or a drum kit? My Kef’s LS50 meta measures almost flat. But I don’t care, it sounds great, that’s what’s counts. I like the open baffle speakers though, so keep up the good work!
Can I ask a stupid question for dummies? Can I have a two speakers opposite of each other in an open baffle cabinet? I'll make it simple. I have 2 mini guitar amplifiers and I want to put them in an open back frame with the two speakers from each amp to be opposite of each other meaning one faces the front and one faces the back. Is there any benefit or deficit to this suggestion? THANKS
Would be interesting to see what happens when you use different types of wood and what slightly concave and convex shapes would do.
Convex form will help a lot, and even more so if the edges are rounded with at least 30 mm radius. Countersunk drivers will help reducing the 4 kHz peak.
Choice of wood might have an effect but that will not be seen in a measurement like this. ALL mechanical structures have a self resonance point and a lot of harmonics from that point.
That is what we call colouration. The cabinets own contribution to the sound so to say. Lowering the amplitude of the resonance point and trying to place it outside the range of the drivers operation is the ticket to get really uncoloured, clean and distortion free sound from a loudspeaker.
A loudspeaker cabinet is pretty much like any instrument like a piano, violin or cello. It have it's own sound, and that sound signature needs to be reduced to minimum for true high fidelity reproduction. Many ways to handle that, but it needs to be addressed properly if you want a truly great loudspeaker. Selection of material or wood is one of them.
@@flex-cx9bi thank you
Very appreciated research!
BUT in the first graph you show, of the small baffle, there is NO peak at ca. 3800 Hz, but at ca 2400 Hz!
Is the wood used a factor? Is particle board conducive to accurate frequency response?
Is it not because of baffle edge diffraction?
1.would try to put on all edges some round tube or some damping material (left right up down)
2.or put some damping material (carpet) also on 10cm of edges of baffle to reduce middle-high freqencies beaming
3.or try to do rounded buffle + rounded edges (like flat earth)
I like the spanner hanging on a string for your collet, hehe. Nice touch.
That's a counterweight for the bundled wires going to the gantry. The collet wrench is much smaller.
What does a Tweeter wave guide do in this scenario?
I love watching and learning about all the different configs of speaker designs, I'm only coming across for the first time of open baffle speakers just now, I am interested but by no means am I a audiophile. If the the open Baffle was curved what response would this have and would it make them more directional to the listeners for that optimal listening position?
I'm looking at using the silverflute 8 ,Dayton audio 2 inch soft dome midrange and a scanspeak ring radiator tweeter in a open baffle and sealed .9 cubic ft build it see and head the difference between the 2 but I'm lost on my crossovers . I'm just in planning right now
I use vifa 2in vertically 2 drivers and 5.5 in x5.5 in baffle on top of cabinet. Summed to 8 ohm and the youtube eq cut the 2k slider 3db
okay, but how does it sound in the area you wish to use them? I find measuring doesn't always coincide with how they sound.
I'm a woodworker just getting in to building speakers. Thank you for the this video and information. My comment or question is are most open baffle speakers designed to be installed into walls or ceilings really not making them "open baffle" ?
No they're not designed for wall or ceiling mounting, they're designed to be positioned in a similar way to closed baffle (box) speakers.
The rationale for them is that they avoid a boxy sound which is produced by vibrations of cabinet walls and internal reflections exiting through the speaker cones out of phase with the main audio causing peaks and troughs in the response. There are pro's and con's for all baffle designs, personally I like deep closed cabinets with tapering and angled walls.
Hm, I once read that such peak may come from interference in the rear basket of cone speakers and as I made my first open baffle I indeed found a peak at about 4khz. Usually if placed in a more or less closed box one would not notice.
Hi, i checked ouy ibuild but didn't see any open baffle plans. Is a plan posted?
I guess some notch filters can take care of these -but it of course adds complexity to the crossover. My large OBs are smooth enough for me where I dont mind any wiggles because as you said by the seated position, its down enough not to really be an issue :)
Not truly, but they will remove to some extent the issues of peaking and so on, at ONE location. The problem with OB, is if the listener moves to a different location, the reinforcements and cancellations move also.
@@kevintomb True but any room - especially one that is not highly treated, can also have reinforcements and cancellations due to general response and reflections even on a boxed speaker. To a lesser extent but still....
What's the difference between those dB scales ? Why don't you use standard SPL scale..?
It's the only part of this I couldn't understand... I don't like that particular Vifa mid/bass driver btw ... try a Peerless equivalent fitted with a phase plug .... it's heaps better
It’s not so much a peak at 3800hz as it is a dip on either side. Is my thinking correct on this?
When manufacturers test frequency response with all drivers they are in infinite baffle.
Also crossing over mid bass to tweeter @ 4khz is really high
Looks like that peak is because it’s not time aligned
More problems as you measure vertical off axis will get worse.
Having a narrow open baffle with less surface reflection is good but the problem also is a messed up frequency response
Needs a lot more correction
Dsp or passive more parts
Another way to correct is Gr research i
Using side wings one long & one short
So your increasing size of baffle but still having narrow front baffle
Crossover at lower frequency is much better
Very interesting. I am thinking a open baffle speakers response would also greatly react to each room it is placed in. Kind of think a different crossover might be necessary for every time the speaker is relocated. I might be wrong but thinking after one gets the design the best they can with the passive crossover one may end up wanting to use a DAT after that. Am I wrong in assuming Normal high Q woofers work best for open baffle designs? Where the bump flattens out when in an open baffle. And I just subscribed.
The dipole driver response needs to be equalized, as you would for any loudspeaker driver peak.
It is not a problem, it is part and parcel of dipole loudspeaker design and can be achieved with two biquad filters. If you want to do a passive design be prepared for subpar/compromised results.
The correct design approach is to only use each driver in a frequency range where the dipole response is well behaved both in frequency and directivity. The upper useable limit for a driver is kb=3.6, where k =2pif/c and b is the baffle radius. Beyond this both the directivity and frequency response degrade.
The peak is beneficial, if you have proper equalization, as it means you have less cone excursion for the same output as a driver in a seal cabinet.
You should not separate drivers by more than ~half wavelength at the crossover frequency and this limit should guide the design, including the number of drivers.
When you added the second baffle extension, the reason the hump & dip became worse is because you added the extensions on opposite sides. Had you added both extensions on the same side that would not have happened. Assymetrical baffles on OB speakers are the designer's best friend.
No, that is not correct. Assymetrical placement will create two peaks instead of one. Lower in amplitude but equal in distributed diffraction energy.
If you want to get the total diffraction lower you should round of the edges as much as possible. A U shaped or \_/ with rounded edges would reduce the diffraction the most and still keep the principle of open baffle.
Regarding speaker placement on an open baffle we can consider the distance between the speaker and: The left side of the baffle, The right side of the baffle, And the top of the baffle. Even considering just these three parameter there is an infinite range of different peaks and troughs that can be generated and if you experiment, a placement can be found where peaks and troughs become minimised. Just saying two peaks instead of one just does not make any sense at all. There are many, many different eventualities some of which might be wose but some of which will be better.
@@mikelm222 Yes but I commented on your suggestion to place both extensions on the same side and THAT solution would have created two peaks.
The best solution is to have no edges at all by making the edges rounded. +50mm please and 100mm radius is even better.
@@flex-cx9bi Lowering the amplitude is very much worthwhile. Then take steps such as rounding and or absorption and you can get very smooth results.
When determining frequency response in the cross-over region, it's essential to consider the phase response of the filters. For odd order, both H.P. & L.P. filters are the same, but for even order, one is (+) 90, and the other, (--) 90 degrees, which adds to 180 degrees. That's why the polarities are reversed for 2nd order cross-overs. With one 2nd, & one 3rd order, the overall amplitude response will be somewhere in between, which may be good, or bad, depending on the driver characteristics.
That's why I measure. If there are gross phase issues (and it's debatable whether issues that are anything less are audible), it will show in the measurements.
And countless hours can be (and is) spent by guys trying to nail down the perfect response, only to have that mostly obliterated when listening in a real room. They'll put in hours fine tuning a crossover and then set the speakers up in what amounts to an echo chamber, where as much as 50% of what they hear is the speaker's interaction with the room in the form of reflections and reverb.
@@IBuildIt Definitely! The ultimate test is "How does it sound?" Theory can point you in the right direction, give you ideas, etc, but as they say, "The proof of the pudding is in the eating."
Duo 2 in vifa full range on vertical open baffle on top, 1meter from wall, Boston ribbon below 8 in sealed mid woofer, 70 hz to 800hz . I need notch filter on midrange drivers? Or just 4k down on spotify equalizer a click?
I guessed 4 khz cos I make open cone speakers (not open baffle) plus boxed woofer. And I tend to get a peak at 4 khz (going by hearing the sweep). 😅 I can address it acustically by cutaways on the cone, and electronically, with a crossover/filter. 😅
if you have too high frequencies out of the bass/midrange, the speaker becomes directional in brighter midrange frequencies
you can have something called edge diffraction!
that means that when you don't fluch mount them then you have 2 types of edge diffraction. 1 from the speaker's edge and from the edge on the front.
Seems, maybe, kinda, sorta, also, open back speakers might be best tested and tuned in the exact placement in the room for which they are used????? Maybe placing the mic at the listening location????
Listening distance vs measuring distance. How do you account for room response when measuring speakers?
By using gated measurements. Look that up.
@@IBuildIt Gated measurement is good, but measuring distance still needs to be around 80% of the distance to the closest reflective surface.
1/2 wave reflection needs to be kept away from the microphone.
Close mic'ing is especially problematic with OB as the reflected backwave is a huge part of the total experience.
@@mkshffr4936 I wouldn't say so.
Near field measurement is less problematic with OB compared to closed cabinet since you don't need to compensate for the baffle step. You can use the measurement as it is at least for 200-20000 Hz range.
Any measurement below 200 Hz is hard to perform regardless of topology of loudspeaker. The room comes too much into play since near field measurement below 200 Hz don't give a predictable result.
@@flex-cx9bi My point is that the reflective component in OB is so large that a nearfield measurement misses a lot of what one will actually hear.
The way to combat this is to make the baffle as slim as possible. Preferably as thin as the driver itself. Open baffle speaker should only be used for mid-range and treble on the same baffle. Use a separate open baffle subwoofer....H frame, or perhaps a ripole.
I want to hear about open baffle sub woofers…maybe a 15 inch..
How does the off axis response look whith such an high xo? Isn't the midrange lp xo just about 1 octave away from the cone brakeup? So only 24db down at brakeup? That better be a controlled brakup for that to work. It all depends on what you can live with I guess. After I got REW going I quickly became a lot more picky since its so easy to get very good results. Like what you see in 2-5k speakers..
A problem with measurements is that while they can point out real issues, they can also make minor ones seem more significant than they are. Our ears / brain are not the same as a measurement mic / software package, so you need to keep things in perspective. The 1/3 octave smoothing is closer to what out ears hear.
As for off-axis response, it's excellent. BUT, I have to say that I did make yet another change in the crossover, so the off-axis results are based on the new (and final!) arrangement.
Cone breakup on paper cone drivers typically isn't bad, unlike metal cones.
Driver selection is critical in an OB speaker system.
Unless one takes the natural response of the drivers into account when designing a crossover network, one will not get the expected outcome. Adding a 2nd order high-pass to a mid-driver will inevitably result in something more akin to a composite, pseudo fourth-order response due to the existing 2nd order roll-off of the driver itself, for example.
The presentation of Mr. Heisz is very interesting and very well presented BUT as in all that type of presentation you won't ever hear the results ! It's too much ask ! So, what's the point of building speakers if it's not for music listening ? Is it just the decoration for a paddle board ???
How do you propose that you listen to my speakers? Are you stopping by?
Even if i made a recording of my speakers, you'd be listening to YOUR speakers or YOUR headphones.
Not cone breakup but point in which cone becomes non pistonic perhaps.. cone edge issues causing dips or peaks
Cone breakup is where the cone becomes non pistonic - that's the definition.
Vifa (the manufacturer) recommends the driver's usable range is up to 5KHz. If breakup was happening before 5K, they wouldn't recommend you use it up to that frequency.
What would happen to the response if you mounted drivers straight into the wall?
They used to do this in studios, but it would act as a sealed box speaker, not open baffle.
@@Poppinwheeeeellllllieeeeez Thanks for the reply. Isn't a sealed box a closed baffle which is an infinite baffle? Yes I see how it acts the same where no sound from the back of the driver can come towards the listener but in addition I was more curious from the point of view that there is no edge to the loudspeaker front to cause diffraction until you reach the corner of the room. It was the merits or not of this I was wondering about as in this video the widerning of the baffle kept altering results. I just can't imagine a baffle any more wide (or 'infinite') than a wall.
@@asx1248 A sealed box needs to have a baffle step compensation (not linear frequency response) so sound and measure linear inside the room.
A driver placed in the wall have 1/2 space radiation for all of it's operational frequency range and doesn't need to have a baffle step compensation.
At low frequncies (below 50 hz) you still need to compensate for room gain because of radiation limiting walls, flor and ceiling.
It's a bit easier to design with an infinite baffle like placing the driver in the wall is, but it also have it's challanges.
Infinite baffle problems start at 100 Hz and lower.
A loudspeaker cabinet problems start at 500-1000 Hz and lower because of the transition from 1/2 volume radiation pattern into full volume radiation pattern.
Depends on the width of the baffle. Needs to be compensated for, and that is what we call the baffle step compensation.
The narrower the baffle the higher the transition starts.
@@flex-cx9bi great explanation.. Ive heard the term baffle step for years and I think now, I understand what it is!! Thanks.
Having no understanding of this.. I find it all... Baffling. I'll see myself out...
Don't forget your coat 😂
Nice job thanks for the video
Dipole peak ?
That was a new name for the edge diffraction that is what you are discussing and investigation here. 4KHz peak is because of drivers edges since they are not countersunk and 700 and 1400 Hz peaks are because of full baffle width diffraction and half width baffle edge diffraction.
Round of the edges by a radius 50 mm and see how the peaks get reduced a lot.
Like Revel do with their Studio speakers for example.
Google dipole peak and learn the difference between it and edge diffraction.
Better to do that before you start talking about it like you understand it.
@@IBuildIt There is now difference.
Different names of the same problem.
It isn't the same. One is based on the radiation pattern (diffraction) and the other is based on cancellation.
Like I said, look it up.
@@flex-cx9bi
Solved without a xover filter by side wings of different width and a wedge shaped base. You can't just tape wood for width on as a test. Narrow wedge baffle with wings is measured as the best design. The tweeter needs to have cutouts to minimize the baffle to as little material as possible. You should build some baffle-less speakers. Why bring an elaborate xover into the equation? Just design 2nd or 3 order with high quality foil inductors and film capacitors.
Have you ever tried using the Silver Flute brand of woofers? They're really lovely drivers for their price. I'm not sure that they're ideally suited for high power open baffle implementation, since their Qts isn't particularly high, so there's a risk of overdriving them, but I just think they're such a nice driver that I tend to recommend them when someone is looking for something to play with since they're quite forgiving and sound much better than their price implies.
Two thoughts: Could you use a first order crossover on the tweeter, since it's crossing over higher and then use a third order crossover on the woofer to maintain phase and push the 4k peak down a bit? Or, could you move the crossover point of the woofer down a bit, to something like 3.5k or 3.5k? It sounds like you're happy where it's at, I'm just curious to know if you think either solution would be a bit better?
I tried a bunch of different combinations, including a 1st order on the tweeter and 3rd order on the midwoofer. I can get pretty flat response with a 1st order on both, but with a significant spread between the the two to reduce the peak - 1400Hz on the mid and 2500Hz on the tweeter.
To match two drivers crossing over, they need the same order and roll off type, some types better than others, for example the standard in active XR's is 4th order Butterworth also called Linkwitz crossover which when you mate the LP and HP together at the same crossing point/pole produce a maximally flat amplitude with constant phase. No engineer would mate say for example a 1st order LP with a 2nd order HP because they know you would get poor phase and amplitude alignment.
@@engjds You are wrong. Mixing crossover slopes is done all the time. Sometimes it's done to roll-off a driver quicker to avoid some undesirable stuff (like cone breakup). And sometimes it's done for time alignment. And sometimes it's done because it gives the flattest response.
@@IBuildIt PS: we are talking here about crossovers between one driver and another which should always be the same order, not driver correction which happens independantly.
@@engjds ?
Who's "we"? You say that like I butted in.
And you are still wrong, whatever way you are trying to say it.
In a 2-way speaker, you can have a 1st order on the tweeter and a 2nd order on the woofer.
You can have a 3rd order on the tweeter and a 1st order on the woofer.
You don't need to match the slope between the drivers at all. You use different slopes to get the best results.
At first I read the title as Open WAFFLE Speakers. I watched the video anyway.😏
Open waffles on my cooking channel, coming soon.
@@IBuildIt definately "butter worth"...
Hmmm... maybe I should try waffle pattern for my next OB project. 😊
Yes cone break-up at 1500hz, that is correct.
That's a THICK baffle as well. Even with your recess and chamfer on the back, it will act more as a horn from the backside and that response and directivity will be very different compared to the front. Have you measured the response of the isolated Vifa midwoofer only from the back of the baffle to compare it to the front?
IMO, you want the response/directivity/dispersion as similar as possible between the front and back.
Have you tried mocking up a quick 3/4" thick MDF baffle, or the same 2" thickness but gradually tapering the backside so that the baffle is ~0.5" thick at the side edges?
I'm sure that your posted videos lag behind your actual experiments and work, so perhaps you've sorted this and other issues out already.
Putting aside the real possibility that you are blowing the effect way out of proportion and that it has a negligible impact on the total response, you seen to think the outcome of having the back slightly horn-loaded can only be detrimental. Maybe, if it does anything at all, it improves the overall response... I won't know until I put it in the room.
That's because, like any other type of speaker, what it puts out from the rear is part of the room response, and not the speaker response we measure.
I'm only concerned with the forward response, and I'm completely unconcerned with directivity because of how I'll use these speakers.
@@IBuildIt
So these are going to be used as nearfield loudspeakers?
Is it possible that speaker manufacturers that produce and sell open baffle speakers are doing it so that they can charge big money to customers without having to build a proper speaker cabinet? All under the pretense that it sounds better than a cabinet? Just wondering ...
Open baffle designs avoid some problems with cabinet colouration but have problems of their own. Usually Q-values are high for drivers suitable for OB designs and mostly high Q means low magnet power and low magnet power usually means low dynamics and a slow and distorted sound.
Depends on what your preference are, but I made some designs and it was not my cup of tea. Too slow and muffled. The recoded music didn't hit my ear in a dynamic and musical way.
But then my ear are used to Stax earphones and unlimited resolution and low distortion in the bass region. OB can not compete with that kind of sound. Not even remotely close.
No, OBs are made because of the unique benefits they provide in realism. Every approach has strengths and weaknesses. When I first knocked together a simple OB I immediately noticed an amazing "in the room with you" presence. Later we had a professional pianist visiting us and without saying anything to her I put on a piano concerto. She sat there stunned. For classic rock or metal it might not be as noticeable but for classical and unamplified music like folk and jazz it can be far from subtle. The dipole bass can also have advantages in less issues with room modes.
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Why not use a simple cap to roll off your frequency before the power amp? A first order roll off is all you will need and you can use high quality caps (I used vcap odam) and it will sound much better. Your sending your entire audio circuit through all of those parts now and it will greatly affect the sound quality. Cap value before the power amp is much better and you just need to know your amps input impedance.
As for crossing that high, your now going to beam all those frequency that are narrow than the width of that driver. This is why you want to cross into the tweeter asap.
Your measurements are all on axis, but room response is a composite of the horizontal and vertical dispersion, which will have very different frequency responses having a woofer play up that high. 4khz cross is crazy high.
I could set it up both ways and let you listen to it both ways, and not in a million years would you be able to reliably tell the difference between the single cap high pass and the active high pass I'll be making. I'd bet my yearly income on that, I'm so sure.
As for beaming and off axis response, they are grossly overblown as important features of a good sounding speaker. And for what I'm using these for, I don't care at all what the off-axis response is, because I'll be listening to these on-axis.
With that said, I did measure the off-axis response and it's perfectly acceptable.
Guys think that "beaming" is an on or off thing, when it's actually a narrowing of the dispersion. As the midwoofer narrows, the tweeter extends down to fill in the dispersion. Filters aren't on and off either, they have slopes, so the tweeter still has output below the crossover frequency.
BTW, it's 5" "woofer". It's perfectly fine to play it up to 4kHz.
@@IBuildIt I'd take that challenge all day. That's like saying I can't decern different caps.
Off axis 100% is part of what you are hearing. Your too smart to know that the room doesn't influence the sound. Even the well treated room has room reflections. You hear a sum of on and off axis. This is basics 101.
A woofer playing that high also will not be nearly as clean sounding due to the simple physical weight. This is pure physics. Not really debatable.
You'd lose. Big time. And I should say that claiming otherwise blows out your credibility.
As for off-axis being 100% of what you hear, maybe in your room. Mine is treated to reduce reflections and greatly improve clarity and overall sound quality.
These speakers are meant to REPLACE the reflections you'd otherwise get from your front speakers. Go back and watch my other recent videos going over this speaker project to get the whole story.
You don't want symmetrical panels. That why 3 panels is best of all samples.
Music is not repetitions forever, by the time the reflected signal gets to your ears, the front of the signal has changed
Panel too wide.. need a filter to compensate for step baffle loss.
Most guys that brag up Open Baffle speakers tend to completely ignore these issues, and pretend they do not exist at all. I brought all this up on a few forums, and got called out as a hater...LMAO
Your DAWG is haunted !
here is my theory about the unwanted peak at 3800hz: too much overlap between woofer and tweeter, caused by crossover. Solution: either you modify crossover cut-off from 12db to 24 db per octave (but watch for increased impedance...) or if you stay at 12 db/octave: cut tweeter at 5000, and woofer at 2500 (trial and error...).
Here is another idea...
Sound of speed is 343 m/s, peak at 3800 Hz (cycles/second). 343/3800 = 0,09 meter = 90 mm. Diameter of the tweeter?
Countersink the tweeter to get rid of the most of the peak first and then look at what to do with the crossover.
You can't deal with this by using filters to notch out peaks. This is a timing issue. A phasing issue. I know that you know this. Even if you were to filter that peak to be flat it will still sound strange.
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You are wrong, some great drivers even have cone break up above 3Khz, take the Seas Excel (top of the range) that breaks up at around 3Khz, I do not get OB's at all, who wants to listen to music that rolls off below 300Hz, even with subs, in that region they are directional so you need two subs for stereo and the phase alignment will be all over the place between subs and speakers.
And? If that driver breaks up around 3KHz, that means this one does too? Seriously, that's your thought process?
Or did you somehow think you heard me say that NO driver breaks up below 3000Hz? Because I did not.
I posted the published specs on this driver a few videos ago. It's recommended range is up to 5000Hz. AND, I know what cone breakup looks like when I measure a driver.
@@IBuildIt First, this is a discussion not an argument.
Second, the seas Excel is a famous driver with good specifications.
Third, good drivers usually have cone break up at higher frequency as far as I know, but willing to be proved otherwise.
However the peak you mention I agree is probably not cone break up as its too symetrical, looks more like a resonance thats unassociated).
You don't start a discussion with "you are wrong". You start an argument that way.
I know all about Seas drivers and how good they are. I've used them / have them.
ALL drivers have cone breakup. It happens when the cone stops behaving like a piston and it happens at different frequencies based on cone diameter and stiffness.
I know the peak isn't breakup, since the manufacturer recommended frequency range is up to 5KHz. They wouldn't recommend using the driver in its breakup region OR if it were suffering from a resonance.
@@IBuildIt I never said the peak was breakup, I think I misinterpeted what you said, it sounded something like "It cannot be 5khz because that too low for breakup"-but as in a generality rather than specific to that driver, so if thats what you meant I apologise. BUT you are wrong on the different orders for crossover between drivers however, nothing wrong with that, I make mistakes all the time).
Open baffles are fine as long as they are larger than 20 meters by 20 meters.
Nonsense. Much smaller baffles work just fine when done properly.
GR Research can teach you how to do open baffle correctly.
And about cable lifters.
@@IBuildIt So getting the cables off the ground offer no improvements. I'm asking for a friend.
Very cheesey comment. I think you need some fancy resistors to clear your vocals up.
GR Research answered the question (see Tech talk 14, for example)
@@IBuildIt come hear my gr research system and I'll guarantee you hear a difference. Absolutely guaranteed. Nx otica with a pair of triple servo subs in a room treated extensively with diffusion and panels much like yours. Absolutely made a huge difference getting the cables off the carpet.
Carpet holds static electricity. That is not benign.
Uh oh, time for dsp...
I don't try to impress others with measurements.
I build a setup that sounds good to ME.
What others think, is none of my business.
Incredible.......if you google "click bait", you would get this video as the best example. Video title : Dirty Little Secret.....First words of narrator : It's NOT actually a Dirty Little Secret.
I honestly don't understand what you are trying to say
You should shape your baffles like a guitar 🎸
Your measuring your room, not your speaker.
100$ hifiman 400se headphone gets you open baffle experience before going this route.
you guys kill me. it is only as good as your ears. when we were kids we went and collected old tv speKER BACK IN 1970S, THEN WE GOT A BIG SHEET OF 4X8 PLYWOOD AND mounted then on it. then we shoved it into a corner of a room at a 45 degree angle and ther e you have it a super speaker . get out of the garage and be with your wife, if you have one. LOL LOL LOL. taking about oh there is a slight peak in my sound spectrum
Symetri is not good.
Assymetry is not the solution to this problem either. Keeping the diffraction to a minimum by rounding of the edges with at least 50 mm radius will help a lot.
@@flex-cx9bi Or better yet both.
@@mkshffr4936 Actually assymetry is a bad thing since the timing of the cancellation between left and right side will be unequal which you do not want.
\_/ shape with rounded edges (+50 mm radius) will give you the least problems.
Clickbait.
The dirty little secret is that you have to design them correctly. No speaker has perfectly flat response. It is well known that you want no two edges the same distance from the drivers. After that you have to determine the optimal crossover. Same process as any other speaker really.
John tubeyou gas thrown up yr videos into my feed ... you talk a good talk BUT when are you going to actually make a video with SOUND ....
Everyone's hearing is different, what sounds good to me might sound like shit to someone else.