Impedance change in enclosure - Tech Stuff Tuesday
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- Опубликовано: 16 окт 2024
- Box rise isn't real, impedance rise is, here is what happens in an enclosure at different power levels and tuning.
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good video, cannot stress enough how vital it is to understand that everything is dynamic. ratings on products are static and used as a baseline or a way to evaluate things on a level playing field. beginners will benefit greatly by understanding this early on imo.
Every driver has a impedance curve every driver impedance curve is affected by enclosure design and placement of enclosure. Videos like this educate keep up the good work
I love this channel.. So many gems being shown with straight to the point speech. Keep it up.
Well.. They do tell ALOT of mistakes to. Seen several videos that's just crap. So I really don't take them too seriously
@@Oystein87 Care to explain?
If I wired at .5 ohm will it run good for 1 ohm stable amp because of box rise
Watching this ..I need to do more research and get some help .this video was awesome really give me motivation to build a spl setup yet I also want it to be able to play music so maybe ports that can be changed .. . Definitely need to talk and get some more knowledge
So, the higher the power, the lower the impedance (at the same frequency). I guess the lowest value of impedance is the DC resistance of the voice coil it self. Is that true? I have a 15" subwoofer dual 2 ohm, wired at 1 ohm. I measured the DC resistance and it is exact 1.0 ohm. I made all the calculations with WinISD for a ported enclosure. I notice that the minimum impedance of the system now is very near to 2.0 ohm... Does this mean that my amplifier, rated 3500W RMS at 1 Ohm will be able to deliver a maximum of its rated power at 2 Ohm (around 2000W RMS)? Or, by increasing the power, the impedance of the speaker at this point will go lower allowing for more power, so 3500W RMS?
Thank you very much. Great explanation!
Really appreciate the videos. SO MUCH changes from frequency to frequency. I kinda already knew about this but this is a reminder why my strapped SQ1200s clip when I know they’re not making 2400 W and other times they’re hitting real hard and making my 12 smelly but not clipping.
Hey i have a question, when the sub in a particular box, lets say it has the highest impedance at 30hz, does that mean the cone is moving less ?
I've heard that at the tuning frequency the cone should be moving the least and the impedance is the lowest at the point.
The highest impedance is the most efficient and will move least at tuning yes. That's generally what will be more efficient too.
I always had higher rms subs running bridged on smaller rms amps and gain was at full tilt, i never knew about gain control??
From my understanding the impedance rises with the resonance essentially canceling the resistance rise out. Is this correct.
Greater efficiency has greater impedance rise, and you typically gain more from efficiency than you do more power.
A vented box will have an impedance curve that has two peaks, one above and one below the resonance frequency. At higher power levels the shape of the curve and the location of the peaks will likely shift a bit due to various factors. I'm guessing that for an SPL design you'd want the higher impedance peak to occur at or near the same frequency that results in the most in-car SPL, at the max voltage your amplifier(s) can provide right? If you use a high-power impedance measurement jig (shouldn't be too difficult to DIY), it might be possible to use that and a free measurement program like REW to track how the impedance curve changes with input voltage to the speaker, and possibly extrapolate those results to amp's max voltage capability.
In terms of SPL design, impedance is the last thing you have to worry about. You'll always get max voltage, max current you won't. If you build for low current (low impedance rise) it won't be as efficient and not nearly as loud.
Hmm. Curious. Given two systems with the same sensitivity rating (e.g. 89dB/2.83V/1M) and difference impedances, all else being equal, the one with the higher impedance is actually the more efficient system, as it takes less power (Voltage*Current) to achieve the same SPL as the lower impedance system. And a lower current draw would mean less voltage drop at your amp's power terminals at peak levels, which will likely improve its peak output voltage capability as well.
But then again, you don't see many, if any, SPL competitors using 8 ohm or higher drivers, LOL. So perhaps I'm missing something in the analysis.
Have you ever taken an impedance curve for your build to see where the peaks lie wrt the measured SPL at or near its peak output capabilities? A DIY high-power impedance measurement jig could assist here. There's a chap (Scott Hinson I believe) that builds jigs for a low fee, but I don't think they're designed for use anywhere near 5kW of power. But maybe all that needs to be done to achieve that target is upgrade the sense resistor to a larger value with a higher power rating...
@@Grommet2007 There is A LOT you're missing. Sensitivity doesn't determine how loud it is, particularly with subs. You'd think theory would dictate that, but I'm doing a video on that soon too. From a design aspect you could have more BL with equal sensitivity which could make a difference. Also, Fs and Vas will have a greater dictation on SPL than sensitivity in the real world application. In SPL applications, impedance is almost exclusively highest at or right around the peak SPL frequency. I demonstrated this in another video. As shown with changing port lengths, impedance went up at the playing frequency (that didn't change) as efficiency went up.
@@EMFAudio Thanks for reply. I know that a subwoofer's REFERENCE sensitivity by itself does not determine how loud a sub is (to be specific, at bass frequencies), but it is one of the factors. A sub with no sensitivity at all will not make any sound. Its Vas, Fs, and Qts and of course how it is actually used (e.g. box type) all contribute to how loud it will be at low frequencies.
Also, Fs and Vas will have a greater dictation on SPL than sensitivity in the real world application." - Vas, Fs and the driver's reference sensitivity are all linked. That statement therefore is not correct. You can't change Vas or Fs without changing the driver's sensitivity in the process. The driver's reference sensitivity is directly proportional to Vas and to the cube of Fs.
" In SPL applications, impedance is almost exclusively highest at or right around the peak SPL frequency." - this was the point I was getting at in my first post.
@@Grommet2007 I think you've misunderstood some things I was saying about sensitivity. In terms of comparison of one driver to another, not one driver to itself with a parts change. Example, actual SPL at 30 hz with a driver that has a 30 hz Fs and a 86 dB sensitivity will be greater than a driver with a 45 hz Fs and a 92 dB sensitivity for example.
It changes because you are moving farther or closer to tuning of the box right? Closer to the tuning frequency the higher the impedance right>?
There are multiple factors but to narrow it down to 1, yes, the closer to tuning the higher it goes.
EMF Audio thanks, easy way for me to remember.
Nice looking subs yellow cones make them look cool it will b nice to get opitions like that for the rest of the subs
That cone is one we were testing but will not be using in production on anything, it isn't what we want. Regardless, that cone alone costs more than our Lowballer line does, the complete sub. It isn't necessary for nearly all of our customers. There is literally about 4 people that will benefit from it.
Uhh got u lol cool vids do thanks
Really wanna see the same tests done when the box is outside in a free field , mic is 1 meter away from the cones to see if at least the software is accurate there.
Hey maybe in the future, we will have lazer scanner to scan the room/vehicle so the software can build a box for that particular room!
I wonder why youtube haven't suggested your channel to me earlier =/.
It still wouldn't be accurate because the ports would be aiming 90 degrees from the subs so there would be some environmental things to consider there still.
@EMF Audio how the amplifier continue delivering 5000 watts with the impedance rise? the amps will increase the voltage and it was designed to deliver 5000 watts at 0.5 ohms so with 4 ohms should deliver less but continue with the same power, those amps are amazing
'Merica's are rated for 12,000 watts @ 1 and 2 ohms, there isn't a 0.5 ohm rating.
@@EMFAudio Thanks men I didn't know those amps
Why weren't the frequencies mentioned? Just peak, below and above, what were those test frequencies?
Frequency isn't relevant to displaying the subject matter. The same thing happens no matter the tuning.
So if woofer is going to use Zobel / Impedance Matching then the value depends on the box size and port length?
More than just box size and port length, but how much pressure it back on the sub during play, the frequency being played, the coil temperature, and even if windows are up or down.
@@EMFAudio Wow, I see, building speaker is harder than I thought. Thank you.
Do sub changes next please. I went from Sundown Xv2 18s to ZV5 18s and gained rise just from the larger magnet and spider pack. I heard neo motors cause the most rise?
The reason it went up was higher efficiency and lower inductance. As a very general rule, the higher the motor force the greater the impedance rise. There are other factors and some exceptions but most times that's what will happen. It's not a coincidence that you might make less power but have great output. Sometimes people focus on the wrong things.
What is the best port calculator to use I used precision ports and the 12volt and they are an inch different...im stuck at the port and not sure which one is right...im using a 4" aero port for a 3.26 c.f. box and precision port calls for 8.21 for the length and the 12volt says 7.21...
Math is math, the reason you'll see a difference is with flared ports. Part of the flare is the length, not all of it.
Brilliant!👍👍👍👍👍
What hardware + software are you using?
Well good to know probably would have tuned my box a little bit higher knowing this... LOL
Interesting, good info!
So realistically with rise you could wire .5 ohms and the amp never actually sees that? Even if the amp isn't rated for half ohm it will always be higher than that playing music? When a manufacturer says half ohm stable does the amp ever see that? Maybe with the subs not playing?
What you should know is a given sub doesn't have a set rise, an enclosure doesn't have a set rise, and the frequency changing also changes that number. It IS possible to play at the impedance you're wired to with no rise and you shouldn't rely on rise for functionality.
@@EMFAudio okay so there is a chance you may get down to wired impedance so it's better to just get an amp that is stable at 1 ohm and makes a ton of power at it's rating rather than wiring down and potentially breaking something.
@@somedude0808 Ideally yes, otherwise it's at your own risk.
My sub in its giant enclosure has a big impedance jump at 28hz when wired for 4ohms. (dual 2ohm)
When wired for 1ohm, it's not as big, but it's still there.
4ohms @28hz is around 24-28ohms (can't remember which exactly) and my amp probably only puts out 200watts there (based on the multimeter reading the voltage)
1ohms @28hz It's around 5ohms, so not as bad, and I can pump full power into it then. But the amp isn't stable at 1ohm while bridged, so I run it at 4ohms as music isn't always playing 28hz, so it's not always going to be 5 ohms.
Video is a bit confusing, I know what it's doing though so I understand it, but seems to be explaining it in a weird way.
You could also overlay an impedance graph showing how the sub models for impedance for a given enclosure, then show SPL/watt/impedance graph and show how it lines up to the model. You should be able to predict what's going to happen before you build the enclosure.
If you watch the video after this one, it shows why modeling is wrong. Electrically speaking it seems to be OK but that is a small sample group. Your impedance rise is a multiplier, that's why its "not as bad". If you do the math, it will be like 2x or 3x rise. If you start with higher numbers, it rises exponentially. You will also find that putting the sub in a different placement will give different impedance, opening windows and doors will be different too. Pressure in the vehicle effects pressure back on the sub which changes impedance. Those have nothing to do with the enclosure but still change the impedance and couldn't be modeled.
EMF Audio Right, I get that, but in this case, the sub I mentioned is in my house, so not as bad as a car. But I'm curious if the car affects the sub at a given frequency (might need to try a handful of different ones) and see if it has a big impact. (Unless you already did that in the other video, which I was going to watch next lol.)
@@JoshM7 the car effects response way more in a car than a home.
So would it be safe to say that it's impossible to ever see the ohm load you are wired too? The minute you add power and the coil begins to move it will generate some form of resistance thus always making resistance higher than where it is at rest. For example if you DMM your sub at rest and your at say 1 ohm exactly, the minute you add power and the coil moves in the magnetic field it would be almost impossible to ever see 1 ohm at any usable frequency for the sub?
You CAN see that impedance, especially below tuning or significantly above tuning. The video before this one explains that a bit.
@@EMFAudio That's why when you are at peak frequency and actual best SPL numbers are usually at the lowest power level too. You will see much less power at peak than below or above peak frequency.
@@EMFAudio If i play a speaker test tone 1000khz and have my Multimeter leads on the speaker to read ohms will it read the impedance rise.? say my speakers are 4ohm and reads more than 4ohm while playing the tone thats the impedance rise yes.? or u just cant figure impedance rise the way i asked.?
so does impedance rise occur in sealed enclosure applications based on box vol/cuft? ive seen alot of people use what i would consider oversized sealed enclosures for the drivers theyre running and i would think that would have and effect on impedance and lower irl power handling.
Impedance is effected by volume in sealed, yes. It's a more gradual curve. It does in fact reduce power handling from a mechanical aspect.
@@EMFAudio thanks for clarifying that.
@@EMFAudio Thank you for the advice. But is the impedance rise in a sealed box bad? I have a 8” kicker Q class that I am designing a box for using Kickers enclosure app. My sealed box I am modeling is twice the size of their recommendation but I am getting much of a quality out on my graphs. But the impedance is spiking at high at 50hz. And rising to 35ohms , about 15 ohms off from theirs
Why does changing the port affect the impedance raising or lowering it?
If you change the port you're changing the tuning. Different tuning puts different pressures back on the sub during play, so impedance changes. That is in combination with it changing because of different frequencies as well.
@@EMFAudio So if I am understanding what your saying correctly, the impedance rise or lowering is due to the environment that subwoofer is interacting with. Is that correct?
@@mattroadfeldt9012 The environment is in addition to. Electrical is what causes it, but the environment changes how much it moves which is electrical in the end. If you change nothing but roll down a window, impedance will change.
@@EMFAudio I am guessing that is why some vehicles are louder when the windows or doors are open however mine always seem to go down by 3-4 db.
@@HashDogg06 Not exactly. Impedance nearly always goes UP when you open a door or window, meaning you'd make less power. For 3-4 dB drop you'd be over doubling your impedance, which is rarely the case, if ever. My Astro used to lose 1 dB from rolling down a window 1 inch. If you opened a door it would lose 7 dB, both doors would lose 12 dB.
I'm getting 2 15s. I was going to get dual 2 wire the subs so the amp would "see" 2 ohms speakers are 2500rms amplifier does 7000rms at 2 ohms. So factor if you factor "impedance rise" I wouldn't be at 2 ohms meaning I might not get the 7000rms... So should I get dual 1 so when I wire them the amp would "see" a 1 ohm load...my amp does 10k at 1 ohm but from what you're saying after "impedance rise" I might be only at 2ohms so instead of 10k I might be seeing 7k. Is that right?
I'm not sure you understood the point of the video. Impedance is dynamic, it could be as low as the subs are wired or higher. That being said, you could see 1 ohm power out of the amp if wired to 1 ohm.
@@tammyforbes2101 Actually, it IS possible to hear a difference. There are cases where it may be a bit louder from power gains at a lower impedance, say from 1 to 2 ohms (this is assuming wired to 1 ohm) where it may be doubling power but the efficiency difference doesn't cover the spread. But even more possible to hear it is in distortion. Wiring below rated impedance can greatly increase distortion. Some amps may be inaudible, others may increase exponentially.
How can I measure my impedance rise without a term lab? Multimeter?
You would need a DMM and ammeter with peak hold or watching both meters at the same time.
Ok so the ohms went from 3. Something to 2. Something with same watts and at 3. Something it did 138 and 137 at 2. In this case frequency was more important than ohms. Also the amp stress less at 3. Ohms and it did betyer numbers so that great it isnt?
The SPL isn't relevant to any of this, but yes it will be louder at the peak frequency, which will have a higher rise. The amp isn't being stressed at all, it's a 14,000 watt amp, and it does it from 1-2 ohms. There is an instance where a higher impedance would be higher stress, the voltage rail could be maxed out before current is, producing less power and maximum limit.
The different ohms wont effect the SPL because it was 50 watts both times. so yeah it was just frequency.
Nice looks like every frequency has a different ohms.
It does, which is why you can't rely on impedance rise.
@@EMFAudio your right thanks EMF you tought me something new every frequency changes the ohms alot it don't just change little amounts but almost 5 ohms on certain frequency.
@@EMFAudio but that's kind of the point of this kind of testing...sweep a range of frequencies and u can see the lowest and know the min rise of the system that way u can know how low u can wire
@@b1782w but that number can change with power too. Ok, so you know how low you can wire for that sub, but not another sub.
@@EMFAudio SO WE DO REBASS SONGS AT FREQUENCY WE WANT :p
i don't know the peak and i was just doing testing with a 100ish w plate amp (@ 8 ohm per sony specs) the box is a 4th, 2.09 cu ft sealed and 5.2 ft ported tuned to 42hz and my results definitely confused me (amp vol was never changed but the wattage was all over the place ) any insight would be appreciated. check comment below this for the data
Freq watts volts amps final ohm box rise
20 142 15.5 9.2 1.68 .68
25 142 16 8.9 1.798 .798
30 68 12.3 5.6 2.196 1.196
35 39 10.7 3.7 2.892 1.892
40 10 7 1.5 4.66 3.66
45 14 5.4 2.6 2.077 1.077
50 8.9 4.7 1.9 2.47 1.47
55 36 12 3 4 3
60 26 13 2 6.5 5.5
wired to 1 ohm subs are american bass hd 12 d1 series-parallel for 1 ohm final load. avg wattage is 53 and avg box rise is 2.114 ... so the question is how do i hit 8 watts 1 min then 5 hz above i'm at 36.. ?? not a very smooth curve.. or does that not matter? testing was done in my living room.
Well, the biggest issue with your testing is you had an 8 ohm amp wired to 1 ohm. That will make it act very weird and I wouldn't use that test data.
@@EMFAudio not even the box rise portion of it? thanks for your time sir
@@notyobiz6207 If the amp is potentially skewing the results, you can't use the results.
how did you get 5k plus from an 8k amp at 4ohms?
It could be wired at 1ohm, but enclosures and ports can change impedance at different frequencies.
So if an amp isn't half ohm stable wouldn't it really depend on your tuning?
Not exactly. This video shows why. ruclips.net/video/APeJRfv5IhA/видео.html This didn't cover the full spectrum of frequencies, in a bigger picture it's possible to achieve DCR. It's not just where you're tuned, it's what you're playing, and how the speaker is responding to the enclosure.
You’d have to measure impedances on every playable frequency and if it’s all over the minimum impedance, you’re “good”. Obviously do it at your own risk
So it no near 0.5 ohms what "it should be"...
Good video
Man that stuff is confusing! Lol
Johnathan Hunter I’m tryna learn too brotha lol
I understand sum but I'm so lost as well. When he says "ohms and impedance " I do understand him
so how does wiring to 0.5 ohm harms the amp, if it always rises above 1ohm ?
Frequencies are dynamic, impedance doesn't stay the same during play. It is possible for impedance to go down as low as how you wired it. So, how does it harm an amp? Well, lower impedance has a higher current on the outputs. If the outputs can't handle the current demand (there is no fusing for that, after all, you shouldn't be doing it, right?) then they fail. There is also the issue of can the power supply handle it? Even if the outputs can handle the current, will the power supply be able to sufficiently keep up with the output demands?
@@EMFAudio ok, thx i see now, 1 more question in related to ohms, i have 4 subs, 3 are 1ohm, and 1 sub is 2 ohms, can i mix and play the 2 ohm sub in with the 3, one ohm subs all wired in series, on strapped amps is that safe?
@@teeone10 Short answer, don't.
@@teeone10 don't do that ever
@@nickriker8336 i didnt, too risky
wat hz are we teating here..???
Doesn't matter, they all do it.
@@EMFAudio ooooo..gotcha..!!!
Enclosure dimensions, and tuning?
If you watch the video, it says all of that. Also, that box is made for those subs in that car.
I've watched this video three times and not once was there any mention of the exact cubes or tune of this enclosure. Only mention was the sub wiring which was half ohm and the impedance fluctuation. I have another question also though, was the shorter port lower or higher tune?
EMF Audio I'm really curious because I have two Deaf Bonce SA3 12'S and I want to have an aero port enclosure built tuned @30hz. I have a 6cube box tuned @35hz currently and its not as low as I'd like.. I've been told that I had an issue with "box rise" which I now know is impedance rise thanks to you videos.. I'm just wondering if I'd be louder with a smaller enclosure instead of a larger one.
@@shaunjay6040 My mistake, this video is the one that has that info. ruclips.net/video/VCYP7CRT5No/видео.html A shorter port is a higher tune when you maintain an enclosure volume.
@@shaunjay6040 6 cu. ft is way too big for ANY pair of 12's. Tuning I can see where you'd want to tune lower but I do believe you would be louder with a much smaller box.
YOU NEVER TOLD THE FREQUENCY!!!
THAT'S BECAUSE THE FREQUENCY DOESN'T MATTER!!!
You busted lol bass boxing
So the real answer is build your setup. Then watch all these videos, then buy a term lab pro setup so you can spend countless hours on research and development so you can adjust and tune your setup for max spl gains. I'm on it.
DAAAAAMN👍👍
So basically correct tuning > increasing power
For SPL specific applications, yes. Changing the enclosure will result in greater gains than simply throwing power at it. For musical application building a more efficient enclosure is better than throwing power at it but if you try to make it peak 1 spot it will lose in another.
ok BUT WHY??
Whey does impedance change?
@@EMFAudio yes. Why is it so different like you shown.
@@jondoe6618 Well, this might offer some insight ruclips.net/video/APeJRfv5IhA/видео.html but aside from that, there are factors with the enclosure and environment. See if that video helps though.
You intentionally do not provide enough information to make a scientific analysis. You are omitting the referenced frequencies, while simultaneously neglecting to continue to measure the impedance rise outside of this narrow range of "frequencies." With a longer port, system tuning has changed; therefore, your test should either quantify based on tuning or include a range that incorporates overlapping frequency ranges.
I don't think you understand the point of the video.
How about instead of making videos and telling everyone how other brands are not being truthful. Instead dont make videos and sell your products cheaper. Time is money. Wonder where else your company is wasting money that could go to being able to drop cost. Also not talking about this video other ones where you tell us how they are not being honest. Also why not compare your products to the good ones that are priced better then yours and sound amazing like nvx and why yours are worth what you are charging.
Do you think we spend tens of thousands of dollars making videos? I myself, already owning the equipment, shoot all the footage, do all the editing, all the uploading, costing $0 to make. Time is the only cost (which wouldn't be cutting the price of thousands of items in half like you're suggesting) and ad revenue actually makes a profit, as big or little as that may be. Aside from that, that would have NOTHING to do with the cost of products. Now, since you bring up cost, perhaps you should watch this ruclips.net/video/QvFBqESCOhg/видео.html to have an understanding of what it costs to operate a business and why things are priced how they are. I think you're confusing "priced better" with "priced cheaper". Why don't I compare our products to some others? Because you'll complain they aren't at the same price point, ours being cheaper. No matter what's being compared it will be seen as an attack, I'd rather show how there is dishonesty and have an honest product.
I do own a business it is a small buisness, nothing on the scale of yours. I guess if your going to make videos i would think comparing the b.s brands i would love to see videos of brands that are good and why your products are better. For me personally probably not anyone else. When i see a brand saying stuff about other brands i assume that there alittle better then what there going against in the video. For instance if i seen kicker saying there better then rockford and showing why i think there on the same level. Your saying yours are better then brands like Rockville. I really am looking for a system no b.s. i have had kicker l5s in a custom made box from d.a.d.s sounded really good. Had jl w3v2s once in a prefab box before i got alittle smarter sounded ok and once in a custom box way better. Then got a 15" nvx sounded crazy good and great price. Right now i have a 12" kicker l7 sitting in my house in custom box and a ct sound at900.1 amp havent hooked it up yet lazy. For me i want to see a good brand show why they are good compaired to a brand that is on the same level. If you have a Porsche dont tell me why your car is better then a ford.
@@getpaid200 The response to every manufacturer comparing their product to another manufacturers product will be "that's rigged" or "that's not a fair comparison" or "you're just hating". Proving why something is misleading educates the consumer. In the case of Rockville the purpose wasn't to say "ours is better than Rockville" but to address what they said. We showed what they said wasn't accurate on their product, and other products. For instance, when they say "no sub will take a tone on rated power" and ours will, why not prove it? Can other subs do it too? Sure. The statement was it's not possible so we showed it was possible.
@@EMFAudio and i do understand you are trying to show the people buying cheaper brands why they should save and drop the cash on a good brand and you might get 2 out of 10. However the people buying those brands are buying them for a reason, money. Your missing out on the people who can drops chunks at a time on a system though. Especially if they always go with a good brand. Just saying maybe make some videos comparing your brand to other good brands and show why yours are better then theres also. What do i know im just an idiot on a cell phone who spends alot of money yearly on car audio.
@@EMFAudio then why even waste the time with the shitty brands seems pointless doing that also. Honestly im not knocking your stuff at all never heard it in person. I had to stop with the fun car audio stuff for about 15 years, raising kids lol. Alot has changed alot of brands i havent heard of. What i have noticed is the new good brands not just you compare there stuff to crap. It would help people like me to see good go against good. Its crazy though the cheap stuff compared to really good stuff from back in the day dollar for dollar can blow that stuff away. Idk im just looking for the best i can get and would love to see videos like those.