Case in point . My next amplifier build , the power amp will be two 6v6 wired in SRPP , thus no dc bias , thus no dc core saturation in the primary coil...
I am building a replica of an old Vox amp. Its original OT had an 8K input impedance with 8 & 15 Om secondary taps. The amp was originally rated as a 10W amp, but anecdotally owners of originals and its tube compliment mean it probably pushes more like 18W when driven hard. It had 1 x 12AX7 as pre-amp and tremolo, 1 x 12AU7 for second gain stage, (cathode coupled), 1 x 12AU7 for reverb drive and recovery, 1 x 12AU7 for phase inverter, 2 x EL84 output tubes cathode biased in push/pull and 1 x EZ81 rectifier. The PT was 300-0-300V giving a DC output design V of 390V before the first dropping resistor/filter stage. The B+ was around 300V. There are no specs I can find for the original English made Drake OT which had serial nos 352-98 or 352-93. A similar OT available on the market today with similar impedance are only rated for 10 or 15W. Likely the original was only rated at 10W as owners report them running hot and they produce very compressed and nice distortion when driven with good hi end freq output. In guitar amps having an undersized core and exceeding the power rating was a very common reality. Pushing the transformer over its limits can give a nice saturated tonal quality to the sound that so many people prefer. The original OT was wound on an EI-075 lamination (35 UK style) with a 1" stack height. It looks as though it had interleaved Prim-Sec but I don't know how many. Probably on 2-2 or 2-3 given the bobbin size and stack height. My assumption therefore is that the OT might have been rated at 10W. Is it possible to get 15W rating on such a small footprint? Merc Mag make what they call an OT for this vintage amp and claim a 15W rating but this is arbitrary depending how it was measured, at what freq and into what type of load etc, so it is hard to tell. Despite running hot they seem to last despite being small for what the amp puts out when driven hard. Hammond do a 1760E for a Fender which looks like its on the same lamination. Its 8.5K prim though ion 8 and 16 Ohm Sec which should be OK with my project as A-A Imp is 8K for two EL84's in PP config. So 8.5L is very close. Is it likely something made circa 64 would have had interleaved windings between Pri and Sec. This would have added cost and inter winding capacitance would increase, but this a trade off between the reduction in eddy currents. Have I got that right. I could go up one size lamination to an EI-87 (147 UK) which is marginally bigger but allows for more intricate winding topology. However I don't want to end up with something that changes the tonal characteristics of the original. The MM OT supposedly made to suit the amp is really expensive at $212 US. Whilst it appears MM are generally more expensive than competitors it may be that some of this cost is related to the time it takes to do the interleaved windings and how many there are. The more I study the theory the harder it seams to hone in on a spec to have a OT wound to suit my project.
The output transformer on my Laney VC 30 combo creates the best harmonics i have ever heard at volume 7or 8 or higher but is renown for blowing the OT at volume 10 after some time ! The power tubes breakup with awesome aggressive slapping style but retains the articulate chord tones as you pick less forcefully ! It is great for rythem and blues ! I have other tube amps but the power tubes do not breakup like the Laney VC 30 ! The OT transformer must be the key to this tone when pushed at high volumes ! The strident highs on the amp get clipped down to a perfect timber when pushed to breakup the power tubes ! The amp has no flubby low notes but strident tight lows with authority ! I think now the OT transformer is nearly a perfect match for the 70/80 Celestion speaker and the 4- el84 power tubes !
I have not found complete information about choosing the correct transformer. The output in watts also is a factor in Plate load.There needs to be a good calculator with Tube model ,watts max, and Plate voltage. All those factors need to be considered before you divide the tube load by your impedance ratio. Plate load goes down with smaller maximum power output in watt. but goes up with higher voltages applied to Plate. Google the G.E. 6l6 gc and the Tung sol 6l6 gc data sheets. I believe screen voltage also affects plate load as well. Please let me know if there is a more complete way to calculate Plate load for output transformer primary load.
Rob, I love the discussion showing design choice of power, distortion, player style and 3rd harmonic. I've spent a considerable amount of time understanding OPT physical and circuit design (even built a cnc coil winder). I'll have to keep this tradeoff you've presented here in mind during my OPT research. Thanks. Craig
Great video, thank you! I have an output transformer question you might be able to help answer. Last summer I built a Mojotone black panel Princeton reverb from the kit they sell. I made a grievous error when soldering the output tubes by mis wiring one of the output wires from the phase inverter to one of the unused pins on one of the power tubes. The other power tube was wired correctly. So, one power tube was getting half phase signal and the other power tube was getting no input signal at all. I imagine the output transformer did not like this at all… not knowing what I had done, I played the amp for a few days, thinking it sounded very wrong but it might just need breaking in, lol. When the amp started cutting and out I stopped playing it, took the head out and found my mistake. So, now the amp works, sounds pretty good actually, but, and here is the issue, when I play a chord or note and let it ring out, as the note fades, there is this grungy distortion that slowly goes up in volume. It’s really bad on big jazz chords like a major 9 chord. Once again, distortion goes up as the note volume fades… after watching your video I’m am wondering if I damaged the output transformer but didn’t totally fry it… any thoughts on this? Thanks!
Thanks very much for your comment, Omar. Chances are you have not damaged your output transformer if I understand your wiring error correctly, but a DC resistance test of both halves of the primary compared against the published spec would confirm this. You may have another wiring error to chase down, though. Tube amps are quite forgiving; component-damaging incidents are rarely subtle :)
@@robertjamesrobson2907 thanks for your input, I really appreciate it. I’ll look elsewhere to solve this issue, but for now I’m stumped, lol. It’s like the softer I play the more distorted it is… weird
I am an amateur electronic enthusiast and have a million questions, so please indulge me... 4:35 The power supply of a tube amp is a voltage supply, right? If W = V * I and I = V / R (or in this case, Z) and voltage is constant across changes in load and current, increasing the load at the same voltage would only decrease current and therefore power... so why does the power vs impedance graph have a hump instead of being a downward slope? Most tube spec sheets I find generally show maximum plate power and maximum cathode current... how can I find maximum plate current? Also, even if even order distortion is cancelled out in a push-pull design, one would want the load on the tubes to as low as possible (which is why I would want to know the max plate current) as to minimize odd-order distortion harmonics, right? Finally, you covered how load impedance affects how the tubes distort... what about transformer distortion itself? I have heard that that sound is desirable in guitar amps, so would one would want a transformer as small as possible as to saturate as much as possible without blowing up? If the sound is undesirable, why aren't we using high powered toroidal transformers? Thanks!!!
When reversing the output transformer plates wires the power tubes will cause oscillating & squealing, any reasons why? Also the output transformer limits the headroom the max peak AC waveform because SRV tech would swap his output transformers with dual showman output transformers or use the 50s tweed twin output transformers because it had higher headroom Cesar Diaz claimed the tweed output transformers were different for some reason
Excellent! So what makes an old lay down Drake sound so good? When classictones makes a vintage style OT what about it is impacting the sound (if it is)?
Really informative video. Superb interweaving of engineering, experience and application. Presented with style. Any guidance on wattage ratings when matching output tubes, output transformer and speaker? Especially with 'unidentified' output transformers?
Thanks very much for your kind comments, Clive. To answer your question about wattage ratings as succinctly as I can, when faced with an unknown output transformer, you can rely on the fact that manufacturers rarely stray far from norms. This means you can be fairly certain that an unknown transformer will have a similar wattage rating to others with similar core dimensions (and, by extension, weight). Online transformer catalogs provide useful access to ballpark power handling info. Just keep in mind that you can't compare single-ended with push-pull transformers this way: their constructions are different Also, some designers like their output transformers to be undersized so their cores saturate more easily (which coincidentally saves money and weight) , but for DIY projects or any application where reliability is important, there's no convincing argument for going too small IMHO. The same goes for total speaker power ratings, which must meet or exceed the amp's output if they're to last. I say 'total' because individual driver power ratings can be added of course. Incidentally, this is the sole reason larger classic amps had multiple speakers - to handle the power. It certainly wasn't done for dispersion, cost or weight reasons. i hope this answers your question!
@@q.b.amplification8056 that's really helpful info...thanks. Funny how many cost saving efforts of the past morph into the stuff of engineering legend.
@@clivebarrell6448 You've hit the nail on the head, Clive. The rarely-met challenge is to separate the beneficial flukes and genuinely effective engineering choices of old from the irrelevant and obsolete elements that continue to get cloned into guitar amp designs, feeding a cycle of myth and misunderstanding.
Great one. Thank you sir. I do love orange 5 section transformers. You have any particular faves? Happen to know the main differences (if any are main) between drake and dagnall?
Wow, thank you, Rob, great analogies too. I got here while looking for a way to play the audio from my PC on a guitar amplifier. I'm fairly sure it is an issue of impedance matching. I'm trying to play my PC's audio out (stereo headset output jack) through my guitar amp (mono input jack). I know -- I think I know -- that my PC can power 8 ohm speakers. I've heard that the input to guitar amps is Hi-Z (high impedance). So what kind of transformer do I need in order to play my PC's sound through my guitar amp? And where would I get that transformer?
Hi Ron - thanks very much for your comments. Audio transformers are generally used only where there is a need to deliver maximum signal power from the source to the load, whether this be in a tube output stage or in certain types of microphone inputs. This isn't the case with what you're wanting to do, as the low impedance output from your PC will have no difficulty driving the high-impedance input of your guitar amp. A direct connection should work fine. Your only concerns are signal voltage level and frequency response. You'll want to adjust the output level of your PC and the input gain of your amp to obtain the best balance between headroom and noise. I'd suggest starting with the amp's input gain at a low setting, then turning up the PC's output level gradually. As for frequency response, guitar amps are far from flat, so recorded music never sounds very good through them. You may need to start with the mid control up full (if there is one), and the bass and treble controls turned down, then adjust for best compromise. Short answer / good news: you don't need a transformer: just a stereo 3.5mm to mono 1/4" cable, some fiddling, and the willingness to accept less-than-stellar sound.
@@q.b.amplification8056 It works! Thanks, Rob. I had an old Acer laptop running XP (neither are really relevant). It has a separate jack for microphone and another for audio out. Plugging in an adapter somewhat like you described, a 3.5 mm mono plug with a 1/4 inch mono output, and a guitar cable between that and the guitar amp's input did the trick. As you recommended, I turned the LOW and HIGH knobs to 1 (of 10), and left the MID knob at 5 (of 10), and started with the amp volume LEVEL at 1, all this on the CLEAN channel. I found the best mix when the laptop's output was at 50%. A Crate DFX-30 was loud at a LEVEL setting of 3; a Crate DFX-65, at 1. The sound is stereo. I don't know how this will work with other computers (jack for headset with mic) and with different amps, but at least nothing bricks. Thanks again.
Man, this video is really enlightening. My tech thinks it’s a good idea to change the output transformer on a reissue jtm 45. Any thoughts? Thanks again. Cheers!🍷🤘
Thank you very much for this excellent tutorial. Loved it. Question: What makes a given transformer "hi-def" or "hi-fi"? As you know, these phrases are well used by people as the transformers to buy. How are these transformers different?
Thanks very much, Christopher. The terms you mentioned don't have specific technical definitions - they're really just used to sell products. The engineers at McIntosh were designing beautiful transformers half a century ago - the state-of-the-art has moved forward only a relatively tiny amount since then. What constitutes hi-def and hi-fi is very subjective, although attempts have been made over the years to define hi-fi as a certain frequency range, flatness, and maximum distortion level. If you have the luxury of experimentation, the fidelity one can extract from surplus and/or modest components can be remarkable.
I have a question out of curiosity; Does the output transformer if it's going bad will it affect the amps overdrive?. In other words will the sustain begin to diminish?
Is it worth changing over power wires black / white on fender blues junior to get 240v. If I got a 110 amp could I just add 240 v transformer or ix that dangerous?
Great video. One question from someone for whom this is new: does this mean that a relatively colder biased amp (thus lower power) means more 2nd order harmonics/less 3th order harmonics?
A push pull class AB amplifier (pretty much every amp that advertises putting out more than 5 watts,) with a properly balanced phase inverter will cancel out all second harmonic distortion. When it clips, it will likely still have some second harmonics from not being perfectly matched, but the dominant force will be the third harmonic. Class A single ended designs (think fender champ) are dominated by second harmonic distortion instead.
Very well done. Thank you for sharing your wisdom with us. I have a 2 sets of unknown Baldwin Transformers out of a 4 X 6L6 Hammond Organ amp chassis. I do not know how to test them. Any advice? I just subscribed to your channel!
Thanks very much, Finom 1. i could give you a more comprehensive answer if you fire me an email via the Auburn Amplifiers or Queen Bitch Amplification websites, but after checking your transformers for obvious damage, test them for DC continuity on each coil, then apply low-voltage AC to a primary (usually identifiable by wire color) and measure the resulting secondary voltage. From this you can determine impedances and whether there may be any shorted turns.
Thank you again and I will send you and email with pictures. It may lead you to make another video helping to explain methods to help individuals in my situational out the lead indentification and values for there unknown transformers. Both Power & Output!
@@Finom1 Fino, I'm very glad I've found your original message. I've lost access to our dialogue, so if you can please contact me through the Auburn Amps website or facebook page.
Do you think that if we change a tube amp transformer (let's says a mesa mark IV) for a 105 schumarer one ( like on the 2c+'s or old fender's) we gain this 3D effect on the final sound ? thanks !
This was excellent! So clear and concise. Do you think you could do a video on power transformers? Specifically the rationale on choosing/spec’ing a PT? There seem to be a million opinions about this on the forums (I assume part of this is the nature of how complex and interactive everything is within an amp...).
Thanks Josh, and thanks for your suggestion -- I'd love to do a video on PTs, especially as there's a lot to be said that could make builders' lives a lot easier. You can't always rely on what you see on forums, no matter how passionately it's expressed.
I have Fender Hot rod Deluxe burned power transformer . Is it better to change from original Fender transformer to USA made one like Classic tone or Mercury . Would you suggest one !
Is there any difference If I use a wire instead of another on the primary side (I mean, B+ or OT tube). My device doesnt have any information about It. Thanks!
please help. my peavey delta blues 2x10 amp is acting up. it goes from the normal sound (about 2) on the volume and then it gets quiet but still works. I have placed a patch chord from the effects loop send/return that helps a bit. Also, the second channel has no volume when the switch is engaged
I have a tube amp that uses 2-6v6's the speaker in the amp is a 24 ohm speaker. So I want to change the output transformer so I can use a regular 8 ohm speaker, can i select any output transformer that uses 6v6's in a push pull type amp to work?
I had a Fender Bassman 100 he uses 6L6 GC Power tubea with Push pull he runs at 4ohms. The amp it can used with only 2 tubes but I read that with 2 tubes the amps now runs at 8ohms . WHY THIS HAPPEND , could you explain me that ?
@Kevin Counihan So... If I have a transformer that puts a 1.5k load on 4 tubes which reflects to 4 ohms, and I take out 2 of the tubes, the load on the tubes will be the same but the reflected impedance will be 8 ohms?
Ok I’m pretty new to this technical stuff. My Bassman runs at 2 ohms, so if I understand correctly that’s going to decrease the 3rd order harmonics and increase the 2nd order harmonics? Do I have that right?
I have a 4 ohms amplifier solid state can I put a 16 ohms speaker?? I hear both, yes and no. I know we should not ever go below the amps ohms to a speaker, (8 ohms amp with 4 ohms speaker) this will heat up amplifier. But 16 ohms speaker to 4 ohms amp?
Hi Dave. Sorry for the late reply. Yes: you can connect a 16 ohm speaker load to a solid state amp rated for a 4 ohm load. Nothing will be damaged and the sound quality won't suffer noticeably. The only problems would be that you'd be able to access only 25% of the amp's available power, and the damping factor would be reduced by a factor of 4 (not such a big deal in most practical situations).
I ran my amp at 16 ohms into an 8 ohm cabinet for 3 years pretty loud. I figured out that I was doing it wrong. So I'm thinking about upgrading to a mercury just to be safe .It's expensive alright.
I still have to send you an email about the transformers I have and need help with. I started at your, www.queenbitchamplification.com/ , site and your - Extended amp demo - QB Little Wonder 16 watt 1x10 tube combo. That amp has caused the delay.
Thanks very much. I'm very proud of that magical little amp. Every person who has played through one - including Pat Metheny - has bought one on the spot.
![ROSÉ(로제) - APT. (Band VER.) (With. 이영지) [더 시즌즈-이영지의 레인보우] | KBS 241129 방송](http://i.ytimg.com/vi/IW8qaemx74g/mqdefault.jpg)
Finally. Someone who knows what he’s talking about. Thanks
Thank you very much for the high praise.
Best practical explanation I’ve ever heard. Thanks for making this available. I actually learned a lot today.
Great tutorial / explanation, clearly by someone that knows what they're talking about.
Nice. Succinct. Loved the push-pull cancels 2nd harmonic distortion comment.
Case in point . My next amplifier build , the power amp will be two 6v6 wired in SRPP , thus no dc bias , thus no dc core saturation in the primary coil...
Bleedin' wonderfull. What a breath of fresh air.
Very late to this party, but I have to say: great exposition! I came to this video with some trepidation but I needn't have worried. Nicely done.
I am building a replica of an old Vox amp. Its original OT had an 8K input impedance with 8 & 15 Om secondary taps. The amp was originally rated as a 10W amp, but anecdotally owners of originals and its tube compliment mean it probably pushes more like 18W when driven hard. It had 1 x 12AX7 as pre-amp and tremolo, 1 x 12AU7 for second gain stage, (cathode coupled), 1 x 12AU7 for reverb drive and recovery, 1 x 12AU7 for phase inverter, 2 x EL84 output tubes cathode biased in push/pull and 1 x EZ81 rectifier. The PT was 300-0-300V giving a DC output design V of 390V before the first dropping resistor/filter stage. The B+ was around 300V. There are no specs I can find for the original English made Drake OT which had serial nos 352-98 or 352-93. A similar OT available on the market today with similar impedance are only rated for 10 or 15W. Likely the original was only rated at 10W as owners report them running hot and they produce very compressed and nice distortion when driven with good hi end freq output. In guitar amps having an undersized core and exceeding the power rating was a very common reality. Pushing the transformer over its limits can give a nice saturated tonal quality to the sound that so many people prefer. The original OT was wound on an EI-075 lamination (35 UK style) with a 1" stack height. It looks as though it had interleaved Prim-Sec but I don't know how many. Probably on 2-2 or 2-3 given the bobbin size and stack height. My assumption therefore is that the OT might have been rated at 10W. Is it possible to get 15W rating on such a small footprint? Merc Mag make what they call an OT for this vintage amp and claim a 15W rating but this is arbitrary depending how it was measured, at what freq and into what type of load etc, so it is hard to tell. Despite running hot they seem to last despite being small for what the amp puts out when driven hard. Hammond do a 1760E for a Fender which looks like its on the same lamination. Its 8.5K prim though ion 8 and 16 Ohm Sec which should be OK with my project as A-A Imp is 8K for two EL84's in PP config. So 8.5L is very close. Is it likely something made circa 64 would have had interleaved windings between Pri and Sec. This would have added cost and inter winding capacitance would increase, but this a trade off between the reduction in eddy currents. Have I got that right. I could go up one size lamination to an EI-87 (147 UK) which is marginally bigger but allows for more intricate winding topology. However I don't want to end up with something that changes the tonal characteristics of the original. The MM OT supposedly made to suit the amp is really expensive at $212 US. Whilst it appears MM are generally more expensive than competitors it may be that some of this cost is related to the time it takes to do the interleaved windings and how many there are. The more I study the theory the harder it seams to hone in on a spec to have a OT wound to suit my project.
The output transformer on my Laney VC 30 combo creates the best harmonics i have ever heard at volume 7or 8 or higher but is renown for blowing the OT at volume 10 after some time !
The power tubes breakup with awesome aggressive slapping style but retains the articulate chord tones as you pick less forcefully !
It is great for rythem and blues !
I have other tube amps but the power tubes do not breakup like the Laney VC 30 !
The OT transformer must be the key to this tone when pushed at high volumes !
The strident highs on the amp get clipped down to a perfect timber when pushed to breakup the power tubes !
The amp has no flubby low notes but strident tight lows with authority !
I think now the OT transformer is nearly a perfect match for the 70/80 Celestion speaker and the 4- el84 power tubes !
I have not found complete information about choosing the correct transformer. The output in watts also is a factor in Plate load.There needs to be a good calculator with Tube model ,watts max, and Plate voltage. All those factors need to be considered before you divide the tube load by your impedance ratio. Plate load goes down with smaller maximum power output in watt. but goes up with higher voltages applied to Plate. Google the G.E. 6l6 gc and the Tung sol 6l6 gc data sheets. I believe screen voltage also affects plate load as well. Please let me know if there is a more complete way to calculate Plate load for output transformer primary load.
"The sound has NOTHING to do with paper insulation" THANKYOU!!! Sense at last.
Fantastic information. Thanks very much. Please keep em coming. John.
Rob, I love the discussion showing design choice of power, distortion, player style and 3rd harmonic. I've spent a considerable amount of time understanding OPT physical and circuit design (even built a cnc coil winder). I'll have to keep this tradeoff you've presented here in mind during my OPT research. Thanks. Craig
Thanks very much, Craig. Best of luck in your mindful research.
So well explained. Hope you get time to make more of these technical videos.
Thanks very much, Sam. I hope so too!
Thanks for your efforts sir
You're very welcome.
Excellent presentation!
great explanation . Thank you !
Great explanation. Thanks for your time.
Excellent
Great video, you touched on the major topics of OT' operation in a way that is easy to understand...thanks for posting this!
You're welcome Thanks very much for the nice comment.
One of the best videos I have seen on the subject... Thanks for posting.
Thanks very much. i hope to get some more videos up soon.
Very interesting, thanks for that.
Best simplest explinations so far i bump up on youtube... Thanks !
Maybe you could talk about chokes . what are their purpose in guitar amps ?
Excellent explanation. Thanks.
Great video, thank you! I have an output transformer question you might be able to help answer. Last summer I built a Mojotone black panel Princeton reverb from the kit they sell. I made a grievous error when soldering the output tubes by mis wiring one of the output wires from the phase inverter to one of the unused pins on one of the power tubes. The other power tube was wired correctly. So, one power tube was getting half phase signal and the other power tube was getting no input signal at all. I imagine the output transformer did not like this at all… not knowing what I had done, I played the amp for a few days, thinking it sounded very wrong but it might just need breaking in, lol. When the amp started cutting and out I stopped playing it, took the head out and found my mistake. So, now the amp works, sounds pretty good actually, but, and here is the issue, when I play a chord or note and let it ring out, as the note fades, there is this grungy distortion that slowly goes up in volume. It’s really bad on big jazz chords like a major 9 chord. Once again, distortion goes up as the note volume fades… after watching your video I’m am wondering if I damaged the output transformer but didn’t totally fry it… any thoughts on this?
Thanks!
Thanks very much for your comment, Omar. Chances are you have not damaged your output transformer if I understand your wiring error correctly, but a DC resistance test of both halves of the primary compared against the published spec would confirm this. You may have another wiring error to chase down, though. Tube amps are quite forgiving; component-damaging incidents are rarely subtle :)
@@robertjamesrobson2907 thanks for your input, I really appreciate it. I’ll look elsewhere to solve this issue, but for now I’m stumped, lol. It’s like the softer I play the more distorted it is… weird
I am an amateur electronic enthusiast and have a million questions, so please indulge me...
4:35 The power supply of a tube amp is a voltage supply, right? If W = V * I and I = V / R (or in this case, Z) and voltage is constant across changes in load and current, increasing the load at the same voltage would only decrease current and therefore power... so why does the power vs impedance graph have a hump instead of being a downward slope?
Most tube spec sheets I find generally show maximum plate power and maximum cathode current... how can I find maximum plate current?
Also, even if even order distortion is cancelled out in a push-pull design, one would want the load on the tubes to as low as possible (which is why I would want to know the max plate current) as to minimize odd-order distortion harmonics, right?
Finally, you covered how load impedance affects how the tubes distort... what about transformer distortion itself? I have heard that that sound is desirable in guitar amps, so would one would want a transformer as small as possible as to saturate as much as possible without blowing up? If the sound is undesirable, why aren't we using high powered toroidal transformers? Thanks!!!
Holy crap Batman; that was great!
This is gold. Thank you
Well done discription.
When reversing the output transformer plates wires the power tubes will cause oscillating & squealing, any reasons why? Also the output transformer limits the headroom the max peak AC waveform because SRV tech would swap his output transformers with dual showman output transformers or use the 50s tweed twin output transformers because it had higher headroom Cesar Diaz claimed the tweed output transformers were different for some reason
Excellent man🤘
Excellent!
So what makes an old lay down Drake sound so good? When classictones makes a vintage style OT what about it is impacting the sound (if it is)?
I would like to know what causes the el84 power tubes to breakup so harmonically on some amps but not others ?
Excellent!!
Really informative video. Superb interweaving of engineering, experience and application. Presented with style. Any guidance on wattage ratings when matching output tubes, output transformer and speaker? Especially with 'unidentified' output transformers?
Thanks very much for your kind comments, Clive. To answer your question about wattage ratings as succinctly as I can, when faced with an unknown output transformer, you can rely on the fact that manufacturers rarely stray far from norms. This means you can be fairly certain that an unknown transformer will have a similar wattage rating to others with similar core dimensions (and, by extension, weight). Online transformer catalogs provide useful access to ballpark power handling info. Just keep in mind that you can't compare single-ended with push-pull transformers this way: their constructions are different Also, some designers like their output transformers to be undersized so their cores saturate more easily (which coincidentally saves money and weight) , but for DIY projects or any application where reliability is important, there's no convincing argument for going too small IMHO. The same goes for total speaker power ratings, which must meet or exceed the amp's output if they're to last. I say 'total' because individual driver power ratings can be added of course. Incidentally, this is the sole reason larger classic amps had multiple speakers - to handle the power. It certainly wasn't done for dispersion, cost or weight reasons. i hope this answers your question!
@@q.b.amplification8056 that's really helpful info...thanks. Funny how many cost saving efforts of the past morph into the stuff of engineering legend.
@@clivebarrell6448 You've hit the nail on the head, Clive. The rarely-met challenge is to separate the beneficial flukes and genuinely effective engineering choices of old from the irrelevant and obsolete elements that continue to get cloned into guitar amp designs, feeding a cycle of myth and misunderstanding.
Great one. Thank you sir. I do love orange 5 section transformers. You have any particular faves? Happen to know the main differences (if any are main) between drake and dagnall?
Wow, thank you, Rob, great analogies too. I got here while looking for a way to play the audio from my PC on a guitar amplifier. I'm fairly sure it is an issue of impedance matching. I'm trying to play my PC's audio out (stereo headset output jack) through my guitar amp (mono input jack). I know -- I think I know -- that my PC can power 8 ohm speakers. I've heard that the input to guitar amps is Hi-Z (high impedance). So what kind of transformer do I need in order to play my PC's sound through my guitar amp? And where would I get that transformer?
Hi Ron - thanks very much for your comments. Audio transformers are generally used only where there is a need to deliver maximum signal power from the source to the load, whether this be in a tube output stage or in certain types of microphone inputs. This isn't the case with what you're wanting to do, as the low impedance output from your PC will have no difficulty driving the high-impedance input of your guitar amp. A direct connection should work fine. Your only concerns are signal voltage level and frequency response. You'll want to adjust the output level of your PC and the input gain of your amp to obtain the best balance between headroom and noise. I'd suggest starting with the amp's input gain at a low setting, then turning up the PC's output level gradually. As for frequency response, guitar amps are far from flat, so recorded music never sounds very good through them. You may need to start with the mid control up full (if there is one), and the bass and treble controls turned down, then adjust for best compromise. Short answer / good news: you don't need a transformer: just a stereo 3.5mm to mono 1/4" cable, some fiddling, and the willingness to accept less-than-stellar sound.
@@q.b.amplification8056 It works! Thanks, Rob. I had an old Acer laptop running XP (neither are really relevant). It has a separate jack for microphone and another for audio out. Plugging in an adapter somewhat like you described, a 3.5 mm mono plug with a 1/4 inch mono output, and a guitar cable between that and the guitar amp's input did the trick. As you recommended, I turned the LOW and HIGH knobs to 1 (of 10), and left the MID knob at 5 (of 10), and started with the amp volume LEVEL at 1, all this on the CLEAN channel. I found the best mix when the laptop's output was at 50%. A Crate DFX-30 was loud at a LEVEL setting of 3; a Crate DFX-65, at 1. The sound is stereo. I don't know how this will work with other computers (jack for headset with mic) and with different amps, but at least nothing bricks. Thanks again.
@@rongarza9488 You're most welcome, Ron - I'm glad it worked out. Even as a manufacturer, it makes me happy when people don't spend money needlessly.
Incredible video!
Man, this video is really enlightening. My tech thinks it’s a good idea to change the output transformer on a reissue jtm 45. Any thoughts? Thanks again. Cheers!🍷🤘
Thank you very much for this excellent tutorial. Loved it. Question: What makes a given transformer "hi-def" or "hi-fi"? As you know, these phrases are well used by people as the transformers to buy. How are these transformers different?
Great job! maybe through in leakage inductance and it's effect on frequency response,
Thanks very much, Christopher. The terms you mentioned don't have specific technical definitions - they're really just used to sell products. The engineers at McIntosh were designing beautiful transformers half a century ago - the state-of-the-art has moved forward only a relatively tiny amount since then. What constitutes hi-def and hi-fi is very subjective, although attempts have been made over the years to define hi-fi as a certain frequency range, flatness, and maximum distortion level. If you have the luxury of experimentation, the fidelity one can extract from surplus and/or modest components can be remarkable.
I have a question out of curiosity;
Does the output transformer if it's going bad will it affect the amps overdrive?. In other words will the sustain begin to diminish?
Is it worth changing over power wires black / white on fender blues junior to get 240v.
If I got a 110 amp could I just add 240 v transformer or ix that dangerous?
Great video. One question from someone for whom this is new: does this mean that a relatively colder biased amp (thus lower power) means more 2nd order harmonics/less 3th order harmonics?
Sorry for the late reply, Johan. Short answer: no, or at least not necessarily.
A push pull class AB amplifier (pretty much every amp that advertises putting out more than 5 watts,) with a properly balanced phase inverter will cancel out all second harmonic distortion. When it clips, it will likely still have some second harmonics from not being perfectly matched, but the dominant force will be the third harmonic. Class A single ended designs (think fender champ) are dominated by second harmonic distortion instead.
Very well done. Thank you for sharing your wisdom with us. I have a 2 sets of unknown Baldwin Transformers out of a 4 X 6L6 Hammond Organ amp chassis. I do not know how to test them. Any advice?
I just subscribed to your channel!
Thanks very much, Finom 1. i could give you a more comprehensive answer if you fire me an email via the Auburn Amplifiers or Queen Bitch Amplification websites, but after checking your transformers for obvious damage, test them for DC continuity on each coil, then apply low-voltage AC to a primary (usually identifiable by wire color) and measure the resulting secondary voltage. From this you can determine impedances and whether there may be any shorted turns.
Thank you again and I will send you and email with pictures. It may lead you to make another video helping to explain methods to help individuals in my situational out the lead indentification and values for there unknown transformers. Both Power & Output!
@@Finom1 Fino, I'm very glad I've found your original message. I've lost access to our dialogue, so if you can please contact me through the Auburn Amps website or facebook page.
Thank you!
Do you think that if we change a tube amp transformer (let's says a mesa mark IV) for a 105 schumarer one ( like on the 2c+'s or old fender's) we gain this 3D effect on the final sound ? thanks !
Do you know what common wire gages are used for primary and secondary on it transformers
do solide state amps use them in the same way as well?
This was excellent! So clear and concise.
Do you think you could do a video on power transformers? Specifically the rationale on choosing/spec’ing a PT? There seem to be a million opinions about this on the forums (I assume part of this is the nature of how complex and interactive everything is within an amp...).
Thanks Josh, and thanks for your suggestion -- I'd love to do a video on PTs, especially as there's a lot to be said that could make builders' lives a lot easier. You can't always rely on what you see on forums, no matter how passionately it's expressed.
I have Fender Hot rod Deluxe burned power transformer . Is it better to change from original Fender transformer to USA made one like Classic tone or Mercury . Would you suggest one !
Is there any difference If I use a wire instead of another on the primary side (I mean, B+ or OT tube). My device doesnt have any information about It. Thanks!
Nice tutorial.
please help. my peavey delta blues 2x10 amp is acting up. it goes from the normal sound (about 2) on the volume and then it gets quiet but still works.
I have placed a patch chord from the effects loop send/return that helps a bit. Also, the second channel has no volume when the switch is engaged
THANK. YOU. VERY. MUCH.
I have a tube amp that uses 2-6v6's the speaker in the amp is a 24 ohm speaker. So I want to change the output transformer so I can use a regular 8 ohm speaker, can i select any output transformer that uses 6v6's in a push pull type amp to work?
Great job
I had a Fender Bassman 100 he uses 6L6 GC Power tubea with Push pull he runs at 4ohms. The amp it can used with only 2 tubes but I read that with 2 tubes the amps now runs at 8ohms . WHY THIS HAPPEND , could you explain me that ?
@Kevin Counihan Thanks dude
@Kevin Counihan So... If I have a transformer that puts a 1.5k load on 4 tubes which reflects to 4 ohms, and I take out 2 of the tubes, the load on the tubes will be the same but the reflected impedance will be 8 ohms?
thanks
Ok I’m pretty new to this technical stuff. My Bassman runs at 2 ohms, so if I understand correctly that’s going to decrease the 3rd order harmonics and increase the 2nd order harmonics? Do I have that right?
I have a 4 ohms amplifier solid state can I put a 16 ohms speaker?? I hear both, yes and no. I know we should not ever go below the amps ohms to a speaker, (8 ohms amp with 4 ohms speaker) this will heat up amplifier. But 16 ohms speaker to 4 ohms amp?
It works perfectly fine. I've done the same thing for a year with a tube amp
Hi Dave. Sorry for the late reply. Yes: you can connect a 16 ohm speaker load to a solid state amp rated for a 4 ohm load. Nothing will be damaged and the sound quality won't suffer noticeably. The only problems would be that you'd be able to access only 25% of the amp's available power, and the damping factor would be reduced by a factor of 4 (not such a big deal in most practical situations).
@@q.b.amplification8056 Thank you. I really appreciate it.
@@rasmuslkke8233 Thanks for your advice.
How do different core compositions affect the sound of an output transformer?
I ran my amp at 16 ohms into an 8 ohm cabinet for 3 years pretty loud. I figured out that I was doing it wrong. So I'm thinking about upgrading to a mercury just to be safe .It's expensive alright.
What's a "Woburn Amplifier"? :-|
I still have to send you an email about the transformers I have and need help with. I started at your, www.queenbitchamplification.com/ , site and your - Extended amp demo - QB Little Wonder 16 watt 1x10 tube combo. That amp has caused the delay.
Thanks very much. I'm very proud of that magical little amp. Every person who has played through one - including Pat Metheny - has bought one on the spot.
Just sent you and email.
Solid state vs tube shouldnt be an argument. Quality components and good human engineering is key.