Also, Bruce Rozenblit of Transcendent Sound. The output transformer quality is often the limiter to performance and certainly is the big cost of a tube amp. OTL done right is pretty darned good.
Transformers also are used to get push-pulll operation without complementary devices. It's not the only way but since the impedance conversion is fairly necessary, may as well get the plusses of center tapping the primary, multiple taps on the output, and no DC on the output no matter how it is biased. Along with some disadvantages. The power transformer is often bigger anyway, although the output tx more difficult.
Another reason for output transformers, a push-pull output is desirable as it reduces odd-order harmonics which people find unpleasant, but, tubes only come in one polarity, unlike transistors, so the only way to get push-pull in a tube amp is with the aid of a transformer, even assuming you had a very high impedance speaker.
I have an old danish amp with quasi complimentary germanium outputs and output transformers. There are also loads of Nelson Pass transistor amps with output transformers.
Always seems a topic of interest. And I enjoy hearing you go through the effort regularly. Gives me a chance to think about it some more. And you triggered a new approach to this for me just now. Perhaps as often happens, the discussion is not framed properly? Amps take a given voltage input, usually around 1-2VAC peak? and increase the voltage to some greater level depending on the output technology and design. Then that increased voltage is matched as best as possible and couple to the load. We tend to think of these stages based on technology type, solid state vs tube, differently. Solid State being simply input to gain stage to output devices stage and to the load. We tend to compare tubes using the same input to gain stage to output tubes to transformer to load. As if the transformer was an additional stage. But all it is doing is matching the PS to the load just as the output devices in an SS amp do. The actual "output" stage in a SS amp is the driver stage that adds voltage gain to send to the output devices. In fact an output stage can go out and the drive stage can feed the load. It just has no current behind it! So it is more accurate to reference the transformer as a passive matching stage in comparison to an active device matching stage in an SS amp. Rather than as some additional STAGE/ component needed to match. Interestingly this matches your earlier videos on your ultimate amp design. That you had to be convinced that the ultimate design is tube gain/ drivers and SS output. You initially rejected that approach. But if you think about it from this approach, it is a natural. You get the sound of the tube amp using an active matching system rather than passive transformers.
Man there has to be a less windy way to say whatever you said. Nothing personal but I'm not an engineer or a so called audiophile. So call the guy up his business phone is listed or easily found on Google. And spare me the rebuttal. Hmmmf.
@@larryh.4629 There are less windy ways for the less educated as you state yourself to be. There are also massive books written for those with the ability to comprehend it.
Good stuff. I think that the output transformer on a tube amp, because its basically two inductors, side by side, affects harmonic content. I suspect that this is part of the "warm" sound that people talk about with tube amps. Interestingly, I suspect that Peavey's reason for including a transformer, driving the two output transistors, is to get some of this "warmth" in the sound of one of their solid state amps. Specifically, I'm talking about a Peavey Pacer guitar amp. Pehaps this isn't the only reason for the transformer use? Maybe the transformer is used to create the positive and negative halfs of a sine waver? Someone out there, who knows more about this subject, please comment.
Yeah. Also, an interesting difference between tube and transistor amps is that for a transistor amp, the speaker impedance should not be lower than specified or you may damage the amp, but for a tube amp the speaker impedance should not be higher than specified and you should never run a tube amp without any load. Connecting 4ohm speakers to an 16ohm tap reduces the power, but is otherwise OK. Connecting 16ohm speakers to a 4ohm tap reduces the power and may damage the amp if you turn the volume up too much.
Great video as always! I got a question that I think gets more and more relevant now when the class D amplifiers get better and better and are close to acting as a amplifier without any distortion or added color to the signal. Might be good for the sound but if everything is this clean you can only listen to audiophile records (rather boring for music lovers like me). I have a theory that audio transformers like Lundahl LL1527 are better to color the sound then a tube pre-amplifier and that this combination is almost forgotten. What do you thing about class D amplifiers with audio transformer inputs?
Can you do a video on interstate transformer, im newer to building hifi stuff, i build a ton of guitar amps, i came i into a huge collection of hifi stuff, and its so differnt to me. Guitar amp are simple preamps and power amps with coupling caps inbetween, but hifi tubes with lower heater voltages and interstste transformers are a learning process.
Does music keep the body in sync..? What is music moving through the air.? Energy on a molecular scale.? Waves of Atoms,molecules and electrons that are riding the sound waves into the ears and into the brain cells. Where do they go from there..???
Yes there are - they are winded in such special (and difficult) way that the length of wires in two parts of B class transormer is near equal, say up to 5% . It is not big difference to standard with differences some 25% because we care for impedances and they are secured equal but secures identical anode volltages on both tubes . If we consider matching tubes as so important it is justified to consider matching their windings,.
Sonically, the output transformer may be the single most critical component in a tube amp. That's why really good ones are so expensive. They may also be large and heavy, but the truth is, cheaply made OTs may contain a lot of iron, too, and thus be humongous, so size alone is not an indication of quality (building OTs is an art: a combination of power capacity, bandwidth and isolation). Apart from the tubes themselves, which are in fact the amplifier (the actual amplifying device), the other crucial components include power supply, coupling capacitors and output transformers (with the exception of OTL, i.e. output-transformer-less). Of these, coupling capacitors and output transformers can be thought of as bottlenecks - they degrade and cannot possibly "improve" the sound, in other words, they literally can't be good enough.
Howdy. My DIY 4 x KT88 PA sounds OK. However. The low damping of tube OPT:s make my only medium quality Simex loudspeakers sound dark. They sound dark naturally but the low damping worsens the situation. Actually the reflex resonance produces an awful pealing sound. Long live Solid State. Regards.
It gets very fragile with many thin windings on the speaker coil. The result is a speaker that is incompatible with solid state amplifiers. Philips made speakers like that with an 800 Ohm impedance. They developed specifically a tube to drive them, the EL86, the low impedance brother of the well known EL84 output tube. The single ended amplifier version was used in TV sets and cheap tube radios. But they also had a 10W push pull HiFi amplifier capable of driving the 800 Ohm version of an AD9710, which is an 8" full range AlNiCo speaker. These speakers have a cult following and the 800 Ohm versions are the most expensive ones today, because it will allow you to build an OTL amplifier for it.
@@hugobloemers4425 Correct - I was meditating to get such speakers, One of them I had in B_W mono philips TV and I may say comparing to usual TVs it was much better audio. But later I found that with standard impedance and transformers all also may be done
@@Mikexception Yeh, but then you have a transformer again. I agree, old Philips TV's sound exceptionally well: Big wooden enclosure, curved picture tube to fight standing waves, single ended tube OTL amplifier (that sounds audiophile by it self) 5" or 6" full range AlNiCo driver.
@@hugobloemers4425 Regarding damping factor I made some simplified calculations for solid state output impedance and measured my vintage moderate power tube output transformer impedance - 150 mH Resistance at 8 Ohm terminal is 1,0 Ohm . All together at 20 Hz without feedback creates 3 Ohm damping load Typical output capacitance 2000 uF for solid amplifier plus 0,3 Ohm output resistance crerates for 20 Hz 3,8 Ohm capacity impedance. It means they are similar . Difference is that for solid amplifier with falling down to "0"Hz frequency damping load vanishes . In transformer output damping load grows to maximum reaching finaly at "0" Hz 1 Ohm. . Output circuit in solid amplifier creates serial resonance loop which I calculate is 5- 25 Hz - it is speaker coil with capacity While in transformer ouput it is not happening due to not used capacitance. Conclusions I leave open .
the output transformer and tube output stage is nolonger needed.. pauls statements about current and voltage is wrong also. he smushed bjt and fet devices in one lump..and they are totally different.. the guy that stated that the output transformer ruins damping factor is correct.. WE HAVE KNOW HOW TO implement tubes in the drive stage and use N channel fets in the output stage and combine the best stages to build reliable great sounding amps without the need for large amount of negative feedback and still equal the zero feedback designs .but more reliable..with no thermal runaway..
The best way to drive a speaker is with zero Ohms output impedance and a voltage that exactly tracks the input signal. This is the ideal condition and using tubes and output transformers in a power amplifier is polluting the signal path messing up the damping factor and frequency response (impedance dependent). Any serious audiophile purist want the cleanest signal possible to the speakers and definitely a tube amplifier is not the way to go today. Yeah, if you have a power amplifier too weak on power, then tubes clip in a more musical way (even harmonics distortion), but why the heck do you want a system where clipping even becomes an issue? Just get a power amplifier with adequate power to play loud and clean with no such clipping and you get the best performance. I rather have no distortion than some tube distortion. Anyone who considers himself as "audio purist" and likes tube distortion is in conflict with himself. It's OK to like tube distortion (if it makes you happy) but please don't think you are purist.
How about people who are NOT purist, but just want sound THEY like? It is all fake any way, no matter what. Now you just have to decide on what kind of fake you prefer.
@@hugobloemers4425 Of course that's what this hobby should about. Whatever makes us happy in our audio hobby, we should do. I didn't say it's not great to be a tube fan, if that is what makes you happy. If I had a choice between a 1 Watt tube amp and 1 Watt transistor amp, I would probably prefer the tube amp because I would end up hitting the max power too often. But rather I would just buy a >100 Watt amp and not bother with clipping. Another way to get the tube distortion is with using DSP. Actually, a DSP is much better in making tube distortion because it can be precisely calibrated and not drift over time like tubes always do. Someone should design an audiophile DSP tube distortion device that genuinely sounds like real tubes but even more optimized. These things tend to exist only in professional studios e.g. as DAW plugins.
Poetic and emotional point of view tells about "serious audiophiles" and "cleanest signal possible" but it is the world of fairytales - comparable to "serious dragons" and "pure princesses". If you believe it engineering it is for you obligatory to describe who do you mean serious audiophile and show us the cleanest signal possible.
I have been attacked for saying how I am using this guy’s videos to increase my knowledge of Audio equipment.
Perfect explanation ! Indeed, David Berning and his OTL amplifiers are legendary !
Also, Bruce Rozenblit of Transcendent Sound.
The output transformer quality is often the limiter to performance and certainly is the big cost of a tube amp. OTL done right is pretty darned good.
Paul is fast becoming my knowledge source.
Oh my Goodness
all have the right to choose to be or are Myopically inclined
Transformers also are used to get push-pulll operation without complementary devices. It's not the only way but since the impedance conversion is fairly necessary, may as well get the plusses of center tapping the primary, multiple taps on the output, and no DC on the output no matter how it is biased. Along with some disadvantages. The power transformer is often bigger anyway, although the output tx more difficult.
Paul knows everything
Are You joking?
Another reason for output transformers, a push-pull output is desirable as it reduces odd-order harmonics which people find unpleasant, but, tubes only come in one polarity, unlike transistors, so the only way to get push-pull in a tube amp is with the aid of a transformer, even assuming you had a very high impedance speaker.
Thank you for explaining
I have an old danish amp with quasi complimentary germanium outputs and output transformers. There are also loads of Nelson Pass transistor amps with output transformers.
Always seems a topic of interest. And I enjoy hearing you go through the effort regularly. Gives me a chance to think about it some more. And you triggered a new approach to this for me just now. Perhaps as often happens, the discussion is not framed properly?
Amps take a given voltage input, usually around 1-2VAC peak? and increase the voltage to some greater level depending on the output technology and design. Then that increased voltage is matched as best as possible and couple to the load. We tend to think of these stages based on technology type, solid state vs tube, differently.
Solid State being simply input to gain stage to output devices stage and to the load.
We tend to compare tubes using the same input to gain stage to output tubes to transformer to load. As if the transformer was an additional stage.
But all it is doing is matching the PS to the load just as the output devices in an SS amp do. The actual "output" stage in a SS amp is the driver stage that adds voltage gain to send to the output devices. In fact an output stage can go out and the drive stage can feed the load. It just has no current behind it!
So it is more accurate to reference the transformer as a passive matching stage in comparison to an active device matching stage in an SS amp. Rather than as some additional STAGE/ component needed to match.
Interestingly this matches your earlier videos on your ultimate amp design. That you had to be convinced that the ultimate design is tube gain/ drivers and SS output. You initially rejected that approach. But if you think about it from this approach, it is a natural. You get the sound of the tube amp using an active matching system rather than passive transformers.
Man there has to be a less windy way to say whatever you said. Nothing personal but I'm not an engineer or a so called audiophile. So call the guy up his business phone is listed or easily found on Google. And spare me the rebuttal. Hmmmf.
@@larryh.4629 There are less windy ways for the less educated as you state yourself to be. There are also massive books written for those with the ability to comprehend it.
Good stuff. I think that the output transformer on a tube amp, because its basically two inductors, side by side, affects harmonic content. I suspect that this is part of the "warm" sound that people talk about with tube amps. Interestingly, I suspect that Peavey's reason for including a transformer, driving the two output transistors, is to get some of this "warmth" in the sound of one of their solid state amps. Specifically, I'm talking about a Peavey Pacer guitar amp. Pehaps this isn't the only reason for the transformer use? Maybe the transformer is used to create the positive and negative halfs of a sine waver? Someone out there, who knows more about this subject, please comment.
@Douglas Blake Cool, thanks for the information !
Oh. That may explain why many tube amps have impedance taps at the speaker connections.
Yeah. Also, an interesting difference between tube and transistor amps is that for a transistor amp, the speaker impedance should not be lower than specified or you may damage the amp, but for a tube amp the speaker impedance should not be higher than specified and you should never run a tube amp without any load.
Connecting 4ohm speakers to an 16ohm tap reduces the power, but is otherwise OK. Connecting 16ohm speakers to a 4ohm tap reduces the power and may damage the amp if you turn the volume up too much.
thank you idol..
Great video as always!
I got a question that I think gets more and more relevant now when the class D amplifiers get better and better and are close to acting as a amplifier without any distortion or added color to the signal. Might be good for the sound but if everything is this clean you can only listen to audiophile records (rather boring for music lovers like me). I have a theory that audio transformers like Lundahl LL1527 are better to color the sound then a tube pre-amplifier and that this combination is almost forgotten. What do you thing about class D amplifiers with audio transformer inputs?
Can you do a video on interstate transformer, im newer to building hifi stuff, i build a ton of guitar amps, i came i into a huge collection of hifi stuff, and its so differnt to me. Guitar amp are simple preamps and power amps with coupling caps inbetween, but hifi tubes with lower heater voltages and interstste transformers are a learning process.
Does music keep the body in sync..?
What is music moving through the air.?
Energy on a molecular scale.?
Waves of Atoms,molecules and electrons that are riding the sound waves into the ears and into the brain cells. Where do they go from there..???
That should not be controversial :)
Do different output transformers give different sound quality?
Surely that must be a rhetorical question.
Yes there are - they are winded in such special (and difficult) way that the length of wires in two parts of B class transormer is near equal, say up to 5% . It is not big difference to standard with differences some 25% because we care for impedances and they are secured equal but secures identical anode volltages on both tubes . If we consider matching tubes as so important it is justified to consider matching their windings,.
Sonically, the output transformer may be the single most critical component in a tube amp. That's why really good ones are so expensive. They may also be large and heavy, but the truth is, cheaply made OTs may contain a lot of iron, too, and thus be humongous, so size alone is not an indication of quality (building OTs is an art: a combination of power capacity, bandwidth and isolation). Apart from the tubes themselves, which are in fact the amplifier (the actual amplifying device), the other crucial components include power supply, coupling capacitors and output transformers (with the exception of OTL, i.e. output-transformer-less). Of these, coupling capacitors and output transformers can be thought of as bottlenecks - they degrade and cannot possibly "improve" the sound, in other words, they literally can't be good enough.
@@EliasTheHunter
I’d say he definitely knows what a rhetorical question is..
@@EliasTheHunter Appears to me he knows full well what a rhetorical question is - do you?
Howdy.
My DIY 4 x KT88 PA sounds OK. However. The low damping of tube OPT:s make my only medium quality Simex loudspeakers sound dark. They sound dark naturally but the low damping worsens the situation. Actually the reflex resonance produces an awful pealing sound. Long live Solid State.
Regards.
Why dont some speakers have higher impedance like some headphones
It gets very fragile with many thin windings on the speaker coil. The result is a speaker that is incompatible with solid state amplifiers. Philips made speakers like that with an 800 Ohm impedance. They developed specifically a tube to drive them, the EL86, the low impedance brother of the well known EL84 output tube. The single ended amplifier version was used in TV sets and cheap tube radios. But they also had a 10W push pull HiFi amplifier capable of driving the 800 Ohm version of an AD9710, which is an 8" full range AlNiCo speaker. These speakers have a cult following and the 800 Ohm versions are the most expensive ones today, because it will allow you to build an OTL amplifier for it.
@@hugobloemers4425 Correct - I was meditating to get such speakers, One of them I had in B_W mono philips TV and I may say comparing to usual TVs it was much better audio. But later I found that with standard impedance and transformers all also may be done
@@Mikexception Yeh, but then you have a transformer again. I agree, old Philips TV's sound exceptionally well: Big wooden enclosure, curved picture tube to fight standing waves, single ended tube OTL amplifier (that sounds audiophile by it self) 5" or 6" full range AlNiCo driver.
@@hugobloemers4425 Regarding damping factor I made some simplified calculations for solid state output impedance and measured my vintage moderate power tube output transformer impedance - 150 mH Resistance at 8 Ohm terminal is 1,0 Ohm . All together at 20 Hz without feedback creates 3 Ohm damping load
Typical output capacitance 2000 uF for solid amplifier plus 0,3 Ohm output resistance crerates for 20 Hz 3,8 Ohm capacity impedance. It means they are similar
.
Difference is that for solid amplifier with falling down to "0"Hz frequency damping load vanishes . In transformer output damping load grows to maximum reaching finaly at "0" Hz 1 Ohm. . Output circuit in solid amplifier creates serial resonance loop which I calculate is 5- 25 Hz - it is speaker coil with capacity While in transformer ouput it is not happening due to not used capacitance. Conclusions I leave open .
Some people like the OTL sound but for me they are too lush and slow.
the output transformer and tube output stage is nolonger needed.. pauls statements about current and voltage is wrong also. he smushed bjt and fet devices in one lump..and they are totally different.. the guy that stated that the output transformer ruins damping factor is correct.. WE HAVE KNOW HOW TO implement tubes in the drive stage and use N channel fets in the output stage and combine the best stages to build reliable great sounding amps without the need for large amount of negative feedback and still equal the zero feedback designs .but more reliable..with no thermal runaway..
The best way to drive a speaker is with zero Ohms output impedance and a voltage that exactly tracks the input signal. This is the ideal condition and using tubes and output transformers in a power amplifier is polluting the signal path messing up the damping factor and frequency response (impedance dependent). Any serious audiophile purist want the cleanest signal possible to the speakers and definitely a tube amplifier is not the way to go today. Yeah, if you have a power amplifier too weak on power, then tubes clip in a more musical way (even harmonics distortion), but why the heck do you want a system where clipping even becomes an issue? Just get a power amplifier with adequate power to play loud and clean with no such clipping and you get the best performance. I rather have no distortion than some tube distortion. Anyone who considers himself as "audio purist" and likes tube distortion is in conflict with himself. It's OK to like tube distortion (if it makes you happy) but please don't think you are purist.
How about people who are NOT purist, but just want sound THEY like?
It is all fake any way, no matter what. Now you just have to decide on what kind of fake you prefer.
@@hugobloemers4425 Of course that's what this hobby should about. Whatever makes us happy in our audio hobby, we should do. I didn't say it's not great to be a tube fan, if that is what makes you happy. If I had a choice between a 1 Watt tube amp and 1 Watt transistor amp, I would probably prefer the tube amp because I would end up hitting the max power too often. But rather I would just buy a >100 Watt amp and not bother with clipping. Another way to get the tube distortion is with using DSP. Actually, a DSP is much better in making tube distortion because it can be precisely calibrated and not drift over time like tubes always do. Someone should design an audiophile DSP tube distortion device that genuinely sounds like real tubes but even more optimized. These things tend to exist only in professional studios e.g. as DAW plugins.
Poetic and emotional point of view tells about "serious audiophiles" and "cleanest signal possible" but it is the world of fairytales - comparable to "serious dragons" and "pure princesses". If you believe it engineering it is for you obligatory to describe who do you mean serious audiophile and show us the cleanest signal possible.
@@ThinkingBetter These plugins exist also in non professional studios because even the good ones are not really expensive any more.
*themself, not “himself”