Having just acquired some 100 dB drivers, I am now getting interested in building a tube amp. 20 watts is the probable minimum.
Having no experience and little time, it’ll probably be a kit. There are many, even clones of a 40 yo design the Dynaco.
I believe Dynaco’s are well regarded, but wonder – how much development has there been in the 40 years since then? Maybe only 5% of amps built over that period were tube, but many of the builders are very keen DIYers.
In that time in the rest of the audio world we’ve had eg
- much better understanding of horn design (Edgar, Danley)
- metal cone drivers tamed,
- chip amps for bang for buck,
- woofers and mids with 2-3 times the Xmax of a generation ago,
- powerful FR dipoles that only just break the bank (Linkwitz), etc.
(I know not all would call all of these advances).
So what are the advances in tube amp design?
Yes we need to implement them properly, but what are the great designs?
Having no experience and little time, it’ll probably be a kit. There are many, even clones of a 40 yo design the Dynaco.
I believe Dynaco’s are well regarded, but wonder – how much development has there been in the 40 years since then? Maybe only 5% of amps built over that period were tube, but many of the builders are very keen DIYers.
In that time in the rest of the audio world we’ve had eg
- much better understanding of horn design (Edgar, Danley)
- metal cone drivers tamed,
- chip amps for bang for buck,
- woofers and mids with 2-3 times the Xmax of a generation ago,
- powerful FR dipoles that only just break the bank (Linkwitz), etc.
(I know not all would call all of these advances).
So what are the advances in tube amp design?
Yes we need to implement them properly, but what are the great designs?
None. All tube topologies were covered 40 years ago (even things as complicated as color television). All topologies that work better than newer, supercomplicated circuits (which again, were developed 40+ years ago) were covered over 70 years ago.
Go with something known and good, two billion of something just means it sold well, not that it was well made. At the very worst we can draw up something for you.
I doubt you'll need much more than 10W at that efficiency level, so something SE might work for 'ya. If you do, well, loud death metal and horns are kind of mutually exclusive, so you don't...
Tim
Go with something known and good, two billion of something just means it sold well, not that it was well made. At the very worst we can draw up something for you.
I doubt you'll need much more than 10W at that efficiency level, so something SE might work for 'ya. If you do, well, loud death metal and horns are kind of mutually exclusive, so you don't...
Tim
Interesting answers.
So you two are saying that while the general body of audio knowledge grew, pretty much all of science & technology grew; tube amp knowledge *shrank?
And there are **zero new good ideas in **40 years**??
That sounds like something out of a science fiction horror movie- "the Land where Time stood Still"
What about Direct Reactance Drive (www.welbornelabs.com/)?
- Single-ended OTL pure Class A (www.transcendentsound.com/single ended.htm )?
Ie “New Tube power amp topologies 1966 – 2005” = Nil return ??
Is this the most stagnant area of applied science of the late 20th century??
How does a newbie sort the wheat from the chaff?
So you two are saying that while the general body of audio knowledge grew, pretty much all of science & technology grew; tube amp knowledge *shrank?
And there are **zero new good ideas in **40 years**??
That sounds like something out of a science fiction horror movie- "the Land where Time stood Still"
What about Direct Reactance Drive (www.welbornelabs.com/)?
- Single-ended OTL pure Class A (www.transcendentsound.com/single ended.htm )?
Ie “New Tube power amp topologies 1966 – 2005” = Nil return ??
Is this the most stagnant area of applied science of the late 20th century??
How does a newbie sort the wheat from the chaff?
There are maybe not so many new ideas but there are, as in all things, stuff that comes into fashion. In fashion right now are probably some of the following:
Interstage and input transformers
Transformer volume controls
Constant current sinks for diff pairs (CCS)
Active CCS loads for tubes
Choke loaded stages
Parafeed
SET amps
Directly Heated Triodes (DHTs)
Zero global feedback in triode output stages
While most of this is old technology there are new implementations, especially with CCS. It is worth pointing out that the Dynaco circuit contains none of the above.
Interstage and input transformers
Transformer volume controls
Constant current sinks for diff pairs (CCS)
Active CCS loads for tubes
Choke loaded stages
Parafeed
SET amps
Directly Heated Triodes (DHTs)
Zero global feedback in triode output stages
While most of this is old technology there are new implementations, especially with CCS. It is worth pointing out that the Dynaco circuit contains none of the above.
The Dyna circuitry wasn't even sota at the time. It was designed to be good enough and low parts count. The iron and chassis are just fine, but any modern design will include regulated power supplies and a high-quality driver.
There are lots of things touted as new, most of which came out of cheap kids' toys, had a fancy name slapped on them, and are now fashionable. Tubes are by their nature quite limiting (there is no "p-channel" tube, for example) so most anything worth doing has been done. The one guy who has done truly new things is Dave Berning- screen drive, switching supplies, tube-FET hybrids, digital autobias, impedance mapping- but this is not the stuff of fashion or audiophile candy.
There are lots of things touted as new, most of which came out of cheap kids' toys, had a fancy name slapped on them, and are now fashionable. Tubes are by their nature quite limiting (there is no "p-channel" tube, for example) so most anything worth doing has been done. The one guy who has done truly new things is Dave Berning- screen drive, switching supplies, tube-FET hybrids, digital autobias, impedance mapping- but this is not the stuff of fashion or audiophile candy.
SY
I suspected as much about the Dyna circuitry.
Dave Berning - is it better?? /where do I learn more/ public domain DIY?
Andy
Is there nought but fashion in the tube amp world?
Are new implementations with CCS worthwhile?
JM, you've raised some intriguing issues:
>> You forget that there was a large chunk of time where virtually everyone ran away from valves as fast as they could.
note: I have
a few, but I assure it hasn'tv affected my logib
I didn’t know there had been a Diaspora. Not Politically Correct.
If this continues, I’ll write to my local Member about this.
>> Lots of stuff was forgotten and is being rediscovered.
Forgotten? and rediscovered??
Were these the Dark Ages, and now the Renaissance?
I read of events like this, in the LotR. Or was it Harry Potter?
Either way, it looked very good on the Big Screen.
>> The examples of "new" you give aren't remotely new!
I did not know if they were new, but they sounded different, and strangely alluring to my wallet, promising the elusive “Audio Nirvana”.
I hear you can get it in a bottle in outer Tibet? Is this true??
How does a newbie sort the wheat from the chaff?
>> The obvious way... Listen!
What, use my ears?? Let’s not get physical just yet matey.
Some say, the best way, where feasible. If not, (I) seek the (more elusive than a Haitian shakri) “ ‘opinions’ “.
My girlfriend reckons I should just improve my technique, and all will become “cool”? but I could not find that in my Audio Glossary.
That’s why I’m here, blown off a local redneck audio forum where no moderator controlled events when emotions on this issue bubbled brewed and seethed like a witch’s spell.
I just found an amp design approved by Lord Kitchener, as used in the Boer War. Apparently it is pretty well “State of the Art”.
Based on your opinoions, I’m placing my purchase order now, thank you for you assistances.
Yours,
The Colonel
I suspected as much about the Dyna circuitry.
Dave Berning - is it better?? /where do I learn more/ public domain DIY?
Andy
Is there nought but fashion in the tube amp world?
Are new implementations with CCS worthwhile?
JM, you've raised some intriguing issues:
>> You forget that there was a large chunk of time where virtually everyone ran away from valves as fast as they could.
note: I have
a few, but I assure it hasn'tv affected my logib I didn’t know there had been a Diaspora. Not Politically Correct.
If this continues, I’ll write to my local Member about this.
>> Lots of stuff was forgotten and is being rediscovered.
Forgotten? and rediscovered??
Were these the Dark Ages, and now the Renaissance?
I read of events like this, in the LotR. Or was it Harry Potter?
Either way, it looked very good on the Big Screen.
>> The examples of "new" you give aren't remotely new!
I did not know if they were new, but they sounded different, and strangely alluring to my wallet, promising the elusive “Audio Nirvana”.
I hear you can get it in a bottle in outer Tibet? Is this true??
How does a newbie sort the wheat from the chaff?
>> The obvious way... Listen!
What, use my ears?? Let’s not get physical just yet matey.
Some say, the best way, where feasible. If not, (I) seek the (more elusive than a Haitian shakri) “ ‘opinions’ “.
My girlfriend reckons I should just improve my technique, and all will become “cool”? but I could not find that in my Audio Glossary.
That’s why I’m here, blown off a local redneck audio forum where no moderator controlled events when emotions on this issue bubbled brewed and seethed like a witch’s spell.
I just found an amp design approved by Lord Kitchener, as used in the Boer War. Apparently it is pretty well “State of the Art”.
Based on your opinoions, I’m placing my purchase order now, thank you for you assistances.
Yours,
The Colonel
Berning's web site is a treasure trove of truly original designs; he's posted schematics for all of his designs going back to the '70s (see the "Support" section). His US patents are well worth some study. www.davidberning.com
Is his stuff "good"? Depends on your definition of "good." It's efficient, lightweight, and stable. For many, that's no fun.
Is his stuff "good"? Depends on your definition of "good." It's efficient, lightweight, and stable. For many, that's no fun.
New, not new? I don't know, but informative for sure:
http://members.aol.com/sbench101/
http://www.tubecad.com/
Sheldon
http://members.aol.com/sbench101/
http://www.tubecad.com/
Sheldon
Andy
Is there nought but fashion in the tube amp world?
Are new implementations with CCS worthwhile?>
I'll leave the fashion question, but say that CCS are definitely A GOOD THING. To get on the trail of some of this stuff, put your money down on Morgan Jones Valve Amplifiers ed 3. You will find the CCS on page 134 for starters, plus all kinds of practical help in building your projects. Many of us started building seriously as a result of studying this book (in my case again and again and again - takes time for some of it to sink in!)
A diff pair with a CCS in the cathode is an effective input stage, but only one of many (and the others are in Morgan's book). Useful thing is it can be used for both single ended and balanced input, so it's a versatile thing to be able to construct for your projects. Andy
Is there nought but fashion in the tube amp world?
Are new implementations with CCS worthwhile?>
I'll leave the fashion question, but say that CCS are definitely A GOOD THING. To get on the trail of some of this stuff, put your money down on Morgan Jones Valve Amplifiers ed 3. You will find the CCS on page 134 for starters, plus all kinds of practical help in building your projects. Many of us started building seriously as a result of studying this book (in my case again and again and again - takes time for some of it to sink in!)
A diff pair with a CCS in the cathode is an effective input stage, but only one of many (and the others are in Morgan's book). Useful thing is it can be used for both single ended and balanced input, so it's a versatile thing to be able to construct for your projects. Andy
New tube technology:
Vacuum tube current mirrors:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=40595&highlight=
No filament vacuum tubes:
http://www.diyaudio.com/forums/showthread.php?postid=314784#post314784
http://www.diyaudio.com/forums/showthread.php?postid=577176#post577176
Inverted triode feedback:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=20686&highlight=
Hawksford style error correcting output:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35001&highlight=
Hybrid current mirror outputs:
http://www.diyaudio.com/forums/showthread.php?postid=529831#post529831
Elliptron output:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=19624&highlight=
Improved Berning impedance converter:
http://www.diyaudio.com/forums/showthread.php?postid=411345#post411345
Beyond UltraLinear:
http://www.diyaudio.com/forums/showthread.php?postid=590895#post590895
Gain multiplier feedback (this uses the tail current on an LTP to modulate gain to correct distortion rather than the usual subtractive negative feedback, advantage is low gain requirement compared to conventional NFB):
http://www.diyaudio.com/forums/showthread.php?postid=357175#post357175
haven't posted yet, but presently working on Hawksford Error correction technique applied to Vacuum Tube Current Mirrors with current gain.
Don
Vacuum tube current mirrors:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=40595&highlight=
No filament vacuum tubes:
http://www.diyaudio.com/forums/showthread.php?postid=314784#post314784
http://www.diyaudio.com/forums/showthread.php?postid=577176#post577176
Inverted triode feedback:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=20686&highlight=
Hawksford style error correcting output:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35001&highlight=
Hybrid current mirror outputs:
http://www.diyaudio.com/forums/showthread.php?postid=529831#post529831
Elliptron output:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=19624&highlight=
Improved Berning impedance converter:
http://www.diyaudio.com/forums/showthread.php?postid=411345#post411345
Beyond UltraLinear:
http://www.diyaudio.com/forums/showthread.php?postid=590895#post590895
Gain multiplier feedback (this uses the tail current on an LTP to modulate gain to correct distortion rather than the usual subtractive negative feedback, advantage is low gain requirement compared to conventional NFB):
http://www.diyaudio.com/forums/showthread.php?postid=357175#post357175
haven't posted yet, but presently working on Hawksford Error correction technique applied to Vacuum Tube Current Mirrors with current gain.
Don
I think I will add some opinion on progress since the transistor.
The transistor did give us more efficiency, but:
1. "Compared to tubes, transistors can last forever". I specifically remember hearing this statement back in the 60's and 70's. It was a lie. I am now using tubes made in the 50's that work fine. Non of my electronics from the 80's still work! But some idiots still believe this lie.
2. Transistor vs Tube sound. I recently built a variety of simple amps to see for myself, including: chip amp based on NS chips, MOSFET class A amp, SET, and Triode PP amp. Either of my tube amps clearly beat the chip amp in dynamics and other ways, and were also a little better than the mosfet amp. I did not use test equipment, just my ears. And the difference was obvious.
3. Digital vs Analog sources. After enjoying CD's for twenty years now, I had a chance to listen again to records for the first time in many years. I was impressed. Not with the old pops and crackles, but in how natural it sounded, particularly with voice (which our ears are finely trained in). Some progress!
Now there are two ways of thinking in this world.... you can listen to what other people say and just believe them, OR, you can form your beliefs based on your own investigation and using critical thinking (which admittedly, is the hard way). I have chosen to trust my ears and brain. The results of that have taught me:
1. Sound "quality" is subjective, and music comes in many forms. A Kick-*** rocker ain't gonna be happy with a 4 inch full-range, no matter what (well okay, a Bose 901 version of that maybe!). But a good ear can hear quality, and you tell what sounds right or not.
2. Based on my experience, I would say (with the exception of speakers)that decent quality modern electronics is not better than 40 years ago, it is worse. It sounds worse, it does not last as long. It is Throw-away equipment.
3. Based on the above and what I hear and see in the market place, many people (including some audiophiles) must be idiots with tin ears. I cannot believe the junk that manufacturers sell today, and the customers acceptance of it. Even in the audiophile world. Either people really are fools, are they just don't care. I hope it's the last one, but it pains me think that it's probably a combination of the two. How sad.
Completely sincerely,
Kent
The transistor did give us more efficiency, but:
1. "Compared to tubes, transistors can last forever". I specifically remember hearing this statement back in the 60's and 70's. It was a lie. I am now using tubes made in the 50's that work fine. Non of my electronics from the 80's still work! But some idiots still believe this lie.
2. Transistor vs Tube sound. I recently built a variety of simple amps to see for myself, including: chip amp based on NS chips, MOSFET class A amp, SET, and Triode PP amp. Either of my tube amps clearly beat the chip amp in dynamics and other ways, and were also a little better than the mosfet amp. I did not use test equipment, just my ears. And the difference was obvious.
3. Digital vs Analog sources. After enjoying CD's for twenty years now, I had a chance to listen again to records for the first time in many years. I was impressed. Not with the old pops and crackles, but in how natural it sounded, particularly with voice (which our ears are finely trained in). Some progress!
Now there are two ways of thinking in this world.... you can listen to what other people say and just believe them, OR, you can form your beliefs based on your own investigation and using critical thinking (which admittedly, is the hard way). I have chosen to trust my ears and brain. The results of that have taught me:
1. Sound "quality" is subjective, and music comes in many forms. A Kick-*** rocker ain't gonna be happy with a 4 inch full-range, no matter what (well okay, a Bose 901 version of that maybe!). But a good ear can hear quality, and you tell what sounds right or not.
2. Based on my experience, I would say (with the exception of speakers)that decent quality modern electronics is not better than 40 years ago, it is worse. It sounds worse, it does not last as long. It is Throw-away equipment.
3. Based on the above and what I hear and see in the market place, many people (including some audiophiles) must be idiots with tin ears. I cannot believe the junk that manufacturers sell today, and the customers acceptance of it. Even in the audiophile world. Either people really are fools, are they just don't care. I hope it's the last one, but it pains me think that it's probably a combination of the two. How sad.
Completely sincerely,
Kent
> how much development has there been in the 40 years since then?
Some small improvements. Sand-state makes many tube-things easier, and possibly "better". I would not use tubes any more if I had to use hollow-state rectifiers (others disagree).
But they knew what they were doing when the world revolved around tubes. Talking movie systems were very advanced in the 1930s. Honest 103dB SPL/1W 4' speakers filled large theaters with 20 watts of naked push-pull triode.
Get copies of F. Langford-Smith's (Aussie like you) Radiotron Designer books. It is very enlightening to compare the 3rd edition (1930s) with the more famous 4th edition (1946). That 3rd edition explains all the reasons audio has been mostly downhill, though L-S phrases it carefully: his employers were leading the downhill charge. Beam-Power gives higher Watt numbers per dollar and allows more cheap radios to be sold, more tube sales. Beam-power can be nasty: Negative feedback can make it less nasty, at least by the numbers. (RDM 4th casts great doubt on THD numbers, a lesson not learned for another 50 years.)
> how much development has there been in the 40 years since then?
http://worldebible.com/ecclesiastes/1.htm
Ecclesiastes, The words of the Preacher, the son of David
Not appealing to religion.... this passage is basic existentialist philosophy with a few nods to some God on the side.
Some small improvements. Sand-state makes many tube-things easier, and possibly "better". I would not use tubes any more if I had to use hollow-state rectifiers (others disagree).
But they knew what they were doing when the world revolved around tubes. Talking movie systems were very advanced in the 1930s. Honest 103dB SPL/1W 4' speakers filled large theaters with 20 watts of naked push-pull triode.
Get copies of F. Langford-Smith's (Aussie like you) Radiotron Designer books. It is very enlightening to compare the 3rd edition (1930s) with the more famous 4th edition (1946). That 3rd edition explains all the reasons audio has been mostly downhill, though L-S phrases it carefully: his employers were leading the downhill charge. Beam-Power gives higher Watt numbers per dollar and allows more cheap radios to be sold, more tube sales. Beam-power can be nasty: Negative feedback can make it less nasty, at least by the numbers. (RDM 4th casts great doubt on THD numbers, a lesson not learned for another 50 years.)
> how much development has there been in the 40 years since then?
http://worldebible.com/ecclesiastes/1.htm
Ecclesiastes, The words of the Preacher, the son of David
Not appealing to religion.... this passage is basic existentialist philosophy with a few nods to some God on the side.
I would say (with the exception of speakers)that decent quality modern electronics is not better than 40 years ago, it is worse.>
Well, Kent - I catch your general drift, but there are some loopholes to this. I have a Leak Stereo 20 amp which is exactly 40 years old. Since then I've rebuilt it several times with more evolved circuits and parts. Out went original parts, in came Holco resistors and teflon caps. Parts definitely better these days. Out went electolytics in the PSU, in came motor run polypropylenes - a new part. Out went ECC83s with loads of feedback, in came 6N1P front end with no global feedback. Out went the pentode outputs that were all the rage 40 years ago, in came an all triode output stage with 6S4A (yep, that's history!) Out went cathode resistors, in came a CCS with solid state devices. This amp in its present state is so HUGELY better than the original it's laughable.
Call it evolution or fashion, the fact is that with what we have at our disposal (including the Internet for rapid exchange of complex ideas over several continents) we do have the means to make considerably improved audio componants. But as you say, it's a whole other question whether manufacturers actually build better componants, because if electronics has progressed, the art of selling, spin, making money and influencing people has probably progressed even more rapidly, together with the mountains and mountains of detritus created by this fast-sell throwaway modern world. Andy
Well, Kent - I catch your general drift, but there are some loopholes to this. I have a Leak Stereo 20 amp which is exactly 40 years old. Since then I've rebuilt it several times with more evolved circuits and parts. Out went original parts, in came Holco resistors and teflon caps. Parts definitely better these days. Out went electolytics in the PSU, in came motor run polypropylenes - a new part. Out went ECC83s with loads of feedback, in came 6N1P front end with no global feedback. Out went the pentode outputs that were all the rage 40 years ago, in came an all triode output stage with 6S4A (yep, that's history!) Out went cathode resistors, in came a CCS with solid state devices. This amp in its present state is so HUGELY better than the original it's laughable.
Call it evolution or fashion, the fact is that with what we have at our disposal (including the Internet for rapid exchange of complex ideas over several continents) we do have the means to make considerably improved audio componants. But as you say, it's a whole other question whether manufacturers actually build better componants, because if electronics has progressed, the art of selling, spin, making money and influencing people has probably progressed even more rapidly, together with the mountains and mountains of detritus created by this fast-sell throwaway modern world. Andy
andyjevans said:
Don't give up......I'm an optimist regarding tubes........discrete components have improved........electrolytics better and power resistors much more reliable than all those wax components of yesteryear. Tube quality OMO has gone downhill, in that I'm designing circuits with way lower b+ voltages and using parallel output stages to get the power up with reliability. Back in the late 60's it was common to see KT88's and 6550A's running at 600V at 60mA quies......I wouldn't dare run todays made tubes at that voltage today.
I don't understand why the ceased highly popular 6550A hasn't been re-introduced ....clone manufacturers only introduced other versions which have to run derated. A marketing opportunity missed. Anyone in the trade would rated as completely absurd the intro of the KT100....really a reglassed 88. WHo really needs a tube like this ? MOV even reconed the KT88 was too heavy for the base holder.... so why the craving ?
The trade was saying in the late 80's that the mosfet will superceed the transistor.......25 yrs onwards not so.
output transformers have improved .....winding physics is now way better.....but the iron hasn't changed........perhaps more exotic mixes.
richj
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