DHT heater regulation
That is relatively incorrect and quite disputable.
Let us assume that you really have spent xxx USD for those 300Bs. That does most probably make you a further "client" i.e. marketing victim. Why? Because someone explainst to you that regulation will lengthen the life of your "precious" DHTs. What they (you) forgot to mention is whether it is current or voltage regulation?
If your mains varies 10%, your secondary would also vary 10%, basically. This means 5.5V instead of 5V. Not that much of a problem, actually, since they all tend to sound better (to me) at approx. 10% higher heater voltage.
Reduced life, at that? Depends on how much reduced. If it is 25-50%, than maybe it does matter. But it is not that much, and it does not. What matters is that you get the bang for your BUCK, i.e. when you buy a Porsche you do not use it to stroll to the green market, but to drive it as fast and exciting as possible (on deserted roads, or on racing tracks, not to endanger others, or your drivers license).
Furthermore, I am surprised that you have that many problems in the US with voltage variation, for such a wealthy country
I tought it was just a problem of ours during the sanctions period in the 90's?!
Last, but not least: what happens with your tube if the regulator stops working? Or, if it works incorrectly (i.e. current regulator that starts drawing huge amounts of current thru the "precious" 300B). The chance of a SS regulator crashing are higher than the risk you take with the mains voltage variations...
That is relatively incorrect and quite disputable.
Let us assume that you really have spent xxx USD for those 300Bs. That does most probably make you a further "client" i.e. marketing victim. Why? Because someone explainst to you that regulation will lengthen the life of your "precious" DHTs. What they (you) forgot to mention is whether it is current or voltage regulation?
If your mains varies 10%, your secondary would also vary 10%, basically. This means 5.5V instead of 5V. Not that much of a problem, actually, since they all tend to sound better (to me) at approx. 10% higher heater voltage.
Reduced life, at that? Depends on how much reduced. If it is 25-50%, than maybe it does matter. But it is not that much, and it does not. What matters is that you get the bang for your BUCK, i.e. when you buy a Porsche you do not use it to stroll to the green market, but to drive it as fast and exciting as possible (on deserted roads, or on racing tracks, not to endanger others, or your drivers license).
Furthermore, I am surprised that you have that many problems in the US with voltage variation, for such a wealthy country
I tought it was just a problem of ours during the sanctions period in the 90's?!Last, but not least: what happens with your tube if the regulator stops working? Or, if it works incorrectly (i.e. current regulator that starts drawing huge amounts of current thru the "precious" 300B). The chance of a SS regulator crashing are higher than the risk you take with the mains voltage variations...
INNOVATIVE MARKETING!!!
I do not believe this!!! I would say the post is WAY out of context, BECAUSE this is a thread about innovations in tube amps, nor about innovations in tube amp marketing ploys!!!
On the other hand, it can serve to illustrate where is the MODERN TUBE AMP story actually going to end.
If you were not happy with KT88 amps (and you could tell us why), you might be happy with my RH88 design. I guarantee you that you will be happy. Actually, there is no money back guarantee, because it is for FREE, and thus it does not have to pay for marketing. Or is it the marketing that facilitates the sales?
If you are not satisfied with just some amp without innovation, take another look and try to imagine that the design was actually given to me by aliens when I was abducted (the penultimate time, not the last time -- as the last time they were teaching me how to use the soldering iron creatively to make amps).
I do not believe this!!! I would say the post is WAY out of context, BECAUSE this is a thread about innovations in tube amps, nor about innovations in tube amp marketing ploys!!!
On the other hand, it can serve to illustrate where is the MODERN TUBE AMP story actually going to end.
If you were not happy with KT88 amps (and you could tell us why), you might be happy with my RH88 design. I guarantee you that you will be happy. Actually, there is no money back guarantee, because it is for FREE, and thus it does not have to pay for marketing. Or is it the marketing that facilitates the sales?
If you are not satisfied with just some amp without innovation, take another look and try to imagine that the design was actually given to me by aliens when I was abducted (the penultimate time, not the last time -- as the last time they were teaching me how to use the soldering iron creatively to make amps).
Re: INNOVATIVE MARKETING!!!
Aren't you a little quick to judge? Have you ever looked at the website? DIY stuff all over the place - I have paid by dues. As for marketing, I am just a little guy who is known fairly wide as a person who has a passion for what I do. Leave the marketing hype to Sony, Sanyo et al. But I suppose there always has to be a first, but being accused of inventing marketing hype (and one's efforts totally demeaned in a flash statement) is a bit beyond the pale. As for tube (and other) innovations, I have actually been recognised here and there for a few (I have sold LEM modules to DIY guys), and also for promoting affordable high-end audio. Many phone calls from DIY guys here in Australia and from overseas, and often just helping them along. Hardly marketing.
Read the website, I think you might change your mind. How about spending a thousand hours on a large scale DIY loudspeaker project and posting all the details and making a pittance from it?
BTW, many who contact me read these forums but don't have the ability to do what you guys do and maybe even a little envious. They only contribute a comment here or there, but they talk to me and ask for my help. The Tube Gainclone started off like that. The whole idea of buffering (with a tube preferred but not exclusively) inverted gainclones was back in 2002-3 and whose idea was that? Have you heard of the Super Linear Cathode Follower? Not marketing hype as the schematics are available online - and copied now by others. Those are but just a couple of things...
I think I have paid my dues!
Cheers.
Joe R.
PS: Why does some think that everything revolves money and that success in life is based on size of a paypacket (being a good housewife earning nothing can still be counted as a success). Maybe I should show you my tax return for last year. You might be surprised but I barely manage to go beyond breaking even (much gets folded back into making more things possible). But I have a lot of support and after many years and not getting any younger, I decided to do what I want to do. I get a lot of satisfaction and would you believe that old commodity, friends. They appreciate the value I offer.
Alex Kitic said:
Aren't you a little quick to judge? Have you ever looked at the website? DIY stuff all over the place - I have paid by dues. As for marketing, I am just a little guy who is known fairly wide as a person who has a passion for what I do. Leave the marketing hype to Sony, Sanyo et al. But I suppose there always has to be a first, but being accused of inventing marketing hype (and one's efforts totally demeaned in a flash statement) is a bit beyond the pale. As for tube (and other) innovations, I have actually been recognised here and there for a few (I have sold LEM modules to DIY guys), and also for promoting affordable high-end audio. Many phone calls from DIY guys here in Australia and from overseas, and often just helping them along. Hardly marketing.
Read the website, I think you might change your mind. How about spending a thousand hours on a large scale DIY loudspeaker project and posting all the details and making a pittance from it?
BTW, many who contact me read these forums but don't have the ability to do what you guys do and maybe even a little envious. They only contribute a comment here or there, but they talk to me and ask for my help. The Tube Gainclone started off like that. The whole idea of buffering (with a tube preferred but not exclusively) inverted gainclones was back in 2002-3 and whose idea was that? Have you heard of the Super Linear Cathode Follower? Not marketing hype as the schematics are available online - and copied now by others. Those are but just a couple of things...
I think I have paid my dues!
Cheers.
Joe R.
PS: Why does some think that everything revolves money and that success in life is based on size of a paypacket (being a good housewife earning nothing can still be counted as a success). Maybe I should show you my tax return for last year. You might be surprised but I barely manage to go beyond breaking even (much gets folded back into making more things possible). But I have a lot of support and after many years and not getting any younger, I decided to do what I want to do. I get a lot of satisfaction and would you believe that old commodity, friends. They appreciate the value I offer.
Joe, you have no need to be defensive, res ipsa loquitur and all that.
Some of the comments remind me of an amusing run-in I had with, umm, let me just say "a very well-known British designer originally from South Africa." I was at breakfast, reviewing my phono preamp design with a couple of friends when he walked by, glanced at the schematics we were looking at, and without even a "Good Morning!" jabbed his finger at the page in my notebook and exclaimed, "This design is a piece of @#&%!" Being a difficult person to offend and always willing to learn, I merely asked, "What's wrong with it?" The Famous Guy jabs his finger at the schematic again, this time hitting the FET CCS plate loads and hissing, "These! These! There weren't any FETs available in the 1930s or 1940s!" One of my breakfast companions, a rather diffident Brit, responded quietly, "Errrr, you might notice that it's 2007..."
Some of the comments remind me of an amusing run-in I had with, umm, let me just say "a very well-known British designer originally from South Africa." I was at breakfast, reviewing my phono preamp design with a couple of friends when he walked by, glanced at the schematics we were looking at, and without even a "Good Morning!" jabbed his finger at the page in my notebook and exclaimed, "This design is a piece of @#&%!" Being a difficult person to offend and always willing to learn, I merely asked, "What's wrong with it?" The Famous Guy jabs his finger at the schematic again, this time hitting the FET CCS plate loads and hissing, "These! These! There weren't any FETs available in the 1930s or 1940s!" One of my breakfast companions, a rather diffident Brit, responded quietly, "Errrr, you might notice that it's 2007..."
SY said:
Thanks Stuart.
SY said:
You forget, I was there.
Allen recounts a similar experience with him, but it was in an elevator (London Hi-Fi show) that he met first him, introduced himself and tried to say hello. Just didn't get a rise from him, despite the fact we have a mutual Australian friend, Max Townshend, but that means nothing to him. Max knows how touchy he is, but is able to stroke him the right way. The key, get him to talk about cars, especially vintage Brit cars and motors. Then you can't stop him.
SY said:
Good one, late 2006 I recall. Not Morgan you-know-who? Sounds like him. But I can tell you, the strange one does not like current sources. Can't recall the exact reason.
Hey, this guessing names is kinda fun?
Joe R.
Here is an example of a "Modern Tube Amplifier".
There are enough elements here to feed a lively discussion?
While the schematic is a simplified version and I have not given specific component values, it is hardly necessary - they would largely be fairly standard anyway or dependant on the amplifier. I wouldn't (and rarely do) build this from scratch, but rather customise suitable amplifiers which are largely based on stuck-in-the-fifties technology.
Joe R.
An externally hosted image should be here but it was not working when we last tested it.
There are enough elements here to feed a lively discussion?
While the schematic is a simplified version and I have not given specific component values, it is hardly necessary - they would largely be fairly standard anyway or dependant on the amplifier. I wouldn't (and rarely do) build this from scratch, but rather customise suitable amplifiers which are largely based on stuck-in-the-fifties technology.
Joe R.
a line in the sand.............re 2nd posting
The negative feedback amplifier was invented by Harold Stephen Black at Bell Laboratories in 1927 (over 80 years ago)
you may also think that directly heated tubes are old hat
but in the late 1970s and onwards new dht's were designed that can leave any blow torch standing .............!
so much so that a blow torch amp sounds more like mud than sand
The negative feedback amplifier was invented by Harold Stephen Black at Bell Laboratories in 1927 (over 80 years ago)
you may also think that directly heated tubes are old hat
but in the late 1970s and onwards new dht's were designed that can leave any blow torch standing .............!
so much so that a blow torch amp sounds more like mud than sand
One innovation that happened in tube amps has been the OTL. In the 50s, the Futterman was the only game in town in OTLs. Nowadays most OTLs use a Circlotron output, symmetrically driven by a fully differential driver.
This type of amplifier did not exist before 1985 or thereabouts.
Further innovations include the use of 2-stage CCS circuits in the differential voltage amplifier and direct-coupled driver circuits, automatic bias and servo-controlled DC levels at the output.
Such amplifiers are **also** the 'Best Sounding in the World'...
If we are going to discuss innovation, it would be a very incomplete discussion to omit David Berning and his accomplishments. Although he and I have disagreed in the past as to whether his amplifier is an OTL, the simple fact of the matter is that he has developed a very innovative amplifier that also gets around many of the traditional issues of OPTs.
This type of amplifier did not exist before 1985 or thereabouts.
Further innovations include the use of 2-stage CCS circuits in the differential voltage amplifier and direct-coupled driver circuits, automatic bias and servo-controlled DC levels at the output.
Such amplifiers are **also** the 'Best Sounding in the World'...
If we are going to discuss innovation, it would be a very incomplete discussion to omit David Berning and his accomplishments. Although he and I have disagreed in the past as to whether his amplifier is an OTL, the simple fact of the matter is that he has developed a very innovative amplifier that also gets around many of the traditional issues of OPTs.
Leaving OTLs aside, as this a topic which I haven't looked much into, there seems to be a consensus that PSU sag is unwanted, as well as poor regulation and noise in any part of a supply circuit.
This is probably possible with both technologies, but economically and weight wise it is probably a lot easier to implement using SS. This probably also goes for CCSs, which a lot of people find very beneficial. Thus it seems quite contradictory to deny the advantages of using SS for certain tasks.
As far as I can see, the advantages of tube amps lies in the tube itself as a signal amplifier. This will forever be as old as the tube itself, as long as no new magic tubes are developed. Fighting the use of SS in other stages of a tube amp seems just like walking backwards ito the future. Some may even say fanatical , - or maybe hysterical..?
If such as design makes it "less pure" as a tube amp , who cares ?
( except the fanatics )
Keep up the good work , guys
This is probably possible with both technologies, but economically and weight wise it is probably a lot easier to implement using SS. This probably also goes for CCSs, which a lot of people find very beneficial. Thus it seems quite contradictory to deny the advantages of using SS for certain tasks.
As far as I can see, the advantages of tube amps lies in the tube itself as a signal amplifier. This will forever be as old as the tube itself, as long as no new magic tubes are developed. Fighting the use of SS in other stages of a tube amp seems just like walking backwards ito the future. Some may even say fanatical , - or maybe hysterical..?
If such as design makes it "less pure" as a tube amp , who cares ?
( except the fanatics )
Keep up the good work , guys
I tend to avoid threads when the emotion level gets turned up, but I have a few observations to add.
The thread originator asked the following:
These requirements define an amplifier that will be fairly complex. I know of one design that fills the bill, but in the words of the designer, "Brace yourself for a tour de force of amplifier design. It's arguably the most sophisticated vacuum tube amplifier ever. But be forewarned if you plan to build it: It's not a simple project. Absolutely not for beginners!" Look Here:
http://www.normankoren.com/Audio/TENA.html
With respect to number 3 above, the DSP in my design was part of the requirements for the design contest, but it did perform a very real function. I was measuring a plate efficiency of over 60% in a single ended vacuum tube amplifier. The signal path is 100% pure tube. The high efficiency is achieved by using DSP to modulate the supply voltage as is done in solid state class H designs. Personal circumstances have prevented any further development of this design, in fact I have built NO amplifiers since this one. Interested people can download the entire project submission here:
http://www.circuitcellar.com/microchip2007/winners/MT2209.html
With respect to number 2 above, true most "modern hybrid" designs are simply a tube buffer or gain stage driving the typical class AB solid state output stage. These sound too much like a solid state amp to me. It is possible to build a hybrid design based on a tube amplifier with a hybrid "darlington like" output stage that uses a tube for voltage gain and a mosfet for current gain (or "boost"). It can be a SE or push pull design that still uses an output transformer. This combinatination sounds very tube like.
I agree, where is the "modern"? The design itself has been around for a while.
So, if there is any sand in the amp, it is not a tube amp? As stated tubes are OLD. The ones in my current Tubelab SE are 78 years old and still sound nice. I can't say for sure (since I wasn't there in 1931) but I believe that they sound far better in my "modern" design with supporting silicon than they did in the old Sparton radio that I pulled them out of. To me the Tubelab SE is a tube amp, but you can call it whatever you want.
I didn't want to believe this, but now I am beginning to think that it is true, with a few exceptions. Granted this IS 2009, and we now have far more component choices than were available in the vacuum tube era. Granted many of them are "semiconductors" (not necessarilly silicon), and some may choose to exclude them from tube amplifier designs.
There have been a few times when I thought that I had discovered a new "pure tube" concept, but once I posted it, sure enough it had been done before, usually long before. I thought I was on to something when I was working on the DSP based amplifier when I discovered how linear a cathode follower could be if the voltage across it, and the current through it was held constant. I thought that I had found something new.
The Super Linear Cathode Follower is credited to Allen Wright and Joe Rasmussen. It is very similar to the concept that I "discovered". Both cool "new" ideas? Nope. Discovered and patented by Ross Macdonald in 1957. See this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114021&highlight=
Now, I took this concept a bit further and built a big augmented cathode follower output stage. It ROCKS, but is it "modern"? Is it, like the OTL's, new and unique? Is it a tube amp since is contains zener diodes, and possibly a CCS chip?
The subject of DC heating on DHT's comes up over and over again. As with EVERYTHING in this hobby each is entitled to their own opinion. In my experience there is yet another reason for DC. During the development of the Tubelab SE I spent some time chasing down a haziness to the sound. I was using a well balanced AC supply on the 45 tube with the residual hum nulled to below audibility. The sound coloration turned out to be IMD (found with FFT) products of the 60 Hz filament voltage on either side of the signal. These are signal level dependent, and seem to be generated entirely in the tube itself. Of course they do not occur with DC. To me the amp sounds cleaner and less fatiguing with DC filament power, but others have formed exactly the opposite opinion.
The thread originator asked the following:
These requirements define an amplifier that will be fairly complex. I know of one design that fills the bill, but in the words of the designer, "Brace yourself for a tour de force of amplifier design. It's arguably the most sophisticated vacuum tube amplifier ever. But be forewarned if you plan to build it: It's not a simple project. Absolutely not for beginners!" Look Here:
http://www.normankoren.com/Audio/TENA.html
With respect to number 3 above, the DSP in my design was part of the requirements for the design contest, but it did perform a very real function. I was measuring a plate efficiency of over 60% in a single ended vacuum tube amplifier. The signal path is 100% pure tube. The high efficiency is achieved by using DSP to modulate the supply voltage as is done in solid state class H designs. Personal circumstances have prevented any further development of this design, in fact I have built NO amplifiers since this one. Interested people can download the entire project submission here:
http://www.circuitcellar.com/microchip2007/winners/MT2209.html
With respect to number 2 above, true most "modern hybrid" designs are simply a tube buffer or gain stage driving the typical class AB solid state output stage. These sound too much like a solid state amp to me. It is possible to build a hybrid design based on a tube amplifier with a hybrid "darlington like" output stage that uses a tube for voltage gain and a mosfet for current gain (or "boost"). It can be a SE or push pull design that still uses an output transformer. This combinatination sounds very tube like.
I agree, where is the "modern"? The design itself has been around for a while.
So, if there is any sand in the amp, it is not a tube amp? As stated tubes are OLD. The ones in my current Tubelab SE are 78 years old and still sound nice. I can't say for sure (since I wasn't there in 1931) but I believe that they sound far better in my "modern" design with supporting silicon than they did in the old Sparton radio that I pulled them out of. To me the Tubelab SE is a tube amp, but you can call it whatever you want.
I didn't want to believe this, but now I am beginning to think that it is true, with a few exceptions. Granted this IS 2009, and we now have far more component choices than were available in the vacuum tube era. Granted many of them are "semiconductors" (not necessarilly silicon), and some may choose to exclude them from tube amplifier designs.
There have been a few times when I thought that I had discovered a new "pure tube" concept, but once I posted it, sure enough it had been done before, usually long before. I thought I was on to something when I was working on the DSP based amplifier when I discovered how linear a cathode follower could be if the voltage across it, and the current through it was held constant. I thought that I had found something new.
The Super Linear Cathode Follower is credited to Allen Wright and Joe Rasmussen. It is very similar to the concept that I "discovered". Both cool "new" ideas? Nope. Discovered and patented by Ross Macdonald in 1957. See this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114021&highlight=
Now, I took this concept a bit further and built a big augmented cathode follower output stage. It ROCKS, but is it "modern"? Is it, like the OTL's, new and unique? Is it a tube amp since is contains zener diodes, and possibly a CCS chip?
The subject of DC heating on DHT's comes up over and over again. As with EVERYTHING in this hobby each is entitled to their own opinion. In my experience there is yet another reason for DC. During the development of the Tubelab SE I spent some time chasing down a haziness to the sound. I was using a well balanced AC supply on the 45 tube with the residual hum nulled to below audibility. The sound coloration turned out to be IMD (found with FFT) products of the 60 Hz filament voltage on either side of the signal. These are signal level dependent, and seem to be generated entirely in the tube itself. Of course they do not occur with DC. To me the amp sounds cleaner and less fatiguing with DC filament power, but others have formed exactly the opposite opinion.
Xenu, you quote yourself as a tube newbie. Norman Koren's amp is an example of how much sand you can throw at it.. If you don't like it, then you have to re-define it your target spec.. like any commercial proposal.
You can make an excellent top notch sounding conventional Hi-fi amp, top notch SS regulated psu with no sag (unless for MI) and design using FFT analysis to weed out the intolerable sounding harmonics. All of these tools are now possible at reasonable cost and without brain imploding.
Re read Morgan Jones books. As an SMPS/ RF engineer, it made me re-think down to earth the simplicity of tubes.
richy
You can make an excellent top notch sounding conventional Hi-fi amp, top notch SS regulated psu with no sag (unless for MI) and design using FFT analysis to weed out the intolerable sounding harmonics. All of these tools are now possible at reasonable cost and without brain imploding.
Re read Morgan Jones books. As an SMPS/ RF engineer, it made me re-think down to earth the simplicity of tubes.
richy
richwalters said:
You hit the nail on the head with that one. That book is what inspired me to go beyond the one amp that I happened to have (long story) and distilled tube design down to a level that I could wrap my head around. I think I was flipping through the 1st ed in a library or somewhere and went out and bought the 2nd ed the very next day (had to special order it).
We learned how to bias transistors in college, intermixed with gobs of theory that in the end is not all that useful. I don't think I *really* understood what was going on in such circuits until I designed my own tube circuits with the help of that book. How ironic is that? I don't know, but he explained things in a practical way that I could really understand and put to use.
As to "modern" designs...I think that is in the eye of the beholder. Mind over matter and all that. If you are sufficiently opinionated about something, it is easy to "hear" things that correlate strongly to those opinions. There are also historical factors about what sounds "right" to the individual. I grew up listening to everything through a medium-fi tube amp, so I'm sure that affects my view of what sounds "right".
Russ
While I do not doubt the sonic qualities of your Tubelab SE which you have painstakingly designed and developed to the point of finding IMD residuals from 60Hz AC on the heaters (frankly, we say sic! to that, but I admire the length you went) -- I am sorry to see nice globe 45s used with MOSFETs, as if there were no nice tubes to drive those nice 45s (yes, you got it -- I do not own any 45s)...
Fun aside, your amp is a hybrid amp. If it was using just tubes in the signal path (strictly speaking) it would be a tube amp. If it were not using tubes, it would be a "transistor" amp. Since it uses both, it is a hybrid amp. There is nothing bad or offensive to that simple truth. Maybe it is politically incorrect, or maybe you could call me a tube rasist.
Before you think or say any of that, let me tell you that I used to design with opamps before designing with tubes. I actually learned everything the wrong way around
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.