I've been on this forum for a very short period of time compared with many of you guys!
I'm trying to get a better handle of this "technology" and......the quote to quote....takes me into the real topic of this post:
by checking the posts for newbies....i have downloaded and selected the informations that i need to increase my kwnoledge over this subject.
After awhile, i have stopped and reflect over this:
The whole source, i've found so far on Internet, is from the early 1950 or so...and the question it's a real consequence of this fact:
Is there any new thing on the valves design NOW (i'm talking about the last 15-20 years) that wasn't still discovered by then?
The modern valve equipments are still using the same schematics developed in the 50's -60's or even erlier (40's) ?
That is a question that i think most of the newbies would put to themeselves....because.....you see this source of information and you wonder if you have to study them or you have drop or skip them to pass for a better up-to-date source!
i hope you guys can help me to understand this point!
Thank's in advance.
Best Regards,
Stefano.
I'm trying to get a better handle of this "technology" and......the quote to quote....takes me into the real topic of this post:
by checking the posts for newbies....i have downloaded and selected the informations that i need to increase my kwnoledge over this subject.
After awhile, i have stopped and reflect over this:
The whole source, i've found so far on Internet, is from the early 1950 or so...and the question it's a real consequence of this fact:
Is there any new thing on the valves design NOW (i'm talking about the last 15-20 years) that wasn't still discovered by then?
The modern valve equipments are still using the same schematics developed in the 50's -60's or even erlier (40's) ?
That is a question that i think most of the newbies would put to themeselves....because.....you see this source of information and you wonder if you have to study them or you have drop or skip them to pass for a better up-to-date source!
i hope you guys can help me to understand this point!
Thank's in advance.
Best Regards,
Stefano.
There certainly are new implementations, improving on things like noise rejection etc, look at the aikido for instance...
Ultimatly valves are very passive components it would seem (btw I'm also a noob, but an opinianated one). all they care about is the voltages, currents and impendances their respective pins see generaly. So its open to anyone to use whatever solidstate/integrated circuit to manage these attributes.
However you would still need to be familiar with what the old passive component arrangements were doing to begin to improve on them. So learning the old stuff is nearly inevitable.
I think on the other hand with minituarisation trends, it would be hard to find enough suitably rated components in the near future, wich would bring you right back to basics, using pasive components.
Ultimatly valves are very passive components it would seem (btw I'm also a noob, but an opinianated one). all they care about is the voltages, currents and impendances their respective pins see generaly. So its open to anyone to use whatever solidstate/integrated circuit to manage these attributes.
However you would still need to be familiar with what the old passive component arrangements were doing to begin to improve on them. So learning the old stuff is nearly inevitable.
I think on the other hand with minituarisation trends, it would be hard to find enough suitably rated components in the near future, wich would bring you right back to basics, using pasive components.
(Fireproof suit on) 
Valve guys don't seem to like anything new. You only have to look at the deathly silence that follows the mention of something like solid state regulation to see that. Let alone something like SY's Heretical Line Stage, (one of the best preamps I have ever heard), that has an opamp servo as well!
Valve guys don't seem to like anything new. You only have to look at the deathly silence that follows the mention of something like solid state regulation to see that. Let alone something like SY's Heretical Line Stage, (one of the best preamps I have ever heard), that has an opamp servo as well!
i'm not talking about valve guys or audience.
I'm referring of new type of shematichs, differente uses of the valve instead of the 10-12 c classic schematic.
I don't know....i'm totally guessing...... for instance...... the noise cancellation....if i'm not wrong was already developed on the 50's (around that!)
I mean...if i want to be a professional valve's projecter....do i have to study JUST the old books that i see on the net...or should i up-to-date my kwnoledge with something new.
I'm an engineer and it's a shame for me to study books that have more then the double of my age!
For instance...if i would study the digital technology on books from 90's...everybody would laugh at me....that's the concept that i'm tring to explain.
I would like to know if something new has come around ...at least...in the last 20years.
Is it possible that the research on valves's use it's already gotten to its climax a long time ago??
New patent....new use of the valve.....and so on??
Hope to clearify this point!
Thanks.
Stefano.
I'm referring of new type of shematichs, differente uses of the valve instead of the 10-12 c classic schematic.
I don't know....i'm totally guessing...... for instance...... the noise cancellation....if i'm not wrong was already developed on the 50's (around that!)
I mean...if i want to be a professional valve's projecter....do i have to study JUST the old books that i see on the net...or should i up-to-date my kwnoledge with something new.
I'm an engineer and it's a shame for me to study books that have more then the double of my age!
For instance...if i would study the digital technology on books from 90's...everybody would laugh at me....that's the concept that i'm tring to explain.
I would like to know if something new has come around ...at least...in the last 20years.
Is it possible that the research on valves's use it's already gotten to its climax a long time ago??
New patent....new use of the valve.....and so on??
Hope to clearify this point!
Thanks.
Stefano.
As you say, classic circuits were developed and have stood the test of time. There are some differences between old and modern circuits...
(1) In real terms, valves are cheaper now than in the 50s. As a consequence modern circuits don't need to wring every last bit of gain out of a valve and if another valve would help, it is used.
(2) Low distortion sources are widely available, so amplifier noise and distortion are expected to be lower. This has tended to drive operating currents in pre-amplifiers and driver stages higher.
(3) Modern resistors and capacitors are far better. As one example, this has enabled tolerances in equalisation to be tightened up - it has also meant that design errors in equalisation can no longer be tolerated.
(4) Computers. Classic circuits were designed using a slide rule, but a computer can be used to model the circuit at the design stage then measure and analyse results at the prototype stage. FFT analysis has enabled home investigation that wouldn't even have been possible in a laboratory in the 50s.
The Internet has broadened the choice of components available at the design stage. Traditional designs used components from one country, but a modern design might use a British special quality valve, an American TV valve, and a German telecommunications valve. The same argument applies to passive components, Soviet PTFE capacitors from the Cold War are popular - definitely not available in the 50s!
(5) Semiconductors. Modern circuits can incorporate semiconductors when it seems useful. Mostly, this tends to be in power supplies, but they're also common in constant current sinks.
(6) Oscilloscopes. In the 50s, an oscilloscope was a rare beast but a 20MHz dual channel oscilloscope is now peanuts. This has meant that modern designs have far more attention paid to HF stability.
(1) In real terms, valves are cheaper now than in the 50s. As a consequence modern circuits don't need to wring every last bit of gain out of a valve and if another valve would help, it is used.
(2) Low distortion sources are widely available, so amplifier noise and distortion are expected to be lower. This has tended to drive operating currents in pre-amplifiers and driver stages higher.
(3) Modern resistors and capacitors are far better. As one example, this has enabled tolerances in equalisation to be tightened up - it has also meant that design errors in equalisation can no longer be tolerated.
(4) Computers. Classic circuits were designed using a slide rule, but a computer can be used to model the circuit at the design stage then measure and analyse results at the prototype stage. FFT analysis has enabled home investigation that wouldn't even have been possible in a laboratory in the 50s.
The Internet has broadened the choice of components available at the design stage. Traditional designs used components from one country, but a modern design might use a British special quality valve, an American TV valve, and a German telecommunications valve. The same argument applies to passive components, Soviet PTFE capacitors from the Cold War are popular - definitely not available in the 50s!
(5) Semiconductors. Modern circuits can incorporate semiconductors when it seems useful. Mostly, this tends to be in power supplies, but they're also common in constant current sinks.
(6) Oscilloscopes. In the 50s, an oscilloscope was a rare beast but a 20MHz dual channel oscilloscope is now peanuts. This has meant that modern designs have far more attention paid to HF stability.
I'd emphasize EC's point 5. We can use solid state to set operating points and do circuit housekeeping in ways the guys in the '50s couldn't.
For example, a proper current-sink for a long-tail pair was a significant problem in 1956 (requiring an extra tube, an extra power supply rail, and an extra heater supply), which is why they were used in approximately zero power amp phase splitters at that time. A couple of transistors and LEDs or a couple of depletion mode MOSFETs accomplish that function today for about 2 bucks and 3-4 square centimeters. So in 2006, we can easily build a phase splitter with far better balance than we could in 1956.
Or take the notorious servo that pinkmouse mentioned: we can direct-couple from the output of a cathode follower without running the signal through a big, messy capacitor using an opamp and a handful of small Rs and Cs. The servo handles nothing but DC to 1-2 Hz, freeing the tube to do its thing properly.
And regulation- we can do triode amplifiers with far less dynamic distortion these days by regulating the B+. In theory, that could have been done in 1950, but it would require a regulator four times the size and expense of the amp. So even for the "classic" amps, it just wasn't used. The B+ regulator in my small triode amp (20W) is about the size of my fist and cost less than $10. The transistors only handle DC and subsonics. The tubes are left to run optimally.
In terms of tube topologies, there's a limited number of ways to connect them, and they were all done by 1960. Now, most topologies weren't used in audio, but creative guys like John Broskie are trying to remedy that.
For example, a proper current-sink for a long-tail pair was a significant problem in 1956 (requiring an extra tube, an extra power supply rail, and an extra heater supply), which is why they were used in approximately zero power amp phase splitters at that time. A couple of transistors and LEDs or a couple of depletion mode MOSFETs accomplish that function today for about 2 bucks and 3-4 square centimeters. So in 2006, we can easily build a phase splitter with far better balance than we could in 1956.
Or take the notorious servo that pinkmouse mentioned: we can direct-couple from the output of a cathode follower without running the signal through a big, messy capacitor using an opamp and a handful of small Rs and Cs. The servo handles nothing but DC to 1-2 Hz, freeing the tube to do its thing properly.
And regulation- we can do triode amplifiers with far less dynamic distortion these days by regulating the B+. In theory, that could have been done in 1950, but it would require a regulator four times the size and expense of the amp. So even for the "classic" amps, it just wasn't used. The B+ regulator in my small triode amp (20W) is about the size of my fist and cost less than $10. The transistors only handle DC and subsonics. The tubes are left to run optimally.
In terms of tube topologies, there's a limited number of ways to connect them, and they were all done by 1960. Now, most topologies weren't used in audio, but creative guys like John Broskie are trying to remedy that.
it's exactly what i was talking about: the topology (which as you conferm me, was totally develoved by the end of 60s).
About the components, i agree with the fact that there are higher quality's components than back then due to the lower tolleraces and other factors.
About the OP amp i'm sory but i don't agree with you at all.
If we were solely talking about performances rather than sound i would do agree with you guys, but for me the target is the sound and not the wave form on an oscilloscope.
If an amp sounds great and have a great responce...then good...otherwise i could care less if an amplifier with havier components sound better than one made with op ampl but worse responce.
The op amp technology is smaller, cheaper and less noisy and so on than valves.
The point is that i'm noticing that you guys are likely to be not very considering about the sound, if i'm wrong you can correct me.
According to my experience, Amp with IC inside don't sound very nice and fine.
About the oscilloscope, the FFT, the simulators and so on....i completely agree.
Now it's easier and faster to develop a very good and stable amplifier with all this tools now avalable.
Regarding on the simulator, i will open in the future a 3d, since i have allegro cadence 15.5 and orcad 10.5 and would like to know if anybody uses this particular program.
Just one more thing:
whose John Broskie? (sorry for my ignorance!)
Best Regards,
Stefano.
About the components, i agree with the fact that there are higher quality's components than back then due to the lower tolleraces and other factors.
About the OP amp i'm sory but i don't agree with you at all.
If we were solely talking about performances rather than sound i would do agree with you guys, but for me the target is the sound and not the wave form on an oscilloscope.
If an amp sounds great and have a great responce...then good...otherwise i could care less if an amplifier with havier components sound better than one made with op ampl but worse responce.
The op amp technology is smaller, cheaper and less noisy and so on than valves.
The point is that i'm noticing that you guys are likely to be not very considering about the sound, if i'm wrong you can correct me.
According to my experience, Amp with IC inside don't sound very nice and fine.
About the oscilloscope, the FFT, the simulators and so on....i completely agree.
Now it's easier and faster to develop a very good and stable amplifier with all this tools now avalable.
Regarding on the simulator, i will open in the future a 3d, since i have allegro cadence 15.5 and orcad 10.5 and would like to know if anybody uses this particular program.
Just one more thing:
whose John Broskie? (sorry for my ignorance!)
Best Regards,
Stefano.
I would maintain that an op-amp based servo, which just handles DC-2Hz, will have far less impact on the sound than a 10uF coupling cap.
John Broskie is the proprietor of the excellent site www.tubecad.com .
John Broskie is the proprietor of the excellent site www.tubecad.com .
Many of the popular vacuum tube circuits have their roots in 1950's design. They are simple and work reasonably well when constructed with modern components. Make sure that you understand these designs before attempting anything more complex.
There is a large element of vacuum tube audiophiles that are resistant to change. Some of this is due to strong opinions voiced on other audio forums where new ideas that challenge the thinking of a few "gurus" is shunned. Some is also because of a lack of understanding of modern engineering and modelling tools. I see the same thing happening in big technology corporations. New ideas are often shunned because they force too many people to think in ways that they haven't done regardless of the circuitry or technology involved.
There is not much literature out there with new vacuum tube technology because there hasn't been any significant development work done in this area since the late 60's. The basics still hasn't changed. The popular old books will still teach you how a vacuum tube works. Study the Radiotron Designers Handbook, 4th edition. You can find the entire book available for download on the web.
Look here for this and other technical books:
http://www.pmillett.com/technical_books_online.htm
I have also found that engineering textbooks from the 1950's are also full of all of the vacuum tube technology that you would ever need. I have a book from MIT that is 80% advanced Calculus applied to vacuum tubes.
The Morgan Jones books are also good sources of old vacuum tube fundamentals from a modern perspective.
Once you understand the fundamentals of how tubes and the associated circuitry work, you can apply your engineering knowledge to them. There is no reason that you (or any other engineer) can't experiment and devise new topologies that use vacuum tubes alone, or with other modern components. Just don't expect any new circuitry to be adopted by the vacuum tube community overnight.
I published my PowerDrive circuit 3 years ago. It was immediately blasted in those other forums, and directly to me in e-mail. ALL of this criticism came from people who NEVER tried the circuit. I even got an e-mail saying that I should change my name from Tubelab to Transistorlab. As time went by a few brave souls actually tried the PowerDrive circuit, and liked it. They were vocal enough that more people tried it. I don't get hate mail any more, but most main stream tube audiophiles will never accept the circuit because it contains a MOSFET follower in the signal path.
A solid state device can be used with a vacuum tube, if careful thought is applied. True a transistor (or other device) can be very nonlinear if used as a gain stage. I don't think that there are too many people advocating this. There is no reason that a semiconductor can't be used as a buffer, or control loop (outside the audio path). If you do this you must understand that the solid state devices come up instantly, and vacuum tubes come up slowly. All operating conditions must be considered when mixing the two in the same circuit.
The following sites may be of some interest to those that are open to new ways of thinking with vacuum tubes. Keep in mind that some of the circuits on these sites may exist in the authors mind only. Some of them do not work, I have found this out by trying. If you want to design some new vacuum tube science, please share it with us, and be prepared to fry a few parts. Experiment on cheap stuff at first, and understand the safety precautions involved with high voltages.
www.tubecad.com Some circuits are just concepts, some do not work, some work excellent, the software works good, but is limited to single stages. The Akido circuitry is an example of new thinking applied to old vacuum tubes. I have not heard anyone say bad things about this design. I bought his boards, and built them. They do work well.
www.pmillett.com Many old books, some new tech, plenty interesting reading.
http://members.aol.com/sbench101/ No new information in a few years, but several circuits that no one else would try. Yes, new vacuum tube topologies. Some of them actually work!
www.tubelab.com My site. A few circuits, designs, and concepts. The ones that are labled "circuit concepts and ideas" have not been tested, and the stuff that isn't quite ready for prime time is labeled as such. New material is being added slowly. I have a full time engineering job.
There is a large element of vacuum tube audiophiles that are resistant to change. Some of this is due to strong opinions voiced on other audio forums where new ideas that challenge the thinking of a few "gurus" is shunned. Some is also because of a lack of understanding of modern engineering and modelling tools. I see the same thing happening in big technology corporations. New ideas are often shunned because they force too many people to think in ways that they haven't done regardless of the circuitry or technology involved.
There is not much literature out there with new vacuum tube technology because there hasn't been any significant development work done in this area since the late 60's. The basics still hasn't changed. The popular old books will still teach you how a vacuum tube works. Study the Radiotron Designers Handbook, 4th edition. You can find the entire book available for download on the web.
Look here for this and other technical books:
http://www.pmillett.com/technical_books_online.htm
I have also found that engineering textbooks from the 1950's are also full of all of the vacuum tube technology that you would ever need. I have a book from MIT that is 80% advanced Calculus applied to vacuum tubes.
The Morgan Jones books are also good sources of old vacuum tube fundamentals from a modern perspective.
Once you understand the fundamentals of how tubes and the associated circuitry work, you can apply your engineering knowledge to them. There is no reason that you (or any other engineer) can't experiment and devise new topologies that use vacuum tubes alone, or with other modern components. Just don't expect any new circuitry to be adopted by the vacuum tube community overnight.
I published my PowerDrive circuit 3 years ago. It was immediately blasted in those other forums, and directly to me in e-mail. ALL of this criticism came from people who NEVER tried the circuit. I even got an e-mail saying that I should change my name from Tubelab to Transistorlab. As time went by a few brave souls actually tried the PowerDrive circuit, and liked it. They were vocal enough that more people tried it. I don't get hate mail any more, but most main stream tube audiophiles will never accept the circuit because it contains a MOSFET follower in the signal path.
A solid state device can be used with a vacuum tube, if careful thought is applied. True a transistor (or other device) can be very nonlinear if used as a gain stage. I don't think that there are too many people advocating this. There is no reason that a semiconductor can't be used as a buffer, or control loop (outside the audio path). If you do this you must understand that the solid state devices come up instantly, and vacuum tubes come up slowly. All operating conditions must be considered when mixing the two in the same circuit.
The following sites may be of some interest to those that are open to new ways of thinking with vacuum tubes. Keep in mind that some of the circuits on these sites may exist in the authors mind only. Some of them do not work, I have found this out by trying. If you want to design some new vacuum tube science, please share it with us, and be prepared to fry a few parts. Experiment on cheap stuff at first, and understand the safety precautions involved with high voltages.
www.tubecad.com Some circuits are just concepts, some do not work, some work excellent, the software works good, but is limited to single stages. The Akido circuitry is an example of new thinking applied to old vacuum tubes. I have not heard anyone say bad things about this design. I bought his boards, and built them. They do work well.
www.pmillett.com Many old books, some new tech, plenty interesting reading.
http://members.aol.com/sbench101/ No new information in a few years, but several circuits that no one else would try. Yes, new vacuum tube topologies. Some of them actually work!
www.tubelab.com My site. A few circuits, designs, and concepts. The ones that are labled "circuit concepts and ideas" have not been tested, and the stuff that isn't quite ready for prime time is labeled as such. New material is being added slowly. I have a full time engineering job.
Very interesting thread, I have learned a few new things here already.
TUBELAB I visited your site and I must say I am impressed. I would like to build a SE amp later this year or early next year.
I would like to build an amp based on TS 5881 or 6V6GT power tubes. The main reason is that I have a boatload of both of those tubes. The other option might be TS 7027A or Phillips 7581A power tubes.
I have been building Tube Guitar Amps for about 9 or 10 years but have never attempted anything Hi FI before. This should be a good learining expierence for me.
I will contact you when I am ready to build.
TUBELAB I visited your site and I must say I am impressed. I would like to build a SE amp later this year or early next year.
I would like to build an amp based on TS 5881 or 6V6GT power tubes. The main reason is that I have a boatload of both of those tubes. The other option might be TS 7027A or Phillips 7581A power tubes.
I have been building Tube Guitar Amps for about 9 or 10 years but have never attempted anything Hi FI before. This should be a good learining expierence for me.
I will contact you when I am ready to build.
Stefanoo said:
I'm not saying that it's not possible, but you have to remember that this particular technology is about 80 years old now. Just about every possible connection (common cathode, common grid, common plate connections, using the control grid as the output and the plate as input, the various triode connections, and stacked topologies (cascode, SRPP, Mu stage) has been done a long time ago. There are lots of ideosyncratic designs for specific purposes the "phasetron" and CRT FM modulators, tubes for generating SSB, frequency conversion, FM demodualtion, and even analog to digital conversion have all been done already. If there are any unknown tricks that haven't been tried before, I sure haven't heard of any.
Yes. However, most of the solid state audio amps are also using the same circuits, just modified for silicon. Having PNP as well as NPN devices simplifies the ciruits a bit (no phase inverters required) and the high current/low voltage nature of SS makes it a helluvalot easier to implement OTL topologies, but the basic circuits aren't all that much different.
Often, there aren't any, and the information in something like the Radiotron Designers Handbook is just as valid today as it was when it was hot off the presses. In many cases, it's probably better since it wasn't written after so much misinformation started appearing.
Don't necessarily believe everything you read. By the 1950s, the "numbers game" was well underway. Here, you see recommendations for the use of extreme gNFB. Using huge amounts of gNFB does make the distortion figures look good to please marketing departments, but not ears. Unless the basic design is badly flawed, there is no way that you'd ever need 20+db(v) of gNFB. Also, always remember that the designs for "Big Box" systems were driven by the bottom line, not sonic excellence.
The A Number One improvement hasn't come from doing anything radically new, but due to having at our disposal improved technologies. New line and interstage xfmrs using exotic core materials that didn't exist in the 1930s allow for much better performance from 1930s circuits than were ever possible in the 1930s. There have also been vast improvements in passive components. No longer do you have to deal with leaky (in the electrical sense) foil and wax paper capacitors. Modern capacitors using the latest dielectrics simply are more reliable, and create much less distortion. Metal film resistors are quieter than the old carbon comps, and more stable as well. With solid state, you can build much better CCSs and voltage regulators. SS makes it very easy to use DC heater power for quieter operation and fewer IMD products since filament hum is no longer a problem. SS power supplies offer better regulation, even if active regulators aren't used. Power MOSFETs make for much better drivers for operating Class A2 or AB2, and makes such operation more feasible than it would be otherwise.
Novelty for the sake of novelty seldom makes for any real improvement, and often has the opposite effect.
Sorry...just a question:
the tubecad's website is basically a collection of articles.
Is it also a periodic?
What i see on the website is all i can find as tubecad journal....or it's possible to buy it somehow!?
is there any periodic journal on valves, an interesting one, that i could buy?
(like audioexpress....ect...)
thanks
Stefano
the tubecad's website is basically a collection of articles.
Is it also a periodic?
What i see on the website is all i can find as tubecad journal....or it's possible to buy it somehow!?
is there any periodic journal on valves, an interesting one, that i could buy?
(like audioexpress....ect...)
thanks
Stefano
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