Exactly. Some solid state amps sound "toobey", i.e. do not reveal own presence.
And what is the origin of this THD ?
For what I know, HD is the product of the fundamental (harmonic).
So a device,given a pure tone, adds multiples of it at lower amplitude.
This is the nature of periodic signals.
So, taking as an example a freestanding monitor two-way, the woofer is under exam: the double spring with damping that is the membrane.
The membrane isn't particularly good as a sound barrier and lower frequencies
produce nasty things, and when enclosured the air spring can contribute to produce extra (not wanted) movement that makes extra sound.
To put also into the picture is the electrical side ( talking about the woofer but it's the same for any kind of transducer ) where the coil shows an argument that is capacitative before Fs and inductive after .
For what I know, HD is the product of the fundamental (harmonic).
So a device,given a pure tone, adds multiples of it at lower amplitude.
This is the nature of periodic signals.
So, taking as an example a freestanding monitor two-way, the woofer is under exam: the double spring with damping that is the membrane.
The membrane isn't particularly good as a sound barrier and lower frequencies
produce nasty things, and when enclosured the air spring can contribute to produce extra (not wanted) movement that makes extra sound.
To put also into the picture is the electrical side ( talking about the woofer but it's the same for any kind of transducer ) where the coil shows an argument that is capacitative before Fs and inductive after .
Thanks for the input guys.
I can see already that things are starting to get more complicated than naive old me thought they would be.
Elsewhere on the forum I was reading a loudspeaker thread where a contributor had said something along the lines of "don't try inventing anything new, this is old science and has been worked through many times"... and yet there are folk disagreeing about how things work, and arguing over the best way to do xyz...
I was hoping that tube amps might be a better starting place, and that design types would already be settled as to what type has what advantages, and how each differs in sound, but it appears (after reading a SE vs PP thread) that there are plenty of things left to be debated!
Is this down to misunderstanding/misinformation (a little knowledge is a dangerous thing, etc...)? In that case, where is the best place to go to get the 'correct' explanations?
I suppose ideally it would be helpful to have soundbytes too - so you could hear what a specific distortion actually sounds like (without having to build a circuit for yourself to find out) - but I guess that would be asking too much!
I can see already that things are starting to get more complicated than naive old me thought they would be.
Elsewhere on the forum I was reading a loudspeaker thread where a contributor had said something along the lines of "don't try inventing anything new, this is old science and has been worked through many times"... and yet there are folk disagreeing about how things work, and arguing over the best way to do xyz...
I was hoping that tube amps might be a better starting place, and that design types would already be settled as to what type has what advantages, and how each differs in sound, but it appears (after reading a SE vs PP thread) that there are plenty of things left to be debated!
Is this down to misunderstanding/misinformation (a little knowledge is a dangerous thing, etc...)? In that case, where is the best place to go to get the 'correct' explanations?
I suppose ideally it would be helpful to have soundbytes too - so you could hear what a specific distortion actually sounds like (without having to build a circuit for yourself to find out) - but I guess that would be asking too much!
Comparing the sound of two completed amplifiers wouldn't help me understand the pros and cons of the many design decisions that went into building that amp.
I was meaning more at a component level; things like the difference between grid bias and cathode bias; PP with and without UL; what happens at various levels of feedback, etc.
I would like to be able to understand what is going on electrically, and to know what the end effect would be musically.
I was meaning more at a component level; things like the difference between grid bias and cathode bias; PP with and without UL; what happens at various levels of feedback, etc.
I would like to be able to understand what is going on electrically, and to know what the end effect would be musically.
You will not know until you connect it to speakers. This is like a house and house components. The components going into the house have nothing to do with the final result, sq ft and if it is a pleasurable space to live in.
If there is one 'generalization' I can say as advice is to keep away from designs with 100s' of watts or under 2 watts. Keep away from no feedback designs and lot of feedback designs (20 db +) because the likelihood of bad sound is higher. The Williamson amplifier had -20db and is likely the best type of amplifier ever made.
Let me quote the review which describes well the el34 (in UL 20db feedback): colorful, well textured, and slightly warm and lush, timbrally
Read more at Page not found | Stereophile.com
If you remove the UL and instead use it in triode, expect the harmonics to climb by two orders of magnitude.
Same thing for grid bias and cathode bias, grid bias has more chances to be a poor design, but you will gain in sound clarity&power, many designers use both at the same time.
If there is one 'generalization' I can say as advice is to keep away from designs with 100s' of watts or under 2 watts. Keep away from no feedback designs and lot of feedback designs (20 db +) because the likelihood of bad sound is higher. The Williamson amplifier had -20db and is likely the best type of amplifier ever made.
Let me quote the review which describes well the el34 (in UL 20db feedback): colorful, well textured, and slightly warm and lush, timbrally
Read more at Page not found | Stereophile.com
If you remove the UL and instead use it in triode, expect the harmonics to climb by two orders of magnitude.
Same thing for grid bias and cathode bias, grid bias has more chances to be a poor design, but you will gain in sound clarity&power, many designers use both at the same time.
No feedback amplifiers may sound very good, especially those with directly heated output triodes like 2A3 or 300B.
Good sound of Williamson amplifier (and other designs) critically depends on the quality of output transformer, which must be very high. Williamson's is definitely NOT the best design, although it has been aggressively promoted as such. Publications like Stereophile or The Absolute Sound are advertising vehicles rather than source of reliable information.
Straight pentode connection, if done right, has more power and less distortion than UL or triode connection.
Fixed bias, if done right, provides for more power and less distortion than cathode bias.
A typical SE amplifier is best with simple acoustic music, but gets congested with more complex and dynamic music, e.g. symphony or big band. PP amplifiers are not inherently sterile or uninvolving. Best PP amps rival SE in musicality; they can do what SE can do, and more.
Unfortunately for a newbie, there is no shortcut to to a better tube design. Painstakingly collecting bits of information here and there, not trusting established dogmas, and experimenting is a long but exciting journey that may take a lifetime.
Good sound of Williamson amplifier (and other designs) critically depends on the quality of output transformer, which must be very high. Williamson's is definitely NOT the best design, although it has been aggressively promoted as such. Publications like Stereophile or The Absolute Sound are advertising vehicles rather than source of reliable information.
Straight pentode connection, if done right, has more power and less distortion than UL or triode connection.
Fixed bias, if done right, provides for more power and less distortion than cathode bias.
A typical SE amplifier is best with simple acoustic music, but gets congested with more complex and dynamic music, e.g. symphony or big band. PP amplifiers are not inherently sterile or uninvolving. Best PP amps rival SE in musicality; they can do what SE can do, and more.
Unfortunately for a newbie, there is no shortcut to to a better tube design. Painstakingly collecting bits of information here and there, not trusting established dogmas, and experimenting is a long but exciting journey that may take a lifetime.
I think I'm starting to get the message; the system works as a whole, and the effects of any design decisions will vary based on the speaker load.
I was wondering if that was an option.
This is where I still get confused; the aim appears to be one of minimising distortion, yet is it not distortion that gives a tube system its characteristic sound?
This is one of the things that annoys me with mankind as it is at the moment - surely we have enough know-how and technology to bring everything into one place, so we can sort the wheat from the chaff and arrive at some best practices. It doesn't just apply to the audio world of course - the hours I've lost programming where in order to do 'a' you need to learn 'b', and to do 'b' you need to learn 'c', even though you have no interest in how 'b' or 'c' works, and 'b' and 'c' were never written with ease-of-use in mind.
OK, I'll get off the soapbox now...
DESPITE of measurable distortions they are less audible than other distortions. It does not mean that they are good and desired. Tube sound means minimum, or even absence of nasty sounding distortions. Some distortions our hearing ignores, filters out, recognizing well sounds behind them. Other distortions sound nasty, even when they are pretty low according to measurement. That's why THD when comparing different topologies reveal nothing.
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A big problem with SE amps is low power O/P.
FWIW, I'm not a fan of "simple" SE 300B setups. IMO, excessive 2nd order HD is present. OTOH, a SE 2A3 is linear, but only 3 or so W. are available.
The remark about avoiding high NFB amps is an oversimplification. The H/K Cit. 2 has something like 36 dB. of NFB in 3 nested loops and it is among the very best amps ever made. Not only honest as a Summer day is long, the "Deuce" is (sic) unconditionally stable. Unfortunately, the superior O/P "iron" Stu Hegeman designed around is not available.
Perhaps building along the lines of the H/K Cit. 5 makes sense for the OP. The superior implementation of Mullard style circuitry will do well with decent, if unspectacular, O/P trafos and power O/P is large enough to make many a commercial speaker feasible. The 12BY7 shown is getting scarce, but the 6922 cascode I've provided is a reasonable replacement. Decent 6L6GC class tubes are available for "finals".
FWIW, I'm not a fan of "simple" SE 300B setups. IMO, excessive 2nd order HD is present. OTOH, a SE 2A3 is linear, but only 3 or so W. are available.
The remark about avoiding high NFB amps is an oversimplification. The H/K Cit. 2 has something like 36 dB. of NFB in 3 nested loops and it is among the very best amps ever made. Not only honest as a Summer day is long, the "Deuce" is (sic) unconditionally stable. Unfortunately, the superior O/P "iron" Stu Hegeman designed around is not available.
Perhaps building along the lines of the H/K Cit. 5 makes sense for the OP. The superior implementation of Mullard style circuitry will do well with decent, if unspectacular, O/P trafos and power O/P is large enough to make many a commercial speaker feasible. The 12BY7 shown is getting scarce, but the 6922 cascode I've provided is a reasonable replacement. Decent 6L6GC class tubes are available for "finals".
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