i guess i have found what works for me, fewer parts, class A, never mind that i have to use large heatsinks......
and with todays' smps, it is now very easy....
and with todays' smps, it is now very easy....
sure, problem starts when someone claims this or that....
it would make things easier it the technical aspects were discussed, without emotions attached and no commercial interests inferred....
everything has a context, well said....i really enjoy watching your lectures at the burning amp festival, viewing it over and over till get the meat...Nelson Pass too....i missed Roger Modjeski..
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the question now is, how much of the harmonics produced by instruments, how much by the amplifier, has anybody attempted to measure? can it even be measured?
the reason imho why watching lectures by Pass and Cordell and the rest at Burning amp is more enjoyable, is because those talk about actual amps showing actual circuits, learning is more intimate that way.......
Yes, of course, thanks for bringing that up. Though, I am not sure that it is as large a factor in listener preference as plain harmonic distortion. Someone above mentioned that most (all) acoustic instruments produce copious amounts of harmonics - indeed, it is the harmonic content and distribution that allows us to recognize the different instruments in the first place.
IM distortion, as I understand it, produces non-harmonic components which are alien to actual instruments. So I think we could make a case for minimal IM in an amp that would have any hope to be well received, sound-wise*.
Jan
* I am aware that both IM and HD are caused by the same non-linearity in an amp. But the relative amplitudes etc of the two distortions may be different in different amps.
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Tony, Ok, here’s a technical question! do you have a link to a thread where you explain the “High Voltage“ ACAs? Do you cascode the JFETs?
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i discussed it at the ACA thread with Zen Mod and the others, several recommendations were made including the use of the irfp150 mosfets. The jfet input buffer was fed off an RC supply to drain to mitigate the Vdg ratings of 40vdc..2sk117 is slightly higher in Vdg specs, no cascode for the input jfet buffer...the RC supply to the input jfet was the only significant change..
my ACA aka Kampana was meant for local consumption only....and for group build outs...
about 80+ boards made by happy campers and at very low cost...
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in the German magazine "FUNKSCHAU" special edition from 1978, ("Funkschau Spezial - High Fidelity2") is to find a report concerning "TIM" from this author - go to post #44 under
https://www.diyaudio.com/forums/sol...ble-electr-audio-magazines-5.html#post6747359
I am looking for a PDF version of this issues.
https://www.diyaudio.com/forums/sol...ble-electr-audio-magazines-5.html#post6747359
I am looking for a PDF version of this issues.
Could you maybe be a bit clearer about what you mean?
If you by any chance think that the harmonic frequencies that is a part of the normal sound of an instrument is the same as the harmonic distortion produced by an amplifer you must say so.
Stein
From the point of view of the amplifier, the harmonics of an instrument just look like another bunch of fundamentals, if you get my drift.
That is why professionals often measure distortion using a multitone stimulus.
There is an AES standard 32-tone stimulus that is often used, and for instance REW has the option to use a multitone for distortion measurement, harmonic as well as IM.
The main issue is how to interpret the results. How to translate the differences from two amplifiers from a multitone measurement into audible differences.
Jan
Exactly right Jan
I asked him a question in a post 2 minutes before your post.
Here
My intention was to have him aswering that post before I did put up a post like yours.
What you are posting is ofcourse exactly right and I wonder why it's so hard for some to understand it.
Stein
i thought my post was clear...of course musical instruments have harmonics and we do not call that distortions if i understand it right...
now that is the signal fed to the microphone with its own set of colorations and thence to the the amplifier with its own set of distortions...
how do we separate/distinguish? isn't it that we use a single tone or combinations of single tones to test and never the music to test for such things as thd?
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If we were only playing one instrument through the amplifier, there might be some truth to what you are saying, in that the harmonic distortion of the amplifier would just modify the sound of the horn, etc.
But that is not the real world.
Even with some single instruments, the sound will be made to sound bad. Consider a cymbal. What is its frequency? It is more like noise than a tone. Noise has an almost infinite number of frequencies, all potentially intermodulating with each other to produce IM products at all kinds of frequencies, including frequencies lower in the audio band. That is the spit you hear on a cymbal when it is not reproduced linearly. If you think in terms of intermodulation, instead of simple harmonics, you will see a different picture.
Cheers,
Bob
But that is not the real world.
Even with some single instruments, the sound will be made to sound bad. Consider a cymbal. What is its frequency? It is more like noise than a tone. Noise has an almost infinite number of frequencies, all potentially intermodulating with each other to produce IM products at all kinds of frequencies, including frequencies lower in the audio band. That is the spit you hear on a cymbal when it is not reproduced linearly. If you think in terms of intermodulation, instead of simple harmonics, you will see a different picture.
Cheers,
Bob
that is why we do not use music for analysis,,,..we use sine waves...
but the real world has audiophiles who are all ears to the music...
but the real world has audiophiles who are all ears to the music...
Well nobody forces you to use single tones for distortion measurement. And no competent audio designer will ever say that there is a direct link between single tone THD measurements and sound quality; it's of course much more involved. Single-tone THD is a useful tool in the initial phases of a design, but it's not the end.
And multitone measurements and looking at IM measurements, as pioneered by Bob, gets much closer.
No disagreement to this from me.
@stinius - sorry to meddle in your plan ;-)
Jan
And multitone measurements and looking at IM measurements, as pioneered by Bob, gets much closer.
No disagreement to this from me.
@stinius - sorry to meddle in your plan ;-)
Jan
for me most close to the perceived sound impression is the THD character and not the value in %. If you look to this diagrams on "stereophile" measurements of various amplifier reviews (diagrams with fundamental notched out) you know what I mean. Go to the links in post #2 under
Choosing of best sounding OP AMPs for the lowest possible THD+N -really the best Way?
for any examples.
If there is to observe sine wave character (and not sawtooth- or triangle character etc.) sound impression is good in most cases, as long no weak transormator and capacitor in the power supply.
Unfortunately these diagrams are mostly not direct comparable because too many differences for the measurement conditions are still present.
If there such diagrams always for 1-10-100 Khz (100 KHz because only single tone) at different output power (e. g. o,1-1-10-100 watts) and different load impedance (2-4-8 ohms) one could at least say which amplifiers should not be shortlisted for a listening test.
If one had a compression test in addition (tone bursts at 16-8-4-2-1 ohms)
additional models would be eliminated from the preselection.
This was only perform from the German test magazine "Production Partner" in the 90s and was very informative regarding the power supply behavior.
For the manufacturers of audio stuff, however, it would have been very bad if these test procedures had been established for 30-40 years because many amplifiers had not been sold. But users would not have had to waste as much time and money as they did in reality .
P.S.: Anywhere on this URL under
Audio Amplifier Design
was explain in detail, why THD values don't increase significant, if there are small needle impulses or similar (extrem audible) distortion products present (caused by distortions e. g. due too low idle current in the output stage or not correct calculated Cdom values or more than two voltage gain stages within the NFB loop).
Unfortunately just I don't find in the moment (maybe only of the old URL - maybe one of the members know the exact URL therefore - thank you very much).
Choosing of best sounding OP AMPs for the lowest possible THD+N -really the best Way?
for any examples.
If there is to observe sine wave character (and not sawtooth- or triangle character etc.) sound impression is good in most cases, as long no weak transormator and capacitor in the power supply.
Unfortunately these diagrams are mostly not direct comparable because too many differences for the measurement conditions are still present.
If there such diagrams always for 1-10-100 Khz (100 KHz because only single tone) at different output power (e. g. o,1-1-10-100 watts) and different load impedance (2-4-8 ohms) one could at least say which amplifiers should not be shortlisted for a listening test.
If one had a compression test in addition (tone bursts at 16-8-4-2-1 ohms)
additional models would be eliminated from the preselection.
This was only perform from the German test magazine "Production Partner" in the 90s and was very informative regarding the power supply behavior.
For the manufacturers of audio stuff, however, it would have been very bad if these test procedures had been established for 30-40 years because many amplifiers had not been sold. But users would not have had to waste as much time and money as they did in reality .
P.S.: Anywhere on this URL under
Audio Amplifier Design
was explain in detail, why THD values don't increase significant, if there are small needle impulses or similar (extrem audible) distortion products present (caused by distortions e. g. due too low idle current in the output stage or not correct calculated Cdom values or more than two voltage gain stages within the NFB loop).
Unfortunately just I don't find in the moment (maybe only of the old URL - maybe one of the members know the exact URL therefore - thank you very much).
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Often people make no distinction between good or bad amps, or preferred or not preferred amps.
For me a 'good' amp is one that is transparent to the signal, taking away as little as possible, adding as little as possible.
Very often this is a very different ranking than preferred or less preferred amps.
Jan
For me a 'good' amp is one that is transparent to the signal, taking away as little as possible, adding as little as possible.
Very often this is a very different ranking than preferred or less preferred amps.
Jan
found by chance : Meeting with Matti Otala (magazine "l' Audiophile")
Who can convert the file format from attached jpg-files by OCR software to transfer the text in a translation resp. language tool (e. g. in "Google) ?
Who can convert the file format from attached jpg-files by OCR software to transfer the text in a translation resp. language tool (e. g. in "Google) ?
Attachments
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