Throw in a few bottles of red wine and there’s your typical subjective listening panel.
I think Bob Cordell made a profound comment in a Burning Amp presentation at about 44:50 in the video linked below. Paraphrasing as I recall it, he said two good amps [i.e. re THD] can sound different because they are misbehaving differently. He was emphasizing the importance of thorough testing into challenging loads and near clipping. Clearly, he's a believer in the benefits of large loop gain and low distortion. And he acknowledges that good THD-performing amps can sound different if they have subtle flaws. Very worth watching, IMHO.
https://www.diyaudio.com/community/...-1-audio-power-amp.387115/page-3#post-7338180
https://www.diyaudio.com/community/...-1-audio-power-amp.387115/page-3#post-7338180
So, back to the proposition that a correctly sized electrolytic introduces no additional distortion as evinced by AP tests.
LMAO!
Bonsai, you left out the more cultured listening panel. Three fingers of good Scotch before they start!
Hello Hierfi,
Look, I'm really sorry. You're entering a battle with zero ammunition here. You're just cresting the hill yelling "Bang! Bang!" and wondering why no one is falling over. Well, we are ... with laughter.
Okay. Now the thread OP was asking about distortion from capacitors. You are so far off topic for starters.
I'm going to politely suggest, as a moderator, that you either stick to the topic with valid arguments that pertain to the subject matter, or begin your own little world in your own thread for the topics you are pursuing. Be aware though, stating ideas that are not factual will probably result in posts you won't like too much. Reality is a B*tch sometimes. You can have your say as free speech in a thread for that topic. Be aware that others also have freedom of speech and you may well find yourself dealing with points of view that are not in agreement with yours - on topic in that thread.
So have a defensible position that doesn't rely on "could be" or "we don't know everything" and have at it. You are dealing with people who have experience in the field, electronics and the laws of physics. We also know how to set up experiments to yield valid data.
Now just to quell the next issue that is bound to come up. I post as a normal member without special powers unless I am called to deal with an issue. Then I have work to do. Moderators are normal members with extra work, that's all. Our actions are peer reviewed, if we participate in a thread, we request a different moderator to look in, that's all. So we are not high and mighty.
Bonsai, you left out the more cultured listening panel. Three fingers of good Scotch before they start!
Hello Hierfi,
Look, I'm really sorry. You're entering a battle with zero ammunition here. You're just cresting the hill yelling "Bang! Bang!" and wondering why no one is falling over. Well, we are ... with laughter.
Okay. Now the thread OP was asking about distortion from capacitors. You are so far off topic for starters.
I'm going to politely suggest, as a moderator, that you either stick to the topic with valid arguments that pertain to the subject matter, or begin your own little world in your own thread for the topics you are pursuing. Be aware though, stating ideas that are not factual will probably result in posts you won't like too much. Reality is a B*tch sometimes. You can have your say as free speech in a thread for that topic. Be aware that others also have freedom of speech and you may well find yourself dealing with points of view that are not in agreement with yours - on topic in that thread.
So have a defensible position that doesn't rely on "could be" or "we don't know everything" and have at it. You are dealing with people who have experience in the field, electronics and the laws of physics. We also know how to set up experiments to yield valid data.
Now just to quell the next issue that is bound to come up. I post as a normal member without special powers unless I am called to deal with an issue. Then I have work to do. Moderators are normal members with extra work, that's all. Our actions are peer reviewed, if we participate in a thread, we request a different moderator to look in, that's all. So we are not high and mighty.
Last edited:
Hi BSST,
This is exactly correct. We perform the same testing at higher power levels to characterize these faults. This has been known for a very long time.
What shows up are board layout issues, wiring issues and ground path issues. That and current limiting (very basic). If you read the SymAsym development threads, this was an issue and simply changing the PCB layout dropped distortion. Doug Self and Bob Cordell have both addressed these issues in their books, and others I am sure./ But the design has to perform well at low levels before you can even begin to explore higher power behaviour, higher power levels will exacerbate the existing low power issues and maybe make them easier to find.
Most listening is done at an average of a few watts, and that can be pretty loud. So, 1 watt tests are more than valid.
Now, please, back to the original topic of the thread.
This is exactly correct. We perform the same testing at higher power levels to characterize these faults. This has been known for a very long time.
What shows up are board layout issues, wiring issues and ground path issues. That and current limiting (very basic). If you read the SymAsym development threads, this was an issue and simply changing the PCB layout dropped distortion. Doug Self and Bob Cordell have both addressed these issues in their books, and others I am sure./ But the design has to perform well at low levels before you can even begin to explore higher power behaviour, higher power levels will exacerbate the existing low power issues and maybe make them easier to find.
Most listening is done at an average of a few watts, and that can be pretty loud. So, 1 watt tests are more than valid.
Now, please, back to the original topic of the thread.
Can you point to substance warranting of such remarks as you found particularly offence?Hello Hierfi,
Look, I'm really sorry. You're entering a battle with zero ammunition here. You're just cresting the hill yelling "Bang! Bang!" and wondering why no one is falling over. Well, we are ... with laughter.
Okay. Now the thread OP was asking about distortion from capacitors. You are so far off topic for starters.
I'm going to politely suggest, as a moderator, that you either stick to the topic with valid arguments that pertain to the subject matter, or begin your own little world in your own thread for the topics you are pursuing. Be aware though, stating ideas that are not factual will probably result in posts you won't like too much. Reality is a B*tch sometimes. You can have your say as free speech in a thread for that topic. Be aware that others also have freedom of speech and you may well find yourself dealing with points of view that are not in agreement with yours - on topic in that thread.
So have a defensible position that doesn't rely on "could be" or "we don't know everything" and have at it. You are dealing with people who have experience in the field, electronics and the laws of physics. We also know how to set up experiments to yield valid data.
Now just to quell the next issue that is bound to come up. I post as a normal member without special powers unless I am called to deal with an issue. Then I have work to do. Moderators are normal members with extra work, that's all. Our actions are peer reviewed, if we participate in a thread, we request a different moderator to look in, that's all. So we are not high and mighty.
I'm not going to get dragged into an off topic discussion.
I wasn't offended, you're just off topic.
I wasn't offended, you're just off topic.
Okay, now I am going to give you an official warning.
Drop it, stop.
You are off topic and continuing may bring sanctions.
You can PM me if you have questions, but this is over in the thread.
I was vaguely thinking something like this earlier in the thread, so I'll throw it out now:
For measuring capacitor distortion, someone way back in the thread mentioned a series resistor equal to the capacitive reactance at a certain test frequency (ISTR this goes back to the Jung-Marsh Picking Capacitors article), and measuring the resultant distortion across the resistor (or across the capacitor, they should be pretty much the same). It seems to me this could be done throughout the range of hearing (or other desired range), changing the resistor value to match reactance, and of course higher frequencies may require sub-ohm resistances.
It's a good argument that a capacitor should be chosen with the circuit impedance in mind so that the voltage across the capacitive reactance is as low as practical. On the other hand, following the above procedure should give a "full characteristic" and allow one to calculate the capacitor's distortion contribution in any circuit.
For measuring capacitor distortion, someone way back in the thread mentioned a series resistor equal to the capacitive reactance at a certain test frequency (ISTR this goes back to the Jung-Marsh Picking Capacitors article), and measuring the resultant distortion across the resistor (or across the capacitor, they should be pretty much the same). It seems to me this could be done throughout the range of hearing (or other desired range), changing the resistor value to match reactance, and of course higher frequencies may require sub-ohm resistances.
It's a good argument that a capacitor should be chosen with the circuit impedance in mind so that the voltage across the capacitive reactance is as low as practical. On the other hand, following the above procedure should give a "full characteristic" and allow one to calculate the capacitor's distortion contribution in any circuit.
Last edited:
Hi benb,
Yes. Also the dielectric makes a difference, so capacitor type and value.
There are times a circuit will force the use of a capacitor and type. You then have to live with the results. All you can do is minimize the effects. It may also be that the type of circuit generates high distortion all on it's own, and it can be sensitive to capacitor characteristics. But from what I have seen, capacitor manufacturer doesn't affect the result as much as capacitor type, dielectric and construction. For example, they do make capacitors for switching power supplies that have better high frequency characteristics. No free lunch here as other characteristics may be affected. But using types for HF switching perform similarly among good brands. Same as normal types.
One thing that does matter, again similar among good brands, the higher the voltage rating is up to a point, the better characteristics the capacitor has. I do have to stress the fact that the capacitor must fit the physical space or you generate other issues.
Yes. Also the dielectric makes a difference, so capacitor type and value.
There are times a circuit will force the use of a capacitor and type. You then have to live with the results. All you can do is minimize the effects. It may also be that the type of circuit generates high distortion all on it's own, and it can be sensitive to capacitor characteristics. But from what I have seen, capacitor manufacturer doesn't affect the result as much as capacitor type, dielectric and construction. For example, they do make capacitors for switching power supplies that have better high frequency characteristics. No free lunch here as other characteristics may be affected. But using types for HF switching perform similarly among good brands. Same as normal types.
One thing that does matter, again similar among good brands, the higher the voltage rating is up to a point, the better characteristics the capacitor has. I do have to stress the fact that the capacitor must fit the physical space or you generate other issues.
Hi anatech,
I'm in total agreement with all your comments. We could be choir members if I could carry a tune... And on topic, I believe capacitor distortion is a non-issue with a properly chosen and properly applied capacitor.
Best regards,
Hi BSST,
I'm afraid I am a terrible singer!
Yes, but this stuff is well known to most signal engineers (not just audio). I think if you read posts from most good techs and engineers here, you'll see they say similar things.
I'm afraid I am a terrible singer!
Yes, but this stuff is well known to most signal engineers (not just audio). I think if you read posts from most good techs and engineers here, you'll see they say similar things.
I'm sure that's true. I just appreciated Cordell saying it succinctly, especially since there seem to be so many naysayers here and in audio press. I'm an enthusiastic proponent of large loop gain and vanishingly small THD, even if artifacts are well below hearing perception. Pursuit of low THD is beautiful in its own right, and negative feedback ranks near the invention of the transistor in importance, IMHO.
Best,
Best,
But why bother with this if you know the cause of the problem is in undersized ie low value capacitors? The solution is to keep the -3dB low end well below the lower cut off frequency and numerous measurements have confirmed this - the most famous being Self’s AP plot.
As to the DA ‘smearing’ thing, a few LTspice plots will quickly show that the DA capacitor coupling through it’s associated resistor introduce nano-amps across the actual dielectric which itself represents a very low impedance (< 1ohm in most cases, while the signal currents are orders of magnitude higher. But, the DA component is shifted down in frequency so it’s at best 1-2 Hz and even lower in most cases.