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Old 28th December 2010, 07:21 PM   #21
kevinkr is offline kevinkr  United States
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Everyone will agree looking through an open window gives a better view then through glass. You can debate which sort of glass is the clearest, but no glass is always better..
Good analogy, and I try to balance my design choices based on the avoidance of excessive caps in the signal path, and in particular cathode bypass caps. My current system has not one cathode bypass capacitor.
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Old 28th December 2010, 09:43 PM   #22
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As the subject of caps came up, this is Stephie Bench´s findings.

The "Sound" of Capacitors
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Old 29th December 2010, 08:31 AM   #23
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As the subject of caps came up, this is Stephie Bench´s findings.
With respect to effects of capacitors to sound quality, the value of this article is nonexistent.
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Old 29th December 2010, 12:38 PM   #24
kevinkr is offline kevinkr  United States
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With respect to effects of capacitors to sound quality, the value of this article is nonexistent.
I respectfully disagree - the issue he discusses has a significant bearing on how capacitors sound. The fact that he objectively demonstrates measurable non-linearity in capacitors of various dielectrics indicates that these capacitors are all adding significant distortion, and hence coloration to the signal. The only part that isn't really relevant to current hifi usage is the section on ceramic coupling caps and that is still useful to the guitar amp guys, and is a good demonstration of why you should avoid them in the signal path of hifi amps.
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Old 29th December 2010, 01:35 PM   #25
M Gregg is offline M Gregg  United Kingdom
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KevinKr,

I agree with your comments,

As stated in the thread, DC coupling does "sound better" than any capacitor. The less components in the signal path the better. As long as low frequency saturation is not a problem.

Interesting that the cost does not always mean "better" from a component point of view. Non inductive comes to mind. Dielectric type and conductor material.

Its easy to use metals like silver for wire tests, just go to the local jewelry suppliers and buy silver wire sleeve with PTFE any impurities tend to be copper. use the correct solder. Only problem is it seems to show any other weaknesses in the system! Good fun though.

Just for interest I tried replacing caps in the tone control on an Epiphone Les Paul to disk ceramic because they are used in the Gibson. Guess what it made it sound very similar.
Where do you get your: Quote :The Russian FT-3 is good and not too expensive a place to start. I use TFTs and Vcaps mostly

Regards
M. Gregg
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Old 29th December 2010, 02:30 PM   #26
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The fact that he objectively demonstrates measurable non-linearity in capacitors of various dielectrics indicates that these capacitors are all adding significant distortion, and hence coloration to the signal.
The author demonstrated some non linearity in D-E curve. The photos taken from oscilloscope screen do not have any scale. What can be analysed base on those remains unclear.
Also I can not find from the article any straight and clear connection between audible distortion in an amplifier and the described unlinearity at D-E curves. Completely different case is if one believes that these has someting in common.
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Old 29th December 2010, 04:31 PM   #27
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Originally Posted by artosalo View Post
The author demonstrated some non linearity in D-E curve. The photos taken from oscilloscope screen do not have any scale. What can be analysed base on those remains unclear.
SB called out the voltage swings in the text- something like 70V across the caps, if memory serves, stating that this much voltage was needed to be able to readily measure the effects. Now, that's not exactly typical usage with respect to coupling caps, where the voltage across the caps in the passband is very, very small.
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Old 29th December 2010, 04:45 PM   #28
kevinkr is offline kevinkr  United States
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SB called out the voltage swings in the text- something like 70V across the caps, if memory serves, stating that this much voltage was needed to be able to readily measure the effects. Now, that's not exactly typical usage with respect to coupling caps, where the voltage across the caps in the passband is very, very small.
No, not typical in the passband, however at the LF corner the AC voltage across the dielectric is increasing as is the resulting distortion. This could be a significant issue in stages driving low mu power triodes in the presence of significant levels of subsonic energy. (LP playback for instance, and certain types of electronic music) I actually don't know how voltage dependent these effects are wrt to performance of the dielectric - however as a point of comparison under controlled conditions the experiment is valid if not completely documented. This is very relevant to passive cross-over design where the AC voltages across capacitors can be large.

I still think any electrolytic in the signal path is a more significant issue if a reasonably good coupling capacitor is being discussed.
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Old 29th December 2010, 05:45 PM   #29
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But at 24mA as in SB's tests? Even with a grid resistance as low as 10k and a swing as high as 100V, the signal current is a small fraction of that.
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Old 29th December 2010, 06:27 PM   #30
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Some of us here think that all capacitors at the signal path are harmful with respect to sound quality of an amplifier.

Should we then concentrate to construct dc-coupled tube amplifiers only ?
Would such amplifers sound better ?

How many capacitors have the music we play already passed thru before it reach our tube amplifier and its last two to three capacitors - those that are claimed to create distortion to the sound ?

What about these earlier "some 50 pcs." during the chain from the instruments via the studio etc. etc. and finally out from our CD player ? Don't these have the same effect ?

If they had, why should we then concentrate to get rid of these last few capacitors ?

I fully agree that zero-biased tantalum or electrolytics are not the best capacitors in the signal path.
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