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I've been working on a Gibson EA-35T amp to correct some problems left over from a previous repair--it had an intermittent noise that I traced to a short caused by two components whose leads were too close together, partly a result of the original rat's nest-wiring. (Were terminal strips that expensive?)
Anyway, I found that pretty quickly, so I was trying to give the client his hour's-worth of my time by seeing if there was anything else I could tweak. Honestly, the amp sounded a bit "unexciting" to me. The previous tech had replaced the original first stage bypass with the standard TVA axial caps I've seen many techs use--the ones with a black covering and green writing.
Out of curiosity, I clipped a different cap in parallel. Now, I know that there is a psychoacoustic effect; I try to minimize this by assuming that a component change is going to make no difference and that it's a waste of time. In this case, however, the difference was pretty striking. Now the amp had some liveliness and transient response. So, I tried another different brand of capacitor. Same thing. I won't go through all the variations I tried, but be assured that I tried my best to eliminate all variables. I also tried a couple of these same TVA caps from my parts drawer.
The experiment seemed to point to the conclusion that the TVA caps really aren't that great for this application. Other caps I tried were Elna RFS, Nichicon ES and KZ, etc... Everything I tried sounded subjectively better, and all these are cheaper by a wide margin than the TVAs. It's not boutique-price mojo. I'd be hard-pressed to pick among the other types I tried.
Has anyone else had similar or contrary results? Sometimes I think we don't pay enough attention to cathode bypasses even though they are very much in the signal path, especially in a single-ended circuit.
In the future, if I really need an axial electrolytic, I think I'll go with the Vishay/BC Components types. I've had better luck with those.
Anyway, I found that pretty quickly, so I was trying to give the client his hour's-worth of my time by seeing if there was anything else I could tweak. Honestly, the amp sounded a bit "unexciting" to me. The previous tech had replaced the original first stage bypass with the standard TVA axial caps I've seen many techs use--the ones with a black covering and green writing.
Out of curiosity, I clipped a different cap in parallel. Now, I know that there is a psychoacoustic effect; I try to minimize this by assuming that a component change is going to make no difference and that it's a waste of time. In this case, however, the difference was pretty striking. Now the amp had some liveliness and transient response. So, I tried another different brand of capacitor. Same thing. I won't go through all the variations I tried, but be assured that I tried my best to eliminate all variables. I also tried a couple of these same TVA caps from my parts drawer.
The experiment seemed to point to the conclusion that the TVA caps really aren't that great for this application. Other caps I tried were Elna RFS, Nichicon ES and KZ, etc... Everything I tried sounded subjectively better, and all these are cheaper by a wide margin than the TVAs. It's not boutique-price mojo. I'd be hard-pressed to pick among the other types I tried.
Has anyone else had similar or contrary results? Sometimes I think we don't pay enough attention to cathode bypasses even though they are very much in the signal path, especially in a single-ended circuit.
In the future, if I really need an axial electrolytic, I think I'll go with the Vishay/BC Components types. I've had better luck with those.
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