Originally Posted by Frank_Case
One man's ruined audio is another man's bliss. What you are asking is subjective. But here's a few things to consider...
(1) New caps tend to brighten the sound.
(2) New caps tend to uncover underlying anomalies in the circuit if they exist, because new caps are more accurate then old caps. One recap job I did using excellent caps unexpectedly sounded less then perfect because the underlying transistors in the circuit sounded grainy, and the recap accentuated this deficiency. Most high end equipment will not suffer this way from a recap, but you should be aware of the potential.
(3) New electrolytic caps tend to have less leakage meaning they can reduce noise and biasing problems that have crept into the circuit. A leaky cap is one that is turning into a resistor. And resistors are a primary source for noise in circuits. Also, unwanted leakage can introduce small voltages at points in the circuit that conflict with normalcy.
(4) Electrolytic caps have greatly improved in sound quality over the past 20 years due to improvement in ESRs. The best modern electrolytics will sound similar with some minor differences.
(5) Reliability is more important than minor sound differences between quality caps. To ensure reliability, use a temp rated cap of at least 105C. Also, pay attention to the Mean Time Between Failure (MTBF) metric published by the manufacturer. The best have MTBFs in the range of 5000 hours (example Panasonic FR series). At minimum, IMHO use a cap rated at 2000 MTBF.
(6) My favorite inexpensive low-ESR long-life caps are the Panasonic FC/FM/FR series with the later FR series being the most reliable. They have a crisp clear slightly hard-edged sound that is very pleasing. Black Gate electrolytic caps also sound very good, being slightly softer sounding then the Panasonic caps.
(7) The transient and high frequency response of electrolytic caps can sometimes be improved by adding small polypropylene bypass caps across each electrolytic. You may like the effect. You may not. In some rare cases I have found bypassing to increase sibilance.
As someone already suggested, recap a channel or two and see if you dig it. Same with bypassing.
Yes and no. It really depends on the type of capacitor being chosen. Some types are very unsuitable for audio applications. I've see these in everything from guitar amplifiers to pro audio gear being manufactured today. Another issue has to do with the resistors being used along with them...
All of the electronics in a circuit work together as a whole.
Sometimes new tubes make an audio device bright and capacitors get the blame...
The tube pro audio gear I manufacture gets nothing but NOS capacitors for coupling. There are a few brands that are exceptional and very easy to find online. One being EVOX. I use these and Panasonic for solid state.
For tubes (PCB), there's RIFA, Wima, Siemens, and others.