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Re: Bypass caps, a little more information

"If you are really interested in reducing time smear, according to the way this article models capacitors, you are going to be much better off using parallel capacitors instead. That is, if you need a coupling cap of 4uF, use 4 x 1uF capacitors or 2 x 2uF. This should reduce the memory effects substantially."

This is exactly the construction that has been touted by Dick Marsh for his "self-bypassing" Multi-Cap line. Multiple elements paralleled to build a larger value cap in one package seems to fit right in with the points made in the article. It would also seem to be quite advantageous to have those (4) 1 uf caps you mention be as precisely matched as possible. Obviously if you had four caps of different uf values and were to discharge or charge them at the same rate, then at any given time the state of charge of each cap will be different. So unless the four caps you describe (or the Multi-Cap) have tight matches, could the accumulation of the smaller errors by multiple capacative elements be more harmful than one error from a single element??

Bob Pease's writings correspond closely to the famous Jung/Marsh "Picking Capacitors" article from Audio in 1980. Prior to that article being published, the "hot" caps for audio were tantalum electrolytics!

The one danger in this is negelcting to take a "wholistic" approach to it. A single cap of any type/configuration has to be evaluated as part of the circuit/device as a whole. There are other factors to be considered. For example, does the presence of a high DC voltage across the cap change the results? In their article Jung/Marsh reported that the application of a "polarizing" voltage improved the performance of some caps. It would be interesting to see the results in Pease's figure 7 with 200-400 volts DC applied along with the AC signal. Etc., etc...

And in the case of audio gear, what is impact of the caps' D/A on tone? Many here love oil caps - which could lead you to think that either:

1. They are poor judges of tone quality (not likely in any event)
2. D/A is irrelevant (or even beneficial??) in audio frequency circuitry (I don't think so...)

Or my personal conclusion:

3. D/A performance is one of MANY variables that contribute to the tone quality of a given unit.

This post is a great thought (re) starter! Thanks for bringing this all to mind again.



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