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RE: NYAL OTL 3

Posted by Lew on November 20, 2010 at 07:50:27:
Actually, film caps can last for quite a long time, not to say "forever", so your WIMAs are probably OK functionally. However, to my ears they are NOT a good sounding coupling cap, and this is a critical application. (Here I use the term "coupling" to refer to a cap that couples the input or driver stage to the output stage; I do not refer to the electrolytic caps that couple the output stage to the spkr, unique to Futterman types.) So I agree with your intention to replace the WIMAs, because IMO they are awful.

Adding more output stage-to-speaker capacitance might conceivably help lowest bass response, but there is no need to get crazy about it. More benefits could be gained by bypassing the spkr coupling electrolytics with a good film cap of the highest value and quality you can afford or find. (You only need a 200V rating for whatever you choose, so that usually saves some money vs high voltage caps.) Then you can bypass THAT cap with more and even better film caps of progressively lower value. There is no rule for that but I generally shoot for a 1:100 ratio of values, e.g., a 100uF film cap can be bypassed by a 1uF film cap and then again by a .01uF film cap.

Besides replacing and upgrading the speaker coupling electrolytics, you probably also should do the same for your power supply electrolytics, which are also pretty old by now.