There are two main reasons people recap electronics. One, regarding electrolytics(specifically), is that they dry out over time(increasing their internal resistance or ESR) or can leak their electrolyte. The other is presentation and that some caps(ie: film/foil) can sound so much more transparent than aluminum and paper. Some prefer the presentation of film and oil caps(different strokes/tastes). Individual components all generate a certain amount of thermal(Johnson–Nyquist) noise and some resistors are noisier than others. Carbon composition resistors are usually considered the noisiest, metal-films pretty quiet and wire-wounds the quietest. One can also tweak the sound of their gear with resistor swaps in certain circuits. ie: Carbon resistors will impart are warmer presentation than metal films, in most circuits. One of the reasons older tube gear has a tendency to maintain a, "warm and tubey" sound(regardless of tubes rolled and chosen) is the proliferation of carbon comp resistors, in those units. I've brought numerous pieces up to today's cleaner/more accurate presentation, with the judicious application of Vishay's metal-film resistors(for instance). Then there were the popular Sprague Black Beauty caps............
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Hi Parabolic, Aging and quality are the two reasons why you may recap. Electrolitics have a life span measured in decades, while for filmcaps it's in hundreds of years. Almost all electronics have electrolytics in the power supply. I'd leave them alone for another decade or two unless there is a problem. Often these caps leak, or bulge or show signs of burning so problem caps are easier to spot. As for any film caps, the last 20 years have seen some great improvements, so preamps made before the 21st century may benefit immensely from replacing coupling caps, but again,this tends to be in the tube preamps much more than solid state. Many high-end solid state pre-s use no coupling caps, so your benefit, if any, is less clear. Best, Erik |
You might want to check out this video. There's even a parts list at the end. https://www.youtube.com/watch?v=G9vtk4CONiU I'm not sure when the Panasonic FC and FM caps were introduced, but they are very nice upgrades. It seems all the caps replaced are power supply related, so they should be relatively inexpensive. |
rodman99999 brings up some of the key reasons to re-cap older audio gear. the thing to understand is that re-capping is directed mostly to electrolytic caps which are mostly in the power supply. Boutique electrolytic caps (paper in oil, silver/gold foil in oil, etc) are also in the signal path but they encounter much smaller signal amplitudes hence their degradation over time is much less. So another reason to re-cap is that over time electrolytic capacitors in the power supply are heat cycled & heat is one of the worse enemies of caps. As rodman99999 wrote these caps’ ESR increases & the power supply becomes grungier. Additionally, power supply caps (due to heat cycling) can show bulging on the top. This is a sign of internal mechanical failure & the capacitor can explode while operating thereby destroying a lot of other things inside the amp. You don’t want this to happen - repairs can be very expensive. So, if the audio gear is 10-15-20 yrs old, re-cap the power supply electrolytics.... Do not re-sist! ;-) |
I should also say, going back to your original question, unless the resistors are thermally stressed, they will probably last thousands of years. :) They are incredibly stable over time, while electrolytics go bad just sitting on a shelf. That's another reason why re-resisting is not something you should consider in that unit, especially if you like the sound of it. :) Best, Erik |
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