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Is this 007-039489 kit do I need to recap my 1966 Black Face Fender Pro Reverb, model AA165 with the Premium Sprague Atoms? This kit seems the closest match to original but there is one difference: The original caps are 2-70mfd 350v. Any big deal going to the 2-80mfd 400v?
Asked by Anonymous on January 17th, 2016.
There should be no problem going higher on the values but you never want to go lower. In this case you should be good to go.
NO! NOT AT ALL There is an old adage with the old TV and radio repairmen. More capacitance or a higher voltage rating are always okay. Don't put a 220uF or 470uF or a 1000uF cap in place of a 70uF, but 80uF or 100uF or even 150uF are just fine. The tolerances on the old filter caps were usually +50% or even +100% and -5% to -20%, so less capacitance is bad, and the designers were not concerned with having more, only less. If the old one was rated for 450 volts, a 600 volt rating will also be just fine. If you read the tolerance of most filter caps, they will say -20% / +50% so a 70 uF cap could be anywhere between 56 uf and 105 uF and it is still within factory specs. We try to keep the -% lower than the +%. For this filter cap application, we are merely shunting the 60 and or 120 Hz and any harmonics thereof to ground, and out of the DC plate supplies for the amp. So the cap filters the DC out, and allows all the AC ripple to pass through to ground, where it is shorted back to ground. If we were trying to offset the AC to make a motor run smoother, then the tolerance would be closer to 4%, because the cap has become a precision timing device. That's a whole different ballgame, and one best left for fixing your air conditioner. For simple filtering the more capacitance, higher voltage has always been an accepted rule of thumb, within reason. Too much capacitance and the rectifier tube can suffer a shorter lifespan, but you can go pretty high and still get away with it!! Some old P style caps had a tolerance of +100%/-20%. This means your 70 uF could be 140 uF and still be in spec. They designers were much more concerned about the capacitance being too low, rather than too high. Any difference you will hear between 70 and 80uF is because the old caps were worn out. There is nothing to worry about!
Is this for a bandmaster?
Asked by Anonymous on June 29th, 2017.
This is a cap set for the blackface Super Reverb.
What’s the “premium” actually mean?
Asked by Anonymous on January 24th, 2018.
The premium caps set comes will all Sprague Atom caps.