I have had excellents experiences , paralleling caps for power supplies filters purposes .
The power supply total impedance falls and you will have a better frequency response
and bandwidth .
Example : Instead to use a 220 uf x 450 v cap , I use 5 x 47 uf x 450 v paralleled .
You can mix values too , BUT is very advisable that you use all capacitors rated to the same voltage value , and if possible ( not an obligation ) all the same brand .
Carlos
The power supply total impedance falls and you will have a better frequency response
and bandwidth .
Example : Instead to use a 220 uf x 450 v cap , I use 5 x 47 uf x 450 v paralleled .
You can mix values too , BUT is very advisable that you use all capacitors rated to the same voltage value , and if possible ( not an obligation ) all the same brand .
Carlos
If you mean the bypass cap on the cathode bias, it's highly recommended, within reason. For example, with an EL84 I prefer a high quality 1000uF electrolytic paralleled with a good film capacitor in the 1 to 4.7 uF range. Even better would be five 220uF electros with a 10uF film, a 1 uF film and a very high quality film/foil 0.1uF cap, but this gets expensive and bulky and the improvements may not be noticeable.
Yes . No problem , you can use this method too , and more you must ( or
you can ) by-pass all the stuff , with a good quality film capacitor perhaps
0.47 uf or 1 uf x 63 v , as said above .
My only disagreement point from Fenris reply , is to use very large capacitors
on the cathode bias , due to the " blocking " occurrence .
It occurs because a very large capacitor , is not able to charge and discharge
in the same velocity of music transitions , thus generating distortion .
To minimize the blocking effect , I use a cap. calculated for a - 3dB cut off
at + / - 10 Hz
Of course ,
Ck = 1 / ( 2 . pi . f . Rk ) , where :
Ck = cathode by-pass capacitor value ( in Farads )
pi = always the same 3,1416
f = the low - 3 dB cut off frequency , in this case 10 Hz
Rk = Value of cathode resistor ( in ohms )
( 1 Farad = 1,000,000 uF )
It is not an EXACT method to calculate Ck , but the total error won't be more than 3% .
Regards ,
Carlos
Ck = 1 / ( 2 . pi . f . Rk ) , where :
Ck = cathode by-pass capacitor value ( in Farads )
pi = always the same 3,1416
f = the low - 3 dB cut off frequency , in this case 10 Hz
Rk = Value of cathode resistor ( in ohms )
( 1 Farad = 1,000,000 uF )
It is not an EXACT method to calculate Ck , but the total error won't be more than 3% .
Regards ,
Carlos
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