Bypass Cap on cathode?

[infernal]

What if I change electrolythic bypass cap with one block cap (same value of course)
Will it change anything?
Cap is 1uF 63V
I want to change that one in 1uF 63V metal poly (axial-yellow-cool)

Would it affect sound or something?
Maybe it is stupid question idk,

[nigelwright7557]

There are a few who would say it will modify the sound a bit but to my ears it wouldnt.

[infernal]

Ok so I would not screw up if i test it
Thanx a lot

[nigelwright7557]

Originally Posted by infernal

Ok so I would not screw up if i test it
Thanx a lot

It will be fine.

[DavesNotHere]

it wont change anything, but you will learn what characteristics of one type/brand/construction to another if you keep the same value.

Common-cathode stage, fully-bypassed cathode:

Voltage Gain:

Av = (mu * Rp)/(Rp + ra)

Input impedance:

Rin = Rg

Output impedance (plate):

Rout = (ra * Rp)/(ra + Rp)

Output impedance (cathode):

Rk' = (Ra+ra)/(mu+1)
Rout = Rk'||Rk

Input capacitance:

Cin =Cgk + Cgp*(Av + 1)

Frequency response:

f1 = 1/(2*pi*Ci*Rg) - highpass breakpoint due to Ci/Rg f2 = 1/(2*pi*Co*(Rout + Rl)) - highpass breakpoint due to Co/Rout/Rl
f3 = 1/(2*pi*Ck*Rk'||Rk) - highpass breakpoint due to Ck/Rk
f4 = 1/(2*pi*(Rout+Rg)*Cin) - lowpass breakpoint due to Rout of previous stage and Cin

Where:

Rg = the grid resistor
Rp = the plate resistor
Rl = the load resistance, or the input resistance of the next stage
Ra = the total load resistance, which is Rp in parallel with the input resistance of the next stage, Rl. If there is no Rl, Ra = Rp.
ra = the internal plate resistance of the tube
mu = the mu of the tube
Cgk = the grid-to-cathode capacitance
Cgp = the grid-to-plate capacitance
Av = the stage voltage gain

Note that Rl is ignored in the output impedance calcuations for the output, not because it doesn't affect output impedance of the overall circuit, but because output impedance is traditionally the impedance of the output of that gain stage looking back into the output. Rl is the input impedance of the following stage, so it is not included. Of course, when calculating overall gain in an amplifier, the loading effect of Rl must be taken into account. In the case of the cathode impedance, Rl must be included because it will affect the impedance seen looking back into the cathode.