Coupling capacitor technical question

[audiophool]

Hoping for some guidance here from one of our technical members 
Input to my integrated amp passes from volume control through a capacitor to a pair of resistors, one to ground and one to the grid of the input side of a cascoded triode pair.
Current cap value is 0.33 uf, resistor to grid is 4K7 and to ground 680K.
Question is, what will be the effect of changing this capacitor value ? perhaps to 0.47uf ?
TIA
Tony G

[data]

That cap is intended to block DC, a filter if you will, I think...

The net effect might be nothing, but myself i would stick with the value the designer has used. Changing it to another cap.. of better quality might gain you something, but whether you prefer the sound signature of not, is another question.

What is the amp?

And what is the cap in question?

[zenelectro]

Hoping for some guidance here from one of our technical members 
Input to my integrated amp passes from volume control through a capacitor to a pair of resistors, one to ground and one to the grid of the input side of a cascoded triode pair.
Current cap value is 0.33 uf, resistor to grid is 4K7 and to ground 680K.
Question is, what will be the effect of changing this capacitor value ? perhaps to 0.47uf ?
TIA
Tony G

The cap is to block any possible DC coming from the input.

You can pretty much bypass (remove) it. 

The only other possibility is if the tube is running intentional grid current bias. I doubt it but some designs
do use this so better check. Get an ohm / volt meter and check what the DC voltage reads at the tube side of the cap
(with the amp on).

If it's 0 volts, then bypass the cap.   

[audiophool]

Thanks for that guys, firstly, I have already replaced the originals with same value capacitance but much higher voltage rated (because that is what I could get) AmpOhm Cu - they were an improvement when they finally burned in (took looooong while) and was toying with the idea of Duelands but they only come in 0.1 or 0.47 - thought to get away with the 100V jobs since circuit diagram only specifies 50V.
Will measure as suggested, perhaps bypassing it will prove even mo better.
Make and model of amp would not help since it was a prototype and varies from the provided circuit diagram in several respects anyway.

[kajak12]

Thanks for that guys, firstly, I have already replaced the originals with same value capacitance but much higher voltage rated (because that is what I could get) AmpOhm Cu - they were an improvement when they finally burned in (took looooong while) and was toying with the idea of Duelands but they only come in 0.1 or 0.47 - thought to get away with the 100V jobs since circuit diagram only specifies 50V.
Will measure as suggested, perhaps bypassing it will prove even mo better.
Make and model of amp would not help since it was a prototype and varies from the provided circuit diagram in several respects anyway.

You can get custom duelund caps to value needed if your prepared to wait usually about 6 months

[audiophool]

Thanks for that info K, not a preferred option though (for me ATM).