To Anyone Who's Messed Around With Filter Caps

[fiftynine]

Did you notice anything going from 16uf across the board to 20uf in a Deluxe Reverb? What about 8/16uf's (Vox) to 22/33uf (Matchless)? Less hum? Feel stiffer? Too strident?

[Scsoul]

    Yo u won't notice it much Yo u may notice if Yo u jumped from 32uf to 80uf,  but from 16 to 20 or 10 to 16, I don't think so

[robrob]

I agree, 16 to 20 is a small step and you probably won't notice a difference.

[pompeiisneaks]

Yeah I just saw a thread on TAG where someone in the know said they can vary drastically for Ecaps, sometimes up to +80% -20% so that little of a difference should not matter.  the only concern I can think of would be to be very careful of caps directly after a tube rectifier.  The data sheets specify the maximum cap rating the tube can handle, or you'll end up killing it.  You could start with that rating and then put a choke/resistor after and then go much higher as needed if designing I believe.

~Phil

[12AX7]

I never notice anything till i at least double/half the value. Even then it's slight. Quadruple get very noticeable like going from 20 to 80uf or visa versa.

[fiftynine]

12AX7, what do you notice?

[pompeiisneaks]

I think it was sluckey here that once told me if you increase the capacitance you get a slightly better bass response 'maybe' and that probably depends on a lot of other complex variables about the entire amp's signal path :)

~Phil

[Ed_Chambley]

With the Vox changing from 8uf to 16uf in the 15 watter will make a noticeable change in the preamp, but this is double.  Personally, I think it kills the amp's touch.  Another double is in the Princeton Reverb.  The first cap is 20uf and a lot change this to 40uf and it does make a difference in bass.  It becomes more firm.  Very common.  I prefer it here.


Some of the differences between the Bassman which was what Marshall began with were increase in filter caps and finally SS rectification with even higher filteration.  I sort of think of it this way.  Any amp the has the greasy feel usually has less node capacitance as well as a tube rectifier and some sort of sag.  They tend to have a spongy feel.  Moving in the other direction quickens the attack which is very beneficial if you can play fast and like an over driven tone.

[alerich]

I doubled the value of the first filter cap from 22uf to 44 uf (tacked in another 22uf in parallel) on my Fender Princeton Reverb RI. It improved the sound of the low notes in the amp. That amp is notoriously farty on the low end and the added reservoir helps clean that up a bit. Be careful adding more capacitance like this to a tube rectifier. Make sure it is up to the task. The PRRI uses a GZ34 so no problem there.

[Willabe]

I doubled the value of the first filter cap from 22uf to 44 uf (tacked in another 22uf in parallel) on my Fender Princeton Reverb RI. ........... The PRRI uses a GZ34 so no problem there.

Just to be clear for the new guys, no problem with adding 22uF.

There would be a problem with adding a larger value, like 100uF or more.

[Tony Bones]

To add one more comment that I didn't see already mentioned in this thread (though I might have missed it) is that you can add more capacitance to the second stage - after the choke or first resistor - and gain the same benefits without taxing the rectifier quite as much.

You don't have to believe me; just try it yourself. 

[Ed_Chambley]

To add one more comment that I didn't see already mentioned in this thread (though I might have missed it) is that you can add more capacitance to the second stage - after the choke or first resistor - and gain the same benefits without taxing the rectifier quite as much.

You don't have to believe me; just try it yourself. 

I believe it cause I have done it and will again Tony Bones.  Where does the Bones come from, real name or dice player?