wierd eq

[jestaudio]

Finaly got rid of most of the gremlins on my Champ build apart from the lack of bass control, double checked everything, treble works fine but the bass hardly does anything, the scheme is attahed

[tictac]

Try changing the value of the 15k on the Bass control. Fender usually put a 6.8k in there... it will change the way the bass control responds by dropping a bit more of the mid-range frequencies; you should notice more of a diffrence in the extreme settings of the control...

TT

[Firestorm]

Try changing the value of the 15k on the Bass control. Fender usually put a 6.8k in there... it will change the way the bass control responds by dropping a bit more of the mid-range frequencies; you should notice more of a diffrence in the extreme settings of the control...

TT

I agree. You could also (or instead) try changing the tone cap values to 22n and 22n, instead of 100n and 47n, which will shift the frequencies controlled by the bass pot a little higher so you can hear more of the effect.

Be aware that the lack of bass response in the Champ circuit is deliberate: the amp wants to hum like hell at 60Hz and 120 Hz (single ended, so no phase cancellation) so limiting bass response "cures" it.

Your output transformer likely doesn't do very well with low end, so there's a bit of a limit in how low you can go with stock parts.

[jestaudio]

Try changing the value of the 15k on the Bass control. Fender usually put a 6.8k in there... it will change the way the bass control responds by dropping a bit more of the mid-range frequencies; you should notice more of a diffrence in the extreme settings of the control...

TT

I agree. You could also (or instead) try changing the tone cap values to 22n and 22n, instead of 100n and 47n, which will shift the frequencies controlled by the bass pot a little higher so you can hear more of the effect.

Be aware that the lack of bass response in the Champ circuit is deliberate: the amp wants to hum like hell at 60Hz and 120 Hz (single ended, so no phase cancellation) so limiting bass response "cures" it.

Your output transformer likely doesn't do very well with low end, so there's a bit of a limit in how low you can go with stock parts.

Cheers, did a litrtle playing around and found 22nf/47nf works well as a compromise, 22n/22n played havoc with the amp with all sorts of wierd and wonderfull issues, sound pretty good now and i reckon the Hammond OT is as agood as it gets for the money.