i want to turn my ax84 p1 that i never got finished building and want to know what changes i need to make in order to turn it into something more like a champ. (1 gain stage, vol control only)
here is the schem of the p1
http://annex.ax84.com/media/ax84_m311.pdf
here is the schem of the champ
http://schematicheaven.com/fenderamps/c ... _schem.pdf
by design, they are similar up until the tonestack.
is there anything wrong with bypassing the tonestack and then after c13 (which is changed to a .022) remove r9 and add in the 220k to ground leaving the rest as is in the p1 schematic.
also can i make the 22k off the OT a 25k presence knob?
want to turn ax84 p1 into fender champ.
Moderators: pompeiisneaks, Colossal
Re: want to turn ax84 p1 into fender champ.
If you truly want a Champ, there are quite a few changes to make. Starting at the input moving through the signal path...
1) Replace R24 with a 33K (the champ has 2 68k's in parallel)
2) Remove C16. Keep it around, you might like the way it sounds.
3) Remove R19, R20, and C13, connect the volume control directly to V4 pin 2
4) Remove C12, but again you might like the way it sounds so keep it for testing
5) Remove the tone stack and master volume, replace it with a .022uF from V4 pin 1, and a 220k to ground on V1 pin 5.
6) Replace R10 with a 470R/3W and C7 with a 25uF/25V
That takes care of the signal path. Some of the power supply may be off, but leave it unless it simply doesn't have that Champ feel.
1) Replace R24 with a 33K (the champ has 2 68k's in parallel)
2) Remove C16. Keep it around, you might like the way it sounds.
3) Remove R19, R20, and C13, connect the volume control directly to V4 pin 2
4) Remove C12, but again you might like the way it sounds so keep it for testing
5) Remove the tone stack and master volume, replace it with a .022uF from V4 pin 1, and a 220k to ground on V1 pin 5.
6) Replace R10 with a 470R/3W and C7 with a 25uF/25V
That takes care of the signal path. Some of the power supply may be off, but leave it unless it simply doesn't have that Champ feel.
Re: want to turn ax84 p1 into fender champ.
great. thats just about exactly what i did. would the 25k presence knob work well? i dont have a 22k resistor on hand. im not going for exactly a champ, just something that is more "champ- like" than the p1. ill try what you have posted. thanks.
Re: want to turn ax84 p1 into fender champ.
should be done with all this tomorrow. have all this extra real estate. wonder what else i can add.
is it possible to do a 4 input champ and have a bass and treble channel with only 2 volumes like a marshall does? i have another 12ax7 socket space unused but not sure how they'd be combined
is it possible to do a 4 input champ and have a bass and treble channel with only 2 volumes like a marshall does? i have another 12ax7 socket space unused but not sure how they'd be combined
Re: want to turn ax84 p1 into fender champ.
just finished. it worked. now i guess ill mess with values to get the tone i want but it sounds pretty good as is. running on an el34 now so i might order a 6v6.