BAXANDALL EQ Question....

[zozoe]

Greetings again~ I've been wondering why my Ampeg GU12's don't rock nearly as well as my AC12's.... My GU's are both wonderfully clean, but NOWHERE as 'Stones'y as the AC's once its NFB is clipped.

THEN, I just now caught a YT video, comparing the 2 amp models, & the only major diff was that the AC's had a NFB loop whilst the newer GU's removed it, BUT the guy furthur explains how ''the 2-band (treb/bass) Baxandall eq curcuit on the GU's has less gain in the front end than the single Tone circuit on the AC 's, MUCH less!!" AHA!!

Is there anything, including totally altering or replacing the Baxandall, in order to re'gain' that lost gain factor that truly disappoints & perhaps is why the GU doesn't kick arse like the AC's (w/NFB clipped!)??
Many thanks~

[Stevem]

So why are you looking to have two amps that can do the same thing.

[zozoe]

Backup.....
about my Baxandall question?

[TUBEDUDE]

It does load the signal much harder than.a single tone control, ie. high filter.
Maybe you could try a tilt control to.get what you need and preserve gain.

[zozoe]

It does load the signal much harder than.a single tone control, ie. high filter.
Maybe you could try a tilt control to.get what you need and preserve gain.

Is it a difficult, overly invasive conversion for a tech (not me) who knows his stuff? Tilt Control?? Not familiar..
Thnx, Kenny ॐ

[Bergheim]

It does load the signal much harder than.a single tone control, ie. high filter.
Maybe you could try a tilt control to.get what you need and preserve gain.

Is it a difficult, overly invasive conversion for a tech (not me) who knows his stuff? Tilt Control?? Not familiar..
Thnx, Kenny ॐ

A tech who knows his stuff should be able to do this without any problem. The tilt control is a one knob control, so it'll leave you with a unused hole in the front panel. I'd rather try to increase the gain downstream, for example bypassing the phase inverter driver stage cathode resistor (R25), or decreasing the reverb mixing resistor (R23).

[lonote]

I've been wondering why my Ampeg GU12's don't rock nearly as well as my AC12's.... My GU's are both wonderfully clean, but NOWHERE as 'Stones'y as the AC's once its NFB is clipped.

I can't offer any insights other than the AC has the much simpler tone control. But I am not familiar with either of those amps & only pulled up the schematics due to your query.

I have never built a James-style tonestack, but I am wondering if lifting the tonestack ground reference would have a similar bypass effect, as it does with the Fender TS..? I know when the ground is lifted with the Fender circuit, the tone stack is minimized/nearly bypassed & it passes more signal onto the next stage. Might be what you are looking for? Maybe the more knowledgeable will weigh in.

But, they are both pretty interesting amps & as you play through them both, I had some questions, as I might borrow some ideas from them.

Do you find the AC tone circuit pretty usable for guitar? (I think it was actually meant to be an accordion amp) Do you like the reverb? Typical spring tank? (just says "echo unit" on schematic)


Thanks in advance

[Stevem]

On Ampeg schematics they call the reverb tank a echo unit which to me is not quite as bad as Fender for many decades now calling tremolo a Vibrato function right on the amps front panel.