Splitting Deluxe Reverb signal

[JoeK]

I've built my Weber Deluxe Reverb a few times now. It started as the usual two channel with a modified Normal channel tonestack. Last version is a single channel amp with reverb and bias tremelo. It's last incarnation is based on Doug Hoffman's AB763 single channel.
I'm just thinking "what if?" I sent the reverb return back on it's own feed to the phase inverter. I'm only using one side of the phase inverter as is and I'd be able to lose the mixing resistors (220K-220K) and the 20pf-3.3M blend? at the reverb return? Looking for other builds that have had this arrangement but I've only seen the Matchless Chieftan with a separate reverb feed to the PI. I have a spare noval socket in the amp at the moment.
Would there be any pro's to separating the feeds or should I just leave this well alone and be happy with what I've got?
Here's Doug's build(with a normal channel):
http://www.el34world.com/Hoffman/images/AB763Old.gif

and a Fender schem:
http://www.el34world.com/charts/Sche...b763_schem.pdf

[Tom Phillips]

Do you have that available to show in schematic format?

[JoeK]

I updated the links. The AB763 schematic is the circuit I have in the amp at the moment (sans Normal Channel) but now I've looked at it again I think I'm just getting confused. I thought the normal channel was on one side of the phase inverter and the vibrato channel on the other side.
So maybe I should ask my question again and say is it going to give me any bonus if I remove the blending of the vibrato channel and reverb return? I could boost the reverb return with the spare triode/s and send it into the phase inverter on the other side?

[MWJB]

If you only have one channel you don't need the 220K mixer resistors. Eliminating the 220K resistor will boost gain some. On the stock AB763 both channels feed the same point on the PI, both on the "same side".

[Tom Phillips]

...So maybe I should ask my question again and say is it going to give me any bonus if I remove the blending of the vibrato channel and reverb return? I could boost the reverb return with the spare triode/s and send it into the phase inverter on the other side?

Joe,

I don’t think there is any compelling reason to move the reverb return to the PI. The real question is “What sonic change are you trying to accomplish.” Mods don’t always change just one thing. Often a tweak somewhere else is required to give you the final sound you want. You need to be careful that your initial change doesn’t screw up something else. If you are not installing a “tried and true” mod you need enough understanding of the circuit to keep yourself out of trouble.

Note that the channel mixing and the dry signal/reverb mixing in the stock ‘vibrato’ channel are two distantly different parts of the circuit. The dry signal/reverb mixer also includes EQ.

So we come back to the question - “What do you want to accomplish?”

Regards,
Tom

[pdf64]

Plus using the 'other' phase splitter input will affect up the power amp global negative feedback loop. Not sure exactly what would happen but stock, that input is a rather low impedance, so you may need to buffer it etc.
If you're running without global NFB, as per 18 watt, then either phase splitter input should be fine. Pete.

[JoeK]

Thanks for your replies I've been off line for a few days so a delayed response. Hmmm the negative feedback didn't enter my thoughts until you mentioned it. It would seem that there is no bonus for separating the reverb return in this amp so I better head back to the tried and true.