Reverb placement

[Lothy]

Hello everyone,

since a few days I got my first tube amp back. Not the exact same one, but the same model. And a much nicer version too. It is a PCL Vintage Amp VA1956.

It was made in the early 80's, and it basicly is a Mesa Boogie MKIIb copy, with all the good and bad. The amp is in a very good condition, even the filter caps were not that far off and not leaky. I changed them anyway. The EV12S in it, is one of the best speakers I ever had.

That's how it sound as it came in (overdrive only):


One thing, I want to change is the reverb placement. The return of the reverb is fed into the overdrive stage. This sounds a bit odd to my ears. In the clean mode, the reverb works very good (as expected).

My plan is, to place it before the coupeling cap of the phase inverter. Like this.

pcl_vintage_amp_va1956_reverb.jpg

What do you think, will this gonna work? My concern is the mixing network with the 2.2M and 30p. I thought, I'll take the same as it was in the previeous implementation. Is there anything else to consider?
Thanks a lot!

Cheers
Gerhard

[TUBEDUDE]

You could ditch the feedback and send the reverb return to the phase inverter B input.
The amps I've built this way have a 3D quality to the verb.

[Lothy]

You could ditch the feedback and send the reverb return to the phase inverter B input.
The amps I've built this way have a 3D quality to the verb.

Thanks Tubedude,

I pick up the signal before the 0.1uf of V5A as shown. No resistor and cap after it. Then I fed the return into the 0.1uf before V5b.

It kinda works, but I can't turn the amp volume to 0 anymore.
And the precence control is no more active. I think there are more things to do. My skills are not so high and maybe I should leave it as is.
Cheers
Gerhard

[TUBEDUDE]

The output of V3a to the input V5b. No connection to V5a from the reverb. Yes no feedback means no presence control.

[Lothy]

The output of V3a to the input V5b. No connection to V5a from the reverb. Yes no feedback means no presence control.

Thank you,
yes, that's what I have done. But the signal has to come from somwhere to feed into the reverb. That's why I picked it up after the master volume before the coupling cap to V5A (as in my drawing).
I tried all sorts of combinations. Some of them are good for the clean tone, but as I switch on the overdrive stage, it gets weird.
I think I have to redesign the last stage of V4 like it is in the Boogie MKIIC+

mbeffectreverb.PNG

Cheers
Gerhard