Reverb idea....... new????

[Bernardduur]

Hey all!

I just finished my build of a Fenderish small combo, 1x12" from an old Dynacord Twen combo.

I wanted to add a reverb but I noticed that when you use the Fender / Princeton values of reverb you cut a LOT of volume. In the Twin reverb kind of amps you get another gain stage to cover the loss, in the Princeton there is none.

After some experimenting (lowering the value of the 3M3 resistor) I got little reverb, not just right............. OR I got little reverb, OR I got too little volume!

So I changed the input of the reverb to the first tube stage just before the tone stack and changed the 3M3 into a 100k

And voila; TONS and TONS of reverb........... and TONS of volume!!! GREAT!

Is this ever done before?????

[jpfamps]

That seems like a very cool mod.

I've not seen this done before.

That statement, of course will probably precipitate an avalanche of replies from people who have "been doing it for years"................

[txstrat]

Sounds very interesting. Where do you feed back in the reverberated signal? Just before the tonestack as well? Could you post a schematic?

[tubeswell]

Yes its been done a lot over the years. The 3M3/470k(+ 100k pot) voltage divider which is used to mix dry and wet signal strengths in the BF fenders is a cheap way of knocking out gain from the dry signal, and lots of people muck around with it. Another option is to increase the size of the (470k + 100k pot) 'leg' resistances.

[Bernardduur]

Nice!!!!

Preamp:


Poweramp

[AmpRX]

What computer programs do you guys use to draw schematics?

[Bernardduur]

I use Splan 6.0

[AmpRX]

I was involved in the design of the AC30HW. It was a hand wired, one channel (Top Boost) AC30 with Tremolo and Reverb. The Reverb drive was taken from the equivalent of the junction of R8/P2/C4 because it had a detrimental tonal effect on the direct signal taken from other spots. The return was connected to the side of the phase invertor not being used. Have you noticed any tonal changes by adding the drive where you have it?

[Alf]

I just finished my build of a Fenderish small combo, 1x12" from an old Dynacord Twen combo.

What tank did you use ? I'm curious,, long or medium ?

Alf

[Bernardduur]

I was involved in the design of the AC30HW. It was a hand wired, one channel (Top Boost) AC30 with Tremolo and Reverb. The Reverb drive was taken from the equivalent of the junction of R8/P2/C4 because it had a detrimental tonal effect on the direct signal taken from other spots. The return was connected to the side of the phase invertor not being used. Have you noticed any tonal changes by adding the drive where you have it?

The amp sounds the same without the reverb as with the reverb........ I retain the volume it has and sweet spots I know of. By useing other places to drive the reverb I noticed a slight volume cut and a tonal change that I didn't like...........

The reverb sounds awesome btw

[Bernardduur]

What tank did you use ? I'm curious,, long or medium ?

Alf

I used an old Hammond reverb tank I had laying around

[Alf]

So you didn't pay attention to the impedance it just worked out well for you ?

I wasn't so lucky with my Guyatone where I replaced the original badsounding tank with a Accutronics but didn't like that sound either. Must have done something wrong but haven't had the time to correct it so far.

[Bernardduur]

I copied the Hammond reverb section (simple gainstages, no transformer) and it works brilliantly!

[txstrat]

I copied the Hammond reverb section (simple gainstages, no transformer) and it works brilliantly!

That sounds even more interesting. Mind to share the schematic?

[riz]

@txstrat: unless you want the original Hammond schematic, he already posted his schem--scroll up!!