OPT driven reverb into second amp input

[phred]

Hi, new to the forum and it looks great.
Toying with an idea and looking for feedback on some questions.

I have built an AX-84 P1 (single 12AX7 - pretty clean sound) and and AX-84 P1 extreme (2- 12AX7 stages) along with about a half dozen other projects some of which involved harvesting parts from some old organs.
One piece from that harvesting is a reverb tank with 8ohm input and 2250ohm output (~50ohm dc R) that I want to use.

Here's the plan:
Use the P1-extreme to drive the reverb tank (along with its speaker) and then use the P1 as the reverb recovery amplifier. This is similar to what is done in a Hammond M-111 organ as there is a separate amplifier off the reverb tank.
Add an L-pad (speaker attenuator) before the input to the reverb tank - this would allow me to control how hard the reverb tank is driven separately from how loud the amp is turned up.
Take the reverb tank output to the input of the AX-84 P1 amp & speaker. Giving me tone and volume control of the reverb signal.

1) Anyone done something similar? How did it go?
2) Any thoughts on whether the L-pad (driving the reverb tank) should be in series or parallel with the amplifier speaker.

Rough block diagram of series/parallel options attached.

[LOUDthud]

The flaw in this whole thing is that a Reverb tank only needs something like 0.5 to 0.1 Watts and that's all the power it can handle. An L-Pad is going to waste at least half the power of the driving amp. It would be better to build a resistive attenuator to drive the tank without loading down the driving amp too much. Also, Reverb tanks can't handle very much bass. A series capacitor is needed somewhere on the drive side to limit the bass drive.

[FUCHSAUDIO]

Take at look at Ampeg and/or Gibson-Maestro, both of whom drove reverb pan inputs with speaker outputs. I think the Super-Echo-Twin amp did this. The Gibson/Maestro units had alligator clips and you could connect to your primary amp and they had a reverb pan and a small power amp to add reverb to an existing rig. You just need to pad down the hell out of the amp output to not overdrive the reverb input transducer. The output of the pan can be amplified by a simple guitar amp like circuit.

[two tone]

I‘ve been doing this for some years now. Add a resistor between the speaker out and the reverb in( 50/100ohm in series) .This isolates the reverb from the amps output impedance. I‘m running 50 w amps at stage volume into the reverb pan feeding a small satellite amp( 5-10w) . Dry/Wet system

[Stevem]

These days I would much sooner if I was building a amp from scratch use a IC based reverb section.

All they need is 5 volts and very little current and you never have to be concerned with having a spring bust or a transducer going open, and needless to say they sound much better!

[sluckey]

The Hammond M100 with AO-44 reverb amp used a simple compressor circuit between the main speaker and the input to the reverb tank to keep the signal level at a kinda safe/constant level.

[Andy Le Blanc]

Thats an echo jet. Its a "F" type verb tank, the Input from the speaker + is a RC filter, 300 to 1k paralleled by a large value 50uf (you can play with the value) non-polar cap. You can plug the out put into any thing, any second amp. I've built that one. Fun to gig with, the effect is more of a "dimension" rather than a "verb" effect,... a ghostish depth, Maybe best described as a plate delay sound.

[phred]

Hi, thanks for all the great feedback.

In no particular order - some thoughts.
1) agree the L-pad would rob 1/2 the power, but on the flip side the amp has enough for use as practice and maybe I can get more tube overdrive without driving others out of the house.. thought the flexibility of how much drive I send to the reverb tank would be nice - esp for a first try. If it kills too much then I can go for a different isolation technique.
2) I had seen the compressor bridge in the M100 manuals - I may still look into that as well as it would be nice not to get all 'muddy' with too much reverb if you turn up the clean channel a bit, dig up the right light bulb sizes..
3) I have some nice large caps left over from some cross over builds - I'm assuming I can treat that like a simple 2-way cross over / high pass filter - tuned more for a midrange. Nice idea to limit the bass/mud a bit and likely easier on the input transducer too.

Here are a couple of the little AX-84 P1-ext practice amps I'll be doing this with - the reverb tank will just fit into the back of the darker one.

[phred]

Update: Proto typed out the L-pad idea wired in parallel (easier to cobble in) switching to the 4ohm output on the input amp.
The Lpad lets me go from barely noticeable to too much (starts sounding hollow/tinny and 'over effected' to me), and then using the second/recovery amp you can also mix in the level.
You get a bit of a dwell vs volume control and very much a verb effect. - Happy camper and I can still get plenty loud (according to my wife)