Tube Practice Amp Adding Reverb

[olddawg]

Honestly... get a pedal. You won’t like an integrated reverb in a 10 watt amp after all of the trouble.

[Wolfman88]

Honestly... get a pedal. You won’t like an integrated reverb in a 10 watt amp after all of the trouble.

Read what I'm doing the 10 watt is being converted into a tube preamp for a bigger solid state amp.

[Chuck H]

Read what I'm doing the 10 watt is being converted into a tube preamp for a bigger solid state amp.

That's actually just what he's doing. Since the tube amp is the preamp it makes more sense to put effects BETWEEN the pre and power circuits in any rig. Incorporating reverb into the preamp, in this case, could mean that the reverb gets garbled by distortions in the amp before being reamplified by the slave amp. If you add reverb to the system creating any distortions then the reverb suffers that distortion also. Better to place the reverb between the two circuits.

[Enzo]

I think someone hinted at it, but if this whole amp is to be used as a preamp, might it not be simpler to put a load resistor in place of the speaker, use a voltage divider across it to make a line level out for some power amp and ALSO drive a reverb pan directly off the speaker circuit. Then a simple recovery stage at the reverb out, and mixed into that line out, et voila.

[Wolfman88]

I think someone hinted at it, but if this whole amp is to be used as a preamp, might it not be simpler to put a load resistor in place of the speaker, use a voltage divider across it to make a line level out for some power amp and ALSO drive a reverb pan directly off the speaker circuit. Then a simple recovery stage at the reverb out, and mixed into that line out, et voila.

That's what I'm planning turning the speaker out into a line out.

[Chuck H]

Another upside is that the tremolo would be preserved.

In this case, with the Silvertone modified to put out a line level signal, a simple reverb pedal or any other self contained effects unit could be used.

The line out and dummy load are really simple. But can you first tell us how you're currently connecting the Silvertone to the Kustom.?.

[Enzo]

I know you want to make a line out, but have you considered driving the reverb from the speaker out too? Hammond did that in their organs, and other amp makers have as well. It would mean you can leave the amp intact, just add a small recovery circuit.

[eschertron]

We haven't talked about form factor or portability.
Wolfman, you could build a stand-alone reverb unit if you're dead set on building something. Otherwise consider that while re-purposing the trem for reverb sounded like a good idea, it might be time to pivot and go with another plan that doesn't involve so much sweat and tears.

[Chuck H]

I know you want to make a line out, but have you considered driving the reverb from the speaker out too? Hammond did that in their organs, and other amp makers have as well. It would mean you can leave the amp intact, just add a small recovery circuit.

I think we're on a couple of different paths here now. g1 suggested driving the tank from the little amp. That'll work great, but would require about 50x to 100x amplification of the output of the tank before it would provide a useful signal to another device. Little amplifiers that would do this aren't hard to make or even buy. But we still have the matter of using the Silvertone as a preamp as well. So we would need a circuit at the Silvertones output that would drive the tank and provide a 1V dry signal, a preamplifier at the output of the reverb tank with variable output and then a circuit to combine the wet and dry signals. And this still isn't ideal because the reverb would be first in the chain if any other effects were used. It should be last in the chain if possible.

I think the easiest route would be to put a dummy load and line out at the Silvertone's output to provide a line level signal. Then Wolfman could run ANY effects he wanted to (including any analog or digital reverb) between the Silvertone and the Kustom.

This would also be an economical route. Only a few dollars for resistors (and easy to build). Adding reverb to the Silvertone would require a tank, a transformer and a tube (not to mention considerable labor) and driving the tank from the Silvertones output would require a tank, a preamp circuit and probably a box to contain it all (though a bit less labor). I'm pretty sure a used signal processor with decent reverb could be purchased for the same expense or less. The overall system would be more versatile and much easier to implement.

But we still need to know how Wolfy is connecting his amps now.?.

[Enzo]

He will need to add and house a tank either way. He wants to lose the trem? OK, there is a free 12AX7. A simple recovery circuit, ala Fender et al, could be right there onboard from that tube. A couple mixing resistors in the line out circuit, not unlike the old Fender outboard reverb mix, and there you go. I am trying to keep in my mind that he wants to make this out of the SIlvertone, though that would not be my personal choice of direction. SO he is stuck with the reverb being in this position vis a vis more FX units afterwards. Yes, I would prefer the reverb being the last FX in line, but he won't get that choice building on the Silvertone. (Assuming further FX units)

SO my last pitch: driving pan from speaker out saves a drive circuit, and existing trem tube makes recovery circuit.

[eschertron]

my last pitch: driving pan from speaker out saves a drive circuit, and existing trem tube makes recovery circuit.

Don't bench yourself just yet!

Does the recovery tube go to a second output jack, then maybe to a second input on the Kustom amp (assuming there is one)? I don't think I'd want to be in the room when Wolfman fires up an amp where the output drives a spring reverb that returns to the power stage of the same amp. I imagine that could make a helluva racket!

[Enzo]

No, in my mind, I see the SIlvertone output driving the reverb pan as well as a line out. The pan recovery then mixes into the line out, not back into the amp. SImple resistors like that old Fender.

[Wolfman88]

My plan is to put the input jack on the Silvertone where the original input I use on the Kustom then convert the speaker out on the Silvertone into a line out and solder the leads to where the original input goes on the board of the Kustom. I'm still waiting to find out if the circuit board on top of the Accutronics tank is an amp for the reverb and will save doing all the custom wiring.

Can anyone here tell me if its an amp on the Accutronics it has a few different kinds of caps a pot bunch of resistors and a few transistors 2 of the transistors have heatsinks. I put up a pic in a earlier post.

Also if I'm not using the trem for anything I would like to remove the circuit tube and all to simplify the preamp hopefully I can remove it without affecting anything. On 2nd thought can I use it as another preamp tube? Keep the tube but make it another preamp tube if it can be done easily.
And what resistors would I need and anything else to convert the speaker out into a line out?

I'm hoping the circuit board is an preamp for the reverb it would be solid state but would save me all the custom wiring.

[Wolfman88]

Ok guys the circuit board is the reverb driver and preamp can I use this?
This is the reply that named the pins.

It is the tank driver and receiver circuit.
Pins 4,5,and 8 are ground.
Pin 3 25Vdc.
Pin 6, 7, and 9 inputs.
Pins 1 & 2 output.
Takes about 1Vac at the input and has a pot on the board to adjust the output level.

[Wolfman88]

Where did everybody go? I now know I have the preamp and driver for the Accutronics reverb tank. Just have to figure out how to run everything.