Spring 'verb


I have a spring reverb from an old Heathkit guitar amp - the amp proved beyond repair, but I saved this - what do I need to do to make it into a rack unit that I can stick in an effects insert? Anything?

If I remember correctly the unit in my old guitar amp had an op-amp in front of it it then some other circuitry to blend it back into the signal at the back.

I can get the guitar amp schematic if it’s gonna be of any help.


Does this link help ?

Yep… you’ll need a driver in front and a blend/buffer behind and possibly another amp stage. Different tanks will need variations in the above. If you can find specs on the tank it would probably help a great deal in figuring out what you need. OR you could just drop a hunnert bux on a good pedal 'verb. :O


Hey, D., why spend money when I can make a mess of it and then spend more money fixing it?

Thanks for the link, Wihan. I don’t know if that project quite fits the bill, since it is for guitar, and I want to tick the verb in a box and rack mount it. But I now understand in general what would be needed.


Good link Wihan.

TomS, Basically, all you need is a small audio amp to drive the unit and a pre-amp to buffer the signal at the other end.
The circuit shown in the link is just that, so I suppose you will already have the necessary equipment lying around in your studio, i.e. a headphone amp and a mic pre.

I would be tempted to try and drive it from the mixer insert send / return directly, without any gubbins in the way. It might work, you certainly won’t trash anything. Most likely thing is that the effects send will not have sufficient drive, so then you could stick the headphone amp in circuit and try again.

Happy fiddling :D


Perfect - I have a berry headphone amp and an art MP preamp - those work?

But…as long as it won’t hurt it to try, I’m going to just plug it in and see what happens first.


Don’t see why not.
Just make sure that the pre is not one with phantom power to the microphone input.
Not that it should damage anything, as the available current will be limited anyway, but it will saturate the spring driver and cause some weird funkiness (technical term)
If the pre is phantom power, wire a capacitor in series with the signal lead. That will block the DC but let the AC signal through. Try 0.1uF as a starting value if required. Smaller values will roll off the bass, larger values will let more bass through. Adjust to taste.


Well, just sticking it in the insert didn’t work too well, predictably, although at a very high gain setting it passed some signal. Tomorrow I will try it with a headphone amp in front of the springs. Hey, I wonder if it would work with one of those cheap “Honeytone” guitar/headphone practice things, like a cheap rockman. 'Cause then I could also put some distortion on it. :) That might be fun.

Quote (TomS @ Dec. 13 2006,19:11)
Hey, I wonder if it would work with one of those cheap "Honeytone" guitar/headphone practice things, like a cheap rockman.


Yep, that should work.
The amp shown in the circuit in Wihans link used an LM386 which is commonly used in cheap, general purpose audio devices like portable radios.
I would not be at all surprised if the Honeytone uses the exact same chip.

Build your own

Simple circuit with pcb layout and perf board layout.


Ah, perfect, the little gem and the ruby - I remember looking at those a while back, when folks were messing with little smokey and similar amps. Thanks for the link, Steve! that’s a project even I can do! :)

I got one of those lil smokey amps for Xmas last year. Can you believe those little dudes will even drive a 4X12 cab? Sure will!
Good luck Tom with the verb.

Not only that, they are a heck of a lot easier to lug around than most amp heads. So…now we need the super mini 4x10 cabinet! :D