# Adding spring reverb unit to tube amp?



## JPitt (Mar 3, 2010)

Hey guys,

Just wondering, does anyone have any experience in adding a spring reverb tank (e.g. an accutronics-type unit) to a tube amp? I'm getting an AC30 hand-wired and just debating doing a few mods and think that adding reverb "should" be a relatively easy addition.

Anyone that can point me to a source of info, that would be awesome. 

Cheers,
J.p


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## TWRC (Apr 22, 2011)

I could be wrong here, but adding a reverb unit to an AC30 will be a very tall task. Not only that, you'll probably alter the tone a bit by doing so. If reverb is a must have, I would suggest an outboard reverb unit like a Fender one or even a reverb pedal.

Another thing is to find an AC30 with reverb. My old AC30 has reverb and honestly, I don't play with the reverb on the amp at all.


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## Wild Bill (May 3, 2006)

JPitt said:


> Hey guys,
> 
> Just wondering, does anyone have any experience in adding a spring reverb tank (e.g. an accutronics-type unit) to a tube amp? I'm getting an AC30 hand-wired and just debating doing a few mods and think that adding reverb "should" be a relatively easy addition.
> 
> ...


It is a bit more than you might think. The actual spring unit is the easy part!

You will need 2 more tubes, with sockets and parts. One will develop the power needed to feed into the springs. The other will recover the reverb signal at the output, boost it back up to a useful level and then mix it with the original "dry" signal.

I'm unaware of any specific circuit to add in to your AC30. So if you don't have the background yourself you need a tech with enough knowledge to whip up a circuit on his own and wire it in.

Or, the suggestion from TWRC to go for an outboard unit is a good one! They sound beautiful and have more knobs for adjusting the tone. I've done a number of them over the years and guys love them, especially jazz players.

Wild Bill/Busen Amps


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## J-75 (Jul 29, 2010)

+1 to TWRC & W.B.

Don't go there - you could be ruining the sound and value of the AC30.
A Fender Reverb would be an excellent choice, or for less $ and weight, try one of the better pedals out there - start with a TC electronics (Nova?) and go upstream if that one doesn't impress you.


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## Milkman (Feb 2, 2006)

Yup. It's a much better idea to go with a pedal IMO. A tank in a head will give you varying amounts of one basic effect.

Any decent modern pedal will give you a selection of reverbs, some of which are ridiculous, but at least a few of which are cool.


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## nonreverb (Sep 19, 2006)

Hate to be a hellion but you could install an organmate reverb unit...they were developed for Hammond B3's, use tubes and the whole preamp section rides piggyback on the tank. I'm not totally sure what tube you'd insert it between but I know it would work. Heck it might work in the effects loop although the impedance might be a problem...


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## mhammer (Nov 30, 2007)

I'm not sure what "handwired" means in your context. Is somebody making you an AC30 clone? If so, then I imagine they _could_ add the requisite circuitry. It should be expected to up the price noticeably, however.

Is a reverb pedal a reasonable substitute? Not in my view. Reverb corrupts the signal, albeit in a nice way. Adding reverb after the front end of a preamp has been pummeled can be very nice. _Feeding_ a pre-reverbed signal to pummel the front end of an amp can be, in Alfred E. Neuman's immortal words: Blechh

So here's the less costly, and tonally better alternative: get your builder to insert an effects loop, and patch the reverb pedal of your choice into the loop.


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## dtsaudio (Apr 15, 2009)

If he's trying to clone the AC30 reverb circuit, good luck. He'll need a 12AT7, a 12AX7 and a transformer. The transformer actually is run push/pull on the primary side. It's an odd arrangement and doesn't work very well. If you need the schematic shoot me an email.
I like mhammers approach, put in an effects loop.


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## WCGill (Mar 27, 2009)

This is a major undertaking that will have a serious impact on the value of your hand-wired beauty. Not at all worth it.


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## JPitt (Mar 3, 2010)

Hey Bill,

This was the answer I was looking for! I was semi-thinking of a small outboard unit that I could put in the bottom of the cab with some basic controls. 

I was thinking of a little solid-state (op-amp) based spring reverb that I could implement and reuse a reverb tank that I have kicking around. Seeing everyone's response here makes me think... it's more complicated than I first thought. 

Really appreciate the input guys, and letting me know that I'm crazy to even be debating trying this. I do think mhammer is on to something... an effects loop!! That's a brilliant idea. I think throwing an EHX nano grail in there would do nicely. I've just never had a very good experience with reverb pedals on my pedalboard and debating other ways to include it (just because I really do like a touch of reverb for certain things). 

Thanks for all the suggestions guys... I'll post again if I make any head-way on this.
Cheers.



Wild Bill said:


> It is a bit more than you might think. The actual spring unit is the easy part!
> 
> You will need 2 more tubes, with sockets and parts. One will develop the power needed to feed into the springs. The other will recover the reverb signal at the output, boost it back up to a useful level and then mix it with the original "dry" signal.
> 
> ...


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## JPitt (Mar 3, 2010)

This is what I was initially thinking of... not a tube reverb, but a solid-state:









http://paia.com/ProdArticles/hotspuse.htm

Seems like a reasonable build. Add a "tap" just before the power stage of the circuit....run this through... That was my initial idea. Not sure if that would actually work or not. Just bouncing ideas. 

Appreciate everyone's input and interest on this though!!
Cheers.


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## Adcandour (Apr 21, 2013)

Just buy carl martins headroom. It's an actual spring reverb. Only set-back is the size.


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## JPitt (Mar 3, 2010)

Wow! I've never heard of that one. To YouTube I go


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