How about a Reverb?

[KerryF]

So today I recieved a reverb tank from idlechatterbox.  It was dirty at first, but I gave her a face-lift:
Before:



After:




Now, I know that in reverb schematics/layouts, it says to use the In and Out wires.  Well, theres a bunch of things on each side.  Which is In and Out?  What are the other ones?  Also, what is a good reverb pedal to do for a first time reverb pedal?

Thanks, Kerry

[markm]

Wanna wet-sand some enclosures? 
Looks good buddy!

[KerryF]

Haha thanks.  I am a perfectionist, so I had to clean them up real good.  I ended up doing a pretty good job cleaning it up. .  Cant wait to use it!

[pedaltastic]

Wow! Looking at the before pictures I would never have guessed it had the potential to be that shiny! As regarding a reverb pedal I've been wanting to the Stage Center Spring Reverb for some time. You can find it at GGG:

http://www.generalguitargadgets.com/index.php?option=content&task=view&id=124&Itemid=142

I'm not a very experienced pedal builder but I reckon this would be pretty straightforward. I've already done a rough vero for the charge pump board since there's only a pcb for the main circuit.

[KerryF]

Any other reverb circuits out there?  Just want to check out a few.

[Ardric]

I like Rod Elliott's project:

http://sound.westhost.com/project34.htm

... but it needs a power supply and a little more buffering to work as a stompbox.

[John Lyons]

I see two wires on each side.
Ground is most likly green and Hot is black.
The input and output sides are labeled as on the sticker.

John

[Rectangular]

call1800:

hey, that's a nice vintage tank. I cannibalized a vintage tank from an old Hammond organ last winter. I decided to build the stage center reverb project over at GGG, mostly because it was the most readily available schematic. HOWEVER:  I didn't understand the importance of input/output impedance of a reverb tank at the time,  and realized the reason my build sounded so crappy is because the Center Stage project was designed to use a specific accutronics tank; you can't just swap any old tank. you'll have to determine what the input/output impedance of your tank is, and how it's grounded... normally there are stamped markings on the side of a tank to indicate these attributes, but even if they existed, you've clearly sanded them into obilivion 

this brings me to another question,  how would one modify the center stage reverb circuit for usage with other tank's different i/o impedances ? 

best of luck,   -Rec

[d95err]

this brings me to another question,  how would one modify the center stage reverb circuit for usage with other tank's different i/o impedances ? 

I think that a single opamp reverb driver like in the Stage Center won't be able to drive low impedance tanks. A single opamp cannot produce the current required. Some reverb drivers paralell several opamps to get more current capacity, but I'm not sure if it would be enough to drive a low impedance (e.g. 8 ohm) tank.

Several designs (like the one mentioned above) that uses an LM386 chipamp to drive the tank. I assume it should be able to deliver the current required by a low impedance tank.

Look around some of the usual DIY guitar schematics sites, there are several reverb circuits around.

[darron]

with a transducer at each end of the tank, other than ground it might not even matter which is in or out. i don't think that you'll damage it if you get it wrong? i could be very wrong.

[idlechatterbox]

I think that Darron might be right 1-800. (Of course I too could be very, very wrong!) I once took apart my Yamaha amp, and it had a long reverb tank (more like a tray than a "tank" since it was open at the top), and there really was just two springs. No mechanism or components (e.g., no resistors, diodes, etc). But, and here's the I might be wrong part, the tank you have has those weird looking "electrode" thingies on both sides, which my Yama's did not. I'm thinking your dad's drill press can solve this mystery about what's inside really fast

It will be interesting to see/hear the DIY reverb project either way. The eyes of the internet are upon you and your project, but don't let that freak you out

[petemoore]

  I forget what the elements at either end of the springs is called, but the input is a different ohmage, I don't know what else is different...anyway there is an input and an output.
  Transducer I think it's called, anyway, measure the resistances of the transducers and I think you'll see different ohmages. Might be a good idea to re-label the input and output side while you know where they are, for the next time it's needing refurbished...lol.
  I think all you need is the ohmage of the transducers, then you can find or design something for it. A 'speaker type' amp to drive the speaker like driver, then a recovery amp/mixer for reverb adjustments.
  An 'extra knob might be worth messing with, input drive control, output mix w/unreverbed signal...then...maybe a tone control of some type, if you like since you're starting scratch...
  Seems like you could use an LM386 or some other chip/amp device to match the impedances of the driver amp to the tank driver.
 
   

[George Giblet]

Copy the reverb circuit out of a solid state amplifier.

That looks like a very old OC Electronics reverb.

The later labels use to say made by the pretty girls in california or something like that.

[Mark Hammer]

Op-amps that are capable of driving low impedance loads, like the NE5532/34 or the LM833, are good choices for a task like this.  Also, consider paralleling driver stages or maybe even driving the input transducer in bridged mode as if it were a speaker.  Betcha the L'il Gem II would do the job nicely.

Key to getting optimal spring reverb tone is shaping the frequency response of the input signal and the output signal.  Many circuit incorporate some sort of peak limiter to prevent "boinging".

Finally, anything you can do to get the most efficient drive of the input transducer, means you will need less boost in the recovery stage at the other end.  Less recovery gain means less noise introduced.

[d95err]

Copy the reverb circuit out of a solid state amplifier.

Most modern tube amps have solid state reverb circuits as well. For instance, checkout the Fender Blues Jr reverb circuit. It has a current drive reverb circuit where the reverb driver transducer is inside the opamp feedback loop. This is supposed to be better than a traditional opamp reverb driver (e.g. like the Stage Center Reverb).

http://www.schematicheaven.com/fenderamps/blues_jr.pdf

[Gladmarr]

You can also go right to the source http://www.accutronicsreverb.com/schemat.htm 

They have some nice schematics for some simple and more complex reverb circuits based on their tanks. 

The tank you have is similar to a bunch of others I've seen over the years.  The earlier models by that company used to say "made by very pretty girls in Milton, Wisconsin." or something to that effect.  Imagine putting that on your label nowadays!   

[KerryF]

Heres some points answering or responding to some things:
*I have the bottom of the tank labeled with the in and out.
*Someone may be drawing up a tube reverb schematic for me to use today (I will post it).
*My dad and I are about to drill the little things holding the bottom on, off to see inside.
*The resistance of In is 304ohm, and the resistance of Out is 1.5k .

[KerryF]

Ok, well I have pretty much the whole schematic drawn out for this.  All I need is a Op Amp (TL042) boost circuit for the beginning.  Heres how the thing will go:

Input->Op Amp Boost->Reverb Tank->Full 12ax7 Gain Stage->First Half 12ax7 Gain Stage->Fender ToneStack->Second Half 12ax7 Gain Stage->Output

Pretty crazy!  I have named this pedal The Pink Verb after the person who helped me greatly in designing this!

So someone draw me up a little schematic for a boost stage liek the one if the Stage Center Reverb.

Thanks, Kerry.

[KerryF]

Ok so I just plugged this Reverb tank into a little Op Amp gain circuit to drive it.  It works!  But that was only to test to make sure the tank actually works.  Heres a schematic me and someone else (he helped me ALOT with it!) came up with.  Tell me what you think of it:



*Those three 22uF caps coming off the tube Cathodes...  They actually go in parallel with the resistors there.

Tell me what you think please!

[idlechatterbox]

wouldn't mind seeing what the tank looks like on the inside.... unless it's too much hassle to post the jpg