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DIY Stompboxes => Building your own stompbox => Topic started by: snufkin on September 20, 2011, 04:06:25 PM

Title: Salvaged Spring Reverb Tank Help
Post by: snufkin on September 20, 2011, 04:06:25 PM
Hi guys I just got a small cheap tank out of a dead amp and would love to make a reverb however it's input/output impedance is labelled at 600-2.2k

any one have any advice on circuits for the reverb drivers, the simpler the better
how do I make the the correct impedance?

also as I want to house it in my modular synth case 12v power would be a benefit

thanks

Chris
Title: Re: Salvaged Spring Reverb Tank Help
Post by: artifus on September 20, 2011, 04:42:46 PM
http://www.diystompboxes.com/smfforum/index.php?action=search2 (http://www.diystompboxes.com/smfforum/index.php?action=search2)

here's my recent super lofi effort, thrown together with parts i had laying around rather than designed as such, hence the strange layout and components - masses of room for improvement - but may give you some ideas. i'm using it to drive a mini dc motor salvaged from an old mobile phone with a piezo disc pickup. no actual reverb tank to try it with, just homemade stuff but it works well enough for me.

(https://lh5.googleusercontent.com/-WKanPAcQ6dI/Tnj2kF7g3jI/AAAAAAAAAQ4/UnYDqPK4cX4/s640/lofireverb.jpg)
Title: Re: Salvaged Spring Reverb Tank Help
Post by: snufkin on September 22, 2011, 05:20:51 PM
thanks man inspiring stuff!  :D


how does one modify a reverb driving circuit's impedance ?
Title: Re: Salvaged Spring Reverb Tank Help
Post by: artifus on September 22, 2011, 05:40:40 PM
as one would any other piece of audio equipment - to what ends? what is your input? what is your output? these were not issues for me in the above build as it was an anything goes, whatever works scenario - hi-fi was not an issue, effect was.
Title: Re: Salvaged Spring Reverb Tank Help
Post by: snufkin on September 22, 2011, 06:09:44 PM
well my tank 600-2.2k  so I guess I need to put together a driver with matching 600 impedance and a recovery amp with 2.2k impedance

have I got that right?
Title: Re: Salvaged Spring Reverb Tank Help
Post by: artifus on September 22, 2011, 06:17:10 PM
it will only effect level and frequency response which will only be an issue depending on your tastes ie - it will sound different and not as intended. if hearing it as intended is important to you then go for it. lots of info on impedance if you search for it. it will 'sound' regardless.
Title: Re: Salvaged Spring Reverb Tank Help
Post by: snufkin on September 23, 2011, 06:14:56 AM
so just throing together some simple pre-amps circuits of any impedance wont burn out the coils in the spring driver ?
Title: Re: Salvaged Spring Reverb Tank Help
Post by: petemoore on September 23, 2011, 07:20:27 AM
 "Transducer = Microphone, Speaker, and reverb transducers, generally it's heat that burns out the transducer, though it is still possible to 'pop' one with a peak.
  The transducer that drives the spring to vibrate needs to have an amplifier that can control the motor 'well', or to where it 'works'. Better' is an impedance matched amplifier with enough headroom to 'accomodate'. An impedance mismatch might and does 'work', however frequency response, lack of drive-ability, or distortion may result. The words "Well', 'works' and 'better' tend to get more clearly defined when 'it works' is compared to 'it works better' [or worse].
   So the spring wiggles when the amp drives the transducer, now to the other end of it...
   Plug that into an input = reverb/source, 100% spring-sound.
   Mix the spring-sound with the dry input and call it a 'reverb' amount knob.
   Drive the spring harder and call that a 'dwell' knob.
   The Stage Center Reverb shows a basic circuit that shows the drive, tank-output signal gain recovery and mix circuits needed for a basic reverb.
   The LM386 wires up quickly as anything 'amplifier', and can drive some reverb tanks, the real limit is the 15v supply, fine for less than super-boosted signals, may distort when fed 'hot' signals.
   Digital is now mentioned as an affordable option, a tube reverb is a lot of trouble to put together and one I made sounds very 'fender tube-reverb unit' sound to it.
Title: Re: Salvaged Spring Reverb Tank Help
Post by: jefe on September 23, 2011, 07:46:59 AM
Quote from: snufkin on September 20, 2011, 04:06:25 PM
Hi guys I just got a small cheap tank out of a dead amp and would love to make a reverb however it's input/output impedance is labelled at 600-2.2k

any one have any advice on circuits for the reverb drivers, the simpler the better
how do I make the the correct impedance?

I'm not sure if this helps, but check out the Stage Center Reverb project at General Guitar Gadgets:

http://www.generalguitargadgets.com/projects/25-reverb/43-stage-center-reverb (http://www.generalguitargadgets.com/projects/25-reverb/43-stage-center-reverb)

At the very least, perhaps this can give you some ideas.