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4hp Spring Reverb driver module - schematic, pics, sounds
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3 ... 10, 11, 12  Next [all]
Author 4hp Spring Reverb driver module - schematic, pics, sounds
I was just about to buy an A199 spring reverb when I decided to save 4hp of space and build my own.

The circuit is based on Roy Mallory's tech note and tone control, which is useful - a symmetrical cut/boost of bass and treble. The drive, recovery, tone and blend buffer take the four amps in a TL074.

The gain on the drive circuit is reduced quite a bit - R10 is 660R rather than 62R (it's R1 in Mallory's article), and the recovery circuit has a variable drive.

I put a couple of phono jacks on the back of my Doepfer case, so it's easy to plug in an external tank - a nice rich 6-spring 9EB2C1B (mainly because I built the circuit with the 8EB2C1B from a fender amp)


UPDATE: See revised schematic
looks great, love the front panel
that tank sounds really nice. great job!
I have been thinking of doing this very thing! Thanks for sharing your work, I'll be building it soon. applause
can't wait to try this out!
Very nice smile
Nice work.
And especially thanks for the links to Roy Mallory's interesting articles.
Nice one!

And I also dig the plexi front plate.
Looks a bit like my OSC303.

Care to share how you built these?
I'm currently looking cheaper front plate alternatives than the usual Schaeffer job


Some notes about the laser panel process here:
Thanks, appreciated.
Must look into this closer--

sound, panel, photos, work, are all: SlayerBadger!
Thought you needed something with a bit more oomph to drive a reverb tank. Nice n small this, superb!
thumbs up
nice to hear a demo comparison between the 2 springs.
If you made R10 in your circuit variable with a pot, could you then control the input amount?

Also, would any modification be necessary if using 15v?
Boothnavy: I did try that on the breadboard with a 1k pot, because I assumed I'd build it with variable drive and fixed recovery. It didn't work well for me - very limited useful range, quick to distort in a nasty way, but then I didn't test it with a huge range of input signals.

Re: 15v - sorry, I have no idea - I guess the TL074 datasheet would give you the max voltage. The other values don't seem that critical so you'll probably be fine.
R9 is another interesting one - it's a kind of damping/stabilising on the recovery circuit - worth experimenting with - or removing - on breadboard
BugBrand wrote:
Nice work.

Very kind - particularly given that you got me started on this in the first place: ding-in.html
Glitch Militia
What input / output impedance is this designed for ? I do not know that tank that you got.

I currently got this one on breadboard, tweaking some values etc. I like the sound of yours, so I'll try that next. applause

Both my tanks are 800 Ohm / 58 Ohm (input impedance / DC). 2575 Ohm / 200 Ohm (output impedance / DC).
This shows off the sound of the big six spring tank quite well. (

Disappointingly, the six springs are actually mounted as three springs with joints between the separate springs... )

That is a great demo, Tombola! I'm experimenting with spring reverb now and it's inspiring to hear.
Yes yes maybe I'm a lazy DIY'er, but.... any chance of a vero layout of this anywhere..... help
Sorry, as you can see from the pic, I laid it out in a rather freestyle/chaotic way on pad-per-hole perfboad with lots of kynar wire... Would be a tiny board if you did it properly!
I consider myself to be lazy as well, and I think duplicating a vero or perf layout is just too much effort, I always make it up as I go. So much easier when you just have to look at the schematic instead of also looking at the layout as well, of course a pcb is even easier still ;-)
I always build first on breadboard, to get the thing working and get confidence that all the components are right and that I 'know' the circuit - I don't think I've ever successfully built a circuit by following a vero layout - I'm not precise/patient enough. I have a shelf full of non-working stompbox circuits built like that! d'oh!
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