4hp Spring Reverb driver module - schematic, pics, sounds

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Tombola
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4hp Spring Reverb driver module - schematic, pics, sounds

Post by Tombola »

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)

http://soundcloud.com/musicthing/diy-sp ... erb-module

UPDATE: See revised schematic
Attachments
NB - this is a revised schematic correcting a phase problem - use this schematic!
NB - this is a revised schematic correcting a phase problem - use this schematic!
revised spring module.png (22.82 KiB) Viewed 10524 times
board.JPG
board.JPG (86.4 KiB) Viewed 11358 times
springschematic.png
springschematic.png (16.41 KiB) Viewed 11356 times
backlit2.jpg
backlit2.jpg (39.76 KiB) Viewed 11309 times
Last edited by Tombola on Tue Jan 03, 2012 7:04 pm, edited 1 time in total.
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limpmeat
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Post by limpmeat »

looks great, love the front panel
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Neutron7
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Post by Neutron7 »

that tank sounds really nice. great job!
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mikecameron
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Post by mikecameron »

I have been thinking of doing this very thing! Thanks for sharing your work, I'll be building it soon. :yay:
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jimmyambulance
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Post by jimmyambulance »

can't wait to try this out!
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Dego
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Post by Dego »

Very nice :)
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BugBrand
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Post by BugBrand »

Nice work.
And especially thanks for the links to Roy Mallory's interesting articles.
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mig27
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Post by mig27 »

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 :75:

Thanks!


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Tombola
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Post by Tombola »

Some notes about the laser panel process here:

viewtopic.php?t=35668
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mig27
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Post by mig27 »

Thanks, appreciated.
Must look into this closer--

M
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Post by KNYST »

sound, panel, photos, work, are all: :sb:
NOISE HEALS.
patch responsibly.
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Post by Jarno »

Thought you needed something with a bit more oomph to drive a reverb tank. Nice n small this, superb!
:tu:
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fluxmonkey
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Post by fluxmonkey »

nice to hear a demo comparison between the 2 springs.
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Post by boothnavy »

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 - synthesist

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Tombola
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Post by Tombola »

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.
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Tombola
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Post by Tombola »

R9 is another interesting one - it's a kind of damping/stabilising on the recovery circuit - worth experimenting with - or removing - on breadboard
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Tombola
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Post by Tombola »

BugBrand wrote:Nice work.
Very kind - particularly given that you got me started on this in the first place:

http://musicthing.blogspot.com/2008/11/ ... ng-in.html
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Post by 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. :yay:

Image
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Tombola
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Post by Tombola »

Both my tanks are 800 Ohm / 58 Ohm (input impedance / DC). 2575 Ohm / 200 Ohm (output impedance / DC).
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Tombola
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Post by Tombola »

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... )

http://soundcloud.com/musicthing/maths- ... llator-diy
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timpecter
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Post by timpecter »

That is a great demo, Tombola! I'm experimenting with spring reverb now and it's inspiring to hear.
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cyklopljud
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Post by cyklopljud »

Yes yes maybe I'm a lazy DIY'er, but.... any chance of a vero layout of this anywhere..... :help:
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Tombola
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Post by Tombola »

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!
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Post by Jarno »

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 ;-)
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Tombola
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Post by Tombola »

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! :doh:
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