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 » Mon May 30, 2011 2:07 pm

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
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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 » Mon May 30, 2011 6:51 pm

looks great, love the front panel

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Neutron7
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Post by Neutron7 » Mon May 30, 2011 10:01 pm

that tank sounds really nice. great job!

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Post by mikecameron » Mon May 30, 2011 11:17 pm

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 » Tue May 31, 2011 8:09 am

can't wait to try this out!

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Dego
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Post by Dego » Tue May 31, 2011 8:51 am

Very nice :)

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BugBrand
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Post by BugBrand » Tue May 31, 2011 9:05 am

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 » Tue May 31, 2011 9:55 am

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!


Michael

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Tombola
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Post by Tombola » Tue May 31, 2011 10:21 am

Some notes about the laser panel process here:

viewtopic.php?t=35668

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mig27
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Post by mig27 » Tue May 31, 2011 10:37 am

Thanks, appreciated.
Must look into this closer--

M

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Post by KNYST » Tue May 31, 2011 11:27 am

sound, panel, photos, work, are all: :sb:
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Post by Jarno » Tue May 31, 2011 3:54 pm

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

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Post by fluxmonkey » Tue May 31, 2011 9:12 pm

nice to hear a demo comparison between the 2 springs.
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Post by boothnavy » Tue May 31, 2011 10:49 pm

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?
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Tombola
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Post by Tombola » Wed Jun 01, 2011 2:28 am

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 » Wed Jun 01, 2011 2:35 am

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 » Wed Jun 01, 2011 4:47 am

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 » Wed Jun 01, 2011 10:21 am

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 » Wed Jun 01, 2011 10:25 am

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

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Post by Tombola » Sat Jun 11, 2011 7:07 am

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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Post by timpecter » Sat Jun 11, 2011 8:16 am

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

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Post by cyklopljud » Tue Jun 14, 2011 9:16 am

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 » Tue Jun 14, 2011 12:28 pm

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 » Wed Jun 15, 2011 4:03 am

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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Post by Tombola » Thu Jun 16, 2011 4:33 am

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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