DIY spring reverb driver?

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joninc
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DIY spring reverb driver?

Post by joninc » Wed May 10, 2017 4:29 pm

I love the spring that's built into my Hammond A-100 so I bought another necklace spring off Ebay and am trying to figure out a way to drive it and use it as an outboard spring reverb unit.

I know about the Radial Tank Driver 500 series module and I may resort to that but I wanted to see if there were any better DIY options - preferably tube.

From what I understand it's input inpedance is like 1.4 k ohms. My tech says it needs to drive 4 volt ac into 1.5 ohm load

Any tips?
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Post by Matt C. » Thu May 11, 2017 4:19 am

http://sound.whsites.net/articles/reverb.htm

not tube, but I built a couple of these circuits recently and they work well. I think you'll want "Figure 6 - Basic Discrete Drive Circuit For High Impedance Coil". There's also a recovery amp schematic to boost the level coming out of the tank.

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Post by jimjazzdad » Thu May 11, 2017 4:55 am

Rod Elliot's stuff is excellent. I haven't tried his reverb circuits but his web site is well worth visiting: http://sound.whsites.net/index2.html
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Post by I'm Painting Again » Tue May 23, 2017 3:27 am

copy the pioneer sr 101 or fisher space-x-pander circuit

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Post by Scodiddly » Wed May 24, 2017 4:19 pm

Latest issue of TapeOp has a DIY spring reverb article, complete with schematics!

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Re: DIY spring reverb driver?

Post by joninc » Wed Sep 20, 2017 7:30 pm

update:

My tech could not get Necklace #1 to work. I bought a radial tank driver. Still wouldn't pass any signal.

Bought Necklace #2 off ebay. I can plug into tank driver and if i knock the spring i can hear the "doiinnng" but still can't seem to
send any signal through it (using an aux send off board to tank driver and then the send and return on the front of tank driver to said necklace reverb). Actually, with the gain 100% and the drive engaged i can hear a VERY faint whisper of a signal coming through.

So - this necklace reverb seems to be at least partially working (the output).

How can i make this work??? I don't even know where to start... is it an impedance mismatch? The tank driver is supposed to send 1.5K Ohms - i thought that was sufficient for these springs - but i could be wrong.

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Re: DIY spring reverb driver?

Post by Scodiddly » Thu Sep 21, 2017 7:18 pm

I'd probably start by temporarily hooking up each side (one at a time) to a mic input just to see what happens when you touch the springs. That would at least tell you one or both sides isn't totally borked.

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Re: DIY spring reverb driver?

Post by joninc » Mon Sep 25, 2017 10:54 am

Scodiddly wrote:
Thu Sep 21, 2017 7:18 pm
I'd probably start by temporarily hooking up each side (one at a time) to a mic input just to see what happens when you touch the springs. That would at least tell you one or both sides isn't totally borked.
yes - output seems ok but input isn't working.

see previous post:
"I can plug into tank driver and if i knock the spring i can hear the "doiinnng" but still can't seem to send any signal through it "
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Re: DIY spring reverb driver?

Post by joninc » Mon Sep 25, 2017 11:24 am

Doing a little more homework and it appears that the Hammond amp that is usually paired with this spring (AO-35) is a 12W amp driving
an 8 ohm, 8" speaker.

This Radial Tank Driver that I bought sends out 1.5k ohms...

Does this constitute an impedance mismatch?
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Re: DIY spring reverb driver?

Post by Drone » Mon Sep 25, 2017 12:19 pm

How is it wired, is the tank in parallel with the speaker, or in series, or has another amp of it's own?

I mean if it's just in parallel with the speaker, you'd think the amp is designed for the speaker and the tank is considered insignificant in this case.
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Re: DIY spring reverb driver?

Post by joninc » Mon Sep 25, 2017 12:48 pm

There is no speaker in my configuration.

I am trying to use this spring as a stand alone reverb fx unit and use the the Tank Driver as the amp in this scenario.
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Re: DIY spring reverb driver?

Post by markjazzbassist » Mon Sep 25, 2017 12:52 pm

why not email radial? they have diagrams and user guides on their website. if it's not working maybe contact them and see if they can help.

http://www.radialeng.com/pdfs/TankDriver-UserGuide.pdf

have you looked at the user guide yet?

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Re: DIY spring reverb driver?

Post by joninc » Mon Sep 25, 2017 1:24 pm

yes, left a voice mail there already.

I am curious if this looks like an impedance problem - this is above my pay grade
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Re: DIY spring reverb driver?

Post by Drone » Mon Sep 25, 2017 1:52 pm

Yeah, there's no speaker in your application, but the original amp was designed to have a speaker, and it looks like the reverb is across the speaker with a reduction circuit and a lamp protection.

Basically you could recreate the whole amp, with an 8 ohm speaker load and the etc. -or- you could figure out how you want to drive just the reverb circuit.

Image

Also looks like there are two input coils, do you have both of them hooked up? Or are there two tanks on the original thing?
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Re: DIY spring reverb driver?

Post by joninc » Mon Sep 25, 2017 2:13 pm

sorry if this is hard to follow. I'll attempt to clarify:

I don't have the AO-35 Hammond amp.

I am attempting to drive the necklace spring (different from a typical amp tank)
with the radial tank driver (http://www.radialeng.com/tankdriver-specs.php)

It's designed to work with "most" springs. But i am starting to think that this one is the exception...
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