Hi,
I recently got my first synth and im triyng to do some experimental stuff.

I would like to build a fully DIY Spring Reverb (preferably stereo) and i have some ideas but don't really understand much of the eletronics (even though all the videos i've seen and stuff i read )so if someone could help it would be great.

This is basically my idea(Image Attached).

My main doubts are:
-What amps should i use and speakers (or if i sloud evan use speakers to drive the springs)
-Is the Dry/Wet / Mix knob possible and if it is how could i do it.
-What Potentiometers/Hardwere should i get.


Thank U.

Hi, have a look here: https://sound-au.com/articles/reverb.htm
You need to build a device with a tank driver, a recovery amp and a mixer (a peak meter and a compressor/limiter are also nice to have but they are not required).

That article will show you the basic schematics and will help you to chose the right one depending on the specs of the reverb tank you choose.

If you want to add a feedback loop, you can just take the output of the output mixer and connect it through a potentiometer to the summing point of the input stage. I built a spring driver box a few years ago based on those schematics and I added the feedback loop, but the feedback loop is not that useful in practice: if you use it by itself it will sound just as a larsen, so I added an insertion point on the feeback path (so I can insert something like a delay)... still, the feedback gets really little love.


In practice, there are some eurorack kits to drive reverb tanks, maybe even some dedicated devices (I think there's one by Radial, in 500 format)... you may be able to find something off the shelf or at least find a kit to build... Still, that article will explain a few useful things.

having a look at that article now.
i was assuming something like the OP diagram, where you have one amplifier stage at input, and another on the output.

thing is, i don't really understand impedance. there, i've said it. i mean, vaguely, yes, general idea: i'm familiar with Line, Mic, Guitar, Phono, balanced/unbalanced, but that's about as far as it goes; i don't use any DI box, i do have a couple of mic pre-amps that i never use (because i'm not using mics), and do have a mixer with aux send.

and i now have a new reverb tank from aliexpress, with RCA input and output, and inductors at either end of the spring.

so i measure the resistance across the inductor to obtain its impedance? impedance:
https://en.wikipedia.org/wiki/Electrical_impedance

"In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit.[1]"

reactance being: "the opposition presented to alternating current by inductance and capacitance.[1]"

plenty of scope for going off on a tangent :-)
trying to keep this simple.

and do i need to know the impedance at both ends of the spring, or can i just wing it adjusting Gain at input and ouput?

in the graphic above there's a speaker at the input to the spring, and microphone on the receiving side. makes sense: could put a speaker and microphone in a bathroom in a send/return loop. so the speaker needs to be 'driven', and the microphone signal needs a pre-amp.

from what i read, i should be able to go straight out of a mix aux send into the reverb tank, and bring it back in to a mono channel using the input gain?
how am i doing with impedances there?

can you damage a device by using mismatched impedances? say if you tried to audition a line output plugging in headphones? (asking because i might have damaged something once doing this, not sure.. but this is making me slightly tentative before proceeding.)

say if i get a headphone amplifier for the input, and use a mic preamp like behringer mic100 to restore level? could i use another mic preamp on the input instead of the headphone amplifier? not the same thing though, is it? or is it just a matter of amount of gain at either stage?

ideally i'd quite like to build it as a selfcontained unit, with 2 channels. would a 4x channel headphone ampilifier be able to deal with 2 inputs? (how would they be separate?)

in a video i saw today, the guy uses a DI box on the output, into a decent pre-amp (lost the link atm). so he's blasting the signal into the spring at a decent level (Headphone hotter than Line?), then making the output signal balanced with the DI box before boosting it with the pre-amp.

how about getting a couple of cheap chinese stereo preamp circuits?

I've built a few DIY spring reverb ckts along the way. IMHO, the very best way to go is to drive the springs in the feedback loop. This drives the spring so the recovery amp does not need de-emphasis. If you are building from scratch, let me know and I'll see if I can dig up the schematic. I believe it's the same or similar to Craig Anderton's "Hot Springs"

...

don't know yet: i have a brand new aliexpress reverb tank that looks ok. was thinking of ordering a 2nd unit and some cheap pre-amp boards.

i'm still at reading-up stage. read all of the AccuBell site and downloaded their schematics.

here's the spec' of the tank i bought:

Input
Impedance: 600 Ohm
Inductance: 23.0 MH ±10%
DC Resistance: 28.0 Ohms ±10%
Recommended AC Drive: 3.1 MA For Approx. 3.5 AT
Output
Impedance: 2250 Ohm
Inductance: 330.0 MH ±10%
DC Resistance: 220.0 Ohms ±10%
Decay Time: Medium 1.75 ~ 3.0 SEC
Connectors: Input Insulated, Output Grounded
Locking device: No Lock
Mounting Plane: Horizontal Open Side Down

and now i'm reading this discussion, having done a quick search on "600 Ohm":
https://forum.allaboutcircuits.com/t...edance.178682/

here's the video i was watching yesterday (skip past the channel bluurb)

what about input and output filtering?
i see a low cut on input on one schematic. i thought it was on the output before the recovery pre-amp? or both?