My latest module for spring reverb is heavily inspired by the good advice you can find on Rod Elliot, ESP . My own contribution is that I have made it a double module for long and a medium size tanks, with the following extra features for each tank:
- Parallel input from one jack, or two separate inputs, utilizing the switch facility in the jack-sockets.
- Input volume control.
- Local feedback from output to input on the same tank.
- Feedback from one tank output to the other tank input, and vice versa.
- Simple one-potentiometer tone control on each tank.
- Output volume control for each tank. Note that the mixing of inputs and outputs must be done elsewhere.
The sound quality is fine, and it sounds like -well- a spring reverb 🙂 The driver and receiver circuits fits the tanks impedances and frequency responses really well. There is no significant hum, noise or distortion, as long as you adjust input volume while listening to the result. The feedback options are not as useful as I imagined, and oscillation can easily occur on the local feedback. The tone-control is working fine, with flat response in the middle position, bas boost to one side and treble boost to the other side, centered around 440 Hz.
You can see the prototype below:
Please note the nice little green pointers on the potentiometers: These are small pointer-rings that I designed and printed in PETG, and then pressed down around the knobs. I find it a perfect solution to the problem with the orientation and visibility of the position-marker on ALP-potentiometers that I prefer to use. I now use these rings on all my other compact Eurorack modules (and on my KORG Monotron Duo, Monoton Delay and NTS-1).
You can see the diagram of the reverb module here: Dual Reverb v2