Issue with isms Reverb

Hi, this is my first post in this forum, forgive me if I am not following the rules for a first post. Anyway, I am super excited to have dived into Monome, Grids, isms, Triology realms. And I just hit the order button for Ansible and Arc 2.

However, I bought the isms second hand and I have an issue I cannot understand (and I am no techy, I make music for fun). I hooked up the supplied reverb tank and then a second one I had. I also tried several RCA cables, in the end everything was the same. I only got crackling and noise from the reverb. I tried without an input signal, just with the tank hooked up and controls fully wet and hitting the springs. Just very very very faintly I could distinguish the spring sound behind all the noise. With an input signal on dry, the dry signal is perfect and the more I increase to wet, the worse the sound gets.

What else can I try?`
Thanks for helping me out.


Hi Alexander. Welcome!

I only want to ask this since you didn’t clearly state that you have tried it: are you sure that you have plugged your input and output in correctly with the RCA cables? If you haven’t, try switching the input and output plugs into the isms.

Otherwise, it could have to do with impedance specs of the reverb tank. Is the tank you have from the previous owner the one that came with the isms?

I’m the original owner. I did test the reverb before sending it away. I hope that there is some kind of mistake in patching. Have you tried to connect it like in This video tutorial?

@Drewsky It’s the original included spring tank.


@ Barksten: yes, as also mentioned by separate mail, I have connected it as shown in the video. And I have two more spring modules in my modular system, so I have a bit of an idea what could go wrong at this stage.

@ Drewsky: thanks for the comments. And as also mentioned by Barksten: yes to both questions, it is connected correctly and it is the original tank.

Anything else I could try out?

Best regards and thanks for everyone’s kind help.

did this unit get sent in to have a circuit modification made to improve the noise floor on some sections?


I really don’t know as I purchased it second hand from @ Barksten.

I was not aware that such modification might have been necessary. Would I have a possibility to find out if on my rack this was necessary (serial number for example) and if yes, was it performed.

@ Barksten: do you know by any chance of this?

Thanks again for coming with ideas, I am sure this can be sorted out in due time.


No. It’s all original, no modifications.

cool, no big deal. e-mail and we’ll get it sorted.

Ok, thanks, will do!