I just finished assembling a SMR4+ for a Tubika kit purchased from TubeOhm. It sounds great and is responsive to the controls, but I can’t seem to get it to self-resonate as per the assembly instructions. I just hear a pop when I play a note, no tone after setting the oscillators to none and filter and resonance to 64. Anyone else come across this and solved it?
Javier, McAllen, TX
A common cause is that one of the 4 filter stages doesn’t work. Check the soldering of the 4 capacitors of the filter core - and check that each of them is correctly placed on the PCB.
Thanks for your help pichenettes!
Problem solved, but it wasn’t the capacitors. I somehow managed to seat the LM13700N without pin 1 going in. Not having the amp bias input will cause some problems. If you hadn’t told me to scrutinize that area I wouldn’t have found it.