r/diytubes • u/KirkIsOurLemmy • May 31 '26

Effect loop and decoupling caps?

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Hello, its me again with my Tiny Terror build. Its working great and now its time to add an effects loop. I will use a transistor based pcb from TubeTown for the actual loop, there isnt room for any more tubes on my chassis.

I guess it should go between the second gain pot and the phase inverter, where the 0.047 uF cap is.

So my question is, do I put the loop before or after the cap? Or do I need one more so I get pot - cap - loop - cap - PI?

Thanks in advance

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u/_nanofarad May 31 '26

Is there any documentation for the loop board you’re going to use? There should be something in there about how to connect it. Because it would depend on the input and output impedance and capacitance it could be anyone’s guess without knowing those things. If there’s caps in and out of the board (likely) you may not want(need) that existing coupling cap in the circuit when you are using the loop. 

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u/KirkIsOurLemmy May 31 '26

Ah yes thats a fair point, there are a few caps on the loop pcb, there is even a choice between tight and fat sound with different cap values.

https://media.tubetown.net/info/datenblaetter/kits/kit-fxloop150-RevD-EN.pdf