GPCB ParaMix

mbenbranch

Active member
Just wrapped this GPCB ParaMix up today. Built for my brother to use in his bass and electric cello pedalboard. He was looking for a way blend in his heavily effected sounds but retain the fundamental bass and transient. This circuit fits the bill and can do a few more cool signal routing tricks.

Build docs list 200 nF caps for guitar with recommendation to increase for bass use. I used 680 nF to let plenty of low end through. Tayda Metallic Champagne Gold enclosure because as a teenager I used to drive a Volvo station wagon in the same color and we used to drive around listening to all kinds of obnoxious music.

Pretty easy build, required specific always closed mono jacks for the insert loop. I used a bi-color LED, first 2 I tried were duds finally got it lit up with the third. I need to either remember to test those before I solder or not buy the cheapest ones I see on Amazon. Maybe both.
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I have a couple of these on my bench right now!
Me too! Still trying to figure out how to use them. I'm thinking of using it in a sort of "improved buffered loop" pedal I built that would let me blend my reverb and delay settings globally as opposed to managing the "mix" on each pedal. I'm sure there's a way to do it. Just haven't gotten around to it yet.
 
Nice build and cool that it works for you! But honestly, some of the design decisions in this circuit are simply mind bogglingly stupid.
 
Nice build and cool that it works for you! But honestly, some of the design decisions in this circuit are simply mind bogglingly stupid.
I haven't really looked too closely at the build yet, can you elaborate? (Just in total transparency, there's a lot of GPCB boards and common layout decisions I find confusing and not very intuitive). I generally don't look forward to building those projects, but it sounds like a useful utility board from the description.
 
I mean there isn't anything that would make it non-functional, but generally speaking:
  • No protection and offboard mounted pots (Personal gripes)
  • the 2nd loop it has is strictly in series with the dry signal, which has its uses but it's a bit redundant and not very well explained in the manual. The guy I built it for back then thought it would be 2 parallel loops.
  • Series loop doesn't have a disengage switch, which could have been more useful than putting a kill switch on the input of the parallel one.
  • Speaking of the kill switch, manual says it's in favour of keeping trails on delays and reverbs, but that could have also been achieved by adding a buffered bypass option or else.
  • Mix knob on the actual parallel loop only acts as a volume control on the loop (which is fair enough but considering there's no real gain makeup afterwards, it's not ideal)
  • There is a gain stage in series with the dry signal for no reason, especially since the dry level pot turns it down anyway. Both the gain and the volume are located before the series loop input too because reasons.
  • There's no boost or master volume either, which would have been more useful than the gain stage on the dry signal.

I also had some experience on their support forums when I had troubles with one of their projects that leads me to think the owner's electronics/pedals knowledge isn't that great in general.
 
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Thanks for the explanation, hmmmm....makes me rethink using this, I also thought it was two independent loops.
I just looked through the build doc and I'm still confused as to what it's actually doing (hahaha).

I think I may just wind up doing an old school wired job with a couple of buffer boards like my last one.
I really wanted it for the blend control though.
 
Thanks for the explanation, hmmmm....makes me rethink using this, I also thought it was two independent loops.
I just looked through the build doc and I'm still confused as to what it's actually doing (hahaha).

I think I may just wind up doing an old school wired job with a couple of buffer boards like my last one.
I really wanted it for the blend control though.
If you want a simple buffered blend, check out the runoffgroove splitter blender or the classic buff'n'blend/split'n'blend. If you want a an option to buy, there is also the OBNE Blender that has 2 loops and if you want lot of control and even 3 loops, look for the EHX Tri Parallel Mixer.

Maybe it's time to put a proper blend pedal on the wishlist.
 
If you want a simple buffered blend, check out the runoffgroove splitter blender or the classic buff'n'blend/split'n'blend. If you want a an option to buy, there is also the OBNE Blender that has 2 loops and if you want lot of control and even 3 loops, look for the EHX Tri Parallel Mixer.

Maybe it's time to put a proper blend pedal on the wishlist.
Well I think the PPCB Dual Loop board might be a good place to start.
Actually @Robert IS working on a proper blender, I have one of the protpotypes but waiting for him to finish tweaking the values on them.

Ideally what I want is the EQD Swiss Things. That seems perfect to me. But I want it DIY of course.....:)
 
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