Page 1 of 1

Wet/dry circuit

Posted: Wed Nov 24, 2021 9:38 pm
by Fragletrollet

I have a tube opto compressor that I've built that I want to add a wet/dry function to. But I also am building an MTC where I would love to include a Wet/dry function on a couple of the inserts.

I am trying to conceptualize what would be needed. We're combining the pre-processor audio with the processed audio, presumably through a potmeter/switch. Do we add bus resistors to both channels, and a summing amplifier after the wiper of the pot? And either a electronic balanced receiver ala opamps to debalance and buffer the signal, and the same on the other end? Could be discrete opamps and output trafo, or something like that124x/164x chips, or if just buffering and no need for (de)balancing just a unity gain opamp chip on input (summing amp buffers output ?)

Or maybe use something like the JLM Dingo, balanced receiver but then use the THAT VCA to control the volume in opposite directions between the boards with dc from the dual pot, then opamp/trafo driver on the output?

I'm sure you wizards could come up with a simple pcb alĂ  the M/S Mini board that would be very handing not just for your line of Mastering tools, but also for other DIY builds. There is quite alot of interest around the old Send'n'Blend project that unfortunately seems to be dead (although the schematic and self-etch files are available... I've just not come around to start etching on my own yet. Thought I'd skip a step and just learn PCB design... but what a rabbithole :lol: )

Thanks for any input, guidance or ideas :=)

Re: Wet/dry circuit

Posted: Thu Nov 25, 2021 6:18 am
by mediatechnology
Thanks for asking.

You can do it with pots.
A single channel blender can be made with two pots wired contra-rotating with the wipers actively-summed.
As one signal increases the other decreases.

You can also make a poor man's version with a single pot fed at both ends and use the wiper as the output.
It's sort of like a pan control but backwards.

Stereo, done the proper way, requires a 4 gang pot or stepped switch.

I haven't built a board to do this because most MEs want to use a stepped switch (as opposed to VCAs) and the active circuitry to sum them is super-simple.
The heavy lifting, and cost, are the switches.