[sdiy] Final-stage mixer module?

[Harry Bissell]

If you want to block DC and you don't know if the inputs have a DC bias, then use a capacitor
on each input. The other advantage of this is that the input impedances are usually higher than the output, so smaller value capacitors
can be used for the same frequency response.

If you will patch in and out of these points live, include a high value resistor (1 MEG) from the input side of the cap to ground. This
will keep the capacitor from developing a charge (POP!) when you plug something into a previously floating input.  (switching the input jack to ground
when there is no connection can do the same thing).

You may also use a non-polar electrolytic on the output, to prevent any residual DC bias from entering or leaving the circuit at that point.

H^) harry

----- Original Message -----
From: Mark Rivera <marr at lumin.us>
To: Synth DIY <synth-diy at dropmix.xs4all.nl>
Sent: Fri, 09 Mar 2012 13:51:53 -0500 (EST)
Subject: [sdiy] Final-stage mixer module?

I'd like to make a simple (TL07x) mixer for the final output of my
modular. I want it to block DC. I recall seeing a schematic that
showed two electrolytics back-to-back to achieve this. Is it as simple
as that? Or is it better to have small ceramics on each input instead?
Both?

Mark
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-- 
Harry Bissell & Nora Abdullah 4eva