Simple 2 chnl line level xlr to xlr combiner

[Brent]

After a bit more research, it looks like what I really need is a simple summing box?

I found a schematic for a passive 8 channel summing box here:
http://www.forsselltech.com/8chsum_2.pdf

However I would need 3 channels at most, so I'm not sure how that affects the chosen resistor values if I modify the drawing? Does anyone know what the ideal values for these would be?

Ideally I'll be summing the outputs of a Buzz Elixir, LaChapell 583s, and an Avedis MA5. The summed output will then be fed into a buzz Essence ( or tonic) both of which have 20k ohm input impedances.

[tINY]

What exactly are you trying to do? do you need balance control? And how many inputs are you using?

An active design will allow for a big difference in output between impedances.



-tINY

[morebutter]

brent averill makes one, uses xformers

Brent Averill Enterprises | Products

[Brent]

Originally Posted by tINY

What exactly are you trying to do? do you need balance control? And how many inputs are you using?

An active design will allow for a big difference in output between impedances.


-tINY

It's really for my live acoustic guitar setup. I have 2 pickups and a mic in my guitar which I would have blend control on the preamps themselves. I just want to sum these into a mono signal so I can then feed into the rest of my 500 series EQ's comps etc as needed. No balance control or anything needed.

Originally Posted by morebutter

brent averill makes one, uses xformers

Brent Averill Enterprises | Products

That's definitely close given my opening post headline, but I'd rather not dish out 500 bucks just to get a mono signal if I can build something simple (maybe I can't?). At that price I could buy a 1U whirlwind line mixer or something.

[Tim Farrant]

Yes, the circuit as drawn will work. The resistors can be 3k3 ohms, there will be some loss thru it of course.

Tim

[huub]

But you can always try just using a Ysplitter, depending on impedance it might sound fine.

[jitterybit]

Whirlwind IMCOML IMP
$120

[CompEq]

I'm doing a similar project. If I wanted to modify the schematic in Post#2 to add an identical summed output, is any additional circuitry necessary? Ie: would I need to add resistors between each pair of Pin2 Outs and between each pair of Pin3 Outs?