combining 2 or more audio signals?

[r-wu]

I am running out of mixer inputs and I would like to build a merge box to make subgroups. E.g.: I would put all my fx's on 1 stereo input.
The stereo merge box needs no level control and no other goodies.
just 2 (or more) inputs -> 1 output

Is this possible without reducing the soundquality?
I found this site. http://www.hut.fi/Misc/Electronics/c...linemixer.html
Below the page there is a simple design with 10k resistors. Any thoughts on that?

thank you

[sorry if this is in wrong forum]

[mrfeedback]

As the text says the attenuation is high, but this may not be a problem in your application.
Better is an active summing stage as this simple mixer .

Eric.

[r-wu]

i dont like the idea; because thats a small mixer.
to much work for a temporary solution.
I don't want/need volume or tone control, just a line sum

There must be a simple way to do this?
I've found this site , where there is a simple circuit using 10k resistors.
The major drawback is a 6dB attenuation.. Also the output impedance is quite low, but that should'n cause a problem.

Other suggestion?

[pinkmouse]

Originally posted by r-wu
i dont like the idea; because thats a small mixer.
to much work for a temporary solution.
I don't want/need volume or tone control, just a line sum

r-wu

Any passive solution will involve attenuation at some point, that is the laws of nature. If you find you run FX returns at a low level, then a passive mixer might work, as long as you have extra gain available on the desk inputs. But you will ruin your gain structure and increase noise with this solution.


I would just build the active one as per Eric's (mrfeedback), suggestion. Parts will cost very little, you could make it up in about half an hour and run it from batteries or a wall wart. You may think you just want it for one occasion, but once it's in your toolbox you will find a whole host of uses for it, believe me, i've been there

[r-wu]

I will have to follow Eric's advice then..

Dont get me wrong, this doesn't have to be passive. I just want a clean sound, and I think I can achieve that by using as little useless controls as possible. (i really dont need the volume and tone pots)

Anyway, thanks for the advice.
If anyone has other suggestions, I haven't started building yet! ;-)

[Helix]

Originally posted by r-wu
I will have to follow Eric's advice then..

Dont get me wrong, this doesn't have to be passive. I just want a clean sound, and I think I can achieve that by using as little useless controls as possible. (i really dont need the volume and tone pots)

Anyway, thanks for the advice.
If anyone has other suggestions, I haven't started building yet! ;-)

Just ditch the volume pot and 15K res then, but keep C*06 and R*16.

Please be aware that this is Rod Elliott (ESP) design.

[moamps]

Originally posted by r-wu

If anyone has other suggestions, I haven't started building yet! ;-)

Hi,
what you think about passive summing with transformers; no attenuation, good isolation, ballanced inputs and outputs..not cheap but..
http://www.jensen-transformers.com/as/as080.pdf

Regards