[sci.electronics] Need Audio Mixer

jantypas@hope.UUCP (John Antypas) (03/22/88)

A question for the net experts in this sort of thing?  We find
ourselves in need a mixer for audio recording.  Nothing fancy, but
nothing standard either.  We could go to a certain retail electronics
store and pay their "You can't go anywhere else" prices, but why?
Therefore, I (not an engineer) am writing to the experts for their
wisdom on this subject.

I may be wrong, but I figure that a 6 in/2 out (3 stereo/1 out) mixer
can't be that difficult (in theory) to build.  Is it?  What would we
need in terms of basic parts?  (Obviously we would need 6 pots, 14 .25" jacks),
What about the problem of signal degradation?  How do we overcome the problem
of squeezing six inputs into two?  

Now let's get fancy.  What would it take to add reverb?  Is this even
feasable? 

If anyone has any answers/schematics they'd like to provide, we'd be 
very grateful.

Many thanks.

John Antypas
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daveb@llama.rtech.UUCP (Crack? No thanks, I've got a new CD player) (03/24/88)

In article <163@ucrmath.UUCP> jantypas@hope.UUCP (John Antypas) writes:
>A question for the net experts in this sort of thing?  We find
>ourselves in need a mixer for audio recording.  Nothing fancy, but
>nothing standard either.  We could go to a certain retail electronics
>store and pay their "You can't go anywhere else" prices, but why?
>Therefore, I (not an engineer) am writing to the experts for their
>wisdom on this subject.
>
>I may be wrong, but I figure that a 6 in/2 out (3 stereo/1 out) mixer
>can't be that difficult (in theory) to build.  Is it?  What would we
>need in terms of basic parts?  (Obviously we would need 6 pots, 14 .25" jacks),
>What about the problem of signal degradation?  How do we overcome the problem
>of squeezing six inputs into two?  
>
>Now let's get fancy.  What would it take to add reverb?  Is this even
>feasable? 
>
>If anyone has any answers/schematics they'd like to provide, we'd be 
>very grateful.

Just about every circuit you could want is somewhere in Walt Jung's "IC
Op Amp Cookbook", though you probably wouldn't want to use 741's or 301's
any more.

Before you proceed, however, I'm forced to question your sanity. 
Building a mixer may be interesting, but it is almost never
cost-effective.  What are you going to be using it for?  What are your
quality, reliability, and durability requirements?  What do you need
that isn't available in a standard board?  6x2 isn't very complicated.  

You'd have a hard time building one from decent quality parts for < $100
and 20 hours of your time. I suggest you paw through some musician's
classified ads and get up a  board from some band that is going bust. 
You should be able to find something for $200-$400 pretty easily.  

Reverb is best done with an add-on box, preferably a digital or CCD
device.  ALmost any mixer you would buy comes with a reverb/effects send
on each channel and a master return into the main busses.  I have a sick
fondness for ancient tape echos (Echoplex(tm) and the Roland Space Echo
201/301), but they are thoroughly obsolete.  Springs are very nearly
worthless except in some very unusual circumstances calling for special
effects.  In particular, don't be tempted to buy a $14.95 raw spring and
put your own driver electronics together.  It just isn't worth the
trouble.

(why do you think my initials are written this way?)

-dB
"Do you programmers do sh*t like this a lot?"   "Every g*d*mn day."
{amdahl, cpsc6a, mtxinu, ptsfa, sun, hoptoad}!rtech!daveb daveb@rtech.uucp