58 lines
3.7 KiB
Plaintext
58 lines
3.7 KiB
Plaintext
|
||
Instructions for building a passive line level mixer capable of mixing
|
||
numerous line outputs down to a single channel. Ideal as a mini-submixer.
|
||
You need a drill, some tools, a soldering iron, and about an hour of free
|
||
time. Parts will cost about $10.00.
|
||
|
||
Passive Line Level Mixer
|
||
|
||
First make a run down to your local Radio Shack and pick up a small metal
|
||
box (aluminum is OK, metal will last longer when pulling jacks in and out
|
||
of the thing all the time though), and some 4.7K ohm 1/2 watt resistors.
|
||
The quantity of resistors you buy depends on how many synths you want to
|
||
mix down to one channel. For two synths you need two resistors, three synths
|
||
needs 3 resistors, etc.etc. You will also need an appropriate number of 1/4"
|
||
mono phone jacks, one for each synth and one for the sum output. If you
|
||
don't already have some lying around, you'll need about six inches of 22ga.
|
||
solid wire. All of this shouldn't cost more than about $12.
|
||
The theory of operation is this...
|
||
You are not really supposed to just "Y" two or more outputs together as
|
||
they can sometimes "talk" to each other which is undesirable. It also
|
||
places a heavier load on both synths due to the impedance changes that
|
||
happen when you connect two outputs together. Most modern day IC output
|
||
amps are current protected so as to not blow out when connected like this,
|
||
but they don't really work quite right in the mean time.
|
||
This circuit is simply a "legal" way of doing this so that no extraneous
|
||
loads will be imposed on the output amps and everything will work just
|
||
the way it's supposed to. Since all synths have output controls of their own,
|
||
you can set individual balances using those.
|
||
You can connect as many synths as you want together using this circuit, with
|
||
little or no gain loss. If your synths utilize stereo outputs and you wish
|
||
to retain stereo, I recommend you build two of these little boxes, one for
|
||
left and one for right and send the sum output from each box into a channel
|
||
in your main mixer so you can pan them accordingly.
|
||
As for the construction, drill and mount the 1/4" jacks into the box
|
||
first keeping in mind a sensible layout such as the inputs on one side and
|
||
the sum output on the other. The wiring is a simple "series resistor in the
|
||
output wire of each synth" method. In other words, take one end of each of
|
||
your resistors, tie them all together and solder them to the hot pin of
|
||
the SUM OUTPUT 1/4" jack. Now the other end of each of those resistors
|
||
connects to the hot lead of an INPUT 1/4" jack ( using a piece of wire if the
|
||
resistor lead won't reach). If you are using a metal or aluminum box you
|
||
really don't need to connect any ground wires to each other because the
|
||
box will ground them together. Make sure you mount the 1/4" jacks WITHOUT
|
||
any insulators as they need to be firmly grounded to the box.
|
||
You are in business!
|
||
Simply connect the output of each synth into an INPUT 1/4" jack and connect
|
||
the sum output to a line input channel on your mixer board.
|
||
If you sit back and look at the wiring now, and follow the flow of any
|
||
one of the INPUT jacks coming from one of your synths, you will see that
|
||
it need only travel through 4.7K ohms of resistance to get to your main mixer
|
||
board input. But it must travel through 9.4K ohms to be able to "talk" to the
|
||
output of another synth. This 9.4K is seen as a pretty "normal" load to the
|
||
output amp and no interaction will occur. Put the cover to the box on now and
|
||
try it out, you will find that since there are no active electronics involved,
|
||
it will be completely noise & distortion free and each synth will sound
|
||
just like it always does. Have fun with it!!
|
||
Curt[75076,3126]
|
||
|