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cheap & dirty interface circuit??

K

knowbetter

...basically like henry matchbox...

need to put multiple cd type inputs into several consoles, normally I would use a matchbox, but no budget..

Could wire the whole thing unbalanced, but wondering if anyone had other suggestions.

only going into the consoles!

thanks
 
How 'cheap and dirty' do you want it? Are you experienced enough to roll your own? If not, and you have NO money at all, then go unbalanced. However, if the console is "looking" for a balanced input only, you could build a cheap and dirty interconnect cale. Unbalanced at the CD. In the console, tie center conductor to high side; tie cable shield to low side and ground. Then turn the gain way up. Be aware, however, that you're probably going to get noise. Not the best way to handle this.
 
If you think about the typical interface circuits of most modern consoles, they are pretty similar to the ones found in a matching amp. Consoles have been designed to eliminate the need for matching amps since the 1980s. If you are careful to avoid ground loops, direct unbalanced connections will work just as well as using a matching amp. This will be true of consoles using typical types of active input amps. Some amount of care must be used to avoid loops, though.
 
Have a schematic for an unbalanced to balanced circuit at work. Uses TLO72, 100 K pot, bunch of 10 K resistors, 47 uf caps & 27 pf ceramic. I usually build them on a Radio Shack perf board. Needs a +/- 15 supply--probably about $50 in parts or under depending on your junk box.

-10 in, around +8 out, with respectable distortion noise specs.

Let me know if you want a copy of the schematic.
 
If your console has an active balanced input, then you should be fine with the approach kmagrill suggests. RCA hot to console "hi" and RCA shield to console "lo" input. Use twisted pair cable if you have it. The connection from the "lo" wire to the RCA shield should happen at the CD player end, not the console end. This will give you a much better result than connecting hot to hot and shield to shield. The CMRR performance of the console input helps suppress any noise caused by differences in ground potentials. If you're in a high RF environment, this may not work for you, but most of the time, you won't need the balancing device. Try it.
 
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