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3 or 4 out signal splitter

:

10/28/1999 10:37 PM

3 or 4 out signal splitter

Looking for suggestions or possibly mods to existing designs for a splitter that would allow me to run several effects loops to 3 or possibly 4 dedicated outputs.

I plan to use a system of a/b switch boxes for several preset sounds that in turn go to various time based effects.

splitter (***)
stereo outs (==)
mono (--)

|dist |--|dly|=======| *** |----amp 1
|od |--|dly|======= | *** |---amp 2
|clean|--|dly|chrs|===| *** |----amp 3

In this settup, amp 2 is dedicated for wet signal coming off of the delays and chorus and amps 1 and 3 are for dry signals for the 3 presets (clean / OD / dist).

Could something like this be done with a simple diy junction box, or would it require some sort of buffer and/or isolation circuitry to avoid ground loops and signal loss?

I thought about trying to do this with some sort of miniature mixer but that seemed like overkill. Appreciate any input.

Thanks,

pHiL

10/29/1999 1:15 PM

Good idea, and good insight into some of the problems.

In any setup with as many wires running around as this, death by hum is always lurking. You'll probably need to isolate the three amps somehow. There is a suitable isolator schematic at <http://www.geofex.com>GEO that will transformer isolate the signals. If the amps are all three wire and all plugged into the same local outlets (gets the ground wires to be common) you might be able to do it with a differential amplifier opamp isolator. I have that one around somewhere, it was suggested by someone here at ampage.

I would recommend making your own signal routing box with suitable footswitches - either hard-switched multipole jobs or cold-switched relays - and put the isolation at the end of the whole mess where the signal isolation is critical.

You don't mention if any of the delays, etc., are also AC powered. If so, you may possibley have to isolate coming in, but I'd leave that til I tried it all out.

10/29/1999 2:12 PM

R.G.,

Thanks for the info.

Yes, I was planning on making my own routing boxes. I have plenty of Carling DPDT and even a few of Mike Fuller's 3PDT switches laying around.

All of the effects including the time based ones are stompboxes running off a common 9v supply (Signalflex), and the built in 9v supply on one of those B.C Rich effects switching pedal boards.

The amps are: BFSR, SFDR, and a SFBMR... all have 3-prong power chords and will most likely run off a common power source.

I was hoping that I might be able to get away with just isolating all the jacks from the chassis enroute to the amps but I guess that's not the case. Which is why I posted here!

Thanks again,

pHiL

10/29/1999 5:52 PM

Yeah, the real problem is twofold:
(1) the differing amounts of AC leakage from each amp making each ground just a tiny amount different and
(2) induced 60Hz because all that cable ground wire is a big inductive pickup loop

It's possible that you could get away with it in many circumstances, but sooner or later you'll set up somewhere and have a massive hum. The isolators are a slam-dunk, although you're paying extra for insurance.

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