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General Category => Technical topics => Topic started by: Noskipallwd on June 29, 2012, 07:13:10 PM

Title: Multiple source and multiple output switchbox
Post by: Noskipallwd on June 29, 2012, 07:13:10 PM

Hello, as the title states i would like to build a multiple source/output switchbox. My plan is to use 2 Elma rotary switches that have adjustable positions (2-6). My question is, will I run in to any impedence issues, or any other problems I could encounter? I appreciate any help folks can give.

Cheers,
Shawn

Title: Re: Multiple source and multiple output switchbox
Post by: Pfenning on June 30, 2012, 04:34:23 AM

I built a device just like you are describing. I reclaimed a dead satellite tv receiver and stripped all the guts out. I made an aluminum face plate and sanded to have a brushed finish look. I used a rotary position switch (I can't remember where I got it) and wired 3 inputs to it. I wired up a single output, and installed it. It works great. I run my "lower" quality sources through it like our Wii, satellite, and Pandora for back ground music. I really haven't noticed any degraded sound, and I watch tv through it quite a bit. Good luck.

Pfenning

Title: Re: Multiple source and multiple output switchbox
Post by: Noskipallwd on June 30, 2012, 05:00:56 AM

Thanks for the reply, pfenning. This is going to be for my main system. 3 sources, TT and Eros; Squeezebox and Dac; and CD player. 3 outputs, Crack; another HP amp; and my speaker set-up. I just want the signal to go through as unmolested as possible. That is why I chose the Elma switches. I have read where some folks have had impedence issues with passive preamps, and wondered if that was a concern with this device.

Cheers,
Shawn

Title: Re: Multiple source and multiple output switchbox
Post by: Grainger49 on June 30, 2012, 06:41:10 AM

If only one source is connected to one amplifying device at a time you should have the same impedance you would plugging them in directly, plus a fraction of an ohm for the extra connections in the switcher.

Title: Re: Multiple source and multiple output switchbox
Post by: Noskipallwd on June 30, 2012, 07:13:39 AM

Great! Thanks Grainger, so without a pot, your only adding the small resistance from the added wiring and switches, makes sense. Ordered the switches, already have the jacks and a case.

Cheers,
Shawn

Title: Re: Multiple source and multiple output switchbox
Post by: Jim R. on July 01, 2012, 04:40:21 AM

Hey Shawn,

Best way to do this for the absolute cleanest signal is to make all switches double pole and switch grounds and hots for every input and output.  Keeping wiring very short (and use silver (like that tsp you have) and run all the shield grounds to one point and ground it directly to a wall outlet -- not one of the pieces of gear.

I'd go as far as to build it out of wood witha copper top, with the switches near the back panel with shaft extensions for the knobs.

Hey, can you shoot me the url for the place where I can get the brass mounting screws for the 2m black?

Take care,

Jim