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Passive In-Out-Thru Switch-Box

post #1 of 9
Thread Starter 
Hey all,

i'm not sure, if this has been discussed already, but i couldn't find anything related on the last 4 pages. So here goes:

I'm currently building a Starving Student. I allready have a HiFi amp with speakers connected. I need my PC's onboard audio (needed for a special game which doesn't work with other cards/dacs) i'm adding a DAC and have a Guitar which i have to plit to either onboard audio or a ADC.
What do i need? I want a box where i plug all of this into and then select via knobs which input goes to which output. Basically 3 selectable rca inputs, 3 selectable rca outputs. A 1/4 Jack input to 2 switchable 1/4 Jack Outputs.

My question: Will i be able to buy 3 switches (stereo 3 position turnable switches) and wire all jacks directly to them or do i need any kind of circuitry/active part to make this function properly?

Thanks in advance for any input procided!

Rock on
Dominik
post #2 of 9

There's plenty of passive analog audio switchboxes out there, I built one a number of years ago with 5 input pairs of RCAs and 3 output pairs. No active internal circuitry was necessary. There are even passive pre-amps out there that offer passive attenuation. These sound a little bit different than active line stages, but they can work just fine depending on the impedance of your system. 

 

A small note, barely worth noting, but I've read that in rare cases with certain phono pre-amplifiers, the interconnects and wire between the switchbox and phono pre needs to be at max a certain length, otherwise the result is attenuation and phase shift because of excessive capacitance.

post #3 of 9

I am in the process of building one right now. 2p6p rotary switch, DPDT switch, and some shielded wire. 2 inputs, 6 outputs. As soon as I finish machining the plexi I will put it all together. Make sure to use shieled wires....

 

Note: it is cheaper to buy  for $15 then to make one. 

post #4 of 9
Quote:
Originally Posted by HiGHFLYiN9 View Post
 

A small note, barely worth noting, but I've read that in rare cases with certain phono pre-amplifiers, the interconnects and wire between the switchbox and phono pre needs to be at max a certain length, otherwise the result is attenuation and phase shift because of excessive capacitance.

 

Phono-stages or Tube DACs that attempt to drive the output directly off the plate of the output tube can have this issue. 

 

I have also experienced a similar problem with an op-amp phono-stage I designed when hooked up to a VERY long interconnect (like 15ft) because I did not include an output resistor :facepalm: 

 

Good design solves both problems, and as you say the problems are somewhat rare if you are just aware of the limitations of certain gear. 

post #5 of 9
Thread Starter 
I know that it is cheaper to buy one. But generally I hate the cheap plastic that is used in such products. Besides that I like building this myself for satisfaction...

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post #6 of 9

Elma/Goldpoint make some great, high quality switches if you want to part with a few more $$

post #7 of 9
Quote:
Originally Posted by domsch1988 View Post

I know that it is cheaper to buy one. But generally I hate the cheap plastic that is used in such products. Besides that I like building this myself for satisfaction...

Gesendet von meinem HTC One X mit Tapatalk 4

 

Hey man I am right there with you. But for $20 you can buy a nice metal one, just FYI. 

 

Expect to pay ~$5 for a good DPDT switch. ~$7 for a quality rotor switch. $.50 per pair of gold plate RCA jacks, $.40/ft of good shielded wire. and $? for a box, or build your own. I got 2x24x1/8 maple for $16 shipped. but that will require lots of drilling and assembly, and staining, and so on.  

post #8 of 9

Any recommendations on good 2 post rotary switches? I don't really want to spend $50+ on a switch, but at the same time I'm hesitant to go with the cheap ones on Mouser or Digikey. 

 

I spent a while this afternoon looking for a nice RCA switch, but they were all cheap plastic or way more expensive than I want to spend. 

post #9 of 9
Quote:
Originally Posted by earthpeople View Post
 

Any recommendations on good 2 post rotary switches? I don't really want to spend $50+ on a switch, but at the same time I'm hesitant to go with the cheap ones on Mouser or Digikey. 

 

I spent a while this afternoon looking for a nice RCA switch, but they were all cheap plastic or way more expensive than I want to spend. 

Electroswitches makes good stuff. I used this guy in mine. 

 

http://www.mouser.com/Search/ProductDetail.aspx?R=C6P0206N-Avirtualkey69000000virtualkey690-C6P0206N-A

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