[Matt]

Hello, all.

I am interested in building an input switcher. I need at least four stereo inputs and would prefer a high-value but not high-cost solution for this. Small is best, so long as it doesn't interfere w/sound quality. I will be switching between turntable, CDP, digital piano and computer.

My ideal is "high on the price/performance curve" with an emphasis on getting this done for a relatively low cost (under $35 or so for parts).

I did a search for "input switch" and it came up with nothing of relevance I could see.

Please help.

Thanks!


- Matt

 

[null]

try this... http://headwize.com/projects/showfil...=cmoy7_prj.htm

it only has room for two inputs, but you should be able to tack on a few more without much trouble...

 

[Voodoochile]

If you use a C&K or similar switch, it won't be that bad (price-wise). A Grayhill is more, and the Elmas (Mike Percy) are similar or more than Grahill, but they are much more solid feeling than the C&K.

Get a three or four pole x the number of sources you wish to switch. Most of these have stop pins you can use to limit the positions if you need less.

What type of inputs will you use- RCA, mini jack, or a combination?

 

[Megaptera]

It may be difficult to balance well-contructed materials with your budget. I'm guessing you'll be using RCA jacks -- You can find some pretty cheap Switchcraft RCAs on Mouser (502-3501FR is about $16 for five pairs), and Alpha Taiwan rotary switches for about $4. That'd leave you about $10 for an enclosure and shipping.

I haven't used the jacks (I like Cardas CTFAs, but they're $8/pair), but the Alpha Taiwan 4p6t switch I used is nice and solid, but I heard a bit of crosstalk between the inputs -- I had a grounding problem at the time, though, which may have contributed to that.

The design itself is pretty simple. I would recommend using a 4p switch so that you don't have to join the grounds together at any point; otherwise, it's just a matter of wiring the jacks to the switch, and then the switch to the output jacks. There's no need for anything else here, just good mechanical components, steady soldering, and a case that will keep the interference out.

 

[Matt]

Actually, what I plan to do (oh yeah, thanks for the info so far!) is hardwire cat5 to the unit's end, then do custom ends where I must (the tt will take RCA, the piano will take mono 1/4" plugs, the CDP will take RCA and the computer will be miniplug. This way, with a few extra solder joints, I save plugs and such.

Naturally, I will leave the option open to later put on RCA jacks, but for now the unit end of the wires will be hardwired.

Other than that, I was mostly looking for a good (four pole, I guess, now that I know what to look for) switch with four or more positions. Can anyone just point me to a link? I am not terribly efficient searchign Mouser-type sites at this time. Also, a suitable enclosure and RCA/mono/minijack plugs. Maybe like a switchcraft-quality set...I am not using this on a super-high-fi rig, more like Grado SR-60 quality.

Regards,
Matt

 

[Megaptera]

Mouser and Digikey both have pretty easy search systems. Just type in a few keywords ("alpha taiwan rotary") and you'll get a list, and some possible catagories to break it down even further. It's just a matter of knowing what the important keywords are: the manufacturer name and a technical description/value is often enough to bring the search results down to a page or two. When in doubt whether something's what you need, just check it's datasheet.

The enclosure can be just about anything. Serpac and Hammond both make them, or you could use something you find somewhere. I'm a big fan of the Hammond 1455 series myself.

I like your idea of having the cables hardwired to the switch. I'd suggest picking up some strain relief as well -- it'll look nicer and won't jiggle around as much.

 

[Matt]

Of the given examples (C&K, Elma, Grayhill, Alpha), what is the best price/performance point? If there is going to be crosstalk on the Alpha, forget about it!

Also, please tell me where to buy the recommended switch for the best price, if you know off the top of your head. I honestly don't mind spending $25 or so for the switch, no biggie. I just get a little concerned when I see "$3" for the Alphas and then hear talk of crosstalk.

- Matt

 

[Nisbeth]

Have you considered using relays instead? You can the use any cheap switch to control the relays.


/U.

 

[AndyN]

Get some mercury-wetted relays. They are fast and electrically quiet. Rig them up so that they are shunted to ground until energized.

"The only reason not to use mercury-wetted relays is cost" -- M. Jones

The book "Valve Amplifiers" by Morgan Jones has about 2 pages of instructions on using relays for input switching. When in doubt, do what the BBC engineer says

http://www.firebottle.com/apf/apf_be...arch&locale=us

 

[Matt]

What is the difference between "shorting" and "non-shorting" switch? It looks like the four pole/five position switches are "shorting," vs. the 4 pole 3 positions which can be non-shorting.

Any idea what is best?

- Matt