Newbie embarassing switch question

[racingintherain]

I'm building my first preamp from scratch. All done except putting in switch for input selection. Here I am confused. I decided on a rotary switch to switch 3 stereo sources. On recommendation for low cost decent switch I have this.



a 2 pole 5 position switch (GC 35-377). It has no datasheet.

Is this correct for my purpose? With 3 stereo inputs. how would i wire this switch? It has one pin in the center and 12 pins around the circumference. What pins are in/outs for +/- Source 1, Source 2, Source 3, and what pins are +/- output?

Thanks for any help on what I'm sure seems an ignorant question.

Regards,

Rain Race

[Geoff]

That is a standard Lorin (or similar) rotary switch. If it has one tag in the middle it is a one pole twelve way switch. Two tags in the middle would mean two pole six way.

The inputs are wired to the outer tags and the outputs to the inner ones, for your application.

If the switch is as you described, it will not suit your needs.

[Speedskater]

While i have to agree with Geoff, it looks like a 1P12T switch. The best way to check any switch before wiring is a multi-meter. I would not do even the simplest project without having a meter nearby.
Need a meter? Radio Shack has lots. Need a cheap meter, that national chain of outlet tools have them.

[racingintherain]

Thanks for the replies. I agree, lloked like a 1 pole 12 way switch to me too, even though packahing clearly says 2 pole 5 way and the image of it on the GN web site looks just like this one. Glad I'm not as ignorant as I thought.

Robert

[racingintherain]

Just a folllow-up. Am I right that to switch 3 stereo inputs I need a 2 pole 3 way (or more way) switch?

Thanks.

Rain Race

[john blackburn]

Some say it is better to switch both the signal and signal grounds, so you would need a 4 pole 3 way switch. If however your source doesn't have seperate signal grounds there would be little point in my opinion and you would be fine with a 2 pole.

I second the post about buying a multimeter before you go any further. By connecting a lead to one pole you can then continuity test each switch position and find out what switches to what and there are no mistakes made.

John

[Nordic]

SO while you are at it looking for the correct switches....

You allready had the first bit of advice, to be able to cleanly switch out sources you will need a 3 to 4 pole switch, as you have 2 channels... (3 or 4 as you may or may not want to split the grounds)

I would further narrow it down to 'make before break' switches to avoid clicks or pops when changeing source...

Swiches are commonly foud with poles and throws makeing up 12.

i.e. 1P12T
or 2P6T
3P4T
4P3T..

I agree with John, take $10 and go buy a meter.... even a $10 meter is usefull in the right types of tasks..

[racingintherain]

Thanks for the continued advice. I actually have a meter on-hand so will use it to good effect. To further clarify - 2 pole or 4 pole to switch stereo inputs? Is it just a question of preference as relates to switching grounds or will 2 pole not work.

Thanks,

Rain Race

[john blackburn]

If you can get a 4 pole 3 way use that to switch both signals and both signal grounds.

If you can only get a 3 pole 3 way use it to switch both signals and a common signal ground.

As for using a 2 pole and having a common unswitched signal ground I wouldn't like to say. I would imagine many would say it shouldn't be done and as I am a beginner myself I don't feel qualified to comment.

Nordic recommended the use of a "make before break" switch, this makes the "next" input contact before breaking the existing one to ensure you never show open circuit to the amp inputs. I hope that makes some sense, I'm sure someone will be along with a comprehensible explaination soon but until then that will have to do.

Hope it's of some use.

John

[MoodySteve]

You could use the switch you have if you used relays to switch the signals rather than the switch itself. This would also offer the advantage of considerably shorter low-level signal wire, since you could put the switch up front and have the relays right below the RCA inputs. This could help minimize EMI injected into the input from the transformer.