[Megaptera]

Good to know, thanks

Regarding the switch, the 4p6t I got from Mouser is Alpha Taiwan switch #10WR046 (both Mouser and manufacturer number) and cost US$3.17. I'm no judge of rotary switches, but it's got a nice hefty feel to it.

 

[skyskraper]

ive got one of the pen's winging its way to me now from melbourne.

regarding the switch, i just want one atm so ordering from mouser is a last resort after i check all the AU suppliers. its just not economical for me to order one part from there and i have everything else i need atm. although i might need some opamps soon//////////

 

[Megaptera]

That makes sense -- I hadn't realized you were in Australia when I first suggested it. Hopefully the info I gave you will be enough to track it down somewhere else.

 

[skyskraper]

sorry i should have made that clearer from the start

 

[andante]

I'll be using 3P4T Lorlin or similar switch as input selector to my yet-to-be-built M cubed amp/preamp. The question remains, shorting or non-shorting? I would imagine non-shorting, so different inputs never "mix". Is that correct?

Another question I have is for output selector switch (between 1/4" front jack and rear RCA outputs). Should I switch ground (SPDT) or L/R channels (DPDT) or all 3 (3PDT)? Shorting or non-shorting?

Thanks!

 

[tangent]

Quote:

Originally Posted by andante I would imagine non-shorting, so different inputs never "mix".

Yes. You want a shorting switch in, for example, a stepped attenuator. But for an input swtich, non-shorting is best.

Quote:

Another question I have is for output selector switch (between 1/4" front jack and rear RCA outputs).

If that's going to work at all, you want to switch the ground. You will connect all three throw lugs on the 1/4" side to the output jack, but only the left and right throw lugs to the RCA outputs. If you switch the ground through to the output jacks, you will be shorting out the ground channel, which will probably make it misbehave. But there's also the possibility that the amp just won't work well as a preamp in your setup. 3-channel amp designs are for driving passive loads, not for being a preamp.

EDIT: The output RCA grounds would be connected to the input ground, in this case.

 

[skyskraper]

non shorting = break before make.

thats what i ended up using.

 

[andante]

Quote:

Originally Posted by tangent If that's going to work at all, you want to switch the ground. You will connect all three throw lugs on the 1/4" side to the output jack, but only the left and right throw lugs to the RCA outputs. If you switch the ground through to the output jacks, you will be shorting out the ground channel, which will probably make it misbehave. But there's also the possibility that the amp just won't work well as a preamp in your setup. 3-channel amp designs are for driving passive loads, not for being a preamp. EDIT: The output RCA grounds would be connected to the input ground, in this case.

I'm trying to understand your reply, but it is a bit over my head...

I really meant a set of binding posts, rather then RCA plugs, in the rear. I am considering using a yet-to-be-built M3 amp to drive bookshelf speakers. I was hoping to set it up to, with one flick of a switch, completely bypass Modified Linkwitz Crossfeed (thus giving me a few extra dB), and also increase gain to a value suitable for speakers by switching appropriate resistors).

Now, if one were to use a headphone amp as a preamp, would one actually link input ground to output RCA ground, and output L/R to output RCA L/R? It seems counter-intuitive, but I do not understand enough about electronics to figure out why.