2 channel input w/ mix

[EFK]

Can someone tell me what kind of input jack I would need to feed a 2-channel amp, say a JTM45 with high inputs only (1 per channel) and add a 3rd input which is a mix for both in parallel? Can I do this with typical Marshall 4-lug Cliff jacks? I tried for a while today to figure this out (w/ those Cliff jacks) and I'm stumped.

[Joey Voltage]

Can someone tell me what kind of input jack I would need to feed a 2-channel amp, say a JTM45 with high inputs only (1 per channel) and add a 3rd input which is a mix for both in parallel? Can I do this with typical Marshall 4-lug Cliff jacks? I tried for a while today to figure this out (w/ those Cliff jacks) and I'm stumped.

You can do it with three regular switching jacks. First jack to one channel, the switch lug of which is connected to the tip lug of the jack for the second channel, the switch lug of which is connected to the tip lug of the third jack. the third jack switch lug is connected to ground. It is kind of confusing in writing. If you need me to, I can try and draw it out for you.

[EFK]

Are you talking about plain old uninsulated jacks? I'll have to think on that - would do away with the sleeve connection as that would just be to chassis. I've seen it done with uninsulated jacks. The reason I was trying to use these Cliff jacks is I want it all insulated from chassis; I was trying to mount the 1M resistors for each input on the jack as well.I had it all figured out from the hot side, unfortunately I couldn't come up with a 'switching' ground system and my ground kept bleeding back into my inputs. That probably doesn't make sense.

[EFK]

Got it! Works perfectly, 1M on the jacks and all. I probably should feel stupid for taking so long to 'get it' but I'm happy anyway.

[Joey Voltage]

Got it! Works perfectly, 1M on the jacks and all. I probably should feel stupid for taking so long to 'get it' but I'm happy anyway.

you only need one 1M resistor for the whole thing. I will draw it out tonight, or by hand and scan it.

[Joey Voltage]

Here you go, the DPST are there to represent the run of the mill plastic cliff switch jacks marshall and countless others use

[beefwhiff]

With the above config., the top jack is useless. It does the same thing as the middle jack. Plugging into the bottom will only give U1. Middle jack = U1 + U2. Top jack = U1 + U2. Or am I missing something stupidly obvious?

[Joey Voltage]

With the above config., the top jack is useless. It does the same thing as the middle jack. Plugging into the bottom will only give U1. Middle jack = U1 + U2. Top jack = U1 + U2. Or am I missing something stupidly obvious?

No you are correct I drew it in haste last night, and realized it later after I posted it. I forgot how I originally drew it out, I will fix it tonight.

[Joey Voltage]

Alright I tracked down my notebook of sketches, and surprise surprise, it is different than how I remember it LOL, it is actually three 1M loads, and three cliff jacks, I'll post it anyway, but seems as the op has it working well.

[Gaz]

Here is a good example from Mhuss' site.

[Joey Voltage]

Here, and no additional loading... that is if I drew it correctly