Dual-gang linear pot as splitter and front/rear balance control?

[booksix]

My head unit only has one stereo pair of RCA outs. My 4 channel amp is currently setup to internally split the channel 1-2 input to run channels 3-4 as well. The problem is I badly need front/rear fade control (which i obviously don't get with a single rca out - just left/right). Can I simply use a dual-gang, linear taper pot between the head unit and the amp to split the signal and provide a simple and cheap fade control? It would be somewhat like a volume control but instead of returning the 'extra' signal to ground I'd send it along to its own channel. Sorry if I'm using the wrong terminology but I think someone will be able to make sense of this! Also, what should I use? 50K? 100K?

[AKHeathen]

hmm, i take it you have a certain pot in mind that you have used? or by "dual-gang, you are referring to a double pot, not a dual gang home audio speaker controller. those, do not return the signal to ground, rather adjust resistance. are you utilizing the r/l balance? if not, i would simply use y-splitters and run right to 1/2, and left to 3/4, and then you could just use balancing as the fade control. another option would be to pick up a cheap line-driver, or basic similar equalizer. the once popular 1/2 din units used to often have a fader built-in and sub output, all switchable. i have not played with pots too much, other than replacing with the proper ones. i would suggest looking at different ones, you may just find a ballncing double pot. as far as i know, 100ohms should get you full attunation, however, a linear pot will give full signal to one side at a time, and only 1/2 signal when centered. if you have enough gain adjustment for that, then you could pick up a cheap rca in-line adjuster, and it will have 2 channels. you should be able to upen it up and tap into the unused legs (no guarantee it has them) and that would do what you want, just make sure the signal is on the centered leg.

[booksix]

No, its a dual pot (as in two pots stacked with a single shaft running through both). As far the the ground thing I was talking about, see the diagram in this link:

Volume control.

That circuit is using a dual gang pot to control volume. It seems to me that whatever signal isn't sent from the input to the amp is sent to ground. What I want to do is use a similar circuit with a linear pot but, the additional signal is instead sent to another channel. I figured, given a linear pot, centering the pot would send equal the signal across both output pins and rotating the pot either way would favor one channel or the other (giving me my front/back fade).

Would this degrade my signal? It was my understanding that using splitters would not affect the signal voltage and therefore the amp would not no any difference so I was hoping I could do the same with a pot.

[Perry Babin]

The Potentiometer page of the site shows how to make an inline level control. You'll split the signal and insert the potentiometer between the y-cable and the rear channels of the amp.

With the circuit on this page, the signal isn't shunted to ground. The wiper of the pot simply taps off of the resistive element at various points to produce the desired output level.

[booksix]

Ok, so basically run a splitter with a volume control in line with the rear channel to lower its level and bring it audibly to the level of the unaffected front channel?

[Perry Babin]

Yes.