dual amp vol pot value matching questions

[castlewalls]

I have 2 10 watt practice amps, one is a Peavey Backstage & the other is an Ibanez IBZ10G. I put both heads into a single cabnet and joined the inputs. Basically the guitar plugs into an input on the head cabnet, then runs into the input of a Digitech RP150 effects pedal and each output (left & right) from the pedal goes into the separate amps. The output from each amp head goes to separate (home-made 1x10" & 1x12") speaker cabnets.

My question is: the volume pot values for each amp is different. The Peavey has a 50K & the Ibanez has a 100k.
So, I have to adjust the volume balance between the 2 amps to attain a balance of volume between the speaker outputs.

I have a 250k stacked volume pot (lying around in my spare parts drawer) i was thinking about wiring it into the 2 amps (replacing the existing amps V-pots) so 'hopefully' the volume would be the same between the 2 amps just by turning one volume control. 250k may be to much? I'm good at building & soldering but the electronic theory eludes me. Should I go with a stacked 50 or 100k pot instead?

Here's some pics of the head cabnet: (provided the link will post)

home.comcast.net/~castle.walls/cabnets/index.html

I just realized that using a stacked pot for the volume control of both amps may cause a ground problem(?)

For the power cables of both heads, i cut them short and wired them into a typical house wall electrical socket. I then took the remaining 2 power cable lengths and spliced them together to make a single long power cable with a male plug on both ends.

This cable plugs into the electrical socket to provide power to the pedal (which also plugs into the socket, check the pics out!).

Now my thought about the ground problem is tying the 2 amps input grounds together at the stacked pot, will that cause a problem? I'll disconnect the existing pots from the respective amps & run wires from the 3 pcb circuit holes - shielded I think at least just because of the length the wires will need to be and also that the stacked pot will be mounted outside of either amps metal casing (not that either of the amps chassis only covers the top and back of the innards, so not much sheilding to begin with).

The amps sound pretty good & full and louder than I thought with a minimum of ground noise (with either both on or either one turned up or down).

So in addition to my first question, will 'joining' the ground of both amps at the volume pot affect or cause grounding problems?
Thanks,
-Jim,

[ashcatlt]

On question #2: you've already got at least one ground loop (inputs and AC power), possibly two (if metal chassis are touching). What's one more? But the two grounds don't have to meet at the pot. The two elements are completely separate. The metal case of the pot only needs to connect to one of the grounds for shielding purposes.

On question #1: a stacked pot will allow you to turn both amps up or down at the same time, but won't necessarily help to keep them balanced at any one setting, let alone through the entire range of the pot. There are too many other variables involved. Better might be to hardwire each amp to a set max volume where they sound balanced, and then use either a single or stacked pot to attenuate the input to both amps together. Even that may not work perfectly, but I think it's got a better chance.

[col]

If I understand the problem correctly, you might be lucky and find a dual gang 50/100k pot. I believe it is possible to order one-offs from Omeg. But, a cheaper option would be to order a triple gang 100K pot and parallel wire two of the pots together to form a 50K pot. Though, speaking as a non-electronics guy, I imagine that you might still not obtain the right balance between the two amps because there are bound to be some differences in how the volume increases with the two amps and speakers with each sweep of the two pots. It might be good enough, or not. I imagine someone else (someone that knows what they are talking about) might be better able to advise if this likely would work well.