Author Topic: Amp Ohmage Troubles (Read 3713 times)

Tricalibur · « **on:** March 30, 2006, 03:02:40 AM »

I'm in a dilema; I sent the following e-mail to Marshall amps;

"I have a question about a possible set-up im working on for my amp rig. Right now im running a Marshall Mg100dfx straight into an MG412 cab. The amp is permanently set to run at 4 ohms and the cab is 8 ohm imp. By running my amp into this cab i know that i am cutting the power in half (50 watts power instead of 100). I want to find some way to run the amplifier into both the cabinent below it and the speaker attached to it at the same time to use full power. My plan thus far to enable this is to replace the 4 ohm speaker attached to the amp with an 8 ohm one(this way the amp will cut its output to the top speaker in half just as with the bottom cab), and then split the single output into two with a regular audio splitter and run into both the bottom cabinet and the top speaker simultaneously. The thing I am worried aboout is what kind of affect splitting the single output into two will have on the amp. Even if I am running into 2 8 ohm cabs will this make my amp overload?"

What do y'all think?

HJM · « **Reply #1 on:** March 30, 2006, 07:15:59 AM »

two 8 ohm cabs in parallel will give 4 ohms - I think that's what you'll end up with but check with a multimeter first.

Actually, the amp will run cooler and last longer driving 8 ohms rather than 4!

Tricalibur · « **Reply #2 on:** March 30, 2006, 07:37:58 PM »

true, but it will be running at half power. Could I just use an ab / y switcher pedal to split the one output u think?

HJM · « **Reply #3 on:** March 31, 2006, 12:40:19 PM »

As long as you run the internal speaker and the cab in parallel it should be fine. If you can draw a diagram I can check to see if you're going about it the right way - bit difficult by text!

Tricalibur · « **Reply #4 on:** March 31, 2006, 07:34:57 PM »

I have a diagram. Il try an get it uploaded soon.

Tricalibur · « **Reply #5 on:** March 31, 2006, 08:27:30 PM »

here it is:

HJM · « **Reply #6 on:** March 31, 2006, 08:52:44 PM »

as long as it's a y box you're fine, just double check your impedance using a multimeter before you turn on and use decent speaker leads - not guitar cables!!

I'd try and get a parallel box from studio Spares or Canford, you don't know if the A/B box will take the speaker current. Or solder up a Y speaker lead.

Tricalibur · « **Reply #7 on:** March 31, 2006, 09:05:19 PM »

any links 4 multimeter, y switcher etc.?