Running two heads into one cab

ZEEGLER

ZEEGLER

Well-known member
I have a Mesa Rectifier oversized cab. It has 4 ohm stereo inputs. I was planning on running two amps into the cab and using an ABY pedal in front so that I could play either or both amps just with the stereo cab.

That would work fine except I was going to run my Roadster and my Rivera together, but the roadster doesn't have a 4 ohm output that you can use by itself. It is a pair of 4 ohm outputs that I assume must be used together?

Am I totally wrong here?
 
Above post is correct. The two 4 ohm taps are configured such that you can connect Qty: 1 4 ohm load to Qty: 1 4 ohm amp jack, or Qty: 2 8 ohm loads to Qty: 2 4 ohm amp jacks (two 8 ohm cabinets in parallel is a total load of 4 ohms on the amp). The mesa manual has a whole section on this, PDF for your amp is on their website.
 
I have the manual somewhere, just can't remember where. 😂

I appreciate the info. The Rivera is fine. It has a 4 ohm setting. Just the same, I'm gonna find the manual for the Roadster. Just wanna be sure.
 
ibanez4life SZ! said:
Above post is correct. The two 4 ohm taps are configured such that you can connect Qty: 1 4 ohm load to Qty: 1 4 ohm amp jack, or Qty: 2 8 ohm loads to Qty: 2 4 ohm amp jacks (two 8 ohm cabinets in parallel is a total load of 4 ohms on the amp). The mesa manual has a whole section on this, PDF for your amp is on their website.
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Mesa cab outs are meant to be used as follows.

1x16 ohm: 1x16 ohm cab
2x8 ohm: 1x8 ohm cab, or 2x16 ohm cabs
2x4 ohm: 1x4 ohm cab, or 2x8 ohm cabs.

So you are good to go. Just use one of the 4 ohm outs on the Mesa head.
 
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ZEEGLER said:
I have a Mesa Rectifier oversized cab. It has 4 ohm stereo inputs. I was planning on running two amps into the cab and using an ABY pedal in front so that I could play either or both amps just with the stereo cab.

That would work fine except I was going to run my Roadster and my Rivera together, but the roadster doesn't have a 4 ohm output that you can use by itself. It is a pair of 4 ohm outputs that I assume must be used together?

Am I totally wrong here?
Click to expand...
already been mentioned, but just to go over.

Most modern amps will have 1x16ohm output, 2x8ohm outputs, and 2x4ohm outputs. The outputs are generally in parallel, so it would be 2x16ohm cabs to see 8ohms at the amplifier, or 2x8ohm cabs to see 4ohms at the amp. I haven't seen a 32ohm guitar cab, so it makes sense there is only one 16ohm output. Same with 4ohm, I haven't seen any/many? guitar cabs rated at 4ohm, so there are 2 outputs so the amp can use 2x8ohm cabs. It could theoretically use one 4ohm cab, since the outputs are in parallel.
 
Yup, got it. It's all good.

According to the manual, it doesn't even matter that much anyway. It says that an impedance mismatch is okay.

I got everything set up last night, but haven't actually tried it out yet.
 
ZEEGLER said:
Yup, got it. It's all good.

According to the manual, it doesn't even matter that much anyway. It says that an impedance mismatch is okay.

I got everything set up last night, but haven't actually tried it out yet.
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This is true - Mesa transformers are robust/can handle reasonable mismatches without concern. There likely will be a slight difference in tone/feel with a mismatch - some of the Mesa manuals actually recommend this to further experiment with tonal range of amps. Enjoy the setup!
 
njshred said:
Running two separate heads into a stereo cabinet not wired as two independent monos, sounds like a potential ground loop buzz disaster. I would start with the volumes on “1” to check it out.
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The two stereo jacks on Mesa Rectifier 4x12 cabs are isolated. They have quite a few stereo poweramps, and wire their cabs accordingly to facilitate compatability.
 
I tried it out last night. Works great, no hum!

The phase switch on my ABY switch has me wondering though. When running both amps, it sounds good with the switch in either position. However, in one position, it's much louder and more open sounding. I assume that would be the "in phase" position?
 
ZEEGLER said:
I tried it out last night. Works great, no hum!

The phase switch on my ABY switch has me wondering though. When running both amps, it sounds good with the switch in either position. However, in one position, it's much louder and more open sounding. I assume that would be the "in phase" position?
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Yeah. Out of phase would cancel frequencies and make it wound quieter and weaker. It wouldn't phase cancel completely because each amp has its own characteristics, but the more you dial them in to sound the same, the more they would phase cancel out of phase.
 
I'm really having fun messing around with this setup. Running two amps together opens up so many tonal possibilities. I've been experimenting with EQing the amps completely differently to how I would running them individually. I tried using the Rivera with much more treble than usual, as it has a really tight top end, and then using the Roadster mainly for the lows and low mids. Sounds really good like this. Super thick, but very tight.

I'm using the DeLisle ABY box. I would highly recommend it for anyone wanting to run two amps, but not wanting to go with a full blown amp/cab switcher. It's transformer isolated, so no hum, buffered, so no drop in signal, and has the phase switch to keep the amps in phase.

This little guy right here.

aby-800_a8a41fc87ef63576b489b765e7f470a8.jpg
 
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