Dialing in a Two Amp rig? Tips and Tricks?

[JTyson]

Yeah I'm curious to this as well! I set up my dual amp rig, and while I can test at crushing volume I haven't taken it to practice yet so I'm uncertain how it sits with band. The M90 can be a little dark, so by itself I ran the edge/presence pretty high, but the DSL has a lot of cut so I'm tooling around setting up the M90 more to compliment the DSL but when I hear the M90 alone it sounds really dark know.
I'm just scared if both are bright that could be quite unpleasent but then if the sound guy sucks one amp will be dominate the mix!

Because most sound guys have no idea what you are doing .... or understand the mix the way you do ..... I recommend using your own microphones and a small mixer to send your sound to the mixing board. Other wise the mix is never even close.

One thing I use is an ABY pedal that has phase switching capabilaties. When amps are out of phase they sound completly different. Out of phase it sounds like stereo and loses solid bottom end, in phase they come together and crush 3rd world countries. I like amps better in phase but can see a point to out of phase. Either way it is nice to have the ability to change it up.

I hear this one is good .... I have never used it ...

http://www.tonebone.com/re-bigshot-aby.htm

I have one of those, they are really hard to beat for the money. The phase switching works well, and the ground lifts keep the noise down

 

[reverymike]

Here's the thing to consider about phasing when running a two amp rig.

Anytime you add or subtract a gain stage, the phase will flip. SO. . .if you are running say, a Bogner and an old Marshall, you can make sure they are in phase by using an Axess BS-2 (it has a phase flip button) -- once the amps are in phase, leave them as they are -- if you need to add a boost, do it in front of BOTH amps in order to keep them in phase. If you are running this rig, and change channels on the Bogner, you'll go out of phase. There are ways around this (running something to flip the phase in the loop of a switcher), but it can get complicated.

 

[ibanez4life SZ!]

So there is also a possibility of the phase changing when I switch channels? I guess that makes sense according to the gain stages.

Keeping two amps in phase, when taking channel switching an all into account, really is a pain huh?

 

[petejt]

Here's the thing to consider about phasing when running a two amp rig.

Anytime you add or subtract a gain stage, the phase will flip. SO. . .if you are running say, a Bogner and an old Marshall, you can make sure they are in phase by using an Axess BS-2 (it has a phase flip button) -- once the amps are in phase, leave them as they are -- if you need to add a boost, do it in front of BOTH amps in order to keep them in phase. If you are running this rig, and change channels on the Bogner, you'll go out of phase. There are ways around this (running something to flip the phase in the loop of a switcher), but it can get complicated.

So are you saying that using any pedals in a 2-amp rig, would affect the phasing?

I have a MarkIV and a JCM800. If I run the lead channel & reverb on the MarkIV (w/o effects loop), will it be in phase with the JCM800?

 

[reverymike]

Here's the thing to consider about phasing when running a two amp rig.

Anytime you add or subtract a gain stage, the phase will flip. SO. . .if you are running say, a Bogner and an old Marshall, you can make sure they are in phase by using an Axess BS-2 (it has a phase flip button) -- once the amps are in phase, leave them as they are -- if you need to add a boost, do it in front of BOTH amps in order to keep them in phase. If you are running this rig, and change channels on the Bogner, you'll go out of phase. There are ways around this (running something to flip the phase in the loop of a switcher), but it can get complicated.

So are you saying that using any pedals in a 2-amp rig, would affect the phasing?

I have a MarkIV and a JCM800. If I run the lead channel & reverb on the MarkIV (w/o effects loop), will it be in phase with the JCM800?

If you're adding or subtracting a gain stage to one of the amps (and not the other), then your phase will switch. With a BS2 you'll be able to correct the phase with whatever channels you want to use, but then say, if you hit a boost on one of the amps, you'll flip phase. Or, if you go to your clean channel on one of the amps, you'll flip the phase. The simplest way to prevent this, is to get your channels in phase and don't add or remove any gain stages, unless you're doing so in front of BOTH amps. I am 99% sure that if your amps are in phase and you hit a tubescreamer or something in front of both amps, the phase won't change.

 

[petejt]

Here's the thing to consider about phasing when running a two amp rig.

Anytime you add or subtract a gain stage, the phase will flip. SO. . .if you are running say, a Bogner and an old Marshall, you can make sure they are in phase by using an Axess BS-2 (it has a phase flip button) -- once the amps are in phase, leave them as they are -- if you need to add a boost, do it in front of BOTH amps in order to keep them in phase. If you are running this rig, and change channels on the Bogner, you'll go out of phase. There are ways around this (running something to flip the phase in the loop of a switcher), but it can get complicated.

So are you saying that using any pedals in a 2-amp rig, would affect the phasing?

I have a MarkIV and a JCM800. If I run the lead channel & reverb on the MarkIV (w/o effects loop), will it be in phase with the JCM800?

If you're adding or subtracting a gain stage to one of the amps (and not the other), then your phase will switch. With a BS2 you'll be able to correct the phase with whatever channels you want to use, but then say, if you hit a boost on one of the amps, you'll flip phase. Or, if you go to your clean channel on one of the amps, you'll flip the phase. The simplest way to prevent this, is to get your channels in phase and don't add or remove any gain stages, unless you're doing so in front of BOTH amps. I am 99% sure that if your amps are in phase and you hit a tubescreamer or something in front of both amps, the phase won't change.

Ah ok, thanks.

Well the MarkIV has three gain stages for the Rhythm 1 & 2 channels (I think), and 5 gain stages for the Lead channel. So I guess that if I run it alongside a single-channel amp such as my JCM800, without adding in the effects loop, then they will still be in phase?

I can't test it at the moment because my MarkIV is in storage.

 

[reverymike]

It depends on if you change channels on the Mesa. You can set it up to be in phase in any combination of the channels, but as soon as you switch channels on the amp, you'll flip the phase. You can set it up using any of the mesa channels and the effects loop if you want, you just won't be able to change anything after that (unless it's in front of BOTH amps).

Example; Last night I ran my Bogner 101 on the blue channel with boost and loop on, alongside a 78 JMP 2204. I got them in phase, and then, left the amps channels alone, and just clicked on an overdrive on my pedalboard for solos. It stayed in phase all night.

 

[D-Rock]

I like running one amp that has a super tight and responsive high gain tone, then blend it with another amp that has way less gain, but is really thick and fat sounding.
Similar to what Mick Mars did. He ran his Marshalls with old Garnet amps wide open.

 

[1big1]

i have a tonebone head switcher. while it's nice to be able to use the iso transformer to prevent ground loops between heads and the phase switch.. it does have a down side. it tends to suck some of the tone.. especially treble.. because it's a passive box. you can increase the treble on the amps to compensate.. but my feeling is that it also changes the feel of the amp by making it feel a bit spongier. i would suggest a lehle.. or something along those lines if feel is important.

 

[rottingcorpse]

i use a custom amp switcher made by jm products (dropd) in the detroit area.

i come out of my guitar into a noise gate, then into this switcher. i dial in each amp to sound it's best, for me anyways. i do dial back some of the gain, and keep the mids at least at noon-ish. i run a marshall kerry king and an engl powerball on the 2 outside stacks. the middle stack get a different head according to whats new, or whats turning me on at the moment (will be slapping a titan custom up there when i get home in 2 weeks to see what the fuss is about). the forth channel runs a single 4x12 and an isp sub like a side fill with a madison prophecy or laboga mr.hector head with a decimator in the loop. i have not run the 5th channel yet, as i have ran out of space for another cab on the other side of the room (i keep my liquor over there).

it took dropd a while to make this unit for me, and it went though several mods to make it noise free. i love it so much i am ordering another one as a backup. i do have the voodoo labs amp switcher, but i like this unit better. i have been trying to stay away from building another rack system, or i would have bought a radial jd-7.

 

[petejt]

It depends on if you change channels on the Mesa. You can set it up to be in phase in any combination of the channels, but as soon as you switch channels on the amp, you'll flip the phase. You can set it up using any of the mesa channels and the effects loop if you want, you just won't be able to change anything after that (unless it's in front of BOTH amps).

Example; Last night I ran my Bogner 101 on the blue channel with boost and loop on, alongside a 78 JMP 2204. I got them in phase, and then, left the amps channels alone, and just clicked on an overdrive on my pedalboard for solos. It stayed in phase all night.

Ok.

What I'm trying to understand is when and how many times the phase flips inside the amp. For every gain stage, the phase flips once, from what I understand.
If both amps have either an odd number of gain stages, or an even number (as long as they are both even, or both odd), no matter if one of the amps has more gain stages than the other amp, then the resultant phase will be the same for both amps.

So if I switch channels on the MarkIV, from Rhythm 1 (3 gain stages) to Lead (5 gain stages), there's still an odd number of gain stages. If the JCM800 also has an odd number of gain stages (3 I think?), then the phase for both amps will be the same. And therefore there will be no phase cancelling when both amps are run together?


I'm sorry if this seems like it's going round and round over logic....lol

 

[Sixtonoize]

Your logic is correct. As long as you're going between an odd number or even number of gain stages, the phase relationship is preserved. When you go from an odd to an even number of gain stages, the phase is flipped.

 

[stephen sawall]

For me I have found the only way to really see what it is doing with phase is try it both ways .... you ears well know.

I guess some of you understand now why people like Adam Jones does not change channels live and uses the volume on the guitar.

 

[reverymike]

It depends on if you change channels on the Mesa. You can set it up to be in phase in any combination of the channels, but as soon as you switch channels on the amp, you'll flip the phase. You can set it up using any of the mesa channels and the effects loop if you want, you just won't be able to change anything after that (unless it's in front of BOTH amps).

Example; Last night I ran my Bogner 101 on the blue channel with boost and loop on, alongside a 78 JMP 2204. I got them in phase, and then, left the amps channels alone, and just clicked on an overdrive on my pedalboard for solos. It stayed in phase all night.

Ok.

What I'm trying to understand is when and how many times the phase flips inside the amp. For every gain stage, the phase flips once, from what I understand.
If both amps have either an odd number of gain stages, or an even number (as long as they are both even, or both odd), no matter if one of the amps has more gain stages than the other amp, then the resultant phase will be the same for both amps.

So if I switch channels on the MarkIV, from Rhythm 1 (3 gain stages) to Lead (5 gain stages), there's still an odd number of gain stages. If the JCM800 also has an odd number of gain stages (3 I think?), then the phase for both amps will be the same. And therefore there will be no phase cancelling when both amps are run together?


I'm sorry if this seems like it's going round and round over logic....lol

You're right -- if by switching the channel, you add or subtract two gain stages, then you'll skip over the change. It just gets kinda tricky trying to figure all that out. But, yes, you are correct. Phase will flip each time you add or subtract a single gain stage, so you if add two, you should be fine.

 

[petejt]

Your logic is correct. As long as you're going between an odd number or even number of gain stages, the phase relationship is preserved. When you go from an odd to an even number of gain stages, the phase is flipped.

Thank you!

I thought it was just a matter of logic.