My amps are out of phase

[benduncan]

I've been running a two amp/cab setup lately, a Mesa Triple Rec and a VHT Pittbull UL, but they are out of phase. Up until now I've just been inverting the phase on my mic pre, but it still sounds off. I think that the amps are bleeding into each others mics, causing them to still be a little out of phase even with the switch on the pre. I tried using blankets to separate them a little more, but they're so loud that it doesn't matter. Putting them in separate areas is not an option

I checked all eight speakers in my 4x12's with the battery test, they all check out. Anyone know an easier fix than buying an ABY box with a phase invert switch? I'm already using my Voodoo Labs GCX for amp switching, so it would be mostly redundant. I know that I can just re-solder the cab(or speaker cable) and reverse the polarity, but I'd like to avoid that if possible.

 

[Tone Monster]

Resolder one end of your speaker cable. It's easy and really the only way. Some amps will always be outta phase with each other...

 

[tubortski]

http://www.soundonsound.com/sos/apr08/a ... tified.htm

 

[paulyc]

You could have an amp tech put a phase switch on the output of one of the amps...or make a little box (like the size of an MXR pedal) with a 1/4" jack on each end to plug the existing cables into and reverse the phase in the box.

 

[benduncan]

Well, I got impatient and ended up reversing one of my speaker cables. I didn't really want to do that because it's a nice cable and I'm not great at soldering, but oh well. All other options would have taken at least a week, since I'd have to order something or wait for a mod.

You could have an amp tech put a phase switch on the output of one of the amps

This would be ideal, long term. I'm going to look into that.

Thanks guys.

PS They sound great now!!

 

[Tone Monster]

Awesome!!

 

[steve_k]

Thing is though, the odd number of gain stages with the two amps. You have fixed the phasing in the amp duet's current state by altering the output cable or even the output jack. If you change channels on one of the amps, then you are going to go out of phase again. Best way to handle this (if you need to switch channels) is with an RJM Y-Not and have Ron to do it with the phase reverse mod so it switches on the fly as programmed by you.

 

[benduncan]

Ah! I hadn't changed channels yet! But it looks like they don't make the Y-Not anymore That would be perfect though

Thanks

 

[paulyc]

They are supposed to be bringing it back, give them (RJM) a call to find out when.

 

[Ventura]

Lehle splitters...

/EOM

 

[Devilinside]

Ah! I hadn't changed channels yet! But it looks like they don't make the Y-Not anymore That would be perfect though

Thanks

I've got one that Ron modded for me for this exact same reason.
My Fortin bones and DSL was out of phase on certain gain stages. I no longer need it if I can round it up are you interested?

 

[benduncan]

I've got one that Ron modded for me for this exact same reason.
My Fortin bones and DSL was out of phase on certain gain stages. I no longer need it if I can round it up are you interested?

Thanks, I'd love to pick it up but I'm going on a trip this month. That means no extra money for about a month

Man it's tough to get two amps blending really well or maybe I'm just not used to my new cab. Just when I think I got everything sounding "great" I notice another frequency that I want to get rid of. Then I go to far and end up with only mids, lol

 

[Ventura]

Lehle S-Go-S....

JUST saying....

 

[benduncan]

Lehle S-Go-S....

JUST saying....

Lol, I saw the first time but forgot to reply. Looks great but do you know if the phase inverter can be controlled via midi? I can't seem to find that out

 

[Devilinside]

That's cool! By the way that was the mod that Ron did for my Ynot, making it midi controllable.

 

[benduncan]

That's cool! By the way that was the mod that Ron did for my Ynot, making it midi controllable.

Yeah, I assumed as much. I'll PM you

 

[benduncan]

GAH! I figured out why I keep hearing bad frequencies after I think that I have a good tone. I think that after hours of playing, my ears are shot, then the next day, I hear all of the crap that I couldn't before. And, I just realized that I forget to check the phase/distance of my mics after I reversed the polarity on my speaker cable. I spent about 2 hours today trying to figure this out, as you have probably guessed, I failed.

That's as close as I could get the waveforms. I didn't get to the mics individually yet, I was only using Audio 10 and Audio 13, the top being the VHT and the bottom the Mesa. Anyway, I tried many different combinations, moving them back and forth as far as a foot and a half. It seemed to only make a difference when compared with the signal from the same cab/amp but different mic. It seemed to make no noticeable difference when compared to the signal of the other amp. I tapped the mics with a pen to hear if everything was patched right, it was. I know I'm doing something wrong. I've only done this with multiple mics, not multiple mics/amps/cabs. Anyone know what the problem is?

This is starting to get frustrating, lol

 

[paulyc]

I'll ask a stupid obvious question, the cabs aren't pointed at each other, right ? And when you phase flip one of the mics it's still out ? I'm stumped...Are all the speakers Celestions ? No Jensen's or Emminence ? Cuz Celestions are actually marked "backward" with respect to most American speakers...the polarity is reversed compared to an old Jensen...

 

[benduncan]

I'll ask a stupid obvious question, the cabs aren't pointed at each other, right ? And when you phase flip one of the mics it's still out ? I'm stumped...Are all the speakers Celestions ? No Jensen's or Emminence ? Cuz Celestions are actually marked "backward" with respect to most American speakers...the polarity is reversed compared to an old Jensen...

No, they're in a big iso box that I built, kind of like a room within a room. One cab on top of the other, both facing the same way, facing a wall with foam, which is about three feet away. Yes, flipped phases. All speakers are Celestions. I checked all eight of them using a 9volt and they all popped in the same direction, backwards. I did find out that I was mistaken about which channels two of the mics were on, but they were both on the mesa, so I don't think it would have effected my problem. I took some screen shots

Here, the mics on the VHT are as far up to the grill as I could get them without touching. The Mesa's mic is about 8 inches back, yet the Mesa's signal is coming in earlier.

Here is what it looks like after I pull the VHT mics back about two inches back

VHT mics about 4-6 inches back

Here, the VHT mics are about a foot, foot and a half back. Further than the Mesa's mic yet it is STILL the same

But if I move the first mic closer, this happens

What the hell is going on? lol. It's gotta be just some stupid small detail that I missed or something

 

[paulyc]

Is one of the amps significantly louder than the other ? Can you take some of the speakers out of the iso box and record a different way ? I think you'd be better off with two 1x12 cabs with speakers of sufficient wattage to handle the volume of the amp being played into them. Can you time shift (delay) the Mesa signal in the DAW to correspond to the VHT waveform ? None of these speakers are re-cones, right ?