Phase inversion

steve_k

steve_k

Inspired
Is the Axe so advanced such when running two amps together with odd gain stages that it will actually phase invert the combined output as is the case with a real rig?

If so, how to overcome it and invert the phase of one of the amps?


Thanks,
Steve
 
Filter block can swap the phase of L or R channel. For that to work, you'd need to pan the amps 100% left and right. Also, cab blocks have the delay control, that works perfect for this. It's a bit tricky to set by listening only, but it can be done. If you want to go nerd with it, you can pan your amps 100% left and right, and then record a clip, and see the result on your computer screen, one track will a few samples ahead of the other. Adjust the cab delay on that track until you get a perfect result. Then you can go back and back off the hard panning.
 
aziz said:
Filter block can swap the phase of L or R channel. For that to work, you'd need to pan the amps 100% left and right. Also, cab blocks have the delay control, that works perfect for this. It's a bit tricky to set by listening only, but it can be done. If you want to go nerd with it, you can pan your amps 100% left and right, and then record a clip, and see the result on your computer screen, one track will a few samples ahead of the other. Adjust the cab delay on that track until you get a perfect result. Then you can go back and back off the hard panning.
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thanks. don't want to go too nerd about it......will try a filter. there's also an invert in the enhancer block. will give them a try. for the delay, yep, i don't think it takes much to flip the phase. - maybe 0.05ms or so. will give one of them a go.
 
It might be best and easiest to pan both amps to center and then tweak the delay in one cab block until you like what you hear. If it only goes worse, put the delay back to 0 and tweak the other cab block.
 
aziz said:
If you want to go nerd with it, you can pan your amps 100% left and right, and then record a clip, and see the result on your computer screen, one track will a few samples ahead of the other. Adjust the cab delay on that track until you get a perfect result. Then you can go back and back off the hard panning.
Click to expand...

Does this mean that you've already done this with the Axe ? You already found "problems" of phase cancellation because of the amps and not because of the mixing of mics ?
 
Reversing phase alone makes no difference to tone. It only matters when your signal is mixed with another, such as parallel routing of effects. There's a phase reverse switch in (I think) global settings, so try this to confirm that it doesn't matter.

Mixing your signal with a short delay producers a frequency response with many notches, where some frequencies are cancelled and others are reinforces, so this is not the same as a phase reversal.
 
Clive said:
Does this mean that you've already done this with the Axe ? You already found "problems" of phase cancellation because of the amps and not because of the mixing of mics ?
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Yes, Sometimes with dual amp presets I end up with phase problems. Not reverse polarity, but enough delay in one amp to affect the tone through comb filtering. I don't know if it is from amps or IRs. Easily seen and adjusted in DAW. Motor drive in amp block does this too, set it to 0. My problems may have been related to that, I don't remember anymore.
 
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Sounds like a few have had the same issues. Will just stick to one amp on at a time until I can figure it out.
 
The amps are always in phase and have equal latency. Same with the cabs if motor drive is off. With that said, phase (delay) and frequency response are inextricably related. An amp that has a much different frequency response to another amp will appear to have a different latency but this is an illusion. You can't measure delay by looking at the response in the time domain.
 
FractalAudio said:
The amps are always in phase and have equal latency. Same with the cabs if motor drive is off. With that said, phase (delay) and frequency response are inextricably related. An amp that has a much different frequency response to another amp will appear to have a different latency but this is an illusion. You can't measure delay by looking at the response in the time domain.
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thanks cliff. so, its an aural illusion then? since that is the case, i think it just a matter of finding and pulling down a frequency or range that may be unwanted using filters. maybe alter the L/R separation too.
 
steve_k said:
thanks cliff. so, its an aural illusion then? since that is the case, i think it just a matter of finding and pulling down a frequency or range that may be unwanted using filters. maybe alter the L/R separation too.
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I think L/R separation is the best place to start. If you do multiple takes with different amps then there are no issues but as soon as you've got the exact same input signal to two amps then there can be phase issues.
 
FractalAudio said:
The amps are always in phase and have equal latency.
Click to expand...

If I take two real 5150 III amps for instance, they don't have *exactly* the same latency because every amp is unique.
If I take two 5153 blocks in the Axe II, they have the same latency according to what you stated but If I split the signal to feed them with exactly the same signal input, will these two blocks have *exactly* the same frequency signature ?

Thanks.
 
Clive said:
If I take two real 5150 III amps for instance, they don't have *exactly* the same latency because every amp is unique.
If I take two 5153 blocks in the Axe II, they have the same latency according to what you stated but If I split the signal to feed them with exactly the same signal input, will these two blocks have *exactly* the same frequency signature ?

Thanks.
Click to expand...

Try this:
Setup 2 5153 blocks and pan hard left and hard right. Record the 2 into your DAW using separate tracks. Invert the phase of one of them, then play the two tracks together. If you hear nothing, then the responses from both amps are exactly the same.
 
Yes of course. My question was about the 5153 but I could have taken any other amp block. My question was more general.
 
Chris@KatsuKuriMedia said:
what is making you think it's possible that they could be different?
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When you press the "Rand" button on a calculator, you get a number. If you press the same button another time, you won't get the same number (you would be very lucky if it was not the case) and yet it's the same algorithm.
 
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