Dual Amp Question

A

Andrew Foltz

Member
Hi I'm using an axe FX II XL

I just started experimenting with dual amps in a preset and I'm running into an issue/phenomenon.

Chain is as follows:

input-pitch-wah-filter-filter-Drive-Amp-Cab-some more edfects etc..-output
Amp-Cab
In the above I'm splitting the signal before the drive pedal and merging after the cab. The idea was to keep one amp more clean and the other more overdriven. What is happening is when I have both amps engaged and I engage the drive block the signal drops several DB. I confirmed this on the VU meters. When I have the 2nd amp bypassed this does not happen. the level stays the same/slight increase.

Is there a reason for this or a setting i am missing?

Thanks in advance.
 
I think I had a similar problem last week building a metal patch:
DRIVE+AMP+CAB in one row, just AMP+CAB in second row.
Main idea was blending a boosted 5150 with an unboosted Uber. Having the DRIVE OFF was fine and both amps blended really great. After enabling the DRIVE on first row the phase between them was not right. My solution? I just added the same DRIVE on row two with mix to 0%. Solved.

Maybe DRIVE block is doing some phase changes in addition to its main job?
 
I hadn't had that problem so far because when I do a dual patch I usually split the signal after the DRIVE block and share it between the two amps.
 
eloygperez said:
I think I had a similar problem last week building a metal patch:
DRIVE+AMP+CAB in one row, just AMP+CAB in second row.
Main idea was blending a boosted 5150 with an unboosted Uber. Having the DRIVE OFF was fine and both amps blended really great. After enabling the DRIVE on first row the phase between them was not right. My solution? I just added the same DRIVE on row two with mix to 0%. Solved.

Maybe DRIVE block is doing some phase changes in addition to its main job?
Click to expand...
That makes sense im guessing it has to do with how it processes stereo to mono and back
 
I don´t think it´s a stereo to mono thing and/or viceversa. I think only having a DRIVE block in one row get some phase issues.
Try to put the same DRIVE block with 0% and see if it solves the problem. Let me know!
 
eloygperez said:
I don´t think it´s a stereo to mono thing and/or viceversa. I think only having a DRIVE block in one row get some phase issues.
Try to put the same DRIVE block with 0% and see if it solves the problem. Let me know!
Click to expand...
I will try this, will prob mean i have to reduce my CPU load so may have to make a decision but ill see, thanks for your help!
 
eloygperez said:
I don´t think it´s a stereo to mono thing and/or viceversa. I think only having a DRIVE block in one row get some phase issues.
Try to put the same DRIVE block with 0% and see if it solves the problem. Let me know!
Click to expand...
I think another idea is to split after the drive block but only send to one side like have one amp L and the other R and repan in the cab block
 
Do you have Bypass Mode set to Mute in the Amp/Cab blocks?

If not, when you bypass then dry signal is passing thru that part of the chain.

The parallel row will add 6dB of level.
 
unix-guy said:
Yes. This...

If you're getting phase issues that could result in the overall level being less, I think.
Click to expand...

Exactly.

I tend to make dual amp patches sharing the same pre-amplifier stuff and I split just after. This way you don´t get any phase issues blending them. Problem appears when you have only one row with drive blocks. I tried adding the same drive (but mix to 0%) to the second row because I experienced a similar problem with certain VST chains in the past and this kept the two "rows" in phase.

BTW I tried the same concept using real pedals instead of drive block and there were no phase problems this way.

REAL PEDALS -> AMP -> CAB (row1)
AMP -> CAB (row2)
 
666was999 said:
The drive isn't turning the phase. It adds a tiny little bit of latency. So the phase gets shifted some.
Using two drive blocks corrects that by shifting both signals.
Click to expand...
This for sure.
Then that added latency makes the two rows not perfectly in phase.
 
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