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Amp blocks out of phase?

unix-guy

Legend!
Last night I was playing around with adding a second parallel Amp block into an existing preset just for fun.

I have a preset with the Dizzy Blue v2 and another with the Shiver Clean.

I copied the block from the Shiver Clean and pasted it in parallel to the Dizzy.

The signal splits before the amps and is joined after. The rest of the chain is the same.

The overall character of both amps is similar as they were set.

The resulting sound was very "phasey". Turning off either Amp (both had Bypass Mode set to Mute) eliminated the phasey sound.

Is it possible that some amp models are out of phase with others?
 

unix-guy

Legend!
Does one of the Amp blocks have a Drive block before it?
Yes, one of them did. Turning it off also seemed to help but I wasn't sure if that was related - I thought maybe I just wasn't hearing it because the volume was much lower.
 

yyz67

Power User
I've always "wished" for dedicated invert / time align blocks.

Agreed and they would probably be very low CPU.

BTW, a filter block can do inversion.
Phase Invert – Controls the phase of the output signal with options for “NONE”, “LEFT”, “RIGHT”, ”BOTH”.​
 

dr bonkers

Fractal Fanatic
Vendor
@unix-guy & @steadystate
A quick way to phase align that may work for you pan each amp/cab path hard left and right.

Play a 30 hz tone through the preset and record a snippet.

Identify if the left side or right side is early and by how much.

insert a delay block with 100% wet mix before the early amp and delay by the amount shown in your DAW.

Record another snippet to ensure left and right are now aligned.

Return your preset panning to normal and play your instrument. This should solve such an issue.
 

mr_fender

Axe-Master
Mic Distance in the cab block adjusts a sub 1ms micro-delay for adjusting phase interactions. Try hard panning your amp blocks and using stereo input mode on the cab block.
 

steadystate

Fractal Fanatic
@unix-guy & @steadystate
A quick way to phase align that may work for you pan each amp/cab path hard left and right.

Play a 30 hz tone through the preset and record a snippet.

Identify if the left side or right side is early and by how much.

insert a delay block with 100% wet mix before the early amp and delay by the amount shown in your DAW.

Record another snippet to ensure left and right are now aligned.

Return your preset panning to normal and play your instrument. This should solve such an issue.
My issues don't involve the cab blocks, just parallel signals in general. I use my ears and the flanger blocks. Sometimes white noise as a source. It's easy to tell when even the highest frequencies are aligned or not as you sweep the flanger delay. Even if the polarities match, inversion can help confirm the sweep.
 

yek

Legend!
Yes, one of them did. Turning it off also seemed to help but I wasn't sure if that was related - I thought maybe I just wasn't hearing it because the volume was much lower.

That’s the cause.

Adding a Drive block in front of only one of two Amp blocks in parallel rows, with both Amp blocks engaged, may cause phase cancellation because of latency. Solution: add a bypassed Drive block to the other row.

https://wiki.fractalaudio.com/wiki/index.php?title=Amp_block#One_or_two_Amp_blocks
 

chkayleebear

Inspired
Solution: add a bypassed Drive block to the other row.

Since this is news to me and the first question I thought to ask was "which models use the least CPU?" I'll list the ones that use the least (2.4% as of Ares 10) here: FET Boost, FET Preamp, Hard Fuzz, Micro Boost, SDD Preamp. Honorable mentions are Bender Fuzz (2.5%), Blackglass B7K, and Octave Distortion (both 2.6%).

Source: https://www.dropbox.com/s/h9ncef0pk4frp62/Yeks_Guide_to_the_Fractal_Audio_Drive_Models.pdf
 

dr bonkers

Fractal Fanatic
Vendor
My issues don't involve the cab blocks, just parallel signals in general. I use my ears and the flanger blocks. Sometimes white noise as a source. It's easy to tell when even the highest frequencies are aligned or not as you sweep the flanger delay. Even if the polarities match, inversion can help confirm the sweep.
This technique will correct that too.
 

jlynnb1

Axe-Master
never really considered this. So I use two in mine mane preset, but don't have separate fx lines hitting them. one amp block is in the main row, the second below it parallel. signal splits right before them and right after, should I be at all concerned with this? I've never noticed any phasing but I've also never considered the possibility.
 

Bruce Sokolovic

Fractal Fanatic
never really considered this. So I use two in mine mane preset, but don't have separate fx lines hitting them. one amp block is in the main row, the second below it parallel. signal splits right before them and right after, should I be at all concerned with this? I've never noticed any phasing but I've also never considered the possibility.
Record the same take on separate mono tracks. Zoom in to the sample level and observe if the waves are going in the same direction. If not, either nudge one a few samples so they are and listen back. If you like what you hear after correcting for this, note how many samples its off by and just remember to always advance the earlier track by X number of samples. Truth is if you have never considered it, its not a problem but would be cool to correct if needed.
 
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