Cab Lab 3 Converting

R

RockerAlex

Inspired
I've noticed you can now apply "Min Phase" and "Auto Trim" to the conversion process ... did Cab Lab 2 have any of those options ticked by default and is there any benefit to adding these in the conversion process?
 
Cliff, could you please explain what does exactly Min Phase and Auto Trim to a raw IR ?

Thank you.
 
Clive said:
Cliff, could you please explain what does exactly Min Phase and Auto Trim to a raw IR ?

Thank you.
Click to expand...

Minimum Phase Transform basically throws away any of the original phase information and instead derives it from the magnitude response. Basically it will make your IR have the minimal delay time possible, the trade-off is you throw away the captured phase information (but I guess use your ears see if that matters to you).
If you are mixing IRs, you should probably choose this option to avoid the "phaseyness" that can result from combining IRs with different times of arrival.

Auto Trim will delete any leading silence from the IR - not the same as MPT, as this doesn't guarantee that the resulting IR will be minimum phase.
 
Thank you AlbertA for your answer.

AlbertA said:
Minimum Phase Transform basically throws away any of the original phase information and instead derives it from the magnitude response. Basically it will make your IR have the minimal delay time possible
Click to expand...

This is where I'm confused. I thought this was what did Auto trim and that's why I don't understand the difference between the two.


AlbertA said:
If you are mixing IRs, you should probably choose this option to avoid the "phaseyness" that can result from combining IRs with different times of arrival.
Click to expand...

Yes, this is what I understood.


AlbertA said:
Auto Trim will delete any leading silence from the IR - not the same as MPT, as this doesn't guarantee that the resulting IR will be minimum phase.
Click to expand...

Imagine I have a 100 ms IR with 5ms of silence at the very beginning. If I choose Auto trim, these 5ms will be removed, OK but will my IR be 95 ms length or will it be lengthened to 100ms and how in this case (stretching it, adding 5ms of silence in the end...) ?
 
Clive said:
This is where I'm confused. I thought this was what did Auto trim and that's why I don't understand the difference between the two.
Click to expand...

Auto-trim does not throw away any phase information. MPT does. In mathematical terms MPT is the Hilbert Transform of the log of the magnitude response (hence the "throws ways the phase response")

Imagine I have a 100 ms IR with 5ms of silence at the very beginning. If I choose Auto trim, these 5ms will be removed, OK but will my IR be 95 ms length or will it be lengthened to 100ms and how in this case (stretching it, adding 5ms of silence in the end...) ?
Click to expand...
Your IR will contain 95ms of actual information (well assuming it actually contains information beyond 25ms but that's besides the point. I don't know what CabLab does internally but I highly doubt there will be any "stretch".
 
I'm still confused on why you would check 'Auto Trim' and why you would or wouldn't check 'Min Phase'. For really dumb people like me, are there basic rules or circumstances of choosing or not choosing either of those options? I will be eventually mixing ir's, so would check Min Phase, correct?
Sorry, I know it's been answered but I still have no clue if I should choose Auto-Trim or not.
As always, Thank you soo much!
 
AlbertA said:
Auto-trim does not throw away any phase information. MPT does. In mathematical terms MPT is the Hilbert Transform of the log of the magnitude response (hence the "throws ways the phase response")
Click to expand...

OK, so if I understand you correctly, to apply a minimum phase transform to a raw IR, CabLab :
-takes the raw IR and keeps the magnitude response,
-computes a new phase response with the Hilbert transform of the log of the magnitude response.

Is it that ?

Two more questions :

1/ When Cab-Lab applies a minimum phase transform to a raw IR, has the new IR the same length as the initial raw IR ?

2/ When Cab-Lab applies a minimum phase transform to a raw IR, is there any silence at the very beginning of this new IR ?


Thanks.
 
Don't know about others for sure , Kevin at Ownhammer said don't auto trim his IR's or it will degrade the sound . I would assume all pro Ir's would already have the maximum allowable trimming without losing quality ! I have deal with some IR's in the past that had too much lead time therefore creating latency , this is where the auto trim would come into play !
 
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