REW Alignment tool - Guides or Manual?

JStewart

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Sorry my question not clear.
Post 169
Were you were saying that when combining the two subs with the alignment tool and align sum it should match the measured two subs graph this is a sign that measurement is ok.

Thanks
Yes. Its a confirmation that nothing has inadvertently been messed up by the user in the process, which can be surprisingly easy to do.

The alignment tool calculations are 100% accurate so when you find the best alignment save the aligned (summed) measurement. Next enter the alignment tool delay into the DSP (minidsp, AVR, whatever). If you now take a measurement of the combined subs and the mic has not been moved and no other settings anywhere have been changed, then the REW actual measurement will match the Alignment tool calculated results, EXACTLY.

When using the .mdat provided and the two measurements I believe to be the measurements for each sub separately and combined them with a 9.5ms delay, the measurement tool Calculated Result did not match a measurement in the .mdat that I assume was an actual measurement of the combined subs also with a 9.5ms delay added to the DSP. Until that can be explained an analysis of the .mdat by others may be invalid insofar as this exercise is concerned.
 

Harrycr

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Yes. Its a confirmation that nothing has inadvertently been messed up by the user in the process, which can be surprisingly easy to do.

The alignment tool calculations are 100% accurate so when you find the best alignment save the aligned (summed) measurement. Next enter the alignment tool delay into the DSP (minidsp, AVR, whatever). If you now take a measurement of the combined subs and the mic has not been moved and no other settings anywhere have been changed, then the REW actual measurement will match the Alignment tool calculated results, EXACTLY.

When using the .mdat provided and the two measurements I believe to be the measurements for each sub separately and combined them with a 9.5ms delay, the measurement tool Calculated Result did not match a measurement in the .mdat that I assume was an actual measurement of the combined subs also with a 9.5ms delay added to the DSP. Until that can be explained an analysis of the .mdat by others may be invalid insofar as this exercise is concerned.
Thank you.
One sub is up front inside left main and center and back one is inside right rear surround (diagonally) behind the couch.
Does this mean that the polarity on the back sub should be reversed?

When measuring combined response with NO delay added and polarity reversed on back sub the graph looks better. Does this mean that go with this setup when phase aligning the 2 subs?

Thanks again
 

JStewart

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Thank you.
One sub is up front inside left main and center and back one is inside right rear surround (diagonally) behind the couch.
Does this mean that the polarity on the back sub should be reversed?

When measuring combined response with NO delay added and polarity reversed on back sub the graph looks better. Does this mean that go with this setup when phase aligning the 2 subs?

Thanks again
If I measures better then it probably a lot closer.
Only way to know for sure is with a measurement of each sub separately with a timing reference and check with alignment tool. Remove any delays or polarity inversion before measuring. Set XO as high as allowed by your gear.

Option B is to Keep changing the delay of one sub in increments of 1ms and re-measuring after each. Tedious but doable.
 

mattel

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Jun 28, 2018
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Agree and you've got a good starting point for EQ.
Ok, I eq’d both subs. There is a substantial improvement in sound quality. Bass is more robust, tighter and really thumps.
Thank you so much!
For sub/main alignment:
measure each sub w/o any delay and with xover
measure FR and FL individually with xover
use center for timing reference
sum sub1+ sub2
sum FR+FL
use alignment tool to align the two summed responses by placing the cursor at the xover freq. and click “align at cursor”

Is this correct?

Thanks again. You have been a great help.
 
Last edited:

JStewart

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Almost. Actually a little easier.

with XO set
with no other DSP modes set that might alter the signal (upmixers, downmixers, etc.)

measure each sub w/o any delay and with xover
These measurements are not needed. The already aligned subs group will be aligned with the mains.

measure FR and FL individually with xover
Yes.

use center for timing reference
Yes

sum sub1+ sub2
Measure the already aligned subs group.

sum FR+FL
Yes

use alignment tool to align the two summed responses by placing the cursor at the xover freq. and click “align at cursor”
I'd recommend using the slider. If you click on the slider you can then use arrow keys to move it which, for me at least, offers more precise movement.

Edit: Link to example https://www.avnirvana.com/posts/46617/
 
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mattel

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Almost. Actually a little easier.

with XO set
with no other DSP modes set that might alter the signal (upmixers, downmixers, etc.)


These measurements are not needed. The already aligned subs group will be aligned with the mains.


Yes.


Yes


Measure the already aligned subs group.


Yes


I'd recommend using the slider. If you click on the slider you can then use arrow keys to move it which, for me at least, offers more precise movement.

Edit: Link to example https://www.avnirvana.com/posts/46617/
Hi, it has been a while since I had a chance to get back to alignment, so I apologize. Emergency eye surgery and not allowed to use my computer for a couple of months, holidays, etc.

I have moved one of my subs so first, I am starting again with trying to align my two subs (HSU's; one ported and the other sealed). I have a Emotiva UMC-1 processor, with a 5.2 setup and minidsp 2x4HD.

Measurements of the subs, mains and center are attached.

This is what I understand to perform 2 Sub alignment:

1. Use R sub base 200Hz XO and L sub base 200Hz XO (measurements with XO set to max =200Hz).
2. Use the slider to find the smoothest response, preferably with the summed output above the individual subs output. Question: while doing this, what should I be looking for from phase response, all 3 lines to converge and overlay each other?
3. Once I find the correct delay, click on align sum.
4. Re-measure both subs with XO's set to max to verify it and the aligned sum measurement are the same.


This is the measurements before delay applied. Except for the dip between ~35-50 Hz. I thought it looked okay.

View attachment 38412

3 sec delay set on slider. Smoother response, however SPL is below individual sub measurements at some frequencies. Not sure what the phase is telling me, though.

View attachment 38409

-16.34 sec delay set on slider. Not as smooth, but good SPL. This seems strange since the right sub is closer to MLP (~7ft. vs. 15.6ft for the left sub. Is the graph indicating the 3 lines are in phase (or close to it, from 40 - 120Hz?

View attachment 38410

I appreciate any help in sorting this out for me. Once I get the subs aligned properly, I will move on to aligning mains with subs.
 

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