# Sub Timing/Phase Adjustment Procedure



## Lumen (May 17, 2014)

First off, I'm not even sure I need to ask the questions that appear below. I think the purpose of time-aligning a sub is to smooth out the frequency response in the crossover region. I also think that auto EQ like Audyssey and Dirac do this for you. *But if using REW, I think it's a manual procedure, correct?*

I know it's onsite somewhere, but *I can't find any info on how to time-align a sub using REW in a multichannel system*. Some threads have suggested using the RTA function in REW, but stop there. Other threads refer to a group-delay method that's been described as complex and non value-added. Rhetorical question: "Who's right?" 

If this has already been covered before, can you please link me to the right thread?

Also, *it would be very helpful to have a birds-eye view of the process*. Just an outline of the major steps would be nice!


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## Wayne A. Pflughaupt (Apr 13, 2006)

BlueRockinLou said:


> First off, I'm not even sure I need to ask the questions that appear below. I think the purpose of time-aligning a sub is to smooth out the frequency response in the crossover region. I also think that auto EQ like Audyssey and Dirac do this for you. *But if using REW, I think it's a manual procedure, correct?*


Yes, time alignment is important to achieve smooth response through the crossover region. Strictly speaking, REW has nothing to do with that. It only shows you the results of the Audyssey or Dirac auto-set up to confirm it’s been done right.




> I know it's onsite somewhere, but *I can't find any info on how to time-align a sub using REW in a multichannel system*. Some threads have suggested using the RTA function in REW, but stop there. Other threads refer to a group-delay method that's been described as complex and non value-added. Rhetorical question: "Who's right?"


RTA, group delay, etc. – these things are only useful or needed if you intend to do the set-up manually. If your equipment has Audyssey or Dirac, use it and you won’t have to worry about any of this. :T

Regards, 
Wayne


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## theJman (Mar 3, 2012)

The term "time align" is generally associated to the adjustments that ensure the output of every speaker and subwoofer reach your ears simultaneously. The most effective way to achieve that manually is to use the 'distance' setting in your AVR or, as you've noted, let the auto EQ system (Audyssey, et al) do the work for you.


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## Lumen (May 17, 2014)

Yes Wayne and Jim, I'll let Dirac handle it for now but there's only one problem. My Emotiva XMC-1 has a fixed house curve, which is too bright for my taste. A user-adjustable firmware version is scheduled to be released "soon". The XMC-1 also has REW PEQ capability, which I've set-up. I swap back and forth depending on source material. 

Dirac does a subjectively better job than REW at recreating a convincing sound field, but it seems bass-shy and treble heavy even after many measurement trials and mic patterns. While I wait for adjustable house curves, I'd like to improve my basic REW skills to get better results. I'm sure the good people here will help me interpret my graphs and keep me on the right path!

Thanks for the input and helping me realize that phase correction, impulse response, and group delay plots are out of my league just yet.


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## Lumen (May 17, 2014)

theJman said:


> The term "time align" is generally associated to the adjustments that ensure the output of every speaker and subwoofer reach your ears simultaneously. The most effective way to achieve that manually is to use the 'distance' setting in your AVR or, as you've noted, let the auto EQ system (Audyssey, et al) do the work for you.


Agreed! Most AVR's accept only distance adjustments these days. To convert the required delay at the crossover frequency requires an understanding of their relationship to wavelength. Here's an example of the calculations needed.


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## theJman (Mar 3, 2012)

BlueRockinLou said:


> My Emotiva XMC-1 has a fixed house curve, which is too bright for my taste. A user-adjustable firmware version is scheduled to be released "soon".


I wouldn't hold my breath if I were you. Emotiva is not what they once were I'm afraid, so it may be a while before you see that.


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## Wayne A. Pflughaupt (Apr 13, 2006)

BlueRockinLou said:


> Yes Wayne and Jim, I'll let Dirac handle it for now but there's only one problem. My Emotiva XMC-1 has a fixed house curve, which is too bright for my taste.


And again, that’s what I don’t like about fixed curves: Every room is different.

Doesn’t the XMC-1 have any kind of user-adjustable tone controls? A simple treble control could take care of that too-bright issue.




BlueRockinLou said:


> The XMC-1 also has REW PEQ capability, which I've set-up.
> 
> Dirac does a subjectively better job than REW at recreating a convincing sound field.


Not sure what this means. REW is merely a measurement platform. :scratch:

Regards, 
Wayne


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## Lumen (May 17, 2014)

theJman said:


> I wouldn't hold my breath if I were you. Emotiva is not what they once were I'm afraid, so it may be a while before you see that.


You may be more right than I want to know ( put emoticon of ostrich-head-in-sand here )! Looking at their XMC-1 forum reveals many unhappy campers who waited a long time past the promised release date of Dirac LE (fixed-curve, restricted version). I had a 60% off certificate, so I bought one on faith. Only Dirac hardware was included. The LE software came later. That was my first breath, now I'm turning blue on my second...

And so, my blue-faced avatar was born LOL!

Sent from my iPhone using HTShack


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## Lumen (May 17, 2014)

*And again ( another bounce *



Wayne A. Pflughaupt said:


> And again, that’s what I don’t like about fixed curves: Every room is different.
> Doesn’t the XMC-1 have any kind of user-adjustable tone controls? A simple treble control could take care of that too-bright issue.


Good point. It has a dual control capability, both parametric style with fixed Q and adjustable level / center frequency. A 1.5dB cut at 3kHz tames the edginess for me. Downside is that these controls are categorized as "trims," so they revert to defaults when the unit's powered-down.



Wayne A. Pflughaupt said:


> Not sure what this means. REW is merely a measurement platform. :scratch: Regards, Wayne


I must be using the wrong terminology. For the current measurement, REW's Equalization Filters Panel shows the coefficients generated for parametric EQ filters (gain, center frequency, and level). Those coefficients can be downloaded into compatible DSP units in REW's Equalizer section. Unfortunately, those values must be manually entered into the XMC-1. It has no download capability right now, but Emotiva has promised a firmware upgrade to fix that (insert emoticon for "sigh" here)!

Sent from my iPhone using HTShack


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## theJman (Mar 3, 2012)

BlueRockinLou said:


> And so, my blue-faced avatar was born LOL!


:rofl2:

An no, it's no coincidental that I chose an emoticon with... a blue face.


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## theJman (Mar 3, 2012)

BlueRockinLou said:


> Good point. It has a dual control capability, both parametric style with fixed Q and adjustable level / center frequency. A 1.5dB cut at 3kHz tames the edginess for me. Downside is that these controls are categorized as "trims," so they revert to defaults when the unit's powered-down.


So every night when you turn it off your trim adjustments are lost?? They're only temporary??? :huh: I wonder how such an obvious flaw ever made it into a shipping product.


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## Lumen (May 17, 2014)

theJman said:


> So every night when you turn it off your trim adjustments are lost, so they're only temporary??? :huh: I wonder how such an obvious flaw ever made it into a shipping product.


Ummm, I _think_ so. I also think I read that in the manual. I only use Dirac on occasion, so that's the only time I check it. I remember having to re-enter it each time. Maybe I just revisited the menu option to check or readjust it. I'll double check to make sure it's not < GASP > operator error. There's been a lot of that floating around lately! :innocent: 

I know for certain that the +/-10dB level trims for center, sub, surround and back speakers return to 0dB (relative to mains) when the XMC-1's power is cycled, and even when inputs are switched! Inconvenient yes. But I need them less as my set-up improves.

In any case, I use the XMC-1's trim control to dial in deep bass rather than upset the sub's calibration by changing its gain setting. Sometimes this changes the balance between low and mid bass, but then I just reign the sub back in. I expect SQ varies with source and program material, but I think I have an underlying speaker setup and DRC problems. Part of the remedy would be to digitally time-align the sub with the mains after it's properly dialed-in. That's why I'd like to learn more about correcting phase.


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## willis7469 (Jan 31, 2014)

Fwiw, my Onkyo doesn't save trims when power cycling unless you do it in the setup menu. This works cause I usually bump my subs for music. My pioneer on the other hand does save trims on the fly. Even when cycled.


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## Lumen (May 17, 2014)

Yup, it's official. Found a setup function which is supposed to lock out (in?) all changes. Made no difference. The tone control settings were lost on power-down. Not complaining, just saying. I haven't explored or learned all the unit's functions yet, so I'm going to give it benefit-of-the-doubt for now. My pre-pro has three layers of lock-out capability, and two different power-cycle strategies involving front and rear switches. Maybe one of those combinations (permutations?) works. Maybe I'll get around to experimenting some day. :nerd: 

onder: Wait, I know! I'll expend energy on multi-channel setup and my REW learning curve instead!

Please understand, I appreciate the help all of you have given me here. I will follow your advice to either program in speaker distances, or let DRC handle it. :wave:


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## Lumen (May 17, 2014)

theJman said:


> So every night when you turn it off your trim adjustments are lost?? They're only temporary??? :huh: I wonder how such an obvious flaw ever made it into a shipping product.


Aaaahhhh-HAH! Found trim retention info (don't you just love user manuals?)! This late post is for my own info, and for those who may need it in the future.

From page-37 of the XMC-1 manual:
"Note: The Level and Tone Trim settings on the Main Zone Menu are temporary trim settings,
and apply only to the current listening session. To make changes to these settings that will
persist after you restart the XMC-1, you will need to change them in the Setup Menu."

...and from page-79: "Trims Adjustments
Use the Trims Adjustment buttons to temporarily adjust the levels on specific sets of speakers.
Note: These Trims are used to make temporary adjustments to speaker levels; for example,
to adjust the levels for a particular movie or disc. Since these settings are intended to be
temporary, they are NOT retained when you switch Inputs or change Speaker Presets, and they
are NOT retained when the XMC-1 is restarted. To make changes to speaker levels which will be
retained, use the Levels settings in the Speakers Preset section of the Setup Menu."

*See page-50 of the manual for the actual steps required.*


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## theJman (Mar 3, 2012)

That makes _much_ more sense. Glad you got it all worked out.


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