# Phase For Mono Dual Subs



## Phillips (Aug 12, 2011)

Hi

I am trying options with my two subs.

Please can someone tell me the correct phase setting.

Thanks in advance

I have attached two graphs.


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## jtalden (Mar 12, 2009)

In regard to the second chart:
The polarity of these 2 SWs is opposite.
the polarity should be reversed on one of them so that they are then the same.
This is not the same as "phase".

After this is corrected:
> If the SWs are equidistant from the LP (within 0.5m) then the phase is going to be good. 

> If not and you have a method of providing different delays for the 2 SWs, or you just want to see exactly how much delay would be needed to align them perfectly, then the REW loopback option can be used to determine how much delay would be needed to put them in phase. The mic needs to be at the LP for the measurements.


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## Phillips (Aug 12, 2011)

jtalden said:


> > In regard to the second chart:
> > The polarity of these 2 SWs is opposite.
> > the polarity should be reversed on one of them so that they are then the same.
> > This is not the same as "phase".
> ...


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## Phillips (Aug 12, 2011)

jtalden said:


> In regard to the second chart:
> The polarity of these 2 SWs is opposite.
> the polarity should be reversed on one of them so that they are then the same.
> This is not the same as "phase".
> ...


Hi i have reset the Velodynes to be running 60hz down.

I have set the left Velodyne as - polarity.

To set the distance settings on both (mono setup) should i set the distance for individual subs against each other, then against both mains?

Thanks in advance


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## jtalden (Mar 12, 2009)

Yes, that is what I recommend.

> First align the SWs in time. This maximizes the output as the SWs are then working together over the whole range. 

[It is not necessarily a requirement for good results however. I would suggest everyone start that way and see if the SWs response is smooth enough for reasonable EQ and if so leave them that way. If not, then either move the SWs to a different positioning or try to offset the timing 1, 2 or 3 ms and see if that helps smooth the response.]

> After the 2 SWs relative timing is set, then the pair is timed to the mains as a mono unit.


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## Phillips (Aug 12, 2011)

> First align the SWs in time. This maximizes the output as the SWs are then working together over the whole range.


Thank you

Do i use a main speaker as a reference to adjust one then adjust the other?

At what stage do i adjust phase, Velodynes have variable phase?



> [It is not necessarily a requirement for good results however. I would suggest everyone start that way and see if the SWs response is smooth enough for reasonable EQ and if so leave them that way. If not, then either move the SWs to a different positioning or try to offset the timing 1, 2 or 3 ms and see if that helps smooth the response.]


When timing two subs against each other looking for smoothest response?



> After the 2 SWs relative timing is set, then the pair is timed to the mains as a mono unit.


With both subs and both mains playing.

Thanks again really appreciate your help, getting a bit confused, too much interruptions.


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## jtalden (Mar 12, 2009)

I just reread the thread and see it added to the confusion by answering generically rather than with your setup in mind. I will try to clarify based on your setup.

[One of your SWs was originally out of polarity relative to the other, but you indicated that that is now corrected.] 

Also above you also indicate the SWs are equal distant from the LP so no relative delay is needed between them. You also indicate the Z9 AVR allows distances to be entered for all the speakers. 

All that is needed then to enter the actual distance for mains and SWs into the Z9 distance settings. The Z9 will provide all the needed delays. 

The only other potential problem is that the current polarity of the 2 SWs is set opposite of what is needed to best work with the mains. To confirm this it is only needed to take two measurements:
> The current SW polarity settings (along with both mains).
> Reverse both SW polarities and measure again.

The SW polarity settings that provide the most SPL support in the XO range is the correct setting.

That is all that is needed for good results. 

The variable phase controls are best left set at zero.

If you want to confirm these are the best settings you can just adjust the SW distances (together) ±4 ft using 1 ft increments to see if there is a better setting. Again the SPL support in the XO range is the factor to watch.


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## Phillips (Aug 12, 2011)

> I just reread the thread and see it added to the confusion by answering generically rather than with your setup in mind. I will try to clarify based on your setup.
> 
> [One of your SWs was originally out of polarity relative to the other, but you indicated that that is now corrected.]


Thanks for your reply

Yes one sub polarity has been changed to minus.



> Also above you also indicate the SWs are equal distant from the LP so no relative delay is needed between them. You also indicate the Z9 AVR allows distances to be entered for all the speakers.
> 
> All that is needed then to enter the actual distance for mains and SWs into the Z9 distance settings. The Z9 will provide all the needed delays.


Yes they sit in between each main. The Z9 with its automatic setup one sub as 7.25 meters so i have setup the same for the other one. Yes all speakers have distance settings, including true stereo subs, if chosen.



> The only other potential problem is that the current polarity of the 2 SWs is set opposite of what is needed to best work with the mains. To confirm this it is only needed to take two measurements:
> > The current SW polarity settings (along with both mains).
> > Reverse both SW polarities and measure again.
> 
> ...


I will try those measurements to confirm

Thanks again


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## Phillips (Aug 12, 2011)

Hi have done some more alterations.

All below are with the mains included.

What seemed to happen was with the polarity changed on the DD15 only, with the mains included there was a huge dip, not in the crossover region though. Also reversed the DD12 (so both reversed) still a huge dip again not in the crossover, very close to just reversing the DD15 only.

I ended up with DD15 polarity reversed and on the Z9 phase Left & Right sub reversed. Yamaha calls it phase but reading last night people are saying in general they are polarity switches effectively on receivers etc.

Now i am confused, any suggestions.

The DDs have variable phase 0 - 180 increments of 15.

Thanks in advance


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## jtalden (Mar 12, 2009)

I am not sure I follow all of this but I will try to comment.

There were only 2 measurements that were really "needed".

> As is, verses with both SW polarities reversed. It sounds like you did that and did not get a significant change at the XO range. That is possible if the SWs are about 90° out of phase compared to the mains. If that is the case, we can adjust the delays a little to correct this. The SW distance setting trials I noted at the end of the last post would have identified and fixed this. I don't know why we would get a big dip in another frequency range however. Did you intend to post the .mdat?

> Do not swap only one SW polarity as we already determined the relative polarities needed for the 2 SWs to work together.

> I recommend that any variable phase control be always left at 0°. They are only helpful if we have no way to adjust distances/delays.


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## Phillips (Aug 12, 2011)

jtalden said:


> I am not sure I follow all of this but I will try to comment.
> 
> There were only 2 measurements that were really "needed".
> 
> ...


I have tried posting the .mdat file but saying "web page unavailable", try later. Did more than two measurements, interesting find was that i had reversed the polarity with the DD15 when it should been with the DD12. I thought that it would have not mattered which one was reversed, but when the mains are bought in, this changes.

What triggered me to look at all options was with the DD15 polarity reversed and with the Z9 sub settings options the best setting was Left & Right reversed, Yamaha calls it Phase when i think it is Polarity. This meant that in theory i was effectively putting the DD15 back to plus polarity and was reversing the DD12s polarity.

I will post the file later to explain

Thanks again


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## jtalden (Mar 12, 2009)

It's best top keep it as simple as possible. Once you have the 2 equidistant SW working together (the same actual polarity as shown by the 2 REW IRs) then there is only 2 options; leave them that way if they reinforce the mains, or change the polarity of both of them if that position best supports the mains. With proper settings, there is no situation where 2 equidistant SWs are better off with one SW working with the reverse polarity of the other.

Any variable position "phase control" is a true "phase control". A variable "phase control" rotates the phase only near the XO point. It is of no real value when we have the ability to adjust the distance/delays properly. It should be left at zero.

Any 2 position switch that is marked "phase" is really a polarity switch. A polarity switch reverses the phase across the entire frequency range by swapping the wires to the driver. The same as swapping the +/- wire connections between the Z9 and the SW or changing polarity in the Z9 settings. 

It is apparently not safe to assume that the polarity markings on a SW switch are always correct for different models and makes of SWs. This is shown by your 2 SWs. They are the same make, but a different model and they are wired differently (unless you inadvertently misconnected your wiring to one of them). Regardless of the source of the issue, the REW IR chart is the final word of what is Positive and what is Negative. There are several models of preamps and amps that reverse the polarity also so when mixing equipment is best confirm that all is well by measuring.

I hope this helps.


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## Phillips (Aug 12, 2011)

> It's best top keep it as simple as possible. Once you have the 2 equidistant SW working together (the same actual polarity as shown by the 2 REW IRs) then there is only 2 options; leave them that way if they reinforce the mains, or change the polarity of both of them if that position best supports the mains. With proper settings, there is no situation where 2 equidistant SWs are better off with one SW working with the reverse polarity of the other.


Please see below zipped mdat files, they have been labelled.

By changing the polarity in the DD12 to minus and leaving the DD15 as positive this gave the best integration, as you will see in the files. You will see the other measurements with the effect.



> Any variable position "phase control" is a true "phase control". A variable "phase control" rotates the phase only near the XO point. It is of no real value when we have the ability to adjust the distance/delays properly. It should be left at zero.


Interesting both the RELs had to have there polarity reversed with my other setup (in the same room). These are on the outside of the speakers (in the corners).



> Any 2 position switch that is marked "phase" is really a polarity switch. A polarity switch reverses the phase across the entire frequency range by swapping the wires to the driver. The same as swapping the +/- wire connections between the Z9 and the SW or changing polarity in the Z9 settings.





> It is apparently not safe to assume that the polarity markings on a SW switch are always correct for different models and makes of SWs. This is shown by your 2 SWs. They are the same make, but a different model and they are wired differently (unless you inadvertently misconnected your wiring to one of them). Regardless of the source of the issue, the REW IR chart is the final word of what is Positive and what is Negative. There are several models of preamps and amps that reverse the polarity also so when mixing equipment is best confirm that all is well by measuring.
> 
> I hope this helps.


Thank you

With the RELs the polarity had to be reversed as well.

I am still not sure how to set the subs and mains IR properly so they match.

Below is two zipped .mdat files, not sure why i can't send together

View attachment DD12 and DD15 60hz Polarity Send 1st half.zip


View attachment DD12 and DD15 60hz Polarity Send 2nd half.zip


Thanks again


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## jtalden (Mar 12, 2009)

I am probably confusing the issue by my definition of "same polarity".

In post 1 you provided the IR chart of the 2 SW separately. I indicated they were opposite polarities and one polarity switch needed to be reversed to be the "same". I then continued to call the polarities the "same" when one switch is reversed from the other. My reference for the "same" is when the REW chart shows they are in fact the same polarity no matter what any switches say.

You are properly keeping track of the switch positions and possibly identifying the SWs settings are the "same" when all the switches are positive. So we may be taking different frames of reference of what is the "same" and what is "opposite".

No matter the terminology we both probably agree that your "DD12 minus DD15 plus" trace is the correct setting. I would identify the SWs as being the same polarity in this measurement (per REW) and also both SWs are the correct polarity for blending with the main speakers.

Does this clarify the issue for you?


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## Phillips (Aug 12, 2011)

> I am probably confusing the issue by my definition of "same polarity".
> 
> In post 1 you provided the IR chart of the 2 SW separately. I indicated they were opposite polarities and one polarity switch needed to be reversed to be the "same". I then continued to call the polarities the "same" when one switch is reversed from the other. My reference for the "same" is when the REW chart shows they are in fact the same polarity no matter what any switches say.
> 
> You are properly keeping track of the switch positions and possibly identifying the SWs settings are the "same" when all the switches are positive. So we may be taking different frames of reference of what is the "same" and what is "opposite".


Understand, "same" means what ever is the correct polarity. 



> No matter the terminology we both probably agree that your "DD12 minus DD15 plus" trace is the correct setting. I would identify the SWs as being the same polarity in this measurement (per REW) and also both SWs are the correct polarity for blending with the main speakers.


Please if you can explain why not just reversing the DD15 didn't present the same result?



> Does this clarify the issue for you?


Yes

Also can you explain how to set the IR to line up at time zero e.g at first biggest peak or dip?

Thanks again


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## jtalden (Mar 12, 2009)

Phillips said:


> Please if you can explain why not just reversing the DD15 didn't present the same result?


> The mains are all installed to a given polarity. They are normally all positive polarity as that is the standard. We don't want to change the mains polarities; we just want to set the 2 SW polarities properly to work in phase with them.

> We then have 4 options for SW polarity settings (the 4 you tested). Only one of the 4 will be correct. 

> We want the 2 SW working to support each other so that rules out 2 of the options. We tested the other 2 situations and chose the SW settings that supports the mains in the XO range rather than the settings that opposed the mains. 

Your test results of "DD12 plus DD15 minus" did not work well. This is because while the SWs were working to support each other, the 2 SWs were working to oppose the mains, i.e., the phase tracking through the XO frequency range was poor.



> Also can you explain how to set the IR to line up at time zero e.g at first biggest peak or dip?


REW automatically set the IRs peaks to zero. Near 0 works well for most all charts. The peak or dip is not normally important.

[If you have a special purpose, it is sometimes helpful to shift them a little. I sometimes shift them a little if I am looking at phase as there is a standard way to present that chart. The chart is still "correct" with the IR at any position. It just may be a harder to read, depending on what you are looking for.]


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## Phillips (Aug 12, 2011)

Thanks

Interesting that with the RELs both had to have reversed polarity.
With the RELs there was no high pass crossover, just ran from the speaker leads with the speakers full range, the way they say is the best.


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