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System Delay measurement question

12K views 83 replies 4 participants last post by  Rudy81 
#1 · (Edited)
I need some clarification on how REW is reporting system delay in my setup. My mains are actively crossed 3 way speakers that are set up as follows. A Klipsch RSW-15 (internal amp disconnected and powered separately), a 15" woofer bass bin, and an Oris 150 horn. I took individual delay measurements for each driver and find that the subwoofer measures 50ms, the bass bin 13ms, and the Oris 11.5ms. The bass bin and Oris are physically 12 feet from the measurement (listening) position. The subwoofer is just beihind the bass bin close to the room corner approximately 17' from the listening position.

Why does the subwoofer measure so much farther? Is the correct alignment procedure to delay the bass bin and Oris to match 50ms?
 
#37 ·
John, I think I am finally making some progress. I took my time and followed your measurement example to the letter this time. The results look very promising, at least in terms of being able to recreate your technique.

The first part has been to measure the Oris and DBB (double bass bin) again without any XO, EQ, time delay or other enhancement. I then decided on a 200Hz XO to start. Assumed a 20ms. delay to give myself plenty of adjustment room. The Oris sits on top of the DBB, so I don't expect a huge time difference in the test.

From my interpretation of the results, the crossover (L-R 48dB) set a 204.293 (Ashly restriction) gives me a crossover range of roughly 150-250Hz for the drivers. I originally determined the DBB needed a delay change of 6.524ms to align impulse peaks.

After setting DBB to 13.746 delay and applying the Oris 24.671 IR delay to BOTH plots, I get a nice Impulse with both driver results superimposed at 0.

After unwrapping the phase, and evaluating the results, I decided on a 14.0ms delay for the DBB, giving me a good phase line crossing at 200Hz, with relatively equal phase change over the span of the XO region.

How did I do this time? Any suggestions?

Now I will start working on how to properly work in the passive subwoofer to the newly aligned 'system'. I downloaded HOLMimpulse, but have yet to fire it up....more learning to do there. However, I feel I am getting a good handle on this issue. Thank you so very much for all your help. :D
 

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#43 ·
John, I think I am finally making some progress. I took my time and followed your measurement example to the letter this time. The results look very promising, at least in terms of being able to recreate your technique.

The first part has been to measure the Oris and DBB (double bass bin) again without any XO, EQ, time delay or other enhancement. I then decided on a 200Hz XO to start. Assumed a 20ms. delay to give myself plenty of adjustment room. The Oris sits on top of the DBB, so I don't expect a huge time difference in the test.

From my interpretation of the results, the crossover (L-R 48dB) set a 204.293 (Ashly restriction) gives me a crossover range of roughly 150-250Hz for the drivers. I originally determined the DBB needed a delay change of 6.524ms to align impulse peaks.

After setting DBB to 13.746 delay and applying the Oris 24.671 IR delay to BOTH plots, I get a nice Impulse with both driver results superimposed at 0.

After unwrapping the phase, and evaluating the results, I decided on a 14.0ms delay for the DBB, giving me a good phase line crossing at 200Hz, with relatively equal phase change over the span of the XO region.

How did I do this time? Any suggestions?
:clap: This look good. You found one the possible phase alignments and you have it fine tuned to perfection. You understand the process basics very well. You may be missing some of the fine points, but I am impressed at how fast you picked this up.

Comments:
The alignment you found is the “Time Aligned” alignment. This is the alignment at one of the extremes of the tradeoffs. This one provides:
> The 30-200 Hz range of the DBB to will arrive closely in time to the 400-20k Hz range of the Oris. If those ranges are set to arrive at 0 ms GD then:
> A 200 Hz signal from the Oris will arrive 360° later (5 ms) than the same signal from the DBB.
> The phase at the XO is aligned, but the crossing is at the maximum angle so the phase diverges rapidly as your graph shows. This creates a little chaos in the XO range.

The other extreme alignment would be the “conventional” alignment where the GD is allowed to rotate up gradually to higher values as the freq drops. The phase between the drivers will be closely aligned throughout the XO range that way.

There’s a “compromise” alignment that falls in the middle of these extremes.
 
#38 ·
Here are the files that produced the above results.
 

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#39 ·
Also, in running a 200Hz tone through both driver sets I get a +6dB reading vs. running either Oris or DBB alone. I had originally made sure both drivers were evenly matched in SPL at the XO frequency. If I understand the L-R crossover correctly, this is the result I should expect when the crossover frequency is set up correctly.

I ran this SPL test to confirm that the phase alignment was in fact correct. BTW, this technique rocks!
 
#46 ·
+6 dB at the XO is expected whenever the the 2 signals are in phase. It has nothing to do directly with an L-R filter selection. There are lots of filter choices and alignments that can be chosen to provide good SPL reinforcement in the XO range. The L-R just has the characteristic that it will happen in an electrical XO without needed to adjust the delay in one of the channels.
 
#40 ·
Here are the results of the Oris, DBB and Both for SPL and Phase.
 

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#41 ·
Step and GD for the above results.
 

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#42 ·
Played around with HOLMimpulse and got the results pictured. According to HOLMimpulse, I needed to slightly reduce the time delay on the top end by approximately 4.5ms. That shows to align the time nicely....if I'm using the program correctly.

The phase graphs showed a need to invert the polarity of the sub to get close to the top end polarity at 80Hz.

I am not real clear on the proper use of HOLMimpulse to get the sub and main phased correctly, but hope this is right. Again, please correct me or make suggestions as required.
 

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#50 ·
I can't read this chart - it doesn't look right.

> Expand the IR section back to the default size.
> Start by aligning the DBB and Oris IRs (in the "Options" windows)
> With the IR "Offset Increment" set to a resonable value, use the IR "Offset" controls to move the DBB IR and adjust its Phase. [Always leave the Oris IR aligned at its peak so that its phase is aligned across the range.]
 
#44 ·
After having adjusted the DBB delay for to match the sub phase, I went back to check the top end phase and of course, it was off since I had moved the delay on the DBB. But, now that I new the correct delay for the sub I decided to start again but going the other way. I kept the sub at 0 and adjusted the dBB to match phase.

It turned out that at a nearfield position, the mic does a great job of picking up the subwoofer. Remember, my setup is not a standard subwoofer since each main has it's own passive sub powered by an independent amp.

After setting the sub to DBB phase, I figured out the time on the Oris to be a delay of 21.5ms....it gives me a very good phase match at the 202Hz XO frequency.

So, I think I'm there John. These are the new plots from my 'reverse' process.

There is a big suckout at 60Hz from what I assume is a room mode.

What you do think? Did I get it?
 

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#52 ·
Yes, you got there. :sn:
You found one of the phase aligned timings for both XO's for that channel. It is difficult to see exactly which ones because of the way the IRs are aligned. I would have left a fixed delay in the Oris channel and then adjusted the delay on the DBB to align it and then adjusted the delay on the Sub to align it.

Since your Subs located in the same boxes as the DBB and Oris it’s okay to use the closer mic position. You can set them all alike and then move the mic to the LP just to confirm the channel to channel timing.

With distributed Subs it is be more difficult to align the other channels and create and overall system timing without keeping the first Oris IR as the reference and then adjusting the delays on all the other drivers relative to it. That is why I suggested you set the Oris to high value and a nice even number.

To see the charts for phase and GD along the way you can just subtract out the Oris IR offset in REW from all the drivers. That way the overall picture can be easily reviewed.

It’s also easier if all this is from the LP mic location. Done that way then the other channel drivers can be aligned just by adjusting their delays until they overlay the IR of the same driver on the first channel. The excess delay can then be removed at the end.

If you work through a full setup of different alignments a few times with distributed Subs you would quickly find that that method is much easier.

You don’t have to deal with that with the Subs in with the main speakers.

I haven't reviewed the actual data yet.
 
#45 ·
Here are my final measurments.
:D
 

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#53 ·
The Sub to DBB is about 180° out of phase in this data yo may want toreview this again and see what went wrong. Maybe you just offset the Sub using the wrong value.

Also, the mic postion not being at the LP may produce a very different room response. We did not see the large dip at 60 when you measured at the LP (if I remember correctly).

Please confirm your settings and then provide another set of measurements from the LP.
> Sub
> DBB
> Oris
> All 3 together

Just leave the loopback offsets as measured so that I can offset them myself.
Thanks,
 
#55 ·
Hmmm. Here is a whole new set of sweeps at the LP with no other settings touched. Please let me know what you find. Obviously the 80Hz region has some issues...although at the LP the room resonances are a big factor....
 

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#60 ·
Hmmm. Here is a whole new set of sweeps at the LP with no other settings touched. Please let me know what you find. Obviously the 80Hz region has some issues...although at the LP the room resonances are a big factor....
Side Note:
The Sub and DBB IRs looks like another TW was on that caused a small blip in the IRs of both the Sub and DBB drivers. It was probably on in the Oris also, but it would not be discernable there. The level is very low so the impact did not show up in the SPL and it will not impact the following analysis - just FYI. Possibly the Oris was on at a very low level or the center channel TW was active at a low level?

Now the analysis:
The DBB to Oris is set correctly as we previously found. The Sub is timed incorrectly as it is about 110° out of phase. The SPL confirms we get slightly more SPL support with the Sub inverted, being then about 70° out of phase at the XO. See Charts below:
Text Line Plot Slope Font


Text Line Font Diagram Design


I suspect what caused the confusion was the room mode that disrupted the direct signal phase of the DBB near the XO. This takes some experience to sort out correctly. We are interested in aligning the direct signal phase and not trying to align the phase as distorted by the room effects. To see the direct phase better we can use the "IR Window" feature of REW. If this is done wrong the phase is even more distorted instead of cleaned up. To do it correctly place the Left Window at just before the initial rise of the DBB IR and adjust the Right window down from 500 ms to a value that just cleans up the late arriving room effects without distorting overall general direction/shape of the phase. The direct phase will be smoothly changing without the sudden changes that reflections/modes cause. Don't over do it.

Please also note that the window type of the right window is usually more effective with a Blackman-Harris 4 Window setting for this particular type of phase cleanup. You can see my final window settings in phase chart above.

Note that a narrow windows causes a significant change in SPL that can be misleading at low frequencies. It is better to leave the windows at the default values for SPL charts as I did above.

It is not necessary to unwrap the phase after you get a feel for what is a normal wrap vs what is caused by a room effect. I just left it wrapped for these charts.

I was going to offer and adjustment to correct the alignment, but decided to leave that as at task for you.
 
#49 ·
Will do! Now working on my center channel which is a similar setup but has a 2" compression driver on a P. Audio horn.
 
#51 ·
Decided to play around with HOLMimpulse some other time since I have not time to delve into the nuances.
Center channel was just a little faster to do since I am getting the hang of this.
 

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#54 ·
Looks good.

It will be interesting to see how the phase of the center aligns with the L/R. With different designs they will not match exactly, but it will be good enough to adjust the IRs arrivals so that the LF and MF are aligned at the LP and not worry about the HF.
 
#56 ·
Not sure if there is a problem or not. Just placed the mic back at the nearfield and ran all the tests again. Still looks ok to me.....of course I could be way off.

Here are the untouched results nearfield.
 

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#57 ·
John,
I have a new question for you. My Oris and DBB are always very close in time measurement, but the Sub is way longer than either. Part of that is because it sits behind the DBB Oris combo, but a lot has to do with the seemingly long time the subs frequency takes to bounce off the front wall and be measured. The sub is physically just 3' or so behind the Oris, but gives a much longer signal time.

This issue has been forcing me to delay the DBB and Oris quite a bit. Is it possible to just align in time and phase the Oris DBB combination and just try to phase align them to the sub without the delay? Would that sound ok? Is the time difference going to be a big deal below 80Hz?

I'm just trying to entertain ways to get good phase alignment at the top end without delaying each speaker so much. This is an issue with video lip-syncing.....or at least can cause problems in that area.
 
#62 ·
In an earlier post I mentioned that the excess delay is removed at the end of the process of alignment. In your case with the subs behind the mains. The final sub delay will be 0 ms for one of the 2 subs. The other will be at or near 0 ms also, depending on how symmetrical your setup is. Because you have very steep filters the DBB and Oris will be delayed greater than a physical measurements would suggest. Don't be concerned with that.

In the end we want the direct signal from each driver to arrive at the LP aligned such that the timing and phase is matches the alignment target we selected.
 
#58 ·
Rudy,

John is giving you exemplary help ( so I'm not going to interfere ) .

Most subs ( with heavy cones & relatively weak motors ) suffer from a form of propagation delay ( which is electro-mechanical in origin ). This delay ( typically ) is not predictable and will always place the apparent origin of the soundwave , as emanating from behind the actual physical woofer position .

Personally, I wouldn't synch ( backwards ) to that point of origin . I would simply ( catch the wave ) & get in-phase with it .

:sn:
 
#59 ·
Yes, John has been an outstanding teacher on the subject as you can see by my progress. I am painfully aware that what has been causing major problems in finding a 'cohesive' solution is the inherent problem in getting good readings on a sub woofer.

I asked this question since last night it occurred to me that I should give up trying to time and phase align the main top end to the sub and just keep the top end time and phase aligned....then, phase align the sub to the top end at the XO point. Thus giving me a good response at 80Hz (my XO for sub and main) and good time and phase with the main components.

I have been reading various methods of aligning a sub to the main components. They approach the subject differently, using limited bandwidth to get times of the main vs. sub, using GD, and using excess GD to get a timing reference. But, none seem perfect and as such I'm questioning the usefulness of trying to perfectly time and phase align the three drivers.
 
#63 ·
John,
Those graphs really help me understand your comments. Very clear to see what you mean and I now understand your comment on the sub phase issue.

I suspect that the problem driver has been the sub all along due to IR and room modes at the LP.

I am going to get on this in a few minutes and start over for both practice and to have a known start point vs. trying to manipulate data I worked on yesterday.

Although a trying experience for you, I have really increased my knowledge on the subject and am very appreciative of your time. I wish I knew a of a lot more on the subject.
 
#65 · (Edited)
Since a picture is worth a thousand words, here is the setup.

Main L Channel composed of independent sub, DBB and Oris horn. (Main R channel is identical)
Center Channel composed of independent sub, DBB and 2" compression driver horn. (DBB has different 15" woofers capable of higher extension)
Last picture is of the three front channels from the LP.

Note: Although the three subs look stock, they are not. The internal amp and crossover has been disconnected. Each sub is individually controlled by a dedicated XO channel and dedicated amp channel.

As you can see the subs are physically close to the other components, particularly the center channel. The sub time readings are a real pain to process properly. That is why much of this did not make much sense from a physical viewpoint.
 

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#67 ·
Since a picture is worth a thousand words, here is the setup.

Main L Channel composed of independent sub, DBB and Oris horn. (Main R channel is identical)
Center Channel composed of independent sub, DBB and 2" compression driver horn. (DBB has different 15" woofers capable of higher extension)
Last picture is of the three front channels from the LP.

As you can see the subs are physically close to the other components, particularly the center channel. The sub time readings are a real pain to process properly. That is why much of this did not make much sense from a physical viewpoint.
Nice setup!

I don't understand your concern with Sub timing. Can you explain?

It is no doubt the separation between the Sub and DBB that results in the deep cancellation at 60 Hz when using the close mic position. Stick with the mic at the LP for that XO alignment.

Side Comment:
With the 80 Hz XO, 3 equal subs in separate boxes, and delay capabilities on all the subs it would be advantageous to run the subs as mono. Their positions could be distributed more freely (although its probably not necessary) and the resulting EQ would be much easier/smoother and equal for all channels. Go ahead and with the present plan, but keep that in mind for a future evaluation. I am pretty sure you will prefer it.
If you do it:
> Set the sub delays for equal arrival times.
> Change positions of the subs if needed to get a reasonably smooth SPL.
> Set an EQ for the subs.
> Set your target alignment for one channel.
> Match the IR arrivals of the drivers on other channels.
> Final EQ for each channel.
> Pull out any excess delay.
 
#70 ·
RE Mono SWs:

I wrote the last bit above before the rest and didn't change it once I saw that you have the 9.9 Pre/Pro.

It is of course much easier to let the 9.9 manage the sub XO. That way you will only have the single sub output for the input to the DCX. The signal can be sent to 3 outputs for separate delays as needed. A single EQ can just be set on the input channel.

The 9.9 XO will apply an LR-24 LPF and a B-12 HPF to create the XO. There will be no problem with that, but you can augment it if you like by adding additional LPF and/or HPFs in the DCX/Ashly.

If you are planning to run Audyssey that will change all the distances/delays in the Pre/Pro and make any initial manual EQ's a waste of time. You can use Audyssey for EQ, but the timing process gets even more confusing.
 
#79 ·
If you are planning to run Audyssey that will change all the distances/delays in the Pre/Pro and make any initial manual EQ's a waste of time. You can use Audyssey for EQ, but the timing process gets even more confusing.
Your comment on Audyssey has had me wondering if using Audyssey will invalidate all the work on time and phase alignment. I have been researching the issue and feel that changes made by the Integra PRIOR to the XO, should not change or affect the driver phase and timing settings. This, if I understand this correctly, is what is happening when the Audyssey modified signal is sent from the Integra to the Ashly to apply the XO.

The signal outputs from the Ashly to the amps and then the speakers.

This is my understanding based on this article.

On a side note, your idea to run the subs in mono was brilliant. Although I was only able to get the two corner RSW subs in phase and working together, they work great for the L, C and R speakers. The extra RSW is now just a spare.
 
#71 ·
Lots of stuff to consider. I was using direct mode in the 9.9 to avoid any Audyssey issues. I'm not sure if the distances in the 9.9 also play a role in direct mode, but they were set at about 14 feet in any event.

Yes, something just does not jive with the delay on the RSW-15 subs.

I decided to implement your mono sub idea...and yes, it turned out great. It certainly sounds good, but I was never able to integrate the center sub properly. The two corner subs were almost perfectly in phase. The center sub located next to the center DBB was another story. I could not get it to match the other two subs. I then decided to just use the two corner subs and save myself more headaches....certainly plenty of output with just the two.

So, the way it works now is that all three front channels feed the two corner RSW-15 subs. The Folded Horn SPUD subs do LFE duty so I had checked all the subs to ensure they would not cancel each other out. I lucked out and only needed to reverse the polarity in the SPUDS to get decent phase agreement between subs.

From there, setting the main and center DBBs and HF sections was quick. I think in the last few days I have done that 100 times.

The reason I went to all this trouble is that I needed to align each individual speaker with the three main driver sets. Then, working as one speaker, I can run Audyssey Pro like anyone else does with normal speakers.

I had assumed that when Audyssey makes changes to the entire system it will of course have an effect on the main three channels if it makes any changes in the XO regions....but then isn't that true of all speakers?
 
#73 ·
Lots to consider – I guess!! I didn‘t realize that the system was so complicated – 7 channels, Audyssey Pro, folded horns for LFE? I may be out of my league in helping you align all of this. It's safe to say that you are not with the minimalistic crowd. I’m sorry I didn’t catch on sooner. I understood we were talking 3 channels and assumed some of the listed equipment must be used in other setups.

It is tough to know where to start.
I do see you have pro amps and read that some now have delay/XO/EQ capabilities built in. Is the CC sub P-amp the source of the extra delay?

I am only now starting to see why you were focused on a 3-way setup for the fronts as the LFE was to be separate. That does probably make sense considering the combination of LF equipment.

On the negative side (I’m a pessimist) I would expect the phase rotation for the Subs vs the folded horns to be different. If a signal was common to both then there may be a phase problem at some freqs. The LFE is maybe/probably always a unique signal and if so, it is probably no issue. [Just thinking out loud.]

As I said, I probably don’t have enough experience to sort all this out with only peep hole view to the reality of it. You seem to have absorbed most all the concepts and methods I use so maybe you can fit it all together.

It is getting very confusing for me to understand the exact situation and questions in the proper context. I think most of my comment above were okay, but without proper context it is difficult to be sure. I will still try to answer questions if you like, but please take my comments cautiously.
 
#72 ·
BTW, when I was struggling with the reported IR timing on the subs, I checked and re-checked the DCX and Ashly. All 3 subs report very long LP times vs. the DBB and HF. The DBB and HF all come in around 12-14ms. at the LP, although the DCX controlled the CC at the time. The sub on the DCX and the subs on the Ashly were all very long in the 20-30ms. range.

It just seems that the long wavelength and limited FR of the subs leads to inaccurate IR readings. I have read several articles now that discuss this issue and all point to those two items as the source of the difficulty.

The good news is that I just ran a basic sound check on the main channels in stereo to see where I stand and it sounded very good. Now a little more tweaking and hopefully I will be done with this.

I did change the CC XO to LR 24dB in order to get a more gentle transition between the DBB and the HF horn. I quickly tested a movie with good CC dialog and liked what I heard. I got a more 'full' vocal in conversation. The HF driver is the weak point right now, but that upgrade I'll leave for another day.
 
#76 ·
BTW, when I was struggling with the reported IR timing on the subs, I checked and re-checked the DCX and Ashly. All 3 subs report very long LP times vs. the DBB and HF. The DBB and HF all come in around 12-14ms. at the LP, although the DCX controlled the CC at the time. The sub on the DCX and the subs on the Ashly were all very long in the 20-30ms. range.

While I still can't relate to a 30 ms delay being an issue for lip synch from my limited experience, I do remember something that might help you with lip synch.

With my longer delay setups I did have a minor problem on some material input sources. I adjusted the speaker distances to the maximum possible in the 9.8 (30 ft) on all channels). This resolved the problem. My theory was that the 9.8 may consider speaker distance in its calculation of lip synch. It seemed to work, but I never actually measured the impact on delays to measure is effect. You may want to try it. There are also manual lip synch setting for the various inputs as well. I usually just turn on the automatic one.

Note that, the audio signal timing is unchanged by 5 ft settings for all channels or 30 ft for all channels. The delay for the closest channel is 0 ms and the offsets needed for other channels are adjusted accordingly. I think that the large speaker distance settings just increases the delay on the video signal accordingly assuming that feature is turned on.
 
#74 · (Edited)
Yes, some pro amps have those capabilities and I checked all that as well.

Yes, it is a complicated system, but I rely on Audyssey Pro to handle the nuances between the 7 channels and the .1 LFE.

All our discussion is solely directed at getting the L, C, and R channels to each act as one 'speaker'. The various drivers and subs just give me the option of having a truly full range speaker. In a word, I was trying to 'voice' each main speaker.

I think all your comments and ideas have been right on.
 
#75 ·
After two days of working on this and implementation of your mono sub idea, I was confident enough to see how Audyssey would 'see' the speakers and handle the EQ. Amazingly, there were no obvious problems with the L, C, and R speakers as they are set up. The two RSW-15s in the corner really put out a lot of LF! Although I reduced the dB input a bit, they still crank LF as you can see in the Audyssey plot.

I am going to take some time to listen to the system and see how it sounds as it is. Some day when I'm bored I'll hook everything up again and see how the system phase and time has changed at the LP in the current setup.

Great learning lesson. I hope I passed Time and Phase 101....

Thank you for your help, I can't say it enough.
 

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#78 ·
This evening got to test various movie material. Music, and mostly dialog as well as action. First impression is that the LFE subs and the RSW-15s are definitely in phase. Huge amounts of very clean and authoritative bass.

The other issue was lipsync was right on the money on all dialog movies.

So far so good. The real test will be pure 2 channel listening of my favorite songs. I did listen to some multi channel SACD and they sounded very, very good. Again, great bass reinforcement. Hopefully this will work out as I had hoped.

An unexpected, but very worthwhile, change was to go with mono subs. What a great idea John. Now I get really well balanced LF from all three main channels. The omnidirectional nature of LF lends itself well to this setup.

So far I'm very pleased with the results. More tomorrow.
 
#81 ·
John, ok. I think we are on the same page. You are correct, the RSW-15 subs are acting as true LF woofers for the L, C & R speakers. My dual tapped horn subs are the once connected to the LFE output.

You are correct that Audyssey will change the delay of the speakers based on its calculations.

BTW, the article I mentioned in the last post is an excellent review of the same principles you discuss in your post. In my case, it helped to clarify what you discussed. The three part article is very good and has several examples on implementation of the procedure.

I am currently going through the HOLMimpulse help file to learn how to use it. I want to see how it works on the LP and the sub phase measurements.
 
#82 ·
John, I'm still spending time planning my next journey into measuring everything again. I am not totally clear on the procedure to measure the RSW-15 sub after completing the time and phase alignment of the DBB and Oris. Is the below sequence correct?

Assume I start with a 20ms added delay.
Align the Oris and DBB with REW. Assume DBB is moves back 1ms.
Move the mic to the LP
Switch to HOLMimpulse
Do I start by measuring the Oris again with the 20ms added delay and the DBB with the 19ms delay?
Measure RSW-15 with 20ms added delay?
align phase of RSW-15 to DBB.
Subtract the smallest change from all drivers so that smallest change (Likely the RSW-15) will have 0 delay?

My point is that I'm having trouble planning the exact sequence of events when transitioning the measuring the RSW-15.
 
#83 ·
...
> Assume I start with a 20ms added delay.
Okay

> Align the Oris and DBB with REW. Assume DBB is moves back 1ms.
DBB delay reduced to 19 ms - okay

> Move the mic to the LP
Okay [You could just do the whole process from the LP, i.e., the above steps.]

> Switch to HOLMimpulse
Just use REW as you have a reasonably clean IR measurement and are experienced with the REW process. [HolmImpulse is recommended more as a learning experience to better understand how phase changes with IR location. If you are familiar with HolmImpulse it is easier and quicker to align the phase of drivers because the controls it provides suit this alignment process better.]

> Do I start by measuring the Oris again with the 20ms added delay and the DBB with the 19ms delay?
Yes - Leave the delays as set above (Oris 20 ms and DBB 19 ms) you should mute the Oris though and just measure the DBB again at the LP.

> Measure RSW-15 with 20ms added delay?
Yes, start there or at 19 ms, but then adjust RSW-15 delay to align its initial IR rise with the initial rise of the DBB IR.

> align phase of RSW-15 to DBB.
Yes - fine tune RSW-15 delay for final phase alignment.

> Subtract the smallest change from all drivers so that smallest change (Likely the RSW-15) will have 0 delay?
Yes, the smallest delay will depend on which alignment you chose for the 2 XOs. You are correct that it is likely that it will be the RSW-15 considering it is placed several feet further away. So if the final RSW-15 delay is found at 12 ms then 12 ms can be removed from all 3 delays. The final delays would be RSW-15 = 0 ms, DBB = 7 ms and Oris = 8 ms.

---------------

[Note: The 20 ms delay was intended to provide a safe cushion for upcoming timing of the other mains and the SW/LFE channel. I now understand that you are going to leave that final channel to channel adjustment for Audyssey to set via the pre-pro distances. That is the correct thing to do when using Audyssey. It just means there will just be more excess delay to remove in that last step.]
 
#84 ·
Thank you sir. In fact I did as you suggested earlier today. Ran everything from the LP and REW worked very well indeed.

System is up and running and have not noticed any issues in sound, Audyssey measurements or full range sweeps.

Now to enjoy...finally!

:R
 
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