# Trying to get my crossover setup for a 2 way



## NBPk402 (Feb 21, 2012)

Obviously my setup needs some work... I was thinking of running the Auto EQ in REW and loading it into the minidsps, but I don't know what I should be setting the target settings at... This is what I have the minidsp set for currently... All measurements are from the MLP.

What is my next step?


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## jtalden (Mar 12, 2009)

Before setting EQ or running any auto setup for SW-mains delays/distance settings, it is best to first confirm the 500Hz XO driver delays are optimized. If the XO delay timing between 2 drivers is correct there will be the smoothest handoff between them. That will minimize the EQ necessary in the XO frequency range, and will also help to improve sound stage and imaging. 

After all the delays/distances are set correctly then EQ can be done. 

There are various ways to set the 500Hz driver delays and the process somewhat depends on the measurement setup. it is best to use a XLR mic and utilize REW loopback timing, but good results can be obtained with a USB mic as well. It just requires a different method.

If you want to do this before moving to EQ I can provide some direction if needed.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Before setting EQ or running any auto setup for SW-mains delays/distance settings, it is best to first confirm the 500Hz XO driver delays are optimized. If the XO delay timing between 2 drivers is correct there will be the smoothest handoff between them. That will minimize the EQ necessary in the XO frequency range, and will also help to improve sound stage and imaging.
> 
> After all the delays/distances are set correctly then EQ can be done.
> 
> ...


Hi,
Thanks, I am using the UM1k USB mic... How do i set the 500Hz delays? Also do I need to do the measurements nearfield, or is MLP ok?


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## jtalden (Mar 12, 2009)

If your horns are directly on top of the woofers then I would recommend measurements at 1.5-2.5m. It may be possible to use LP measurements, but at 500 Hz there may be significant reflections in the response that that make it more difficult to interpret the charts correctly. Estimate a point approx midway between the center of the horn mouth and the center of the woofer. The line from the MLP to that point is the direct sound axis. If we move the mic to ~2m distant on that direct sound axis the measurements will usually be much easier to accurately interpret. The mic placement doesn't have to be highly accurate - just eyeball it. 

There is no reason not to try the mic at MLP first to see how that works if you prefer. 

Using a USB mic is a little more work, but we will try to be as efficient as possible...
> Measure the distance from the MLP to woofer dust cap.
> Measure the distance between the MLP and throat of the horn, i.e., the connection point between the horn and the compression driver. 
[Try to get these distances measured within ±2-3 inches.]
> The difference between these 2 distances is an estimate of the delay needed for the a driver.
[If the horn distance is 0.5m larger than the woofer distance then we would enter a 1.45ms delay for the woofer into the MiniDSP (1000ms * 0.5m / 345m = 1.45ms).]
> We then measure one speaker with the mic at LP (or ~2m on the listening axis). Leave the XO and EQ active as you show above. Set REW measurements to sweep 50-20k Hz
- Sweep measure the woofer 
- Sweep measure the horn 
- Sweep measure the woofer+horn (both together)

This will define the starting point. If you post this .mdat file I will be able to see if the starting point is okay. Depending on the findings we may be able to reduce the following measurements somewhat, but I show below what may be needed to complete the job.

Next:
1. Increase the woofer delay 0.2ms
2. measure the woofer+horn.
Repeat 4 more times.
Next: (starting with the delay at the original value.
1. Decrease the woofer delay 0.2ms
2. measure the woofer+horn.
Repeat 4 more times.

The delay nearest the starting delay that provides the most SPL support through XO range is very likely best delay setting. It is usually easiest to make this judgment by using 1/6 octave smoothing for the traces. 

After that initial series we can decide if we want to fine tune any closer than that. Also by measuring individual drivers again with the new delay setting I can confirm that all is well. The same delay setting will also be correct for the other speaker. No need to test it if reflections haven't muddled the measurements. I usually just confirm the setting works properly there with a measurement of the individual drivers and both together.

Its a bit of work, but I think it will be a noticeable improvement in sound quality.


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## NBPk402 (Feb 21, 2012)

Thanks, I should be able to get this done either tonight or Tuesday. :T


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## NBPk402 (Feb 21, 2012)

Note for self... Woofer to front of woofer 60", Horn driver to front of horn 32.1 + 17" to front of bass bin". MLP for center 11'. MLP for Left 11' 10". MLP to right 12'4".


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## NBPk402 (Feb 21, 2012)

This is for the horns...


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## NBPk402 (Feb 21, 2012)

This one is for the bass bins... Left, Center, Right.


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## NBPk402 (Feb 21, 2012)

Subs... Front, Rear.

Data file for all above charts in one.


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## NBPk402 (Feb 21, 2012)

horns with old polarity


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## NBPk402 (Feb 21, 2012)

horns (with old horn polarity) and bass bins together (bass driver polarity unchanged from first bass bin test)...


Data file for horns (old polarity), and bass bins... http://www.mediafire.com/download/q4iv8vv6jx65tri/111114_bass_bins_with_old_horn_polarity.mdat


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## NBPk402 (Feb 21, 2012)

All of the above plots are with the minidsp crossovers in place with the above settings.


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## jtalden (Mar 12, 2009)

Lots of measurements. I am a bit confused. Okay, more than a bit.

I opened the Post 7 and Post 12 .mdat files, but I think there must be 1 or 2 others that were not posted. I didn't find the BB measurements I needed.

Rather than me trying to pull out and combine the files to find what is needed, maybe you can do that. Provide 1 file with just the 3 measurements that I asked for. Let's pick the left speaker and the "New" (Neg.) polarity for the H. Provide a file with just; BB, H, BB+H. 

I noticed that you have the mic calibration file loaded as both the mic cal and the soundcard file. You will want to remove it from preferences/soundcard so it doesn't show up in any future measurements. The measurements you made are okay as I will just manually remove the soundcard cal from each measurement in the measurement panel. There is no need for new measurements at this time. 

I didn't clearly follow you notes on distances. What different in distance did you find for the driver distances (BB behind H by 10.9"?) and what delay for which driver was entered as a result? it appears the delay setting used may have been good as a starting point. 

Was the mic at the MLP? The phase data is okay in these measurements so the mic was okay at that location.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Lots of measurements. I am a bit confused. Okay, more than a bit.
> 
> I opened the Post 7 and Post 12 .mdat files, but I think there must be 1 or 2 others that were not posted. I didn't find the BB measurements I needed.
> 
> ...


Ok...

I will start over with the whole setup as it appears that my BB are out of phase with the rest of my system. My horn sits on top of the bass bin but it sits back 17" from the face of the BB, which is why I included that spec. Which puts them much closer to each other in distance for delay now.


Left BB with correct phase...
Left Horn with correct phase only...
Left BB with Horn correct phase...

Data file... http://www.mediafire.com/download/7h6d8z511oc7od7/Left_channel_with_correct_phase.mdat


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## NBPk402 (Feb 21, 2012)

Looking at the new plot... I am wondering if i should raise the gain on the Horns a bit.


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## jtalden (Mar 12, 2009)

Thanks for the file.
You made a good choice on polarities. It is functionally the same as what I requested in terms of phase tracking so it worked out well.

Since you didn't clarify the requested distance/delay information I will assume that there was 0ms delay in the MiniDSP for both drivers.

We are fortunate that this delay worked very well for us. We are also fortunate that it was very easy to accurately determine the current relative delay by inspecting the IRs of the BB and H measurements. This is not always easy to do. We are also fortunate that the direct sound phase tracking is relatively easy to determine as the reflections were not a major problem. This means there is no need for additional experimental delay measurements. I was able to identify the ideal setting. It is very close to the 0ms delay you now have set. To be ideal the BB delay needs to reduced by 0.20ms. Since it is at 0ms and can't be reduced, we instead will increase the H delay by 0.20ms.

This change is relatively trivial. it amounts to only a shift of 36° at 500 Hz. This is not enough to have a significant impact on the SPL. It does represents a fine tuning of the phase tracking through the XO range. 

The following charts may be if interest:
The chart below shows the XO range extends from about 350Hz to 1kHz for a 25dB reduction. This is the XO range we are most concerned with. It also shows there is currently good SPL support in that range.








The chart below is similar, but includes the 0.20ms delay adjustment. There is no significant impact to SPL.








The chart below shows current relative IR positioning. Because of the shape of these curves I was able determine this alignment accurately.








The chart below shows the current phase tracking. It is reasonably clear in the 350-1k range and I am able to identify the direct sound phase tracking even beyond that range. I placed the dotted lines to show the relative phase without the impact of reflections. There is only minor divergence of the lines. This is very good tracking.








The chart below shows the same information with the 0.20ms delay adjustment. The direct sound phase of the BB and H now fall directly on top of each other throughout the 350-1k range.








The chart below shows the same information, but now there is a time window applied and the phase is unwrapped to help clean up the chart so that it is more easy to interpret for those not used to reading them. This chart better shows that there is a slightly increasing divergence below 350Hz. The top end is directly tracking up to 1200Hz where the BB then rises sharply departing from the H. [Note that, there is a reflection at 1200Hz that causes a 360° drop to the trace line that is misleading on the chart. My description is the correct interpretation.] Phase tracking at the extremes of the XO range does not get better than this with IIR filters unless there is a lot of fine tuning using lower XO slopes. This is the best that can be done in this situation.








So:
You can now; set the MiniDSP delay the same for the FR and CC, adjust the TW level (as you mentioned) to minimize the EQ load, and then run Audyssey if that is you plan. Audyssey will adjust the rest of the delays by setting speaker distances. You may want to confirm the proper SPL support of the SW-BB XO range to assure that the SW delay was done correctly.

Just an additional thought:
I don't completely understand you setup and constraints, but...
You mentioned the mouth of the H is 17" back from the mouth of the BB. If that is the case then the H is strongly reflecting off the top of the BB box. This would be expected to cause strong comb filtering in the H frequencies. I don't know how much the sound quality would be impacted. I only mention it in case it is easy to slide the H forward 17" to place it flush with the mouth of the BB. That would improve the situation. Of course the MiniDSP H delay would need to be increased +1.25ms to account for the 17" H shift. 
It's just a thought in case it happens to be a practical change.


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## NBPk402 (Feb 21, 2012)

Just to clarify...

1: My HF has a 2 ms delay the bass bins have 0 ms delay 
2: I can easily move the horn forward to be close to the front edge of the BB... I will do that if you wish. :T
3. Should i raise the gain on the horns at all to get a higher match at the 500Hz crossover?
4: I have first reflection panels on the side walls... They are 4" of Roxul R80 2' x 4' panels.

My intent is to try and get the front 3 channels sounding as good as they can with out Audyssey, so i can listen critically in stereo mode when I like, and then have Audyssey when I am watching movies.

Still reading through the rest of your comments, but i wanted to address your 2 comments first.


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## NBPk402 (Feb 21, 2012)

Left channel after Horn Gain raised, and also after moving the horn forward with gain raised already.



Here is my Data file after raising the horn gain, and moving the Horn forward... http://www.mediafire.com/download/a..._Left_gain_raised_and_horn_moved_forward.mdat


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## jtalden (Mar 12, 2009)

Thank for the additional data.

I only see a minor improvement in HF SPL variability with the H moved 17" forward. I was thinking that it may be more visible in the data, but it looks much the same. I would be surprised if you can hear a sound quality difference base on this data. Still, if it were my system I would leave them forward enough that the H doesn't see/dump on the top of the BB. Maybe it is better to take the conservative choice when the evidence isn't clear?

I like the +5dB shift to the H level. It will make the EQ filters more balanced. It is probably not a real issue as EQ boost/cut has the same effect just as Wayne has highlighted. It may reduce the number of filters needed if we were using a PEQ filter box however. I don't expect Audyssey to care one way or another as long as the boost/cut range is not exceeded or it calculation limits are not exceeded for filtering. The new H level is very appropriate and eases the filter burden.

For my understanding please clarify. See below. Was the "initial" H delay 0.5ms? So the "new" setting changed to 0.70ms? Then, with the 17" H shift, the H delay was set +1.25ms to 1.95ms? I ask because there is apparently a significant change in the phase tracking between my predicted phase tracking and your latest BB+H measurements. Maybe the delay change did not take?

I sometimes get confused on direction of a change that is needed so it is good if we are extremely clear on delay settings for measurements so I can spot mistakes. 

Please clarify the following:
BB Delay = 0ms (for all measurements)?
H "Initial" Delay = ??ms
H "New" Delay = ??ms
H "17in shift toward mic" Delay = ??ms 

You can also run the 3 FL measurements again and I will confirm that the Final delay provide the expected result.

Thanks.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Thank for the additional data.
> 
> I only see a minor improvement in HF SPL variability with the H moved 17" forward. I was thinking that it may be more visible in the data, but it looks much the same. I would be surprised if you can hear a sound quality difference base on this data. Still, if it were my system I would leave them forward enough that the H doesn't see/dump on the top of the BB. Maybe it is better to take the conservative choice when the evidence isn't clear?
> 
> ...


The initial delay was 2ms (my mistake as I mis-read it), and I have not yet changed it.

BB delay= 0ms
H initial delay 2 ms
H new delay still 2 ms
H 17" shift toward mic delay still 2 ms

I will rerun with all 3 front speakers (need to move all the Horns up first).

BTW... Just wanted to let you know all my measurements are firing through a SeymourAV XD screen if that matters at all. :T


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## NBPk402 (Feb 21, 2012)

Here are the new measurements for today...
These are with all the horns moved forward
All horns had the gain raised (as close as I could get them to matching per the graphs)
All horns are still on the 2ms delay
All bass bins are still on 0 ms delay

Link to data file... http://www.mediafire.com/download/7...horns_moved_forward_2ms_horn_delay_230pm.mdat
Data file has each horn individually tested, each bass bin individually tested, and each horn/BB individually tested.

All measurements are from the MLP.

Graphs have horn only first, then BB, then complete channels


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## jtalden (Mar 12, 2009)

ellisr63 said:


> The initial delay was 2ms (my mistake as I mis-read it), and I have not yet changed it.
> 
> BB delay= 0ms
> H initial delay 2 ms
> ...


The screen will not impact the delay required for good phase tracking.

I will not analyze the measurements in Post 21. If I did, I should come up with the same needed delay for the H (2.0ms initial + 0.2ms correction + 1.25ms for the 17" H shift = 3.45ms H delay). I said it was "easy", but that was relative reference. It still took me several hours to do the work the first time. I will not repeat the work unless there is a demonstrated problem with the recommendation. So it is best measure with a 3.45 H delay setting to confirm that actual results meets the expected results.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> The screen will not impact the delay required for good phase tracking.
> 
> I will not analyze the measurements in Post 21. If I did, I should come up with the same needed delay for the H (2.0ms initial + 0.2ms correction + 1.25ms for the 17" H shift = 3.45ms H delay). I said it was "easy", but that was relative reference. It still took me several hours to do the work the first time. I will not repeat the work unless there is a demonstrated problem with the recommendation. So it is best measure with a 3.45 H delay setting to confirm that actual results meets the expected results.


So I should set my delay to 3.45ms for the horn or for the bass bin? The bass bin has a 60" horn length where as the horn has a 32.1". Just trying to make sure what I need to do before i run all the tests again (I appreciate your assistance and don't want to waste your time either). :T

Woofer to front of woofer 60", Horn driver to front of horn 32.1... which leave a difference of 27.9", and we currently have the horn delayed 2ms. If I am understanding this correctly... We need to have 0 ms for the horn and XX for the woofer since the horn length is shorter than the woofer length... Or do i have this backwards?


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## NBPk402 (Feb 21, 2012)

Here is the original Center horn 2ms delay from above... Followed by the same horn with the 3.45 ms delay. Last image is complete center channel sweep with horn having the 3.45 ms delay.
http://www.mediafire.com/download/2ade1r1wlcd13d6/center_channel_with_2_ms_and_3.46_ms_delays.mdat

Here is the data file for the Center channel...
2 ms delay for horn only
BB only
2 ms delay complete center channel

3.46 ms delay for horn only
3.45 ms complete center channel

If you want me to keep subtracting .4ms and repeating (assuming we went too far)...let me know and I will do that. I am assuming that we are to stop when we have the highest spl (if I understood you correctly).


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## NBPk402 (Feb 21, 2012)

I looked at the sweep for the 2 ms and the 3.46 ms, and it appears the spl went down by about 3db... Is it supposed to do that or did we go too far?


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## jtalden (Mar 12, 2009)

I wasn't clear so I will try again:

The only thing that is useful at this time is an .mdat file that contains 3 measurements on the left channel.
1. H (with MiniDSP delay set to 3.45ms)
2. BB (with MiniDSP delay set to 0.00ms)
3. BB+H (with MiniDSP delays set as noted in 1 and 2) 

this is the series of 3 measurements that are needed for this type of analysis. All the other driver/channel/delay measurements just confuse the issue for me.

I was going to look at the center channel measurements per post 24, and see if the correct series of 3 measurements were included for that channel. I was unsure if the delay settings were really correct and if the 3 needed measurements were really there, but I was going to look to try to find out. However, after several tries and continued warnings from my security software about the download site being a known security risk, I have been unable to download that file. I am not sure why as it worked before with the same warnings.

As a result, I am asking you post the file here on HTS. If you use 256k sweeps the file will be smaller, but I would think 3 measurements at 1M length measurements should be okay for size. If not, just zip the file and attach it as a .zip.

If you tested with the delays per this post and say there is a 3dB loss of SPL in the XO range then, yes, that is a problem. The measurements should look the same as my analysis predicts in Post 16. That makes this confirmation step more important. I may have made a mistake or possibly you did not set the MiniDSP delays correctly. 

I hope is now clear what 3 measurements are needed and where the file should be posted. Sorry for the earlier confusion.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> I wasn't clear so I will try again:
> 
> The only thing that is useful at this time is an .mdat file that contains 3 measurements on the left channel.
> 1. H (with MiniDSP delay set to 3.45ms)
> ...



I hope I have this right... 3.46ms delay on the horn, 0ms delay for the BB, Data file uploaded here. :T


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## jtalden (Mar 12, 2009)

Yes, that is just what I needed to see.

The data looks exactly as predicted. The delay setting is now optimized.

The SPL support in the XO range, the phase tracking and the group delay is all now optimized for the 500Hz XO. 

Just set the MiniDSP delays the same for the other 2 front channels and you are then ready to move on to your next steps. :sn:


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Yes, that is just what I needed to see.
> 
> The data looks exactly as predicted. The delay setting is now optimized.
> 
> ...


Thanks for helping me get this far! I have the crossovers all setup the same now. Next step is the REW Auto EQ, correct? How do i know what parameters to set it to?


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## jtalden (Mar 12, 2009)

There are many options as to how to finish the setup and set EQ. 

I thought you intended to use Audyssey for the next step. It will set all the channel distances (delays) and EQ your system. If you are then happy with the results, you are done.

After Audyssey sets distances and EQ it can be turned off if you like and the distances will still be set correctly.

You could also set the distances manually by tape measure. You don't have the right mic to set them using REW measurements. Although, there is recent thread on how that might be done. You could probably use HolmImpulse or Arta . I think either has that capability with a USB mic?

Manual EQ is large subject with lots of options. I don't use the recommended method as I have had better results using an alternate method. It is best for someone else to provide manual EQ assistance if that is where you intend to go.

A new thread may help get that started unless someone else jumps in here.


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## NBPk402 (Feb 21, 2012)

Thanks again for your assistance! My system sounds much better now. The only reason I wanted to AutoEQ is so when I listen in "Pure Direct" mode (stereo with no Audyssey) it would sound as good as it can. I can live without AutoEQ mode for now... Now to have another movie/music night, and see what everyone else thinks of it now.


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## NBPk402 (Feb 21, 2012)

When I installed the new power amps, and Dirac, I had to retune my setup. Does this look good? I am thinking that the current crossover could be moved down to 400-450hz? What do you think?



This what I did in my MiniDSP to the settings...

This is the miniDSP horn settings for a 500Hz 24LR crossover:



This is for the Bass Bins:



Here is my REW file:


Hopefully we are looking good again. I want to get the horns, and BB correct before I move on to the subs.:T


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## jtalden (Mar 12, 2009)

New amps and Dirac will not impact the delay settings. So if the room positions for all the drivers and LP are unchanged the delays are still correct. 

Dirac will EQ and probably also linearizes the Phase for some or all the frequency range. I am not a Dirac user so I don't know for sure. This process will not change the XO timing that was set. That is it will not change it if the Dirac filter is applied to the channels; left horn/BB and right horn/BB.

If a Dirac filter is applied to each driver individually and you are then needing to determine the delays between the horn BB with the new Dirac filters applied then the timing should be checked to assure it is correct.

I can't comment specifically as to any XO freq change or delay timing yet as there is not enough info in your Posted measurements and settings information. 

Regarding EQ it looks like you have boosted the BB at the XO and shelved up the range above that leaving the important 80-300 range too low compared to the rest of the range. 

If your delays and XO are set the then:
> Adjust the relative levels of the horn and BB to about equal with no EQ applied. 
> Set the XO and delays for the SW to BB XO and adjust the relative levels so then also are about the same.
> Then drive each channel and apply EQ as needed to that channel to smooth the response. Dirac can do that for you, or if you again will be bypassing Dirac for some situations, then you can do that with the MiniDSP before Dirac is run.

I hope this is helpful, but I am not really sure of the situation so I may not be.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> New amps and Dirac will not impact the delay settings. So if the room positions for all the drivers and LP are unchanged the delays are still correct.
> 
> Dirac will EQ and probably also linearizes the Phase for some or all the frequency range. I am not a Dirac user so I don't know for sure. This process will not change the XO timing that was set. That is it will not change it if the Dirac filter is applied to the channels; left horn/BB and right horn/BB.
> 
> ...


So basically go back to my original crossover settings, and then just run a test tone to get the BB, and the horns at the same SPL, correct?


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## jtalden (Mar 12, 2009)

Yes, use the same delays as before.
Instead of level matching with a test tone, I suggest adjusting the 2 levels by looking at the REW SPL chart showing the 2 traces. Just make the overall levels of the BB and horn as evenly matched as possible without EQ active. That will help minimize the total amount of EQ required.

If you do want to confirm the timing is still correct that can also be done if you like. It should not have changed though. As before, with XO active and the delay set, 3 measurements are required on one channel with mic at the LP; BB, Horn, BB+Horn. The SPL overlay chart should look like it does in the first chart of Post 16. The BB+H trace shows good SPL support throughout the XO range with 1/3 or 1/6 smoothing. I can also confirm timing is correct (or suggest a needed adjustment) if you post the mdat containing the 3 measurements.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Yes, use the same delays as before.
> Instead of level matching with a test tone, I suggest adjusting the 2 levels by looking at the REW SPL chart showing the 2 traces. Just make the overall levels of the BB and horn as evenly matched as possible without EQ active. That will help minimize the total amount of EQ required.
> 
> If you do want to confirm the timing is still correct that can also be done if you like. It should not have changed though. As before, with XO active and the delay set, 3 measurements are required on one channel with mic at the LP; BB, Horn, BB+Horn. The SPL overlay chart should look like it does in the first chart of Post 16. The BB+H trace shows good SPL support throughout the XO range with 1/3 or 1/6 smoothing. I can also confirm timing is correct (or suggest a needed adjustment) if you post the mdat containing the 3 measurements.


When we were setting up the Dirac with the new amps I inadvertently wired the crossovers backwards, and the bass notes went to the horns. I thought the drivers were blown, and purchased 3 more (which I now have in the system). I am not liking the response out of them as they don't appear to be as smooth as the original drivers. I had the old drivers tested , and only one was blown. The blown one has a new diaphragm in it. I am going to swap out the current drivers for the old ones, and then run REW all over again. Hopefully the older drivers will give me the performance back that we had before. I will post them up as soon as i get them swapped. I have already reverted to the old crossover setup, and set the levels again. They sound pretty good but Anna Kendricks voice is off when I watch Pitch Perfect (so something is still wrong). I would appreciate it if you could look into my settings again once I get the new drivers in place. :T:T


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## jtalden (Mar 12, 2009)

That is no problem. When you are ready:
> Activate your XO.
> Deactivate all EQ settings in the MiniDSP and Dirac.
> Sweep full range (minimum range is 50-4k) with mic at the LP.
> 3 measurements of the Left main (or the Right main - not both).
1. H (with MiniDSP delay set to 3.45ms)
2. BB (with MiniDSP delay set to 0.00ms)
3. BB+H (with MiniDSP delays set as noted in 1 and 2)
> Post the mdat here and I will confirm the settings.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> That is no problem. When you are ready:
> > Activate your XO.
> > Deactivate all EQ settings in the MiniDSP and Dirac.
> > Sweep full range (minimum range is 50-4k) with mic at the LP.
> ...



I have a lot of hiss coming from my horns right now. MiniDSP told me to attenuate, and or lower the dip switches on the Dirac. I will have the attenuators by Friday. If you want to wait until after they are installed and the hiss is gone... let me know.

All of the above have been done except the delay is 3.46 (it moves in 2db increments)

Left Horn: (The horn gain (output) is cut by 12db in MiniDSP...other than that nothing but crossover at 500Hz LR24db.)



Left BB:



Fullrange:




This time it looks like the crossover could go even lower than 500Hz...should I try it lower? Let me know if you want anything else posted.

tia,
Ron


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## jtalden (Mar 12, 2009)

I looked at the mdat file.
> No problem using 3.46ms for the delay.

There are some problems with the measurement setup though; one is serious.
1. Serious - 2 sweeps were used with a USB mic. That does not work correctly. 
[The timing between the sweeps is lost and that probably accounts for the variability in the SPL charts and the unusual looking IR charts.]
2. Minor - The Mic calibration file is loaded as the soundcard calibration. This may not be a problem with the resulting charts, but it is better practice to load the file into the appropriate location. Be sure the soundcard cal is then set to 'None'.

> The 2 sweeps issue prevent me doing any analysis of the XO timing. The same 3 measurements will need to be redone using one sweep. Repost the resulting mdat.

> I cannot comment specifically on any XO frequency change as I do not know the response characteristics of the BB and Horn without the XO active. Normally a freq is chosen that is at least 1 octave above the natural cutoff of the Horn. So if the Horn cutoff off is roughly -3dB at 250Hz then the 500Hz XO is a typical choice. There are lots of things that can influence the decision however so 'typical' is often not used. With a large horn that is operating in a small room and with the 24dB/octave XO being used there little to no risk of damage to the driver to go lower. It may, or may not sound better. There is no way for me to know what the best choice is. Go lower if you like and try it out. Do *not* go lower than the natural rolloff frequency of the Horn.

> Yes, Attenuators can help with large horn hiss. If your new P-amps have an input level/gain control that is the same thing. Just reduce the input gain using that control. Once the EQ is adjusted properly that may help a lot also.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> I looked at the mdat file.
> > No problem using 3.46ms for the delay.
> 
> There are some problems with the measurement setup though; one is serious.
> ...


So for the sweep, I changed it to 1 sweep.

Do I need a new mic? I am using the UMIK-1 mic (same as before).
When you say do not go lower than the natural rolloff frequency of the horn... Do you mean the natural rolloff frequency of the horn or the driver? The driver says to 500hz, but the horn says 300hz. 

My new amps have no level or gain adjustments. All adjustments must be done at the preamp or my Oppo 103 (which I am using for volume control). I went to clear the soundcard calibration and then it didn't show any mic cal, so i put it back in...is it showing the proper one for you now? It never asked for the mic calibration like the instructions showed this time.

Horn only...


BB only...


Fullrange...


Does that look better now? Any more info needed?


tia,
Ron


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## jtalden (Mar 12, 2009)

Okay, those measurements can be used to establish timing.

Current ('orig' one my charts below) Horn Delay = 3.56ms
New Horn Delay = 2.74ms

I don't know what has changed from the last setup that could have caused this, but the new horn timing is needed achieve good SPL support through the entire 300-900Hz XO range. Below are charts showing the Orig vs New impact to SPL. The new phase tracking is also shown.

























Other comments:
1. Both the horn and the BB are now set to negative polarity. This probably is fine for sound quality, but to be more conventional you should reverse the polarity on both drivers. Be sure the other channels are also then set the same. [This way Dirac will see a normal Positive Polarity when it sets the EQ and it is sure to not be confused. It probably handles it fine automatically, but it's best to be safe.]

2. The mic calibration is still loaded as a soundcard calibration. Remove the file from Preferences/Soundcard and place it in Preferences/Mic-Meter. As stated above this will not impact the results here. It's better housekeeping.

3. I could not recommend lowering the XO below the recommend limit for the horn driver of 500Hz.

4. You don't need a new mic. Your current mic is very popular and widely used. It's difficult to set driver delay timing using the phase tracking approach using REW and a USB mic, but I just did that for you, so no problem.  We could have used the RTA feature in REW to dial in the timing with that mic with results that would be just a good.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Okay, those measurements can be used to establish timing.
> 
> Current ('orig' one my charts below) Horn Delay = 3.56ms
> New Horn Delay = 2.74ms
> ...



Thanks for all your help. I changed the delay on the horns as you specified. I inverted the Polarity in the MiniDSP 2x4s for all 3 front channels (horn, and bass bin). How do I tell on each speaker if it is reversed or not in REW? I saw your Polarity post, but I don't know how to tell which is which. I also went in, and corrected the mic calibration so it is in the right place. Also how do i check the delays for the other 2 front speakers (I know they are the same but due to positioning I am curious as to whether they should be the same, plus it would be nice to know how to do it).

tia,
Ron


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## jtalden (Mar 12, 2009)

Good.

Polarity:
The direction of the initial rise of the IR is a good indicator; positive rise = positive polarity. That is all I did late last night. That is pretty reliable for direct radiators; cones and domes. There can be some confusing factors that make this more difficult to decide in some cases. Checking it again this morning as a result of your question I am not sure that either choice is more correct than the other as practical matter. Horns often seem to have shift in phase at the top end of their range. I assume the driver is actually unloading from the horn when the wavelength gets down to the dimension of the throat of the horn (just my guess, I haven't studied horn design). Another practical indicator for effective polarity in my opinion is to set the driver covering most of the 2k-10k range such that its phase can be adjusted to be flat near 0° over most of that range. In this case the horn covers that range and making the bulk if that range as flat a possible results in a choice of either +90° or -90° from 2k-8k and then the phase swings back to 0° or 180° for 13k-20k. Your initial settings resulted in 0° in that range.

The bottom line for me is now that either choice is as correct as the other in this case. Neither should have any sound quality impact. I assume Dirac is well equipped to deal with either situation. The more important part is that the BB and the Horn have the polarity settings that results in the closest phase tracking throughout the XO range. Either of choices retains this condition.

Confirmation of Delay Settings:
Yes, it's a good idea confirm the delays. I make mistakes sometimes in my analysis. The process is easy. With the new delay settings run the same 3 measurements as before and confirm that the SPL overlay chart agrees with my 2nd chart in Post 41. The SPL of the combined BB+Horn trace should be above the 2 individual traces from 300-800Hz. The other 2 channels can be tested the same way.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Good.
> 
> Polarity:
> The direction of the initial rise of the IR is a good indicator; positive rise = positive polarity. That is all I did late last night. That is pretty reliable for direct radiators; cones and domes. There can be some confusing factors that make this more difficult to decide in some cases. Checking it again this morning as a result of your question I am not sure that either choice is more correct than the other as practical matter. Horns often seem to have shift in phase at the top end of their range. I assume the driver is actually unloading from the horn when the wavelength gets down to the dimension of the throat of the horn (just my guess, I haven't studied horn design). Another practical indicator for effective polarity in my opinion is to set the driver covering most of the 2k-10k range such that its phase can be adjusted to be flat near 0° over most of that range. In this case the horn covers that range and making the bulk if that range as flat a possible results in a choice of either +90° or -90° from 2k-8k and then the phase swings back to 0° or 180° for 13k-20k. Your initial settings resulted in 0° in that range.
> ...


Thanks for the info, and help. I am going to re run the tests today after my attenuators arrive...hopefully I can get rid of the hiss. Sounds like a noisy record without the pops. 

I was generally very impressed with the crossovers last night. I have a test i do for seeing if anything is wrong (play Pitch Perfect songs in the movie), and up until last night I was unable to get Anna Kendricks voice to sound right. After changing the delays and reversing the polarity (and running Dirac again) her voice is back to where it was with the Audyssey setup. Right now I need to play with the bass. The bass sounds great, but I think I boosted it a little too much as it is not quite as tight down low as it was.


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## NBPk402 (Feb 21, 2012)

I removed the MiniDSPs due to excess hiss, and replaced the crossovers with a Xilica XP-4080. I matched the settings the best I could, and even switched the Polarity to negative. These are the results of the left speaker.

Left Bass Bin


Left Horn


Left Channel (horn and bass bin)


I think it is pretty close to where it was before I switched to the new crossovers. Is it good now?


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## jtalden (Mar 12, 2009)

I just checked the mdat file and the delay timing is still perfect. The SPL support is through the entire XO range is optimized.


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## NBPk402 (Feb 21, 2012)

What i find strange is that i had a problem with REW, and I uninstalled it... When I installed a fresh copy it doesn't ask me for my calibration, it doesn't ask me to calibrate the levels either. I also noticed that it doesn't give me an option to select any other channel. I was shocked that it gave me such a flat response. I hope that it is correct.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> I just checked the mdat file and the delay timing is still perfect. The SPL support is through the entire XO range is optimized.


That is awesome. It is the flatest i have ever seen on my setup.:T:T


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## jtalden (Mar 12, 2009)

Ron,
The timing is still great. 

The look of flatness in your Posted SPL charts is just because the scaling of the chart is so large (20dB per grid line). Rescale the SPL axis so that you see 5dB increments per grid line. The variability will then look more typical.


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## NBPk402 (Feb 21, 2012)

jtalden said:


> Ron,
> The timing is still great.
> 
> The look of flatness in your Posted SPL charts is just because the scaling of the chart is so large (20dB per grid line). Rescale the SPL axis so that you see 5dB increments per grid line. The variability will then look more typical.


Ooh... Now I know why it came out looking so good.  :T:T


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