# Measuring Impulse Response for TA using REW and Umik-1



## forty5cal1911 (Sep 11, 2006)

I have been searching for a method to do this and haven't found much all in one place so I thought I'd post my results and findings here in the hope that others who are looking might have an easier time finding info.

So, let's begin... Accurate IR measurements can be obtained from a USB mic by using the Acoustic Timing Reference. This has been stated on this forum, REW, diyaudio etc. However, there is very little info I've been able to find describing how to set that up and interpret the results.

The equipment I'll be using for this is Room Eq Wizard 5.18, a MiniDSP Umik-1 mic and the Helix DSP.2 processor running v4 Software.

You'll need a 3.5mm to RCA (Y adapter) in order to utilize the Analog output on your on board Soundcard.

It goes without saying that you'll need to configure your mic and calibration file in REW. Once that's done you will need to configure an Acoustic Timing Reference as well as your desired output. 

Go ahead and plug in your Y adapter to your onboard sound card and connect the Left and Right channels into your DSP Analog inputs while the DSP is powered down.

Open Room Eq Wizard
Go to Preferences > Analysis
Choose "Acoustic Timing Reference" from the drop down menu

Note: The "Set t=0 at IR peak" by default is checked and greyed out. This is primarily why the delay values generated by REW that you see in the Measurement Notes are inacurrate. Either way I prefer to manually calculate this as you will see.

Now go to Preferences > Soundcard for the "Output Device" choose your onboard Soundcard in the drop down menu (or any Soundcard you have installed that has an Analog output)
For the "Output" choose your Analog output - this could be variable depending on your system and the output naming in my case this is labeled "Speaker"
The drop down box that contains "Left" "Right" or "Both" will configure the default output channel(s) when performing a Measurement using Acoustic timing
Choose "Left" from the drop down menu
Make sure your Mic is recognized and configured as the Input Device on the Soundcard tab
Close Preferences

In this tutorial we'll be using Analog Input Channels 1 & 2 on the Helix DSP.

Connect to your DSP and launch the Software. Now we're going to route the Channels to the necessary outputs.

Since the furthest driver from the LP is usually the passenger midbass that's the channel we'll choose for our Acoustic Timing Reference (this should be configured for your further distance driver). 

So we will route Analog Input 2 (Right Channel Input) and route it to the Right Midbass which is Channel F in my setup.
Now we need to route the Signal Channel. We will route Analog Input 1 (Left Channel Input) to the Right Midbass which is Channel F in my setup.

Note: We are routing both the signal and timing reference to the Right Mid Bass driver to establish our reference measurement.










Mute all other output Channels in your DSP
Bypass the low pass filter on your midbass output channels in your DSP

Adjust your Volume Control in Windows to an appropriate volume level

Click Measure in REW
In the measurement window it should have "Use acoustic timing reference" displayed
Choose 1000 Hz as the Start Freq and 1001 Hz as the End Freq choose an appropriate db level

Note: Low frequencies cannot be used for IR as the wavelengths are too long. You will need to choose a freq that can be safely played on each of your drivers. I use 2.5k for tweeters.
Select 128k for the length to give us the shortest amount of sweep time
Make sure the correct Ouput is displayed in the measurement window
Make sure "Right" is displayed as the Timing Reference Output
Make sure "Wait for timing reference" is checked










Click "Check Levels" to make sure you are not clipping anything in the IO chain
Click "Start Measuring"
Once Measurement Completes rename to something like Right Midbass IR Reference
Click on the Impulse tab
Change dbFS to %FS
Zoom in on the Graph at 0










Change routing in your DSP to Left channel -> Left Midbass
Unmute the Left Midbass Output Channel in DSP










Click Measure in REW
Click "Start Measuring"
Once Measurement completes rename to something like Left Midbass no TA

Open the Overlays window in REW
Go to Impulse tab
Change dbFS to %FS
Zoom in on the Graph at 0
Once you see the scale at 0 - 2m that should be sufficient
Make sure that both Measurements are visible in your Overlay window
Click on the Graph at the first point where the Impulse begins to rise for the Left Midbass Measurement
You will get the blue crosshairs and a time in milliseconds










Plug that number into your Calculator in Windows
Follow the Blue line to the right until it intersects the Impulse response for the Reference Midbass
Click on the Graph at that point










Subtract that number from the first in your Calculator
This will leave you with the amount of delay to add to your Left Midbass, in our example 1.27ms

Add the Delay in your DSP for your Left Midbass Channel

Run another Measurement in REW
Rename it something like Left Midbass w TA
Open Overlays > Impulse tab and remove the Left Midbass no TA from view
You should now have an aligned Impulse Response










Repeat the process for your other Drivers and ENJOY!

I have performed TA via tracerite, doppler effect, inverted phase and tones and this method. I've gotten far better results with this method although the phase and tones did arrive at closer numbers to the IR measurements.

Give it a shot and see what you guys think.


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## bnae38 (Oct 3, 2015)

Curious where you positioned mic? Center of head?


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## forty5cal1911 (Sep 11, 2006)

Yes center of head estimated ear level.


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## naiku (May 28, 2008)

Might have to give this a shot, I used HolmImpulse to measure mine and it worked in much the same way. But, it would be nice to have one less program on my laptop! Thanks for writing this up.


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## forty5cal1911 (Sep 11, 2006)

naiku said:


> Might have to give this a shot, I used HolmImpulse to measure mine and it worked in much the same way. But, it would be nice to have one less program on my laptop! Thanks for writing this up.


Absolutely! My small contribution to the vast knowledge base contained here.

The problem with Holmimpulse is that the time locking function can't work due to the usb mic and soundcard output having completely separate clocking mechanisms. This can lead to completely erratic measurements.


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## Ziggyrama (Jan 17, 2016)

Any reason why I cannot feed the signal via AUX port into my HU to record the IR?

Thanks for the writeup, I may try this to verify my TA.


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## 94VG30DE (Nov 28, 2007)

Keeping this for later, thanks!


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## SkizeR (Apr 19, 2011)

Stickystickystickysticky


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## Swaglife81 (Oct 15, 2016)

These are the kinds of threads we need. I'm sure many will appreciate this


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## oabeieo (Feb 22, 2015)

I was just tellin someone about that the other day. 
Thanks for taking the time to explain it. I've been using this for awhile now and it works well. 

The little chirps threw me off when it came out of only one side and kept errors for right side
Took me a week to figure out the y cord that important. Glad you said I can change it to both I missed that


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## Mlarson67 (Jan 9, 2015)

Subd


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## solacedagony (May 18, 2006)

Tying this together with other TA information.

http://www.diymobileaudio.com/forum.../145484-measure-time-delay-t-arta-roomeq.html


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## sq2k1 (Oct 31, 2015)

sub'd.... thanks for making the post and sharing.


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## alachua (Jun 30, 2008)

I think it would be a valuable resource if some of the contributors would be willing to put together a 'using REW in the car' wiki. It is somewhat tough to find all the best threads, evaluate if they are up to date (for instance, using impulse response replaces a number of previous methods for calculating delays) and finding some of the other awesome tools members of the site have put together.

Anyone up to the task?


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## sq2k1 (Oct 31, 2015)

I am guessing you mute any unused speaker as you progress along such as when you move from the right midbass to the left midbass? Maybe it is rather obvious, but I am curious nonetheless....


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## thebookfreak58 (Jun 18, 2012)

Remember, align the peaks for high frequency drivers, align the rise (as it starts to go positive direction) for low frequency.


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## banshee28 (Mar 23, 2006)

I currently have my TA set by physically measuring. I will be trying this out later this week and want to "see" how it makes a difference. I hope I can tweak things even better using this.

Thanks!


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## forty5cal1911 (Sep 11, 2006)

Ziggyrama said:


> Any reason why I cannot feed the signal via AUX port into my HU to record the IR?
> 
> Thanks for the writeup, I may try this to verify my TA.


You didn't say what equipment you are using but I don't see why not provided you have individual channel mute capability and DSP input routing capability.


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## forty5cal1911 (Sep 11, 2006)

thebookfreak58 said:


> Remember, align the peaks for high frequency drivers, align the rise (as it starts to go positive direction) for low frequency.


:thumbsup:

I'll post a pic of 2.5k tweeter alignment when I can get a few minutes.

sq2k1:



sq2k1 said:


> I am guessing you mute any unused Speaker as you progress along such as when you move from the right midbass to the left midbass? Maybe it is rather obvious, but I am curious nonetheless....


That is correct as a best practice. Since you are controlling the input routing it really shouldn't matter so much as you are routing the "Left" Channel to a particular driver. For example for your Right Midrange you will be routing the left input signal to your right midrange output channel. Everything except the reference channel and the right midrange should be muted.

To everyone, glad to have such a great enthusiast community here! Hope this helps anyone get your TA dialed in much faster and more accurately. Please share your results in this thread.


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## Ziggyrama (Jan 17, 2016)

forty5cal1911 said:


> You didn't say what equipment you are using but I don't see why not provided you have individual channel mute capability and DSP input routing capability.


The easiest way for me is to run audio out of my laptop into my HU via AUX port. So, that means: LAPTOP - aux -> HU - rca -> DSP - rca -> AMP - wire -> SPEAKER. I can mute each channel individually on the DSP. I asked the question since it seems much easier to feed the signal in from REW via AUX input from a laptop rather than using splitters and adapters. Anyways, I think my input method is fine, just wanted to confirm.


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## naiku (May 28, 2008)

alachua said:


> I think it would be a valuable resource if some of the contributors would be willing to put together a 'using REW in the car' wiki. It is somewhat tough to find all the best threads, evaluate if they are up to date (for instance, using impulse response replaces a number of previous methods for calculating delays) and finding some of the other awesome tools members of the site have put together.
> 
> Anyone up to the task?


Let me see if I can make some headway on this, I have a couple bookmarked already and will see if I can at least compile a thread containing all of them. It can be tough since searching for "REW" is not helpful.


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## josby (May 8, 2011)

Very cool! I had wondered how to do this with REW. Thanks


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## tonny (Dec 4, 2010)

The only problem is when you bypass the crossover you will change the timing off the driver, when you put an filter on a driver it will have more delay trough the dsp, so always time it with the right crossover on it to get it right, when both impuls response are at the same time, look at the frequentie response and see if both channels ad up 6db if played at the same time over it's compete response and check by making small changes in the timing to see if you can make it even better! Do this the same between mid and mid bass and so on.


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## banshee28 (Mar 23, 2006)

Having an issue getting this going. I originally had an older Beta version so I uninstalled that, updated to the latest Java 8 112 and rebooted. Installed REW V 5.18 and tried again. Same error.

Basically either testing with laptop speakers or connected to my DSP, after I start the measurements, it never "completes". It sits there indefinitely. I cancel it and REW is mostly frozen, and mostly grayed out. 

Here is the starting measurement window that never completes:
 

Once I cancel it, here is how it looks:


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## forty5cal1911 (Sep 11, 2006)

Drop down the Menu on "Output" in the Measurement window and choose the output rather than "Default Output" Mine is listed as Speaker


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## banshee28 (Mar 23, 2006)

forty5cal1911 said:


> Drop down the Menu on "Output" in the Measurement window and choose the output rather than "Default Output" Mine is listed as Speaker


Yes I noticed yours was speaker. I did just try that now and its doing the same thing. Weird.
The only thing I can do once this is started, is to exit out of REW. When i do it asks me to save the file, although I can never view it. Even if I save it its not "real/complete".
I think its something I am choosing in the Soundcard preferences. So.....I have Driver:Java, Output Device: Primary Sound Driver, Input Device: UMIK-1. Seems like no matter which options I choose, it freezes up. Again older version did the same, uninstalled and latest is doing it also. I spent hours doing FR with REW, and no "major issue" with the app??


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## forty5cal1911 (Sep 11, 2006)

You should have another option on Output Device and it should be labeled the same as your Sound card in Device Manager. That's the one you want to choose.


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## banshee28 (Mar 23, 2006)

forty5cal1911 said:


> You should have another option on Output Device and it should be labeled the same as your Sound card in Device Manager. That's the one you want to choose.


Ok, so I checked DM and its listed as Conexant SmartAudio HD. Back in REW under pref's > Soundcard > Output Device, I see it as Speakers (Conexant SmartAudio HD). So I choose that, then the Output is Speakers "Left", Input Device (testing locally on laptop) is Internal Mic, Input is Microphone. Still hangs calculating frequency?


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## banshee28 (Mar 23, 2006)

I figured it was something I changed or had set under preferences. I guess the uninstall and re-install does not change/remove those settings. I went under Preferences and choose to Delete Preferences and Shutdown. Now things seem to at least work and show the charts!!

Now I will hookup back to the DSP and see...Thanks


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## forty5cal1911 (Sep 11, 2006)

Excellent! Let us know how it goes.


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## banshee28 (Mar 23, 2006)

Well the charts are mostly working but something is still wrong! I finally noticed that my furthest speaker Right Tweet (Ref) is past the "0" on the charts! Therefore no matter now much delay I add to the DSP for the Left Tweet it never moves enough to the right to match the right. I noticed all your charts are all under 0ms for the first peaks.


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## forty5cal1911 (Sep 11, 2006)

What is the delta in milliseconds between the rise of the first peak in your Reference Measurement and the first peak in your Left Tweeter Measurement? This is the amount of delay necessary to add to your left tweeter. 

This is found by going to the Overlays Window on the IR tab and using the cursor to click on the graph to get the cross hairs. Follow the directions in my first post substituting your drivers for mine.

Also, make sure there is no delay in your DSP being applied to your right tweeter.


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## banshee28 (Mar 23, 2006)

forty5cal1911 said:


> What is the delta in milliseconds between the rise of the first peak in your Reference Measurement and the first peak in your Left Tweeter Measurement? This is the amount of delay necessary to add to your left tweeter.
> 
> This is found by going to the Overlays Window on the IR tab and using the cursor to click on the graph to get the cross hairs. Follow the directions in my first post substituting your drivers for mine.


Thanks, I am pretty sure I am following "most" of them correctly. 
All of my measurements seem to be in "u" micro seconds I guess vs ms. For example, the Right side Reference tweet (0 ms on dsp) has the first peak at 10.0u, and the left tweet (also 0 ms on dsp) was -20u (both aroud 75 %FS). So it seems like my reference is already passed "0" on the bottom scale. No matter how much delay I add to the Left Tweet, the first peak never goes further than "0". SO there is always a gap. I know something is wrong, just not sure what. 
I will try to post a chart soon from the laptop.


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## forty5cal1911 (Sep 11, 2006)

Forget 0 on the bottom scale altogether. 

Zoom in on the Graph so you can clearly see the first IR Peak. Click on an area of the left Tweeter first peak. You will get the blue cross hairs and a blue box at the bottom of the window with a number in it. Make a note of this number. Follow the horizontal portion of the blue cross hair and click where it intersects the first peak of your Reference measurement. Make note of the number in the box at the bottom.

The difference between these numbers is the time in ms to delay your left tweeter.


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## subterFUSE (Sep 21, 2009)

ETC does a better job of finding the first peak than the IR does.


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## forty5cal1911 (Sep 11, 2006)

subterFUSE said:


> ETC does a better job of finding the first peak than the IR does.


Thanks subferFUSE it definitely does! I had no idea. You can clearly see the impulse rise much more clearly in the ETC tab.


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## subterFUSE (Sep 21, 2009)




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## forty5cal1911 (Sep 11, 2006)

banshee28 said:


> ....the Right side Reference tweet (0 ms on dsp) has the first peak at 10.0u, and the left tweet (also 0 ms on dsp) was -20u (both aroud 75 %FS).
> I will try to post a chart soon from the laptop.


Must have glossed over this earlier but man if you've got ~10ms (I hope that was a mistype on your part because ~30ms would be crazy) between the Impulses something is definitely wrong.

Post up your graphs when you can.


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## banshee28 (Mar 23, 2006)

forty5cal1911 said:


> Forget 0 on the bottom scale altogether.
> 
> Zoom in on the Graph so you can clearly see the first IR Peak. Click on an area of the left Tweeter first peak. You will get the blue cross hairs and a blue box at the bottom of the window with a number in it. Make a note of this number. Follow the horizontal portion of the blue cross hair and click where it intersects the first peak of your Reference measurement. Make note of the number in the box at the bottom.
> 
> The difference between these numbers is the time in ms to delay your left tweeter.


I hear ya, I thought this would be pretty simple. Here is a chart with the Purple being the Left tweet, the crosshairs show about -20u for that and about 20u for the Green Right tweet. So about 40u or .4ms. I dont think this is right, as using the tape measure it was ~1.48ms. Either way, once set on the DSP it does not improve.

Here is a chart with a 4ms delay and the max delay 15ms (pruple) on the Left Tweet and its still not lining up with the RIght.


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## forty5cal1911 (Sep 11, 2006)

.4 ms could be fine. That's about what it looks like it should be from the graph. The second graph with the .4 ms delay looks correct as the peaks are right on top of each other. You can verify this by playing a tone that is the passband of your tweeters and adjusting delay a couple of clicks on the left tweeter. You will hear it go out of phase (less amplitude), now move it back and you will hear it go back in phase (more amplitude). It does not take much on the high freq spectrum.

Continue on for your other drivers using the right tweeter as reference.

What freq are you using for your sweep?


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## banshee28 (Mar 23, 2006)

forty5cal1911 said:


> .4 ms could be fine. That's about what it looks like it should be from the graph. The second graph with the .4 ms delay looks correct as the peaks are right on top of each other.
> 
> Continue on for your other drivers using the right tweeter as reference.
> 
> What freq are you using for your sweep?


since I had the tweet XO at 3500, I set the XO to 2500 and the sweep to 3500. Yes those charts are almost on top of each other, however I think they are both Left, and the one to the right is the RIGHT Tweet I am trying to match right?
Also I then tried to the work on the mids using the 1000Hz. For these I could never get it to pass waiting for timing reference. I will post my Preferences as maybe there is something wrong!


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## subterFUSE (Sep 21, 2009)

You need to do time alignment before crossovers. The crossover distorts your impulse response


Sent from my iPhone using Tapatalk


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## banshee28 (Mar 23, 2006)

subterFUSE said:


> You need to do time alignment before crossovers. The crossover distorts your impulse response
> 
> 
> Sent from my iPhone using Tapatalk


So if that could be the difference here, that was one direction I apparently did not follow, lol. Could it be the issue... Let me try that.


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## forty5cal1911 (Sep 11, 2006)

Yes you need to disable your crossovers while performing TA.


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## Ziggyrama (Jan 17, 2016)

forty5cal1911 said:


> Yes you need to disable your crossovers while performing TA.


What is the reason for that?

FYI, LPF and HPF introduce delay and lead respectively. I imagine you'd want to take the measurements with the filters on when aligning different drivers to account for that effect?


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## subterFUSE (Sep 21, 2009)

They don't introduce delay. They rotate phase. 2 different things altogether.

Use time alignment to set arrival. Then use crossover settings to get good alignment between drivers. If necessary, all pass filters can be used to fix phase issues that you can't get at otherwise.


Sent from my iPhone using Tapatalk


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## forty5cal1911 (Sep 11, 2006)

Ziggyrama said:


> What is the reason for that?
> 
> FYI, LPF and HPF introduce delay and lead respectively. I imagine you'd want to take the measurements with the filters on when aligning different drivers to account for that effect?


I have performed it both ways with no difference in the measurement results as long as you stay mostly in the passband of the drivers.

For midbass however you have to bypass the lowpass xover completely because you must use 1k and higher sweeps for Impulse Response measurements.

You are correct that the filter will introduce a phase shift resulting in change in delay. This obviously gets worse as the attenuation increases and steeper slopes will introduce that phase change more quickly.

While I was typing that subterFUSE gave a great explanation and advice.



> They don't introduce delay. They rotate phase. 2 different things altogether.
> 
> Use time alignment to set arrival. Then use crossover settings to get good alignment between drivers. If necessary, all pass filters can be used to fix phase issues that you can't get at otherwise.


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## Ziggyrama (Jan 17, 2016)

forty5cal1911 said:


> I have performed it both ways with no difference in the measurement results as long as you stay mostly in the passband of the drivers.
> 
> For midbass however you have to bypass the lowpass xover completely because you must use 1k and higher sweeps for Impulse Response measurements.


So what were your results when you tried to align in the crossover region? Isn't that the most critical area when aligning different drivers...Sub and midbass for example. If 1khz signal needs to be used, does that mean REW is useless for TA for sub and midbass alignment?


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## forty5cal1911 (Sep 11, 2006)

In my testing aligning right at the crossover point is okay and still accurate. As a best practice I would bypass the cross over in the area of alignment as I stated in my post. No matter what, you are going to invoke phase changes with any filter you apply that changes amplitude. You are attempting to align for wavelength arrival and thus phase using the delay. As subter so graciously pointed out we all must deal with the phase changes at xover region by using FIR filters, All pass filters or similar methods to best deal with those inconsistencies.

Yes impulse response for TA on sub to midbass is useless. ErinH did a good write up on his blog about the method he uses. I ended up with about 7 ms delay on my sub to get good integration.


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## Ziggyrama (Jan 17, 2016)

forty5cal1911 said:


> In my testing aligning right at the crossover point is okay and still accurate. As a best practice I would bypass the cross over in the area of alignment as I stated in my post. No matter what, you are going to invoke phase changes with any filter you apply that changes amplitude. You are attempting to align for wavelength arrival and phase using the delay. As subter so graciously pointed out we all must deal with the phase changes at xover region by using FIR filters, All pass filters or similar methods to best deal with those inconsistencies.
> 
> Yes impulse response for TA on sub to midbass is useless. ErinH did a good write up on his blog about the method he uses. I ended up with about 7 ms delay on my sub to get integration.


Can you point me at the write up that you mentioned? I used HolmImpulse to align my sub with my midbase and it was around 6.5ms delay IIRC which is a lot more than what tape measure suggested. Holm produced consistent results for me, using IR method, but I could not get the mids and tweeters aligned properly with it. Sounds like REW is going to do that for me.


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## forty5cal1911 (Sep 11, 2006)

Ziggyrama said:


> Can you point me at the write up that you mentioned? I used HolmImpulse to align my sub with my midbase and it was around 6.5ms delay IIRC which is a lot more than what tape measure suggested. Holm produced consistent results for me, using IR method, but I could not get the mids and tweeters aligned properly with it. Sounds like REW is going to do that for me.


Yeah delay in the low frequencies takes a lot larger values to swing the phase. Great write up and method by ErinH here.


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## banshee28 (Mar 23, 2006)

Bypassing the xo did help. Now the peaks are under 0ms. However should I change the sweep to 2500 vs 3500? I normally set the xo to 3500. Maybe this is an issue? I think I may have a L/R channel mixed up somewhere as things still dont seem right. Will try again tomorrow.


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## forty5cal1911 (Sep 11, 2006)

banshee28 said:


> Bypassing the xo did help. Now the peaks are under 0ms. However should I change the sweep to 2500 vs 3500? I normally set the xo to 3500. Maybe this is an issue? I think I may have a L/R channel mixed up somewhere as things still dont seem right. Will try again tomorrow.


3.5k should be fine as long as your midbass driver has okay response at that frequency and does not have erratic off axis behavior by then.


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## Babs (Jul 6, 2007)

subterFUSE said:


> They don't introduce delay. They rotate phase. 2 different things altogether.
> 
> Use time alignment to set arrival. Then use crossover settings to get good alignment between drivers. If necessary, all pass filters can be used to fix phase issues that you can't get at otherwise.
> 
> ...



Hmm. I wonder about this process then:
1 TA via IR
2 Crossovers to match sides
3. Individual driver EQ
4. Individual driver phase

Great write up Jazzi


Sent from my iPhone using Tapatalk Pro


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## subterFUSE (Sep 21, 2009)

An ideal tuning process for me would be this:

1. TA by IR/ETC.
2. EQ individual drivers flat.
3. Apply crossovers. Optimize by slope and freq choice. All pass filter if necessary.
4. Phase align subwoofer to mains using phase plot.
5. Apply tonality curve with input EQ.


Sent from my iPhone using Tapatalk


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## banshee28 (Mar 23, 2006)

Here are my settings shown on the measurement page in the first pic. Also in the second pic you can see where my Left Tweet is at 0m on the chart, and moves in one direction with 1ms delay but seems to move in another direction with less delay, All delay should move in the same direction right. Also, I DO have my DSP set with PEQ's on all channels. Would these have to be bypassed? Maybe I started this with too much already configured. Will test again today.


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## crackinhedz (May 5, 2013)

banshee28 said:


> Having an issue getting this going. I originally had an older Beta version so I uninstalled that, updated to the latest Java 8 112 and rebooted. Installed REW V 5.18 and tried again. Same error.
> 
> Basically either testing with laptop speakers or connected to my DSP, after I start the measurements, it never "completes". It sits there indefinitely. I cancel it and REW is mostly frozen, and mostly grayed out.
> 
> ...


I've been having issue with REW similar to you. Just freezes when trying to run a measurement, and have to exit out of REW. Very annoying. 

I updated to latest version of REW same problem.

It does run a measurement sometimes, but 9 out of 10 tries it freezes. A week ago it worked flawlessly. Though I recently did the Windows 10 anniversary update, perhaps it changed something.


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## banshee28 (Mar 23, 2006)

crackinhedz said:


> I've been having issue with REW similar to you. Just freezes when trying to run a measurement, and have to exit out of REW. Very annoying.
> 
> I updated to latest version of REW same problem.
> 
> It does run a measurement sometimes, but 9 out of 10 tries it freezes. A week ago it worked flawlessly. Though I recently did the Windows 10 anniversary update, perhaps it changed something.


 I would say it may be simply something in your "Preferences". I went under there and choose the Delete option and made one change at a time and eventually figured it out. I think I had the wrong Output selected and it locked up. Try that


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## Mlarson67 (Jan 9, 2015)

banshee28 said:


> I would say it may be simply something in your "Preferences". I went under there and choose the Delete option and made one change at a time and eventually figured it out. I think I had the wrong Output selected and it locked up. Try that


I had a similar issue running measurements. Was very simple fix. The first time I did some measurement I followed the OP to the tee and worked fine. Didn't like some of the settings so I tried to rerun and the measurement and it stopped at 19% every time we tried it. Found that I forgot to bypass the high pass filter on the right midbass


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## Ziggyrama (Jan 17, 2016)

I tried this method over the weekend and the results are as follows:

- I aligned the sub to my left mid using HolmImpulse and this method: The Subwoofer DIY Page v1.1 - Time Alignment using HolmImpulse. The result is very good, the bass is now up front, well integrated with midbass coming from the front. Interesting thing is that I had to add about 3ms of delay to my mid vs. what the tape measure was suggesting.

- Once I aligned the sub to the left mid, I used REW to align left and right mids. The important detail that I think is not explained well in OP's write up is the whole concept behind using acoustic reference for measuring IR. The way it works is that REW sends a chirp 1st through the reference speaker and then it runs a sweep using the speaker to be aligned to measure the IR relative to the chirp (your reference speaker). This is very important since if you don't get the chirp and sweep to go our the correct driver, you will either get the wrong values or you will see TA have no effect on your measurements. I believe someone in this thread was having this problem. Anyways, so if you want to align L and R channels, 1st run the timing signal and sweep signal through your reference speaker to have the reference measurement. Then, turn on the 2ns speaker, keep the reference signal on the reference speaker and simply change the output channel to the other one. Using your ears, verify that that is actually happening.

- Once I aligned the mids, the tricky part was to align the tweeters to the mids. I had to use the opposite side as reference to align the tweeter. So, for the right tweeter, I had to use the left mid as reference speaker.

- Once I took the measurement, I was not sure which peaks to align. The tallest peaks which come 2-3 cycles after the initial or the very initial peak which was smaller and may just be initial distortion? I did not have this problem with my mids. The tweeters didn't give me a very clean reading. I may have to redo this.

The mids staging is very good now. Bass moved to the front, but overall I think I lost some dynamics in higher frequencies. I think I need to redo the tweeters.


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## banshee28 (Mar 23, 2006)

Ziggyrama said:


> The way it works is that REW sends a chirp 1st through the reference speaker and then it runs a sweep using the speaker to be aligned to measure the IR relative to the chirp (your reference speaker). This is very important since if you don't get the chirp and sweep to go our the correct driver, you will either get the wrong values or you will see TA have no effect on your measurements. I believe someone in this thread was having this problem. Anyways, so if you want to align L and R channels, 1st run the timing signal and sweep signal through your reference speaker to have the reference measurement. Then, turn on the 2ns speaker, keep the reference signal on the reference speaker and simply change the output channel to the other one. Using your ears, verify that that is actually happening.


Yes, I was having an issue and it sounds like the L/R as you describe could be the issue. I had a feeling this could be the cause but have not had time to validate further. I have a stereo 3.5mm y adapter to RCA, but when I did a simple Pink Noise Signal Generator test using REW, output only RIGHT channel and DSP only routing LEFT to LEFT midrange, I got output!
I will have to re-check this but I think this may be the issue. Without laptop, all my Left Channels are on the left side and right is all right.


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## naiku (May 28, 2008)

Finally got around to giving this a shot today, started with my right mid as that is furthest. Got to this point:



forty5cal1911 said:


> Change routing in your DSP to Left channel -> Left Midbass
> Unmute the Left Midbass Output Channel in DSP


And no further. When I moved the Left Channel in the IO matrix to my Left Mid (so Front R 100% = Right Mid, Front L 100% = Left Mid) and I click measure. I get no sound at all. The only way I could get any sound is if I used both L and R inputs (50% on each) which is not going to work. 

Yes, I made sure to un-mute the Left Mid channel. Do I leave the reference speaker, in my case the right midrange un-muted? So when measuring Left midrange, both L and R should be unmuted? That's about the only thing I can think that I did wrong. Any idea on where I went wrong?


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## forty5cal1911 (Sep 11, 2006)

naiku said:


> Finally got around to giving this a shot today, started with my right mid as that is furthest...
> Do I leave the reference speaker, in my case the right midrange un-muted?


Yes leave the right mid un-muted.



naiku said:


> Any idea on where I went wrong?


Make sure both left and right mids are not muted. Also, make sure the Low Pass xover is bypassed in the DSP.

I take it your first Reference Measurement on your right mid completed successfully? Meaning you heard the timing chirp and then the tone following it and the corresponding measurement was displayed in REW?

If so your channel routing in REW and your DSP seem to be correct.

When you ran the measurement for the left mid did you hear the reference signal (timing chirp) come out of the right mid but no tone on the left?

The most important thing here is to understand what you are doing with this procedure and not just following steps. Ziggy did a great job of summarizing what is taking place using this measurement method.



Ziggyrama said:


> The way it works is that REW sends a chirp 1st through the reference speaker and then it runs a sweep using the speaker to be aligned to measure the IR relative to the chirp (your reference speaker). This is very important since if you don't get the chirp and sweep to go our the correct driver, you will either get the wrong values or you will see TA have no effect on your measurements. I believe someone in this thread was having this problem. Anyways, so if you want to align L and R channels, 1st run the timing signal and sweep signal through your reference speaker to have the reference measurement. Then, turn on the 2ns speaker, keep the reference signal on the reference speaker and simply change the output channel to the other one. Using your ears, verify that that is actually happening.


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## naiku (May 28, 2008)

Will try later with both unmuted. Yes the right mid worked perfectly, heard the chirp, then the tone. When moving to the left mid I hear nothing, no chirp or tone, in fact nothing even when clicking check levels. All crossovers bypassed in the DSP software.

Hopefully it's just needing the right mid not muted at the same time. Everything else looks set as it should be.


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## forty5cal1911 (Sep 11, 2006)

subterFUSE said:


> An ideal tuning process for me would be this:
> 
> 1. TA by IR/ETC.
> 2. EQ individual drivers flat.
> ...


Hey subterFUSE quick question for you, when using phase plot to align sub to mains - I am looking for the earliest (in time domain) delay that aligns phase at the acoustic cross over point between sub and midbass. Is that correct?

Thanks brother!


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## subterFUSE (Sep 21, 2009)

The driver with the steeper phase plot is the one that is late. So add delay to the shallower plot to make it steeper. When they are parallel then the timing is correct. You want them to be parallel and overlap so you might need to invert polarity on the sub if you are parallel but out by 180 degrees.


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## bnae38 (Oct 3, 2015)

Delay will change the phase slope? I thought it would only shift it.. an apf could change the slope?

Sry if stupid q. I'm probably off base..


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## subterFUSE (Sep 21, 2009)

bnae38 said:


> Delay will change the phase slope? I thought it would only shift it.. an apf could change the slope?
> 
> Sry if stupid q.


Yes, adding delay makes the phase slope steeper.


It's a lot easier to see when you are using a real-time Dual FFT software like SysTune or Smaart. You can literally be playing pink noise and hit the delay button on your DSP and watch the phase plot get steeper as you add delay.


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## bnae38 (Oct 3, 2015)

Ok got it.

But you'll smear arrival times if using ta to align slopes, correct?


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## bnae38 (Oct 3, 2015)

Assuming, that is, ir matching is done in each drivers passband.. ?

Edit: sorry don't wanna muddle this up, just trying to connect the dots in my mind.


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## subterFUSE (Sep 21, 2009)

bnae38 said:


> Ok got it.
> 
> But you'll smear arrival times if using ta to align slopes, correct?



Potentially. It sort of depends on how much we are off by, and how much we are trying to force the crossover alignment by timing vs. using order and frequency.

Generally, I would set timing to be in the ballpark based on distance or IR/ETC.

Then work on picking a set of filters to get the crossover alignment as good as we can without using additional timing. If we get to a point where we can't get the phase slopes parallel in the area of interest, then I would look at APF or Delay. If the slopes are parallel but not overlapping, then look at using a polarity invert and see if that shifts the plots to overlap.


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## subterFUSE (Sep 21, 2009)

You're never going to have perfect IR unless you have crazy FIR filtering going on.


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## bnae38 (Oct 3, 2015)

Imo, fir is the point of going off the deep end 

I have no intention of going there. 

Thanks for the info, good stuff.


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## forty5cal1911 (Sep 11, 2006)

So here's a quick measurement I just ran on Sub and Midbass phasing.










So I've currently go the sub lp at 73 and the midbass hp at 70 which accounts for the small differential between phase wrap. (Will be changing that to 70 on the sub)

Looks pretty good to me? Not a lot of phase separation until you get to very low freq. about 90 deg at 35. Thoughts?


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## bnae38 (Oct 3, 2015)

I have no idea .

Mb definitely on a steeper slope fwiw. (Once you unwrap it)


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## bnae38 (Oct 3, 2015)

Hmm low side out of passband, looks like a normal thing for phase slope to be steeper. My midrange does the same thing (looking at old measurements)...


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## Ziggyrama (Jan 17, 2016)

I gave this method a second try since I was not happy with my tweeter alignment. I did redo my left mid/right mid alignment too and I found that this method seems to be producing inconsistent results:

- I started by capturing my left mid as the reference driver since I aligned it to my sub.
- then I took a measurement on my right mid multiple times, around 10 times, and got very different timing each time. One time it was very close to my left mid (I already have TA set in the ball park), other times it was arriving early by various amounts.
- I am very confident I got my reference signal coming from the right driver, all other drivers muted on the DSP.
- I also spent the last few days listening to my initial TA settings, derived with REW, and the results are not very good. The sound is off, the staging is worse, it's very narrow and sunk in the dash, not very dynamic.

So, after taking a few tries and getting inconsistent readings, I decided to go back to HOLMImpulse. Note, I aligned my sub and the mids using HOLM and the results are excellent. The bass became omnidirectional, the mid bass blends very well, very cohesive. Also, I went back and remeasured and got the same results as before. HOLM is giving me very consistent results while REW is not. I decided to also do mids and tweeters using HOLM. I will report back once I have a couple of days of listening time.

To summarize, I don't trust this method based on my experience. The readings using the mic are too inconsistent and my ears are also saying the same thing.

If anyone is interested, I can post how to capture IR using HOMLImpulse. The sub alignment is described here:

http://www.diysubwoofers.org/misc/holmimpulse/ta.html


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## oabeieo (Feb 22, 2015)

Ziggyrama said:


> I gave this method a second try since I was not happy with my tweeter alignment. I did redo my left mid/right mid alignment too and I found that this method seems to be producing inconsistent results:
> 
> - I started by capturing my left mid as the reference driver since I aligned it to my sub.
> - then I took a measurement on my right mid multiple times, around 10 times, and got very different timing each time. One time it was very close to my left mid (I already have TA set in the ball park), other times it was arriving early by various amounts.
> ...


I see a lot of these kinds of how to set your TA threads and there good and informative. I like this one because it shows a new use of rew that is usabale. 

However, I think your description is tell tale of why some reflections should be used as the fundamental. Comb filtering is not going away and we need to use it to our advantage....meaning some drivers especially in a 4way should be using the 1st comb filter to steer the image with TA. This all depends where u speakers are, what speakers crossover etc etc ....only your ears will tell you when it's right. Your ears are the most sensitive piece of equipment you have to help you get it right. 


So I'm not against these TA threads , in some ways it's helpful. But sometimes it takes a bit more than just TA to make a good correction.


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## subterFUSE (Sep 21, 2009)

forty5cal1911 said:


> So here's a quick measurement I just ran on Sub and Midbass phasing.
> 
> 
> 
> ...




Actually, this is not great alignment.

You want the phase plots to be parallel and overlapping. Your subwoofer needs more delay to steepen the phase slope, and it might need to be inverted, too. Anything 90 degrees or more out is going to cause audible problems.


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## forty5cal1911 (Sep 11, 2006)

Ziggyrama said:


> I gave this method a second try since I was not happy with my tweeter alignment. I did redo my left mid/right mid alignment too and I found that this method seems to be producing inconsistent results:
> 
> So, after taking a few tries and getting inconsistent readings, I decided to go back to HOLMImpulse. Note, I aligned my sub and the mids using HOLM and the results are excellent. The bass became omnidirectional, the mid bass blends very well, very cohesive. Also, I went back and remeasured and got the same results as before. HOLM is giving me very consistent results while REW is not. I decided to also do mids and tweeters using HOLM. I will report back once I have a couple of days of listening time.
> 
> ...


HolmImpulse is a great program and the method outlined on Brian's site will work fine if you are using an external usb sound card and an analog Mic. 

This thread is for those who want to use their existing USB Mic with their on board sound card and get as accurate results as possible. The only way to do that is with an "Audible Timing Reference."

The problem with Holm is that when using a USB mic it CANNOT be time locked to the output device. This results in time drift between measurements and can be repeatably demonstrated. This has been discussed at length on the partsexpress forums and several blogs.

HOLM Impulse - Timelock, creeping offset??


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## forty5cal1911 (Sep 11, 2006)

subterFUSE said:


> Actually, this is not great alignment.
> 
> You want the phase plots to be parallel and overlapping. Your subwoofer needs more delay to steepen the phase slope, and it might need to be inverted, too. Anything 90 degrees or more out is going to cause audible problems.
> 
> ...


Thanks for the help man. I briefly played with it a bit this evening and could not get the phase slope steepened really at all. I'm going to do some more extensive experimentation to see what I can come up with.


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## subterFUSE (Sep 21, 2009)

forty5cal1911 said:


> Thanks for the help man. I briefly played with it a bit this evening and could not get the phase slope steepened really at all. I'm going to do some more extensive experimentation to see what I can come up with.



I'm less familiar with doing this on REW because I have not used that program in more than a year. It's so much easier when you can read phase in real-time with pink noise. But REW can't do that.

Did you shift your impulse responses equally back towards the zero time marker? This is a really important step before comparing phase of 2 drivers.
You need to measure each driver by itself, and then look at the IR. The driver that has the earlier IR starting peak, you should look at the time where that peak starts. You need to then shift BOTH of the IRs by that same amount of time. This will clean up the phase reading by removing any excess phase wraps.

Remember that we are only interested in the phase where the 2 speakers will be playing at approximately the same level. So, the crossover region in other words. Once you have 1 speaker playing 6-10dB loud than the other one, the phase becomes less important as 1 driver dominates.

But in the image above your crossover point was about 70 Hz, but by 40 Hz you were already significantly out of phase and that would probably cause issues.

If you can get the timing better between the drivers, you'll get those phase plots more on the same angle. And then it might require a polarity invert on the sub to get the traces to overlap.


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## Elektra (Feb 4, 2013)

It's would be great if someone can upload a video on YouTube or something... lol 


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## naiku (May 28, 2008)

forty5cal1911 said:


> Yes leave the right mid un-muted.


Think this was my problem, with both un-muted I got chirps and tones. However, for some reason after going through and lining the responses up the stage was all kinds of messed up. Everything pulled way way left. 

So I tried again and for some reason then the responses were not even close. Something seemed to be not quite right though, either with settings or equipment (laptop, microphone). The numbers on the scale were acting weird, I would get something like 3.2m on the first crosshair and -900u on the second. Instead of my left mid arriving before the right mid, it was showing as after etc. 

I was using a different laptop this time, so am hoping I just missed something. For now I went back to manually measuring and will try again.

Edit: Read through the thread again and I am having the same issues as ziggyrama. One measurement will be close, I can change nothing or make a very minor change, measure again and it's way off. It had me questioning if I had the reference speaker correct, making sure left and right was correct etc before I gave up. At least I am not the only one with the same issue. I am running win 10, Dayton umm6 microphone with realtek high definition audio listed as the sounds card.


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## sqnut (Dec 24, 2009)

Yes changing timing will affect the response, but I'm totally against using TA to correct response issues, one has an eq and slopes for that. Ta is only for arrival times and if that is off, then no amount of eq will get it to sound right.


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## Ziggyrama (Jan 17, 2016)

naiku said:


> Think this was my problem, with both un-muted I got chirps and tones. However, for some reason after going through and lining the responses up the stage was all kinds of messed up. Everything pulled way way left.
> 
> So I tried again and for some reason then the responses were not even close. Something seemed to be not quite right though, either with settings or equipment (laptop, microphone). The numbers on the scale were acting weird, I would get something like 3.2m on the first crosshair and -900u on the second. Instead of my left mid arriving before the right mid, it was showing as after etc.
> 
> I was using a different laptop this time, so am hoping I just missed something. For now I went back to manually measuring and will try again.


I think you're seeing what I was seeing, which is inaccurate measurements, all other things being equal. I don't know what the issue is but IMO this method is not reliable. If you think about it, the timing of the control signal is also subject to your laptop's hardware timing and software timing. I assume it sends a control signal, it times the response, which includes the latency of your laptop and all of it's inner workings, uses that as a reference for the channel you're trying to align. If that is the case than this method is also subject to the same flaws that Holm is, using the USB mic.



> HolmImpulse is a great program and the method outlined on Brian's site will work fine if you are using an external usb sound card and an analog Mic.
> 
> This thread is for those who want to use their existing USB Mic with their on board sound card and get as accurate results as possible. The only way to do that is with an "Audible Timing Reference."
> 
> ...


The latency creep is a real issue with using the USB mic for measuring IR but if you read that thread carefully, you'll find that some people have had success with that method. I am one of those people. I have gone back and reverified my measurements and they haven't changed across multiple days and during my tuning session. I believe the variance in results comes from the hardware people are using and possibly some settings in Holm. I am using a high end laptop with lots of computing power which makes the software scheduler very consistent. Consider the variation in different hardware people have, the drivers that are used and what is going on in the OS at the time you're taking the measurements. Holm does attempt to stabilize the latency by keeping the same channel open across multiple measurements.

Bottom line is, the acoustic reference is not reliable IMO. I have repeated the exact same measurement procedure, 10 iterations and 5 different results. I am using a tripod so the mic placement is identical every time. I am also trusting my ears to tell me if the settings are right. After dialing in the TA derived by REW, the overall sound quality degraded noticeably. That alone is a deal breaker for me.

I encourage the folks that are trying this method to make several runs and compare results. Take the same measurement 10 times, are you getting the same results every time? Then vote with your ears and see if you like the results. If you do, fantastic. Please go into this with eye wide open.


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## Babs (Jul 6, 2007)

subterFUSE said:


> Actually, this is not great alignment.
> 
> You want the phase plots to be parallel and overlapping. Your subwoofer needs more delay to steepen the phase slope, and it might need to be inverted, too. Anything 90 degrees or more out is going to cause audible problems.
> 
> ...


It's starting to click a bit how a phase plot along with IR on screen together in Smaart work together to show time domain arrival time and phase relationships. I have GOT to get that stupid cable built so I can get transfer function rolling. Getting the new DSP fired up on all cylinders. Of course I need to trace a wire or two for channels.


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## subterFUSE (Sep 21, 2009)

That's why I always argue people should not be getting these USB microphones. A real audio interface with XLR mics is the way to go, both for performance and for future-proofing yourself if you do ever decide to move up from REW to a more robust software.


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## subterFUSE (Sep 21, 2009)

Elektra said:


> It's would be great if someone can upload a video on YouTube or something... lol


One of these days I will do it, but not in REW.


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## forty5cal1911 (Sep 11, 2006)

subterFUSE said:


> That's why I always argue people should not be getting these USB microphones. A real audio interface with XLR mics is the way to go, both for performance and for future-proofing yourself if you do ever decide to move up from REW to a more robust software.
> 
> 
> Sent from my iPhone using Tapatalk


Yeah I am coming to the same conclusion after downloading the Smaart v8 demo. Looks like for any of the more robust software packages you have to be using a hardware loopback and XLR mic. So i can't see phase data in realtime in Smaart either.


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## Ziggyrama (Jan 17, 2016)

subterFUSE said:


> That's why I always argue people should not be getting these USB microphones. A real audio interface with XLR mics is the way to go, both for performance and for future-proofing yourself if you do ever decide to move up from REW to a more robust software.
> 
> 
> Sent from my iPhone using Tapatalk


You do have a valid point. By far the best method is to use the loopback as timing reference. I may just splurge and get the proper setup. That requires an XLT mic, the audio input box and a good soundcard. The last one is where I am hung up. Any recommendations?


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## forty5cal1911 (Sep 11, 2006)

Ziggyrama said:


> If that is the case than this method is also subject to the same flaws that Holm is, using the USB mic.
> 
> Bottom line is, the acoustic reference is not reliable IMO. I have repeated the exact same measurement procedure, 10 iterations and 5 different results. I am using a tripod so the mic placement is identical every time. I am also trusting my ears to tell me if the settings are right. After dialing in the TA derived by REW, the overall sound quality degraded noticeably. That alone is a deal breaker for me.
> 
> I encourage the folks that are trying this method to make several runs and compare results. Take the same measurement 10 times, are you getting the same results every time? Then vote with your ears and see if you like the results. If you do, fantastic. Please go into this with eye wide open.


I think I'm in agreement here. This seems to be very dependent on your platform. For me Holm gives inconsistent results much like what is described in the partexpress forum (the longer I wait between measurements the more skewed it becomes).

However, with REW and the audible timing reference I have had consistent results across at least 6 different sessions and several weeks. Most telling of all is that the results are good by ear and the measured delays are not far off from tracerite. If you check yourself with tone and adjust the delay in the tw or midrange you can hear it go out of phase.

You hit the nail on the head that there is signal propagation delay introduced by the laptop and depending on your hardware and cpu and mem usage at the time you run the measurement it can and will impact the signal propagation.

No matter which you are using Holm or REW the FFT program needs to be the only thing running.


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## subterFUSE (Sep 21, 2009)

It depends on what your desires are....


If you just need a basic sound card to use 1 microphone, then you could find something great for about $100.


If you want a multichannel sound card for use with multiple mics on a software like Smaart or Systune, then you might be looking at $250+


I use THIS


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## Babs (Jul 6, 2007)

subterFUSE said:


> That's why I always argue people should not be getting these USB microphones. A real audio interface with XLR mics is the way to go, both for performance and for future-proofing yourself if you do ever decide to move up from REW to a more robust software.
> 
> 
> Sent from my iPhone using Tapatalk


Yeah picked up an ECM8000 specifically for the purpose. For sake of just FR stuff, the UMIK directly into my laptop, literally in lap, is way too darn convenient. However once I get dialed in with a mic pre rig outside the car, that'll be moot.


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## Ziggyrama (Jan 17, 2016)

subterFUSE said:


> It depends on what your desires are....
> 
> 
> If you just need a basic sound card to use 1 microphone, then you could find something great for about $100.
> ...


How do you feed that into computer audio input?


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## subterFUSE (Sep 21, 2009)

Ziggyrama said:


> How do you feed that into computer audio input?


It's a USB sound card.

Microphones plug into the front XLR ports.

On the back it has RCA ports and 1/4" ports.


I run RCA out and into my car. This carries the test signal.
I run a 1/4" from an output directly into an input for the reference signal.

I can even run an RCA from the DSP into an input on the Tascam so that I can measure the transfer functions of the electrical filter output from the DSP.


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## forty5cal1911 (Sep 11, 2006)

subterFUSE said:


> Did you shift your impulse responses equally back towards the zero time marker? This is a really important step before comparing phase of 2 drivers.
> You need to measure each driver by itself, and then look at the IR. The driver that has the earlier IR starting peak, you should look at the time where that peak starts. You need to then shift BOTH of the IRs by that same amount of time. This will clean up the phase reading by removing any excess phase wraps.
> 
> Remember that we are only interested in the phase where the 2 speakers will be playing at approximately the same level. So, the crossover region in other words. Once you have 1 speaker playing 6-10dB loud than the other one, the phase becomes less important as 1 driver dominates.
> ...


Got this tracking a little better tonight. I did calculate the IR offset but I had a stinkin' high pass filter at 25 that was throwing some phase shifts on the low end. Haven't listened to it yet but will get a chance tomorrow. I'm a little worried about possible cancellation in the 75-85 region but we'll see.

Thanks again for the pointers subterFUSE!


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## Babs (Jul 6, 2007)

subterFUSE said:


> It's a USB sound card.
> 
> 
> 
> ...



Yeah enough free ins and outs is the key. I gotta do a little finagling with that for sending to system and the loop reference. Best I can tell it's something like this I drew up. 









At this point I'm not opposed to upgrading the interface to make the whole business cleaner. 


Sent from my iPhone using Tapatalk Pro


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## Mlarson67 (Jan 9, 2015)

Just wanted to report my finding don this method for TA. After doing this method several times to where I was happy with the results, I am super pleased with the results. Letting my ears be the guide, I used this setup for the last two weeks. The best my system has sounded yet. Stage and imaging are spot on. My only problem now is aligning the sub with the mid-bass. Seems as thought the bass is upfront most of the time but pulls to the back sometimes.
Does anyone have a method of using Rew to do this?


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## forty5cal1911 (Sep 11, 2006)

Mlarson67 said:


> Just wanted to report my finding don this method for TA. After doing this method several times to where I was happy with the results, I am super pleased with the results. Letting my ears be the guide, I used this setup for the last two weeks. The best my system has sounded yet. Stage and imaging are spot on. My only problem now is aligning the sub with the mid-bass. Seems as thought the bass is upfront most of the time but pulls to the back sometimes.
> Does anyone have a method of using Rew to do this?


Thanks for posting your results.

I have a method for performing this and I've got to give the credit to subterFUSE for putting me on the right track. You can see my before and after phase plots in the last page or two of this thread. I will put together a post detailing how to get there. I've got to say once I got TA aligned properly with IR and got the phase between sub and mb dialed in..... man it's spectacular! Amazing how much getting phase alignment between sub and midbass tightens everything up including even the perception in midrange.


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## Elektra (Feb 4, 2013)

forty5cal1911 said:


> Thanks for posting your results.
> 
> 
> 
> I have a method for performing this and I've got to give the credit to subterFUSE for putting me on the right track. You can see my before and after phase plots in the last page or two of this thread. I will put together a post detailing how to get there. I've got to say once I got TA aligned properly with IR and got the phase between sub and mb dialed in..... man it's spectacular! Amazing how much getting phase alignment between sub and midbass tightens everything up including even the perception in midrange.




That would be awesome if you can post your method... 

Some of us have been around for decades in the game but when it comes to using a program like REW we are complete newbies...

So please when sharing your method remember "newbies" are trying to follow your method so make it as easy as possible to follow..

Shot! 


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## Ziggyrama (Jan 17, 2016)

Mlarson67 said:


> Just wanted to report my finding don this method for TA. After doing this method several times to where I was happy with the results, I am super pleased with the results. Letting my ears be the guide, I used this setup for the last two weeks. The best my system has sounded yet. Stage and imaging are spot on. My only problem now is aligning the sub with the mid-bass. Seems as thought the bass is upfront most of the time but pulls to the back sometimes.
> Does anyone have a method of using Rew to do this?


Can you post details of what you did? Specifically, which driver did you use as reference, which driver did you align to that reference, what frequencies did you use for the alignment, what hardware and software are you using (mic and OS)?

I really want this method to work but my last 2 tries failed due to big variation in measured IR. I'd like compare your method and hopefully something will stand out at me. Thanks.


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## Mlarson67 (Jan 9, 2015)

I used the exact method that was laid out. I used my right midbass as my reference at 1k. I then aligned the left midbass to it. I then aligned both midranges to it. 
There were some discrepancies with aligning them though. After measuring and adjusting according to the differences in the rise at IR. They didn't align perfect. I just kept tweaking the adjustments and remeasuring until they we spot on.

I then aligned both tweeters to the right midbass as well. Following the same procedure as before.

After I was happy with those alignments I switched to 2.5k and used my right midbass as reference as well. Repeating the same procedure as above. Measure adjust and so on until the first peak in the IR was aligned.

Ziggyrama I am using the soundcard on my laptop and a UMIK usb mic.

I will say that aligning the tweeters was by far the most difficult and time consuming. I had to measure and adjust about five times to get it right


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## HCWLSU101 (Apr 30, 2009)

I am assuming there is no way to use this feature with a USB mic if using a dsp without input routing ability. I am using a bit ten through aux and can't assign inputs - to my knowledge


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## 156546 (Feb 10, 2017)

Best to turn off the low pass filter for the midbass when you're using it as a timing reference.


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## forty5cal1911 (Sep 11, 2006)

HCWLSU101 said:


> I am assuming there is no way to use this feature with a USB mic if using a dsp without input routing ability. I am using a bit ten through aux and can't assign inputs - to my knowledge


Since you only have overall left and right channel routing you can use the output channel mute function to isolate the two drivers you are aligning. You will have to change your acoustic reference from right to left as you go through the driver sets. Once you get your left midbass IR aligned you can use it as the reference to align your right midrange or tweeter and vice versa.

Hope that makes sense.


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## cadeet (Apr 15, 2016)

Has anyone seen this yet? https://www.minidsp.com/applications/auto-eq-with-rew/measuring-time-delay


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## Babs (Jul 6, 2007)

cadeet said:


> Has anyone seen this yet? https://www.minidsp.com/applications/auto-eq-with-rew/measuring-time-delay


Pretty good write-up.. I didn't realize the info in the plot will tell you the delay amount. 

Reference driver:









Other driver compared in time to reference:


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## banshee28 (Mar 23, 2006)

cadeet said:


> Has anyone seen this yet? https://www.minidsp.com/applications/auto-eq-with-rew/measuring-time-delay


I just tried this but I think I am running into the same issues. It seems like the measurement output always goes out BOTH speakers even though I set it either Left or Right in the drop down in the Measurement screen before measuring.
In Preferences section I should have it set to BOTH, right? If so maybe thats my issue. I do have a Stereo 3.5mm Y-adapter going to 2 RCA's on the DSP.


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## cadeet (Apr 15, 2016)

Not sure which dsp you're trying to do t/a with. Let's first physically find what the furthermost driver is in the vehicle. I don't know your setup, but lets assume you have rear speakers, the rear right would be you furthermost. What's the input for this channel? Let's assume it's input 2. This input is going to be your timing reference. So your output in preferences should be setup to output to "2" & your timing reference is going to be "2".
You then would mute all channels except for that channel. Take your timing reference. Now, you want to measure your system. To do that, now you would output from channel "1" (you're timing channel is not going to change from channel "2" for ALL you're measurement's). Leave you're timing channel unmuted & now unmute a channel you want to measure. Note: You now have to route all channels you want to measure to channel "1" because channel "2" wil be used strictly for the timing reference.


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## cadeet (Apr 15, 2016)

So after reading this thread & two others, I'm starting to grasp the concept and will get out & try the method outlines. However, the only thing I'm not 100% on is the frequency response that needs to be generated for the speaker we want to match to the reference. Is that really important? Do we need to take a full response or just capture say 3000-4000 for example.


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## cadeet (Apr 15, 2016)

Ziggyrama said:


> I think you're seeing what I was seeing, which is inaccurate measurements, all other things being equal. I don't know what the issue is but IMO this method is not reliable. If you think about it, the timing of the control signal is also subject to your laptop's hardware timing and software timing. I assume it sends a control signal, it times the response, which includes the latency of your laptop and all of it's inner workings, uses that as a reference for the channel you're trying to align. If that is the case than this method is also subject to the same flaws that Holm is, using the USB mic.
> 
> 
> 
> ...


I attempted to perform t/a using this the method & numbers were all over the place. It's very unreliable & I can't vouch for this method. Not sure what's going on. I'm on the latest beta, a high Lenovo that's up to date, & using the UMK-1. I was also using battery power. Thought about hooking up an inverter, but figured that would introduce more noise into the laptop. I'm at a loss.


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## forty5cal1911 (Sep 11, 2006)

cadeet said:


> I attempted to perform t/a using this the method & numbers were all over the place. It's very unreliable & I can't vouch for this method. Not sure what's going on. I'm on the latest beta, a high Lenovo that's up to date, & using the UMK-1. I was also using battery power. Thought about hooking up an inverter, but figured that would introduce more noise into the laptop. I'm at a loss.


Make sure your Low Pass filters for both your midbasses are disabled, bypass all EQ and make sure no TA is configured in your dsp. 

Turn off any Audio enhancements in Windows. IE - Dolby DSP processing, etc. Minimize any programs running in memory in Windows.

Follow the instructions in the first post to the T.

First measurement will be a timing chirp from the right midbass followed by the sweep from the right midbass.

Next measurement will be a timing chirp from the right midbass followed by the sweep from the left midbass.

Take your time and double check everything you'll get it.


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## Ziggyrama (Jan 17, 2016)

forty5cal1911 said:


> Make sure your Low Pass filters for both your midbasses are disabled, bypass all EQ and make sure no TA is configured in your dsp.
> 
> Turn off any Audio enhancements in Windows. IE - Dolby DSP processing, etc. Minimize any programs running in memory in Windows.
> 
> ...


While reading your post, another idea popped into my head. I have a Lenovo yoga laptop sitting around that I was planning to rebuild using latest Fedora. Perhaps I should repeat the procedure using Linux and see if the results are different. Linux OS has a much more robust scheduler so if OS is playing a role in producing inconsistent results, I may get better results this way. Let us not forget, we are aiming for high precision, accuracy down to 0.1ms so little details matter. I will report back on results when I have them.

FYI, the settings Holm gave me are very close. I did final tuning by ear but it got me to within 0.3ms of where I think it should be. Bass from the sub in the trunk blends seamlessly with the front mid bass.


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## Babs (Jul 6, 2007)

Ziggyrama said:


> While reading your post, another idea popped into my head. I have a Lenovo yoga laptop sitting around that I was planning to rebuild using latest Fedora. Perhaps I should repeat the procedure using Linux and see if the results are different. Linux OS has a much more robust scheduler so if OS is playing a role in producing inconsistent results, I may get better results this way. Let us not forget, we are aiming for high precision, accuracy down to 0.1ms so little details matter. I will report back on results when I have them.
> 
> FYI, the settings Holm gave me are very close. I did final tuning by ear but it got me to within 0.3ms of where I think it should be. Bass from the sub in the trunk blends seamlessly with the front mid bass.



I've never been able to time in sub with IR. I imagine though if you run high-pass bypassed I don't see why it wouldn't be accurate for arrival time. One thing about mine is two 12" drivers behind the back seat. I'll bet there's significant distance delta between all that cone area. Might be fun to time them separately and assess. 


Sent from my iPhone using Tapatalk Pro


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## forty5cal1911 (Sep 11, 2006)

Ziggyrama said:


> While reading your post, another idea popped into my head. I have a Lenovo yoga laptop sitting around that I was planning to rebuild using latest Fedora. Perhaps I should repeat the procedure using Linux and see if the results are different. Linux OS has a much more robust scheduler so if OS is playing a role in producing inconsistent results, I may get better results this way. Let us not forget, we are aiming for high precision, accuracy down to 0.1ms so little details matter. I will report back on results when I have them.
> 
> FYI, the settings Holm gave me are very close. I did final tuning by ear but it got me to within 0.3ms of where I think it should be. Bass from the sub in the trunk blends seamlessly with the front mid bass.


Agreed Ziggy. What a great idea bro!
I would expect Linux to give a much better baseline as the OS kernel has will have so much less service (daemons in this case) interference and background processing going on. May even be worth slapping a Ubuntu live cd in and installing REW in the session to see how it measures.


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## forty5cal1911 (Sep 11, 2006)

Babs said:


> I've never been able to time in sub with IR. I imagine though if you run high-pass bypassed I don't see why it wouldn't be accurate for arrival time. One thing about mine is two 12" drivers behind the back seat. I'll bet there's significant distance delta between all that cone area. Might be fun to time them separately and assess.


I used the phase alignment method recommended by SubterFUSE and have gotten great results. Same as Ziggy, midbass and sub blend perfectly, impact is all in the front and most of the time I cannot localize the sub.

I've been meaning to post the procedure I used using REW just haven't had the time. It's dead simple though if you're using a DSP that has 11.25 degree sub phase increments.


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## cadeet (Apr 15, 2016)

forty5cal1911 said:


> Make sure your Low Pass filters for both your midbasses are disabled, bypass all EQ and make sure no TA is configured in your dsp.
> 
> Turn off any Audio enhancements in Windows. IE - Dolby DSP processing, etc. Minimize any programs running in memory in Windows.
> 
> ...


I think I've made some progress. When I first attempted to perform the t/a, it was via hdmi out to my Pioneer 4100. I was unsuccessful in getting consistent results. This time I bypassed the pioneer & ran rca's to my c-dsp. While I did get anomaly readings ever now & then, the results where better. I think I've got it dialed in, but I'm not sure about the t/a of my tweeters. If someone has a few minutest to review what I achieved & see if I'm on the right track I would appreciate it. I'm attaching a link to download my mdat file for reviewing. https://1drv.ms/u/s!Aokq7ddB0b3Jgf8VIa9e49kUHWxh4Q


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## cadeet (Apr 15, 2016)

Well since no response....here are my results with pics. How does this look?


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## Babs (Jul 6, 2007)

cadeet said:


> Well since no response....here are my results with pics. How does this look?


I'd say that's lookin' pretty good.


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## Ziggyrama (Jan 17, 2016)

@cadeet, how does it sound?


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## brumledb (Feb 2, 2015)

To me, it looks like the Left Tweet is out ~1.4ms and the Right ~2ms. Everything else looks good.




cadeet said:


> I think I've made some progress. When I first attempted to perform the t/a, it was via hdmi out to my Pioneer 4100. I was unsuccessful in getting consistent results. This time I bypassed the pioneer & ran rca's to my c-dsp. While I did get anomaly readings ever now & then, the results where better. I think I've got it dialed in, but I'm not sure about the t/a of my tweeters. If someone has a few minutest to review what I achieved & see if I'm on the right track I would appreciate it. I'm attaching a link to download my mdat file for reviewing. https://1drv.ms/u/s!Aokq7ddB0b3Jgf8VIa9e49kUHWxh4Q


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## Ziggyrama (Jan 17, 2016)

brumledb said:


> To me, it looks like the Left Tweet is out ~1.4ms and the Right ~2ms. Everything else looks good.


Are you thinking the initial peaks are driver distortion?


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## cadeet (Apr 15, 2016)

@Ziggyrama it sounds pretty centered, but the image is moving around more than I like. 
@brumledb arriving too early or late? As stated above, it sounds like they might be arriving a little early. I still need to do some eq'ing & level matching which is going to even-out some frequencies.


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## Babs (Jul 6, 2007)

cadeet said:


> @Ziggyrama it sounds pretty centered, but the image is moving around more than I like.
> @brumledb arriving too early or late? As stated above, it sounds like they might be arriving a little early. I still need to do some eq'ing & level matching which is going to even-out some frequencies.


If overall mono pink noise is centered between pairs (tweets, mids, etc), but the image is "moving around" that's a need for balance EQ. Make left=right in freq response. Then test by filtered pink noise (such as 1/3 octave pink noise) tracks to see spots up through the spectrum where the image is drifting or ghosting etc.


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## forty5cal1911 (Sep 11, 2006)

Cadeet good job looks pretty close!

Looks like the tweeters are out by just a hair.

Right Tweeter looks to need .12 ms more delay










Left Tweeter looks to need .06 ms more delay










Once you add that delay take a look at the ETC tab and select your Tweets and Reference MB. You should see the tweeter peaks below shifted closer to 0. (Actually in your measurement they should end up on .17)










Agree with Babs that you will still need to eq left to right for balance. Kyle's videos have a good walk through.


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## Ziggyrama (Jan 17, 2016)

I would level match the tweeters before you do more TA. Your settings are pretty close so the rest should be done by ear. And to do that, the levels need to be close or you will have a hard time hearing the TA changes. FWIW.


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## brumledb (Feb 2, 2015)

Ok, I went back and looked at this again and looks like each tweet needs to be delayed ~0.8ms. When aligning speakers (especially tweets to mids) you cannot use the peaks to align. You have to align the tweet to the where the slope of the first peak just begins to leave horizontal 0. I will attach a link at the bottom if you would like to read about this further.



[URL=http://s284.photobucket.com/user/brumledb/media/Time%20aligment/Screenshot%2026_zpsdicfyvoh.png.html][/URL]

[URL=http://s284.photobucket.com/user/brumledb/media/Time%20aligment/Screenshot%2027_zpssvvmfc7a.png.html][/URL]

[URL=http://s284.photobucket.com/user/brumledb/media/Time%20aligment/Screenshot%2028_zpsxyr2lotb.png.html][/URL]

[URL=http://s284.photobucket.com/user/brumledb/media/Time%20aligment/Screenshot%2029_zpsz1ljaurk.png.html][/URL]

Following up on this thread after spending a fair amount of time on the REW forums learning more about measuring delays via Impulse Response. Here are a few things I learned: 1. When measuring for TA via impulse response, it's important to only use 1 measurement sweep. I had my REW software performing 2 sweeps by default and this was causing some strange fluctuations in the IR readings. 2. You want to align the initial rise of the first peak in the IR, not the actual IR peak (i.e. the 100% mark). This was really confusing me, as you can tell in the post above. It had me thinking the midbass drivers were reading further away than my horns when that wasn't the case. Now that I'm aligning the initial rise, the timings are better and the passenger side horn is registering as farthest away as expected. Here is a pic of my latest IR alignment.  3. You can hold down CTRL and Right-Click then Drag to get the difference in time and distance calculated for you on screen. 4. You can use the Impulse tab Controls menu to add or subtract delay to the IR charts to visually align them and help confirm the correct amount of delay needed. This is kind of similar to using the manual EQ filters to match a house curve. You can test it out before applying it to your DSP.[/QUOTE]"]


subterFUSE said:


> Following up on this thread after spending a fair amount of time on the REW forums learning more about measuring delays via Impulse Response. Here are a few things I learned: 1. When measuring for TA via impulse response, it's important to only use 1 measurement sweep. I had my REW software performing 2 sweeps by default and this was causing some strange fluctuations in the IR readings. 2. You want to align the initial rise of the first peak in the IR, not the actual IR peak (i.e. the 100% mark). This was really confusing me, as you can tell in the post above. It had me thinking the midbass drivers were reading further away than my horns when that wasn't the case. Now that I'm aligning the initial rise, the timings are better and the passenger side horn is registering as farthest away as expected. Here is a pic of my latest IR alignment.  3. You can hold down CTRL and Right-Click then Drag to get the difference in time and distance calculated for you on screen. 4. You can use the Impulse tab Controls menu to add or subtract delay to the IR charts to visually align them and help confirm the correct amount of delay needed. This is kind of similar to using the manual EQ filters to match a house curve. You can test it out before applying it to your DSP.


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## oliverlim (Dec 5, 2016)

I am trying to get this to work on my setup. However my DSP which is audison AP 8.9 bit does not seem to allow assigning of inputs to its outputs. So I am at a loss how to use this method to TA my 3 way active setup. I am sure there is a easy way but I just cant seem to figure out how to route the test signal to each driver. 

Any tips or methods is most welcome


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## cadeet (Apr 15, 2016)

forty5cal1911 said:


> Cadeet good job looks pretty close!
> 
> Looks like the tweeters are out by just a hair.
> 
> ...


Excellent! It sounds pretty close, but as suggested I think level matching will allow me to make the tweaks you suggest & also begin to start tweaking by ear as well. Thanks for referencing each tweeter as it applies to my measurements, as now I understand what we're attempting to align to. With my lack of knowledge about the time domain & applying it to the interpretation to REW, it makes it somewhat difficult to understand what to align too. Thanks again bud. Getting back out today before it gets hot!


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## mbradlawrence (Mar 25, 2013)

thebookfreak58 said:


> Remember, align the peaks for high frequency drivers, align the rise (as it starts to go positive direction) for low frequency.


Makes sense with tweets to tweet, mid to mid, etc. But what about from mid to tweet, or woofer to mid?


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## subterFUSE (Sep 21, 2009)

Impulse response is only moderately useful for time alignment.

Phase alignment works much better for time aligning tweets to mids, and mids to midbass, and for subs.

Lately, I have been aligning the right side to each other, and the left side to each other and then grouping the whole right side together and left side together and then delay the group to center my image. Then I phase align the sub, and pretty much done.


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## naiku (May 28, 2008)

Funny seeing this thread bumped up again after a few months, I tried to use this method again today with my MiniDSP and still get the same inconsistent results. I can run the measurement and get say 0.5ms delay the first time, run it immediately again after and get 5ms delay.

@subterFUSE do you have any links to using phase alignment? Would be interested to learn a different method.


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## drop1 (Jul 26, 2015)

Itnwas asking about this the other day . Glad this popped up. 
Ta by ear ain't very hard. If the left and right channels are the same intensity and see eq'ed then you set the ta to set the vocal directly in front of you. Then traceright comes in handy to move the image over to the left.

What i want to ask is wouldn't this method also put the center of the image directly in front of You? If the left/right sides are equal intensity and eq'ed it seems like it would.
Do you just use tracerite from there to shift the image over?


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## Ziggyrama (Jan 17, 2016)

subterFUSE said:


> Impulse response is only moderately useful for time alignment.
> 
> Phase alignment works much better for time aligning tweets to mids, and mids to midbass, and for subs.
> 
> Lately, I have been aligning the right side to each other, and the left side to each other and then grouping the whole right side together and left side together and then delay the group to center my image. Then I phase align the sub, and pretty much done.


How are you doing phase alignment? Using REW and phase plot and aligning the plots? Can you explain more?

Sent from my VS986 using Tapatalk


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## Babs (Jul 6, 2007)

Ziggyrama said:


> How are you doing phase alignment? Using REW and phase plot and aligning the plots? Can you explain more?
> 
> Sent from my VS986 using Tapatalk


Subterfuse is using real time transfer function (Smaart or Systune) which allows real time visibility of phase slopes for comparison.. Measure and capture one, compare it to another (tweet vs mid for example), then in a Helix DSP, a driver phase can be adjusted incrementally. It's kind of sorta like TA fine adjustment, if that makes sense. You get it close with TA, then phase adjustment locks it in. REW will do this with sweeps, but dang you'll be there a while so pack a lunch. It's really not that bad, but it is iterative instead of real-time as you adjust. Measure adjust measure adjust.

Keep in mind though geometry when looking at top-end freq drivers.. You move your head back and forth and it goes in phase, out of phase, etc at certain frequency points because as you move an inch here or there, the distance to different drivers change but not at the same rate. Ain't car audio fun.


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## Babs (Jul 6, 2007)

subterFUSE said:


> Lately, I have been aligning the right side to each other, and the left side to each other and then grouping the whole right side together and left side together and then delay the group to center my image. Then I phase align the sub, and pretty much done.


Been thinking right along that same line for the next time I can actually play in the car.. Use IR to get pretty close, then phase to nail it, granted a grain of salt up top between tweets and mids and phase slope matching. But theoretically if you nail down each side independently, then left/right centering becomes pretty much what it is. We've had that conversation though about parallax and where's center supposed to be etc etc. I think it's the 2-ear thing.. If we had one ear, it'd be all about arrival time and IR. Wouldn't do us much good for stage perception though I suppose.


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## 156546 (Feb 10, 2017)

Based on arrival time (phase) and level matching, center is in between the two speakers, not in front of you. That's how it works.


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## 156546 (Feb 10, 2017)

Phase adjust in the Helix DSP is an all pass filter. Changing the "phase" in the UI changes the frequency of the all pass filter.


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## Babs (Jul 6, 2007)

GotFrogs said:


> Based on arrival time (phase) and level matching, center is in between the two speakers, not in front of you. That's how it works.



That's how I've been doing it.. Some folks have commented and one judge even suggested on my score it was too far to the right.. I think it's the illusion of my long sloping windshield, so directly between the drivers in pillars placed further back, it places the image directly between the drivers as expected. However it's perceived as right of center by line of sight when looking at the windshield. So on a longer dash and a windshield that's not as sloped, so drivers and windshield don't have as much delta, like John's Audi, it doesn't have as much of this optical illusion affect. 

The Frogs get it done for sure though. 


Sent from my iPhone using Tapatalk Pro


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## drop1 (Jul 26, 2015)

GotFrogs said:


> Based on arrival time (phase) and level matching, center is in between the two speakers, not in fro3nt of you. That's how it works.


A completely non timed system should be directly between the speakers.

If a signal is arriving at a person's ears at the exact same time, and the l/R channels are perfectly eq'ed and leveled
Each ear will receive exactly the same signal and it seems when that occurs we would perceive the sound to be directly in front of us.
I mean isn't reason for moving it in the first place a bandaid for having a squashed left stage?


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## 156546 (Feb 10, 2017)

drop1 said:


> A completely non timed system should be directly between the speakers.
> 
> If a signal is arriving at a person's ears at the exact same time, and the l/R channels are perfectly eq'ed and leveled
> Each ear will receive exactly the same signal and it seems when that occurs we would perceive the sound to be directly in front of us.
> I mean isn't reason for moving it in the first place a bandaid for having a squashed left stage?


Nope. Not how it works. If you like it better that way, then the fix is pretty simple. Set your delays with a tape measure or with impulse responses. Then, adjust the balance control to move the center to the left. Attempting to do that with delay will just add a bunch of comb filtering.


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## drop1 (Jul 26, 2015)

GotFrogs said:


> Nope. Not how it works. If you like it better that way, then the fix is pretty simple. Set your delays with a tape measure or with impulse responses. Then, adjust the balance control to move the center to the left. Attempting to do that with delay will just add a bunch of comb filtering.


It's not a matter of like it don't like. I tune with it center dash.
I always have.

What is throwing me off is human hearing part.
If we hear a sound with both ears EXACTLY the same in every way. Phase, intensity, frequency respose , everything, that sound should be directly in front of us.
For us to perceive sounds off center, to the side or behind us each ear must receive different Information.
Either slightly attenuated and diffuse on the far side ear , reflected or whatever. For us us to hear anything not directly in front of us the sounds reaching each ear must have not only differences in amplitude but time as well.


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## Babs (Jul 6, 2007)

drop1 said:


> It's not a matter of like it don't like. I tune with it center dash.
> I always have.
> 
> What is throwing me off is human hearing part.
> ...


The reality is, what we're effectively achieving in a car by having equal arrival times, balanced EQ and magnitude from all front-stage drivers is a stage with a center image equidistant from left/right drivers.. So that will end up at a point between the two drivers at the listening position. The problem occurs because the driver-seat listening position is not centered, so there is a compromise to be made somewhere.. While you're facing directly forward, the whole stage is rotated slightly to the right, even when aligned, because the left side drivers are closer to the 0 degree line directly in front of you.. Your "actual" center. Left is actually left-center, and right is actually extreme-right. 

Which is one reason a big S6 Audi (yes I'm picking on you Subterfuse ) is such a joy to listen to.. It's got a nice big stage that gives the impression of a bit more symmetrical left-to-right stage, than a smaller car with seat placement closer to the left side such as my Civic for example or a certain Mazdaspeed3 I recall with fondness. That said though, you can still achieve absolute greatness in stage in a small car like that, but you will also have to understand front-center-stage is going to be to the right a tad if you're going for perfect alignment and stage symmetry.

So while you can dial in a center that's directly zero degrees by TA compensation, you will have stretched your right stage and compressed your left stage. That of course is ok, if that's the preferable choice for you for center image placement. It's just not the typical norm for a stereo 1-seat tune, even in the typical competition rules etc.


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## drop1 (Jul 26, 2015)

Babs said:


> The reality is, what we're effectively achieving in a car by having equal arrival times, balanced EQ and magnitude from all front-stage drivers is a stage with a center image equidistant from left/right drivers.. So that will end up at a point between the two drivers at the listening position. The problem occurs because the driver-seat listening position is not centered, so there is a compromise to be made somewhere.. While you're 4facing directly forward, the whole stage is rotated slightly to the right, even when aligned, because the left side drivers are closer to the 0 degree line directly in front of you.. Your "actual" center. Left is actually left-center, and right is actually extreme-right.
> 
> Which is one reason a big S6 Audi (yes I'm picking on you Subterfuse ) is such a joy to listen to.. It's got a nice big stage that gives the impression of a bit more symmetrical left-to-right stage, than a smaller car with seat placement closer to the left side such as my Civic for example or a certain Mazdaspeed3 I recall with fondness. That said though, you can still achieve absolute greatness in stage in a small car like that, but you will also have to understand front-center-stage is going to be to the right a tad if you're going for perfect alignment and stage symmetry.
> 
> So while you can dial in a center that's directly zero degrees by TA compensation, you will have stretched your right stage and compressed your left stage. That of course is ok, if that's the preferable choice for you for center image placement. It's just not the typical norm for a stereo 1-seat tune, even in the typical competition rules etc.


I understand all of this . I was simply asking if all things being equal would this method center the image directly in front of you or center dash between the speakers. 
Logic says that the method should center the sound directly in front of the mic. 
I'm not in any way trying to place it there, I was just asking a question about the method.
For tuning the depth of my stage dictates to me how far I shift the image right.
If I'm working with a relatively shallow stage that sounds close the harder right I shift the stage if I have a nice deep stage I only need to shift it a little right of line of sight which puts the center center of the hood.
I think this is something often overlooked.
Having a shallow stage and not running the image far enough right is something I hear often. 
Not enough people pay attention to stage depth when It comes to centering the image.
In the end I was simply curious as to the outcome of this process. That's all.


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## Babs (Jul 6, 2007)

drop1 said:


> I understand all of this . I was simply asking if all things being equal would this method center the image directly in front of you or center dash between the speakers.
> 
> Logic says that the method should center the sound directly in front of the mic.
> 
> ...



Shallow stage I've found is more a function of not being well timed and phased and balanced in response. 

Understood.. I misunderstood you. Alignment will not place stage directly in front of you but directly between the two drivers being aligned as viewed from listening position. Mathematically it's a bit
More complex than that but essentially draw imaginary line between drivers.. Center aligned should be at a spot directly between. 


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## Ziggyrama (Jan 17, 2016)

Babs said:


> Shallow stage I've found is more a function of not being well timed and phased and balanced in response.
> 
> Understood.. I misunderstood you. Alignment will not place stage directly in front of you but directly between the two drivers being aligned as viewed from listening position. Mathematically it's a bit
> More complex than that but essentially draw imaginary line between drivers.. Center aligned should be at a spot directly between.
> ...


Indeed. This has been my result and I have to second this based on my results. Once I got the phase right and time aligned everything, the center is pretty much in the middle of my windshield, right where the rear view mirror is. The center sounds deep and high. As the sounds move to far left or right, they tend to move closer to me. I am in a left hand side car so my far left stage roughly ends around the A pillar. The right stage extends far and seem to go beyond the right A pillar. Overall, it does sound wide and expansive, all of this in a Subaru which isn't a very large car so Babs is definitely right on this. Now, here is the kicker. What has really extended my stage and made it sound larger is rear fill . But it is delayed by 22ms and L+R mono, which isnt ideal but fairly close.

Sent from my VS986 using Tapatalk


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## subterFUSE (Sep 21, 2009)

Ziggyrama said:


> But it is delayed by 22ms and L+R mono, which isnt ideal but fairly close.


Is there a reason you have not tried L-R for the rears?


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## Ziggyrama (Jan 17, 2016)

subterFUSE said:


> Is there a reason you have not tried L-R for the rears?


Yes, my DSP does not do L-R mixing. My current setup is what I can achieve with DSP and without doing additional rewiring. L-R requires me to do some wiring changes, on the RCAs which I just haven't gotten to yet. If I could do L-R on the DSP, I'd be there now.

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## drop1 (Jul 26, 2015)

This was my results from my system without adjusting the the ta . This is what I timed by ear. I just measured what I currently have . Am I missing something?


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## drop1 (Jul 26, 2015)

Ok again this is how my system is currently set up by ear.
I found the lower zoom. 
It's giving me numbers like 247u at the first peaks. What is that. Honestly is this far enough out to matter?

Currently with what you see I have a very good center image. Solid. Any adjustment to the ta, adding a ms to either channel diffuses the center and draws the sound to whatever speaker I'm adjusting. It smears the image badly. Kick drums are no longer under the rearview if I move outside of my current settings.
I had hoped that this was something that would benefit me but I'm not familiar with this technique. 
Both sides are eq'ed as close as I can get to being almost reflections of each other.


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## Babs (Jul 6, 2007)

drop1 said:


> Ok again this is how my system is currently set up by ear.
> 
> I found the lower zoom.
> 
> ...



Sounds like you're pretty darn dialed in. 
For fun and information flip over to ETC as well and take a look. It can give you a slightly better perspective on how the initial peaks line up. Keeping in mind your measuring with a single mic appropriately and when you actually listen you've got two ears approximating a center image, so don't let it puzzle you if there's some fine tuning your ears will tell you to do. Sounds like you've caught on to the combing and smearing that occurs when you over adjust one direction or another. 


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## drop1 (Jul 26, 2015)

Babs said:


> Sounds like you're pretty darn dialed in.
> For fun and information flip over to ETC as well and take a look. It can give you a slightly better perspective on how the initial peaks line up. Keeping in mind your measuring with a single mic appropriately and when you actually listen you've got two ears approximating a center image, so don't let it puzzle you if there's some fine tuning your ears will tell you to do. Sounds like you've caught on to the combing and smearing that occurs when you over adjust one direction or another.
> 
> 
> Sent from my iPhone using Tapatalk Pro


Ok. I've always done ta by ear. I'm not at all familiar with using a computer for alignment. I don't know the tolerances. I honestly was hoping this technique would be something that improved my sound as I'm always looking for anything at all to make it better, big or small.
Something interesting about this system that I've never had the pleasure of having with any if my previous system is I have no true nulls. There isn't anything that can't be eq'ed up with 3 or 4 db of eq.


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## ugnlol (Apr 14, 2010)

Pictures in first post are not showing up, possible to fix that forty5cal1911?


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## acidbass303 (Dec 3, 2010)

ugnlol said:


> Pictures in first post are not showing up, possible to fix that forty5cal1911?


+1

please fix the pic links


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## forty5cal1911 (Sep 11, 2006)

Sorry guys. I haven't been on in a while and didn't realize Photobucket had hosed me.

Sheesh.... they want $400 Annually to allow embedding. I'm going to move them to another hosting provider but can't edit my original post.

I'll post something up in the Site Support forum to request edit rights to my original post.


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## LayinLo (Apr 20, 2007)

Thanks @forty5cal1911 I actually have 2. A Dan Wesson Pointman Special II and a Gunworks custom from a Nighthawk Customs build.


Oh wait we are talking car audio. Thank you for the write up. Having spent the better part of the night reading this whole thread, and being somewhat familiar with REW from using the measurements in my home and speaker builds, I can't wait for sunrise to go give a first run in both vehicles. I'm hopefully optimistic to finally achieve some decent SQ even though both builds are more SPL oriented. I think the c-pillar wall having more of an up front presence has a nice tempting allure. There's no shortage of low end from (4) 15's. Now even more exciting will be the F-150 with it's 6th order bandpass. Can't wait to hear it ringed out.

So again, Thank You for taking the time to clearly outline the proper procedures and best practices. I've learned a lot from the posts here from Subter, drop1, babs, and other.

Best,

LL


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## LayinLo (Apr 20, 2007)

I'm still tuning my ears for some of this and learning what to listen for but this is how far I got on the Sexplorer. Just following the 1/3 RTA that someone previously mentioned. I made sure to get at least 75-80 averages per attempt. Usually it had stopped moving around the 40-50 mark.


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## jrwalte (Mar 27, 2008)

One question I had on this method.

I have a 3-way up front. Tweet, mid, woofer. It is mentioned OP used 1KHz for woofer and 2.5KHz for tweets.

So when timing the tweets, what is your reference? Do you run a reference on your right woofer at 2.5KHz to match up to? Or are you matching the 2.5KHz in the tweets to the 1KHz reference in your right woofer?


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## jrwalte (Mar 27, 2008)

Another question on interpreting the ETC graph.

I've set my TA based off using the impulse graph, following the guide with 1KHz and crossovers turned off for my mid and woofers. I used a 2.5KHz with ref to the Mid Right (I ran mid-right at 2.5Khz to establish reference) for the tweets. I aligned initial rise as best I could in the impulse graph.

However, my sound stage sounds far right and my original tape measure method has a better center stage.

I since saw in this thread to use the ETC graph instead. 

I've attached the ETC and Impulse for the measurements I took. On the ETC, should I be aligning all speakers to the initial peak rise or aligning the max peaks (at 100 in my graphs)?

Edit:
Looking at impulse for my mid/woofer, I can see my right woofer isn't delayed enough. I missed the initial rise at -2.5m, which I believe is my first peak I needed to line up.


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## DonGato (Feb 12, 2019)

Mlarson67 said:


> I used the exact method that was laid out. I used my right midbass as my reference at 1k. I then aligned the left midbass to it. I then aligned both midranges to it.
> There were some discrepancies with aligning them though. After measuring and adjusting according to the differences in the rise at IR. They didn't align perfect. I just kept tweaking the adjustments and remeasuring until they we spot on.
> 
> I then aligned both tweeters to the right midbass as well. Following the same procedure as before.
> ...


Sorry for being late, I am reading these post just now.

Please, explain to me these: 
If you use 1k for tweeters, you must keep the crossover on or you could blow them. If so, some people says that crossovers change the phase, specialy at crossover areas. If you bypass the crossovers 1k may damage the tweeters.

Am I right?

I am missing something. Should I do it with the same frequency for all the speakers or a different frequency for mids and tweeters. 

If I am measuring a 3 way system, what frequency do I use for mid lows? how do I blend them with mid highs?

Cheers!


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## tjk_bail (Feb 2, 2012)

DonGato said:


> Sorry for being late, I am reading these post just now.
> 
> Please, explain to me these:
> If you use 1k for tweeters, you must keep the crossover on or you could blow them. If so, some people says that crossovers change the phase, specialy at crossover areas. If you bypass the crossovers 1k may damage the tweeters.
> ...



I'm hoping you get an answer to your questions.... I am wondering the same thing....


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## subterFUSE (Sep 21, 2009)

You will not blow a tweeter by measuring it with a full range signal at moderate volume for a short period of time, unless it is a worthless POS tweeter.

Hell, I accidentally ran a set of tweets as midranges for 2 or 3 months before I noticed, and they are still fine.

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## DonGato (Feb 12, 2019)

subterFUSE said:


> You will not blow a tweeter by measuring it with a full range signal at moderate volume for a short period of time, unless it is a worthless POS tweeter.
> 
> Hell, I accidentally ran a set of tweets as midranges for 2 or 3 months before I noticed, and they are still fine.
> 
> Sent from my iPhone using Tapatalk




When I measured the tw with 1k and no crossovers, I heard an ugly clipping noise coming from them. I have a Morel tempo active set. 

What frequency do you recommend to measure mids and tw? 1k is easy to recognize but 3k is more erratic. 




Enviado desde mi iPhone utilizando Tapatalk


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## drop1 (Jul 26, 2015)

DonGato said:


> subterFUSE said:
> 
> 
> > You will not blow a tweeter by measuring it with a full range signal at moderate volume for a short period of time, unless it is a worthless POS tweeter.
> ...


Honestly I don't even bother using impulse on tweeters. You certainly can but if you follow a few simple steps you wont be able to hear the difference I promise you.

Eq your drivers, level matching them as you go. 
This will do more by itself for tweeters than any amount of time aligmnet. 
Once you are happy with your single side eqing and leveling, start delaying the divers side with only the tweeters playing some vocal. Because they are level matched at the drivers head, you can just put the center where you want it. Doing it that way is just as accurate as using a tape because they are the same volume at the drivers head. 
Next bring in the mids. Adjust both tweeters out the same amount. 5ms will be plenty. Then in small increments reduce the delay on both tweeters. The vocal will be the most transparent and clear. Thats the sweet spot and if done right the impulse would be super close to that. Weather using this string if sequences or using impulse, the outcome is always almost identical settings in the dsp.
This is my process.


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## DonGato (Feb 12, 2019)

drop1 said:


> Honestly I don't even bother using impulse on tweeters. You certainly can but if you follow a few simple steps you wont be able to hear the difference I promise you.
> 
> Eq your drivers, level matching them as you go.
> This will do more by itself for tweeters than any amount of time aligmnet.
> ...


I had some issues. I think I miss something. Here are my ir files where the pic is aligned but it sound weird.

Am I doing something wrong?


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## asnatlas (Apr 4, 2021)

Thanks @forty5cal1911


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