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TDA (Time-domain analysis) - Measurement Software - Review

32K views 209 replies 29 participants last post by  Durgesh 
#1 ·
Here's another review which is a continuation of the APL unit I reviewed some time ago (which was planned before my little ragequit on DIYMA)
. All right, here goes:

Link here: APL-Review.

Here's a link to the official homepage: TDA - Time-Domain Analysis

TDA is a measurement software with the ability to measure how time coherent your system is with a touch of a button. Incredibly easy in other words. It can also view the IR, harmonic distortion 2nd-10th order, AFR (magnitude response). This is a great tool to evaluate phase/time coherency, to troubleshoot and optimize your system.

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The system in the example below:

*2-way + sub (10" sealed, Qtc 1.2, Fsc 58Hz)
*APL1 + MiniDSP 2x4 and subwoofer controlled directly from an Alpine CDE-175R

*Crossover points:

Mids, 120Hz LR12 HPF -- 3200Hz LR24 LPF
Tweeters, 3200Hz LR24 HPF
Sub, 100Hz LR24 LPF


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1. Full system (L+R) - No EQ - No T/A (Initial crossovers set and optimized)








2D/3D/DFR View. This is basically a mess. No coherency at all and as expected no stage at all. If we take a look at the averaged measured response you can see that the peak around 500Hz correlates with the offset in delay (group delay spike).



2. This is after I've setup T/A by ear and setup EQ for both channels (see the picture above). There's still a jump in relative delay below 200Hz and this is due to the subwoofer blending with the front stage (crossed fairly high). The system sound good/balanced and center staging is great now.

EQed response and "by-ear T/A"


To verify if the APL unit did proper corrections I saved my settings and returned the system to its initial setup with no EQ applied and let the APL software do its thing. The result below:

APL corrections with the initial settings as base


As it can be seen the delay between 60-200Hz has been greatly improved and it does the job overall very good if you compare it to my tedious tuning session. Male vocals, harmonics of drums etc now stages better with increased perceived depth in stage. The jump in delay around 50-60Hz is the inherited group delay of the sub, it got some peaking due to a fairly high Qts of ~1,2. (In LEAP (modeling software) it displayed a 9ms GD peak @ 55Hz in an anechoic space.) I later improved additionally on this but forgot to save the IR...

Here's the DFR (Delay FR) of the system. This is the same thing viewed as a normal graph if you prefer such a view.



I assume the little peak at 3,2-3,4kHz is actually the crossover between mids/tweeters. The group delay of a Linkwitz-Riley 4th order filter is 0,5ms in theory so it could be viable.

After setup I confirmed the coherency once again by doing a noise / RTA average in the listening space. See the picture below:

Correlated vs Un-correlated noise and A/B difference.


This is the full system playing. Uncorrelated noise is noise recorded in mono, since most vocals and lot of other content often is mono, this represent to a large degree how the mono-FR looks. Correlated noise is affected by incorrect settings in the time domain and large dips show up which are multiples of each other at different frequencies in the magnitude response. Uncorrelated noise is a random generated noise distributed in both channels, so uncorrelated is basically stereo. This isn't affected by standing waves/incorrect T/A settings in the same manner and most often looks far better in an initial setup. By directly comparing them, you can make a rough estimate how much interference there is in the time domain (destructive interference).

For a final test I used my best setting and offset T/A by 1ms, results below:

T/A offset by 1ms


T/A offset by 1ms - Amplitude difference (full system active)


Again a mess... this is with a perfect L/R FR. T/A is very important to get right as you all probably know.

If you want a software solution that does T/A analysis for you in an easy and efficient manner this is indeed a great program!

There are several other applications for this software too, troubleshooting incorrect polarity/phase, speaker optimization etc.
 
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#3 ·
Quick question.....does the apl unit work with this program and perform corrections, or is this software independent and just a way to visually display delay? Also, can this software be used to display left right delay, or just the image of your whole system to phase align the mids, highs, lows, and sub? Sorry, more than just a quick question, but the apl unit grabbed my attention early, with price being the only thing holding me back. Does this software apply to the apl, or is it just another offering from the same company?
 
#5 ·
I had left and right tweeters on at the same time. Then left and right mids. Don't bother T/A the drivers to each other on each side. If I'm doing it by ear I simply pull down the highpass on tweeters to the 2kHz range, then turn everything else off. Then adjust T/A until it stages in the center. Repeat for mids till they stage at the same point. Works for me every time and it sounds coherent, the measurements also confirm it. Even though in theory it shouldn't be audible due to the range most tweeters are reproducing (well into the IID-range), it is - at least if the crossover is near or at ~3kHz.

The only problem is that it can be deceiving doing it by ear because you get very easily fooled by any level difference in the higher frequencies. EQ must be precise for my method to work properly. TDA does it without having to bother with this as it only takes the delay into account, it makes the tuning process much faster and less tedious as any proper measurement do.
 
#7 ·
To be honest I've not looked into doing such measurements as these much until now. There are methods to adjust delay by lining up the IR to eachother for example but that won't give you a complete picture of what's going on in the entire range. I'm unsure it's possible to view the relative delay with any widely available software in this manner. Individual channels can be displayed by looking at excess group delay, I do not know how combined channels measurements would look or to be interpreted as of now. TDA is great because it's so straightforward to perform the measurements and leaves little room for misinterpretation.

Sent from my Samsung Galaxy S5 using Tapatalk
 
#11 ·
I think the TDA would be more similar to stuff found in the pro world like SMAART and Systune. But those don't have the ability to export files to the APL1 to do phase correction (which I think it does).

The TDA software is a pretty unique way of visualizing delay, phasing, and even speaker resonances.

If I win the lottery, I would like to have a few APL1s.
 
#15 ·
well, no matter, I'm not paying even $75 for a software plus hardware commitment that doesn't tie my shoelaces...


:D

I am pretty happy with the sound the MS-2 makes, overall... heck. I probably don't even need DSP at all, I know I enjoyed my stereo over the past 30 years, with the majority of those years going no more involved than adjusting treble and bass shelving, haha...

still, a consumer dropping $835 on software just to make pretty graphics is what I'd call hard core.
 
#16 · (Edited)
Hanatsu, et al -

A lot of this is over my head, so please be patient with my questions.

I read through the APL website and even tried looking at the patent. For me, the best overall explanation of what TDA, and APL are doing is here -> Acoustic Power Lab :: SPFR

The various descriptions make it sound as if multiple measure points are being used but from what I read above, Hanatsu implies the mic is placed on the head rest and the SW does the rest.

Please clarify this. Is the measurement mic moved around when using the all-in-one APL correction box, or is it kept in one place? If it is kept in one place, then is the SW using time-gates and FIR to create a *virtual* multi-point measurement set?

Again, sorry if above is using technically incorrect terminology, I'm just trying to wrap my head around what this stuff is doing and why it is different.

*** EDIT: I see upon more careful review that I got confused between TDA and APL. Most of my questions were answered in Hanatsu's APL Review thread. ***
 
#17 · (Edited)
Sorry. I have some additional questions:

It seems that the APL1 device would be capable of (nearly) perfectly time-aligning a system, even if it is using passive crossovers. i.e. by using an FIR based complex power spectrum (phase & amplitude) measurement and correction, each frequency will be time-aligned by the processor, and the need to time-align individual drivers is minimized (or eliminated, or improved upon)?

Another question: In addition to aligning the primary path to the listener, it sounds like APL will correct for the major reflected paths. Is this true? If so, does it do this by cancelling those paths, or by aligning them at the listening point to sum with the main path?

*** EDIT: I see upon more careful review that I got confused between TDA and APL. Most of my questions were answered in Hanatsu's APL Review thread. ***
 
#20 ·
The way APL measures and corrects for response irregularities makes it consider reflections in another way than just doing it "the usual way". What is does is basically to take samples of the power response at multiple spots that "creates" the sum at the listening position rather than measuring the sum itself. It does this by an impulse response, not by noise which cannot register any phase/delay information. It does fix most minimum phase regions. Non-minimum phase regions are modal dips for example (which can't be fixed by any type of processing). The minimum phase corrections increases coherency in staging since left and right side is corrected for indiviually, I believe this is the main cause for the increase in perceived depth and focus in the lower midrange.
 
#21 ·
New TDA version is available now.

APL TDA EQ measurement and equalizer synthesis software:

Uses Time Domain Analysis for an equalizer creation. The detailed equalization of TDA EQ is suitable for any critical loudspeaker applications, in particularl, studio monitors. Output *.fir files go to APL1 unit or APL EP1 VST plugin.
 
#23 ·
No, I have not. But idea to send EQ file directly to APL (including TA) is very attractive.

I would agree with Raimonds that the Workshop is more accurate and more powerfull for EQ task in a car, as you are not bend to the listening position as it is the case of TDA.

My experience is that it is rather difficult to achieve the same repeatibility with TDA compared to Workshop. If you use both - then you have all the necessary info to tune the car in the best way :)
 
#24 · (Edited)
It was fun to see how just 1ms can destroy the sound image. I made also some funny things, trying first to delayboth front channels against each other with 360cm (max possible in the present HU) and to see how they will play:

http://i430.photobucket.com/albums/qq28/Alexander_Souproun/Right 0cm_3D_zpsalw9jdpb.jpg?t=1451936064

Then by reducing the mutual delay I moved to the "image position" of the optimum. In my case (3way passive + sub in the trunk) this was achieved at 28cm (again - we are talking about very rugh adjustment, which accuracy is limited by HU).
 
#26 ·
Some more pictures from the last tests with TDA:

Pic1. Mutual cancelling of the front channels (appr. 260, 460, 800, 1600Hz) and influence of the infrasonic filter.

Pic.2 - Best possible dfr for the present install (3way passive)

Pic.3 - 2D delay presentation



As one can see, cancellations on the first pic. are gone. Without infrasonic filter the sub became "closer" to the front. Sounds more tight and accurate.

Blue Rectangle Colorfulness Electric blue Display device

Text Line Pattern Square

Screen Colorfulness Display device Technology Multimedia
 
#27 ·
Ok gentlemen, I need help in figuring out what I'm doing wrong. I went to the apl/tda website, and decided I'd try the tda trial software.....so I was informed I needed to download some software, don't remember the name......version 2013 8.1mat play or sumthin.... and I followed the link and did that....then I downloaded the trial version of tda. The only evidence I see of tda on my computer is the installer program....I've installed a number of times yet still no tda on my computer that I can find.....ugh. Can someone please walk me through exactly what they've done to make this work on their computer? I hope so, I've read the directions on the tda site, and I'm obviously missing something. Please someone help this barely computer literate feller out!
 
#36 ·
Mine was doing the same thing, you need to extract the files from the zip, then just click on the little TDA icon like normal.
 
#28 ·
In order to use TDA you need to download and install Mathworks Matlab compiler runtime (MCR) 2013a 8.1 according to your operating system type, Windows 32 or 64bit!

Please check what version of windows you have on your PC - 32 or 64. I have never had issues during installation of this program on XP.
 
#29 ·
Ok....I did that windows 7 64 bit......I did this before I even downloaded the tda software. Anything I could be missing?

I did get a message saying the tda may not have installed correctly....mtry again with recommended settings....but still no good......ugh.
 
#32 ·
I usually have to run as Admin to get mine to work so definitely worth the try
 
#35 ·
My goal with my new build is to produce a TDA plot that shows 0ms delay at all frequencies :p

Might sound impossible but I'd like to try, with properly implemented FIR processing, the low frequency group delay can be removed to a large degree...
 
#40 ·
I did, but at first I had the wrong version of matlab.....so I uninstalled the wrong version, as well as the start up file for tda......got the right matlab, then went back and got tda again. I didn't get the chance to meet with it yesterday, so maybe this evening I will drag the laptop back out and try again...........thanks guys for all the suggestions, I may be back tonight if it doesent pan out......lol. I didn't specifically make any choices about admin.....is this something I need to go to another menu to choose as an option?
 
#41 ·
Yes, there is a specific option for opening it as admin. Right click on the TDA icon that opens the program and you will get a menu of options. You will see an option to open/run it as Admin.
I had to extract the files from zip and run it as admin. When I only extracted, the program would open but not let me measure.


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