Is there a freeware alternative to APL TDA ?

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I've only just tried the APL software and like how easy it makes time aligning a multiway speaker. I've missed the offer to buy an individual licence for the cost of a student licence and as I'd only use it 3 or 4 times a year for setting up my own projects I'm hoping there is a freeware program that might do the same.

Thanks,
Rob.

edit - I currently use trueRTA for most things and have a full licensed version of acoustisoft ETF, if I can find my licence code off my old laptop :eek:

I use an ECM8000 mic with a behringer USB preamp for measurement.
 
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REW basically shows you the same information, but it's a bit more work to find it all as clear as APL_TDA does.

I really like APL_TDA and have almost promoted it's use around here due to that. As far as I know it's quite unique in the way it presents it's data. I didn't know Raimonds stopped giving us forum users the discount. Did you email him directly?

RePhase isn't a measurement suite. It's a versatile tool to edit phase/FR but can't measure and show what you want to see.
 
REW basically shows you the same information, but it's a bit more work to find it all as clear as APL_TDA does.

I really like APL_TDA and have almost promoted it's use around here due to that. As far as I know it's quite unique in the way it presents it's data. I didn't know Raimonds stopped giving us forum users the discount. Did you email him directly?

RePhase isn't a measurement suite. It's a versatile tool to edit phase/FR but can't measure and show what you want to see.

It was your posts that introduced me to the software, thanks!

I did get an offer but it was more than double the student price which, for the amount I'd use it, was too much for me to justify the spend.

I think with REW I'd need to dig out my old usb sound card to get it working right, I will have a look into it thanks.

Rob.
 
REW basically shows you the same information, but it's a bit more work to find it all as clear as APL_TDA does.
Took me a while to get around to it, but I have done a little work on that - mostly adding a linear amplitude scale option. Differences below 70 Hz or so but the speaker used for this test has little output below 80. I have also added the peak energy time as a trace on that graph so the delay time can be read directly from it.

APL.jpg

wavelet.png
 
I do have one request, if possible, could we see a little more data before the peak? In APL we can move the peak (to ~5 ms) to see the start of the wave shape, giving an indication of the energy before the peak. Might be useful to "see" exaggerated pré ringing from too much phase correction.
This graph runs to 30 ms, it would help to show an extra 25 ms before the main peak.

Like this DAC loop back:
dac.jpg


Compared to a Stereo measurement at the sweet spot:
stereo.jpg


I know this is the 3D view, but it would work as well in 2D to spot early arrivals (especially below 1 KHz).
 
I see, that's good to know. In APL_TDA I can move the graph by filling in a peak delay by filling in the time zero box (in ms). I assume in REW it is coupled to the start of the actual IR peak? I usually have the peak at t=0, never really tried to move the IR in time to see the pre peak data in a wavelet.
With a band pass phase like I have with my arrays part of the build up of the wave front falls outside the standard representation of the graph on the bottom end.
It shows as far as -8 ms of the pre peak, and if I adjust the limits to show (e.g. -25 ms) more of the pre peak area it just moves that graph up without filling in the missing parts (it does not regenerate the graph).
If I click the generate button again it just moves the graph back to the standard pre set -8 ms. I never tried to actually delay the IR peak (not having it on t=0), I figured I should be able to set wider time Limits to show me that pre peak part too. Am I interpreting this wrong?
 
The pre peak portion is 25% of the chosen range, so if you have a 30ms range there will be 7.5ms of data before the IR peak. With a 100ms range you get 25ms before the peak. The range that is processed is relative to the IR peak, so moving the peak will move the range correspondingly and you won't see more data. I could provide a separate control for the pre-peak portion, but it didn't seem a common use case to look very far into the 'past'.
 
If this new feature gets more use as a timing tool it might be of interest to see more of that side of the peak (as it will show the build up part of the wave, especially for the lower frequencies. I know I've been using APL_TDA for that personally, as a verification of what I get and see in REW.
I've always checked all my processing with REW as a tool, but did find APL_TDA a useful additional tool to verify. Now that you found a way to present a very similar graph, it just might provide a similar service as a visual (timing) tool.

So if it is possible, I for one would really welcome it. I had always figured that's what the Limits option would/should have provided, it just didn't work that way.

I can only make a deep bow for you, constantly evolving and providing such cool useful new features to an already very versatile measurement program. Thanks very much for the open way of communication too. I really appreciate it.
 
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