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First thing I'd do is forget everything else and just do individual plots on your mids and make those corrections to get their individual plots looking more identical in REW. Then go at TDA again with their timing in mind and an idea of their distance differences.
Yeah, I am starting back at square one. I am going to focus on making sure I have everything dialed in with REW before trying to utilize TDA again.

I'll probably post over in the REW dump thread once I get to work on it. Try to get some opinions and make sure everything is copacetic before proceeding further. I may be going to the big SQ show at College Station in June, so I have to get a good tune in, lest I be embarrassed to demo my truck.

And my new Cross Spectrum UMIK just arrived, time to get to tuning!
 

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I'll have to check a full system rta when I get a chance. Usually, I can get 1.5k-20k for both channels to overlap with very nice accuracy. But after I go through and balance for center imaging stuff doesn't look so nice anymore. I'm curious how they're combining overall. I hate not having a peq for the mids though.
 

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A new version of TDA no.11 came out from the Raimonds's table. Now it can also show phase graphs.
 

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If one has a capacity limit in TA, what is the best solution? MiniDSP? Others?

I am looking for DSP or simply cheap time machine with more than 20ms.

Has anybody tried to ask Raimonds about limitation in the APL1 soft (less than 5ms)? Is it possible to increase this figure or not? Are there any soft upgrade for the APL with better TA possibilities?
 

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Discussion Starter #126
If one has a capacity limit in TA, what is the best solution? MiniDSP? Others?

I am looking for DSP or simply cheap time machine with more than 20ms.

Has anybody tried to ask Raimonds about limitation in the APL1 soft (less than 5ms)? Is it possible to increase this figure or not? Are there any soft upgrade for the APL with better TA possibilities?

MiniDSP 2x4 with rear center plugin can do 27ms. It has other limitations though. DCX2496 can do like 1000ms lol.

The 5ms is an offset of the IR wave, should be possible to offset more... I'll send him a mail later.


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If one has a capacity limit in TA, what is the best solution? MiniDSP? Others?

I am looking for DSP or simply cheap time machine with more than 20ms.

Has anybody tried to ask Raimonds about limitation in the APL1 soft (less than 5ms)? Is it possible to increase this figure or not? Are there any soft upgrade for the APL with better TA possibilities?
One option to get more delay is to route the output of a DSP channel into an input and then route that input to another output. You could then use the delay on both DSP channels to cascade up to 30 ms on a Helix DSP Pro.

Only downside is this must be done analog.
 

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Yeah, I am starting back at square one. I am going to focus on making sure I have everything dialed in with REW before trying to utilize TDA again.

I'll probably post over in the REW dump thread once I get to work on it. Try to get some opinions and make sure everything is copacetic before proceeding further. I may be going to the big SQ show at College Station in June, so I have to get a good tune in, lest I be embarrassed to demo my truck.

And my new Cross Spectrum UMIK just arrived, time to get to tuning!
Your gonna have fun with the UMIK-1. I suggest trying the method I sent you in the youtube vids for quick measurements in RTA, comparing sides, setting levels and knocking down peaks to get the drivers looking like each other. I know folks are advocates for sweeps for accuracy, so to each his own. RTA averaging in REW is quick and ugly and kinda gets it down at about 1/12 smoothing.

One way I've done it is to measure one side (side 1), go after the nasties with EQ to get a good looking response, save the plot, go to the other side 2, repeat, save, and compare to side 1. I might go back/forth between them a couple times with end goal in mind of a good plot and matching plots. I find if I distance myself from trying to reach any "curve" at this point it works better.. By working on curve stuff afterwards when multiple drivers are playing (sides, pairs, groups), AFTER TA and centering of course.

Looking good. I would be curious to see how your sub delay would change by using a 2nd order butterworth.
Interesting result here.. I switched to butterworth and had to back off on delay then flip the sub 180 to phase in. Without researching the difference in butterworth vs LR filters, I assume it's the nature of difference between them, but it dialed in nicely.

All said, I have to refrain from having more tuning fun and force myself to tear it down.. Pillars for the 3-way and an IB wall to do. :D So I can really boogie in the door mids when they no longer have to pull midrange duty above 400ish.
 

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One option to get more delay is to route the output of a DSP channel into an input and then route that input to another output. You could then use the delay on both DSP channels to cascade up to 30 ms on a Helix DSP Pro.

Only downside is this must be done analog.
If one has a capacity limit in TA, what is the best solution? MiniDSP? Others?

I am looking for DSP or simply cheap time machine with more than 20ms.

Has anybody tried to ask Raimonds about limitation in the APL1 soft (less than 5ms)? Is it possible to increase this figure or not? Are there any soft upgrade for the APL with better TA possibilities?
Is the APL1 JUST EQ, or does it also do TA and/or phase? It's kinda vague from memory looking at them.
 

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APL solves minimum phase problems and by this optimizes the time alignment. To a certain degree of cause, as there are many other problems in a car cabin. This will be done automatically by EQ the system. Subwoofer delay partially can also be closer to the front (max 5ms), but this has to be done manually while uploading FIR filters to the unit.
 

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Any help interpreting the results?

Full system.

Sub: 20Hz/6 - 80Hz/24
Midbass: 63Hz/24 - 250Hz/24
Midrange: 250Hz/24-6000Hz/24
Tweets: 6000Hz/24

All drivers have been individually EQd using REW to a target response. No TA set.

 

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Question. Using TDA will dial in both drivers to the business end point of a measuring mic. Brilliant thing. However, should you want to steer center a tad more left than the acoustic center between drivers which is rather right-sided in my car, is it safe to assume that'll completely screw up your TDA plot? So in that case, TDA will help you find dead center timing, then you're on your own if you're tuning to a more frontal center for stage depth perception.


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If you don't want it right, you're on your own ;)


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Well actually properly timed its kind of "right" meaning center is perceived as intersecting between midpoint between drivers, geometrically speaking. If that makes sense. So there's a fine line of staying with that and some point left of that so not too far left to compress left stage and stretch right stage. A matter of a couple inches if looking at the rather long dash.
 

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That does broach the question of rather "tricking" the results with mic placement. Hmm. According to tracerite, to steer to the left, you subtract delay on left, add delay on right, this bringing the theoretical left driver closer, right driver further away. So, if you positioned the mic for TDA slightly more to the left, this might simulate the same result, no?

Might be worth some fun for center steering experiment. I guess we're taking splitting hairs here. But hypothesis being that when your noggin is listening in same 0-point position after -2" TDA mic position (left), the result would be a slightly more left center image at your ears, still well timed. So, If you move your head an inch or so left, so ears center where the mic was at TDA measurement, it'd be exactly timed and ITD stage (dunno if that's proper term but I'll go with it) should then move rightward. ??

Not counting leveling adjustments of course, since image is ITD and ILD driven (and I'm only beginning to understand those so I know I'm no expert nor claim to be one or even play one on TV). :)


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Hey scott, one thing to keep in mind about nailing t/a, are the advantages to stage reproduction as far as depth, perceived ambience and such. Not only are you working for a proper center, you're building the stage and the phase adjustments make sure all the geometry is kept in order when listening. I mean, I can center my stage with t/a....... and levels. You can have yer levels just right, and center well, but the overall stage representation can be funky from t/a errors.......on the other hand, you can have your t/a dialed and still skew yer stage with levels and eq. To add to the top of this complicated stage construction, you can have your t/a and levels dialed, then funk up the phase with eq, requiring t/a adjustment, which can in turn funk up your tonality.......lmao, this whole hobby can be maddening, but it is a serious challenge, and no car is perfect, they just have different disadvantages. The key is making the right compromises to satisfy your ears........
 

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Discussion Starter #138
Moving the mic to the left would simulate more required delay to left side. More delay on left channel moves stage to the right. I think you need to place mic to the right. Then there would be less delay on left channel and stage would move to the left.

Hate thinking backwards, I might got it wrong...


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Set T/A using distance to drivers first off otherwise it will look like that. When you have done that then we can start to interpret it...


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As requested.

Times set using the trace rite website. I set the midbass/sub delay using the 'cross over' method?

Values:
RTW: 1.77ms
LTW: 0.53ms
RMR: 1.55ms
LMR: 0.39ms
RMB: 6.51ms
LMB: 4.41ms
Sub: 10.02ms 180deg phase shift

 

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The idea of null-delay in the low end has resulted into new set of measurements and XO/TA settings.

Initial info: sedan, 3way passive, sub almost without EQ possibilites (only from HU), APL1 - only for the front channels.

After some attempts I came to the following results - see attached graphs. Tests were made both in TDA and REW in the same single point at the driver's headrest (no averaging). Therefore - information above 1 kHz is not so interested here. My intention was to minimize delay of the sub when connected to the front by different sets of XO and TA settings. The best was achieved by implementing the TA difference between the left and right channel of 51cm, while actual difference from the listening position is only 27cm??? When applying the settings close to 27cm, the closest channel is dominating, moving the scene to the left. Remind, I do not have possibilities to adjust the volume for a separate speaker.

All these three pictures show 2 channels +sub playing simultaniously.

DFR shows less than 1 ms above 500Hz and around 2ms from 40Hz!!! until 500Hz. I suppose that below this we can see nonlinear things based on the mechanical construction of the subwoofer speaker and its work in a sealed box. Correct me if I am wrong on this statement.

What is interesting, that the REW mesurements showed a significant GD (appr. 60ms), while dfr (TDA) has not revealed this. On the other hand, we can observe some energy (delayed in time domain for the same value) on the 2D graph.

Impressions - as there is no many sounds below 40Hz in music, compared to other frequencies, this might be expected some audible improvement of the sound at the LF. And that is correct: sound is more tight, clear and straight forward.

Present XO points (due to the lack of TA capacity - used everything possible in HU/H100 -336cm): 50Hz, 6dB/oct - sub, 63Hz, 12dB/oct - mid.

Comments are very appreciated.
dfr.jpg 2d.jpg GD REW.jpg
 
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