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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59231

  • entripy
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So my guess of 1.7ms based on your room size and likely placement wasn't too far off :)

Its hard to know whether that 0.1ms on the right speaker will make much difference but you have 4 SHD presets so its easy to experiment with accounting for it or not.

The numbers do seem credible. Sound travels at around 1 foot per millisecond in air (at sea level and 20C) so that 0.1ms does indeed correspond to a few cm. If you do take account of that 0.1ms it will effectively move the right speaker back a few cm acoustically which may actually undo your careful positioning, but I'm not certain of that.

Even before Dirac Live, the sub should already sound better integrated with that time-alignment.
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Last edit: by entripy.

Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59232

  • CarlosdelJunco
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thanks again entripy,

I'm going to forge ahead with Dirac Live at least to get some initial results.

Grrrr....yesterday I was able to load Dirac Live and it found the SHD. Today, it is not finding it. Tried re-booting laptop and didn't fix it.

Scrap that - just got Dirac Live to find SHD after making a few adjustments.

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Last edit: by CarlosdelJunco.

Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59258

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Hi @carlosdelJunco

Did you get the Dirac to work? Was all this alignment make that much of a difference?
 
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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59259

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Thanks TVM for your question,

I did get it to work but I think I must have not left pre Dirac Live measurements with REW - to integrate time alignment of subs to my 2 main speakers - properly. In a nutshell I scrapped the results and will try again either today or tomorrow when I have the time.

I'm going to to start a new topic called "Proper REW measurements w sub settings before doing DiracL sweeps?".

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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59262

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I will surly follow. The wisdom I have seen so far (forums and youtube) indicates that the right way is to do the time alignment and sub PEQ before Dirac (and other RC suits). Would be interesting to here your results. I don't have Dirac and wonder how beneficiary it is.
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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59263

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I just posted the new topic with LOTS of interesting observations and questions comparing DiracLive vs REW as a standalone (maybe REW is the better platform than DiracLive) to do one's DSP room correction along with minidsp products.

That said, there's a bigger learning cure to using REW. But I'm getting more comfortable as I dive in and read both REW and DiracLive manuals and watch videos. Anyway, my new post is called: 

"DiracLive vs REW Auto EQ for optimal DSP room correction with miniDSP?"


 

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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59302

  • CarlosdelJunco
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Hi entripy and TMV,

Ok, I got better results today...still feels like it almost cuts too much high end and so now playing manually with the slope in Dirac Live. 

Weird thing is I re-did my time alignment for subs and mains before doing the DL measurements today and got quite a different reading only moving my mic position 3 inches to the left - so that the mic was exactly equal distance between the two satellites. The last time alignment reading for sub and mains was about 1.65 ms, and today's reading was 5.7 ms. That seems bizarre to me as it's quite a difference to the first time alignment test I did.

I also had to turn my sub way down (about -6dB) after loading saved Dirac Live preset from today's DL measurements.

I'm considering getting a second sub for true stereo and to help with low end room modes. Again, entripy, thanks for your help and clarifications.

 

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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59303

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If you have got used to listening to poor room sound, Dirac Live corrected sound can seem awful on first hearing. You often need to listen to it for several days for your ears to unlearn the rubbish they got used to. After you have got used to it, disabling it can horrify you.

It is also common to not get satisfactory results on your first N attempts. For me N>4.

A bit worrying that your time delay was so different though. It would be good to get that more repeatable to trust it. An optimal integration depends so much on that.
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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59305

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Ok...I have at lest 2 more DL measurements before catching up with your N>4 entripy!  ;-)

That said, I see what you mean as my ears adjust to the newer sounds. Stepping away and coming back allows one to be more objective as well. 

I'll also retest time alignment. Would changing the Crossover affect time delay..? I'm guessing not.

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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 1 week ago #59306

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Changing crossover shouldn't have a significant effect on time delay, no.
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Time alignment method for sub integration for stereo speakers with SHD and REW? 9 months 2 days ago #59587

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Hi entripy , altsouza or Ultrasonic ,

Well, I got a second sub to run in stereo and got them positioned them the only way they are going to fit in the room, directly behind each main stereo speaker and more or less each tucked in the back corner of the wall behind the main speakers.

So, before doing any time alignment measurement between the two mains and subs, I used a method on a Youtube video (you can find that video on page 1 of these posts) using the "alignment tool" in REW recommended by altsouza (thank you!) to first "sum align" the two subs and figured out there was about a 4.08 second delay where I got good positive summation graphically of the 2 subs as directed in the video...however i'm not sure what I'm supposed to do with that 4.08 ms delay between the first and second sub when it comes to figuring out the timing delay between L & R speaker and the "summed sub".

I then did the regular measurements in REW to time align the L & R speakers with the "summed subs" and figured out there was a 2.71ms delay and entered that into miniDSP SHD for the L and R satellite channels. So far, so good.

So, is this all I need to do before doing my Dirac Live measurements, or do I need to consider this 4.08ms delay between the 2 subs and enter that somewhere in the SHD settings?

After establishing entering my crossovers in miniDSP, I did start trying to do Dirac Live measurements and no matter what I did kept getting warnings there was too much background noise - when everything was indeed quiet, ie, furnace fan and fridge is off.

However, one thing odd I noticed and  quite sure is different from the last time I did my first two sets of Dirac Live measurements over a week ago is that setting the mic level and speaker volume in Dirac Live - I was only able to register the level for the left speaker. See the attached screenshot that shows me playing the test pink noise but the right speaker (which is sounding equally as loud as when doing the left speaker pink noise test) but does not register any volume as it did for the left speaker. I don't think it was like this when I did my first two DL measurements.

So, after quitting, rebooting my computer and restarting the SHD plugin and starting up Dirac Live again from within SHD, I also got this warning (see screen snapshot) "Cannot Check Master Gain"...not sure what is going on as everything seemed to work fine a week ago when doing my first couple measurements.

Any insights or suggestions double be greatly appreciated.  :-)

 
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Last edit: by CarlosdelJunco.

Time alignment method for sub integration for stereo speakers with SHD and REW? 8 months 3 weeks ago #59664

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Hi Carlos,
1. You have to apply the 4.08 ms delay to the Sub, in SHD plug in
2. After that , you re-measure both subs together
3. Then you align L+R to the SUB1+Sub2

It is better to apply mono signals to both subs. You do that in the SHD Plugin's output matrix!!!!! You check both boxes in both subs
 
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Time alignment method for sub integration for stereo speakers with SHD and REW? 8 months 3 weeks ago #59665

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hi altsouza,

thanks for your reply - and encouragement to get a second sub!  :-)

I think I got my first half decent results today following basic instructions from minidsp article "Subwoofer Integration with the miniDSP SHD and REW" article - and using STEREO subs!  

Anyway, with an Auto EQ to help flatten the sub, it quite well, and adding a custom PEQ in about 3 different frequencies between 75 to 200Hz for the mains, I'm in "reasonable" shape. I say that as I've had to apply quite a steep Q and BOOST at about 130 and 200Hz (which I know is not ideal to apply between 7 and 9dB boost) where there are big dips in my space.

I know you said to sum the subs to mono. I think I can hear the difference, or perhaps "feel" the pressure difference when in stereo as opposed to mono. I used 80HzBW 12dB/oct crossover. Once I time aligned the subs (again 4.08 delay on Right sub, so applied that to Left channel sub on SHD), I then tried a few different Auto Eq configurations on the 2 subs together and once I found something decent, I also played with a few different crossovers and doing more measurements before deciding. I'm liking the 80Hz crossover over best as the sealed cabinet subs add a certain tight punchiness when going that high a crossover that I find the ported Harbeth C7 speakers lack (even though they go down to 45 /- 3dB). Then establishing a baseline time delay between main and subs, did a bunch of further measurements changing main speaker delay in increments of .5 seconds to see what gave the best response in REW.

I'm still dealing (I think) with something buggy going on in Dirac Live and presently unable to take measurements with DL. I'd sent in a support ticket, got one answer earlier this week and waiting to hear back after I sent them some screenshots and even a short laptop screen video showing them exactly what's going on with the Dirac Volume Calibration page where Dirac doesn't acknowledge my right speaker even though there's healthy 75 to 80dB of pink noise coming out of it. Can't figure out if it's me or just buggy software. Strange thing is this only started after hooking up the second subs. Everything is routed properly since REW works and recognizes correct Left/Right/Left Sub/Right Sub channels in tandem with SHD software.

Photos of my "Crazy Covid Kitchen Project" where I built a few sound panels this past summer, some 6 inches deep (2 feet x 4 feet) with two different densities of Rockwool, denser at the back of the panels, and 3.5 inch holes drilled up and down the sides and bottoms of the panel sides. Those rolls on the floor are 1 inch thick matted wool fibre padding tightly rolled, also 1 inch thick padding under the rug wall to wall. 3.5 inch deep panels on ceiling. All this made a HUGE difference...we are talking about a kitchen after all (with a fridge and stove starting 5 foot narrow floor space between counters going down the length of the 9 x 17 room), so it's a major uphill battle to get things sounding more even. While I know these panels and tight rolls are not dealing with sub frequencies and other mids, it's helped immensely overall with creating a fantastic dead end wide sound stage where the speakers live, so where I hang out cooking in the middle of the kitchen, things are sounding pretty decent. I know it could sound better and can't wait to get Dirac Live working again. You have to "scroll" these photos to get the full picture...
 

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