Can anyone help with Alignment?

[3ll3d00d]

I was posting about the sub build in DIY Audio and someone kindly modelled the sub for me:

Seems a reasonable approach if that's the extension/output you need

 

[Robbie010]

Thanks Guys.

So, I've measure the subwoofer near-field (1cm), flattened the response with a shelf and added a PEQ to boost the low end. Looking at the curves, a standard 80-90hz crossover seems to be in order.

The subwoofer is positioned off to the right corner:

According to the subzone app, positioning the subwoofer anywhere between the speakers is one of the worst places in my room with the best place being around 3 feet from the corner along the right-hand wall, which I may be able to get close to:

With regards to the alignment, should I be trying to align the subwoofer with one speaker, both or some kind of middle average?

 

[dualazmak]

With regards to the alignment, should I be trying to align the subwoofer with one speaker, both or some kind of middle average?

I, at least myself, believe that you would please carefully try "the three" time-alignments you suggested, and select the best one through your careful subjective listening evaluation/preference using "proper and suitable" music tracks having nice bass sound in sub-woofer Fq zone.
Edit:
Or, it would be highly possible that you would find little timing difference between the three measurements since you have only one subwoofer near to the SPs and all of them are located rather far away from your listening position.

Just for your reference, you can hear these on YouTube:
- Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

- A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #63(remote thread)

If you would need some more music tracks from various genres to be heard on YouTube, please visit my independent thread;
- An Attempt Sharing Reference Quality Music Playlist: at least a portion and/or whole track being analyzed by 3D color spectrum of Adobe Audition


Furthermore, only if you would like to measure/check/confirm your best-felt time-alignment visually objectively, I would like to suggest you applying the single-sine-wave matching method,
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507
but I think you have no need to go into such a "deep and precise" objective measurement since you have only one sub-woofer now at rather long distance from your listening position. I mean that your subjective assessment for optimization/selection among the three measurement values will be just enough at this moment.

 

[Keith_W]

With regards to the alignment, should I be trying to align the subwoofer with one speaker, both or some kind of middle average?

You will be aligning your subwoofer to the summed response of the left and right speaker - i.e. both speakers swept together.

 

[dualazmak]

My personal guess/prediction would be that you will find your optimal group-delay of your main SPs against the subwoofer somewhere between 12 msec - 25 msec in your present system setup.

 

[3ll3d00d]

I've measure the subwoofer near-field (1cm), flattened the response with a shelf and added a PEQ to boost the low end.

You may have done this already but unless you listen at v low levels, you really need to model the effect of that on excursion.

 

[dualazmak]

Please be reminded that in anechoic ideal acoustic environment, 10 msec group delay of main SPs against subwoofer corresponds to physically pushing/moving the subwoofer 3.43 m forward towards your listening position since sound velocity is 343 m/sec at room temperature of 20 degree C.

 

[Robbie010]

Delays are very confusing.......

After playing around for a few hours I have ended up here:

This is both speakers and the subwoofer driven with the mic at the listening position.

I have given up on the Visaton tweeters and ordered a pair of Fostex FT7RP Ribbon Tweeters, so hopefully they will get me closer to a flat response above 10khz.

More to follow.

Thanks all.

 

[levimax]

That looks OK, usually the ASR "standard" is to have the left scale with a 50 dB range and 1 db increments, your scaling makes it look "better" than it is.

Regarding timing and testing your integration I understand how hard and confusing it can be. I would try several of the methods given and see if they "agree" and if not why.

For "sub integration listening tests" I like to use the "Neuman's Kick Drum Train" file which is attached. You can play with the delays and hear differences... a good "kick drum" sound is a good test for subs and their integration. It might also show other issues like "bottoming out drivers" and "clipping" caused by DSP which if you see something unexpected you would want to investigate.

 

[Robbie010]

That looks OK, usually the ASR "standard" is to have the left scale with a 50 dB range and 1 db increments, your scaling makes it look "better" than it is.

Regarding timing and testing your integration I understand how hard and confusing it can be. I would try several of the methods given and see if they "agree" and if not why.

For "sub integration listening tests" I like to use the "Neuman's Kick Drum Train" file which is attached. You can play with the delays and hear differences... a good "kick drum" sound is a good test for subs and their integration. It might also show other issues like "bottoming out drivers" and "clipping" caused by DSP which if you see something unexpected you would want to investigate.

Thanks for the file.

Like this?

 

[levimax]

Thanks for the file.

Like this?

View attachment 484869

Scale looks correct. How does it sound to you?

 

[Robbie010]

Scale looks correct. How does it sound to you?

It sound very good, the bass isn’t too much, definitely not boomy or overblown.

However, I keep thinking I can sense the bass from the direction of the subwoofer but I’m not sure if thats just my bias. Maybe the delays are not right and I’m getting the low bass from the sub before the main speaker bass.

 

[levimax]

However, I keep thinking I can sense the bass from the direction of the subwoofer but I’m not sure if thats just my bias. Maybe the delays are not right and I’m getting the low bass from the sub before the main speaker bass.

There is a thread on subwoofer localization. https://www.audiosciencereview.com/forum/index.php?threads/locating-bass-80hz.66617/ Bass location is apparently FAR from settled science which leads to some "interesting" comments

What crossover frequency/ slope are you using?

 

[Robbie010]

There is a thread on subwoofer localization. https://www.audiosciencereview.com/forum/index.php?threads/locating-bass-80hz.66617/ Bass location is apparently FAR from settled science which leads to some "interesting" comments

What crossover frequency/ slope are you using?

Thanks.

Crossover is 80hz, L-R 12db

 

[Robbie010]

Not sure whether it makes a difference but the subwoofer is playing right to left across the width of the room, speaker playing along the length of the room.

 

[levimax]

Thanks.

Crossover is 80hz, L-R 12db

It would not surprize me that you can locate the sub... it's not the 80 Hz but at only 12 dB per Octave you are only down 12 dB at 160 Hz and anything over 120 Hz is usually pretty easy to locate. Why did you chose 12 dB per Octave? You probably will need to "reverse polarity" of the sub to get it in phase. I would try 24 dB and 48 dB and see what happens, at least they are "phase coherent". You should actually be looking at "Acoustic" slopes not electrical ones and I don't know what the roll off of the sub and mains looks like at 80 Hz but you may need to take that into account when setting up your sub crossover.

While others have been successful setting up one sub "away from" and "at different distances" from the 2 mains speakers I have never had much luck doing it that way. Even though the FR may not be as smooth I have always ended up preferring "co-located" subs and mains if using 2 subs or "close to and equal distance from both mains" if using one sub. At the very least it makes it much easier to think about how to set the delays . It also allows a lot more flexibility for the crossover point. In many cases a higher crossover can work better because you are getting into a more linear range for both the sub but especially the mains and it always works better to crossover where both drivers are working linearly (another reason for steeper xover slopes).

 

[Keith_W]

Also, use 1/6 or 1/12 smoothing, not psychoacoustic smoothing. Re: that dip above 10kHz, please make sure it is not a measurement error. Read this.

 

[dualazmak]

Also, use 1/6 or 1/12 smoothing, not psychoacoustic smoothing. Re: that dip above 10kHz, please make sure it is not a measurement error. Read this.

In my post #1,009 on my project thread, I wrote;
As you can observe in Fig.16, I do not like, I do not apply, too-much-smoothing on Fq-SPL spectrum which hides-out various room modes. I would rather prefer common smoothing factor (FFT size, in this case) throughout 20 Hz - 20 kHz which well visualizes various room modes.

Spoiler: Dr. Floyd Toole wrote...

In the end of Dr. Toole's wonderful post here, he wrote:
Don't worry about little ripples. When I see exceptionally smooth high-resolution room curves I strongly suspect that something wrong has been done. The measurement microphone is no substitute for two ears and a human brain.

And in his post here, Dr. Toole kindly wrote responding to my inquiry:
If properly done both swept tone and noise analysis should give identical answers. It is a choice. The principal difference is in the heating of the drivers in sustained tests at high sound levels - power compression. Low frequencies require longer averaging times.

 

[Robbie010]

Also, use 1/6 or 1/12 smoothing, not psychoacoustic smoothing. Re: that dip above 10kHz, please make sure it is not a measurement error. Read this.

Thanks.

The high end roll-off is as expected when compared to the near-field measurements of my tweeters, I think we touched on this issue earlier in the thread.

After trying everything and also reaching out to the manufacturer, it seems they are knackered, at this stage they are just expensive paperweights:

New tweeters should be here tomorrow.

 

[3ll3d00d]

Just to prove there are as many opinions as posters…. I don’t use any smoothing when looking at subwoofer and its integration with a woofer. Only once you look beyond this range (to assess the overall curve) is any smoothing necessary. In particular octave smoothing can make dips look worse (mostly sharp dips can be ignored for dsp) and peaks look better (is harder to correctly position a cut when there is smoothing)