How to group multiple subwoofers, for one TTD correction, but different delays.

[Johnny Jensen / JJAZ]

Hi All,

I have finally started testing of the Audiolense suite, and have trouble settings my subwoofers up the way I want.

I have 4 subwoofers, on 3 amplifier channels. Two of the subwoofers are equidistant to the MLP and thus share the same amplifier channel.

My goal (and what I do today using RePhase and JRiver) is to make one FIR filter for the entire subwoofer group, but each subwoofer channel should have its own delay.

So, first the delays should be set individually for each subwoofer channel, and then a common correction filter for the entire subwoofer group.

Is this possible in Audiolense (I believe Bernt wrote that it can be done, a few years ago), and if so, how?

To visualize what I want (as it might not be easy to understand), here is a picture of the correction+routing I want to make:
Subwoofer Routing

Greetings from Denmark

Johnny

[Omid Mostachfi]

Hi Johnny,

If I understand correctly, you want all 4 subs to play in unison as 1 single sub, so you apply 1 single FIR to all 4? If so, you could use REW to measure the relative delay of each sub, and go in JRiver under 'DSP settings, parametric equalizer, delay' and set the right delay in each of the 3 sub channels. Then when you do your audiolense measurement send the signal via JRiver. Audiolense will play all 4 subs at the same time (with the right delay) and generate a single FIR. I'm not sure if the extra step through JRiver might cause an error in the sweep, though.

An alternative approach would be to have audiolense generate 3 FIRs correcting both timing delay and frequency response for each sub individually.

You would setup the speakers as follows below. Hope this helps.

Omid

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[Johnny Jensen / JJAZ]

Hi Omid,

Thanks a lot for the answer. Yes, you understood it correctly :)

I thought of something similar to your approach.

If I do all of my measurements through JRiver, and that should indeed be doable, I should be able to measure each sub independently with Audiolense to first find the delays. After that I can set the delays in JRiver, and group the subs with the "Parametric Equalizer" (JRiver should really find a more suitable name for that tab), then I can measure all 4 together with Audiolense.

It is very similar to your suggestion, the only difference is to measure the delay with Audiolense instead of REW.

Perhaps I should mention the reasoning for my need. Two of my subwoofers (1 & 2 on the drawing) has a deep null at app. 100Hz in the MLP. But, when I use all 4 subs (time aligned to MLP) that null is almost gone. Therefore the correction needed is a lot less, and in my opinion better, when using one common correction filter for all 4 subs. Also, I prefer putting the same strain on all the woofers, so they run out of juice at the same time :)

Drawing of subwoofer positions: Subwoofer positions

My subwoofers are a little out of the ordinary.

Subwoofer 1: A vertical tower with 7x 10"

Subwoofer 2: A vertical tower with 8x 10"

Subwoofer 3: A horisontal "tower" with 7x 10"

Subwoofer 4: A vertical tower with 6x 10"

Greetings from Denmark

Johnny

[Bernt Rønningsbakk]

You can bundle all three subs in a multichannel subwoofer in Audiolense. A sub with three drivers. No crossover since you will run the three in parallel. Each sub will first be individually corrected and then the total will be corrected.

 

Mvh,

Bernt

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[Johnny Jensen / JJAZ]

Hi Bernt,

Interesting feature.. But, if I understand your proposal correctly, Audiolense will still create (and use) individual correction filters for the subwoofers, and then apply an extra common correction. And, I want to avoid the individual correction.

If it makes individual corrections, why is there then a need for a total correction as well?

Or, did I misunderstand you?

Greetings from Denmark

Johnny

[Bernt Rønningsbakk]

Please see response below

 

Mvh,

Bernt

 

From: audio...@googlegroups.com [mailto:audio...@googlegroups.com] On Behalf Of Johnny Jensen / JJAZ
Sent: mandag 7. desember 2020 10:27
To: Audiolense User Forum
Subject: Re: [audiolense] How to group multiple subwoofers, for one TTD correction, but different delays.

 

Hi Bernt,

 

Interesting feature.. But, if I understand your proposal correctly, Audiolense will still create (and use) individual correction filters for the subwoofers, and then apply an extra common correction. And, I want to avoid the individual correction.

 

 

[BR:] Audiolense can’t do that I’m afraid. But you will get very close to what you’re looking for if you try what I suggested. It could even work better than what you are envisioning.

If it makes individual corrections, why is there then a need for a total correction as well?

[BR:] Mostly because the acoustics will hardly ever allow for perfect corrections. So we need a global correction for the best possible speaker driver interaction. And often it is best to do time domain correction is only done on the whole speaker.

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/9c8c3c90-5868-43cb-8978-5e9084beb38an%40googlegroups.com.

[Johnny Jensen / JJAZ]

Both methods are worth a try, thanks a lot. I really need to get the girlfriend and kids out of the house for an evening or two, so I can tinker with the setup. Corona doesn't make it easier to get time alone for deep diving into the nerdy hobbies :-/

[Omid Mostachfi]

If you go with the unison model, you may want to phase align your 4 subs(if your subs have a phase alignment option). Then you could also phase align your subs to your speakers (although this latter adjustment will probably be done by AL if you don't do it yourself). The way I do it is like this: I play a sine wave at the subwoofer crossover frequency on 2 subs (or sub and main speaker) and I change the phase to get the loudest dB measurement on my SPL meter.

Let us know how it turns out.

Omid

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/e6f1459f-bc69-48ce-ac5b-3a81bd29173fn%40googlegroups.com.

[Johnny Jensen / JJAZ]

Bernt, something else.

How do I make the channel routing for a 6.x system? In the "Speaker Setup and Playback Formats -> Play Back Format and Channel Routing" tab, I can only choose between 2.0 and 5.1. How do I route the rear-channel(s) ?

On Monday, December 7, 2020 at 11:14:30 AM UTC+1 BerntR wrote:

[Bernt Rønningsbakk]

It depends on how you want to use your 6 speakers. You can pretty much remap any format as you like to your speaker system.  

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/ac872181-1fb5-426c-af74-4b4c2562c9f4n%40googlegroups.com.

[Johnny Jensen / JJAZ]

Hmm.. But the rear channels are not in the routing matrix in Audiolense?

My setup is like this:

Left Front: 2 channels (Audiolense XO routing <100Hz to subs, and HP/LP 250Hz)

Right Front: 2 channels (Audiolense XO routing <100Hz to subs, and HP/LP 250Hz)

Center: 1 channel (Audiolense XO routing <100Hz to subs)

Left Surround: 1 channel (Audiolense XO routing <100Hz to subs)

Right Surround: 1 channel (Audiolense XO routing <100Hz to subs)

Rear Center Surround: 1 channel (Audiolense XO routing <100Hz to subs) This one I can't figure out how to route in Audiolense?

Subs1+2: 1 channel

Sub3: 1 channel

Sub4: 1 channel

[Bernt Rønningsbakk]

For a 5.1 playback you have to decide whether you want to use the back speaker or not. You can e.g. feed it with the side channels’ signal at the quantity you desire.

 

You can also create your own matrix. E.g. 6.1 and 7.1.  Add all the input channels that belongs to the desired format and then map to your own speaker setup.

 

Which playback formats do you need routing for? Start there.

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/c1997ae2-4dd7-4e7e-b9a2-16f4c62ae54bn%40googlegroups.com.

[Johnny Jensen / JJAZ]

I want 7.1 playback downmixed to 6.1 (summing the two rear channels).

Perhaps I still don't understand you, but I cannot find the rear channels in the "Play Back Format and Channel Routing". It seems to support up to 5.1, and therefore the rear surround channels are missing.

Please look at my screenshots and let me know what I am doing wrong. In "Channel Routing" you can see that only up to 5.1 is available for me, and there are no rear channels in the matrix.

Also, how do you embed the pictures directly in the post?

Speakers

Cross Over Configuration

Channel Routing

Measurement

[Bernt Rønningsbakk]

1)      Chose 5.1 playback format.

2)      Press “new / edit current” button to the left

 

3)      Add back left and back right, save

4)      Enter 1.0 from back left to back center and from back right to back center

 

Voila!

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/8c08c785-b2c6-452a-a6b7-e48fd40efebfn%40googlegroups.com.

[Johnny Jensen / JJAZ]

Fantastic, thanks a lot.. (and sorry, I should have discovered that feature by myself)

Then I should be ready to measure this evening, and if all looks good I will order a license.

I am still worried about the subwoofer part, as I have pretty strict wishes for how I want it to work :) But, hopefully I can coax Audiolense to do what I want, though it might require some manual tinkering with the convolver cfg.

[Johnny Jensen / JJAZ]

I still need to request for Audiolense to allow a subwoofer setup with individual delay for each subwoofer, and one global EQ/TTD.

My case may be special, but I don't think so.

I have four subwoofers (totalling 28x 10" drivers), right now coupled to three amplifier channels. The two front subwoofers are equidistant to MLP, and therefore share an amplifier channel.

Here are the three individual subwoofer channels, measured in MLP:

https://www.jjaz.dk/privat/hifi/audiolense/2020-12-30_individual_subs.jpg

As can be seen they will require a lot of EQ to be linear from 18-100Hz.

Here they are combined with 0 delay between them:

https://www.jjaz.dk/privat/hifi/audiolense/2020-12-30_combined_subs_0-delay.jpg

This is also pretty horrible, I think.

Here they are, with delays that make them more or less equidistant:

https://www.jjaz.dk/privat/hifi/audiolense/2020-12-30_combined_subs_delay.jpg

I would much prefer to EQ/TTD this combination, instead of the three of them individually. This one requires way less gain to be lost in the filters.

Therefore, please consider implementing this feature, even though I know you do like to always make individual corrections.

Greetings from Denmark

Johnny

[Bernt Rønningsbakk]

Duly noted.

 

Today you can do individual delay for each subwoofer, individual frequency correction for each, and one global EQ/TTD. Yes, there is a difference, but this may work just as fine. Have you tried it?

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/8eb72c25-3616-4e5a-98ef-d7a3362fb679n%40googlegroups.com.

[Barry]

Hi all

Recommend signing up to the new Audiolense forum here:

https://www.avnirvana.com/forums/audiolense-user-forum.89/

And saying hello in the hello thread.

[Johnny Jensen / JJAZ]

I wrote a reply here about an hour ago, but now it says "Message was deleted" ???

[Johnny Jensen / JJAZ]

I will make a shorter reply this time, as my previous reply was deleted ?!?

Yes,  I have tried that option. But in my case it robs the system of 20dB gain, which is more than I am willing to give up. Using individual delay and one global frequency/TTD correction, the cost is 10dB of gain. Also 20dB correction in the subwoofer frequencies puts a lot more strain on the subwoofers and amplifiers.

On Thursday, December 31, 2020 at 10:52:48 AM UTC+1 BerntR wrote:

[Bernt Rønningsbakk]

I don’t know what happened to your post. For the record I only delete spam and I can’t remember the last time it happened.

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/61dad299-1e32-4429-86a2-96ec52832ee6n%40googlegroups.com.

[Bernt Rønningsbakk]

Hi Johnny,

 

I would like to look at your situation. Could you mail me the al.ini file that sits in the program data folder? I assume there will be a measurement there.

 

Mvh,

Bernt

 

From: audio...@googlegroups.com [mailto:audio...@googlegroups.com] On Behalf Of Johnny Jensen / JJAZ
Sent: lørdag 2. januar 2021 16:28
To: Audiolense User Forum
Subject: Re: [audiolense] How to group multiple subwoofers, for one TTD correction, but different delays.

 

Hi Bernt,

 

I have tried that option, but it robs my system of more than 20dB of gain, which is a lot more than I am willing to give up. With individual delay, and one global frequency correction, I loose app. 10dB of gain.

Also, boosting the subwoofers by 20dB at some frequencies is a lot of extra demand on both subwoofers and amplifiers. While I do have quite a lot of cone area and amplifier power, I am not keen on using it like that.

 

On Thursday, December 31, 2020 at 10:52:48 AM UTC+1 BerntR wrote:

To view this discussion on the web visit https://groups.google.com/d/msgid/audiolense/4d6a08c9-58e0-4c5d-af00-8cef99ebeb46n%40googlegroups.com.

[Johnny Jensen / JJAZ]

Hi Bernt,

Of course, though I might have to make a new measurement, as I honestly don't remember what the last thing I tried was, hmm.. Probably some WASAPI testing :-)

I did not not manage to find your complete email address?

Greetings

Johnny