Sealed versus Ported Bass, can the difference be measured?

[Paul McNeil]

This may be the cause of your extremely wonky impulse response,

I hope you are right about the 'extremely wonky impulse response', hmmm, as I said I will test, I have the cables.

 

[Paul McNeil]

Since your subs are on individual channels, it SHOULD be possible for you to fix this with your existing equipment. The big question is, why didn't Dirac do it for you. I mean, a 15ms subwoofer delay is a WHOPPING amount of delay for a DSP system.

Yes, I agree, why did Dirac not do this? Dirac could not know if it was one or two subs, 2.5 cm apart.

 

[Flaesh]

The ratio Fs\Qts has long been used to determine the suitability of a loudspeaker for different enclosure types (in anechoic conditions for a flat frequency response) of the driver. That's why I asked if you knew the TS parameters.
But at low frequencies in the room, everything is a little different.
Also, drivers with higher Qts are often used in commercial products for BR.

 

[kyuu]

Yes, I agree, why did Dirac not do this? Dirac could not know if it was one or two subs, 2.5 cm apart.

That's exactly the problem, I think.

Also, it seems like you're looking at how far apart the two subwoofer enclosures are, but of course the edge of the enclosure is not the acoustic center. Those cylinder subs are 16.6" in diameter, if I found the correct specs, so assuming the acoustic center aligns with the physical center then the two subs are actually 17.6" apart (including your stated 1" spacing).

 

[Paul McNeil]

The ratio Fs\Qts has long been used to determine the suitability of a loudspeaker for different enclosure types (in anechoic conditions for a flat frequency response) of the driver. That's why I asked if you knew the TS parameters.
But at low frequencies in the room, everything is a little different.
Also, drivers with higher Qts are often used in commercial products for BR.

Interesting.

 

[Paul McNeil]

That's exactly the problem, I think.

Also, it seems like you're looking at how far apart the two subwoofer enclosures are, but of course that's not the acoustic center. Those cylinder subs are 16.6" in diameter, if I found the correct specs, so assuming the acoustic center aligns with the physical center, then the two subs are actually 17.6" apart (including your stated 1" spacing).

Yeah, my next move is separate cabling, and DSP, I think I've already said that...

 

[Paul McNeil]

That's exactly the problem, I think.

Also, it seems like you're looking at how far apart the two subwoofer enclosures are, but of course the edge of the enclosure is not the acoustic center. Those cylinder subs are 16.6" in diameter, if I found the correct specs, so assuming the acoustic center aligns with the physical center then the two subs are actually 17.6" apart (including your stated 1" spacing).

Message received, thanks.

 

[Flaesh]

But here to learn

And you will become Addicted to Fun and Learning, namesake)
I don't know how much I need to write before the next status.
IMO you can try to plug holes in old subwoofers.

 

[Paul McNeil]

And you will become Addicted to Fun and Learning, namesake)
I don't know how much I need to write before the next status.
IMO you can try to plug holes in old subwoofers.

I want to improve the sound of my system. I'm not interested in status, I'm too old for that! But go for it, plug holes in in old subwoofers.

 

[levimax]

While not a DIRAC expert I have spent almost a year trying to get DLBC to work correctly with multiple subs and as I mentioned it appears to be working now with the latest update. Here are my thoughts:

1. As mentioned you need one channel for each sub.
2. Since each sub has individual DSP make sure each sub has the same settings according to the DIRAC instructions.
3. Rather than rely on "internet guides" with often contradictory instructions or your own intuition I highly recommend you download the latest DIRAC instructions, read through them carefully several times, and then follow them exactly. Errors, especially sub setup and setting the initial levels can throw the measurements off.

Good luck.

 

[Flaesh]

- this is D50. I would say that there is no D50 below 80 Hz.

- this is PET. Did I miss or forget the sub crossover frequency? They work quite late anyway.

 

[ryanosaur]

3. Rather than rely on "internet guides" with often contradictory instructions or your own intuition I highly recommend you download the latest DIRAC instructions, read through them carefully several times, and then follow them exactly. Errors, especially sub setup and setting the initial levels can throw the measurements off.

I don't disagree in principle. However there are many very skilled and educated people contributing to some of these conversations and shouldn't be ruled out completely.

Definitely agree that RTFM needs to always be applied to all situations involving DIRAC. It can be finicky even then, which is where getting to ask some other users can be helpful!

 

[3ll3d00d]

Wait a minute. You have 2 subs connected to the AVR via a Y cable? So two subs on one channel? To my understanding, you can't do that with Dirac. In order to properly align and correct multiple subs, they all need to be on individual channels. This may be the cause of your extremely wonky impulse response, which rather than being a weird reflection issue is actually two different implulses from two misaligned subs on the same channel.

he can do this without any problem if the subs are spaced close enough together (typically within 1/4 wavelength of the highest frequency they play),

@Paul McNeil said they are 1" apart which means they can indeed be treated as if they are a single sub. One caveat is that each sub has its own DSP and amp so make sure they are configured identically (easy to verify, just measure each one completely independently).

whether he gets a better result by running them separately in different locations is another Q, only one way to find that out (i.e. try it)

 

[levimax]

I don't disagree in principle. However there are many very skilled and educated people contributing to some of these conversations and shouldn't be ruled out completely.

I agree, when I said "Internet Guides" I was referring mainly to video's found online, not to wise individuals. Sometime the videos are OK but often times they can be out of date especially with DIRAC DLBC which is still being updated / developed and things have been changing.

 

[Salt]

I don't disagree in principle. However there are many very skilled and educated people contributing to some of these conversations and shouldn't be ruled out completely.

Definitely agree that RTFM needs to always be applied to all situations involving DIRAC. It can be finicky even then, which is where getting to ask some other users can be helpful!

I'm not that deep into DIRAC that I read the FM, but as I understood the theory behind the story was, that it (the DIRAC) tunes the sound at MLP automatically without any understanding of the user.
Seems my interpretation was wrong?

 

[levimax]

I'm not that deep into DIRAC that I read the FM, but as I understood the theory behind the story was, that it (the DIRAC) tunes the sound at MLP automatically without any understanding of the user.
Seems my interpretation was wrong?

DIRAC does do "automatic" tuning and you also have the flexibility to alter the FR of the filters as well. In order to do this it requires a series of measurements around the MLP as well as adjusting the levels of each speaker. These settings and measurements are done with a "wizard" which tries to be user friendly but if you are unfamiliar with the process it is easy to make mistakes and if you do make mistakes during the measurement process DIRAC will cheerfully create bogus filters for you. Nothing really "hard" about the process, just many chances to make a mistake.

 

[Salt]

DIRAC does do "automatic" tuning and you also have the flexibility to alter the FR of the filters as well. In order to do this it requires a series of measurements around the MLP as well as adjusting the levels of each speaker. These settings and measurements are done with a "wizard" which tries to be user friendly but if you are unfamiliar with the process it is easy to make mistakes and if you do make mistakes during the measurement process DIRAC will cheerfully create bogus filters for you. Nothing really "hard" about the process, just many chances to make a mistake.

Thanks for the reply that supports my understanding of DIRAC so far.

 

[ryanosaur]

I agree, when I said "Internet Guides" I was referring mainly to video's found online, not to wise individuals. Sometime the videos are OK but often times they can be out of date especially with DIRAC DLBC which is still being updated / developed and things have been changing.

Never waste life on a YT vid.
#words-to-live-by!

 

[thunderchicken]

All this talk about delay on subs is fascinating. Anyone else use wireless for subs? I noticed a huge amount of latency in the setup notes between two separate systems with two different brands of sub and wireless sets.

I have a Wiim doing auto room correction and sub integration with a Klipsch sub and Klipsch wireless. Hardwired, the mains only needed 15ms of delay. Wireless, they need 55! I went wireless for install and placement.

My Anthem/RSL kit did something similar but showed distance rather time, with similar amounts. The RSL replaced the Klipsch, and it seems like the RSL system is slower because the AVR went from thinking the sub is 19ft away to thinking it’s 35ft away. I think part of that delay is RSL’s DSP, but I thought it was neat to see it in real time. The RSL is within a few inches of where the Klipsch was.

Both setups sound awesome, so no issue there.

 

[Holmz]

…
Anyway, if you have four subs, according to Welti 2004 the subs should be positioned like this:

View attachment 463394

The second configuration is probably not possible given where the fireplace in your room is.
…

Are “chimney loaded” subwoofers not “a thing”?
(Sort of like a horn loaded, just done in brick.)