Sealed versus Ported Bass, can the difference be measured?

[Paul McNeil]

I don't know what you are talking about. You have two subs on the RIGHT connected with a Y-cable, and ANOTHER sub on the right on a separate channel?? According to your diagram:

The diagram is correct, I misspoke, sorry.

 

[Paul McNeil]

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

Correct.

had a quick look at the Marantz AV10 manual and I see it has four subwoofer outputs at the back. Whether these are on separate DAC channels, I have no idea. So I don't know why you are using a Y-cable when you have enough subwoofer outputs.

Because, probably wrong, I wanted the AV10 to give equal weight to each side, two 13s (one inch apart) and one 17, with big amps.

 

[Paul McNeil]

Unfortunately from here on, I can't help you any more. To me those AVR's are DSP black boxes where measurements go in, it does its mysterious thing, and results come out. I really, really, hate them. I don't like software making decisions for me, particularly when I can see with my own eyes that the software is screwing it up. I want to bypass the software decisions and make it do what I want, but those AVR's typically won't let me. And it boggles my mind that a $10k high end AVR expects you to use this piece of junk to take measurements:

I'm sorry to hear it, that you can't help anymore, but you already have thanks. I hear you but cannot follow.

 

[Paul McNeil]

It is very likely that the reason you have bad results is because you have made an error in your measurements or your DSP settings. M

Oh, likely!

 

[Paul McNeil]

If you want to improve the DSP of your system, you'll have to ask some people who know how to use AVR's and Dirac. It is very likely that the reason you have bad results is because you have made an error in your measurements or your DSP settings. Maybe someone else on ASR knows, or someone in a HT forum may have more of a clue

I understand, and thanks again, Keith_W.

 

[ryanosaur]

The AV10 and AV20 both feature 4 independent Sub Out.

 

[Paul McNeil]

The AV10 and AV20 both feature 4 independent Sub Out.

YEP!

 

[Keith_W]

1. Your subs are very poorly time aligned. Since your L sub and L speaker are on the same DAC channel, you have no way of fixing this. The ONLY solution is to put them on separate DAC channels and delaying the L speaker by about 15ms to match the sub. I say "about 15ms" because we don't know what the actual delay is, we need special procedures to determine that.

When I wrote this, I forgot / did not know you were running an AV10 with four separate output channels for subs. 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.

Anyway, now you know what to look for. I'll bow out of this thread and leave you to go talk to some Dirac experts.

 

[3ll3d00d]

Keith, Here are the files. It looks to me as if the same Step Response problem is present with the subs only (both them). These are time and SPL (80htz) aligned.

fwiw it's much easier to understand if you name each measurement clearly

you've measured the sub with the high pass filter in place still? and yet the right sub has a gigantic peak at 125Hz and multiple large spikes beneath that? it's really strange. It's also better to measure sub full range (and without a high pass filter or with it moved as high as possible) so you can actually see the response properly. Definitely would experiment with positioning and use 3 subs as 3 separate subs.

 

[kyuu]

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.

Technically speaking, you can present multiple subs to Dirac on the same channel as long as you have aligned them with some other DSP system first. I'm assuming you have not done so, and also I don't see the point when you have DLBC and enough channels on the AVR.

 

[Flaesh]

I'm sure the drivers were NOT designed for sealed operation.

How did you find out? Do you have the TS parameters of the drivers?
For example, here are drivers (Q .29) not intended for sealed operation in an infinite baffle without any equalization:

Here are the same drivers in sealed boxes, in another room and used slightly differently, also without any equalization:

 

[Paul McNeil]

When I wrote this, I forgot / did not know you were running an AV10 with four separate output channels for subs. 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.

Anyway, now you know what to look for. I'll bow out of this thread and leave you to go talk to some Dirac experts.

Where do I find these 'Dirac experts', and thanks for that.

 

[Paul McNeil]

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.

Technically speaking, you can present multiple subs to Dirac on the same channel as long as you have aligned them with some other DSP system first. I'm assuming you have not done so, and also I don't see the point when you have DLBC and enough channels on the AVR.

Yes, I'll try, but these subs were millimeters apart, Were they not one! I'll try, thanks.

 

[Paul McNeil]

How did you find out? Do you have the TS parameters of the drivers?
For example, here are drivers (Q .29) not intended for sealed operation in an infinite baffle without any equalization:
View attachment 463438
Here are the same drivers in sealed boxes, in another room and used slightly differently, also without any equalization:
View attachment 463440

Hey, addicted to fun and learning, I haven't got a clue what is your point!

 

[Paul McNeil]

All, I will try the three independent sub output from the AV10. I hope that I am wrong, and it will not make any difference, for two subs inches, one inch, apart.

 

[ryanosaur]

Where do I find these 'Dirac experts', and thanks for that.

I’m certain there are some here, but there is also a dedicated thread over at AVS. It wouldn’t surprise me if it is very long, but you should check it out and read a bunch starting at post 1.

https://www.avsforum.com/threads/dirac-live.3137722/?post_id=59508402#post-59508402

Also… definitely absolutely run your subs to individual channels, always.

The only reason to use a Y is because you have too many to run separately, or possibly if you have two like subs colocated or set up perfectly symmetrical in a symmetrical room... Which is realistically never. And then that leaves introducing a MiniDSP Flex as suggested previously.

for two subs inches, one inch, apart.

In many ways, it shouldn't as these should qualify as colocated, but as I wrote above...
PS: An inch can matter

 

[Flaesh]

Hey, addicted to fun and learning, I haven't got a clue what is your point!

Hey, member!) I haven't got a clue what method you use for determining of what drivers are intended for.
My point is stated in the link in the signature.
See also Room gain thread.

 

[Paul McNeil]

I’m certain there are some here, but there is also a dedicated thread over at AVS. It wouldn’t surprise me if it is very long, but you should check it out and read a bunch starting at post 1.

https://www.avsforum.com/threads/dirac-live.3137722/?post_id=59508402#post-59508402

Also… definitely absolutely run your subs to individual channels, always.

The only reason to use a Y is because you have too many to run separately, or possibly if you have two like subs colocated or set up perfectly symmetrical in a symmetrical room... Which is realistically never. And then that leaves introducing a MiniDSP Flex as suggested previously.


In many ways, it shouldn't as these should qualify as colocated, but as I wrote above...
PS: An inch can matter

Right, of course an inch can matter! And I'll test this, with cable...

 

[Paul McNeil]

Hey, member!) I haven't got a clue what method you use for determining of what drivers are intended for.
My point is stated in the link in the signature.
See also Room gain thread.

Thanks.

 

[Paul McNeil]

Hey, member!)

Yeah, low status guy. But here to learn.