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TOPIC: nanoAVR DL bass management issue

nanoAVR DL bass management issue 1 year 9 months ago #17805

  • sheraz
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I'm very interested in buying nanoAVR DL but have a major concern with bass management. Since bass management is after room correction in chain, it has good chances to cause the issues. Here is the scenario in detail

If your left speaker had a spike at 50hz (say +20db higher than rest of the FR). This is what will happen with Dirac Live Correction:

1) Reduce left channel 50hz by 20db with a filter.
2) Apply bass management with the bass from the left speaker now being 20db lower than it should.
3) Subwoofer plays left channel 50hz freq. 20db lower than intended. (Subwoofer has no 20db spike at 50hz)

Another way to put it is as follows

"Your centre speaker has a 6dB peak at 50Hz, so you EQ that channel with a 6dB cut at 50Hz. You low pass that channel at 80Hz and combine the bass with similarly low-passed bass from other channels (and LFE).

Your subwoofer signal now has a 6dB dip at 50Hz. What if your sub isn't placed right below the centre speaker; i.e., what if the sub is in a location that doesn't cause it to have a 6dB peak at 50Hz? What is that 6dB cut doing there?

You've unnecessarily introduced a 6dB dip in the bass response that could have been avoided by EQing the subwoofer signal itself (and not EQing each channel being fed to the subwoofer). "

Can you please clarify is that is correct and this is how Dirac for nanoAVR works? If yes Then isn't that a big issue with NanoAVR heing in chain before bass management?

thx.
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nanoAVR DL bass management issue 1 year 9 months ago #17806

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Hi there, that isn't how it works. With your bass management turned on in the AVR, the nanoAVR DL will "see" and therefore equalize the combined response. As far as the nanoAVR DL is concerned, the crossover, sub, and speaker are all "one speaker."

Hope that helps :)
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
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nanoAVR DL bass management issue 1 year 9 months ago #17809

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john.reekie wrote:
Hi there, that isn't how it works. With your bass management turned on in the AVR, the nanoAVR DL will "see" and therefore equalize the combined response. As far as the nanoAVR DL is concerned, the crossover, sub, and speaker are all "one speaker."

Hope that helps :)

Thanks for your response. So that I understand clearly your response, let's have a scenario to understand it better.
Current System: 5.1
Cross-Over set in ave: 80.
Assumptions:
Left Speaker has a peak of 10db at 50hz
Right speaker has a peak of 5db at 50hz
Center has a dip of 4db at 40

Let's not worry about sorround :)

Process:
1 - Set cross over in avr before running Dirac to 80.
2 - Make sure all speakers are set to small in avr.
3 - Run Dirac calibration.

During calculation, Dirac will sum all the speakers below 80 (cross-over) as per what you explained. In this case, the end result before filter will be
A peak of 15db at 50hz (Left+Righ)
A dip of 4db at 40hz (Center).

Dirac will create 2 filters. First one to get rid of 15db peak and 2nd to get rid of 4db dip.
End result: a flat response below 80hz for subs.

Is that correct?

thx.
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nanoAVR DL bass management issue 1 year 9 months ago #17810

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No, that's not correct :)

I did not mean that Dirac will sum all speakers. By "combined" response I meant the combined response of one speaker and the subwoofer (and the bass management filters).

It does not matter if your left speaker has a 10 dB peak at 50 Hz before you turn on bass management. What matters (to Dirac) is what the response is with bass management turned on. Dirac will "see" that response on each channel, with bass management on and therefore including the filters and subwoofer, and correct for it.

Hope that is clearer - ?

;)
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
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-> Have you posted a screenshot?
-> Have you posted your config file?
Last Edit: 1 year 9 months ago by john.reekie.
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nanoAVR DL bass management issue 1 year 9 months ago #17812

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john.reekie wrote:
No, that's not correct :)

I did not mean that Dirac will sum all speakers. By "combined" response I meant the combined response of one speaker and the subwoofer (and the bass management filters).

It does not matter if your left speaker has a 10 dB peak at 50 Hz before you turn on bass management. What matters (to Dirac) is what the response is with bass management turned on. Dirac will "see" that response on each channel, with bass management on and therefore including the filters and subwoofer, and correct for it.

Hope that is clearer - ?

;)

Almost :)
So after the correction, I'm going to rewrite the scenario. I really want to get it right since I"m very excited about this product and if there are no bass management related issues, I"ll order one in a heart beat ;)

My understanding is that below cross-over, only sub produces the sound. That is, No other speaker will produce any sound but Sub. Is that correct?
Back to the scenario case with some modifications (if you don't mind :) )

Current System: 5.1
Cross-Over set in ave: 80.
Assumptions:
Left Speaker has a peak of 10db at 50hz
Right speaker has a peak of 5db at 50hz
Sub has no issues at 50hz.
Center has a dip of 4db at 40
Sub as a peak of 3db at 40.

Let's not worry about sorround :)

During calculation:
1- Dirac will Run test for Left+Sub below 80. Sub has no issue at 50Hz but Left does(10db peak). In this case Dirac will apply a 10db filter for Left + Sub.
2- Dirac will Run test for Right+Sub below 80. Sub has no issue at 50Hz but Right does(5db peak). In this case Dirac will apply a 5db filter for Right + Sub.
3- Dirac will Run test for Center+Sub below 80. Sub has an issue at 40Hz (3db peak) and Right does(4db dip). In this case Dirac will apply a 1db gain filter for Center + Sub.

Before calibration Sub:
40 Hz: A dip of 3 db
50 Hz: Nothing wrong
After calibration Sub:
40 Hz: A peak of 1 db (filter of 4db was applied for sub+center)
50 Hz: A peak of 15db (2 filters were applied. 1 for L+S and another for R+S)
After calculation, We have 2 filters. 2 At 50Hz (one for left and one for right) and one at 40Hz(center+sub).

End Result:
@40Hz Dirac improved sub response by reducing 3db dip with 1db gain.
@50Hz Dirac messed up sub response. It had no issue but since Dirac measured it with speaker, it introduced filters due to speakers response.

Can you please correct my assumptions in line if that's possible.
thx.
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nanoAVR DL bass management issue 1 year 9 months ago #17813

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sheraz wrote:
My understanding is that below cross-over, only sub produces the sound. That is, No other speaker will produce any sound but Sub. Is that correct?

Mostly correct :) The sub and the speakers have, in effect, a crossover. So there is not a sudden transition where below 80 Hz sub plays everything and above 80 Hz the speaker plays everything. Instead, there is a transition between them, a region around 80 Hz where both the sub and the speaker are playing.
Back to the scenario case with some modifications (if you don't mind :) )

Current System: 5.1
Cross-Over set in ave: 80.
Assumptions:
Left Speaker has a peak of 10db at 50hz
Right speaker has a peak of 5db at 50hz
Sub has no issues at 50hz.
Center has a dip of 4db at 40
Sub as a peak of 3db at 40.

OK, but when you say the Left Speaker has a peak of 10db at 50hz, that is without the bass management, right? When you turn on bass management, the high pass filter on the left speaker will reduce output from the speaker below 80 Hz (technically the reduction starts a bit above 80 Hz). So with bass management turned on, the left speaker will not have a 10 dB peak any more. There may be some effect still, but not 10 dB and it will be amongst all the peaks and dips in the sub response...
During calculation:
1- Dirac will Run test for Left+Sub below 80. Sub has no issue at 50Hz but Left does(10db peak). In this case Dirac will apply a 10db filter for Left + Sub.

No. With the bass management turned on, Dirac will not apply a 10 dB correction at 50 Hz, because it will not "see" a 10 dB peak there. At that frequency, mostly it will be the sub playing. Dirac will correct for the combined response of sub and speaker, with bass management filters turned on. It cannot see a 10 dB peak from the left speaker, because the bass management makes it not there any more.
Before calibration Sub:
40 Hz: A dip of 3 db
50 Hz: Nothing wrong
After calibration Sub:
40 Hz: A peak of 1 db (filter of 4db was applied for sub+center)
50 Hz: A peak of 15db (2 filters were applied. 1 for L+S and another for R+S)
After calculation, We have 2 filters. 2 At 50Hz (one for left and one for right) and one at 40Hz(center+sub).

No. As above, the 10 dB peak is not there anymore because of bass management. Also, Dirac does not add the correction for two channels. It just does each one separately.
End Result:
@40Hz Dirac improved sub response by reducing 3db dip with 1db gain.
@50Hz Dirac messed up sub response. It had no issue but since Dirac measured it with speaker, it introduced filters due to speakers response.

Nope :)
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?
Last Edit: 1 year 9 months ago by john.reekie.
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nanoAVR DL bass management issue 1 year 9 months ago #17815

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Your post did make me feel better but here are the concerns that were raised.
Having BM after: at this point optimization already fails because the test signal goes through bass management and Dirac measures the wrong thing. For example it will measure L plus sub when Dirac should measure just L
RC applies a filter to each channel. In bass management these preprocessed channels are mixed together and are output from a speaker (here, the subwoofer) the individual RC filters aren't applicable to.
If the test signal for room correction goes through bass management then everything is already completely messed up. The test signal will be played by more than one speaker (L and sub for example) when only one speaker should be measured at a time.
Lets assume the room correction filters have been created correctly but they are applied before bass management. This is another source of error. The channel signals get equalized and altered by the room correction filters according to the speaker they are assigned to but now they get mixed together in bass management and are routed to the sub. In other words, the equalized signal for let's say the left speaker is reproduced by a speaker for which the equalization isn't valid, namely the sub. The result is a distorted signal.
Last Edit: 1 year 9 months ago by sheraz.
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nanoAVR DL bass management issue 1 year 9 months ago #17816

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I'm not a Dirac owner (yet), but the way I understand it, you have to tell the software about your speaker configuration in the initial setup phase. If you're using a separate, single subwoofer for example, Dirac will then be aware of this and base its measurements and corrections accordingly.

I think I understand your concerns here. May I make a humble suggestion? At this point the Dirac product has been scrutinized pretty closely by lots of users & reviewers. If the mis-measurement scenarios you describe were occurring, they would indeed represent a significant shortcoming, and so would have been pretty thoroughly picked apart and criticized by now. Since this is not happening, perhaps it's safe to assume that the system is not making these particular mistakes, and it's OK not to worry about it?

-- Jim
Last Edit: 1 year 9 months ago by Jim the Oldbie. Reason: The crux of the biscuit is the apostrophe.
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nanoAVR DL bass management issue 1 year 9 months ago #17817

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Jim the Oldbie wrote:
I'm not a Dirac owner (yet), but the way I understand it, you have to tell the software about your speaker configuration in the initial setup phase. If you're using a separate, single subwoofer for example, Dirac will then be aware of this and base its measurements and corrections accordingly.

I think I understand your concerns here. May I make a humble suggestion? At this point the Dirac product has been scrutinized pretty closely by lots of users & reviewers. If the mis-measurement scenarios you describe were occurring, they would indeed represent a significant shortcoming, and so would have been pretty thoroughly picked apart and criticized by now. Since this is not happening, perhaps it's safe to assume that the system is not making these particular mistakes, and it's OK not to worry about it?

-- Jim

Jim,
Concern is not about Dirac at all. It's more to do with wereh nanoAVR DL goes in the chain. The flow is Player --> nanoAVR DL --> AVR. Again concern has nothing to do with Dirac but how nanoAVR DL being before bass management handles the concerns.
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nanoAVR DL bass management issue 1 year 9 months ago #17818

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Hi sheras, we had a thread all about that a while ago, perhaps you could search for it? miniDSP rep is "devteam." I did not realize that was the thrust of your question.

If you really want to put bass management "before" Dirac, you can use a DDRC-88A, or a nanoAVR HD between the Player and nanoAVR DL (i.e two nanoAVR units). I'm not sure anyone has tried the latter, but I can't think of any reason it wouldn't work...

Cheers :)
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
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nanoAVR DL bass management issue 1 year 9 months ago #17819

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Can you provide the link to that discussion? Also you are correct about DDRC-88A. Only issue is that it also needs an amp in the chain. That's another 1k minimum we are adding :(. Also can you please reply to my last few questions I posted plz? That would be a great help. I"m trying to narrow down if there really is an issue having Dirac before bass management. If its not then getting a nanoAVR DL is best for me as I"d have to spend 700.00 instead of 2,000.
Only if miniDSP had a 10 days return policy. I would have then bought it and tried it out myself. Buying a device for 700 and then finding out that its not working properly is a bummer.

thx.
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nanoAVR DL bass management issue 1 year 9 months ago #17822

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sheraz,

Try to understand what bass management is and how it works and it should become very obvious why the only correct location for EQ is AFTER bass management:

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Last Edit: 1 year 9 months ago by markus.
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nanoAVR DL bass management issue 1 year 9 months ago #17844

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sheraz wrote:
Concern is not about Dirac at all. It's more to do with wereh nanoAVR DL goes in the chain. The flow is Player --> nanoAVR DL --> AVR. Again concern has nothing to do with Dirac but how nanoAVR DL being before bass management handles the concerns.

Not to put too fine a point on it, but in this case, for all intents and purposes, nanoAVR DL _is_ Dirac. So the question really is how _Dirac_ handles the bass management concerns. Again, I'm not an owner, but from what I've read about nanoAVR DL, it looks like its Dirac implementation (if set up correctly) has enough awareness of its position in the signal path to get things done properly.

-- Jim
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nanoAVR DL bass management issue 1 year 9 months ago #17846

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markus wrote:
sheraz,

Try to understand what bass management is and how it works and it should become very obvious why the only correct location for EQ is AFTER bass management

I think that is exactly the point sheraz is trying to make. :o) But is this always true? There is a fair amount of magnitude & phase correction that can be done upstream from bass management. RePhase has among other features a 'global' curve that would be an example of this, if I understand it correctly. Also, nanoAVR DL's Dirac is made aware of the speaker config during setup. If it's smart enough, it should still be able to blend things properly even though it can't address & test each speaker separately? How is this different from its inability to test mids separately from tweets, for example?

-- Jim
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nanoAVR DL bass management issue 1 year 9 months ago #17847

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Jim the Oldbie wrote:
sheraz wrote:
Concern is not about Dirac at all. It's more to do with wereh nanoAVR DL goes in the chain. The flow is Player --> nanoAVR DL --> AVR. Again concern has nothing to do with Dirac but how nanoAVR DL being before bass management handles the concerns.

Not to put too fine a point on it, but in this case, for all intents and purposes, nanoAVR DL _is_ Dirac. So the question really is how _Dirac_ handles the bass management concerns. Again, I'm not an owner, but from what I've read about nanoAVR DL, it looks like its Dirac implementation (if set up correctly) has enough awareness of its position in the signal path to get things done properly.

-- Jim

Dirac Live has no knowledge where in the signal chain it operates. It sends a test signal downstream and measures the acoustical response. Then it creates a correction filter based on that response. It does that for each of its output channels.
Last Edit: 1 year 9 months ago by markus.
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