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TOPIC: Bass management on 2x4 question

Bass management on 2x4 question 1 month 3 weeks ago #28204

  • AustinJerry
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The original 88BM user guide in section 5.2 has the following instructions: "Bass management should be set up after Dirac Live calibration. This ensures that levels and delays are correct. Save your current configuration to a file before you begin to set up bass management. If, after setting up bass management, you wish to redo the Dirac Live calibration, reload this configuration file first. (This is because of a technical detail in the way that the DDRC-88BM processing interacts with the Dirac Live processing.)"

The current user guide states "Bass management should be set up after Dirac Live calibration. This ensures that levels and delays are correct."

This is unclear to me. My understanding is that the Dirac Live calibration results and the bass management configuration are entirely independent of one another. How can the Dirac levels and delays influence bass management?

And when the Dirac Live calibration is re-run, what configuration file should be reloaded first? And what is the interaction between Dirac Live and bass management?

Are the recommendations in the first quote no longer valid? My recommendation would be to re-word this section so its meaning is more clear.
Last Edit: 1 month 3 weeks ago by AustinJerry.
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Bass management on 2x4 question 1 month 3 weeks ago #28205

  • john.reekie
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I fail to see what is unclear about "Bass management should be set up after Dirac Live calibration."
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?
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Bass management on 2x4 question 1 month 3 weeks ago #28208

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john.reekie wrote:
I fail to see what is unclear about "Bass management should be set up after Dirac Live calibration."

The sentence itself is perfectly clear, John. What I don't understand is the reason why.

The Dirac Live calibration should be measuring the speakers and subs completely independent from bass management. And, as far as I know, nothing in the bass management configuration is dependent on the trims and delays that Dirac Live establishes. So what would make the statement more clear to me is an explanation for why the order (Dirac vs. BM) should make a difference, and what is the impact if the recommended order is not followed?

For example, after implementing bass management in the 88BM, I have run a number of fresh Dirac Live calibrations. I did not turn off bass management before doing so, nor did I reset everything to factory defaults. Does this mean I have a flawed configuration now?
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Bass management on 2x4 question 1 month 3 weeks ago #28209

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It says run a Dirac Live calibration before setting up bass management, not don't run a Dirac Live calibration after setting up BM.

(And no, those are not the same thing.)

Do a thought experiment (or a real one) where the levels of different speakers (pre Dirac or BM) are different.
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?
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Bass management on 2x4 question 1 month 3 weeks ago #28210

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john.reekie wrote:
It says run a Dirac Live calibration before setting up bass management, not don't run a Dirac Live calibration after setting up BM.

(And no, those are not the same thing.)

Do a thought experiment (or a real one) where the levels of different speakers (pre Dirac or BM) are different.

Sorry to be so thick, John, but what do speaker trims have to do with bass management?
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Bass management on 2x4 question 1 month 3 weeks ago #28211

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I didn't say anything about speaker trims.
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?
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Bass management on 2x4 question 1 month 3 weeks ago #28219

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john.reekie wrote:
I didn't say anything about speaker trims.

John, your responses on this forum are usually cordial and helpful. I aplologize if I have done something in the past to offend you. I have been a staunch supporter of MiniDSP products over the last several years, and I feel that my questions deserve a more respectful answer, not quick one-liners that don't address my lack of understanding.

So, can you please explain why one should run a Dirac Live calibration before setting up bass management? And what would be the impact if this recommendation were not followed?
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Bass management on 2x4 question 1 month 3 weeks ago #28224

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Jerry, I suggest you do a thought experiment to work through it for yourself. Or, a real one. If you set the analog gains in the system so that some speakers have significantly different level (e.g. on the Output&Levels screen) than others, that's probably the easiest way to do it.

You seem to be overcomplicating the whole thing in some way. Dirac Live changes levels and delays on its channels when you do the calibration (you know this). Any measurements injected "upstream" will "see" the effect of those.
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?
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Bass management on 2x4 question 1 month 3 weeks ago #28225

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john.reekie wrote:
Jerry, I suggest you do a thought experiment to work through it for yourself. Or, a real one. If you set the analog gains in the system so that some speakers have significantly different level (e.g. on the Output&Levels screen) than others, that's probably the easiest way to do it.

You seem to be overcomplicating the whole thing in some way. Dirac Live changes levels and delays on its channels when you do the calibration (you know this). Any measurements injected "upstream" will "see" the effect of those.

Sorry, John, your response makes no sense to me at all. I hope MiniDSP Support is monitoring this conversation and will weigh in with an explanation that I can understand. Thanks for your attempt at answering my question.
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Bass management on 2x4 question 1 month 2 weeks ago #28256

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john.reekie wrote:
Jerry, I suggest you do a thought experiment to work through it for yourself. Or, a real one. If you set the analog gains in the system so that some speakers have significantly different level (e.g. on the Output&Levels screen) than others, that's probably the easiest way to do it.

You seem to be overcomplicating the whole thing in some way. Dirac Live changes levels and delays on its channels when you do the calibration (you know this). Any measurements injected "upstream" will "see" the effect of those.

John, I posed my question to MiniDSP Support, and they acknowledged that the quoted passage in the current user guide is indeed in error.
The first beta implementation of the 88BM had the DL sweep signal generator at the input before BM (which would have been incorrect). The location of the signal generator has since been changed, and the Dirac Live calibration and the bass management settings on the 88BM are indeed independent.

A revised edition of the user guide will be released in the near future and will contain this correction.
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Bass management on 2x4 question 1 month 2 weeks ago #28258

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I'll try one last time: the "settings" are independent, but the values that are set by Dirac Live will change what you measure when you set up bass management.
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?
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Bass management on 2x4 question 1 month 2 weeks ago #28265

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john.reekie wrote:
I'll try one last time: the "settings" are independent, but the values that are set by Dirac Live will change what you measure when you set up bass management.

If by "what you measure" you mean the in-room reasponse as measured by a tool like REW, then of course the measurements will change. But that statement is in no way a response to my original question, which has now been answered to my satisfaction by MiniDSP Support. I consider this a closed conversation now.
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Bass management on 2x4 question 1 month 2 weeks ago #28266

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Your original question (one of them) was "How can the Dirac levels and delays influence bass management?"
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?
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Bass management on 2x4 question 1 month 2 weeks ago #28285

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AustinJerry wrote:
The original 88BM user guide in section 5.2 has the following instructions: "Bass management should be set up after Dirac Live calibration. This ensures that levels and delays are correct. Save your current configuration to a file before you begin to set up bass management. If, after setting up bass management, you wish to redo the Dirac Live calibration, reload this configuration file first. (This is because of a technical detail in the way that the DDRC-88BM processing interacts with the Dirac Live processing.)"

The current user guide states "Bass management should be set up after Dirac Live calibration. This ensures that levels and delays are correct."

This is unclear to me. My understanding is that the Dirac Live calibration results and the bass management configuration are entirely independent of one another. How can the Dirac levels and delays influence bass management?

And when the Dirac Live calibration is re-run, what configuration file should be reloaded first? And what is the interaction between Dirac Live and bass management?

Are the recommendations in the first quote no longer valid? My recommendation would be to re-word this section so its meaning is more clear.

Ok, let's try to dispel the mystery somehow... :-)
Sometimes forum/emails aren't the easiest way but i know that both of you are great gents. No hard feelings.. :-) I "think" that you potentially talking of different section of the wording and the problem is our team might have confused the whole story too :-).. nice!
So let us try to see how we can clarify and surely see how we can improve that wording. Sounds good?

a) Jerry is entirely correct that Dirac Live and Bass management are not related. Dirac Live sweeps happens right at the Dirac live block (i..e in the middle of the DSP structure). So when a sweep goes as the basis for building the Dirac Live filters, it will go through each speaker and "not" through say Speaker + SUB.
Everybody all clear on I'm sure? I don't think there is a confusion. :-)

b) "Bass management should be set up after Dirac Live calibration. This ensures that levels and delays are correct"
What the next stage of the wording of the user manual says is that when you run Dirac Live, (and generate filters), it's going to do its magic for delay + filters. Agree? These filters "will" indirectly affect the bass management. We're not talking of the first tab, but we're talking of the "blending of bass" to the speakers. (because Dirac might have delayed). That's what John is referring to now.
And that's why the wording, do the "bass management after running Dirac live". i.e. We're talking of the tuning of the LPF/HPF and slopes to make sure they blend well at the crossover point (knowing a unique Dirac Live filter was just generated). That's the tricky part where you optimize using REW by running the sweep this time through BM + Dirac Live + Crossover and that's the only time you see the "blending" of BASS + Speaker. Everytime you generate a Dirac live filter, you're potentially (not sure) going to have different delay values, different filter response. Your "BM" (LPF + HPF) may need some tuning to help on the blending for this new Dirac Live filter...

Does this make any sense?

Now in the "real" word... on 90% of AVR, you've got almost no choice for the BM on the filter type/slope and even cut off. It's all baked and assuming your speakers are going to play nice with these preset settings. With Dirac Live + advanced BM, it's indeed bringing a new level of flexibility (aka complexity and fun to monkey around!). How much you want to "tune" is up to everybody's taste... :-)

Hoping we didn't confuse further and our apologies to Jerry if our team indeed brought some confusion by saying that this wording was from an older version. We were not clear enough and were referring to the section "If, after setting up bass management, you wish to redo the Dirac Live calibration, reload this configuration file first. (This is because of a technical detail in the way that the DDRC-88BM processing interacts with the Dirac Live processing" which I believe doesn't need to be here. That's legacy and something to update since BM doesn't affect Dirac Live at all.

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Bass management on 2x4 question 1 month 2 weeks ago #28291

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Thank you for a well-worded response, which clears up any confusion I had when I created my original post. And my apology to John for my responses that showed some frustration with what seemed like a disconnect.
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