G3P Elevated BM & LFE Issue

[marcl]

Jul 21, 2021 17:11:13 GMT -5 JKCashin said:

I have a spectrum analyzer, well, actually a digital oscilloscope with ability to do FFT spectrum calculation. I could test the outputs as long as the XMC-2 uses a common ground referenced to mains input, i.e., as long as the chassis ground is electrically equivalent to output ground pin. Does anyone know if this is the case? If not I will need to get an isolator. Sigh.

Also does anyone know what is the peak output voltage of the XMC-2 on the XLRs WRT ground? I even have the ability to do up to 4 measurements at once!

That would be wonderful!  Measure 2.0, 2.1, 2.2, 2.3 see how it goes :-)

[ttocs]

This very simple plot exhibits the Elevated BM in a nutshell. It only shows LFE in Teal, one Small channel in Purple from 20-1000Hz, and the Left Sub Mono in Dark Purple playing the BM for this Small channel all by itself.

The assumption is that LFE= +10dB, so BM is at +4dB in this plot.
LFE has been very consistent in all of my tests so it's why I use it as the "baseline" from which to measure down.

[okjazz]

I would like to be counted among those experiencing the unnecessary bass boost since FW2.2. To mitigate my situation, I also used the level (set at -11 in my RMC-1L) of my subwoofer output as the baseline for the rest of all my speakers. Keep in mind, this is after manually dialing down to mid or minimum level the nob of my subs.

I love the bass but not that much to boil my blood with the amount of the low frequency energy output by my processor. I am glad that few people in this forum went through the pain of quantifying the BM misbehaviors through measurements and other means. Thank you, and I hope Emotiva has heard you and would address the issue in the upcoming firmware update.

[ttocs]

FW2.3, User EQ, 200Hz XO, one subwoofer, Large Fronts, 5.1.2.
This is the Center channel configured as Small, the BM is sent to the Large Fronts because the only subwoofer is setup as LFE.
The result is at least +9dB of BM. With FW2.1 it was still elevated due to summing of both Large Fronts, but not this much.

[ttocs]

Yes, Emotiva is communicating. 

[p4t]

Thank you ttocs for your time and efforts to do all these testings. How about if only center channel set as large? Cause, if remember correctly your system also set the center as large. Do this problem also happen when the center channel only set as large?

[ttocs]

Jul 22, 2021 13:44:52 GMT -5 p4t said:

Thank you ttocs for your time and efforts to do all these testings. How about if only center channel set as large? Cause, if remember correctly your system also set the center as large. Do this problem also happen when the center channel only set as large?

I’ll run that scenario tonight and post the result.

[JKCashin]

Jul 21, 2021 17:57:04 GMT -5 marcl said:

Jul 21, 2021 17:11:13 GMT -5 JKCashin said:

I have a spectrum analyzer, well, actually a digital oscilloscope with ability to do FFT spectrum calculation. I could test the outputs as long as the XMC-2 uses a common ground referenced to mains input, i.e., as long as the chassis ground is electrically equivalent to output ground pin. Does anyone know if this is the case? If not I will need to get an isolator. Sigh.

Also does anyone know what is the peak output voltage of the XMC-2 on the XLRs WRT ground? I even have the ability to do up to 4 measurements at once!

That would be wonderful!  Measure 2.0, 2.1, 2.2, 2.3 see how it goes :-)

OK I am willing to do it but will need answers to my above questions before I can proceed

[marcl]

Jul 22, 2021 16:23:02 GMT -5 JKCashin said:

Jul 21, 2021 17:57:04 GMT -5 marcl said:

That would be wonderful!  Measure 2.0, 2.1, 2.2, 2.3 see how it goes :-)

OK I am willing to do it but will need answers to my above questions before I can proceed

It's fine to do this, but since ttocs and I have measurements all the way back to before FW 1.10, in the same rooms with the same gear, and the bass boost appeared with 2.2 and persists with 2.3 ... then measuring at the output will not (IMHO) change the result.

[ttocs]

210722-01
FW2.3
User EQ
Center Channel Large, all others Small
Center Sub LFE so BM goes to the Large Center
No other subwoofer channels used
edit: The plot in this post is flawed, but I'm leaving it for context. See six posts below for a more coherent plot. The Center Speaker woofer needed to be phase inverted for better operation with the Large Fronts and Surround Left.
My Center Speaker has a small subwoofer as a woofer so it's not very good below 40Hz, but good enough for center channel duty. 

This plot compares using Large Fronts for BM vs Large Center.
The Green trace is the Center Channel Speaker with BM going to the Large Front Speakers.
The Red trace is the Surround Left speaker with BM going to the Large Center Speaker.


This was a good suggestion as it was one scenario I had not done. Thanks p4t .

[marcl]

Jul 22, 2021 17:53:04 GMT -5 ttocs said:

210722-01
FW2.3
User EQ
Center Channel Large, all others Small
Center Sub LFE so BM goes to the Large Center
No other subwoofer channels used

My Center Speaker has a small subwoofer as a woofer so it's not very good below 40Hz, but good enough for center channel duty. You can see that the strong bass is around 75Hz but I'm not counting that as the measuring point because I'm a generous soul. Placing the cursor at 46Hz would put the elevated bass at +4dB higher than the frequency peaks above the XO. If I used 70-80Hz range the elevation amount would be more like +6dB.

This plot compares using Large Fronts for BM vs Large Center.
The Green trace is the Center Channel Speaker with BM going to the Large Front Speakers.
The Red trace is the Surround Left speaker with BM going to the Large Center Speaker.
View Attachment

This was a good suggestion as it was one scenario I had not done. Thanks p4t .

Have you done LCR large to show that small surrounds would be +5 due to the 2.2 bug PLUS +6 from having THREE large speakers?

[ttocs]

Jul 22, 2021 18:01:49 GMT -5 marcl said:

Jul 22, 2021 17:53:04 GMT -5 ttocs said:

210722-01
FW2.3
User EQ
Center Channel Large, all others Small
Center Sub LFE so BM goes to the Large Center
No other subwoofer channels used

My Center Speaker has a small subwoofer as a woofer so it's not very good below 40Hz, but good enough for center channel duty. You can see that the strong bass is around 75Hz but I'm not counting that as the measuring point because I'm a generous soul. Placing the cursor at 46Hz would put the elevated bass at +4dB higher than the frequency peaks above the XO. If I used 70-80Hz range the elevation amount would be more like +6dB.

This plot compares using Large Fronts for BM vs Large Center.
The Green trace is the Center Channel Speaker with BM going to the Large Front Speakers.
The Red trace is the Surround Left speaker with BM going to the Large Center Speaker.
View Attachment

This was a good suggestion as it was one scenario I had not done. Thanks p4t .

Have you done LCR large to show that small surrounds would be +5 due to the 2.2 bug PLUS +6 from having THREE large speakers?

Wait, what? ?  
Just kidding. I'll do that now.
That's gonna be some big bass bloat!

[ttocs]

210722-01
FW2.3
User EQ
LCR Large, all others Small
Center Sub LFE so BM goes to the Large LCR
No other subwoofer channels used



edit: This is flawed due to negative summation of the Center Speaker. I'm leaving this for history and reference. I inverted the phase of the woofer so it would work better with the Large Fronts and Surround Left and posted the result a few posts below.

[marcl]

Jul 22, 2021 18:11:43 GMT -5 ttocs said:

Jul 22, 2021 18:01:49 GMT -5 marcl said:

Have you done LCR large to show that small surrounds would be +5 due to the 2.2 bug PLUS +6 from having THREE large speakers?

Wait, what? ?  
Just kidding. I'll do that now.
That's gonna be some big bass bloat!

Yes but it would validate my equation for how it SHOULD work:   IF (CSub=LFE and L/RSubs=None), OR IF L/C/R Subs=None, AND n is number of large speakers, then BM gain adjustment should be (n-1) x (-3)

[ttocs]

Jul 22, 2021 20:01:10 GMT -5 marcl said:

Jul 22, 2021 18:11:43 GMT -5 ttocs said:

Wait, what? ?  
Just kidding. I'll do that now.
That's gonna be some big bass bloat!

Yes but it would validate my equation for how it SHOULD work:   IF (CSub=LFE and L/RSubs=None), OR IF L/C/R Subs=None, AND n is number of large speakers, then BM gain adjustment should be (n-1) x (-3)

I'm re-doing the comparos due to negative summation from the Center Speaker. My Center Speaker uses a dedicated sub for the woofer. I had to raise the active XO I use for the Center Speaker so only the sub would be working, then I had to invert the phase so it would work better with the Large Fronts. It's always something.

Then, because I can't use the Center Speaker as the Small because I'm now using it as a Large, I am using the Surround Left, sooooo, instead of trying to compare one small speaker vs a different small speaker, I ran all the comparisons with the same Surround Left for consistency and will delete the previous images above so there's no confusion.

Next post in a few minutes.

[ttocs]

210722-03
FW2.3
User EQ
Green Trace=Large Fronts are the only speakers providing BM
Red Trace=Large Center is the only speaker providing BM
Blue Trace=Large Left/Center/Right speakers are providing BM
Surround Left Small channel is being measured



marcl I'm not sure what to make of this. It appears to me that all three are pretty close at about 50Hz. The little sub I use for the Center Speaker has that big peak at 57Hz that should be ignored, and below 40Hz it takes a dive and takes the summed bass for LCR combo with it, so the only reliable section I see is between 45-55Hz. With that said, it looks like all three traces are a good +12dB above the Small SL above the XO.

Unfortunately, I don't see a progression of 1 large speaker, 2 large speakers, 3 large speakers, all adding more bass as they go. 

edit: This can't be right. I thought I could run a quick test and change channel configurations and get away with a quick result, but I think I need more prep for this. So I'm going through and tweaking each channel being used for best results.

[JKCashin]

Jul 22, 2021 17:51:47 GMT -5 marcl said:

Jul 22, 2021 16:23:02 GMT -5 JKCashin said:

OK I am willing to do it but will need answers to my above questions before I can proceed

It's fine to do this, but since ttocs and I have measurements all the way back to before FW 1.10, in the same rooms with the same gear, and the bass boost appeared with 2.2 and persists with 2.3 ... then measuring at the output will not (IMHO) change the result.

While I agree with what you are saying, I am offering only because it eliminates the room, microphone, amplifier, etc. from the equation. It should therefore be a supporting data point.

[p4t]

Jul 22, 2021 17:53:04 GMT -5 ttocs said:

210722-01
FW2.3
User EQ
Center Channel Large, all others Small
Center Sub LFE so BM goes to the Large Center
No other subwoofer channels used
edit: The plot in this post is flawed, but I'm leaving it for context. See six posts below for a more coherent plot. The Center Speaker woofer needed to be phase inverted for better operation with the Large Fronts and Surround Left.
My Center Speaker has a small subwoofer as a woofer so it's not very good below 40Hz, but good enough for center channel duty. 

This plot compares using Large Fronts for BM vs Large Center.
The Green trace is the Center Channel Speaker with BM going to the Large Front Speakers.
The Red trace is the Surround Left speaker with BM going to the Large Center Speaker.
View Attachment

This was a good suggestion as it was one scenario I had not done. Thanks p4t .

You are welcome,ttocs. In fact, we are very appreciate what you did. I have a questions, if center channel set as large, and all other speakers set as small (including the fronts), left sub= mono, center sub= LFE, do the BM still goes to center channel? OR BM go to left sub? Also for your center channel case, how about change the center channel to small and set the crossover at 40Hz, since below 40Hz your dedicated center channel sub not working optimal. Do this solve at least for center channel problem?

[ttocs]

I decided to swap subs for the Center Speaker. I took the old Rel out and put in a ML Dynamo 800X, which is much easier to get a good result with. I also painstakingly tweaked the Left, Center, and Right speakers so they all play as flat and un-lumpy as possible while using the User EQ (I'm used to Dirac doing this work for me).

This new plot shows each Large speaker, Left, Center, and Right, as dotted lines. The Small Surround Left channel is shown as the solid lines. So here's one issue when mixing speakers together and playing the same mono bass together, there is negative summation. The Large Left/Center/Right channels playing BM together is lower in level than just the two Large Fronts. I believe this is because the Large Center speaker is pulling down, or summing in a negative way, the response when it plays with the Large Fronts.

So while it's proper to say that each additional large speaker which will provide BM for the Small channels should tell the Bass Management system to reduce the output by -3dB per each additional speaker, this will require the user to verify that every large speaker will work together with the group, just like we do with subwoofers.

Meanwhile, the single Large Center Speaker is at +9dB of elevated BM, and the Large Fronts are at close to +15dB.

All this gobble-dee-guk is to say that I think marcl is correct. But, the main correction still needs to be figured out, namely that with just one Large speaker the BM is at +9dB, why? The Center Sub is set for LFE and I verified it isn't playing while measuring the Small channels.

[ttocs]

Jul 22, 2021 22:50:04 GMT -5 p4t said:

You are welcome,ttocs. In fact, we are very appreciate what you did. I have a questions, if center channel set as large, and all other speakers set as small (including the fronts), left sub= mono, center sub= LFE, do the BM still goes to center channel? OR BM go to left sub?

Also for your center channel case, how about change the center channel to small and set the crossover at 40Hz, since below 40Hz your dedicated center channel sub not working optimal. Do this solve at least for center channel problem?

The BM will go only to subwoofers whenever any sub is setup as some form of Mono, and not a Large Speaker channel.

As for the second question, no. It's an old, small Rel and is limited in what can be done to tweak it. I've been thinking of replacing it with what I used tonight for the testing, so I guess I'll be getting another one based on the results tonight.