Dirac and REL subs

[richter250]

So I am the proud owner of a new pair of REL S/812 subs. They are connected via their high level inputs to the same amp as my Maggie 3.7is. REL strongly recommends disconnecting the subs before running room correction software and then balancing the subs afterward. I guess because I am a Dirac fanboy this just didn’t seem right to me. So I balanced the subs with the mains as well as possible with no correction and then ran Dirac with the subs connected. I am getting really good results confirmed with REW and my ears. Anyone else have any experience with this?

REL usually mentions Audessy when making this recommendation and they say having the subs connected during room correction will result in the program measuring too much bass and then sucking all the bass out after correction. I have not found this to be the case in my set up.

[marcl]

Jun 27, 2022 9:14:54 GMT -5 richter250 said:

So I am the proud owner of a new pair of REL S/812 subs. They are connected via their high level inputs to my Maggie 3.7is. REL strongly recommends disconnecting the subs before running room correction software and then balancing the subs afterward. I guess because I am a Dirac fanboy this just didn’t seem right to me. So I balanced the subs with the mains as well as possible with no correction and then ran Dirac with the subs connected. I am getting really good results confirmed with REW and my ears. Anyone else have any experience with this?

REL usually mentions Audessy when making this recommendation and they say having the subs connected during room correction will result in the program measuring too much bass and then sucking all the bass out after correction. I have not found this to be the case in my set up.

I split my L/R to a miniDSP so I can run summed L+R to the subs ... and have Dirac see the fronts across the full range.  It sees the summed response of the subs and the front speakers across the crossover point and ensures a flat transition.  It works.  What you're doing should work fine.  

But of course I would encourage measuring the actual response after correction to be sure.  If you want more bass, you can take that smooth flat response and tip the target curve up a bit.  You have control.

[richter250]

Thanks Marci! Still tweaking and breaking in the subs. Measuring really well right now. Just a slight dip around 40hz which I suspect is right around the crossover point.

[KeithL]

That sounds like the right way to do it to me as well.

I suspect that their issue is that it would be bad if you had the subs connected but NOT balanced well with the main speakers.
You would then be forcing the room correction to try to correct the imbalance between them.
And I can see all sorts of reasons why that might not work out very well.
You would be trying to to make a single correction to cover multiple physical speakers at multiple locations.
(So you could quite well end up with some very odd results.)

Alternately, assuming you run the room correction with both the speaker and the sub...
Then you CANNOT really adjust the level of the sub later without undoing what the room correction did...
And they seem to sort of value your ability to "tweak the sub to taste" as the last step in the process.

It has been my experience that, with the high-level connection, REL has always looked at the process as:
Set everything up just right without the subs... then add the subs to fill in the gaps later... adjusting them to taste.
(Sort of the opposite of actively managing how the subs interact with your other speakers.)
(The analogy may seem odd... but sort of like the way you use wood filler to fill in low spots and broken corners.)
(Note that this will end up ensuring that the audible contribution of the sub is absolutely minimized EXCEPT where there are gaps that need filling.)

Jun 27, 2022 9:29:48 GMT -5 marcl said:

Jun 27, 2022 9:14:54 GMT -5 richter250 said:

So I am the proud owner of a new pair of REL S/812 subs. They are connected via their high level inputs to my Maggie 3.7is. REL strongly recommends disconnecting the subs before running room correction software and then balancing the subs afterward. I guess because I am a Dirac fanboy this just didn’t seem right to me. So I balanced the subs with the mains as well as possible with no correction and then ran Dirac with the subs connected. I am getting really good results confirmed with REW and my ears. Anyone else have any experience with this?

REL usually mentions Audessy when making this recommendation and they say having the subs connected during room correction will result in the program measuring too much bass and then sucking all the bass out after correction. I have not found this to be the case in my set up.

I split my L/R to a miniDSP so I can run summed L+R to the subs ... and have Dirac see the fronts across the full range.  It sees the summed response of the subs and the front speakers across the crossover point and ensures a flat transition.  It works.  What you're doing should work fine.  

But of course I would encourage measuring the actual response after correction to be sure.  If you want more bass, you can take that smooth flat response and tip the target curve up a bit.  You have control.

[ttocs]

Jun 27, 2022 9:14:54 GMT -5 richter250 said:

So I am the proud owner of a new pair of REL S/812 subs. They are connected via their high level inputs to the same amp as my Maggie 3.7is. REL strongly recommends disconnecting the subs before running room correction software and then balancing the subs afterward. I guess because I am a Dirac fanboy this just didn’t seem right to me. So I balanced the subs with the mains as well as possible with no correction and then ran Dirac with the subs connected. I am getting really good results confirmed with REW and my ears. Anyone else have any experience with this?

REL usually mentions Audessy when making this recommendation and they say having the subs connected during room correction will result in the program measuring too much bass and then sucking all the bass out after correction. I have not found this to be the case in my set up.

I've had mine connected like yours for a couple years and run Dirac with no issue. If you're getting good results and you're happy, that's all that matters.

[marcl]

Jun 27, 2022 10:00:40 GMT -5 richter250 said:

Thanks Marci! Still tweaking and breaking in the subs. Measuring really well right now. Just a slight dip around 40hz which I suspect is right around the crossover point.

You might want to push the crossover up 10Hz.  I let my 3.7 (not "i") fronts run full range which takes them down below 40Hz easily due to a huge room resonance at 40.  So I don't high pass filter them because the way I'm doing it there's no easy way to do that ... i.e. I don't want to run the signal for the 3.7s through the miniDSP.  In the miniDSP I experimented with crossovers for the subs and found the best result with a high pass at 10Hz and low pass at 50Hz.  This gives the most uniform response without Dirac.  I can also tweak the sub level this way.  So it does make sense to get the best response without Dirac and then let Dirac optimize the response from there.

And then there's this other point I need to make ... best response would be to use the two subs in mono and place them center of the front and rear walls and run L+R to both subs.  

[richter250]

]
And then there's this other point I need to make ... best response would be to use the two subs in mono and place them center of the front and rear walls and run L+R to both subs.   [/quote]


Why not run the subs in stereo thus preserving the possible spatial cues present in the low bass as recommended by Jim Smith in Get Better Sound.

[marcl]

Jun 27, 2022 11:56:14 GMT -5 richter250 said:

]
And then there's this other point I need to make ... best response would be to use the two subs in mono and place them center of the front and rear walls and run L+R to both subs.  

Why not run the subs in stereo thus preserving the possible spatial cues present in the low bass as recommended by Jim Smith in Get Better Sound.
[/quote]

I don't think there's any scientific basis for being able to locate bass below 40Hz.  Meanwhile, the benefit to more uniform bass response in the room and cancellation of some modal resonances is well documented.  Toole, Welti, etc.

[richter250]

Is there a deeper wormhole in all of Audio than integrating subs into a system? 😂😂

[ttocs]

Jun 27, 2022 12:04:55 GMT -5 richter250 said:

Is there a deeper wormhole in all of Audio than integrating subs into a system? 😂😂

Well, there are quite a few ways to setup subs. And possibly many reasons to go along with each setup type.

[marcl]

Jun 27, 2022 14:07:29 GMT -5 ttocs said:

Jun 27, 2022 12:04:55 GMT -5 richter250 said:

Is there a deeper wormhole in all of Audio than integrating subs into a system? 😂😂

Well, there are quite a few ways to setup subs. And possibly many reasons to go along with each setup type.

And as with everything in audio (and life in general, it seems, these days) there are things people say and swear to that defy physics and biology.  

[KeithL]

There are some very good arguments in BOTH directions.
(And the wormhole, or perhaps rabbit hole is a better description, has many different branches too.    )

In favor of stereo subs:
- We aren't supposed to be able to pick out spatial cues below 80-100 Hz but maybe sometimes we can.
- No crossover is perfectly sharp so the subs will have SOME output even several octaves above the crossover point.
- Maybe we should count extraneous mechanical cues (if the wall rattles on the left, and not the right, does that count as a spatial cue or not?).

Against stereo subs:
- The LFE channel on discs and streams is mono so there is no stereo information there anyway.
- If you happen to listen to vinyl there is also virtually no stereo information there either at low frequencies
   (the low bass on vinyl, if there is any, is mixed to mono to avoid groove symmetry that would be too hard for a cartridge to track).
- This assumption precludes positioning the subs wherever in the room they make the best low bass
   (there are many reasons why multiple subs may work best when arranged asymmetrically - for example one in a corner and one in a center-wall)
   (there are also many reasons why sitting the subs symmetrically next to each speaker may NOT work well in a particular room either).
- Obviously, unless you have two identical subs, they aren't going to be symmetrically matched no matter what you do.

In favor of a high-level connection (like Rel recommends):
- It should work equally well with all content - including pure stereo content.
- It forces you to allow your main speakers to cover their full range and use the sub or subs only for "fill".

In favor of a separate bass-managed connection:
- Bass management gives you a real crossover - and so minimizes the low bass your main speakers and amp channels need to handle.
- ON a more general note this minimizes the overlap between the subs and main speakers.
   (REL is convinced that you'll get a smoother blending between subs and mains with more overlap but this may not always be the case.)
- Most home theater gear EXPECTS it to be done this way (so it's easier to set up).
- Will work with all preamps and amplifiers
   (the high-level inputs on SOME subwoofers may use a common ground - which may not work with most BALANCED amplifies - like our XPA-DR's)
   (SOME speakers are OK with this; I believe at least some RELs have a different input and cable for doing the high-level connection with a balanced amp).

In favor of doing one OR the other and NOT both:
- Potential ground noise issues or other interactions.
- Settings on the sub that work best with one type of connection may NOT work well with the other.

Do remember that Dolby Atmos home CONTENT only has one mono LFE channel...
(And, assuming that they use the LFE channel properly, there shouldn't be massive amounts of "sub-bass" in the main channels of movies.)

Jun 27, 2022 11:56:14 GMT -5 richter250 said:

]
And then there's this other point I need to make ... best response would be to use the two subs in mono and place them center of the front and rear walls and run L+R to both subs.  

Why not run the subs in stereo thus preserving the possible spatial cues present in the low bass as recommended by Jim Smith in Get Better Sound.
[/quote]

[marcl]

Jun 27, 2022 15:35:41 GMT -5 KeithL said:

There are some very good arguments in BOTH directions.
(And the wormhole, or perhaps rabbit hole is a better description, has many different branches too.    )

In favor of stereo subs:
- We aren't supposed to be able to pick out spatial cues below 80-100 Hz but maybe sometimes we can.
- No crossover is perfectly sharp so the subs will have SOME output even several octaves above the crossover point.
- Maybe we should count extraneous mechanical cues (if the wall rattles on the left, and not the right, does that count as a spatial cue or not?).

Against stereo subs:
- The LFE channel on discs and streams is mono so there is no stereo information there anyway.
- If you happen to listen to vinyl there is also virtually no stereo information there either at low frequencies
   (the low bass on vinyl, if there is any, is mixed to mono to avoid groove symmetry that would be too hard for a cartridge to track).
- This assumption precludes positioning the subs wherever in the room they make the best low bass
   (there are many reasons why multiple subs may work best when arranged asymmetrically - for example one in a corner and one in a center-wall)
   (there are also many reasons why sitting the subs symmetrically next to each speaker may NOT work well in a particular room either).
- Obviously, unless you have two identical subs, they aren't going to be symmetrically matched no matter what you do.

In favor of a high-level connection (like Rel recommends):
- It should work equally well with all content - including pure stereo content.
- It forces you to allow your main speakers to cover their full range and use the sub or subs only for "fill".

In favor of a separate bass-managed connection:
- Bass management gives you a real crossover - and so minimizes the low bass your main speakers and amp channels need to handle.
- ON a more general note this minimizes the overlap between the subs and main speakers.
   (REL is convinced that you'll get a smoother blending between subs and mains with more overlap but this may not always be the case.)
- Most home theater gear EXPECTS it to be done this way (so it's easier to set up).
- Will work with all preamps and amplifiers
   (the high-level inputs on SOME subwoofers may use a common ground - which may not work with most BALANCED amplifies - like our XPA-DR's)
   (SOME speakers are OK with this; I believe at least some RELs have a different input and cable for doing the high-level connection with a balanced amp).

In favor of doing one OR the other and NOT both:
- Potential ground noise issues or other interactions.
- Settings on the sub that work best with one type of connection may NOT work well with the other.

Do remember that Dolby Atmos home CONTENT only has one mono LFE channel...
(And, assuming that they use the LFE channel properly, there shouldn't be massive amounts of "sub-bass" in the main channels of movies.)

Jun 27, 2022 11:56:14 GMT -5 richter250 said:

]
And then there's this other point I need to make ... best response would be to use the two subs in mono and place them center of the front and rear walls and run L+R to both subs.  

Why not run the subs in stereo thus preserving the possible spatial cues present in the low bass as recommended by Jim Smith in Get Better Sound.

Briefly 

• Yes, mastering guidelines for vinyl have always said:  sum to mono below 200Hz,  roll off below 30Hz and above 16KHz
• Unless you run L/R direct to two subs, there is no "stereo" in the sub outputs or from bass management with our processors
• My comments to the OP were specific to pairing Maggie 3.7 to subs, with which I have  lots of experience trying lots of methods.  But that speaker does great down to 40Hz, so that's what we're talking about ... the bottom octave.
• I'll repeat ... lots of people have tried lots of stuff and have opinions and perceptions, but Welti modeled and tested it.  

So yeah if we broaden the argument to include all fringe cases we could have a huge room where a sub placed 10-15ft off center could make that side of the room sound heavy ... or a crossover at 80Hz to subs that don't play as well at 80Hz as the mains .... etc.  But in real rooms with dimensions under 30ft, all the benefits of Welti's recommendations outweigh any perceived gains of "stereo" below 80Hz. 

[richter250]

Thanks guys! So many options to consider! One of the great things about the Emotiva processors is the multiple Dirac presets. This lets me try multiple options at once. Right now I have one preset for stereo music. This preset uses only the high level inputs in the RELs and no sub output from the RMC-1 and I can evaluate the wonder of stereo subs. The second is for movies and uses the LFE input in the REL with the mains crossed over at 80hz in the processor. This keeps the crazy sub bass effects from movies out of my Maggie’s and I get the joy of two mono subs. Now, sub placement to optimize both? That’s opening a new can of worms. Or Rabbits. So much fun trying different things. Thanks for all the advice!

[marcl]

Jun 27, 2022 17:58:22 GMT -5 richter250 said:

Thanks guys! So many options to consider! One of the great things about the Emotiva processors is the multiple Dirac presets. This lets me try multiple options at once. Right now I have one preset for stereo music. This preset uses only the high level inputs in the RELs and no sub output from the RMC-1 and I can evaluate the wonder of stereo subs. The second is for movies and uses the LFE input in the REL with the mains crossed over at 80hz in the processor. This keeps the crazy sub bass effects from movies out of my Maggie’s and I get the joy of two mono subs. Now, sub placement to optimize both? That’s opening a new can of worms. Or Rabbits. So much fun trying different things. Thanks for all the advice!

You're on the right track!   So let me ask this .... can you connect the L/R to the RELs the way you do, and ALSO run Center Sub output from the RMC-1 to the RELs' LFE inputs (Y cable)?  If you can do this, then set the Center Sub=LFE and Fronts to Large.  For stereo, you use Preset 1 with Center Sub=None.  For movies, you use Preset 2 with Center Sub=LFE, Fronts set to Large.

I can't remember, is this also a multichannel system with small speakers?  If so, the Preset 2 for movies will send small speaker bass to the 3.7i and the RELs below the crossover ... but the high dynamics LFE will ONLY go to the RELs.

[richter250]

Thanks Marci! That is almost exactly how I have things set up. I do have smaller speakers for the other surround channels. I have the center sub output going the LFE input on both RELs. They can be daisy chained. I tried the exact configuration that you mention with the fronts set as large and the surrounds as small and center sub set as LFE in Preset 2 for movies. However, the Maggies were slapping (or whatever you call it, not a good sound!) during loud explosions and such. We listen to movies loud. 😎. The Maggies were obviously getting too much bass. So I switched the center sub to mono and crossed over the Maggies randomly to 80 Hz. I rarely listen to music in multichannel so this seemed like a good compromise?

[marcl]

Jun 28, 2022 7:32:33 GMT -5 richter250 said:

Thanks Marci! That is almost exactly how I have things set up. I do have smaller speakers for the other surround channels. I have the center sub output going the LFE input on both RELs. They can be daisy chained. I tried the exact configuration that you mention with the fronts set as large and the surrounds as small and center sub set as LFE in Preset 2 for movies. However, the Maggies were slapping (or whatever you call it, not a good sound!) during loud explosions and such. We listen to movies loud. 😎. The Maggies were obviously getting too much bass. So I switched the center sub to mono and crossed over the Maggies randomly to 80 Hz. I rarely listen to music in multichannel so this seemed like a good compromise?

I know that sound!  Terrifying, isn't it ... the DWM does it too.  But I'm surprised you're having this problem.  I have the 3.7 set as large and the subs add the bottom octave but the 3.7 still gets full range.  LFE goes only to the subs and not the 3.7.  I've never had the slap issue when watching movies.  And overall I like the sound sending small speaker bass to the 3.7 instead of the subs, especially because my smalls cross at 90-110Hz.

I wonder if somehow LFE is getting to your 3.7i .... or maybe I just don't listen as loud.

But if you're going to set the Maggies to small for movies and cross them over, I would think 50Hz would sounds better and not have a slap issue.   I used 50Hz when I had mine set to small, as 60Hz sounded a bit bloated and 40Hz didn't integrate well in the transition.  BTW, I tracked down the most offensive slap frequency to be 26Hz.

[richter250]

It would be just fine if I never heard that sound again!😂 The movie “Black Widow” was the culprit. I don’t think the LFE channel was getting to the 3.7is. As long as a sub is connected at any setting that shouldn’t happen. Right? I will definitely try dialing the crossover down to 50Hz. Thanks for your help!

[ttocs]

Jun 28, 2022 8:58:43 GMT -5 richter250 said:

It would be just fine if I never heard that sound again!😂 The movie “Black Widow” was the culprit. I don’t think the LFE channel was getting to the 3.7is. As long as a sub is connected at any setting that shouldn’t happen. Right? I will definitely try dialing the crossover down to 50Hz. Thanks for your help!

I wanted to find out how low the frequencies could get in the Center channel. Straight Outta Compton happened to be playing repeatedly that week, so it was an easy choice, and it had 28Hz bass in the Center channel. This wasn't LFE.

So while Dolby may spec a low frequency of 40Hz for the "Screen Speakers", movies are often mixed with lower content in these non-subwoofer channels.

[marcl]

Jun 28, 2022 8:58:43 GMT -5 richter250 said:

It would be just fine if I never heard that sound again!😂 The movie “Black Widow” was the culprit. I don’t think the LFE channel was getting to the 3.7is. As long as a sub is connected at any setting that shouldn’t happen. Right? I will definitely try dialing the crossover down to 50Hz. Thanks for your help!

If the fronts are set to large, and all the sub outputs set to none, then LFE goes to the fronts.  But it seems you don't do that for watching movies.  Still a mystery.  But like ttocs says, some movies do have content down to 30 or below in the non-LFE channels.

As for sub placement ... it's generally never the case that the right place for fronts is anywhere near the right place for subs ... unless you put both 25% from the front and side walls, which could work well.  But even then, you don't get the benefit of mode cancellation from subs playing from opposite ends of the room.  That cancellation gives you fewer peaks and nulls, and more uniform bass response across listening positions.  Here's the Welti work on the subject ...

www.harman.com/documents/multsubs_0.pdf