[vondy]

I’ve posted on a Dirac forum for enlightenment on my issue here. Not sure I’m really getting answers so maybe the folks who actually own these speakers will have more insight.

I know most here are mainly concerned with 2ch, as am I, but I also know a few of you are in to HT.

Currently I’m running a 5.0.2 setup. M3s for mains, Klipsch Academy for Center and RSL speakers for surrounds and atmos. No subs as you can see.

Amp is a NAD T-778 which is their flagship HT amp. It also works very well with music as their whole deal is audio quality above all else. Dirac is built in for processing.

I would not mind having subs but space is at a premium in our living room. The M3s sound so good with movies and shake the room when needed so I really haven’t missed subs.

Recently we have been going through all the Marvel movies with our girls for movie nights. Watching via Disney Plus. Seems like at least once in every movie there is a LFE that scares the crap out of us because of this awful noise. At first I thought it was were surrounds being pushed too hard. Last weekend I investigated and to my surprise found it to be my M3s!

I would keep playing the same scene, with my hand on the volume nob, and would watch my top woofer start to dance all over the place and make this crackly noise.

My first thought is the amp should NOT be sending LFE to a full range speaker. It knows I have no sub attached. Dirac has measured the speaker in my room so it also knows its capabilities.

Then there are those measurements, Dirac shows nothing really happening until almost 60Hz. I’ll attached a pic. If I move my Dirac curtains to 50Hz the problem pretty much goes away. Obviously I need to work on positioning in my room.

Still this whole thing seems odd to me. I’m new to the Dirac stuff and frequency responses. I have REW downloaded and may work on some positioning this weekend but I don’t see why that would keep my driving from bottoming out.

Any thoughts?

[Mr. Big]

Something is amiss. To bottom out these subs would take ear-bleeding levels. They are being fed a signal from your system that is causing this. My preamp I can change gain levels, 12Db is ideal, but if I go to 16Db of gain , woofers will produce noise (distortion). I go back to 12Db of gain and all is well. My preamp was over driving my amp thus causing the issue.

[Bingenito]

The image is not large enough for me to see what is going on and you do not have a link to your gallery where it is posted. I am not a pre/pro expert however

1- If you do not have a sub and the main speakers are set to full range or large they will play the full signal being fed
2- The graph looks as if Dirac may be applying room correction below 50hz.
3- The combination of using EQ boast below 50hz + sending a full range signal to a speaker with a movie soundtrack that can easily have 10hz bass frequencies will certainly cause the woofer (its not a subwoofer) to reach it's xmax. That is what you are hearing and this is not specific to a Spatial speaker but any speaker where you artificially boast the low end and then feed it a signal well beyond what that speaker can produce.

If you want to continue to use EQ on the bottom end for music you can try setting the M3 to Small in the processor and cut them off at 40hz 12-24db per octave. That should create a natural roll off and give you plenty for music but not cause driver excursion issues with movies.

Hope that helps.

[vondy]

Thanks for the responses!

I'm attaching a closeup of the curve here. Only the items to the right of the vertical green curtain is what Dirac is adjusting. To my eyes, it's only concerned with about 32Hz and above. So I would think no sub frequencies would be going to the mains. The amp knows I don't have a sub so it should not send sub frequencies to a full range speaker, at least that's my understanding. I'll need to dig into it more.

Keep in mind this is a Dirac measurement using a wide range of locations around my listening area.

This just occurred to me, say the speaker is hitting 32Hz somewhere else in the room but only measures close to 50Hz at my listening position. Is Dirac pushing it to 32Hz at my listening position causing the speaker to actually be pushed beyond their limits? This is totally an uneducated guess.

[Mr. Big]

Thanks for the responses!

I'm attaching a closeup of the curve here. Only the items to the right of the vertical green curtain is what Dirac is adjusting. To my eyes, it's only concerned with about 32Hz and above. So I would think no sub frequencies would be going to the mains. The amp knows I don't have a sub so it should not send sub frequencies to a full range speaker, at least that's my understanding. I'll need to dig into it more.

Keep in mind this is a Dirac measurement using a wide range of locations around my listening area.

This just occurred to me, say the speaker is hitting 32Hz somewhere else in the room but only measures close to 50Hz at my listening position. Is Dirac pushing it to 32Hz at my listening position causing the speaker to actually be pushed beyond their limits? This is totally an uneducated guess.

Take Dirac correction out of the system and play movies el-natural and see if the woofers are clipping, if not you got your answer. Use these types of corrections with care, you are multiplating the signal.

[Bingenito]

Dirac is certainly the issue. These room correction applications are not all knowing and solving as some think that they are. You are adding 6db of gain which is like 4x the power to frequencies where xmax is exponentially higher than say 60 or 80hz.

Try what I called out above and set a filter to roll off the bottom octave… the crossover is a slope not a vertical line, not even close to a vertical line or remove the 6db boast.

[Tyson]

Only ever cut bass signals with EQ.  Never, ever, ever, ever boost them.  That is asking for trouble.

[WGH]

Seems like at least once in every movie there is a LFE that scares the crap out of us because of this awful noise. At first I thought it was were surrounds being pushed too hard. Last weekend I investigated and to my surprise found it to be my M3s!

Without a sub this is normal and expected behavior. I think you will find out that because you don't have a sub all the LFE is sent to the main speakers. Dirac is measuring low frequency response at the calibration volume, probably around 75 dB. But you are listening to movies at a much higher volume.

The latest movies bump up super low bass way above average listening level. The M3 go down to 30Hz, current movies have strong bass at 20-25 Hz, the results is the M3's bottom out.

Look at the low frequency chart below for Blade Runner 2049 (now on Netflix). My REL sub goes down to 18 Hz and until I fined tuned the Anthem ARC Genisis bass curve my sub would bottom out. Current films like Dune have similar low bass but the mix doesn't have the strong 15 Hz and huge 35 Hz bump, I guess the sound guys have learned from their mistakes. I can play Dune a lot louder than Blade Runner 2049 without bottoming out the sub.




Lowering the overall volume or just the sub's volume will decrease your overall enjoyment. Hopefully you have the ability to fine tune Dirac to adjust the Low Frequency Extension, Slope, and Minimum Correction Frequency.

Anthem Subwoofer Adjustments


Subwoofers that are fast enough to keep up with Spatial speakers and do home theater don't come cheap. Not all subs can go down to 20 Hz at full power that is needed for movie soundtracks. The REL Carbon Special is one of them.

[vondy]

Great points everyone!

Something I'm trying to understand is...

The speaker's crossover should not allow frequencies below 32Hz to be sent to the driver. So what's going on? Is it the SPL levels are being boosted for those effects? I don't have the volume turned up that loud, it's even hard to hear some of the dialog. We probably listen around -20 and most of the movie sounds great. When testing this bottoming out, it would happen even at -30.


I have started looking into Subs. Been studying up on the GR Servo OB subs.

[Tyson]

Great points everyone!

Something I'm trying to understand is...

The speaker's crossover should not allow frequencies below 32Hz to be sent to the driver. So what's going on? Is it the SPL levels are being boosted for those effects? I don't have the volume turned up that loud, it's even hard to hear some of the dialog. We probably listen around -20 and most of the movie sounds great. When testing this bottoming out, it would happen even at -30.


I have started looking into Subs. Been studying up on the GR Servo OB subs.

The bolded part is almost certainly not true. 

OB subs are great for music, and also great for a combo HT/Music system.  But for pure HT I'd do a sealed sub, or 2.  Remember, sealed subs can be tucked away in a corner, while OB subs must be 3 feet from the walls to sound best, so visually they take up a lot of space in a typical room. 

[WGH]

Is it the SPL levels are being boosted for those effects?

Oh yea! That's the fun part. Looking at the Blade Runner chart: all the low frequencies above 60 Hz are above your -20 dB listening level with the 35 Hz peak above the 0 dB Dolby reference level. I haven't watched the Netflix stream to see if they filtered out that boost so it would play on an average HT or sound bar.

As an example, the REL Carbon Special has a 4”(100mm) of fore-and-aft stroke, can the Spatial woofers do that? In your setup they are trying to and failing.

[vondy]

The bolded part is almost certainly not true. 

OB subs are great for music, and also great for a combo HT/Music system.  But for pure HT I'd do a sealed sub, or 2.  Remember, sealed subs can be tucked away in a corner, while OB subs must be 3 feet from the walls to sound best, so visually they take up a lot of space in a typical room.

Interesting. I just read this short article from PS Audio about setting all speakers to full range because the crossovers limit what will be sent to the drivers. This is what made me think it was more of a SPL thing.

https://www.psaudio.com/pauls-posts/full-range/

I will say that I have never had this issue with any other speaker setup. I've never used this particular amp with anything other than the Spatials though.

What would be a suggested sub/subs if not open baffle? GRs sealed servos? My hope would be to incorporate the subs into my 2ch listening as well but I guess it would not be mandatory.

I tried out an SVS sub with another HT system I was experimenting with. Trying to separate HT from 2ch. Turns out I preferred the M3s for movies over it. The sub was deeper but the M3s gave more of that chest pounding effect that felt more real to me. They can really shake the room with movies. Perhaps a properly incorporated sub would be even better.

I'd also like to ask, looking at the closeup of my response. The thin blue and yellow lines are the M3s actual measurements. Is that small hump around 32Hz actually anything or are we not seeing any real low end till around 50hz? I'm still trying to understand these graphs.

[Tyson]

Interesting. I just read this short article from PS Audio about setting all speakers to full range because the crossovers limit what will be sent to the drivers. This is what made me think it was more of a SPL thing.

https://www.psaudio.com/pauls-posts/full-range/

I will say that I have never had this issue with any other speaker setup. I've never used this particular amp with anything other than the Spatials though.

What would be a suggested sub/subs if not open baffle? GRs sealed servos? My hope would be to incorporate the subs into my 2ch listening as well but I guess it would not be mandatory.

I tried out an SVS sub with another HT system I was experimenting with. Trying to separate HT from 2ch. Turns out I preferred the M3s for movies over it. The sub was deeper but the M3s gave more of that chest pounding effect that felt more real to me. They can really shake the room with movies. Perhaps a properly incorporated sub would be even better.

I'd also like to ask, looking at the closeup of my response. The thin blue and yellow lines are the M3s actual measurements. Is that small hump around 32Hz actually anything or are we not seeing any real low end till around 50hz? I'm still trying to understand these graphs.

Paul is wrong.  You should not set speakers to full range as none of them are going to be able to handle a full range HT signal without running into trouble.

Re: your graphs, it looks to me like there's before and after.  The really lumpy lines are before and the very smooth lines are after.  You can see in the before line that you're not getting much bass below 50hz in your room with those speakers.  So yes, IMO you need some subs, even for music.  If it were me, I'd get a pair of OB subs for music, and a sealed sub or 2 for the HT LFE channel.

[vondy]

Paul is wrong.  You should not set speakers to full range as none of them are going to be able to handle a full range HT signal without running into trouble.

Re: your graphs, it looks to me like there's before and after.  The really lumpy lines are before and the very smooth lines are after.  You can see in the before line that you're not getting much bass below 50hz in your room with those speakers.  So yes, IMO you need some subs, even for music.  If it were me, I'd get a pair of OB subs for music, and a sealed sub or 2 for the HT LFE channel.

Thanks! The thin lines are the measurements and the thick ones the Dirac corrected. The solid green is the target curve.

The main reason I don't have subs now is a lack of space. So a few for HT and 2ch ain't going to happen. 

I am going to get REW going and see what I might can do with some placement this weekend. Would like to get the most out of the 3Ms as possible.

[WGH]

Generally, in a setup without a sub, bass below the center and surround speakers' highpass-filter frequency, along with the LFE channel, is fed to the front speakers.

Music systems with and without a sub are set up for a flat frequency response. Home theater is a different animal.

In home theater, the LFE channel fixed offset is +10 dB above the main listening level, this gives soundtracks the necessary oomph for all those special effects we love.




You will have to contact NAD tech support to find out what happens to the LFE level when there is no sub and front speakers are set to large. Is the LFE level attenuated or is that fixed +10 dB sent to your main speakers causing them to bottom out? You won't always be around to gain ride the volume when the girls are watching.

[Bingenito]

My initial 2 responses explain why it happens. Tyson is exactly right never boast with EQ, only ever attenuate. Do that and your problems are gone.

2 subs are the solve if you can fit them later. Sell furniture:)

[studiotech]

Adding to what's already been said.  Setting an AVR to NO LFE routes ALL bass content to your main speakers.  Large, powerful main speakers may handle this well, but NOT open baffle, no matter how capable they may sound on music.  Bass content mixed in blockbuster films is orders of magnitude more powerful than in most any music.  Add in Dirac trying to force more bass output with massive EQ and you're destined to keep bottoming out the woofer cone.

Even relatively small subwoofers with several 8-10 drivers of good quality can produce significantly more bass output than most 12-15" open baffle speakers.

I'd vote for a pair of sealed Rythmik subs for both music and HT duties.  If you've got the Spatials out from the front wall like you should, the subs can be placed directly behind them.

Greg

[Bingenito]

Always a good day when some dude named StudioTech validates what you said.