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How Much Subwoofer Is Enough?

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mj30250

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Well, seems you have hit your bass Nirvana - which is great. Don't think that you can do much more on that front. While more subs will always tend to add a bit more, you don't really seem to need it either in frequency response or SPL. Decay time is a different matter, but as long as it sounds reasonably tight, would not really bother.

Perhaps time to upgrade the bed channels to full towers and try how that works? Also, did you thing of the upcoming Dirac ART?
Agreed, I'm good. Perhaps at some future point I'll add a couple nearfield subs, more for additional tactile response / envelopment than anything, but that would likely be frivolous and then there are the additional challenges that this introduces to the integration process.

I do use towers left and right and a big 3-way center. The plots above are subs-only. They keep up quite well when the volume gets pushed. I tend to get good results from Audyssey (when used with the companion app), so I've not given much thought to Dirac.
 

wwenze

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Kylo-Ren-More-2-meme-9.jpg
 

Oddball

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Agreed, I'm good. Perhaps at some future point I'll add a couple nearfield subs, more for additional tactile response / envelopment than anything, but that would likely be frivolous and then there are the additional challenges that this introduces to the integration process.

I do use towers left and right and a big 3-way center. The plots above are subs-only. They keep up quite well when the volume gets pushed. I tend to get good results from Audyssey (when used with the companion app), so I've not given much thought to Dirac.
Don't think it would be frivolous to go for more, but good to set a direction of travel.

Are you using the Audyssey/D&M LFE+Main setting for your LCR or even perhaps LFE distribution? These are potentially enhancements you could get for fee.
 

Fredygump

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Below are compression sweeps that I ran when the Monolith 15s were in use. The mic was positioned at the MLP, which is about 11ft distant from the subs.

compression-png.3600438


This is a nice amount of headroom and perhaps enough for my needs. I still had to satisfy my curiosity, though. With the PSAs, I'm finding more qualitative differences than quantitative ones. What's most telling is that with the Monoliths tuned hot for loud movie watching, I'd often feel it necessary to reduce the sub signal when switching to music, as bass could become intrusive and overpowering. With the PSAs, I haven't felt the need to do that. It's almost like going from good speakers to great ones - great speakers often don't sound very loud even if they're cranking out the same amount of output as lesser speakers that do. As a result, they (and these PSAs) are less fatiguing and more enjoyable to listen to, particularly over long stretches.

You are hitting THX reference levels down to 20hz, so you have already reached the promised land.

I don't know what equalizer options you have, but I would try to get rid of the +5dB peak at 70hz. I would strive for a flat or slightly downward curve, with 20hz being the loudest.

Not long ago I watched a version of a movie where the mix was boosted from 70-100hz. It didn't sound good. (The same movie, played from different sources, had audio that was mixed differently.) I think eliminating this peak will give you a more transparent low frequencies. I'm just working this out as I type, but I believe boosting the bass frequencies has an effect similar to adding harmonic distortion to the sub frequencies.

(Every natural sound has overtones, and harmonic distortion is overtones made by the speaker that are unwanted/ not in the original sound. So a 35hz sound will have an octave at 70hz...and if the speaker is louder at 70hz than it is at 35hz, the 70hz overtone in the recording will be louder than it should be....so it is similar to if the sub driver with a flat EQ was producing 2nd order harmonic distortion (i.e. 70hz). I think I just figured this out, the why a downward sloping response curve sounds best. But if anyone out there disagrees, I'd be curious what you think.)
 
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mj30250

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You are hitting THX reference levels down to 20hz, so you have already reached the promised land.

I don't know what equalizer options you have, but I would try to get rid of the +5dB peak at 70hz. I would strive for a flat or slightly downward curve, with 20hz being the loudest.
Not that it matters since those subs are no longer in play, but the compression sweeps were done with the crossover disabled, hence the 70Hz bump. The normal sub response was as shown in the first post.
 

StigErik

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It's a pretty chart, but you really need to show us down to -40dB from the average SPL.

Sure. Here's at 90 dB SPL. I think that represents the maximum SPL I get when listening to music. Most of the decay below 30 Hz will fall below 0 phon and thus be inaudible at this SPL. There's still some clutter around 60 Hz that I want to get rid of, just to make the graphs look more impressing :cool:

StigErik-DBA-WF3.png
 

Andysu

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i not been in the THX cinema for few days , i may do the REW sub again

8n2ziy.gif
 

My adventures in stereo

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Very nice bass response
Was surprised to see that you are calibrating for around 100db SPL
THX levels are 85db , right ?
I have been adjusting my gain levels to reach around 85 db, for calibration
Also at higher SPL levels, as you noted, the ream creaks, booms etc, which is not ideal
 

StigErik

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I find 85dB too loud at home, mostly because movies on DVD/Bluray are mastered too hot. I usually set my volume somewhere between-12 and -8 dB.
 

Bugal1998

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Very nice bass response
Was surprised to see that you are calibrating for around 100db SPL
THX levels are 85db , right ?
I have been adjusting my gain levels to reach around 85 db, for calibration
Also at higher SPL levels, as you noted, the ream creaks, booms etc, which is not ideal

Target Reference level depends on room size. Commercial cinemas (I.E. auditorium sized rooms) target 85db with a -20db signal. Hometheater sized rooms should target 76-79db depending on their size, with the smallest rooms targeting 76 on up to 79 for larger home theaters (~5000 cubic ft.).
 

StigErik

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Why would the reference level depend on the room size? Related to room decay, or what?
 

Bugal1998

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Why would the reference level depend on the room size? Related to room decay, or what?

I'm not entirely clear why, but your hypothesis is as good as any I've seen.

See pg. 36, table 10.2 in the ATSC pdf linked here:

 

Chromatischism

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Recently I felt compelled to upgrade the subwoofers in my main setup (prompted by audible chuffing during loud, heavy sub-bass material), and I ended up ordering a pair of Monolith 15" V2s a couple weeks ago as they were temporarily made available at a very appealing sales price. I was finally able to put them through their paces over a lot of very loud music and movie material earlier today. The "listening area" for these is not large at roughly 2000 cubic ft, but one side of the room opens to a large basement, and the floor is a concrete slab sitting under medium thickness carpet. So while it's not bad, it's not exactly the most friendly subwoofer environment in existence.

Subjectively, these Monoliths sound exceptionally good. I have yet to notice any audible signs of distortion, strain, mechanical noise, or port chuffing under normal use. They present as extremely clean, short of the multitude of creaks, rattles, and buzzes that they bring out of the house at high volumes. Yes, I can drive the ports into noticeable turbulence by running sub-20Hz sinewaves, but in normal music / movie material that contains strong amounts of ULF content, it's essentially (if not completely) inaudible, which is in happy contrast to the 15" subs that they replaced. Below is their summed response after positioning them and running Audyssey XT32 (I've not brought out the MiniDSP yet as I haven't felt the need). As you can see, they are reasonably neutral and flat to nearly 10Hz in-room prior to dialing in any sort of house curve.

Rectangle Font Line Slope Parallel



Output wise, for music specifically, they appear to be far more capable than my needs and preferences require. If anything, it's often helpful to tone them down for music rather than the opposite. They integrate very well with my mains, and issues with the room/house itself not withstanding, I don't think I could be much (if at all) happier with their music performance in this space.

For home theater use, I am similarly thrilled, and again, run them with plenty of headroom in the tank. For reference, each sub is sitting close to +6dB on the gain knob (this is well below max as the Monolith's analog gain is logarithmic and scales up rapidly towards the higher portion of the dial), with trim levels maintained around -9.0dB on the Denon AVR. They are approximately 10-11ft distant from the MLP. Among many other things, I watched some scenes from the Dune 4K Blu-Ray. Spinning up the volume close to reference during some of the heavy bass scenes was ridiculous. The pressure from the sub-bass and punch from the midbass was something else, and I felt quite disoriented when I stood up (in a good way, of course!). For me, as much fun as this was, and even though the subs did not appear to be at all phased by the situation, pushing the volume even further was causing things to get legitimately uncomfortable. The house was making sounds that I had never heard before, and my body hasn't been rattled like that since riding in stupidly loud competition sub cars many years ago. I could never sit down and simply watch a bass-heavy movie at that sort of output level, and I'm someone who is generally happy to watch a full-length film at volumes that could potentially incur an OSHA fine for lack of hearing protection.

So, while it sounds like I am here to simply give the Monolith 15" V2s a positive review (and I enthusiastically do), the primary purpose of this is to ask...given the multitude of bigger/badder subs out there (and the many owners who happily load up their rooms with them), what's left for me to gain in my space? Specifically, the Monolith 16" subs went on sale earlier this month at a crazy low price. I'd have likely jumped on the deal had the 15s not already been enroute and if I had some readily available means to get those 172lb monsters down the steps and into the basement. Something like the PSA TV1813M is also bigger and much more powerful, and while it's costlier, it has the benefit of being about the same weight as the 15" Monoliths, thanks in large part to its MDF (versus HDF) cabinet. But, let's say I magically dropped a pair of 16" Monoliths or those 18" (or even the 21") PSAs into the room. What would I expect to hear/feel? I'm already not pushing the 15s to their limits, the in-room response and tactical feel are satisfactory, and distortion is presumably below audible levels. I'm truly curious. Help put my rampant FOMO to rest (or go ahead and make it much worse!). Thanks.
As the owner of a pair of Rythmik FV15HP2's, I know the feeling of reaching the point where you're finally satisfied after years of having lesser subs.

NZ6_5348 • JPEG 50%.jpg


However, I don't experience quite what you describe. I've been in stupidly loud cars and know the kind of bass you're talking about. The kind that rattles your ribcage. But, that could be because I'm running a different overall curve. If I listen to music with what you describe, it doesn't sound balanced. But this does. Subs only in a small room:

2xRythmik FV15HP Rear Closet Sub.png

The integration with the main speakers is seamless.

My favorite test is the Blade Runner 2049 opening scene up to the point where he lands the police car at the farm. The whole room gets involved.
 
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Chromatischism

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10 Hz with low distortion is definitely not audible, but at enough SPL it can be felt.
Definitely.

It also depends on the construction of the sub and how it's placed in the room.

Dual-opposed subs that cancel all vibrations or subs that are isolated from the floor don't give you the same visceral experience as a single powerful driver or sub that is coupled to the floor.

Here were a pair of dual-opposed subs that produced ridiculous measurements in my room. However the movie experience compared to the FV15HP2's was lacking, even with the Rumble Filter off. So the chart in this case does not tell the whole story.

Rythmik G22 Pair Extension.png


Note this was before I showed this to JohnPM and asked if he could add a label for sound < 20 Hz, which is why there is no label beyond Sub bass.
 

Great Sun Jester

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As the owner of a pair of Rythmik FV15HP2's, I know the feeling of reaching the point where you're finally satisfied after years of having lesser subs.

View attachment 367577

However, I don't experience quite what you describe. I've been in stupidly loud cars and know the kind of bass you're talking about. The kind that rattles your ribcage. But, that could be because I'm running a different overall curve. If I listen to music with what you describe, it doesn't sound balanced. But this does. Subs only in a small room:

View attachment 367578
The integration with the main speakers is seamless.

My favorite test is the Blade Runner 2049 opening scene up to the point where he lands the police car at the farm. The whole room gets involved.
Nice. Very nice. Fury is pretty good also.
 

Chromatischism

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You are hitting THX reference levels down to 20hz, so you have already reached the promised land.

I don't know what equalizer options you have, but I would try to get rid of the +5dB peak at 70hz. I would strive for a flat or slightly downward curve, with 20hz being the loudest.

Not long ago I watched a version of a movie where the mix was boosted from 70-100hz. It didn't sound good. (The same movie, played from different sources, had audio that was mixed differently.) I think eliminating this peak will give you a more transparent low frequencies. I'm just working this out as I type, but I believe boosting the bass frequencies has an effect similar to adding harmonic distortion to the sub frequencies.

(Every natural sound has overtones, and harmonic distortion is overtones made by the speaker that are unwanted/ not in the original sound. So a 35hz sound will have an octave at 70hz...and if the speaker is louder at 70hz than it is at 35hz, the 70hz overtone in the recording will be louder than it should be....so it is similar to if the sub driver with a flat EQ was producing 2nd order harmonic distortion (i.e. 70hz). I think I just figured this out, the why a downward sloping response curve sounds best. But if anyone out there disagrees, I'd be curious what you think.)
I think it has to do with human hearing and other effects, some natural and some imposed during content creation. Human hearing'a sensitivity to absolute levels of low frequencies is relatively low. Interestingly though, our ability to discern differences in bass levels (difference between 40, 50, 60 Hz) is high. This in combination with:

1. Bass' ability to modulate the effects of mid to high frequency listening fatigue, and
2. Attenuated low frequency content in modern movie soundtracks

...means we like elevated low frequencies for balanced sound.

ISO 226-2003 White.png
 
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