How do you know when you have enough low end? - AVS Forum
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post #1 of 35 Old 07-21-2009, 08:10 PM - Thread Starter
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How do you know when you have enough low end? Most of the subs talked about here are very powerful, so how do you know when you have enough? Is the ans, when you can listen to a given source at your desired playback level?

Then if so why do some have quad X or dual Y, when in their own right as a single sub they are very powerful.

So let me put this into my situation... I bought two ULS-15, I have a nightmare of a room, 25x25x10 but 25% of the walls are glass and 15% is open to the rest of the house.

I have moved the subs all around (to locations that I am allowed to have them) and have found that having them in the front corners produces the max output and flattest FR. I have the subs gain matched (one is at 10 the other 11 on the dial) but in order to get the optimal level for HT (level recommended from Hsu worksheet, 95dB with the 50Hz tone from the Hsu CD) I have to have the AVR level sub at +9. When I compare the levels using the AVRs pink noise the sub is 7dB hot (if I run it flat I feel and hear little low end).

Now sometimes when I listen to movies I think it sound good but a lot of the time I'm left thinking that I am missing something.

So that brings me back to my original question, How do you know when you have enough low end? And how do you know when you have enough? I have two very powerful, great sounding subs (I've listened to them in a different setting and they can sound great) and I keeping going back and forth second guessing my decision, sometimes it sounds great but then others I just get disappointed. Am I just expecting too much from these subs when they are in a room such as mine? Or have I just been reading too much on here about output and some true bass heads

Should I throw more output at it and try two PB13 Ultras, or even the current king of the hill the SubMerives X2... I just can not go larger than these two, infact I'm pushing it with that.




I just want to add, I think the ULS-15 is a great product and when set up in the right room sounds fantastic... In fact if I were allowed to set up an HT in the basement I would again look to the ULS-15s but that is not an option and I'm stuck with making the living room the best HT I can.
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post #2 of 35 Old 07-21-2009, 08:48 PM
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I think having enough low end is a matter of personal preference. What one person thinks is way more than enough might just be getting started for the next guy. If you are happy with the sound of your system, then it is enough. If you are second guessing anything, then you probably need more.

I can honestly say that I am on the other side of the coin. I feel that I have way more than enough, but I have only my system to compare it to. It is nice to have the GTG's so we can see what other people are using and share ideas and get honest opinions of different subs in the same setting.


Good luck,

Robert
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post #3 of 35 Old 07-21-2009, 08:53 PM
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In my opinion, the ULS pair should be capable of doing a pretty good job in your room.

Running the AVR sub output at +9 is not good! I wouldn't suggest any higher than +3. Raise the gain on the subs higher and lower the AVR output.

Have you actually measured your frequency response at your seating area or are you judging by ear that you have your subs positioned for the flattest response? If you measured it, can you reproduce it here?

How much bass is enough? You pretty much answered that. It is when you can listen at your desired levels, but without loss of cleanliness and without audible distortion. To do that, you need headroom. One needs a little more subwoofage than what is called for at your maximum listening levels in order to insure the bass sounds clean.

Folks often go with two or more powerful subs because it provides even more headroom, meaning more bass cleanliness, and it helps to even out the bass frequency response throughout the room.
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post #4 of 35 Old 07-21-2009, 09:01 PM
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enough is a subjective term. some will be happy with a single 12, and others will have 4 18's and still crave more.

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post #5 of 35 Old 07-21-2009, 09:07 PM
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There are a several factors at work regarding anchoring a system with good bass. Of course there's the depth (how deep), the flatness (in one seat and in all seats), and output level (how loud). To get loud, one unit will do if it's big enough (displacement, efficiency, amp power, etc.). Multiples can help, but not as much as it would seem it would. Flatness is due to sub design, placement, configuration, placement, and placement. Add that you want all seating areas to have good flat sound, then multiple units can greatly help. Depth is again due to unit design and placement again.

So, do you have enough? Likely not if you're asking (sorry). If you're getting close to the max output during loud scenes, then the units are working hard and likely getting way out of their linear rangse and no longer going to be great quality sound. Play some familiar passages at a good loud listening level you like. Then do it again with just the subs (unplug the mains) and see if they sound good or near their limits. I've done this and was pleasantly suprised how good things still sounded bass wise even obnoxiously loud. I've learned it's my mains (and mains amp) that's really hurting things now.

Adding more ULS's would be one option (and a good one) since you'll have more flexibility with placement due to their size and the fact they'll match timbre, etc. with your existing units. You can stack a couple if only output increase is needed, and/or space them around for flatter all room response. Having a unit closer to a seating position will also generate a more visceral experience, but sometimes be distracting and locatable.

I re-read your question(s) and can't really help much with configuration in your setup. I'm not familiar with Hsu's test CD setup method. Perhaps they're optimizing the sub's setup, but you may still need to properly integrate it into the system level wise, so having the receiver at +9 isn't necessarily a bad thing if it's matched/balanced with the mains. When you use the receiver's pink noise generator, are you measuring with a Radio Shack SPL meter? Have you applied the correction factors to the SPL meter readings. That may be throwing you off. If it seems too quiet it may be correct, but you may also be skewed by what you've heard in the past. In stores, subs are 99% of the time set WAY too hot. That's what'll usually sell a system to the averago Joe.

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post #6 of 35 Old 07-21-2009, 09:39 PM
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You get used to bass. It's a drug. With two A7S-450s I'm reasonable happy now. If I lived in a rural area and a more solid house (it's amazing how well wood framing transmits 30hz) I'd have no qualms about just going completely nuts. Be aware that placement is 50% of the game. Your subs WILL sound like pure ass in some positions. And it's not just DBs. I have my subs behind the seating area firing back even though the meter tells me 2db more can be had by placing them to the sides, because I can FEEL them much better there. (Advantage of having suspended wood floors, no need for a Buttkicker...)
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post #7 of 35 Old 07-22-2009, 02:27 AM - Thread Starter
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Mojomike,

below is my FR, I just received an external sound card but have not had time to set up PEW... Readings are directly from an RS SPL from listening position with MV at "0" using the Hsu test tone CD.

Sub
16Hz - 75
20Hz - 78
25Hz - 83
31.5Hz - 80
40Hz - 87
50Hz - 91
63Hz - 92
Mains
100Hz - 87
125Hz - 92
160Hz - 93
200Hz - 94

these tests were done with sub at +3 (which is the level matched to the mains using the AVRs pink noise), Other speakers levels were are +-1 from 0, apart from the center which was +3. With this FR Hsu worksheet recommended a level optimized for HT of 95dB using the 50Hz tone

I would agree that the ULS do a pretty good job, its just there are time when I think that I'm missing out.

I will try uping the sub gain and lowering the AVR sub level.
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post #8 of 35 Old 07-22-2009, 03:25 AM
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How about moving the subs close to your listening position. My room is not quite as big as yours but I have carpet over concrete floors and it makes my room hard to drive. I have my sub placed directly behind my couch.

With your measurements it looks like you do need more low end. You are down 16 db at 16 hz. In room should be flat or close to it.
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post #9 of 35 Old 07-22-2009, 03:55 AM
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"How do you know when you have enough low end?"

When you turn the volume down instead of up.
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post #10 of 35 Old 07-22-2009, 04:16 AM
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Quote:
Originally Posted by vivid View Post

Mojomike,

below is my FR, I just received an external sound card but have not had time to set up PEW... Readings are directly from an RS SPL from listening position with MV at "0" using the Hsu test tone CD.

Sub
16Hz - 75
20Hz - 78
25Hz - 83
31.5Hz - 80
40Hz - 87
50Hz - 91
63Hz - 92
Mains
100Hz - 87
125Hz - 92
160Hz - 93
200Hz - 94

these tests were done with sub at +3 (which is the level matched to the mains using the AVRs pink noise), Other speakers levels were are +-1 from 0, apart from the center which was +3. With this FR Hsu worksheet recommended a level optimized for HT of 95dB using the 50Hz tone

I would agree that the ULS do a pretty good job, its just there are time when I think that I'm missing out.

I will try uping the sub gain and lowering the AVR sub level.

At those settings, you are certainly not running hot. I'd leave the setting at +3 and dial in about 2 or 3 more db via the subs' gain.

What happened to the measurements between 63-100hz? That is a really critical area that provides much of the "kick" that you hear and feel and it shows how well the crossover between the sub and the mains is working. Very much of the bass you perceive lies in that zone. The measurement of that area should be done with the sub and mains playing together. It can indicate if there are any phase problems which can cause some cancellation and weakness in the crossover area.
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post #11 of 35 Old 07-22-2009, 04:41 AM
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You have over 6000 cf of "real" space PLUS the opening into the other room PLUS PLUS PLUS the base frequencies do not "see' the walls where the glass is so it (at certain frequencies) leaks out there as well.

If you can, borrow some additional subs from someone and use them WITH yours and see if it helps. If it turns out to be just needing to move more air, then you have a number of options: buy 2 more of what you have or sell what you have and buy two (or more) of something larger (SubMersives??)

I can't remember if you are using an EQ or not or does your processor has Audyssey.

Were the reading you posted adjusted for the errors in the RS Meter?

But I do understand your pain. I'm thinking of starting a 12 step program for the "bass deprived".

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post #12 of 35 Old 07-22-2009, 06:41 AM
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Quote:
Running the AVR sub output at +9 is not good! I wouldn't suggest any higher than +3. Raise the gain on the subs higher and lower the AVR output.

Mike, Im always curious about this opinion?

As long as the AVR is not sending max voltage out during peaks possibly inducing clipping why does it matter if its +9 or +3? What is more important is all the level matching but I guess I should go read the level matching, gain matching debates again.

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post #13 of 35 Old 07-22-2009, 06:51 AM
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Quote:
Originally Posted by penngray View Post

Mike, Im always curious about this opinion?

As long as the AVR is not sending max voltage out during peaks possibly inducing clipping why does it matter if its +9 or +3? What is more important is all the level matching but I guess I should go read the level matching, gain matching debates again.

To me, +9 seems like an extreme gain level to ask of the AVR when the same levels can be achieved by simply raising the gain on the sub. The point is, how can one know if the AVR is not sending out max voltage when playing heavy content at louder levels? To me it's playing it safe by keeping the sub-out levels at a conservative number.
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post #14 of 35 Old 07-22-2009, 06:54 AM
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Quote:
Originally Posted by mojomike View Post

To me, +9 seems like an extreme gain level to ask of the AVR when the same levels can be achieved by simply raising the gain on the sub. The point is, how can one know if the AVR is not sending out max voltage when playing heavy content at louder levels? To me it's playing it safe by keeping the sub-out levels at a conservative number.

What does the +9 value represent? dB increase?

Does the AVR ever send out a clipped signal through a Pre out? or its just increased voltage that could clip the amp.

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post #15 of 35 Old 07-22-2009, 07:14 AM
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Quote:
Originally Posted by penngray View Post

What does the +9 value represent? dB increase?

Does the AVR ever send out a clipped signal through a Pre out? or its just increased voltage that could clip the amp.

Pre-amps just like main amps have their maximum clean output levels. In the case of a pre-amp, it may amount to a few volts. The pre-amp output stage can put out a clipped signal if asked to excede whatever it's rated output voltage is. Since one usually has the option of raising the gain on the sub rather than risking clipping the pre-amp, why not do so?

As far as clippng the sub amp by too much input signal, I'm sure that may also be a possibilty. Again, why risk it if it can be easily avoided?
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post #16 of 35 Old 07-22-2009, 07:29 AM
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Quote:
Originally Posted by mojomike View Post

Pre-amps just like main amps have their maximum clean output levels. In the case of a pre-amp, it may amount to a few volts. The pre-amp output stage can put out a clipped signal if asked to excede whatever it's rated output voltage is. Since one usually has the option of raising the gain on the sub rather than risking clipping the pre-amp, why not do so?

As far as clippng the sub amp by too much input signal, I'm sure that may also be a possibilty. Again, why risk it if it can be easily avoided?


The rated output voltage is hard to find in specs, they tend to list the sensitivity rating. I can measure it though.

I agree with your point on why risk it but in the world of DIY subs and using Pro amps there are times where the output isnt good enough unless we have the AVR sub levels set to max ( Yes the amp trim is already at 100%)

So in certain cases there is a need, I was just curious to if there was any other reason other then exceed ouput voltage specs (which needs the volume turned really high).

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post #17 of 35 Old 07-22-2009, 07:45 AM
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Quote:
Originally Posted by penngray View Post

The rated output voltage is hard to find in specs, they tend to list the sensitivity rating. I can measure it though.

I agree with your point on why risk it but in the world of DIY subs and using Pro amps there are times where the output isnt good enough unless we have the AVR sub levels set to max ( Yes the amp trim is already at 100%)

So in certain cases there is a need, I was just curious to if there was any other reason other then exceed ouput voltage specs (which needs the volume turned really high).

I don't know of any other reason. Personally, I've never had a problem driving my EP2500 with the sub-out of my Denon receiver using output settings under "0".
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post #18 of 35 Old 07-22-2009, 07:47 AM - Thread Starter
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Ok guys,

Fortunately I work from home have been able to take some time to readjust the system.

I first gain matched the subs to a higher level. I pulled one sub to the middle of the room moved the gain up from 11 to 12, measured spl at 3' with a 50Hz tone, pulled the other sub to the same location and played the 50Hz tone and adjusted the gain so the SPL was identical to the first... The gains have moved from 11 and 10 to 12 and 11:30.

Next I put the subs back in their locations set the master volume to 0 and adjusted the AVR sub level so that I achieved 95dB for the 50Hz tone.

Sub is now set to +0.5,
center is +3
all others +-1 of 0

I then checked the levels of all speakers using the AVRs pink noise.

5.0 - 75dB
sub - 80dB

With the MV set to 0, I used the Hsu test tone CD to measure the SPL on a RS SPL meter (no corrections made below) from my listening position.

All speakers set to small, XO set at 100Hz

16HZ - 81dB
20Hz - 82dB
24Hz - 90dB
31.5 - 86dB
40Hz - 92dB
50Hz - 97dB
63Hz - 100dB
80Hz - 97dB
100Hz - 96db
125Hz - 96dB
160Hz - 93dB

I have to get a little work done now but my next task will be to listen to a LEF demo disk with the MV set to 0 and with the 5.0 speakers turned off, so I can focus on the low end.
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post #19 of 35 Old 07-22-2009, 07:53 AM
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That looks pretty decent especially if you factor in meter corrections. Now, what sort of levels can you comfortably achieve without noticeable distortion?
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post #20 of 35 Old 07-22-2009, 07:55 AM
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Penn, here is an interesting evaluation of a fairly typical Denon AVR.
http://www.soundandvisionmag.com/rec...-receiver.html
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post #21 of 35 Old 07-22-2009, 07:55 AM
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Quote:
Originally Posted by Decadent_Spectre View Post

"How do you know when you have enough low end?"

When you turn the volume down instead of up.

Very well said. The ultimate is to test your limits of comfort and not those of your system. Of course as soon as that point is reached, you might then grab an EQ and push the system a bit lower, or treat the room better and allow for higher listening levels...

In my personal history, after 4 SubMersives, you build a Terraform XL.

Yes, it's a vicious circle.

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post #22 of 35 Old 07-22-2009, 08:19 AM
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Quote:
Originally Posted by mojomike View Post

I don't know of any other reason. Personally, I've never had a problem driving my EP2500 with the sub-out of my Denon receiver using output settings under "0".

I wish that was true for my setup (with many brands of AVRs and pro amps) but there has been enough threads on that topic.

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post #23 of 35 Old 07-22-2009, 08:23 AM
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Trick question,

there is no such thing as enought low end

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post #24 of 35 Old 07-22-2009, 08:24 AM - Thread Starter
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Quote:
Originally Posted by mojomike View Post

That looks pretty decent especially if you factor in meter corrections. Now, what sort of levels can you comfortably achieve without noticeable distortion?

what is the best way to test for that? With test tones (if so which frequency), movies or music? Then just play the source raising the MV till I can hear distortion, compression, clipping? Do I need to use the spl for this or is my ear sufficient?
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post #25 of 35 Old 07-22-2009, 08:24 AM
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Quote:
Originally Posted by mojomike View Post

Penn, here is an interesting evaluation of a fairly typical Denon AVR.
http://www.soundandvisionmag.com/rec...-receiver.html

thx, thats a good test breakdown.

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post #26 of 35 Old 07-22-2009, 08:48 AM
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Quote:
Originally Posted by vivid View Post

what is the best way to test for that? With test tones (if so which frequency), movies or music? Then just play the source raising the MV till I can hear distortion, compression, clipping? Do I need to use the spl for this or is my ear sufficient?

Take some good movie source material with known strong bass content. Dark Knight, Cloverfield, WOTW, Iron Man, etc. Play it at the loudest volume that you might wish to listen. Does the bass soound clean to your ears? Now at that same volume, turn off all the main speakers and and listen to the sub only. do you hear any signs of distress or other bad noises? If the subs are not struggling, you have enough bass.
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post #27 of 35 Old 07-22-2009, 10:10 AM
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Quote:
Originally Posted by vivid View Post

what is the best way to test for that? With test tones (if so which frequency), movies or music? Then just play the source raising the MV till I can hear distortion, compression, clipping? Do I need to use the spl for this or is my ear sufficient?

Here's your graph with the RS meter corrections applied. The extreme ends of the graph are guesses because I don't have the 10Hz number and i was too lazy to read the 200Hz number earlier in the thread, but it should be darned close to what you have.

Keep in mind that the numbers you provided are 1/3 octave and thus the graph reflects 1/3 octave smoothing.

You need to set up REW or TrueRTA. Set the mic at the LP and run a sweep. Then raise the MVL by 3dB and run another sweep. Continue that process until the sub sounds distressed, or the last sweep doesn't reflect a 3dB increase in magnitude.

Post the results and we'll be able to get to some conclusions fairly quickly.



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post #28 of 35 Old 07-22-2009, 10:24 AM
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post #29 of 35 Old 07-22-2009, 10:53 AM
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When you can take any material on any format: BR,DVD,CD,file,record,WOTW's,PULSE,1812 overture, Danley Finale, etc.... whatever, ANYTHING, without fear or trepidation of what may be on it, turn your system up 5 clicks past where you would personally ever run it and it just reproduces it, without obvious signs of distress, while sounding really good all the way from that level down to a whisper. This becomes increasingly more difficult the lower you want to reach while maintaining the same amount of headroom and dynamics. If you are fine with 25hz extension it's one thing but if you wanted to maintain it down to 10hz or even lower you'll need much more firepower than the 25hz system.
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post #30 of 35 Old 07-22-2009, 12:20 PM
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Quote:
Originally Posted by mojomike View Post

Take some good movie source material with known strong bass content. Dark Knight, Cloverfield, WOTW, Iron Man, etc. Play it at the loudest volume that you might wish to listen. Does the bass soound clean to your ears? Now at that same volume, turn off all the main speakers and and listen to the sub only. do you hear any signs of distress or other bad noises? If the subs are not struggling, you have enough bass.

In addition to Mike's advice, try this if you have a SPL meter. This is from an email from Ed from SVS. I have a PB10, and asked the best way to tell if it is enough sub for my room at my listening levels...Here you go

"Calibrate the subwoofer flat/even with the speakers. If your speakers are calibrated to 75 dB, then calibrate the subwoofer to 73 dB (C/Slow on the meter). This is because the meter reads about 2 dB low on the subwoofer test tone.

Play the demanding scene starting at -20 dB Reference. Note the bass peak on the SPL meter (C/Fast) for a given time stamp (some notable event or scene). Let the subwoofer cool off for 15-20 seconds, and then increase the master volume 3 dB and loop the scene again. The SPL peak should increase by 3 dB.

There will come a point where the subwoofer no longer plays 3 dB louder and will start to compress. You might only see a 1 dB increase for example. Once you reach this point, back off the master volume a few dB so the subwoofer is no longer compressing peaks. Compare this master volume setting to your normal/preferred setting on that DVD.

If you find that your preferred master volume setting is higher than the max uncompressed limit of the subwoofer, then you should consider adding a second subwoofer or upgrading to a more powerful model. If the subwoofer is still operating linearly at your preferred playback level, then you are OK."
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