How to figure out if my subwoofer can hit reference? - AVS Forum
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post #1 of 49 Old 11-01-2012, 09:49 AM - Thread Starter
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So I have a pair of Sho-10s and a VTF-3.4 in my room very large room. Based on the calculator here (http://myhometheater.homestead.com/splcalculator.html), my Sho-10s can hit reference in my room (85 db w/ 20 db of headroom) with 125 watts of power, which I have read the Denon 4311 can do when it is only powering 2 channels.

So now I am trying to figure out if my subwoofer can handle up to 115 db, or if it will run out of steam and start clipping while the sho-10s will be playing reference (at least theoretically w/ sufficient headroom). I have the crossover point for the sub at 100hz. Is there a calculation to figure this out? How can i figure out if my sub isn't evenly matched w/ the sho-10s at playing reference?

Just as a side note, I have NHT classic fours which i loved, but now that I have the sho-10s set up, for HT it was a revelation. With the same amount of wattage I am feeding the Sho-10s, the NHTs would only be able to do 93db max. According to that calculator link, it would take close to 2,000 watts to make the NHTs play reference, which is clearly impossible for those speakers. That would probably explain why I thought the NHTs were painful to listen to for HT when I put it loud and the Sho-10s are really comfortable and not painful at all, and everything just seems so much more fun (dynamic I guess is the word people use around here).
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post #2 of 49 Old 11-01-2012, 10:19 AM
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I don't think a single VTF3 is hitting THX reference unless you are sitting right in front of the woofer or are listening in a closet. You will need a SPL meter to see what kind of output you are getting. Remember you also need low distortion at 115 db, so the sub has to be hitting that clean. There are very few commercial subs that can hit THX reference in a normal room.
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post #3 of 49 Old 11-01-2012, 10:42 AM
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To get a rough approximation of how much output you'll get, you can look at the CEA 2010 max burst numbers for the VTF 3.3 done by Ilkka here:

http://www.hometheatershack.com/forums/subwoofer-tests-archived/5748-cea-2010-standard-compilation.html

Those are 2 meter ground plane RMS figures, so you can fiddle around with gains from corner loading, losses from being further away from the sub, etc to get an idea of what kind of output you should be getting in room. I'd also add that while the LFE channel calls for a peak output of 115dB, when you're utilizing bass management and sending the bass from your other channels to the subwoofer, you're going to be increasing it's potential output requirement. For a 5.1 setup, a subwoofer could potentially be asked to deliver 123dB at the listening position.
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post #4 of 49 Old 11-01-2012, 10:46 AM - Thread Starter
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Originally Posted by shadyJ View Post

I don't think a single VTF3 is hitting THX reference unless you are sitting right in front of the woofer or are listening in a closet. You will need a SPL meter to see what kind of output you are getting. Remember you also need low distortion at 115 db, so the sub has to be hitting that clean. There are very few commercial subs that can hit THX reference in a normal room.

Well I am sitting nearfield, but that sounds like it isn't nearly enough.

I guess what I am having difficulty w/ is knowing whether I am getting clean/low distortion output at 115db if I am testing from an SPL meter.

Seems like an expensive way of testing, but is what people do just buy more and bigger subs and just hope they end up getting clean output at reference levels for HT?
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post #5 of 49 Old 11-01-2012, 11:05 AM - Thread Starter
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Originally Posted by Steve1981 View Post

To get a rough approximation of how much output you'll get, you can look at the CEA 2010 max burst numbers for the VTF 3.3 done by Ilkka here:
http://www.hometheatershack.com/forums/subwoofer-tests-archived/5748-cea-2010-standard-compilation.html
Those are 2 meter ground plane RMS figures, so you can fiddle around with gains from corner loading, losses from being further away from the sub, etc to get an idea of what kind of output you should be getting in room. I'd also add that while the LFE channel calls for a peak output of 115dB, when you're utilizing bass management and sending the bass from your other channels to the subwoofer, you're going to be increasing it's potential output requirement. For a 5.1 setup, a subwoofer could potentially be asked to deliver 123dB at the listening position.

This is excellent, thanks!

As far as bass management sending the bass from other channels to the sub (in addition to the LFE it is already handling), isn't the bass from those channels limited to 105 db for HT? So although the amount of work the sub does is increased, it will still be 115 db of peak output?
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post #6 of 49 Old 11-01-2012, 11:29 AM
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Originally Posted by economyte View Post

This is excellent, thanks!

Happy to help!
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As far as bass management sending the bass from other channels to the sub (in addition to the LFE it is already handling), isn't the bass from those channels limited to 105 db for HT? So although the amount of work the sub does is increased, it will still be 115 db of peak output?

Each of the satellite channels (which are full range channels) can peak at up to 105dB, and they can (in theory, if not in practice) all peak simultaneously along with the LFE channel. It's rare (if not totally unknown) in real world content, but it's possible. In this instance though, if you're rerouting all those peaks to your Hsu, it would be expected to produce 105dB + 105dB + 105dB + 105dB + 105dB + 115dB. Plugging that into a handy dandy SPL addition calculator:

http://www.doctorproaudio.com/doctor/calculadores_en.htm

and then selecting in phase, you'll get 123.2dB.
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post #7 of 49 Old 11-01-2012, 12:33 PM - Thread Starter
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Happy to help!
Each of the satellite channels (which are full range channels) can peak at up to 105dB, and they can (in theory, if not in practice) all peak simultaneously along with the LFE channel. It's rare (if not totally unknown) in real world content, but it's possible. In this instance though, if you're rerouting all those peaks to your Hsu, it would be expected to produce 105dB + 105dB + 105dB + 105dB + 105dB + 115dB. Plugging that into a handy dandy SPL addition calculator:
http://www.doctorproaudio.com/doctor/calculadores_en.htm
and then selecting in phase, you'll get 123.2dB.

Very interesting, wouldn't have expected that. Very useful information.
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post #8 of 49 Old 11-01-2012, 01:22 PM
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Originally Posted by economyte View Post

Well I am sitting nearfield, but that sounds like it isn't nearly enough.
Getting big near-field output depends on how near-field you are, and how the sub is set up.
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I guess what I am having difficulty w/ is knowing whether I am getting clean/low distortion output at 115db if I am testing from an SPL meter.
Seems like an expensive way of testing, but is what people do just buy more and bigger subs and just hope they end up getting clean output at reference levels for HT?

Testing with an SPL meter is the only way to be sure about output, and you will need a good mic with a good sound input jack on your computer with a program like REW if you want to make sure the FR is nice and even. Some people bother to check if they can achieve THX reference at their listening position, and some dig deep in REW to be sure they are getting everything just right, but most just enjoy their subs without worrying about hitting specific output goals.
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post #9 of 49 Old 11-01-2012, 01:33 PM
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+1. Plus 115 dB is awfully loud; I need my hearing so don't really care about being able to play that loudly. The usual counter argument is needing the headroom for low distortion etc. but in practice few subs (or speakers) have low distortion at that level.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #10 of 49 Old 11-01-2012, 02:03 PM - Thread Starter
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Originally Posted by shadyJ View Post

Getting big near-field output depends on how near-field you are, and how the sub is set up.
Testing with an SPL meter is the only way to be sure about output, and you will need a good mic with a good sound input jack on your computer with a program like REW if you want to make sure the FR is nice and even. Some people bother to check if they can achieve THX reference at their listening position, and some dig deep in REW to be sure they are getting everything just right, but most just enjoy their subs without worrying about hitting specific output goals.

Yea, would really just like to sit back and enjoy it ... but the anal person in me just won't let me. I guess my main issue/concern is that I know the Sho-10s can be pushed pretty hard cleanly w/ the amplification i have, and i'm trying to figure out how hard I can push the sub as well (since the volume control would be moving them both in tandem). So if I'm listening at -5 on the receiver (post audyssey calibration), that would generally mean the sub would need to be able to do 105 db cleanly. Sounds like the only way I can figure that out is w/ an SPL meter and REW.
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post #11 of 49 Old 11-01-2012, 04:21 PM
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+1. Plus 115 dB is awfully loud; I need my hearing so don't really care about being able to play that loudly. The usual counter argument is needing the headroom for low distortion etc. but in practice few subs (or speakers) have low distortion at that level.

High output at low frequencies isn't nearly as dangerous as mid and high frequencies.
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post #12 of 49 Old 11-01-2012, 05:43 PM
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Agreed, though 115 dB at LF still packs a wallop.

OTOH, I am glad I am on the back side of my horn; pity the woodwinds in front of me who have to endure it when the conductor wants more (rare, but happens).

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #13 of 49 Old 11-01-2012, 06:52 PM
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Don't you guys have to wear hearing protection?
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post #14 of 49 Old 11-01-2012, 06:55 PM
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Last time I measured with an SPL meter, my single PB12-Plus corner loaded and near field had no problems hitting 115db at my listening position. However, it is just too damn loud for me to watch an entire movie like that.
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post #15 of 49 Old 11-01-2012, 07:52 PM
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Guys - one thing is missing from this discussion. You may be hitting 115dB with a single 12 or 15" sub but you most certaintly aren't keeping your native flat eq frequency response at those levels. Probably just hitting 60 or 70hz and above, and completely compressing at the lower end of the spectrum.

The number of commerical single subs that can hit reference level playback without compression you can probably count on 1 hand and they all cost a couple thousand + per unit.

To provide an excellent example of what I'm talking about take a look at this axiom sub review I just stumbled across at home theater shack with two 12" subs in one large enclosure.
http://www.hometheatershack.com/forums/sub-zone-subwoofer-testing/62085-axiom-ep800.html


The manufactorer posts this graph
file.php?n=9463

The specs read
Anechoic Resp. +/- 1dB 13 - 150 Hz Frequency Graph
Anechoic Resp. +/- 3dB 12 - 150 Hz

Sounds great right?

However, in real life use compression occurrs at the lowest frequencies because it takes more power and more driver excursion to keep linear progression in spl at the 20hz end of the spectrum.

SO

In reality you get this in real life measurements which is far less impressive.
file.php?n=9612


Somewhere between 90hz and 95hz this sub stops raising spl linearly, and your frequency response starts looking more like a mountain than a plain. In practice this means that the listener is missing all the depth of note that should be there.


To hit 115dB at 20hz and still have increased the spl without affecting the frequency response takes a big old ported 18" with massive excursion or a couple high quality --- (read expensive) sealed subs typically. A 12" sub wouldn't do this until it had a half dozen companions in most cases.

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post #16 of 49 Old 11-02-2012, 07:45 AM
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Guys - one thing is missing from this discussion. You may be hitting 115dB with a single 12 or 15" sub but you most certaintly aren't keeping your native flat eq frequency response at those levels....The number of commerical single subs that can hit reference level playback without compression you can probably count on 1 hand and they all cost a couple thousand + per unit...To hit 115dB at 20hz and still have increased the spl without affecting the frequency response takes a big old ported 18" with massive excursion or a couple high quality --- (read expensive) sealed subs typically. A 12" sub wouldn't do this until it had a half dozen companions in most cases.

It largely depends on the room, the subwoofer(s) in question, and of course how one feels like defining "reference level".

As one example, a Rythmik FV15HP costs a good amount south of $2000, and it exhibits excellent performance with respect to compression up until it hits the limits. It also delivers prodigious output, as it was measured by Josh Ricci to deliver 117dB @ 32Hz, 108dB @ 20Hz, and 102dB @ 16Hz, all at 2 meters ground plane per Josh's CEA-2010 Max Burst RMS sheet.

So how do those numbers compare with "reference"? Well, lets take a look at a THX Ultra 2 certified subwoofer:
http://mediacdn.shopatron.com/media/mfg/3579/media_document/live_1/KW120THX.pdf?1308178357

If you let your eye wander on that sheet, you'll assuredly find the section of the spec sheet marked "Maximum Acoustic Output", and you'll note those figures are for a pair of colocated subwoofers at 1 meter, 1/8th space (corner loaded). To compare them with the above figures that Josh measured, you'll have to subtract 18dB, 6dB for going from 2 meters to one, and 12dB for going from 1/8th space to 1/2 space. Doing that, you'll get 112dB @ 30Hz, 104dB @ 20Hz, and 96dB @ 15Hz. I'd daresay the FV15HP doesn't perform too shabby with respect to those numbers, which THX certifies is sufficient for "reference level" in a room up to 3000 cubic feet. Of course if your definition of "reference" demands flat response down to 3Hz, then obviously YMMV.
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It largely depends on the room, the subwoofer(s) in question, and of course how one feels like defining "reference level".
As one example, a Rythmik FV15HP costs a good amount south of $2000, and it exhibits excellent performance with respect to compression up until it hits the limits. It also delivers prodigious output, as it was measured by Josh Ricci to deliver 117dB @ 32Hz, 108dB @ 20Hz, and 102dB @ 16Hz, all at 2 meters ground plane per Josh's CEA-2010 Max Burst RMS sheet.
So how do those numbers compare with "reference"? Well, lets take a look at a THX Ultra 2 certified subwoofer:
http://mediacdn.shopatron.com/media/mfg/3579/media_document/live_1/KW120THX.pdf?1308178357
If you let your eye wander on that sheet, you'll assuredly find the section of the spec sheet marked "Maximum Acoustic Output", and you'll note those figures are for a pair of colocated subwoofers at 1 meter, 1/8th space (corner loaded). To compare them with the above figures that Josh measured, you'll have to subtract 18dB, 6dB for going from 2 meters to one, and 12dB for going from 1/8th space to 1/2 space. Doing that, you'll get 112dB @ 30Hz, 104dB @ 20Hz, and 96dB @ 15Hz. I'd daresay the FV15HP doesn't perform too shabby with respect to those numbers, which THX certifies is sufficient for "reference level" in a room up to 3000 cubic feet. Of course if your definition of "reference" demands flat response down to 3Hz, then obviously YMMV.

So here is the link on hometheatershack (http://www.hometheatershack.com/forums/subwoofer-tests-archived/5761-hsu-vtf-3-mk3-maximum-extension.html) on the VTF-3.3 (assuming the VTF-3.4 tests somewhat similar to the VTF 3.3).

If I am reading this right, there is a lot of distortion below 50hz and compression isn't linear above 100db?

So my plan was to spend a total of up to $1500 on subs, and I decided to buy one VTF-3.4 now and add another later (for both, would put me around $1500). But based on what I am reading, two non-colocated VTF-3.4's wouldn't simply won't be able to hit lower frequencies w/ +100 db without compression and lots of distortion.

So what would you recommend, buy one of the biggest subs I can afford (and forget about multiple subs - VTF 3.4 is the largest physical size I can do when doing multiple subs)? Even considering the sub will be corner loaded and nearfield, is this my only shot at +100 db w/out compression?
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post #18 of 49 Old 11-02-2012, 09:13 AM
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Quote:
Originally Posted by economyte View Post

If I am reading this right, there is a lot of distortion below 50hz and compression isn't linear above 100db?

Correct.
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So my plan was to spend a total of up to $1500 on subs, and I decided to buy one VTF-3.4 now and add another later (for both, would put me around $1500). But based on what I am reading, two non-colocated VTF-3.4's wouldn't simply won't be able to hit lower frequencies w/ +100 db without compression and lots of distortion.

It really depends on the room. Remember, those numbers are at 2 meters outdoors. If you're at 2 meters or less and the sub is corner loaded, you should see some boost from boundary gain. Also depending on your room size, you might see a little room gain to further lift low end output.

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So what would you recommend, buy one of the biggest subs I can afford (and forget about multiple subs - VTF 3.4 is the largest physical size I can do when doing multiple subs)?

The advantage of multiple subs is less about additional output and more about smoothing in room response. Me, I'm a lucky SOB that can get away with a single sub and end up with a gently rising low end response free of major dips up until about 150Hz at my listening position (and I'm a selfish SOB too, so that's the only position I care about biggrin.gif). If you're not so lucky and selfish, multiple subs makes a lot of sense, and you'll either want to pony up extra $$$ and live with having two large subs, or live with a little less output.
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post #19 of 49 Old 11-02-2012, 03:10 PM
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Quote:
Originally Posted by Steve1981 View Post

Quote:
Originally Posted by Archaea View Post

Guys - one thing is missing from this discussion. You may be hitting 115dB with a single 12 or 15" sub but you most certaintly aren't keeping your native flat eq frequency response at those levels....The number of commerical single subs that can hit reference level playback without compression you can probably count on 1 hand and they all cost a couple thousand + per unit...To hit 115dB at 20hz and still have increased the spl without affecting the frequency response takes a big old ported 18" with massive excursion or a couple high quality --- (read expensive) sealed subs typically. A 12" sub wouldn't do this until it had a half dozen companions in most cases.

It largely depends on the room, the subwoofer(s) in question, and of course how one feels like defining "reference level".

As one example, a Rythmik FV15HP costs a good amount south of $2000, and it exhibits excellent performance with respect to compression up until it hits the limits. It also delivers prodigious output, as it was measured by Josh Ricci to deliver 117dB @ 32Hz, 108dB @ 20Hz, and 102dB @ 16Hz, all at 2 meters ground plane per Josh's CEA-2010 Max Burst RMS sheet.

So how do those numbers compare with "reference"? Well, lets take a look at a THX Ultra 2 certified subwoofer:
http://mediacdn.shopatron.com/media/mfg/3579/media_document/live_1/KW120THX.pdf?1308178357

If you let your eye wander on that sheet, you'll assuredly find the section of the spec sheet marked "Maximum Acoustic Output", and you'll note those figures are for a pair of colocated subwoofers at 1 meter, 1/8th space (corner loaded). To compare them with the above figures that Josh measured, you'll have to subtract 18dB, 6dB for going from 2 meters to one, and 12dB for going from 1/8th space to 1/2 space. Doing that, you'll get 112dB @ 30Hz, 104dB @ 20Hz, and 96dB @ 15Hz. I'd daresay the FV15HP doesn't perform too shabby with respect to those numbers, which THX certifies is sufficient for "reference level" in a room up to 3000 cubic feet. Of course if your definition of "reference" demands flat response down to 3Hz, then obviously YMMV.

it requires 2 of those KW120THX subwoofers to meet THX certification according to the article's text


yes it absolutely matters how you would define reference for this discussion to progress....But to me hitting 115dB at 70hz and hitting 95dB at 20hz because of compression or amp, or port limitation is not really going to get my excitement engine revved up.

.......reading somewhat between the lines

It appears that THX Ultra 2 reference requires the subs extend to 20hz (-6dB) and must be capable of playing 85dB + 20dB for headroom within that frequency response requirement in a 3000 cubic foot room.


http://www.thx.com/consumer/home-entertainment/audio/thx-certified-speakers/
http://www.thx.com/consumer/home-entertainment/home-theater/thx-certification-performance-categories/


http://www.avsforum.com/t/1321843/thx-ultra-2-subwoofer-spec-does-it-indicate-a-quality-product-or-is-it-pure-hype/0_20




But most of us enthusiasts here would consider hitting reference being able to hit reference level with the 20dB of headroom across the entire audible frequency spectrum all while avoiding compression, amp, and driver excursion limits......... -- and some of the most hardcore would say through the inaudible ~<20hz frequency spectrum as well. wink.gif

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post #20 of 49 Old 11-02-2012, 03:52 PM
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it requires 2 of those KW120THX subwoofers to meet THX certification according to the article's text

Indeed it does; however the max acoustic output spec is for two of them colocated, not a single.
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But most of us enthusiasts here would consider hitting reference being able to hit reference level with the 20dB of headroom across the entire audible frequency spectrum all while avoiding compression, amp, and driver excursion limits.........

As I said, judging by the measurements, the aforementioned FV15HP ought to accomplish those goals, at least in a small to medium sized room.

http://www.data-bass.com/data?page=system&id=51&mset=50

The long term power compression sweep shows it doing quite well right until the redline, passing even the 110dB sweep with minimal compression at 20Hz (it delivered 106.5dB in that pass). That's not too shabby in my book for being 2 meters ground plane.
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some of the most hardcore would say through the inaudible ~<20hz frequency spectrum as well. wink.gif

Like I said, YMMV. If you're a user who demands reference level output down to 3Hz, clearly you're going to need a heck of a lot more than a Hsu VTF 3.4 or even a FV15HP.
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YMMV?
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post #22 of 49 Old 11-02-2012, 04:46 PM
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YMMV?

Your mileage may vary.
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post #23 of 49 Old 11-02-2012, 07:18 PM
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Quote:
Originally Posted by Archaea View Post

To provide an excellent example of what I'm talking about take a look at this axiom sub review I just stumbled across at home theater shack with two 12" subs in one large enclosure.
http://www.hometheatershack.com/forums/sub-zone-subwoofer-testing/62085-axiom-ep800.html

PS: Thanks for the link. Looks like they've got a few other subs measured over there as well. Hadn't seen this new batch of measurements before.
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post #24 of 49 Old 12-11-2012, 08:37 AM
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Originally Posted by economyte View Post
So what would you recommend, buy one of the biggest subs I can afford (and forget about multiple subs - VTF 3.4 is the largest physical size I can do when doing multiple subs)? Even considering the sub will be corner loaded and nearfield, is this my only shot at +100 db w/out compression?

Physics is a bitch.

Accept that reference level bass is really, really, hard. Very few people have it, know about it, can afford it, and can do it right (out of the home theater users). 

It's easier and cheaper nowadays than it was ten years ago, and it'll be even easier ten years from now. I know this is disappointing now, though.

 

So, you can:

  1. Buy bigger / more subs. 
  2. DIY infinite baffle, plus maybe an in-room sub to smooth response.
  3. Accept that your bottleneck is your sub, and you can only do -5dBFS or -10dBFS. (I'm sure your speakers will still sound more dynamic than mine!)
  4. Compromise on the frequency response: as you turn it up closer to reference, your bass will be more diminished with the respect of the rest of the frequency response. Down 5-10dB at different bass frequencies. Or exhibit more distortion and not sound like it should.

 

#1 and #2 cost more money. #2 can be cheaper and might be an option if you don't want too many boxes in the room. It depends on your budget and will and skills.

 

#3 doesn't require more money and isn't a compromise on quality, just the level. Although if your at-seat response isn't smooth yet, you have more placement or EQ work to do. Or need another sub for the smoother response and 3dB of additional output.
 

#4 is something a lot of people, unfortunately, do. They figure "I spent $XXXX dollars on sub, so now I should be able to turn it up to 0dBFS!" 

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post #25 of 49 Old 12-11-2012, 08:58 AM
 
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Originally Posted by Steve1981 View Post

Your mileage may vary.

And because of this fact, I upped the ante.

There's a story here of lost innocents where a single Klipsch, RW-12d was sufficient to rock one's molars. Now that innocents having been lost, my eyes have been turned as all they see are the big dogs that go "WOOF! WOOF! WOOF!"

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post #26 of 49 Old 12-11-2012, 09:01 AM
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Quote:
Originally Posted by economyte View Post

Quote:
Originally Posted by shadyJ View Post

I don't think a single VTF3 is hitting THX reference unless you are sitting right in front of the woofer or are listening in a closet. You will need a SPL meter to see what kind of output you are getting. Remember you also need low distortion at 115 db, so the sub has to be hitting that clean. There are very few commercial subs that can hit THX reference in a normal room.

Well I am sitting nearfield, but that sounds like it isn't nearly enough.

I guess what I am having difficulty w/ is knowing whether I am getting clean/low distortion output at 115db if I am testing from an SPL meter.

Seems like an expensive way of testing, but is what people do just buy more and bigger subs and just hope they end up getting clean output at reference levels for HT?

Do you know how loud 115db is?
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post #27 of 49 Old 12-11-2012, 09:08 AM
 
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Originally Posted by sputter1 View Post

Do you know how loud 115db is?

According to the chart, pain doesn't start until 125dB.

......................rolleyes.gif

The above comments bring about the question, how loud does one need to go? Will two 15" subs do the job or does one need to hit the hip and get a pair of 18" subs for a 3,500 cuft listening area that opens to a kitchen and entryway? The point, when is loud, loud enough and when is loud just spending money?

By comparison, a pair of 15" Funk Audio 15.0 subs or a pair of Funk Audio, 18.0 C's. I think $800.00 separate the two choices or would I just be going cheap for $800.00. My ego demands the 18" subwoofers. My question is a curiosity question as I'm sure the ego would only be happy with the 18" subs.

-
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post #28 of 49 Old 12-11-2012, 10:26 AM - Thread Starter
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Quote:
Originally Posted by Eyleron View Post

Physics is a bitch.
Accept that reference level bass is really, really, hard. Very few people have it, know about it, can afford it, and can do it right (out of the home theater users). 
It's easier and cheaper nowadays than it was ten years ago, and it'll be even easier ten years from now. I know this is disappointing now, though.

So, you can:
  1. Buy bigger / more subs. 
  2. DIY infinite baffle, plus maybe an in-room sub to smooth response.
  3. Accept that your bottleneck is your sub, and you can only do -5dBFS or -10dBFS. (I'm sure your speakers will still sound more dynamic than mine!)
  4. Compromise on the frequency response: as you turn it up closer to reference, your bass will be more diminished with the respect of the rest of the frequency response. Down 5-10dB at different bass frequencies. Or exhibit more distortion and not sound like it should.

#1 and #2 cost more money. #2 can be cheaper and might be an option if you don't want too many boxes in the room. It depends on your budget and will and skills.

#3 doesn't require more money and isn't a compromise on quality, just the level. Although if your at-seat response isn't smooth yet, you have more placement or EQ work to do. Or need another sub for the smoother response and 3dB of additional output.

 
#4 is something a lot of people, unfortunately, do. They figure "I spent $XXXX dollars on sub, so now I should be able to turn it up to 0dBFS!" 

So since the time of this post, I ended up deciding to just get a larger sub, so I returned the VTF3 and picked up a Submersive. Even though the room is an open concept layout (50 x 25 plus an opening for stairs and a hallway), the Submersive is corner loaded and I am sitting nearfield (within 2 meters of the sub). I was contemplating picking up a second, but over the weekend I watched Dark Knight Rises at -5 (after audyssey calibration) with the subs running 6 decibels hot, and it seemed more than up to the task. Not quite sure if the SPL was lower on any particular bass frequencies though during the airplane or football stadium scene, but I'm happy enough with it right now that I am not too concerned to figure that one out.

As far as the audio being painful because it was too loud, there were only a few moments in the movie that made me wince, but it was otherwise at a fairly comfortable and enjoyable level.
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post #29 of 49 Old 12-11-2012, 10:47 AM
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BTW guys, someone mentioned bass management and needing 123 dBs for reference. THis maybe true but in all the movies I have tested the highest peak measurement I have recorded was 120 dBs coming from FOTP plane crash scene and that was running at reference with the subs calibrated flat. There are others that reach 117-118 dBs(Again running flat).

Nice choice on the submersive and a worthy and major upgraded from your HSU sub. Congrats!

I used to own those Klipsch THX subs and they do or did sound great back then and looking at what the Rhytmik does compared to the pair tells me something is off a little.
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post #30 of 49 Old 12-11-2012, 11:01 AM
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Technically, I'd agree that the 123ish dB number ishould provide complete certainty that you can hit reference no matter what the content, assuming that is flat (or eqed flat) down to at least 20 Hz (lower for may of us) and not compressing at those levels.

I, however, don't listen at reference, and am happy enough if my sub will reach my maxima under real world conditions, which changes things. The part of the change I've really struggled with is, what are the real world max levels (in -dBFS) for 20 Hz. If the content is hitting 115 dB at reference in the LFE, you can be pretty doggone sure it's not 115 dB at 20 Hz, because that would have to be a 20 Hz sine wave, or else it would be digitally clipped.. But is it going to be -10dBFS at 20 Hz, worst case, or even lower? Rolling aroundin the Movies with BASS thread, I've sorta kinda convinced myself that if I listen at -20 or below, even with a likely 10 dB boost at 20 Hz from Audyssey DynEQ, I can probably live with flat, clean, uncompressed at 95 or 97 dB at 20 Hz. But I'm not sure if that assessment's accurate (although I AM sure that my current sub cannot do it . . .)
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