BOSSOBASS Raptor system 3

[MKtheater]

I am not sure what I get for room gain but the SI's have been measured and I have a rising response where 5-10 is flat but 5 dB higher than 30-200hz.

[MKtheater]

BTW, I have 4 18's 7 feet away and 8 18's 14 feet away and they need the same amp gain settings to reach the same levels.

[3ll3d00d]

One more thing.  My recent reading suggests that the 85 dBC calibration standard should really be treated as "85 dB (nominal)".  Apparently, using the Dolby pink noise signal and measurement equipment with the standard calibration procedure leads to a system that produces closer to 83 dB per channel when using C-weighted -20 dBFS RMS pink noise.  So actually, the 121 dB figure for 5.1 (and 123 dB for 7.1) may be closer to reality for a system calibrated to "85 dB (nominal)" using the standard Dolby tools.

83dB vs 85dB comes from the use of band limited pink noise so the 2dB drop represents the reduced energy put into the room. Band limited is typically 500-2000Hz for mains and 30-80Hz for subs (IIRC). This is intended to enable people with limited tools (i.e. a c weighted spl meter set to slow) to still be able to reasonably accurately calibrate a setup.

 

I can't say how this figure relates to the actual output capability of a subwoofer when driven hard into ULF territory. 

[3ll3d00d]

Random post to back up Dave's comment on very low frequency gain. My data for my current room shows a gain of roughly 5dB at 16Hz, 14dB or so at 10Hz and a massive 28dB at 7Hz. My data for frequencies lower than that is somewhat suspect due to equipment roll off and bad SNR in the outdoor results. 30dB at 5Hz would seem to be about right at least in my room. This is all comparing to 2m ground plane/ 1m anechoic. YMMV

I get ~12dB per octave from ~23-24Hz so I get to the best part of ~25dB by ~7Hz. 

[MKtheater]

I thought It is impossible to get 12 dB per octave as every room will have leaks. Maybe concrete ceilings and doors would do it?

[SME]

83dB vs 85dB comes from the use of band limited pink noise so the 2dB drop represents the reduced energy put into the room. Band limited is typically 500-2000Hz for mains and 30-80Hz for subs (IIRC). This is intended to enable people with limited tools (i.e. a c weighted spl meter set to slow) to still be able to reasonably accurately calibrate a setup.

I have read this argument elsewhere, but it can't be right.  Suppose you start with C-weighted pink noise at -20 dBFS RMS.  This noise is band limited to between 30 Hz and 8000 Hz or so, a range spanning about 8 octaves.  Now band limit that noise to cover only the 500-2000 Hz range, spanning 2 octaves.  Pink noise has equal energy per octave, so you've just cut about 3/4s of the energy, or about 6 dB.

 

The real reason for the discrepancy is much uglier and has to do with technical limitations of older equipment upon which preceding standards were built and the interest in providing interoperability between standards.  There was a controversy over whether to change the standard calibration level to 83 dB to account for differences between modern and legacy equipment or to leave the standard at 85 dB and accept a level disparity between older and newer content.  Ultimately, a bizarre compromise was reached in which adjustments were made to the pink noise source and measurement equipment so that a system calibrated to "85 dB" with the modern equipment still played legacy content at the correct level.  From my reading, I have not found out the full details of these adjustments, and I have seen suggestions that the standardized equipment were a proprietary designs by Dolby.

 

Since then, music mastering engineer Bob Katz created his own standard with more of an aim for the music industry and settled on 83 dB RMS for -20 dBFS RMS C-weighted pink noise, arguing that it is reasonably close to the results of the original 85 dB theatrical standards.  Note that the pink noise is normalized after the C-weighting is applied.  This way, one can also band limit the noise to a smaller range (e.g., 500-2000 Hz), normalized it to -20 dBFS RMS, and it should play at the same level as the C-weighted noise on a flat system.

[SME]

I thought It is impossible to get 12 dB per octave as every room will have leaks. Maybe concrete ceilings and doors would do it?

A perfectly sealed room will achieve 12 dB/octave in the low frequency limit.  However, the limiting behavior does not appear until well below the frequency at which the half wavelength matches the longest room dimension.  A real life room with leaks may leak certain resonant frequencies much more than others even well below the frequency at which the half wavelength matches the longest room dimension.  Such a room can even introduce negative room gain for some frequencies, meaning that it's entirely possible to see > 12 dB/octave change for decreasing frequency in a localized part of the response.

[SME]

Random post to back up Dave's comment on very low frequency gain. My data for my current room shows a gain of roughly 5dB at 16Hz, 14dB or so at 10Hz and a massive 28dB at 7Hz. My data for frequencies lower than that is somewhat suspect due to equipment roll off and bad SNR in the outdoor results. 30dB at 5Hz would seem to be about right at least in my room. This is all comparing to 2m ground plane/ 1m anechoic. YMMV

At 5 Hz, 30 dB is pretty impressive.  How big is your listening room?

[3ll3d00d]

I have read this argument elsewhere, but it can't be right.  Suppose you start with C-weighted pink noise at -20 dBFS RMS.  This noise is band limited to between 30 Hz and 8000 Hz or so, a range spanning about 8 octaves.  Now band limit that noise to cover only the 500-2000 Hz range, spanning 2 octaves.  Pink noise has equal energy per octave, so you've just cut about 3/4s of the energy, or about 6 dB.

AIUI it boils down to the precise way the level of the noise is calibrated. I don't know the details but there's a variety of discussion on the jriver forum on the subject from when they were implementing their tones with Bob Katz's guidance (e.g. http://yabb.jriver.com/interact/index.php?topic=77124.0and http://yabb.jriver.com/interact/index.php?topic=78378.0 ). His site has a wide variety of discussions/articles on the subject as well. You've probably read most of that anyway given the rest of your reply.

 

The specifics seem somewhat by the by to me though. The relevant point is that this is a method used for calibrating a system to a specific reference and requires a specific set of tones that have been created in a certain way in order to be "accurate" (where "accurate" may or may not include some degree of fuzz factor for historic reasons). I don't think it means you can precisely extrapolate the peak SPL demand from your system from this reference calibration routine as this is going to be content specific.

[Ricci]

At 5 Hz, 30 dB is pretty impressive.  How big is your listening room?

 

About 3650cu ft. Cement slab, half submerged basement, 3 brick exterior walls, 2 below ground level.

[Bossobass Dave]

If a room were perfectly sealed, you'd soon die of asphyxiation. IOW, no room is sealed.

 

Boundaries create Sound Wave Interference. These are reflections which are either destructive or constructive. The reflections are progressively more constructive (or, conversely, less destructive) as frequency decreases (wave length increases).

 

Below 10 Hz, a 110 foot wave length, the size of the Home Theater room is irrelevant. What determines the rate of increase in dBSPL per octave as frequency decreases is transmission losses from the boundaries. No room is infinitely rigid so all rooms suffer transmission loss at the boundaries, especially <100 Hz.

 

Underground basement masonry wall construction HTs on a slab have 50 times or better less transmission loss than above ground wood structure/siding/interior walls construction HTs. This is the single reason basement HT owners prefer loud over accurate.

[chrapladm]

Only asking Bosso, but shouldn't people with basement theaters want accurate verse traditional construction HT's?

 

If I didnt need high SPL I would prefer accurate. And it would seem it is much easier to have high SPL in a basement than normal room. Of coarse I want both but just saying. I also would hope for extremely low noise floor but accurate is all I want. I cant afford the SPL game.

[MKtheater]

Bosso means playing the LFE hot is not accurate. So loud is hot and not accurate which is correct. I have concrete all around my basement except the ceiling and I think I get 30 dB gain at 5 hz or close to it.

[Archaea]

Arch,

 

I've had a few minutes since last week to look at this post and I'm wondering if you can provide some details?

 

Do you have a FR of the near field sub? I mean no harm here but a 1x18 near field besting 7x18 far field? Honestly? I'd like to compare the FR you posted to the near field response, per previous discussions here on the subject. It's useful info.

 

Beyond that...

 

How on earth is the Dayton system $3k more than a pair of passive Caps + XLS-5K? Maybe I'm missing something, but weren't the Caps $2k each plus the Crown amp?

 

 

IOW, I have to say that I think you're laying some silly putty here with the cost vs performance claims (1x18 near field bests 7x18" far field, dual ported Caps + Crown XLS-5K = 95% of 8 UM 18s + dual iNuke 6Ks, 6th order roll off at 20 Hz = flat to <7 Hz and putting $3K back in your pocket, etc). You seem to have been saying the exact opposite in posts elsewhere. Nevertheless, actual data says you're exaggerating the ported rig's abilities, at a minimum.

 

An honest comment posted here is appreciated, but your post seems a bit tainted by Cap worship and/or a seriously entrenched position from previous debates on the subject with others. In any case, filling in the blanks would be appreciated, if you see this post and have the data.

 

As to the 1 nearfield vs. 7 front wall.

I mean subjectively preferred --- in my opinion and experience.   In fact with my two big captivators on the front wall I still got very excited about a single 10" Infinity Kappa Perfect directly behind my chair.  Not because of output -- but because of tactile feel.

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1438696-comparison-three-tactile-transducers-buttkicker-mini-lfe-vs-clark-synthesis-tst209-vs-aura-bass-shaker-pro-7.html#post24672956

 

I've since closeted those 10" drivers and that project because I couldn't keep them close enough to the chair to matter when I reclined --- so I moved three of my 18"s behind my primary chairs.

 

Further testing with my sealed 18" and nearfield subs indicated I definitely still preferred the nearfield feel, over loading up the cabs on the front wall.

 

 

Basically it amounts to this - one nearfield 18" subwoofer nearfield has more tactile presence and enjoyment factor firing directly into my back as all the others on the front wall.  I'm not talking about sheer SPL, I'm not talking about perfect frequency response --- I'm just talking about enjoyment and feel.  It's a bit of a conundrum because if you just have one sub directly behind you it works well, and alone could suffice, but if you put 3 subs behind you - like I have now (to allow the primary three seats a good tactile experience) - then you can't only have the three subs on alone because they now sound like they are behind you.  So I have to have the bank of five up front run a smidge louder than the three nearfield to keep the bass presence originating up front.

 

I tried the caps nearfield once at my old house, but never really enjoyed it that much.  Part of the fun of sealed nearfield  (I think) is that you feel the acoustic energy of the driver moving -- so on the deep frequencies - the nearfield sealed cone is moving heavily, but the ported driver is moving less on that same deep frequency - so the feel is less firing into my back.  The cap ports are basically on the floor - so I didn't feel anything from them behind my chair.  Also when cranking the volume to ridiculous levels you hear port artifact noise when the ported sub is immediately next to you, and don't hear that on the sealed --- whereas any noise like that is pretty much masked by other sounds when the ported sub is at the front of the room.  So sealed is my clear preference for nearfield use after trying both.  

 

As another explanation --- I can watch the sealed subs on the front wall pumping for all their worth and barely feel a thing on my concrete slab -- same at popalocks.  His vertical wall of subs were trying to jump out of their boxes and you didn't feel much --- However, sit down right in front of one - or an array of them as he did --- and you feel that driver pumping on the deep frequencies.  It's a pulsing, it's the next best thing to a wooden floor for those of us on a slab. It's quite enjoyable.

 

You can ask carp, scott simionian, gpmbc, d_c, luke camp, dominguez1, beastaudio, gorilla83, or various others about their opinion on nearfield subs.  I don't think my thoughts are that far out of alignment on the matter with any of these guys after reading their posts.  I get that not everybody likes that tactile feel - you maybe one of those that don't.  For those of us that do -- the nearfield driver firing directly into your back - as close as it can possibly be placed - really delivers.

 

I do have a native nearfield non EQ'ed measurement of one of the 18" UM drivers I think.  I'll check when I get home, and if I don't I'll grab one.

 

Here is some thinking out loud posting when I first setup the sealed 18"s and began to compare them to the Captivators.  You can see how at first I wasn't impressed, but when I got the nearfield going things swung heavily to favor the sealed subs.

http://www.avsforum.com/forum/15-general-home-theater-media-game-rooms/1525397-archaea-s-multi-purpose-home-theater-room-9.html

Post 255.

 

I have a good friend who came over back to back visits with the eight sealed and the two Caps before that.  He liked the Caps better.  He doesn't post on audio forums so I can't give you his handle. He said the eight sealed were not as tactile as the two ported.  He, like me, also liked the air movement that that Caps deliver from their ports.  As another example, avsforum member JDontee from Kansas City relayed he thought I might have made a mistake selling the Caps too after his initial visit to hear my sealed setup.  I like the sealed better personally, but only slightly.  Luke Kamp and Carp like the sealed better, and more than slightly.  The reality is - I've had opinions from many people on both sides of the matter that have heard my setup.  It isn't as if the eight sealed are really that much stronger than the pair of caps in real world use.

------------------

 

 

Yes, the eight sealed cost about twice as much as the Captivator pair.

 

The price quote you listed from me was obviously just the drivers at $2k for 8 drivers.  Since that quote I determined I could not utilize just a pair of iNuke DSP 6000 amps for all eight and posted about that publicly on AVSforum.  Anytime I would try to take it to demo volume levels with deep content my two amps would power cycle.  I tried implementing a HPF at different levels below 20hz which reduced the problem, but then came to the conclusion there was no point in having the sealed at all if I was going to use a HPF hack.  So I had to use more power.   I have come to the easily reached conclusion that the SI HT 18" are a better value conscious buy - because you can run eight of them competently off a single $680 CV-5000 amp.  Carp's done it, and Scott Simian has done it.  By comparison, I'm running three of the UM off a single CV-5000 amp nearfield and the drivers can take all the power the amp can give in 3ohm bridged.  So the UM drivers are significantly more expensive than the SI, and they require double the power.  Are they worth it over the SI HT 18?  I don't know --- honestly I doubt it --- I guess we'll find out when Josh posts the measurements soon.

 

--

 

Jeff runs clearance sales from time to time. I caught one of his overstock sales on a pair of pro cabinet captivators in 2011.   I only needed a single Crown XLS-5000 amp to power the Captivator pair, which I bought on a close out sale.  Your $2k per sub figure is way high.  I paid a little over $3k for both, amped.

My eight sealed cabinets cost a little over $600 each when it was all said and done.  600x8 = $4800 - Make it $5K when you throw in my gas for driving to IL on two occasions to pick up the cabs (4 at a time).  I have a Cerwin Vega CV-5000 driving the nearfield there subwoofers at 3 ohm bridged.  I have two iNuke DSP 6000's running four of the front subs - one driver per channel.  I have a iNuke DSP 3000 running the fifth sub up front bridged.

(1) CV-5000 =  $680

(2) iNuke DSP 6000 = $800

(1) iNuke DSP 3000 = 300

= $1800

+ cables

5K + 2K = ~7K

 

You could do it cheaper with DIY cabinets.  That's not what I did.

 

 

So yes - it's was half price for the Captivators for me - and the performance delta does not justify the cost difference for anyone but an absolute enthusiast.

 

I expect there are times when the eight sealed in my typical configuration underperform the pair of Captivators.  For instance, I played Olympus has fallen recently at the request of Luke Kamp on my sealed setup.  I almost always ran the Captivators 6dB hot and could typically take the main listening volume to -3dB or reference without any concern at all on any movie - regardless -- that experience was steadfast at my old place.  The HPF was placed at about 20z with the Mic2200 for the Captivators.  I have my FR charts well documented with the Captivators and a lot of people experienced them in my room.   With my sealed setup I actually tend to run the subs a little bit hotter more in the range of 6-9dB day to day for movie use.  On that particular Olympus monument falling clip at -10dB MLV all my amps were starting to clip on that scene, and we heard the clipping noises out of the system.  We actually started louder than that and had to keep backing down -- ending at -10dB MLV where you could see the clip lights flicker but not hear bad noises.  That's not something I had to worry about with the Captivators, certainly NEVER at -10dB MLV.  I have to boost the sealed subs a lot at the lowest frequencies to get the flat FR - which takes away from my available headroom.  With the Caps I wasn't boosting anything down low.   Admittedly that Olympus has fallen is a special case, and I don't usually encounter clipping until a louder MLV with the sealed -- but that's how it falls out.  

 

Without the nearfield subs applying the tactile effect of the sub 20Hz material - IMO there would be absolutely no reason on my basement slab to pursue sub 15-20hz frequencies - because they are so subtle aside from nearfield use.   Yes I could put a 20Hz HPF on the sealed and probably go much louder than the two Caps --- but what's the point of sealed at that point?  So we are talking real world usage here.

 

I feel confident that my pair of Captivators was the equal to six of my sealed UM-18, at minimum in real world use.  Eight edges it over the top, and sealed nearfield delivers the TKO in overall enjoyment factor for me.

 

A couple ported Captivators up front, with my sealed nearfield might actually be preferable to what I currently am using.  I sure do miss the air swirling effect!  Though cosmetically I like the look of my sealed cabs better than the Captivators.  The nice veneered cabinets and UM driver look sharp, and I like the five subs up front looking back at me.

 

If I were to go back to ported, ideally, I would want the front ported subs to be natively tuned to 15hz instead of 20hz though, as I think there is strong value found in frequencies between 15z and 20hz, and when I played the JTR Captivators (mine were 20hz native tune) in the 15hz tune (one port plugged), they were underported and I would encounter audible port chuffing when played back at loud volume levels - so I normally used them day to day in 20hz tune -- only putting in the port plug when I didn't plan to go loud and wanted to watch a movie like Gravity which made strong use of the 15hz content.

 

 

I'd be happy to capture any FR of my sealed you want with my omnimic.  I have nothing to hide on that front.

[Bossobass Dave]

Arch,

 

Thanks for the reply. Some comments:

 

So, the ported sub consisted of closeout specials and the sealed sub is new model and custom cabs. That explains your specific situation, but not an actual price difference.

 

I'll just say that there is never a time when a pair of 20 Hz tuned ported 18s outperforms 8-18s sealed. If you reach that conclusion, subjectively or through actual data, you have a configuration/setup problem, period, like the boost/clipping problems you have mentioned.

 

Curiously, to scratch a playback level itch, you don't have a problem changing the preferred 15 Hz tune to 20 Hz tune plus a HPF on the ported rig but inserting a 20 Hz HPF with your sealed system is somehow illegal blasphemy. And, if you did, there's no probably about exceeding playback levels by 10 times over the ported rig.

 

 

I imagine the OHF scene with 20 Hz ported subs was preferred with the Caps because it's centered at the ported rig's tune. There's really not much content below that. What I call ULF undertow.

 

As I've mentioned here and elsewhere, I don't have a preference for a particular distortion. I prefer a flat response at reference level. You have around 40L of displacement. That's good for reference with a few dB of headroom, not 9dB of headroom, as your clip lights have let you know. I would suggest the next level. Four of Nick's HS-24s driven by 2-A-14K amplifiers will provide 60L plus displacement driven by real amplification. That's in the $9-10K arena, but will afford 10dB of headroom to 5 Hz.

 

Nearfield, IMHO, is a fad. Listening and feeling sound are 2 distinct pleasures. Although, if I did have that urge for disproportionately more tactile sensation, I would rather attain it from a pressure wave than from vibration conduction. I suspect that few have properly set up such a system and the FR suffers in the best of worlds. Decades ago, when I was in a rock band, there would invariably be the drunk guy who walked up to the PA stack and stuck his torso into one of the bass bins. I'm sure it was a unique experience but had nothing to do with sound fidelity. I never disparaged the act, but it did make me LOL.

 

I appreciate the details and the measured response of the near filed subs alone, the far field subs alone and the combined response, all at the LP, would be great input.

[SME]

If a room were perfectly sealed, you'd soon die of asphyxiation. IOW, no room is sealed.

 

Boundaries create Sound Wave Interference. These are reflections which are either destructive or constructive. The reflections are progressively more constructive (or, conversely, less destructive) as frequency decreases (wave length increases).

 

Below 10 Hz, a 110 foot wave length, the size of the Home Theater room is irrelevant. What determines the rate of increase in dBSPL per octave as frequency decreases is transmission losses from the boundaries. No room is infinitely rigid so all rooms suffer transmission loss at the boundaries, especially <100 Hz.

 

Underground basement masonry wall construction HTs on a slab have 50 times or better less transmission loss than above ground wood structure/siding/interior walls construction HTs. This is the single reason basement HT owners prefer loud over accurate.

I beg to differ on the point that room size doesn't matter at the lowest frequencies.  Transmission loss (TL) is certainly important, but unless the TL is very high, size matters too.  The bigger the room, the more air that needs to be added/removed by the sub to create the same SPL.  Those seeing close to 12 dB/octave room gain have low TL and a room that is nearly sealed so that TL can be largely neglected.  Assuming the room pressurization involves negligible energy transfer from the air to the boundaries, one can expect an SPL change of about -14*log10(V2/V1) in the limit of low frequency, where V1 and V2 are the "before" and "after" volumes.  This translates to an approximate 4 dB overall drop per doubling of room volume.  With non-negligible TL, the relationship is more complicated and depends on the distribution of high TL surfaces in the space.

 

Also, for very low frequencies in real rooms, there may be structural resonances present well below 10 Hz in which TL is very high and dips appear in the response despite low TL for much of the rest of the range.

[SME]

About 3650cu ft. Cement slab, half submerged basement, 3 brick exterior walls, 2 below ground level.

Assuming your 3650 cuft space has surfaces with similar TL as my 20k cuft space (the approximate total volume of my house + garage + basement, enclosed by concrete and brick construction) and assuming both of these spaces have low enough TL to neglect, my formula suggests I will see about 20 dB room gain at 5 Hz.  There's still hope!  With CEA a 10 Hz CEA limit of ~95 dB at 10 Hz for an HST-18 driver and assuming -12 dB or ~83 dB going from 10 to 5 Hz, I can still achieve 115 dB at 5 Hz in-room with four of those woofers.  I still need 8 to do it "cleanly", but with most content down low being < 105 dB, I'm probably fine.

 

Of course all this is based on some pretty rough estimation since we may still have very different TL, and I do have some interior walls and flooring between my house space (9k cuft) and my garage and basement.  I think I also sit closer to my subs (about 3m).  Hopefully this means my estimate is on the low side as far as output is concerned.

[BeastAudio]

Bosso,

 

I am relatively confident that given the right parameters set forth by you, I could have my nearfield sub calibrated perfectly to enjoy the full force of the 8 sealed you have already experienced, in all their glory, while at the same time, just adding that little amount of tactile sensation that I am missing with being on a slab. I have messed with the EQ, delays, and levels extensively for several months now and while at moment I have the nearfield at a "Flat" response with the rest of the FR, the front subs are still a good 7-10dB (depending) hotter than everything else. Both setups are rocking LT's now and the response suffers in no way by adding in the nearfield. 

 

At this given time, I am still having fun with the setup tuned this way. The wife, not so much, so when we watch movies together I cut the nearfield about 6dB more and the effect is very subtle, but still there and still adds just that last little bit to the experience..

[Bossobass Dave]

I beg to differ on the point that room size doesn't matter at the lowest frequencies.  Transmission loss (TL) is certainly important, but unless the TL is very high, size matters too.  The bigger the room, the more air that needs to be added/removed by the sub to create the same SPL.  Those seeing close to 12 dB/octave room gain have low TL and a room that is nearly sealed so that TL can be largely neglected.  Assuming the room pressurization involves negligible energy transfer from the air to the boundaries, one can expect an SPL change of about -14*log10(V2/V1) in the limit of low frequency, where V1 and V2 are the "before" and "after" volumes.  This translates to an approximate 4 dB overall drop per doubling of room volume.  With non-negligible TL, the relationship is more complicated and depends on the distribution of high TL surfaces in the space.

 

Also, for very low frequencies in real rooms, there may be structural resonances present well below 10 Hz in which TL is very high and dips appear in the response despite low TL for much of the rest of the range.

 

Subwoofers do not pressurize a room. They create a pressure wave in the room. Ambient pressure is unaffected.

 

Exciting a resonance never results in a decrease in amplitude. It always results in an increase in amplitude.

 

Several of us have shown that opening doors and/or windows actually increases ULF in dBSPL, to dispel the myth that a sealed room offers higher output at any frequency.

 

These rooms var from 1600 cubes to over 6000 cubes:

 

 

They are (+/-) 2.5dB.

[Bossobass Dave]

Bosso,

 

I am relatively confident that given the right parameters set forth by you, I could have my nearfield sub calibrated perfectly to enjoy the full force of the 8 sealed you have already experienced, in all their glory, while at the same time, just adding that little amount of tactile sensation that I am missing with being on a slab. I have messed with the EQ, delays, and levels extensively for several months now and while at moment I have the nearfield at a "Flat" response with the rest of the FR, the front subs are still a good 7-10dB (depending) hotter than everything else. Both setups are rocking LT's now and the response suffers in no way by adding in the nearfield. 

 

At this given time, I am still having fun with the setup tuned this way. The wife, not so much, so when we watch movies together I cut the nearfield about 6dB more and the effect is very subtle, but still there and still adds just that last little bit to the experience..

 

 

I appreciate the vote of confidence, it means a lot coming from you, Beast. But, I have to say that near field placement just didn't work for me.

[Luke Kamp]

I appreciate the vote of confidence, it means a lot coming from you, Beast. But, I have to say that near field placement just didn't work for me.

While we have industry standards for level, bandwidth... there is none I can find about feel. So all we have are opinions. On one side of the spectrum you have someone like Paul Hales check out 53:45 on for a few minutes.

http://www.avsforum.com/forum/138-avs-forum-podcasts/1478854-science-room-paul-hales.html

 

He even talks about source material vs. steady state signals. I think this is something you would like and agree with what he has to say Dave. 

 

Then on the other side of the spectrum you have someone like Dr. Hsu who uses one of his mbm's right behind him crossed over to another sub ~ 50hz. 

 

So I say people should Edison it up and try different setups to find out what they like for their system.

 

Archaea another thing is your enclosures are too small IMO for your drivers. The UM's just don't have the motor and the clean power handling of the LMS's. Larger enlosures would increase efficiency down low and you wouldn't need as much boost or worry of power compression. 

[Infrasonic]

Agreed. I suggested that his next move (in subwoofers) would be to manifold mount them all up front in an IB system to gain a great deal of low end sensitivity.

[MKtheater]

Scott, it works awesome assuming the driver works for the IB. I don't use much power at all and so I am driver limited from having enormous enclosures. I don't need boost down low and actually use less power at 10hz than 30hz thanks to my room.

[Infrasonic]

They would work great. I would not suggest it if not.

 

 

But anyway.... BOSSO THREAD! Where's Adam?

[lukeamdman]

You guys with all that room gain make me jealous.  What's makes me even more jealous is Dave's floor that resonates at ~7hz.  

 

What Josh tested to ~102db at 10hz outdoors at 2 meters with only makes it to 106db at 10hz in my room.  A whopping 4db of room gain...super lame.