In the meantime I did some REW RTA measurements @11Hz on both my subs and this was quite revealing. The older sealed 4x 15" Visaton TIW400 clearly distort when pushed a bit harder. See attached picture. Also the port noise on the B&C 21SW152 LLT was quite obvious also @11Hz but the harmonics were quite a bit lower what IMHO explains that they can't be localized despite they're close to the listening position.
So I decided to go all sealed subs with a QTC between 0.5-0.6. For extra headroom and less distortion I bought 2 additional SBAudience NERO21SW1100D and I'm currently building a heavily braced 407L/14cuft sealed enclosure. The B&C 21SW152 will also be converted to sealed with about the same QTC. All 4 will get a slight boost to get the desired infrasonic reproduction.
So I decided to go all sealed subs with a QTC between 0.5-0.6. For extra headroom and less distortion I bought 2 additional SBAudience NERO21SW1100D and I'm currently building a heavily braced 407L/14cuft sealed enclosure. The B&C 21SW152 will also be converted to sealed with about the same QTC. All 4 will get a slight boost to get the desired infrasonic reproduction.
Attachments
Picture perfect and I'd really love to audition that DBA system!
Today I'm going to finish the cabinets for the dual 21" with 12mm black MDF. The cabinet consists of 18mm +12mm plywood glued together so with the 12mm MDF I'll end up with a 42mm thick enclosure. See attached picture.
The bracing was done without CNC and it took a lot of time to get it exactly right but it fits millimetre tight. I also detest glue dripping and running all over the inside panels so they're meticulously cleaned with a putty knife and a wet cloth.
Today I'm going to finish the cabinets for the dual 21" with 12mm black MDF. The cabinet consists of 18mm +12mm plywood glued together so with the 12mm MDF I'll end up with a 42mm thick enclosure. See attached picture.
The bracing was done without CNC and it took a lot of time to get it exactly right but it fits millimetre tight. I also detest glue dripping and running all over the inside panels so they're meticulously cleaned with a putty knife and a wet cloth.
The dual SBAudience NERO21SW1100D sub was finished yesterday although I couldn't prevent some minor cosmetic damage. The performance is 100% within expectation = very tight deep bass. Sitting on top (that place is now taken by the B&C 21SW152 that are waiting for their smaller enclosures) and despite the massive weight and panel thickness you still feel the displacement force when playing infrasonic bass. A dual opposed construction would have solved that but in my room this is not an option. After the B&C are mounted again, I'll take new RTA measurements.
Update: A few weeks ago I bought the Denon AVC-A1H with it's 4 subwoofer outputs. These 4 outputs feed 3x Crown XLS:
One XLS1002PA in bridge mode for the new dual SBAudience NERO21SW1100D/8.
One XLS2502PA in bridge mode for the dual B&C 21SW152/8.
One XLS2502PA in stereo mode for the 4x Visaton TIW400/8.
First room calibration with the standard Audyssey gave good results although the infrasonics that I used to feel with the LLT B&C were not there. I gave the MultEQ app a try but this didn't bring substantial improvements. Up to the next step then.
After ordering and receiving the Audyssey ACM1-X calibrated microphone I downloaded Audyssey MultEQ-X and bought the license. The calibration went smooth with an extension just below 18Hz in my room what confirmed my earlier observations.
For the extra infrasonic push I added a peaking filter to the subwoofers. For now I've settled with a PEQ @12Hz with a Q=3 and a 10dB boost. This falls just outside room mode territory and avoids too much boost under 10Hz.
So far I like what I'm hearing. Stress tests with higher SPL levels show no audible distortion. When I have more time I'll do some measurements in REW so I can do more fine tuning
One XLS1002PA in bridge mode for the new dual SBAudience NERO21SW1100D/8.
One XLS2502PA in bridge mode for the dual B&C 21SW152/8.
One XLS2502PA in stereo mode for the 4x Visaton TIW400/8.
First room calibration with the standard Audyssey gave good results although the infrasonics that I used to feel with the LLT B&C were not there. I gave the MultEQ app a try but this didn't bring substantial improvements. Up to the next step then.
After ordering and receiving the Audyssey ACM1-X calibrated microphone I downloaded Audyssey MultEQ-X and bought the license. The calibration went smooth with an extension just below 18Hz in my room what confirmed my earlier observations.
For the extra infrasonic push I added a peaking filter to the subwoofers. For now I've settled with a PEQ @12Hz with a Q=3 and a 10dB boost. This falls just outside room mode territory and avoids too much boost under 10Hz.
So far I like what I'm hearing. Stress tests with higher SPL levels show no audible distortion. When I have more time I'll do some measurements in REW so I can do more fine tuning
Lowest pedal note on a pipe organ is given as 16.4Hz, four octaves below middle C. That said, I once did some tests with a signal generator and some open-ear style headphones. Tried progressively lower and lower swept frequency tones down to about 5Hz. Below that frequency the sound kind of went away. Didn't investigate whether it was the reproduction system or me that was the limit.
Putting a single NERO21SW1100D in a 95L enclosure (QTC=0.707) will give you a sensitivity of 75dB/1W/1m @20hz so if you feed the driver it's maximum 1100W you'll get 105dB/1m.
For my project I used 2x NERO21SW1100D in parallel in a 407L enclosure (QTC=0.558). This way I get a 85dB/1W/1m sensitivity @20hz.
I would always aim for half the low end cutoff frequency of the lowest note you want to reproduce. In the case of 30hz, Id like to see 15hz F3. You can absolutely hear 15hz as a tone given sufficient amplitude and room dimensions. My LF hearing ability improved with age as opposed to HF hearing, which is done at about 14k these days. I can play 10hz on my HT subs (2 x B&C 18PZB100 in 400 liters aperiodic venting) running from a pair of SP700 plate amps. I've broken a window frame in my living room from too much LF watching a Sinple Minds concert - lol. Wife wasn't happy about this when we got the bill for it.
Thats very interesting. I live 20 min from MIM and need to check that out.Test music for you
An instrument that makes the notes you can't hear
16 Hz
I think there's 2 sides to the argument, being one side prefers flat extension without any perceived coloration of the low end and preserving this linearity enables more faithful reproduction of details in the low end.
I dislike resonances of any kind in the extreme LF and having flat extended response allows better intelligibility of musical events. Most people are so obsessed with exaggerated LF that they don't know what in reality its supposed to sound like.
Thats one of the reasons why car audio is so hard to do, because by inherent nature you need to boost the extreme LF.to overcome road noise. The other issue is how hard it is to perceive extreme LF thanks to its non linear nature and therfore it needs to be exaggerated to be conveyed effectively.
Classical music has alot of infrasonic content and this can be heard very easily when you suddenly don't have it. Listening to pipe organ or piano music shows this pretty quickly and a lack of extreme LF in this type of music becomes quickly evident and disappointing. Linearity is all about perceived spectral balance across the whole range of music. Its very important to have another octave of extension past 40hz if you want to hear all of the music clearly. Try using a subsonic filter @30Hz, even with a shallow rolloff slope and see what it does to a piano track. It ruins the whole balance of music.
I dislike resonances of any kind in the extreme LF and having flat extended response allows better intelligibility of musical events. Most people are so obsessed with exaggerated LF that they don't know what in reality its supposed to sound like.
Thats one of the reasons why car audio is so hard to do, because by inherent nature you need to boost the extreme LF.to overcome road noise. The other issue is how hard it is to perceive extreme LF thanks to its non linear nature and therfore it needs to be exaggerated to be conveyed effectively.
Classical music has alot of infrasonic content and this can be heard very easily when you suddenly don't have it. Listening to pipe organ or piano music shows this pretty quickly and a lack of extreme LF in this type of music becomes quickly evident and disappointing. Linearity is all about perceived spectral balance across the whole range of music. Its very important to have another octave of extension past 40hz if you want to hear all of the music clearly. Try using a subsonic filter @30Hz, even with a shallow rolloff slope and see what it does to a piano track. It ruins the whole balance of music.
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Looks awesome!The dual SBAudience NERO21SW1100D sub was finished yesterday although I couldn't prevent some minor cosmetic damage. The performance is 100% within expectation = very tight deep bass. Sitting on top (that place is now taken by the B&C 21SW152 that are waiting for their smaller enclosures) and despite the massive weight and panel thickness you still feel the displacement force when playing infrasonic bass. A dual opposed construction would have solved that but in my room this is not an option. After the B&C are mounted again, I'll take new RTA measurements.
How's the bass in sealed compared to the ported?
Also how are the SBA woofers holding up against the b&c?
Considering a similar build with 4 sealed SBA21nero behind my screen.
Thanks very much
Below the 21" family photo:
If I didn't already have the B&C 21SW152 I'd probably build an all SB Audience NERO-21SW1100D subwoofer array. The B&C almost cost double compared to the SBA and I don't really need it's extreme power handling for my home theatre.
I'm running my sealed subs without crossovers on the Crown XLS amps. All the correction is done in my Denon AVC-A1H what results in a very natural sounding subwoofer output. The only limitation is that Audyssey MultEQ-X doesn't do much under 20Hz so LFE extension drops off significantly under 17Hz. I'm still thinking of going ported @15hz for this exact reason.
Below the 21" family photo:
If I didn't already have the B&C 21SW152 I'd probably build an all SB Audience NERO-21SW1100D subwoofer array. The B&C almost cost double compared to the SBA and I don't really need it's extreme power handling for my home theatre.
I'm running my sealed subs without crossovers on the Crown XLS amps. All the correction is done in my Denon AVC-A1H what results in a very natural sounding subwoofer output. The only limitation is that Audyssey MultEQ-X doesn't do much under 20Hz so LFE extension drops off significantly under 17Hz. I'm still thinking of going ported @15hz for this exact reason.
You ended up around 200 liter volume right? Just modelled 150, 200, 250 and 300 liters. 200 liters looks like a good compromise for extension and efficiency.
With 4 sealed Nero21SW's in 200 liter cabinets I am modelling around 118dB@20hz and around 114dB@15hz.
Are the subs punchy sounding? I haven't tried a pro driver in my theater yet but for my new screen I just installed I need new subs so was considering something like this.
With 4 sealed Nero21SW's in 200 liter cabinets I am modelling around 118dB@20hz and around 114dB@15hz.
Are the subs punchy sounding? I haven't tried a pro driver in my theater yet but for my new screen I just installed I need new subs so was considering something like this.
My enclosures indeed are little over 200L. The efficiency indeed goes up compared to smaller enclosures but according to WinISD maximum power handling drops rapidly under 40Hz. If you want to run them full power down to 15Hz the enclosure shouldn't be larger than 100L.
Punchy depends on a lot of things but yes they are very capable
Punchy depends on a lot of things but yes they are very capable
I think that you have all needed for infrasonic sounds... No worry !
I have no home-theater at home, only music listening, in a dedicated room. For infra-bass extension, I built my Omega Ripole subwoofer :
It is a compact unit, able to reach 15Hz in a 400x400x440mm package. I use it below 40Hz, under the natural extension of my speakers.
This is perfect for EM of any kind - notably Space Ambient - where there is deep infra-bass content. The Ripole principe generates that floating bass, without any boxy tone of focused resonance... But OK, for explosions, gun noises, crashes and all other huge-boomy noises common in Home Theater, it may not be the best solution !
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