Just finished building 4 of the 8 subwoofers and did some quick measurements.No 130dB indeed is way too much. I'm already very happy with 115dB (THX reference level) I Just simulated LLT's (300L per driver and 11Hz tuning) with all 18's and 21's with amplifier power matched to their excursion limit and got these numbers:
1. Front sub = 4x Faital Pro 18XL1800 LLT: 10Hz = 118dB / 20Hz = 122dB
2. Right rear sub = 2x B&C 21SW152/8 LLT: 10Hz = 113dB / 20Hz = 117dB
3. Left rear sub = 2x SBA NERO-21SW1100D LLT: 10Hz = 109dB / 20Hz = 115dB
4a. Optional center rear sub = 4x Visaton TIW400 sealed: 10Hz = 98dB / 20Hz = 110dB
4b. Optional center rear sub = 4x Visaton TIW400 LLT: 10Hz = 107dB / 20Hz = 113dB (2x woofers in 300L instead of 1x)
This should sound very impressive with ART (and without destroying the structure of the house). So 8x sealed 21"+ 8x 21" LLT will give scary amounts of LFE
I just saw Rebel Moon on Netflix. I was barely able to watch till the end but the Atmos soundtrack sounded very powerful with lots of 20-30Hz content.
I just did a quick EQ import from REW into my Storm Audio and managed decent EQ'd results. Blue is no EQ and the other with EQ.
I did not boost the low end so in my room atleast these 4 x 21" Nero subwoofers are flat down to around 15hz.
I did a 20hz THD test at around 110dB, was pretty intense already at this level and it sounded very clean, no wierd mechanical sounds etc.
Everything running off an Inuke 6000DSP for the time being. Woofers in parallel in pairs.
Please don't mind the mess, it's a workshop right now
Organ is of course the unignorable instrument for low notes, which Richard Strauss used to good effect in Also Sprach Zarathustra. The song begins with a C0 (16 Hz), sustained for almost a minute. When it lets up the room depressurises and opens up the space for the trumpet fanfare, then the final tutti chord reiterates the C0 with a few more dB added. It's pretty ripping.
Time Warp (Telarc) has this and a few others, including the Star Trek movie theme which begins with a massive kettledrum hit. That'll launch a few cones across the room.
Not really as it requires a MiniDSP 2x4HD. I want to keep all room correction and filtering inside my AVR to get the best possible sound.
Very nice results both for the build and the measurements!Just finished building 4 of the 8 subwoofers and did some quick measurements.
I just did a quick EQ import from REW into my Storm Audio and managed decent EQ'd results. Blue is no EQ and the other with EQ.
I did not boost the low end so in my room atleast these 4 x 21" Nero subwoofers are flat down to around 15hz.
I did a 20hz THD test at around 110dB, was pretty intense already at this level and it sounded very clean, no wierd mechanical sounds etc.
Everything running off an Inuke 6000DSP for the time being. Woofers in parallel in pairs.
Please don't mind the mess, it's a workshop right now
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4 of them can do 118dB @ 20Hz before over-excursion. 8 subs can do 124dB so I'm curious to hear about their combined output when all of the subs are ready. Also nice to see that they do 15Hz in room
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The new Peter Gabriel album I/O has some great infrasonic content in it. Not common for modern recordings to have this nowadays. They usually over spit-shine everything and try to make it sound aesthetically pleasing. Back in the day quite a few recordings were known as woofer killers. If you play an original CD version of Bad from Michael Jackson loud, you'll see the woofers slowly move in and out a bit from the < 4 hz artifacts left over from the kick drum compression. Alot of Columbia / Sony albums had infrasonic junk in them. I was playing a remastered CD copy of Thrust by Herbie Hancock and was surprised to see the woofers being dragged back and forth about 1/2 inch in the beginning of the first track played at roughly 100 dB.
I agree the room plays such an important part, that even the best subwoofer will perform poor if placement is bad and decay is not managed.
I am using a Storm Audio SSP running DIRAC/ART and I am very confident that decay will be managed. I haven't tested with the new 21's yet, but I will calibrate soon. Current subs are handled very well with DIRAC/ART and hopefully the new 21" will make the system perform even better.
I build 8 cabinets, but the remaining 4 woofers are not arriving until feb. 23. So in total there will be 8 x 21" on the frontwall behind the screen.
To be able to fit the LCR's, and possibly larger LCR's in the future I planned on stacking subs on top of each other. I used REW room sim to predict the respons with 8 subwoofers stacked on the frontwall and in practice it seems very promising. So imagine the 4 in the picture with 4 stacked on top of them as the end result.
Combined acoustical power including my 10 x 12" rear subs + 8 x 21" in front should be 120dB@20hz with low distortion and I think that will be enough. Already at ~ 110dB@20hz it was fairly intensive! In theory adding another 4 would be 6dB, in practice maybe less, but with the rear subwoofers included I will hit 120dB@20hz with less then 5% THD I hope. Once everything is installed I hope to make more measurements before running DIRAC/ART, to confirm everything is performing as expected.
I am especially pleased that no forced lift of the low bas is needed on the 21". In room response is nearly flat down to below 20hz. I did anticipate this with room gain for my specific room dimensions, and theory turned out to be quite true in practice.
Huh.
That justifies the 16 Hz highpass in my design, which really wants a HPF since it comprises vented subs corrected with a Linkwitz Transform. It's raving insanity, truly a pain in the neck to get right, but it works well once the filter is sorted. I use a highpass at a frequency of about 90% Fb and a Q of 1.0, which gently emphasizes the octave above rolloff and lets me use a LT with a higher Fp and lower Qp to get the same response, with the added advantage of keeping voice coils in the driver instead of decorating the room.
Impressive work you've done there! I'd love to hear the final result
Which LCR and surround speakers do you have?
LCR's are Dali S-280's.
Surrounds 4 x Dali S-180's.
8 Atmos + 1 VOG - Dali - E-80's.
I am looking into other options for LCR's, but I am somewhat limited with a ~40cm/15.75" depth behind the screen. I've compiled a small list of alternatives. I am looking for something that can play loud and I have plenty of space width and height, just not depth.
I am considering building some of my own LCR's instead of the candidates on the list.
Surrounds 4 x Dali S-180's.
8 Atmos + 1 VOG - Dali - E-80's.
I am looking into other options for LCR's, but I am somewhat limited with a ~40cm/15.75" depth behind the screen. I've compiled a small list of alternatives. I am looking for something that can play loud and I have plenty of space width and height, just not depth.
I am considering building some of my own LCR's instead of the candidates on the list.
I like the insanity of your build as I like ported subs too. After all my bedroom AV system has 2x RCF LF18N405 with 14mm X-max in a 13Hz/450L LLT. With certain movie clips I see the woofer doing high excursions above tuning. Right at the tuning frequency the woofer barely moves and under tuning cone movement goes crazy again just as expected without a HPF. Luckily the suspension keeps the woofer in check befor things get nasty.
With the above experience and after much reading on all major fora I'll stay with sealed subs in my living room. I did many simulations in WinISD with low large tuned ported subwoofers and despite their 12dB sensitivity boost around the desired 10-11Hz tuning looks tempting, I'd have to construct a 1000L box per woofer to be able to use a large enough port with the first resonance frequency high enough to fall outside the passband. I want all of them to be capable of producing a clean and tight 15-150Hz for Dirac Art. Their Qtc will be around 0.6 to get the best balance between excursion and power limitation.
I like Dali and have considered the S-280 too but I disliked the low sensitivity and the passive radiators.
The Procella P880 look exactly like what I have in mind for my own HT. I already bought the speakers (Kartesian CD, dual Purifi PTT6.5 and dual PHL 15" woofers to get a 96dB sensitivity) I'm still doubting to go active or passive. Once done, passive crossovers will last very long. OTOH the coils for the passive 300Hz crossover between PHL and Purifi would be quite expensive. With an active plate amp like the Hypex Fusion it's easier and faster to get a decent sounding speaker. OTOH active amps can fail and I would be the only member of the family with the knowledge to replace and repair them. Choices...
I just did a simulation with the PTT6.5M08-NFA-01 in WinISD and if I feed 2 woofers in parallel the maximum 400W, X-max is exceeded just under 165Hz. With that 400W they produce 118dB/1m from 200Hz up and that's where I will cross them over to the dual 15". Dual 8" mids or a single 10" PA style woofer would easily exceed 120dB/1m but would I need that with a listening distance of 5 meter? The Purifi will undoubtedly sound more refined for day to day mixed AV - stereo listening.
That should be enough SPL output for those frequency ranges, even at spirited playback levels
This test is interesting, it's an excellent midrange for sure.
https://hificompass.com/en/reviews/purifi-ptt65m08-nfa-01a-65-true-midrange
What 15" PHL woofers did you buy? Are you going ported with the 15"?
The CD sits in some horn? Tried to search for it, couldnt exactly find the CD you mentioned.
This test is interesting, it's an excellent midrange for sure.
https://hificompass.com/en/reviews/purifi-ptt65m08-nfa-01a-65-true-midrange
What 15" PHL woofers did you buy? Are you going ported with the 15"?
The CD sits in some horn? Tried to search for it, couldnt exactly find the CD you mentioned.
Agreed on SPL. We don't want to lose our hearing. I know all too many people with hearing aids including my own wife.
Yes that's indeed a very good review together with this one: https://audioxpress.com/article/test-bench-the-ptt6-5m08-nfa-01-6-5-midrange-from-purifi-audio
I bought the PHL 6201MNd. It should behave very well with a good x-max, high BL and a low moving mass and inductance. But I urgently need to build test boxes to get an idea of their sound.
The CD is the Kartesian Cmp45_vTLHP which would be used from 2000-3000Hz. The (temporary?) horn is the RCF H100. If the CD+horn sounds disappointing I'll use a high-end dome with waveguide instead.
Crossover points would be 200-300 Hz and 2000-3000 Hz to direct the most important FR to one speaker and keep a good directivity.
Edit: I'll use only sealed enclosures for this project.
Yes that's indeed a very good review together with this one: https://audioxpress.com/article/test-bench-the-ptt6-5m08-nfa-01-6-5-midrange-from-purifi-audio
I bought the PHL 6201MNd. It should behave very well with a good x-max, high BL and a low moving mass and inductance. But I urgently need to build test boxes to get an idea of their sound.
The CD is the Kartesian Cmp45_vTLHP which would be used from 2000-3000Hz. The (temporary?) horn is the RCF H100. If the CD+horn sounds disappointing I'll use a high-end dome with waveguide instead.
Crossover points would be 200-300 Hz and 2000-3000 Hz to direct the most important FR to one speaker and keep a good directivity.
Edit: I'll use only sealed enclosures for this project.
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Did you check excursion with a highpass filter in place? The result could be interesting.
Also, a Linkwitz Transform with Fp at around 70 Hz and Qp about 0.75 won't do much in your passband, however it will work wonders for the phase response at your crossover point.