I'm appreciate suggestions or guidance for a enclosure for the Acoustic Elegance TD18H+.
I have the Apollo version in 8 ohms.
It may be because I haven't figured out how to properly use it, but Bass Box Pro 6 is coming up with impossible enclosures of 2 cu. ft. and such.
Goal is an F3 of not higher than 30 Hz, with or, if possible, without EQ.
Larger goal is to cross the AE over around 600 Hz to a B&C DCX462-16 coaxial compression driver, either on a Arai A290 or a B&C M75 horn.
I have the Apollo version in 8 ohms.
It may be because I haven't figured out how to properly use it, but Bass Box Pro 6 is coming up with impossible enclosures of 2 cu. ft. and such.
Goal is an F3 of not higher than 30 Hz, with or, if possible, without EQ.
Larger goal is to cross the AE over around 600 Hz to a B&C DCX462-16 coaxial compression driver, either on a Arai A290 or a B&C M75 horn.
Well, one poster on the AE website reported excellent results with 9.5 cu. ft. tuned to 25 Hz, though I suspect, but cannot confirm, that he was using DSP-based EQ to boost the lowest octaves. I could live with that—if necessary, to meet my objectives—but would be happier with 8 cu. ft.
Hmm, had forgotten what a serious classic prosound BR, bass horn driver it is. Unfortunately its specs dictates a ~Vas/1.44 tuned to 1.56x Fs for max performance, so the poster is near spot on re Vb and unless the room boosts the low end it will need some form of EQ tuned down around Fs and with the low note on a piano is 27.5 Hz it's a good place to tune to or up it to 32 Hz for other instruments.
Available power and/or highest average SPL desired will set the vent dims and the cab Vb can be pretty much what you want it to be since a T/S max flat is only 1.86 ft^3/52.6 L! with the understanding that the vent gets (much) longer with increasing shrinkage.
FWIW, a good compromise is the mean between a proper max flat (Vb = Vas, Fb = Fs) and T/S is (389.24*52.6)^0.5 = ~143 L/5 ft^3 a popular size way back when with these type specs were the norm for Altec, JBL. etc..
Available power and/or highest average SPL desired will set the vent dims and the cab Vb can be pretty much what you want it to be since a T/S max flat is only 1.86 ft^3/52.6 L! with the understanding that the vent gets (much) longer with increasing shrinkage.
FWIW, a good compromise is the mean between a proper max flat (Vb = Vas, Fb = Fs) and T/S is (389.24*52.6)^0.5 = ~143 L/5 ft^3 a popular size way back when with these type specs were the norm for Altec, JBL. etc..
I had the same problem with my AE PB18 H+ (having a dust cap instead of the phase plug as TD18 H+, otherwise the same). -What is suitable box size and F3? I ended up with sealed ones, 174 L prior to stuffing and an F3 around 116 Hz from simulations. Still, in my room the SPL at 10 Hz is actually louder than at 116 Hz. For F3 and box size, you may take in consideration the type of room you have. Is it concrete / brick or or a leaky one with stud walls + gypsum all around? Also, the longest room dimension (can) play a part too.
A post about my decision about box size / F3 with considerations taken to my concrete room: https://www.diyaudio.com/community/threads/active-basstraps.331145/page-3#post-6836275
A post about my decision about box size / F3 with considerations taken to my concrete room: https://www.diyaudio.com/community/threads/active-basstraps.331145/page-3#post-6836275
Thank you GM! Looks like I'll be building a big box tuned low. . .I'd switch to the NOS pair of BMS 18N860 I have in storage, but they're not viable for a 500-600 Hz crossover, which was what I wanted to try. . .
Thank you, too, Adhoc1! My room, I suppose, is rather large: 43 x 26 x 18 feet. Walls are double-layer 5/8" drywall on metal studs with Green Glue acoustic damping compound between the layers and lots of fibreglass and mineral wool insulation behind the drywall.
Thank you, too, Adhoc1! My room, I suppose, is rather large: 43 x 26 x 18 feet. Walls are double-layer 5/8" drywall on metal studs with Green Glue acoustic damping compound between the layers and lots of fibreglass and mineral wool insulation behind the drywall.
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If you want 30 hz i would suggest looking for a different bass driver. Or a really big TL or horn.
I cannot get any decent sims that even get F10 to get anywhere near 30 Hz. Low Qt and an Fs mzke you goal very difficult.
Do note that F3 is meaningless to humans (ref Toole). Look at F6 and F10
dave
I cannot get any decent sims that even get F10 to get anywhere near 30 Hz. Low Qt and an Fs mzke you goal very difficult.
Do note that F3 is meaningless to humans (ref Toole). Look at F6 and F10
dave
Could you say more about F3 being "meaningless to humans"? I have of course heard of Floyd Toole, but no idea where or in what context he made that statement. Thanks! Joel.
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Toole showed that humans cannot perceive F3 (it is usful if you are using it as part of a filter), and that F6 & F10 are much more useful at predicting how low a human listener will perceive the bass.
Also it is important not to ignore any room gain (in a room as large as yours likely only at the lowest frequencies.
As a refernce if i was designing a (monster) miniOnken for this driver it would be in 65 litres and reach an estimated F6 of just under 55 and an F10 just under 50. To go lower i would see if Scott could come up with a TL or horn but i would expect the end volume would be much larger.
dave
Also it is important not to ignore any room gain (in a room as large as yours likely only at the lowest frequencies.
As a refernce if i was designing a (monster) miniOnken for this driver it would be in 65 litres and reach an estimated F6 of just under 55 and an F10 just under 50. To go lower i would see if Scott could come up with a TL or horn but i would expect the end volume would be much larger.
dave
If I can't perceive F3, doesn't that mean it would sound to me as if perfectly flat (F0) at the F3 frequency, and wouldn't that be a good thing?
As for the hypothetical "monster mini-Onken," wouldn't be impossible to design a 65 litre enclosure into which an 18" driver would fit?
Aside from that, for me, at least, there's no reason to build a speaker with an F6 of 55 Hz.
My main speaker system—Meyer Sound Labs X-10T with X-400C subwoofers—measure 2 dB down, in-room, at 23 Hz, so I do have some idea of what to me is an "ideal" LF performance.
The original goal was a speaker system using the B&C DCX462 coaxial compression driver and ME75 horn with a LF driver that would achieve both high overall system sensitivity—say 95 dB—and what is, to me, impeccable LF response for music-only reproduction. If that's not a realistic goal using the TD18H+, it may be more prudent to pass those drivers on to another hobbyist, and look for a more suitable driver. . .
As for the hypothetical "monster mini-Onken," wouldn't be impossible to design a 65 litre enclosure into which an 18" driver would fit?
Aside from that, for me, at least, there's no reason to build a speaker with an F6 of 55 Hz.
My main speaker system—Meyer Sound Labs X-10T with X-400C subwoofers—measure 2 dB down, in-room, at 23 Hz, so I do have some idea of what to me is an "ideal" LF performance.
The original goal was a speaker system using the B&C DCX462 coaxial compression driver and ME75 horn with a LF driver that would achieve both high overall system sensitivity—say 95 dB—and what is, to me, impeccable LF response for music-only reproduction. If that's not a realistic goal using the TD18H+, it may be more prudent to pass those drivers on to another hobbyist, and look for a more suitable driver. . .
Thinking back on what's in the storage room, I also have available:
— a quartet of TAD TL-1601b
— a pair of JBL 2235H (in 5 cu.ft. cabs tuned to 30 Hz)
— a pair of JBL 2234H (2235H without the glued-in mass ring)
— a pair of TAD TL-1801 (in 7 cu.ft. cabs tuned to 32 Hz)
— a quartet of TAD TL-1601b
— a pair of JBL 2235H (in 5 cu.ft. cabs tuned to 30 Hz)
— a pair of JBL 2234H (2235H without the glued-in mass ring)
— a pair of TAD TL-1801 (in 7 cu.ft. cabs tuned to 32 Hz)
Thanks, Dave! (Although the B&C ME75 horn can't support such a low crossover point.)
Go look at TADs own designs etc, the 1601 is traditionally XOed 6-700 hz in the TSM's etc.
Of your listed drivers it's the best suited one for a 600+ XO, while it reaches lower then the TD18.
No experience with the TD18, never saw a measurement either.But it is clearly not suited to deliver a 30hz F3 without active EQ.
The TL-1801 is a nice driver, that will deliver the desired F3, but is best crossed a octave lower then 600 imo.
With such a long rooms as 43 feet / 13,1 m, any possible pressure gain would start below 13 Hz = of no interest for music. II you checked the link in my post, in my room 7,86 m long pressure gain starts to show up clearly sligthly below theoretical 21,5 Hz.
As you have several pair of speakers / subs tuned quite low. I would check out actual rooms modes versus theory and make a guesstimate what room gain you can count on / how lossy the room is versus a simulation result in the speaker program you use. 1 sub on the floor towards the corner and the microphone in the diagonal upper corner to check out actual modes.
@Arez very much can depend on the type of room one has. My AE PB18 H+ reach down to below 10 Hz measured in REW without any EQ. They are sealed with FB about 48 Hz and F3 around 116 Hz. SPL at 10 Hz is about 9 dB louder than at 116 Hz. From simulation it should be down about 29 dB..That huge difference is due to a lot of room and pressure gain.. System215 cannot count on any pressure gain becasuse of his room length, room gain is = ? but lower than in my concrete room and also depends on positioning.
As you have several pair of speakers / subs tuned quite low. I would check out actual rooms modes versus theory and make a guesstimate what room gain you can count on / how lossy the room is versus a simulation result in the speaker program you use. 1 sub on the floor towards the corner and the microphone in the diagonal upper corner to check out actual modes.
@Arez very much can depend on the type of room one has. My AE PB18 H+ reach down to below 10 Hz measured in REW without any EQ. They are sealed with FB about 48 Hz and F3 around 116 Hz. SPL at 10 Hz is about 9 dB louder than at 116 Hz. From simulation it should be down about 29 dB..That huge difference is due to a lot of room and pressure gain.. System215 cannot count on any pressure gain becasuse of his room length, room gain is = ? but lower than in my concrete room and also depends on positioning.
On average, though best to test yourself with an EQ with 3 dB increments to find how loud it must be at different frequencies and better to test any females that will use the system as their hearing is typically (much) keener overall.
You're welcome!
Cool, close to my original 46' x 26' cathedral ceiling audio/video room, though the whole house cost overruns due to a rapid inflation of the times forced me to scrimp on wall construction among other things, but then with a well damped exterior on a corner lot and in our early '20s we really didn't care. 😉 'In-A-Gadda-Da-Vida', etc., at ~rock concert levels of the time was great for 'training' newborns to sleep through most anything loud. 😉
Why, ~521 Hz is a 'natural' point based on the driver's upper mass corner (Fhm = 2*Fs/Qts) and the VC's frequency (~13543"sec/pi/4" = 1077.7 Hz), not to mention the pioneers choosing 500 Hz as it's the 1/2 acoustic power point of a 75 piece orchestra.
Right, my original big room and now not so big, but opens to a larger space one = corner loading a 'must' for any room help.