Again, using the T/S max flat alignment math I've posted & 2*Qts to approximate inductance, thermal power distortion:
Vented net volume (Vb) (L) = 20*22.3*.64^3.3 = 102.3 L
Vented box tuning (Fb) (Hz) = 0.42*38.47*0.64^-0.96 = ~24.8 Hz
F3 (Hz) = Fs*0.28*0.64^-1.4 = 20.12 Hz actually F6
Fhm = 2*38.47/0.64 = 120.22 Hz driver offset
~24.8 Hz/102.3 L TP >115 dB/~22-90 Hz/2pi/200 W
~24.8 Hz/102.3 L TH >115 dB/~22-165 Hz/2pi/600 W
Trade-off of course is a 3.46:1 CR, so would have to experiment to find if these Xmax limited sims are reasonable, but 'fast' transients will in theory be OK @ 1.0 kW.
Regardless, these are just to give some reliable math examples to adapt/expand WRT Fb, Fhm, net Vb.
Identical tapped pipe (TP), tapped horn (TH), but notice the TP must be longer by exactly its Fhm offset for a given Fb.
Vented net volume (Vb) (L) = 20*22.3*.64^3.3 = 102.3 L
Vented box tuning (Fb) (Hz) = 0.42*38.47*0.64^-0.96 = ~24.8 Hz
F3 (Hz) = Fs*0.28*0.64^-1.4 = 20.12 Hz actually F6
Fhm = 2*38.47/0.64 = 120.22 Hz driver offset
~24.8 Hz/102.3 L TP >115 dB/~22-90 Hz/2pi/200 W
~24.8 Hz/102.3 L TH >115 dB/~22-165 Hz/2pi/600 W
Trade-off of course is a 3.46:1 CR, so would have to experiment to find if these Xmax limited sims are reasonable, but 'fast' transients will in theory be OK @ 1.0 kW.
Regardless, these are just to give some reliable math examples to adapt/expand WRT Fb, Fhm, net Vb.
Identical tapped pipe (TP), tapped horn (TH), but notice the TP must be longer by exactly its Fhm offset for a given Fb.
Yeah, I was an impressionable 10 when I helped my then neighbor build his to supplement his Karlson K15 kit co-ax 'FR' speaker I also helped with. The cab ultimately was turned into a storage bin and the cardboard boxed Jensen wide range LS woofer (OEM PLL was way too expensive for any family in our neighborhood) has been collecting dust in various basements, closets since '60. In a quick 'peek', the one piece cone doesn't appear to have any stress cracks, but would have to be carefully moisturized like a rare book to even think about applying any power to it, though doubt there's anything can be done with the spider, but at a base efficiency of ~102 dB/70 Hz in a 12 ft^3 cab, not much need for one. 😉
Yes, a straight flare TH = ease of build.
TD's a positive flare TH = big and loud.
T-TQWT or T-TQWP is a negative flare TH = small and low.
Hofmann's Iron Law
Three parameters that cannot all be had at the same time. They are low-bass reproduction, small (enclosure) size, and high (output) sensitivity." Hofmann stated that designers could pick two of these three parameters, but in doing so, it would compromise the third parameter.
Yeah, me n' Freddyi gave Tom a bit of a hard time initially re this and some others Freddyi was aware of, but IIRC Tom claimed no knowledge of them, though his design was sufficiently more advanced to be a much more technically correct 'TH' and no one to legally contest it, so DSL rules! 😉
My neighbor's that I helped build in '56 to complement his K15 DIY kit was an unbelievable experience in a time when typical bass was 80 Hz.
I built a couple of these now, but never one with that skar driver specifically. Seems like one of the better ideas for vented subwoofers
Attachments
Yeah, built a bunch of them for full height corner loading using 'el cheapo' drivers in cardboard tubes decades before (I forget who now) 'invented' cardboard tube HT subs.
So I can just add a few more details and then patent a design myself?
I'll patent the "Half Straight, Half Positive Flare TH= Its still a tapped horn lol
Tom Danleys has a very limited bandwidth before you run into the chaos of a bunch of 1/4 wave freqs that cancel and resonate. That all sounds bizarre and especially if coming out of a big mouth/exit?
the tapered or stepped reduction versions (long skinny bass reflex?) seem to be the perfect compromise for home/car audio maybe ?
i guess it’s the best way to get a big potent subwoofer that’s not plagued with all the pipe noises and issues. but it’s also not a screaming little reflex port/tube underdamped peak or chuffing ?
you get the cone control of the long skinny ‘chamber’, but the actual ‘port‘ size is bigger ?
(if that makes sense? 😝)
the tapered or stepped reduction versions (long skinny bass reflex?) seem to be the perfect compromise for home/car audio maybe ?
i guess it’s the best way to get a big potent subwoofer that’s not plagued with all the pipe noises and issues. but it’s also not a screaming little reflex port/tube underdamped peak or chuffing ?
you get the cone control of the long skinny ‘chamber’, but the actual ‘port‘ size is bigger ?
(if that makes sense? 😝)
In my thread some people poked fun at PMC for advertising its enclosures as Transmission Line when it wasn't an actual "true" TL.... Now it seems that MLTL / Tapered TL is the hybrid winner of the BR vs TL brawl.
If my memory serves me correct, A proper flair is only other way
If my memory serves me correct, A proper flair is only other way
Yeah, if there was an arguement, how could these things not ‘win’ ? I can’t find anything ‘better’ for the ‘ultimate vented subwoofer’. But most definitely ran Into some weird stuff trying to .
If I use 2 Sd folded into 1/2 Sd there’s never pipe resonances/cancelations in the way. nor is there a port velocity issue ?
the pic on the bottom is no different in box volume (assume all the drivers are mounted right at the vent exit). And the tapered version at the top doesnt tune as low?
If I use 2 Sd folded into 1/2 Sd there’s never pipe resonances/cancelations in the way. nor is there a port velocity issue ?
the pic on the bottom is no different in box volume (assume all the drivers are mounted right at the vent exit). And the tapered version at the top doesnt tune as low?
Attachments
Last edited:
I think I meant to delete this part of the post but my thought was;
Tapped Horn
Offset TL
Proper Flair at the terminus/mouth
TaperedTL/MLTL/BR
Any other vented solution has harmonic issues in the FR?
Tapped Horn has limited BW towards the midrange
Offset TL has crazy GD
Proper Flair for Bass is Gigantic?
TaperedTL/MLTL/BR.... Whats to hate?
I wonder how does offset Tapped fair
Last edited:
Not sure I'm following all this, but the way me n' the old one armed ex-Army Ranger did these things originally and later used for DIY PR, exhaust system design was based on bazooka design theory (used for blasting snow drifts also) + the pipe harmonics I always post for reference since it's much easier to follow than that old NACA Tech brief I originally posted.