Big Big box. Look like as big as you can afford and the either make it aperiodic or EQ down the (expected fairly large) bump as you go down in frequency.
500 litres gives you butterworth Q, but for a sub, in a room, lower is better. But you can’t build a box big enuff to get to the sweet spot. Use the next room as an enclosure and you could get close.
dave
500 litres gives you butterworth Q, but for a sub, in a room, lower is better. But you can’t build a box big enuff to get to the sweet spot. Use the next room as an enclosure and you could get close.
dave
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The MLTL is a quarter wave pipe, so 10’ (3m) gets you to 27Hz, but the mass loading will bring that down. You could make a pair of em long horizontal MLTL’s stacked on top of each other, one ‘firing’ to the left, the other to the right and maybe help balance out some of the forces in the cabinet.
I'm not sure how well suited your drivers are to an MLTL, they have fairly high Qts which I think is fine, but, Somebody smarter than me will have to chime in on that.
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Given the response of the driver sealed i see NO gain, only loss with an ML-TL.
You want less bass gain, not more.
dave
You want less bass gain, not more.
dave
Right, that's where the one fold comes in. To oversimplify, ten feet one way, ten feet back, 20' total, or a quarter wavelength of 14hz.
Interestingly, Winisd is showing me a very, very nice looking result from a 600+L box tuned to 11hz. F6 in the 15hz range, good excursion control, very flat. Hornresp doesn't quite agree on the frequency response though, so I'm not believing it.
Interestingly, Winisd is showing me a very, very nice looking result from a 600+L box tuned to 11hz. F6 in the 15hz range, good excursion control, very flat. Hornresp doesn't quite agree on the frequency response though, so I'm not believing it.
Do I though? Seems to me room gain in this rather large room shouldn't really kick in until the mid-20s, and this driver sealed starts rolling off in the high 30s. I would think I'd want more bass gain than that.
I would not do reflex with those, the specs are not fit for it. Sealed would be best, (ML)TL is also possible. Reflex will be a very bumpy one note bass except maybe in extreme big cabinets.
I really like vented boxes, but if I had that particular driver I'd chuck it in a sealed box.
Find a couple Pro 21" and we can talk vented designs with force cancellations and all the bells and whistles.
Find a couple Pro 21" and we can talk vented designs with force cancellations and all the bells and whistles.
You asked for a "huge" enclosure and mentioned tapped horns. This is a 218 ROAR (8th order quarter wave based series bandpass).
Max spl is with 1500 watts (750 watts per driver) and one Pi radiation angle. You should probably add at least 6 dB room gain in the bottom part of the passband. With corner loading and room gain you could easily see 140 dB spl at 13 Hz if needed.
Thanks for the recommendations, although I'm curious why exactly you think a reflex would have a bumpy response. A large, low tuned reflex is the least bumpy thing I've modeled so far.
If you think you have too much space, take a look at this:
https://www.diyaudio.com/forums/sub...-horn-vs-modern-vented-box-2.html#post3794298
https://www.diyaudio.com/forums/sub...-horn-vs-modern-vented-box-2.html#post3794298
Because the values of the driver are what they are, you will have to eq a bit to smooth out the response, that said... You just need basic shelf eq to make it flat, the port I chose is "too small" but if you use aero ports you might even appreciate the slightly higher distortion and consider it extra output...
I do not agree with the rest here that it will have significantly higher group delay than a sealed box.
This is in halfspace.
I still don't like it.
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As it's for HT, go with as many large high excursion drivers as you can fit, mount them push/pull, ported with a ~20Hz tune and either use a BOSS or transducers for the tactile below 20Hz. AVS DIY Speakers and subs tend to have more appropriate builds than here.
For instance, you could easily do multiple full Marty sub builds into the bar enclosure volume available and at least one at the front.
For instance, you could easily do multiple full Marty sub builds into the bar enclosure volume available and at least one at the front.
I’d strongly recommend a sonotube from personal experience... mine is almost 20 years old and I still find the freedom from boxy resonance or boom intoxicating..
I don’t really understand the appeal of a transmission line enclosure in most circumstances given their size and complexity... why not a large ported enclosure with a large low frequency port? Seems easy enough just to tune the port for a more transmission line type of response? I’m working on a two way with a large enclosure and very low extension ...i’ve never measured my sub but subjectively I’d guess it cranks out about 115db at 15hz easily
Big room.
A long labyrinth in the bar with a even number of bends will go the lowest and get the most bass out of the driver(s). No particular design issues, just buy enough pillow-stuffing to fill it. Rear wave cancellation just a matter of how far the exit port is from the driver.
Good to think in terms of driver resonance. Any non-infinite sized box (except horns) leads to a system tuning and drop off below. A stuffed labyrinth depresses the driver resonance and the speaker resonance and lets you drive the driver lower.
BTW, a big enough bar might provide quite a good open baffle. Again, uses the driver output well to fill the big room.
The needs of commercial manufacturers are different than the way DIYer works - and has distorted the judgment of DIY people about what their options are.
B.
A long labyrinth in the bar with a even number of bends will go the lowest and get the most bass out of the driver(s). No particular design issues, just buy enough pillow-stuffing to fill it. Rear wave cancellation just a matter of how far the exit port is from the driver.
Good to think in terms of driver resonance. Any non-infinite sized box (except horns) leads to a system tuning and drop off below. A stuffed labyrinth depresses the driver resonance and the speaker resonance and lets you drive the driver lower.
BTW, a big enough bar might provide quite a good open baffle. Again, uses the driver output well to fill the big room.
The needs of commercial manufacturers are different than the way DIYer works - and has distorted the judgment of DIY people about what their options are.
B.
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A TL isn't very complex when you're making a 10' long box. It would be a little easier to just build a single-fold TL than to figure out the port. If I model a large bass reflex with the actual dimensions I have available, I end up with some 1/4 wave resonance (and not in a particularly good way), or the port velocity gets out of hand.
In a tapered (smaller at terminus) TL, how undesirable is it actually to have a little underdamped peak at resonance if the resonance is under 15hz? I can't seem to make that go away due to, I assume, the driver's QTS. I'm not worried about the actual FR peak, or even transient response or some ringing in the infrasonic range. I'm more concerned with what it would mean for the system's behavior an octave or more above the resonance. If the effects above 20hz would be significant, can they be mitigated by lightly stuffing the line near the terminus to squash that peak?
In a tapered (smaller at terminus) TL, how undesirable is it actually to have a little underdamped peak at resonance if the resonance is under 15hz? I can't seem to make that go away due to, I assume, the driver's QTS. I'm not worried about the actual FR peak, or even transient response or some ringing in the infrasonic range. I'm more concerned with what it would mean for the system's behavior an octave or more above the resonance. If the effects above 20hz would be significant, can they be mitigated by lightly stuffing the line near the terminus to squash that peak?
I use a flaired 5” port and get zero audible resonance...port velocity is low... It’s underdamped but tuned to around 16.5hz... i dont think its a problem since it’s so low
But the way I have it tuned creates a more gradual rolloff... something between a typical TL and typical bass reflex... then corner loaded... seems to create a very smooth response with room gain...
If I understand correctly, you're suggesting a non-resonant transmission line that approximates an infinite baffle? I've been giving that some thought since Dave recommended what amounts to an infinite baffle. I like the idea, and it might be interesting to design a resonant TL then experiment with stuffing (and perhaps terminus size) to move it around on the IB-to-1/4 wave continuum.
I hadn't considered an open baffle. I'll have to read up on that concept. Thanks for the input.