are bandpass subs passe compare to "horn-sub"? - diyAudio
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Old 19th September 2007, 10:36 PM   #1
freddi is offline freddi  United States
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Default are bandpass subs passe compare to "horn-sub"?

lets hear some opinions - are BP all one-note wonders as horn designers usually feel?

rough guestimates -

120liter BP4 with 500uF series cap
http://img264.imageshack.us/img264/2...p4500ufzu9.gif

158 liter Bill Fitzmaurice Table Tuba w. MCM8
http://img66.imageshack.us/img66/925...xsplmcmvh6.jpg
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Old 24th September 2007, 11:53 AM   #2
Volenti is offline Volenti  Australia
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I've used bandpass quite a few times, mostly in car audio where I use the natural cabin gain to smooth out the response, it's not my preferred option (I'm a sealed box guy) but it has it's niche applications where it's the best tool for the job. (and it's choosy about drivers, low VAS high Q = yuck)
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Old 27th September 2007, 02:33 PM   #3
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Bandpass enclosures have their place - primarily when the design objectives call for something very small with a good deal of output, with less of an emphasis on bass quality. The resonant nature of the acoustic bandpass filters means that they're going to store energy and release it over a longer period of time, so transient response won't be as good as a sealed box. Bandpass boxes are also much simpler to build than a horn-loaded enclosure, however, so that's another reason to look to bandpass designs when you need extra output. Pro audio seems like another area where bandpass loudspeaker designs are widely used -- you've got this huge space to fill, and you don't want the enclosure to be enormous, and the resonance of a bandpass enclosure is tolerable.
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Old 29th September 2007, 03:50 PM   #4
freddi is offline freddi  United States
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I've had a couple - large (too large) BP4 and small BP6A - memory says the BP4 if upper speaker rolled in correctly was reasonably taut but thats a long time ago and I didn't use the same reference tracks as today such as bowed bass and drumkit.

Geddes seems not to fear BP C&L can be used in some but large caps are costly

for home use - what driver size and parameters make good BP? - 12" with Q ~0.45?

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Old 30th September 2007, 12:27 AM   #5
GM is offline GM  United States
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The B&C 15PS76 looks good on paper with rear chamber Vb setting the gain BW of course........
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Old 30th September 2007, 01:35 AM   #6
freddi is offline freddi  United States
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hi GM - got B&C laying around - think 15pzb40 + 15trx40 - had suggested alignment from Earl G. with front chamber larger than rear but drive crashed and gone -WinISD locks up my pc -

what might work? long xmax 12" might be fun but don't have anything with more than 6mm - getting into organ and lower orchestral region w/o strain is needed - tapped horn could be good - BP might tie me over

did the drought break at all? - "" got about 1/2" rain in pan on my deck - - probably runoff from trees - most of the storm front went north -

Freddy
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Old 30th September 2007, 02:58 AM   #7
GM is offline GM  United States
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Greets!

15pzb40 with rear < front will be a very high gain, narrow BW mid-bass BP based on the specs I have. More like a K15 on steroids without the HF BW, though at a glance even with a modest size rear chamber it looks good down into the teens on paper if there's any room gain of note, but the tiny front chamber means vent problems if not horn shaped. I've never tried it, but I wonder if such alignments would benefit from a reverse tapered vent to reduce 'chuffing'? Seems like someone would have already tried and patented it if it held promise.

GM
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Old 30th September 2007, 12:25 PM   #8
freddi is offline freddi  United States
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IIRC EG uses pan-pipe front vent - I can get an on-screen result (if AJ is ballpark) which looks ok with 500uF series but good cap of that value add up to as much $ as some stamped-frame woofer

sensitivity isn't very high - about 92dB halfspace @31Hz - does the cap-version predction look ok for nominal 80Hz xover?

Z drops to around 6.5 ohm around 30Hz to give some "boost" with ~constant voltage amp 15pzb40's 8mm xmax hits on AJ with 25vrms when the cap is introduced

15pzb40
http://img292.imageshack.us/img292/2...zb4033vyf8.gif

15pzb40 BP vs 2nd and 3rd order sealed box
http://img216.imageshack.us/img216/4...vs60lbrlw0.gif
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Old 30th September 2007, 07:52 PM   #9
GM is offline GM  United States
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Greets!

I'm not into the 'ringy-dingy' series cap 'thing', I prefer something more along the lines of this BP for < 80 Hz since once the vent modes are damped I'll have a ~ IB sealed response except with a little extra gain and a lot of mid-bass damping in < 8 ft^3:

GM
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Old 30th September 2007, 07:54 PM   #10
GM is offline GM  United States
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1 W excursion:
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File Type: gif b&c 15pzb40 bp excursion (1.0 w).gif (6.8 KB, 182 views)
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