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BPH subwoofer - driver to match

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bitSmasher View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bitSmasher Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:03pm
Have you seen the Selenium sub plans? Very familiar...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sn95 Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:04pm
That looks like a selenium horn.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:08pm
Originally posted by LeruSound LeruSound wrote:

Yeah, itnis chocking... I will show you The design..


You have decent compression and gradual expansion... that's not a Bandpass-Horn hybrid, but a Front Loaded Horn or "true" horn you might say. Given the dimensions, bass to low-mid oriented. Should be useable from 60-65 Hz up to a solid 200+ Hz. The two bends and side firing speaker doesn't allow it to go up to ~500 Hz or so, but if it doesn't sound right crossed at 180 Hz, it's more likely not the right speaker for the intended frequencyband you want to use it in. When I look at the list in your first post + the 15PS100, I see sub oriented speakers with too low EBP. For this horn you need higher Fs, lower Q and preferably high BL. I saw something like want to use it also from 40 up to 180 Hz, but that it will not do. To get down to 40 Hz the horn needs to be at least twice as long and have at least 4 times the mouth surface and/or used in multiples, combined with the right speaker. At the same time such a speaker will have low EBP and not be able to reach the higher frequencies, at least not properly. And also, longer horn usually means more folds or bends, limiting even more the highest reachable frequencies. Below the cut-off that will sit around ~60 Hz in this design as is, the speaker will flapper itself to destruction in short notice whatever speaker you would mount in it.
If it needs to be B&C, have a look at : 15NDL76, 15NW76 and maybe 15PLB76

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:08pm
It is, its a HB1502B1 plan cutted in half
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:21pm
My plan could be not to Force my midbass over 180, but maybe stay in 80-160 without bad sounds from it. So, would u advice me to stay with 3.5" VC with that low Qtss?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:32pm
Originally posted by LeruSound LeruSound wrote:

U think so?

I don't think I no....

the horn path is to too long, so the higher frequencys will cancel out, the highest it will play is the shortest length of the shortest fold 1 qtr space. But also too short to do 40hz. a BPH plays higher and lower due to the band pass effect of the 2 chambers. This design is a straight up horn design.

As Peter has said Wink 


Edited by bee - 05 April 2016 at 11:36pm
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Peter Jan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2016 at 12:21am
Originally posted by bee bee wrote:

a BPH has 2 chambers front and back, look at the es18 bph design, down scale it to a 15" you wont be far off what you need.

BP with two tuned chambers is a 6th order BP. One or two flared horns (or rather flared ports in that case) makes it a hybrid or BPH. With only one horn (port) makes it a 4th order BP(H), but it's still a bandpass resonantor.
The hornpart (if you want to call it "horn"), is only there to extend the frequencyrange some more than the bandpass would give on it's own. The length (or lack of length) of the "horns" in BPH designs is an indication that it's won't do a thing for low freqencies as a horn, because it's really noting more than a flared port (to get a bit more bandwidth) with a tuned resonance, that dictates how low it will go, just as a regular BR does. Every BPH has maybe a little compression or even no compression at all, just look at how a speaker 'fire' in the so-called horn and you know what you have... no compression -> no hornworking or more to the point : the resonator will be THE dominant factor by far.

A horn is an impedance transformator, not a resonator, which makes the Fs of a speaker not all that relevant to begin with and makes speakers behave rather different compared to BR, BP, BPH. Some T/S parameters needs to be in the same neighbourhood whether for horn or BR, BP, BPH, when used for the same frequencies, but some specific parameters have more importance for horns and other have more importance for the resonantor family.

If you can fit the proposed design in your system for use from 80 - 180 Hz (even lower than 80 is possible, ~60 Hz would be the usefull limit), you have to look for speakers with low Qes-Qts, high BL in the first place. The Fs value is not that important, but higher Fs gives higher efficiency bandwidth product, which is a first strong indicator for how high the speaker in a horn could reach if the design supports it by means of smooth bends and as little bends as possible. Le is parameter that can't be too high, but 180 Hz is still relatively low, so you can get away with Le values up to 1.5 mH. No current B&C 15" speaker is really suited for use up in the several hundreds (Hz), but the ones I pointed to earlier in combination with the suggested design, would be very decent candidates from 60 Hz. That cab can do it properly and these B&C's sit almost ideal parameterwise for use from 60 Hz even a bit lower with the proper design (read : bigger). If 80 Hz would be the lowest you need or want it to go, you could as well use a smaller design, because part of the size, the volume would sit redundant, taking up space and doing nothing usefull. If size is of no importance, you can just use it as is of course. It will work every bit as good, just be a bit bigger than it needs to be.
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bee View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2016 at 12:27am
That makes sense, ive never looked at it this way cheers...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2016 at 1:04am
B&C 15NW76 is probably your best bet, they suit horn loading quite well.  I tried designing kick bins around them many years ago.  I got the cab design wrong but that wasn't the drivers fault.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 28 April 2016 at 5:37pm
Thanks everyone! What about the 15NW100 in it?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 08 July 2016 at 6:45pm
Hi guys: Finally i tryed it with the 15NW76. Too much high frequencies requied heavy equalizations, further more, i cant feel that bass impact i wanted. So, it´s ok to stay with a low QTS, high BL, but for my use, maybe i would choose the 15NW100, for a more bassy action. i also need it to melt with an Hog Scoop, so that 3 inches VC of the NW76 is not coupling well...
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