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BSC in a dipolar speaker

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  • Chris Roemer
    commented on 's reply
    (I know you're not a fan of PMs - but I'd appreciate some of your knowledge)

    Hey Bill (hope you're having a good winter up there in NH - my wife lived there once),

    Being an enthusiastic proponent of WinISD (I typically use 0.50a7 myself), I was wondering if you knew where ISD stores drivers - once its "Drivers" folder fills up.

    I still add drivers (nearly every day), and I've got about 500 that I added (that are in the Driver folder), but there are no NEW entries in there since 2014. I just added one today, and it stored it (and I can recall it), but I have no idea where the data is being kept. I'm pretty good w/'puters (and used to program quite a bit), and have looked into this years before - but I can not figure it out.

    If I wanted to move on from my 15 y.o. Vista machine, I'd like to know that I wouldn't have lost the last 1000 drivers that I entered into the DB.

    Thanks

  • jhollander
    replied
    Plate amp for the TB and the Zaph filter on the 4 B3Ss would get you close

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  • banningr
    replied
    http://speakerdesignworks.com/Cinderella.html Similar build to what you're describing

    Very similar in appearance/driver arrangement to what I have in mind and what an intriguing crossover.......3.5 way that combines 1st, 2nd and 3rd order topologies?? Maybe I should wire the inside pair in series to a binding post, do the same with the outside pair and have a completely external crossover. That would certainly make playing with the design easier and allow for easy A/B comparisons. Looks like a simple cap on the B3S's and a plate amp for the TB's might even be viable option.

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  • billfitzmaurice
    replied
    You can go as high as 250Hz with the side firing woofer without directionality being a problem when they're in the same box. Even 300Hz may be OK, I just have personal experience going to 250Hz.

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  • chrisn
    replied
    http://speakerdesignworks.com/Cinderella.html Similar build to what you're describing

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  • banningr
    replied
    Well it sounds like 4 B3S's on the front for sensitivity and a 200hz crossover is the way to go. I'd prefer not to cross lower for power handling of the HiVi's. Bi Amp and active crossover will be an option for a later date.

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  • jhollander
    replied
    Best to keep the side woofer below 200 Hz for directionality issues. You could use a electronic x-o between the B3Ss and the TB.

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  • billfitzmaurice
    replied
    Put the HiVi on the front vertically arrayed. Two on the front and two on the back isn't going to do anything to improve sensitivity where you want it, in the listening area.

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  • banningr
    replied
    Planned project is as follows and based on drivers I have on hand with no home. 5"Wx9"Dx48"H with a Tang Band W-740C mounted on the side and 4 HiVi B3S's mounted either 2 front and 2 rear or 4 on the front tightly spaced in either case, wired series / parallel and all in phase. I intend to use the circuit found on the ZaphAudio.com site to tame the response and possibly the BSC as well. Crossover between them and the Tang band sub to be somewhere between 200 and 500Hz. I just downloaded Jeff Bagby's crossover design software 3 days ago and am stumbling through figuring out how to design something that sounds decent. Enclosure will net 2 subenclosures that are .4 cu ft each. Tuning the bass enclosure to 33hz gives a reasonably flat response and an f3 of 37hz, acceptable group delay and no excursion problems according to WinISD. The biggest issue with the 3" HiVi drivers appears to be efficiency, which is why I'd like to use 4 of them. Any thoughts, advise or comments would be much appreciated. I've built many speakers designed by others but have no design experience of my own beyond subwoofers.

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  • jhollander
    replied
    That's a good question wrt is baffle step compensation more or less with a second woofer mount in the back. The answer is to measure, but assuming the listening axis is to the front driver with a typical baffle peak the rear speakers response will wrap and notch where the response is out of phase. That notch location could reduce the magnitude of the baffle peak.

    We don't know what your building if this is a subwoofer or 3-way woofer, much of this discussion is N/A.

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  • billfitzmaurice
    commented on 's reply
    BSC is used to account for the shift from half space to full space loading that occurs where the baffle is less than a wavelength in dimension, so it would be used in this case. Since it's determined by the baffle dimension the number and orientation of drivers doesn't matter. This configuration will result in a cancellation notch where the front and rear radiations meet at 180 degrees, so it's not without its issues.

  • banningr
    replied
    I apologize for my mistaken understanding of the terminology. I believe what I am intending is referred to as bipole. Speakers on opposite sides of the same enclosure (front and back in this case) in phase and facing out of the enclosure. In this instance, is baffle step compensation needed? If so, is it the same as, greater to or less than a single front facing driver?

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  • jhollander
    replied
    In phase means you have a monopole, The rear woofer out of phase with a front woofer is a dipole. Some time you see in phase woofers with one of the baskets reversed (pointing out/ exposed) for subjective distortion improvements.

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  • banningr
    replied
    In phase. I would think out of phase drivers in a common enclosure would cancel the effect of the enclosure rendering it pointless.

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  • jhollander
    replied
    Originally posted by banningr View Post
    Not sure if this matters but I'm not planning an open baffle, just separate identical drivers front and rear in a common enclosure.
    Depends how they are wired. If out of phase then the question becomes why?

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