Pioneer B20FU20 application thread

[Mayuri]

Hello everyone!

I've been looking the Pioneer BOFU drivers from PE with gleaming eyes for over an year now, and have finally decided to order them, even with the crazy postage fees they put in packages coming from US to EU.

I am thinking I might get an inexpensive HT upgrade from them, or just put them in large BIBs for casual listening. But BIB is way too large for my living room, since it's only 3m x 4m. What kind of small-ish enclosures would you guys recommend for these drivers?

Best Regards,
Simo

[IG81]

I never tried them myself and am intrigued as well. What would be helpful to know to start with is, do the published T/S parameters hold up to measurement? I've been had before with drivers far enough form specs to make them unsuitable for the desired enclosure.

IG

[Godzilla]

http://www.zillaaudio.com/pioneerb20-piezo.htm

http://www.zillaaudio.com/pioneerb20-3cubox.htm

Single Driver Website

I think you can use the BOFU in a small sealed cabinet with very good results. But add a tweeter.

Zilla

[GM]

Originally Posted by IG81

......do the published T/S parameters hold up to measurement?

Well, this driver's specs has changed over the decades as has how folks measure them and my 10+ yr old drivers spec a larger cab than the PE's by about 13%, so you could always 'pump up' PE's for a bit if you're worried about it being too small....... Regardless, there's been enough different alignments built using PE's over quite a few years now with nary a comment about them AFAIK, so unless something has changed recently that I'm not aware of.........

Anyway, a 3 x 4 m room is only slightly larger than the room I'm sitting in, so plenty big enough for some good size MLTLs if not full of furniture/fireplace/whatever, so my usual suggestion for drivers that need a larger than average cab to go low is to build the biggest cabs that can be tolerated and tune it in-room.

Nelson Pass's TL has been getting some good reviews lately and sealed, BR, MLTL are easy enough to calculate, so what's the largest cab that can be tolerated?

GM

[Mayuri]

I think that when looking at bass extension and cabinet size, a small sealed one would be best for me (I also happen to like sealed cabinets sound). First of all, I have a quality sub that can take over at about 70-80 Hz. Second, the listening room is my living room, so there's a quite of bit of furniture, so a huge enclosure would be cumbersome.

How directional are these drivers, is there any sense in making a 5 speaker HT with these or should I look at some other drivers for the upgrade. I'm now using 4 Cyburgs Sticks and a matching center speaker, so can this project be an in sound quality?

[norman bates]

um, very directional past 5khz (like 2-3 people wide at 10'), but phase plug may (should ?) help.

Norman

[Ed LaFontaine]

published T/S parameters hold up to measurement?

I have 2 B20FU20-51W's that I bought at PE's most recent tent sale. One appears to be in "like new" condition. The other is a bit worn and was subject to someone's ill-fated experiments. Below is a list of parameters. PE's data is dated January, 2002. My "a" data is from the experienced driver. My "b" data is from the "like new". They were measured this morning on a WT3.

*** Fs**** Re****Lvc****Qes****Qms
PE *43. ***6.28***1.21***.62****3.02
a **40.4 **6.23***1.40***.59****2.64
b **40.4 **6.13***1.19***.60****2.62

[Ed LaFontaine]

The above response plot is for the BOFU in a MLTL. The enclosure internal dimensions are 42" High, 9.5" Wide and 12" Deep. The driver is centered 6" down from the top. A port tube of 3" diameter X 6" long is centered 4" from the bottom of the enclosure.
The slope of the response was chosen to offset some of the "boom" resulting from room gain.
A simulation was done to compare with a tapered TL alignment.
This Mass Loaded alignment is essentially free from the ripple associated with the tapered alignment, allows tuning of the bass slope,...and is easier to build, particularly if you can only accept a folded taper.
As it may not be easy to see, the response is @~91 dB just below 100Hz. The "knee" of the response is -6 dB @ ~34 Hz.

[GM]

Originally Posted by Mayuri

How directional are these drivers, is there any sense in making a 5 speaker HT with these or should I look at some other drivers for the upgrade. I'm now using 4 Cyburgs Sticks and a matching center speaker, so can this project be an in sound quality?

The B20 is a great 'bang for buck' driver wherever it's relatively dirt cheap, with a very lively, toe-tapping presentation that works surprisingly well in a HT due to the greater directivity being normally required, but as a wide BW 'upgrade' with maybe just a super-tweeter you're going to have to start with a pretty low expectation by today's lofty standards.

For your app then, the B20 would be a good choice for filling in the Cyburgs's anemic first decade and converting it to a sealed or even OB, mids/tweeter alignment, but I imagine there's better, competitively priced choices available to you locally for this type of upgrade.

GM

[GM]

Originally Posted by Ed LaFontaine

I have 2 B20FU20-51W's that I bought at PE's most recent tent sale.

Thanks, even better than I'd hoped for!

GM