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-   -   pioneer b20 is on sale... (http://www.diyaudio.com/forums/full-range/124012-pioneer-b20-sale.html)

nebojsa 30th May 2008 06:59 AM

pioneer b20 is on sale...
 
Tonight I was about to order a set of pioneers as well as dayton Ndf20fa tweeter for either a half chang or full version. Since they are on sale, was just wondering if a bipole has ever been tried. Perhaps, sealed enclosure sucha as zilla used but as bipole. Or ml tl bipole? Any thoughts? Seriously tempted to order more.

Scottmoose 30th May 2008 09:06 AM

You'd need a big cab. or heavy Eq if you want any LF out of them.

Kensai 30th May 2008 12:41 PM

Order more. Go surround in sealed floor standers :)

Or maybe go dipole in OB. I ran that way for a long time till I finally figured out what that niggling little issue with them was in the back of my mind. Being whizzered, the back wave isn't even remotely similar to the front wave, so their interaction is alot more rough and weird than say a nice, smooth woofer with inverted dustcap or even better, a planar driver. So, what I propose is 2 B20s (and possibly 2 tweeters) per speaker. Mount one as normal and mount the other reversed, beneath, that way you've got a front and a back wave launching from either side of the baffle. These are not ideal for OB, so you'll likely just be getting into the 70s with these without EQ. I used a pretty serious amount of EQ and was able to get good response into the 50s, as well as eliminating the need for tweeters.

Oh, and I prefer the 5/8" Dayton dome, personally.

Have fun.

Kensai

drwho 30th May 2008 02:09 PM

Scottmoose/Kensai

When you say EQ, are you talking about using an external equalizer and adjusting the low frequencies via the equalizer.

Or do you mean something else?

Thanks

Scottmoose 30th May 2008 02:42 PM

Yes, if you can't use a big cabinet.

GM 30th May 2008 04:52 PM

Re: pioneer b20 is on sale...
 
2 Attachment(s)
Greets!

As already noted, these require big cabs to get the max gain BW out of them, so dual B20s require around 8 ft^3. They make fine MLTLs IMO, but they also work well in a prosound alignment (AKA max flat impedance AKA Wayne Parham's 'PiAlign') if you either don't need to get the bottom 1 - 1.5 octaves due to using a sub and/or you have the ability to pull them out away from walls/corners enough to get some LF gain without excessive mid-bass boost, which of course is desirable for a bipolar alignment. Since these alignments do a good job of protecting the driver down to Fb, they can typically be played at a higher average SPL and/or boosted or minimally compressed signals if you have plenty of clean power on tap, up to around 200 W for a bipole B20.

The downside from my POV is that its typically low tuning and reduced Vb means it doesn't yield what I consider an optimum MLTL alignment due to its excessively high aspect ratio the way I calc them, typically putting the driver too low when optimized without adding a short stand or lower ballast cavity. With the advent of MJK's software and how pleased folks are with aspect ratios Vs driver location that I've historically avoided from a theoretical POV, it may be much ado about nothing, so you may want to try this ~ear height variant if a small footprint is required, though of course it will require some form of wide stand to counter-balance its top heaviness:

L = 46.25"
WxD (CSA) = ~112.11"^2
zdriver = 9.25"
zport = 43.25"
dport = 3.5"
Lport = 3"

All dims inside (i.d.) and approximate, 0.2 lbs/ft^3 polyfil stuffing density simmed.

GM

Godzilla 30th May 2008 06:33 PM

http://www.zillaspeak.com/pioneerb20-3cubox.asp

The yellow line is the closed box. Looks like you can get more bass from the B20 but listening to the sealed box i do not feel it's lacking especially when compared to smaller boxes using Fostex or TB drivers. The B20s sound fuller. I always liked this driver and think it's worthwile to own. Some have been disappointed with it. But once a tweeter (pick your poison) is dialed in, it does sound very good. Plus, you don't worry much about the driver getting pushed in and destroyed since it's pretty cheap compared to similar Fostex. I feel the B20 offers its own set of pro's compared to some of the Fostex cons... but Fostex are better overall IMO. Certainly a different sound. If you want a relaxed, laid back sound go for the B20 (and miss some detail and speed). Fostex offers the detail and speed but their presentation is more forward. Enjoy!

nebojsa 30th May 2008 07:50 PM

Thank you guys for all of your responses, I will be ordering Pioneers tonight.
GM mltl you specified is for a bipole, correct? The foot print is not large, which is the way I would like it. Sorry, I've read it number of times but still get confused on terms. Thank you for your patience.

GM 30th May 2008 09:06 PM

Correctomundo!

OK, what's not clear?

GM

Scottmoose 30th May 2008 09:20 PM

Probably the dimensions, if he's not used to them.

OK: short translation[s]. Dims. will be internal.
L = 46.25" (cabinet height)
WxD (CSA) = ~112.11"^2 (cabinet cross sectional area, i.e. if you multiply width x depth, this is what you'll get.)
zdriver = 9.25" (distance of the driver centre from the internal top of the cabinet, or, more accurately, from the sealed end of the line)
zport = 43.25" (distance of the port centre from the top of the cabinet / sealed end of the line)
dport = 3.5" (circular port diameter)
Lport = 3" (length of port)


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