>>> "I have not compared the modified driver to the Fostex I have on hand but will soon to see if the B20s still sound veiled and congested."
>>> Any updated results ? Thanks
Yes, they still sound veiled and congested, lol... but i prefer them without dustcaps. I cut them off so i could replace them but decided to leave them off... the difference is noticeable but room placement and application of tweeter might dominate overall... now i am playing with Wild Burro Betsy's which are much cleaner than B20s... they've captured my attention. But the B20 still has that nice warm, easy on the ears quality that so many enjoy... including me. Maybe the ultimate 'starter' wide range driver. Everyone should own a pair and blend a tweeter of choice (i still like the piezo best) just to get a reference point to compare other speakers too. Compared to my old B&W's they sound open, crisp and clean... compared to fostex they sound mellow and forgiving.
Godzilla
>>> Any updated results ? Thanks
Yes, they still sound veiled and congested, lol... but i prefer them without dustcaps. I cut them off so i could replace them but decided to leave them off... the difference is noticeable but room placement and application of tweeter might dominate overall... now i am playing with Wild Burro Betsy's which are much cleaner than B20s... they've captured my attention. But the B20 still has that nice warm, easy on the ears quality that so many enjoy... including me. Maybe the ultimate 'starter' wide range driver. Everyone should own a pair and blend a tweeter of choice (i still like the piezo best) just to get a reference point to compare other speakers too. Compared to my old B&W's they sound open, crisp and clean... compared to fostex they sound mellow and forgiving.
Godzilla
you wouldn't happen to have any pictures of this would you?
also does anyone know how long to make the inner panels of nelsons tl? the one plan i saw doesn't have that dimension labeled.
You have to do a little arithmetic but it is here (and IIRC this is pretty much straight off Nelson's sketch.
dave
The lowpass was about 1200. The crossover was a simple textbook 2nd order lowpass on the B20 (1.8mH, 10uF IIRC) with the attached as a high pass on the JBL 2426H driver. The lowpass would need additional refinement though. The highpass obviously has a lot of frequency shaping- horns aren't easy for XO design!
The shown XO is for use with a large 15", the version used with the B20 had the 3 ohm swapped for 4, and an l-pad between the notch filter and the series resistor, turned down about 5dB. And for those who aren't clear: The first image is the impedance correction for the 2426h, the second are series components doing the XO/shaping on the 2426. This XO does NOT bring up the >10kHz content, this driver is heavily damped in the top octave.
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Some danged fool wrote it up
Pass The Bofu Building a transmission line cabinet for the Pioneer 8-inch full range driver. Article By Jeff Poth
Pass the Bofu? What a stupid name!
Pass The Bofu Building a transmission line cabinet for the Pioneer 8-inch full range driver. Article By Jeff Poth
Pass the Bofu? What a stupid name!
I've been looking for a pair of speakers to build for a friend in the "relatively cheap but good" category. This is not altruism. I just can't stand listening to music on his current speakers. 
Anybody tried the B20 in a line array? At the current price, 4 per side is cheap enough for an experiment. How about an MTM? Not necessarily run full range. I could do a conventional crossover to a tweeter. The BOFU would fit in his living room. How about a double-wide MTM BOFU? I've got a nice sheet of baltic birch plywood and a table saw. What would you do with them?
Anybody tried the B20 in a line array? At the current price, 4 per side is cheap enough for an experiment. How about an MTM? Not necessarily run full range. I could do a conventional crossover to a tweeter. The BOFU would fit in his living room. How about a double-wide MTM BOFU? I've got a nice sheet of baltic birch plywood and a table saw. What would you do with them?
Line arrays with large wide BW drivers don't work for me, but a decade or so ago when the B20 was (re)discovered, I posted about a cobbled together MTM OB with it and its woofer variant with a square frame piezo horn nestled in the lee between the two that I was pretty impressed with once I damped the woofer's excessive HF. I'd planned to finish them as towers (MLTLs), but 'life' is still keeping me from building them, so the components collect dust and the baffle was turned into a folded 4" driver MLhorn prototype.
GM
GM
Hmm, I´m afraid I have to concur with GM. Line arrays with small fullranges can be a marvel (25 very cheap Visaton 3" in one slim tower look like something and you can feed them 750 Wpc), but with 8" you´ll have to do a very tricky Xover.
The piano jumping up and down unless you sit at least 10 meters away from your boxes...nice for a laugh, not good if you want to enjoy music.
Sorry.
Pit
The piano jumping up and down unless you sit at least 10 meters away from your boxes...nice for a laugh, not good if you want to enjoy music.
Sorry.
Pit
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OK. The line array idea was just a "what if..." I'm glad that you and GM gave me that feedback. I just ordered 4 B20s. I'm thinking about an MTM with a tweeter between and a 3000-5000 crossover. I have a pair of rectangular frame double piezos (can't remember the brand or model number) that might work, or maybe a tweeter in the 94 db/watt range.
for the buck.- Status
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