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Multi-Way Conventional loudspeakers with crossovers

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Old 25th July 2008, 01:15 AM   #111
CLS is offline CLS  Taiwan
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About post#109, I'd like to have a look (and listen) on the other side -- that'd be a huge bass "wave guide" !!
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Old 25th July 2008, 11:51 AM   #112
Bluto is offline Bluto  United States
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The "Wife Pleasers" are too small.

Bluto
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Old 1st August 2008, 07:00 AM   #113
gainphile is offline gainphile  Australia
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Another Nelson Pass OB. Lowther + Seas 10" woofers

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http://blog.stereophile.com/rmaf2007//index3.html

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Nelson Pass is up to good again. Following the wonderful sound of Ella and Billy I heard in the corridor, I discovered Nelson's prototype open-baffle speaker system. It sports both a Lowther PM6A full-range driver and a pair of SEAS W26 10" woofers. The 40"-high open baffle, which at this stage of the game is not intended to be a final design statement, has no side panels, only a central brace in the rear. The system was bi-amped, with the Lowther driver fed using a 60Hz, 6dB/octave high-pass filter feeding a First Watt F3 7Wpc JFET amplifier. The woofers were driven by a Pass Labs XA30.5 fed by a 12dB/octave active crossover. No equalization was employed. That the sound was so good was especially amazing, considering that the digital front end was pieced together at the last minute after the originally intended computer drive arrived minus its charger chord. I look forward to hearing the finished product.
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Old 1st August 2008, 03:40 PM   #114
fergs1 is offline fergs1  Australia
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Greetings fellas, here are my ob's Ive been using for the last couple of years. B200 in baffle with a single vifa pushpull sub crossed at 180hz all made by my mate Nigel otherwise known as Mr Content.Sound fantastic, but I am going to have a play with the b200 + alpha 15 combo currently on Audiocircle just to see what difference when the entire range is ob.
keep em coming
peace and goodwill fergs

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Old 2nd August 2008, 09:03 PM   #115
Saurav is offline Saurav
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Well, it's not an ultimate anything, but I just finished building the baffles for these speakers, and am now working on the crossovers. AE OB12, Audax PR170M0, BMS 4538/18Sound XT1086.

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Old 3rd August 2008, 06:39 AM   #116
SunRa is offline SunRa  Romania
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These are very nice... You'll have to tell us how they sound.
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Old 25th August 2008, 07:12 AM   #117
gainphile is offline gainphile  Australia
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Those are fine looking baffles!!

What wood did you use and what stain ? I see pine baffles in the background?
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Old 25th August 2008, 05:21 PM   #118
Saurav is offline Saurav
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Thanks for the compliments. Yes, the baffles on the old speakers were pine, because I found these 16" edge-laminated pine panels and figured I wouldn't have to cut anything. That had the PR170M0 with a Fountek JP3.0 on top and a Peerless 850146 in the sealed cabinet below.

The new baffles are birch ply from Home Depot. I cut everything with a jigsaw, and didn't upload the pictures that showed how I glued them slightly crooked The stain is Minwax pre-stain conditioner, then Minwax mahogany gel stain, then I mixed in some cherry Polyshades on one coat of the stain, and then it's wipe-on poly on top. I really didn't know what I was doing, and luckily I had the good sense to stop before I tried one more coat and screwed everything up. I hung the baffles from the garage door opener tracks when I applied the stain. Some more photos:

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They sound really good, but I have a lot of crossover work left. I'm fairly satisfied with the active crossover+EQ between the woofer and the midrange, it handles the dipole rolloff and peaks pretty well, so I was able to hit my target acoustic slopes with more or less textbook crossovers. I used LTSpice and Speaker Workshop to play with the component values and see what the filter's transfer function did to the drivers' responses.

The passive crossover between the midrange and tweeter - that's where there's work left. It's been a challenge for me to handle the ~4" acoustic offset difference, and the tweeter is further behind which is backwards from what it usually is. I have a design now that has the drivers more or less in phase, but the phase tracking around the crossover isn't very good. Anyway, it sounded good enough that I brought them into the living room and hooked them up to the stereo. I haven't had too much listening time on them yet, but I'll be tweaking the passive XO over the next few months. I haven't even done the final on-baffle measurements yet, I wanted to get these hooked up quickly so I would have music again.

This is copied from another forum post, but here's roughly what I was thinking when I came up with this 'design' (if you can call it that):

* I wanted to use that midrange because I had it in my previous speakers (the blonde baffles in the background) and like the way it sounds, and to keep the initial costs down

* I had a ribbon tweeter and never liked the integration, my midrange didn't go high enough and the tweeter didn't go low enough. So I wanted a new tweeter, wanted to try a compression driver, and decided to try for some level of 'constant directivity' in the front. So the baffle width was chosen to keep the midrange response dipole-ish up to a higher-than-usual frequency, and then the crossover to the tweeter is at roughly where the midrange's response starts to narrow. I eyeballed these with off-axis measurements, so it's largely handwaving, but that was the goal. On the low end, because of the narrow baffle, the midrange starts to roll off around 500Hz, which is where I cross to the woofer.

* I had the woofers in sealed cabinets in the old speakers, and wanted to try dipole woofers. This is where there seem to be two distinct schools of thought, and I went in the low-Qts/high-Xmax direction. We'll see how it works out. The woofer is pretty flat up to ~700Hz, so an LR4 XO at 4-500Hz works well. Because of that high XO, I didn't try a U or H frame, since any meaningful depth would add a resonance at a lower frequency.

So... hopefully I'll have a somewhat constant dispersion in the front from the bass up to the treble, and the back wave will start out dipole and then fade out at the mid-tweeter XO. I'll put that in the room and see how it sounds.
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Old 26th August 2008, 06:21 AM   #119
SM7UYJ is offline SM7UYJ  Sweden
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Lazy mans OBs

Two converted Ikea bookshelves.

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Old 26th August 2008, 07:07 AM   #120
ALF in AUS is offline ALF in AUS  Australia
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My Goodness!!
I'll feel more inspired next time I go to Ikea.
ALF
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