| 3 Pi plans request [message #63217] |
Mon, 21 June 2010 09:28  |
spkrman57
Messages: 522
Registered: May 2009
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Illuminati (1st Degree) |
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Wayne,
Please send me the plans for the Lambda td12 and B & C DE-250 please.
I have a curiousity and may try out the Lambda drivers as a few friends of mine tried out the 15" versions (td15x I think - rubber surround), and I thought they sounded decent.
Have you thought of 4 Pi plans for Lamda 15" drivers yet?
Regards, Ron
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| three π / four π comparison [message #63250 is a reply to message #63247] |
Thu, 24 June 2010 10:05  |
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Wayne Parham
Messages: 18691
Registered: January 2001
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Illuminati (33rd Degree) |
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I think you've probably seen the datasheet for the four π loudspeaker:
I haven't had a chance to do a spec sheet like that for the three π, but I do have a lot of data gathered during the design phase. I will make time this summer to drag one outdoor to measure. I'm a little slower doing that these days with the little 3-year-old Eddie running around. I did, however, make a video of the process I use to measure the position of the forward lobe (and vertical nulls), and it was done using a three π speaker. I thought it would be interesting to DIYers building similar matched-directivity loudspeakers, so I posted it online:
This shows the three π loudspeaker being measured, and the response chart is clearly visible on the computer screen in the foreground of the video. This was done indoors, so room modes are clearly evident below 200Hz, but you can still easily see the overall response curve. It would just be smoother down low in an anechoic environment, a smooth gradual rolloff like T/S sims show. I wasn't really worried about room modes in this test, because it was a study of behavior in the crossover region. Again, I'll take these speakers outdoors sometime over the next couple of months and get a spec sheet like I have for the four π.
Please forgive the car analogies, my mother's side of the family owned several Chrysler dealerships and has for three generations. Had Packards and Studebakers when those companies were still around too. My Dad opened the first large Porsche dealership in Tulsa in the early seventies, so I grew up around them, drove in the very first 930 Turbo that was delivered in 1976. I was always at the race track with Peter Gregg in the late 1970's, as his Brumos legacy made history on the track. He and my father were friends. So cars are in my blood.
The reason I drew the analogy to the Porsche and Ferrari is, like both of those car companies, JBL and AE are both known for making excellent products. Also, like those car companies, one is known for its reputation for building its products with hand-fitted parts using fine craftsmen, the other more for its precise mechanical approach. I think most would agree that both car companies make fine products, just different approaches, each having its own unique traits. But in spite of their differences, both perform well and are a joy to drive. Likewise, I find that both loudspeakers are excellent, both sound great, both are a joy to own and neither has anything about them that makes me want to look for something more. I could live with a pair of either model of speakers, and used with some good subs, I think I would be happy with my sound system for the rest of my life.
When I brought in the AE woofers for evaluation, my thinking was I'd measure them and if they were good enough to use as upgrade parts, I'd add them as an option but if not, I'd silently shelve them and just not mention it. The JBL woofers have been my favorites for a long time, sort of setting the standard for me for top-of-the-line midwoofers. If the AE's fell too far below the JBL's in performance, as I said, I'd shelve them. Or if they left the JBL's in the dust, I'd probably look at replacing all JBL woofers (i.e. 2226) with an AE part for an upgrade path.
The things to watch for are harmonic distortion, primarily at the low end but also through the passband and breakup in the top end of the scale. Harmonic distortion will tell you how well flux modulation is controlled, how good the Faraday rings are. That's not a trivial thing, because you have to balance getting enough conductive material in the motor, in the right place, to counter flux modulation without putting in too much and making the motor weak. Cone breakup characteristics are determined by cone shape and composition, including the dustcap. Finding the right shape and cone material is probably difficult enough, and then doing it reliably and consistently is another thing as well. In both of these areas, harmonic distortion and upper end smoothness, the AE woofers did very well, and were consistent between two samples.
Is the AE woofer better than the JBL? It is an excellent woofer, made by passionate people. It is impressive, and it's cool looking too. Does it embarrass the JBL? Is it a hand-down better woofer? No. The JBL parts are very good too. Which speakers do I personally like better, my three π's or my four π's? Both sound great, and they look so cool. Let's see, do I want to drive a 930 or a 308 today?...
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| Re: three π / four π comparison [message #63251 is a reply to message #63250] |
Thu, 24 June 2010 11:55 |
spkrman57
Messages: 522
Registered: May 2009
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Illuminati (1st Degree) |
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I think you did a very good job of comparing things Wayne!
I would have to say after much reading and hearing JBL 2226's and hearing a TD15X at Detroit AKfest (Cosmos speakers) that with the decline of availability of JBL drivers (no longer manufactured in the US as of Apr 2010), the Lambda's will probably be the easiest to obtain in the near future.
I thought the TD15X sounded a lot like a 2226. It takes a larger cabinet, but the sound was very similiar to my ears.
The TD15M is more efficient, but is closer to a Altec 416 driver and I'm not a fan of floppy surrounds on my drivers.
Ron
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| Electronic crossover [message #63254 is a reply to message #63252] |
Fri, 25 June 2010 10:26 |
spkrman57
Messages: 522
Registered: May 2009
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Illuminati (1st Degree) |
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| SteveBrown wrote on Thu, 24 June 2010 20:46 | You going to use an active crossover???
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Steve,
I plan on using the electronic crossover for a horn loaded 2-way in the future. I still have issues like getting a affordable preamp and finding a room to put them in.
Right now I have 2 systems in the living room that I'm working on at the moment. So the bi-amped system will most likely be upstairs with the corner horns (Jensen backloaded design).
Regards, Ron
PS: Tubino in Toldeo wants to borrow my crossover in the meantime for his 2-way system using TAD drivers.
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