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Multi-Way Conventional loudspeakers with crossovers

Unbaffled Dipole
Unbaffled Dipole
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Old 10th February 2010, 10:56 AM   #11
keyser is offline keyser  Netherlands
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At the moment I'm using a combination of EQ on individual drivers and global EQ. I have done this all manually, but doing it from the computer seems a much easier way.

Tuning mainly by ear can lead to good results, but the combination of listening and measurements gets you there a lot quicker!
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Old 10th February 2010, 11:06 AM   #12
StigErik is offline StigErik  Norway
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Ok, you seem to be knowing what you're doing here! I usually do a combination of individual and global EQ as well. I dial it all flat and nice by measurement, and then adjust the global EQ to taste, mainly by listening. Sometimes I assist with measurements just to check if I'm not too far off, or if there's something wrong I dont quite catch only by adjusting EQ based on listening.
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Old 10th February 2010, 02:23 PM   #13
Saurav is offline Saurav
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It's interesting to see these designs that are somewhat similar in concept Here's what mine currently looks like:

Unbaffled Dipole-12-jpg

Unbaffled Dipole-13-jpg

I don't have saved measurements of the full system yet, and I'm still playing with the crossover. Drivers are B&G Neo3PDRW, Audax PR170M0, AE OB12, crossover is a DCX. The bare PDR has a diffraction null around 7kHz that I need to try and address with foam, and I also need to think about how to move the tweeter back to better align it with the midrange acoustic center.
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Old 10th February 2010, 02:31 PM   #14
Saurav is offline Saurav
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Actually, I have some measurements I can share:

'Nude' Neo3PDRW:

Unbaffled Dipole-bare-neo3-jpg

The full system polars from an earlier version. The bass drops off due to the gating. I didn't try to boost the 7kHz null, since that'll make the off-axis worse. I'll play with foam / felt and see what I can do. I think I ended up dropping the tweeter level 1-2dB after listening to this for a while.

Unbaffled Dipole-system-jpg

And the power average of the previous measurements:

Unbaffled Dipole-power-average-jpg
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Old 11th February 2010, 05:25 AM   #15
Valentino is offline Valentino  Norway
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Nice work, keyser. I like the looks too.
And StigErik, if you have some measurements of my concoctions lying somewhere, please post.
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Old 11th February 2010, 10:04 AM   #16
keyser is offline keyser  Netherlands
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Saurav,

Looking good! Your plots show a small off-axis bump between 1 and 2 khz. The tweeter seems to be at blame. All in all you've been able to maintain CD from midrange to tweeter very well, though! Counting the number of curves in each plot I haven't been able to make sure which curve represents which angle. Would you please clarify?

Saturday I'll probably be in the opportunity to compare the Neo3W to the Neo3PDR. The Neo3W was chosen for this project because simulations indicated there would be less diffraction at high frequencies due to beaming of the tweeter. I reckoned I'd sacrifice top-octave response for smoother dispersion below 10 khz. In your plots the diffraction starting around 6 khz looks not much worse than the diffraction I'm measuring with the Neo3W. It's probably worth to investigate.
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Old 11th February 2010, 11:36 AM   #17
gainphile is offline gainphile  Australia
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Excellent polar response! Please let us know which Neo is "best" after the experiments!

Having back-to-back dome tweeters is a love & hate relationship, and they couldn't produce something like your plots
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Old 11th February 2010, 01:12 PM   #18
keyser is offline keyser  Netherlands
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I can understand the 'hate'-part when it comes to tot back-to-back dome tweeters, but I honestly don't understand why so many people still persist in using dual domes. Going that route was never seriously considered for my project, as there are too many complications without any apparent advantage over a dipole tweeter. Especially when a wonderful tweeter such as the Neo's can be had for only $40.

By the way, if there are more people now finding unbaffled dipoles to be the next step in the dipole evolution, why are people like Siegfried Linkwitz and John Kreskovsky not picking up the concept?
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Old 11th February 2010, 01:26 PM   #19
gainphile is offline gainphile  Australia
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From what I read in linkwitzlab forum, it seems to have something to do with target SPL of 120db. Even with domes only few qualifies such as the millenium.

But I don't listen that loud.
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Old 11th February 2010, 01:28 PM   #20
StigErik is offline StigErik  Norway
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I agree that unbaffled dipoles is the "next step" compared to the traditional wide baffles, but an other step from unbaffled is to fully suspend the drivers. The means no small baffles, no mouting brackets, just hang the drivers in wire. Believe me - there is a lot to gain in sound quality by suspending the drivers this way.
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