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Multi-Way Conventional loudspeakers with crossovers

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Old 29th June 2009, 03:24 PM   #31
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Quote:
Originally posted by augerpro
Guess it just goes to show what modern FEM modeling can do accomplish.

All Lambda motors were hand drawn on a napkin, I have never modeled them actually. There were 2 parts to the design that interplayed with each other and canceled each other bad aspects I learned once I pushed them to their limits. One was the extreme extension of the steel pole as that height had not been done prior to that time, and the other was the extra thickness of the copper faraday sleeve/ring. By taking the pole piece out of the motor so far it lowered the B loss of the copper sleeve in the gap. A win win I learned especially once the voice coil and top plate were made taller to match.
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Old 29th June 2009, 03:26 PM   #32
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Originally posted by ScottG


He also needs to substantially increase the eff. of the driver - making more a of "mid" driver and less of a "bass" driver. (..or at least provide that as an option.)

Meeting those two requirements (alnico + eff.) and I think we would have a single driver winner.

All it takes is money.....................

It can be done BTW with a slight re-engineer of a couple things, but its an expensive big step to take as it requires some serious minimum orders for materials.
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Old 29th June 2009, 03:37 PM   #33
badman is offline badman  United States
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Quote:
Originally posted by nickmckinney



All it takes is money.....................

It can be done BTW with a slight re-engineer of a couple things, but its an expensive big step to take as it requires some serious minimum orders for materials.
Aw, c'mon, just slap a bucking magnet on there and whalah, problem solved
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Old 29th June 2009, 03:41 PM   #34
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Quote:
Originally posted by nickmckinney
All Lambda motors were hand drawn on a napkin, I have never modeled them actually.

I was referring to the Eminence and FaitalPRO woofers actually. They have quite linear and low distortion motors, but apparently don't have any shorting rings. Nothing special is said about the polepiece geometry either, but obviously they've been optimized pretty well.
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Old 29th June 2009, 07:48 PM   #35
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The TD12M looks really good, no question about it. There are some interesting aspects to Augerpro's testing, though ...

Look at the GPA/Altec 414 "multitone_500Hz_100dB" graphs and compare the region above 2 kHz to all the other drivers - both 12 and 15-inch sizes. Set aside the number (which is set by the loudest harmonics) and look at the high-order distortion spectra (above 2 kHz).

The Altec has surprisingly low high-order distortion in the frequency range where the ear is most sensitive to distortion. These HF artifacts are not affected by electrical low-pass filtering of the driver - the test stimulus has no content above 800 Hz, so everything above that is driver distortion + noise. Against expectation, it is better than the TD12M, and much better than the other 12" and 15" drivers.

414 Distortion

TD12M Distortion

It might be the underhung voice coil and/or the Alnico magnet which are responsible for the notably cleaner HF characteristic. There's your triode-distortion harmonic spectra right there. The other drivers have more "clutter" in the 2~5 kHz region, which reflects the presence of additional high-order IM distortion terms.

On the other hand, the AESpeakers TD12M has a much better LF distortion characteristic, as shown by the "tone_150Hz_100dB" graphic, which is most likely the result of the exceptionally good Le(x) of the TD12M. It walks away from all the other drivers below 300 Hz, and is really good above 300 Hz.

I'll be doing subjective listening of the 414/Alnico, TD12M, and the 18Sound 12NDA520, with a primary focus on naturalness of the midrange with solo voice and choral music. Although the nominal crossover is 800 Hz, I don't plan on slopes any steeper than 12 dB/octave, so the quality above 800 Hz remains important. This is the same philosophy as the Ariel - each driver has to be natural-sounding without high-slope filtering to reject breakup regions.

Other designers rely on digital and/or high-slope crossovers to get what they want, but that's not the sound I'm after.
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Old 29th June 2009, 08:13 PM   #36
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I tried to view some of the others but couldn't.

Check the TD12M vs the TD15M distortion and see what the differences are. Any difference should be entirely cone related. I always found the TD15M had a better mid/upper response (at least to my ears)
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Old 29th June 2009, 08:13 PM   #37
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Quote:
Originally posted by Lynn Olson
Look at the GPA/Altec 414 "multitone_500Hz_100dB" graphs and compare the region above 2 kHz to all the other drivers - both 12 and 15-inch sizes. Set aside the number (which is set by the loudest harmonics) and look at the high-order distortion spectra (above 2 kHz).

The Altec has surprisingly low high-order distortion in the frequency range where the ear is most sensitive to distortion. These HF artifacts are not affected by electrical low-pass filtering of the driver - the test stimulus has no content above 800 Hz, so everything above that is driver distortion + noise. Against expectation, it is better than the TD12M, an unexpected result.

I noticed that too last night. Very interesting. The GPA softparts are really exceptional in that response even in breakup is really smooth. I haven't seen any other drivers with a cone or surround that looks the GPA stuff. I wonder where they get them from? And the pole vents out through the dustcap. Weird.
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Old 29th June 2009, 08:15 PM   #38
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Quote:
Originally posted by nickmckinney
I tried to view some of the others but couldn't.

Check the TD12M vs the TD15M distortion and see what the differences are. Any difference should be entirely cone related. I always found the TD15M had a better mid/upper response (at least to my ears)
TD15X or TD15M? I haven't tested the TD15M yet, although I believe John should have one the way from a drop ship order by a forum member.

Why couldn't you view the others? Something I need to look at on my end?
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Old 29th June 2009, 08:38 PM   #39
badman is offline badman  United States
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Quote:
Originally posted by augerpro

And the pole vents out through the dustcap. Weird.

This seems to me to be a good idea. The short path to outside air rather than into the enclosure is a plus, and also, no tube is necessary with that design, which avoids a resonant member near the cone.
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Old 29th June 2009, 10:53 PM   #40
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Quote:
Originally posted by augerpro



I noticed that too last night. Very interesting. The GPA softparts are really exceptional in that response even in breakup is really smooth. I haven't seen any other drivers with a cone or surround that looks the GPA stuff. I wonder where they get them from? And the pole vents out through the dustcap. Weird.

The pole vents through the dustcap as they use a solid piece of steel for the top center pole piece (on top of the Alnico) This was common back in the day, most other drivers like this used a fully screened dustcap. Its either this or no dustcap (like our TD drivers)


Quote:
Originally posted by augerpro


TD15X or TD15M? I haven't tested the TD15M yet, although I believe John should have one the way from a drop ship order by a forum member.

Why couldn't you view the others? Something I need to look at on my end?

TD15M - also I guess thats the reason I didn't see it
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