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Multi-Way Conventional loudspeakers with crossovers

Beyond the Ariel
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Old 12th November 2013, 08:13 AM   #9701
boldname is offline boldname
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Originally Posted by g3dahl View Post
I'm actually quite happy with the HF shape of the beryllium version, which looks to be well-suited for extending with either a ribbon or AMT. I understand that a significant amount of the aluminum diaphragm's top-end energy consists of ringing, and I'd rather do without that.

Even without optimization, the combination of the Aurum Cantus G3 ribbons sounded very promising with the beryllium drivers. I had tried the ribbons with the regular 745's, but the 745's sounded better on their own.

It could very well be that the neodymium 745 with aluminum diaphragm would be a nice compromise for use without a tweeter (Lynn liked it a lot), but I must admit that I like the idea of having wider dispersion at the top end.
Yeah I guess that is a fair statement. And if one goes with the Al Neo version it will take the Be version as an upgrade if the safer lower cost route shows it is a soiund one likes personally. Read that the the Neo motor is the same for Al and Be. Is that the consensus.

Trouble for me is I have a very good direct driver system at present and my target is to beat that. Perhaps we are all much in that position
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Old 12th November 2013, 08:47 AM   #9702
soongsc is offline soongsc  Taiwan
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Originally Posted by g3dahl View Post
Did some measurements of the Radian 745 NEO/beryllium today. Here's what I have so far:

Click the image to open in full size.

This measurement was taken with no crossover or equalization…just the driver on the Azurahorn AH-425. Drive level is arbitrary.

Below it appears with an overlay of the regular 745 driver, with ferrite magnet and aluminum diaphragm.

Click the image to open in full size.
Looks like the new diaphragm gives a,very nice roll off.
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Old 12th November 2013, 11:21 AM   #9703
PierreQuiRoule is offline PierreQuiRoule  Canada
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Originally Posted by soongsc View Post
Looks like the new diaphragm gives a,very nice roll off.
Indeed. It is interesting to compare with the charts on post #9320 where the Truextant diaphragm in a JBL driver yields a similar roll off. Nice.

Many thanks to Gary for posting these and sharing listening impressions.

Pierre
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Old 12th November 2013, 11:30 AM   #9704
PierreQuiRoule is offline PierreQuiRoule  Canada
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Lynn could you kindly give me the contact details for Truetone so I can order.
Boldname, I sent you a private message.
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Old 12th November 2013, 02:14 PM   #9705
Kindhornman is offline Kindhornman  United States
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Those graphs of the earlier aluminum ceramic driver look like they still have the 16khz resonant peak in them. That driver would have a real problem being flattened and giving a smooth top end and this was what I was talking about earlier, that peak is not musical in nature but a resonant problem with the combination of driver and diaphragm. Try and notch out that much resonant information and by the time you are done you have lost the top octave of useable range.

With the Be model you could at least use a slope in the network to flatten the top two octaves without having a large peak in the upper response curve. That to me is a major advantage and it looks like the mechanical resonant problem has been taken care of. It would however be interesting to see the Be driver with an aluminum diaphragm to see how much is just the difference between the breakup modes of the two different materials in the top octave.
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Old 12th November 2013, 02:36 PM   #9706
g3dahl is offline g3dahl  United States
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Hi The website does show but it not active. I had tried everything on there. Please try it and see.
It does work from my end; I looked around on the site to make sure before posting the link. Doggone web browsers…I have no idea.

I am sending you a PM with Martin's email address.
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Old 12th November 2013, 03:08 PM   #9707
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Those graphs of the earlier aluminum ceramic driver look like they still have the 16khz resonant peak in them. That driver would have a real problem being flattened and giving a smooth top end and this was what I was talking about earlier, that peak is not musical in nature but a resonant problem with the combination of driver and diaphragm. Try and notch out that much resonant information and by the time you are done you have lost the top octave of useable range.

With the Be model you could at least use a slope in the network to flatten the top two octaves without having a large peak in the upper response curve. That to me is a major advantage and it looks like the mechanical resonant problem has been taken care of. It would however be interesting to see the Be driver with an aluminum diaphragm to see how much is just the difference between the breakup modes of the two different materials in the top octave.

There is a dip around 2 - 3 kHz that is not on the ceramic/Al driver which appears better at 8 - 10 kHz just looking at the graph. Or is this spurious

Thought the Neo driver for the Al Neo would take the Be diaphragm as a replacement and is the same driver. I think there are new Be diaphragms retrofittable for at least, most of the range.

Any body got a different take on this.

Last edited by boldname; 12th November 2013 at 03:11 PM.
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Old 12th November 2013, 03:26 PM   #9708
Kindhornman is offline Kindhornman  United States
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Boldname,
I am going to assume for right now with no evidence that if you took the graph of the Be driver and went out past 20khz about 22khz or close you will again start to see some diaphragm breakup in the response curve like you are seeing at 16khz with the al diaphragm. The graph just shifts to the right with the beryllium. This also shifts those nasty areas up out of the pass band while the 16khz is right in the top of the band.
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Old 12th November 2013, 05:44 PM   #9709
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Boldname,
I am going to assume for right now with no evidence that if you took the graph of the Be driver and went out past 20khz about 22khz or close you will again start to see some diaphragm breakup in the response curve like you are seeing at 16khz with the al diaphragm. The graph just shifts to the right with the beryllium. This also shifts those nasty areas up out of the pass band while the 16khz is right in the top of the band.
It would be good to see some other tests esp pulse and step tests to see how the stored energy dissipates for Be and Al with the Neo driver.

I wonder at what dB level the Be and Al begin to close up a bit. So often when a Be direct driver is brought out it is often unremarkable as it is almost academic ,unless it audibly modulates with the lower frequencies. The enforced treble roll off by the horn geometry is often a great saviour
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Old 12th November 2013, 07:04 PM   #9710
Lynn Olson is offline Lynn Olson  United States
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The HF breakups are not a single resonance, but a group of chaotic modes spanning most of an octave. A notch filter would not be effective, and I doubt that DSP could correct it either. Remember, both the horn and phase plug rely on uniform velocity across the entire diaphragm to operate correctly; some phase plugs suppress the first diaphragm mode by careful spacing of the slits, but have no effect on higher-order modes.

The narrowing directivity of the LeCleac'h can be exploited by listening to them off-axis, but I found that only slightly off-axis was desirable, maybe about 5 degrees or so. I aimed them at a point about 1 foot/30cm in front of the listener; you could see about half of the throat of the horn from the listening position.

Many readers may think that the hassle of supertweeter isn't worth it; well, the tradeoff is the lower limit of the MF/HF horn. Are you OK with a crossover between 1 to 1.5 kHz? That's what small-format demands. That, in turn, either implies a mid horn 40"/1 meter across, or 10 to 12-inch direct-radiators.

In the Summa loudspeaker, Dr. Geddes utilizes the first mode of his 15" driver as part of the 950 Hz electroacoustic lowpass filter for the woofer, and takes the small-format Mylar-film compression driver just slightly below the lowest recommended crossover frequency. So a small-format compression driver can be combined with a 15" direct-radiator, it's just a path I didn't want to go down myself. I wanted a bit more spectral room between the LF and MF/HF, and this almost forces using large-format compression drivers, or the driver selection mentioned in the previous paragraph.

Boldname, you mentioned being satisfied with your direct radiator system. That's how I feel about the Ariels. I've had them for 20 years now, and still like them better than anything I heard at the RMAF show, or the CES in Las Vegas. There were one or two speakers at the show were about equals, but I was very pleased to listen to my own system after the show. For the last three years, my RMAF guests have liked it as well.

The main driver for the new loudspeaker is owning direct-heated triode amplifiers, which have power outputs in the 3 to 20-watt range. I am not going back to transistors, in Class A, Class AB, or Class D. 20 watts is adequate for the 92 dB/meter/watt Ariels, but only adequate. More headroom would be nice, but not at the expense of the quality I already have. That has been the primary goal all along.

Well, it turns out that a true 92 dB/meter/watt is pretty close to the upper bound of direct-radiator tweeters. You can get slightly more, but only just a little bit. The Ariel II would have been only slightly more efficient, and I'm not even sure modern drivers are any better than what I was using twenty years ago.

So the search has been for a horn that doesn't sound like a horn, but retains horn dynamics and vividness of tone colors. I'm not talking about always-there, additive coloration, but the capability of playing tone colors when they're present in the source.

I should mention that Gary Dahl has very critical ears; he finds the sound of most high-end equipment unsuited for classical music. I can only agree. Most of it mangles beyond recognition the sound of live symphony orchestra, to the point where most recordings are unlistenable and not enjoyable at all. Unlike the claim relentlessly pushed in the magazines and audiophile websites, mainstream high-end equipment isn't "accurate" in any sense, it is grotesquely inaccurate, and has the same relation to reality that a horror movie does to the real world. Based on what I hear in the hifi shops, RMAF, and the CES, less than 5% of the equipment on the market is suitable for music of acoustic origin. I enjoy the social aspects of the shows (very much), but the sound in most of the rooms is horrific, far worse than a table radio or car stereo. I have no idea why the taste in the high-end is so debased.

It also means I can't honestly answer queries about "what does this or that sound like" because my tastes don't accord with most of the industry. Gary Dahl, Gary Pimm, John Atwood and I share similar tastes, but I have no idea what most audiophiles enjoy. I've sat alongside audiophiles with checklists of subjective qualities, carefully ticking each box as they listen to a room at the RMAF, but to me it's either good or bad, with not much in between.

Last edited by Lynn Olson; 12th November 2013 at 07:34 PM.
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