Beyond the Ariel

[ro9397]

Originally posted by riff.ca
...Lynn:...Two thinks I suspected are, I believe, confirmed. 1) We have almost no idea how important time alignment is. 2) Any attempt at absolute time align is compromised at best.

The link to your site provided lots of interesting reading. I especially enjoyed the short history of hi-fi. Interesting how audio consumers have been lead around by the nose going exactly where the big money players want us. I've been in the same position you mention auditioning a SS amp with a group and being the only one who thought it was horrid! That was years ago and it was kind of lonely. I realized much later that a pair of La Scalas and a Crown DC-300A drove me away from listening to recorded music for several years. During the same time period there was a serious push to sell SS to guitarists. Thankfully I have no memory of a group of players raving over the latest SS turd. [/B]

Especially the last sentence above is among the most succint analysis of high-end audio I've read. The very latest $5500/pr USD MSRP Esoteric MG-10 standmount all-magnesium monitor is among the most awful speakers I've heard...made by Europe's Tannoy for Japanese Esoteric...Tannoy has made some gems in the distant past but this latest is NO gem.

[SamL]

Originally posted by ScottG



http://www.nutshellhifi.com/MLS/MLS6.html

From the link.

I'm told by Gary Pimm the small notch at 2.9 kHz (and 5.8kHz) is actually a reflection off the stamped-frame basket, and gluing 3/8" felt pads on the inside of the frame gets rid of it completely. This leaves the 4 to 5 dB elevated region between 1.5 and 5 kHz, which is pretty simple to equalize with a simple rolloff or shelf filter.

I wonder if the same for the 2K peak on Eminence Lil' Buddy. This will be an easy fix.

[Lynn Olson]

Originally posted by dmason
My own uninformed opinion as to why the Emerald Physics OB offering was so well received is because there were a ton of people who had never heard a reasonably well executed FULL RANGE open baffle set up. Most of the people commenting were high dog, monkey coffin listeners, and those, sound nothing like OB. Second, the Emerald is about the only commercial offering I can think of that addressed employing open baffle response for the lower register/bass in the design; the Bastanis had similar approbation at these shows, but is in my mind, an essentially flawed design in that it uses sealed drivers for bass. The money zone in OB sonics is <1500Hz, as anyone whom has heard this likely will readily agree.

I also suspect "a" reason for the permanent, sealed opaque grilles is to obscure the fact that they are using some very inexpensive Eminence Alpha 15, and the bottom of the line BMS compression driver. What amazes me is the fact that the entire proceedings are dimmed and damaged by the Behringer active crossover these things are controlled by.

While I wish Emerald Physics all the success they deserve with their efforts, what makes this particular thread most interesting to me is that over time we will come up with permutations in design that should completely SLAY this arguably flawed commercial offering. Keeping the crossover away from the critical midband might be one start. When I heard the Emerald, I immediately preferred the presentation of the "DarkStar" if for no other reason that that it avoided any tampering between 200-10KHz. www.thuneau.com

I was pretty disappointed by the Emerald's at the RMAF. Maybe they sounded a lot better at the previous year's show - it seems like a very different speaker than the one they first demo'ed. It didn't help there was no functioning CD player, so the music was restricted to the very audiophile-oriented stuff on the hard disk - you know, the inevitable ultra-close-miked blues recording recorded in a closet, a very over-EQ'ed and heavily compressed rock recording, all-digital - feh. Not easy to make any assessments with hifi store demo material.

The system itself sounded very over-EQ'ed, with an unnatural frequency balance and no sense of depth, perspective, or stage ambience at all. Dynamics weren't as good I was hoping it would be - the HF was pretty harsh and strained much of the time, and the mids were murky. Combining a big 15" driver with a little small-format horn tweeter is not going to be easy to do, even with 24 dB/octave crossovers - both drivers are working at the absolute edge of the working range, and it sounded it.

If the speaker had a proper midrange that would have made all the difference - the 15-inchers could have been dumped around 200~300 Hz, and the 1" compression driver could have been crossed at 2.5 kHz or higher. The PR170 or any number of other pro mids would have been the obvious choice, and the system would have required much less EQ than it must have had. Much more headroom, better imaging, more relaxed sound, and much clearer midrange.

I honestly don't know why they tried to combine a very mundane-sounding Eminence 15" driver with a small-format plastic-diaphragm compression driver - any way you look at it, there's going to be at least an octave where things aren't working very well. Worst of all, this octave is going to fall right in the middle of the spectrum.

My favorite of all the speakers at the show was the AudioKinesis - and in a very difficult room, too. I very much enjoyed listening to my Mercury "Picture at an Exhibition" disc at Row 15 playback levels - this is a CD that is nearly unplayable on most hifi systems due to the extreme slewing requirements on DAC converters, amplifiers, and speakers. The contrast between the bottom-dollar Eminence woofers in the Emerald Physics and the pair of Alnico 10" TADs in the AudioKinesis was nothing less than stunning - yes, drivers matter!

You can't add Quality by turning a knob on the equalizer!

P.S. My 18Sound 6ND410's, 12NDA520's, and a pair of XT1464 waveguides arrived today! Oo la la! Now these are nice-looking drivers, with near-JBL/TAD build quality. They really look beautiful with the curvy cast-aluminum frames and sophisticated ventilation systems. Cones in both the 6ND410 and 12NDA520 are very stiff and light.

The medium-format XT1464's, by the way, DON'T have the "pinch" in the throat that the 1" format horns do - and the black plastic has a very smooth, polished finish on the inside of the waveguide. I hope they sound as nice as they look - time to contact the local woodworkers to get a test baffle built.

[SunRa]

P.S. My 18Sound 6ND410's, 12NDA520's, and a pair of XT1464 waveguides arrived today! Oo la la! Now these are nice-looking drivers, with near-JBL/TAD build quality. They really look beautiful with the curvy cast-aluminum frames and sophisticated ventilation systems. Cones in both the 6ND410 and 12NDA520 are very stiff and light.

This is geting exciting!

Good luck with your build! How's your health status?

[Lynn Olson]

Better by the day. The drivers are downstairs, where they'll be tested once I get the temporary baffles made.

[nullspace]

Originally posted by Lynn Olson


P.S. My 18Sound 6ND410's, 12NDA520's, and a pair of XT1464 waveguides arrived today!

...

The medium-format XT1464's, by the way, DON'T have the "pinch" in the throat that the 1" format horns do - and the black plastic has a very smooth, polished finish on the inside of the waveguide. I hope they sound as nice as they look....

Hi Lynn --

Would you mind elaborating on how the XT1464's made it onto your shopping list? I wouldn't have thought that you'd give a narrow coverage CD horn/ waveguide the time of day.

Regards,
John

[Lynn Olson]

Well, the Azurahorn AH-550 and Music Concrete horns are pretty expensive, although I'll probably be getting one or the other in the next month or two. I hope the rumours of them going out of production are not true - still haven't found anyone in the USA that makes wood Le Cleac'h profile horns (help!). The USA folks are all in love with Tractrix, exponential, or conical. Dunno what's up with that. Seems like hifi in this country is always behind the times for some reason.

I'm not as fixated on a certain size and shape of coverage pattern as the other horn enthusiasts. What I want is really good transient response with rapid decay - thus, no kinks in the profile, minimum mouth diffraction, and modern finite-element design methodology. I want the horn/waveguide to be good enough the time performance of the compression driver dominates, not the horn/wavguide.

The plastic (I think it's polycarbonate) XT1464 will be good enough for test measurements and probably audition - and a pair doesn't cost very much for experimentation. The Azurahorn and Music Concrete horns (with shipping to Colorado) are costly enough to be too expensive for just fooling around, although I'm quite sure I'll settle on one or the other. The XT1464's might end up serving as rear room-fill (pointed upwards and to the back) horns once I settle on the Le Cleac'h horns I want for the main speakers.

I don't much care for the sound of small-format (1") compression drivers, so my experiments will be confined to 1.4" (35mm) and possibly 2" format horns and compression drivers. Since the supertweeters are already on hand, there is no need for extreme performance beyond 7 kHz - which is good, because compression drivers and horns tend to fall apart at high frequencies anyway.

Diaphragms and surrounds go into resonance modes, phase plugs become inaccurate, the size of the throat is too large for the wavelengths involved, the horns loses its diaphragm loading, IM distortion starts to rise very rapidly, the pattern becomes lobey with many little spikes, HOM's (multipath) start to dominate, there are plenty of things going wrong from 7~10 kHz on up. This, conveniently enough, is where ribbons start to excel, with power requirements dropping off with frequency.)

Here is an interview with Doug Button of JBL, describing in great detail all the things that go wrong at HF - titanium enters the breakup region at 4 kHz (yes, really), aluminum at 7 kHz, and the most exotic beryllium (at $1399 per driver) gets into trouble at 15.5 kHz. The phase plugs aren't doing too well, either, with nonuniform wavefronts coming out of the slots, degrading the performance of the horn.

By direct radiator standards, this is pretty poor performance. So why use horns at all at the highest frequencies, unless it is a dedicated supertweeter?

The main argument against a supertweeter is when the horn mouths all have to be mounted on a common front panel, as in a soffit-mounted studio monitor. All this looks nice and neat and tidy, but the diaphragm for the supertweeter is then several wavelengths behind the diaphragm for the main mid/high horn - this is bad for the crossover and lateral dispersion. Thus the prejudice against supertweeters in professional studio-monitor applications, unless the whole system has digital delays to compensate for the path-length difference.

But none of that applies to this system. The horns and the supertweeter will be in free air, supported by a vertical stand, and the diaphragms will be time-aligned for the listening position. So a supertweeter makes a lot of sense as a simple way to avoid the short-wavelength trouble region for compression drivers, phase plugs, and horn/waveguides.

[nullspace]

Thanks for that Lynn. I'll be quite curious to hear your impression of the XT1464s once you get them up and running.

Regards,
John

[Carl_Huff]

Either I am incompetent or there is very little about Le Cleac'h profile horns on the web. What is the history and science behind it? Does anybody have a collection of good URLs? And where is the spreadsheet that I have read about that computes a Le Cleac'h profile? Where is that?

Somebody please help me muddle thru ...

Best Regards,
Carl Huff

[thomaseliot]

Originally posted by Carl_Huff
Either I am incompetent or there is very little about Le Cleac'h profile horns on the web. What is the history and science behind it? Does anybody have a collection of good URLs? And where is the spreadsheet that I have read about that computes a Le Cleac'h profile? Where is that?

Somebody please help me muddle thru ...

Best Regards,
Carl Huff

In french, but with links to spreadsheets

http://ndaviden.club.fr/pavillon/lecleah.html