Beyond the Ariel

[mige0]

Hi

ScottG I am not so much concerned about the "ALNICO sound" as it may balance nice with the otherwise low coloration concept (open baffle, hemp cone). No one knows until no one has tried! I had some nice experiences with this "ALNICO sound" from vintage gear as well.

What would keep me off from ALNICOs is reliability.

http://www.diyaudio.com/forums/showt...538#post605538
"http://www.diyaudio.com/forums/showthread.php?postid=605538#post605538"

This might not be an issue as long as you are with guitar combos but with an all passive design someone fires up with a high output amplifier it most likely is.

Great link to the Emerald's Nemesis!

Greetings Michael

[Salas]

Imagine what they would have said in Vegas if it was an XTA and not a DBX driving it...But you see...First things first and it still looks like it works great.

[happy.gringo]

How about the Ciare 12.00W1 for the mids? Qts is low, but how low will it need to play? It looks relatively smooth to me:

http://www.ciare.com/oem_new/pdf/12.00W1.pdf

[Pano]

Originally posted by Lynn Olson
At the time, all of their speaker-measurement graphs were showing 15.75 kHz artifacts ... I let them know they were getting broadcast TV signals in their microphone

???

That must have been a long time ago, if they ran monitors at 15.75 Khz. Or were they watching TV while they did the measurements?

FWIW, the scan rate of modern computer monitors is far beyond the audible range, up at 60Khz and above.

I used to be annoyed by the 15.75Khz whine of TVs. Not any more - that's an advantage of age. :P

[Lynn Olson]

Originally posted by panomaniac

That must have been a long time ago, if they ran monitors at 15.75 Khz. Or were they watching TV while they did the measurements?

FWIW, the scan rate of modern computer monitors is far beyond the audible range, up at 60Khz and above.

I used to be annoyed by the 15.75Khz whine of TVs. Not any more - that's an advantage of age. :P

Early MLSSA system, running DOS 3.2 through 6.0, on 286 and 386 PC's with the abomination of "expanded" memory (the ol' 640K brick wall of antique PC's). The earliest graphics were "Hercules" monochrome graphics and CGA color at 320 x 240. Very fuzzy, huge pixels, only four colors, the only merit CGA had was that it ran at the TV sync rate.

MLSSA was second-generation DOS/PC, thus supported better graphics (in fact, required them) and expanded memory models. My card is so old that it will NOT run on any ISA bus faster than 8 MHz - Gary Pimm and I tried, and we know that it WON'T work with a 8.25 MHz bus.

The current-generation MLSSA cards do run faster than 8 MHz, but still unfortunately require not only DOS, but an ISA bus - and how many years has it been since ISA was offered on any motherboard - hmm, maybe 250~333 MHz Pentium II vintage?

As for TV breakthrough, phantom-powered condenser instrumentation microphones are prone to RF interference. When I lived in Portland, we were about 15 miles from the transmitter towers, but I still had problems with television RFI intruding on the microphone. I know what TV sync buzz sounds like - a whirr that changes somewhat depending on picture content - and that's what I heard. If it's computer-monitor breakthrough, you're not going to hear the fluctuations that TV pictures have, with their constant scene changes and associated changes in the TV waveform (bright to dark transitions, for example).

What's really weird - and I have no explanation whatever for this - I can easily hear the horizontal sync whistle of 1080i HDTV! I shouldn't be able to hear this at all, it's around 35 kHz or so (the horizontal rate is a bit faster than 480P).

[Salas]

Originally posted by Lynn Olson

What's really weird - and I have no explanation whatever for this - I can easily hear the horizontal sync whistle of 1080i HDTV! I shouldn't be able to hear this at all, it's around 35 kHz or so (the horizontal rate is a bit faster than 480P).

Maybe you pick up some IM byproduct?

[Lynn Olson]

PaulW has posted a set of measurements of the 18Sound 12NDA520 driver in a small open baffle. Not perfectly flat, but usable, especially with a crossover at 1.2 kHz. Does make me wonder about a notch filter at 2 kHz, though, considering the CSD plot.

The real shocker is the SEAS W26 driver in the top two sets of measurements - high-Q resonances combined with low efficiency. Just to make things interesting, I'll bet the resonances are directional as well, which makes equalization pretty challenging.

For those considering a true 3-way instead of the 2.5 or 2.5.5 system I've been describing, the 18Sound 8NMB420 looks like a real charmer, with superb measurements. This driver could be used with a much higher crossover of at least 2.5 kHz, which in turn would open the door to a wide range of high-efficiency ribbon tweeters.

It's also a bit less efficient at 95.5 dB/metre, which also allows for a wider choice of tweeters. The only downside I see is that 8NMB420 is more of a midrange driver, although the linear Xmax of +/- 5.75 mm is nothing to sneeze at - that's quite good, and a lot better than the guitar speakers we've been discussing. Even so, if I were using this driver (and I might), I'd high-pass it around 160 to 250 Hz, just to keep the low-bass out and keep the driver in the linear region. I'd let the 12 or 15-inch driver below do the heavy lifting in the 200 Hz-and-lower region.

You can see I've playing with the avatar feature of the forum - the mysterious pix is looking up at the V2 rocket in the Deutsches Museum in Munich. The other avatar I'm considering is a slightly comical picture of me in India in 1991, sitting under a tree and looking the part of a guru.

[Pano]

Thanks for the info, Lynn. That's old stuff indeed. I did projected subtitles off an Apple IIe back in the mid 80s. Wonder what scan rate that was? Not high, for sure.

Originally posted by Lynn Olson
how many years has it been since ISA was offered on any motherboard - hmm, maybe 250~333 MHz Pentium II vintage?

Well... My home computer is a 450Mhz PII with an ISA slot. This message comes to you via that ISA slot and the ethernet card in it. A great old 1998 Micron that just won't quit. Also have 4 DOS machines at work that run ISA slots to drive Iris printers. So ISA lives!

I like the guru pic. Thought you were in Hawaii. The Dalai Lama was just here on Maui. He liked the Hawaiian leis, said the leis in India often had worms.

[swak]

PaulW measurements are very helpful. Seems the published 18Sound curves have no smoothing, which is a good thing to pre-select drivers reading at them.

The 8" driver Lynn mentioned is really nice: if it gets the same lift on the lower end from the baffle Pawl W used one might be able to come with no crossover (but the LP filter at 150-200). It has a 10 Tm BL and 14.9gm mms. The 6" I mentioned before (6ND410) has a higher BL (11.6) and a much lower moving mass (8.2 gms), but the radiating surface is a bit more than half of that from the 8 inch driver, and Xmax is less than half (2mm p-p). A good thing is that both drivers have a moderate price, while the 10" Paul measured costs twice more.

Considering the gain from a similar baffle as PaulW´s, the 6"er should be roughly flat to 500 Hz (due to its rising response) while the bigger 8"would be flat down to 300Hz.

Wouldn`t the 8" incher still have a small rise above 1Khz up to the crossover point?

Lynn, how important for you is the BL/ MMS ratio?

[Variac]

He says he tested the 10NDA520 not the 12, or am I confused?