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Multi-Way Conventional loudspeakers with crossovers

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Old 1st May 2007, 05:17 AM   #611
Steve M is offline Steve M  Australia
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Jeff Mai: If the Yamaha compression driver you are talking about is the JA4281B, have you tried using it *without* the front compression plate? Sounds fantastic to me that way in a domestic situation. While maybe not as even and flat sounding they are much more airy, dynamic and thrilling with the plate removed.

I have a theory that since almost all compression drivers come from the pro sector, they are designed to handle high power and stay controlled at high volume (concert) levels - hence the need for a compression plate. Control at extreme volume levels is not necessarily a good thing in a home environment, where at lower volumes these drivers tend to sound a bit recessed. If you like to listen REAL LOUD keep the plates on, but at normal household levels removing the compression plate frees them up considerably, IMO.

Doing this however, turns them into a ring radiator rather than a compression driver.

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Steve M.
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Old 1st May 2007, 05:29 AM   #612
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Quote:
Originally posted by Steve M
Jeff Mai: If the Yamaha compression driver you are talking about is the JA4281B, have you tried using it *without* the front compression plate?
I've seen those, but mine are JA6681B. The JA4281B are true tweeters with a built in horn, I believe. Are you speaking of removing the horn?
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Old 1st May 2007, 08:14 AM   #613
SunRa is offline SunRa  Romania
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Quote:
There are very nice things about the 6ND610 I keep thinking about. First the 102dB sensitivity (on baffle on the use-range, ie. down to 500Hz). While the 8" driver suffers a little less from compression at a certain power, the smaller driver is about 7dB (!) more sensitive. Second, the BL/Mms ratio is much higher on the smaller driver. Thirdly the voice coil diameter of the smaller driver is only 5mm smaller than that of the bigger one. And last but not least, the smaller driver goes up to 5Khz, while the bigger one only up to 2-2.5khz (as per datasheet recommendation), which 1) allows for a ribbon on its best range 2) puts the crossover point further away from the ears most sensitive range.

Well, I keep wondering about that too. However, take a carefull look at these guys too: Precision Devices

The 8" line is very intersting, with all the drivers having a very nice response from 70Hz to 4.5-5Khz. Besides that, even the ferrite magnets ones have a BL of 11.5 or more. The problem is the low SPL (around 94dB), the neo versions being the most sensitive. However, I find the FR plots are great and this is the main reason I've linked them here.. They are quite expensive though.

You can expect some other surprisez from the rest of the speakers there. I guess this one is my favourite for a project like this for now : 10" Neo . The specs are 80Hz-5Khz frequency range, 21.8 T/m Bl factor, 99dB SPL, 2.5" voice coil.

The woofers are having some great specs too. And as far as I remember, Precision Devices offers some distorsion specs too (maybe on request?).

Edit:

Ok, this one here is freakin' good, although I suspect it's based on the motor of the former: 12" PD midrange
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Old 1st May 2007, 08:31 AM   #614
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The Precision Devices PDN.12MH25 has sweet looking response curves, it should be good for midbass use. But - the Xmax is only 3 mm (total) - similar to the limited-excursion guitar speakers like the 12" Alnico Tone Tubby and the 12" Celestion Blue.

Note tiny wrinkles on the impedance curve at 700 Hz, 1.4 kHz, 2.8 kHz, and 5.6 kHz. These are more significant than they look, they indicate energy storage at those frequencies, strong enough to be reflected as back-EMF to the amplifier. Possibly they are box modes of the unlined test box - would have been nice if the impedance was measured in free air, as per industry standard.
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Old 1st May 2007, 12:23 PM   #615
Pano is offline Pano  United States
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Quote:
Originally posted by jeff mai
I'd wager that the large format Altec system you heard with multicells was using a Hiraga crossover which uses a broad notch filter to address this issue.
Well the ones I heard certainly were, as they belonged to Jean Hiraga. He was kind enough to lend them to me several times. Great stuff. Westex driver (U.K. version of the 288) on 15 cell horns. Very, very good, indeed.

If the notch filter that Mr. Hiraga uses is the one shown here: Altec Thread, then the notch sims to a pretty gentle dip. There is a tilt up above 10K, to make up for the roll-off.

Big horns, big drivers don't sound like the little ones. Don't know if that helps much for a coax, though.
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Old 1st May 2007, 08:04 PM   #616
Pano is offline Pano  United States
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Here's your coax:
http://www.partsexpress.com/pe/showd...number=299-766

On sale now! It even has a horn.

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Old 1st May 2007, 09:36 PM   #617
Variac is offline Variac  United States
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Here's a thread discussing it:

coaxial

Of course Lynn hates a rectangular horn in front of the cone. Of course he's changed his mind ocasionally..

OTOH at that price you could have a lot of fun making your kid a PA system...
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Old 1st May 2007, 10:48 PM   #618
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Quote:
Originally posted by panomaniac
If the notch filter that Mr. Hiraga uses is the one shown here: Altec Thread, then the notch sims to a pretty gentle dip. There is a tilt up above 10K, to make up for the roll-off.
That's the one. Mine is slightly different from the 16 ohm version pictured:

R=24.9
L=9 mH - I've left out the 100 ohms series R
C=1 uF

The response I've seen for the Hiraga network shows a 6db / octave lift above 5kHz, but I haven't simulated it myself. I've simulated my network, and it shows a similar lift starting a little lower in the HF.
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Old 2nd May 2007, 01:54 AM   #619
Steve M is offline Steve M  Australia
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Hi Jeff,

No, the Yamaha 4281B is not a horn loaded driver. It is a compression tweeter with a thick front plate forming a concave chamber in front of the diaphragm and the sound is 'squeezed' out of a 15mm hole in the plate. Anyway, to me in a domestic situation it sounds better with the compression plate removed.

Regards,

Steve M.
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Old 2nd May 2007, 04:15 AM   #620
fiacono is offline fiacono  Australia
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Tone tubby has released a FR curve on their new 8" driver.
Maybe they will do the same for their new 15" Super Boy bass.
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