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Multi-Way Conventional loudspeakers with crossovers

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Old 1st September 2008, 09:54 PM   #4421
KSTR is offline KSTR  Germany
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Michael's comments on flying speakers/drivers are spot on!

BTW, I once tried a completely baffleless dipole bass/sub, using one rubberstring-suspended 18" in the near field (about 70cm from behind). The best and cleanest bass I've ever heard, zero stored energy, perfect mechanical decoupling.

- Klaus
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Old 2nd September 2008, 05:11 AM   #4422
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Quote:
Originally posted by skorpion
As one cannot remember all written here, may be this is presented before: http://www.audiogon.com/cgi-bin/cls....ull&1225420119 .

/Erling
Looks like somebody over in the commercial sector has been reading this thread - note this quote from the Audiogon advertisement:

Quote:
We are really excited to introduce the Model 1 High Efficiency Planar. The Model 1 will debut officially at CES 2009 in Las Vegas, Venetian Hotel suite 31-215.

The Model 1 a large high efficiency 3-way dipolar loudspeaker using electro-dynamic drivers.

The design centers around a state of the art 12-inch mid driver with smooth roll off frequency response and active control of impedance (the 18sound 12NDA520), augmented by two large 15-inch woofers and a high quality 1-inch horn loaded compression tweeter (B&C DE250).

We selected the 12NDA520 after extensive listening to a number of 12-inch drivers like the Alnico Tone Tubby, vintage Altec 414 and Electrovoice SRO for example. We chose a 12-inch mid driver as we feel large drivers can better project large instruments like the piano or cello with realistic scale and weight.
Wonder where they could have gotten the idea to audition the 12NDA520, Alnico Tone Tubby, Altec 414, and EV SRO?

Better they pay the $25,000 to exhibit at the the CES than me.
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Old 2nd September 2008, 06:02 AM   #4423
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"We selected the 12NDA520 after extensive listening to a number of 12-inch drivers like the Alnico Tone Tubby, vintage Altec 414 and Electrovoice SRO for example."


The rising SPL on the 12NDA520 seems best for horn loading.
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Old 2nd September 2008, 06:45 AM   #4424
CLS is offline CLS  Taiwan
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Talking about the rising response, I found almost all of the 18sound's midranges, midbass, woofers are like this -- severely drop off from 500Hz and down. According to such FR graghs, their sound should be very lean and bass shy.

How do they sound in reality? I doubt the 100~200Hz range with 'only' about 90db/w is adequate for pro sound.
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Old 2nd September 2008, 07:26 AM   #4425
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More should use MJK's excellent software to simulate loudspeaker response with good resemblance of real life performance.

12NDA520 on the Audiogon baffle would perform like this without any crossovers applied: (courtesy MJK)

Click the image to open in full size.

18sound take very special response curves in their presentation evidently promoting special, rather small, enclosure sizes.

The issue is more about 12NDA520's cone breakup performance.

/Erling
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Old 2nd September 2008, 07:35 AM   #4426
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Default K&Q Sound Genesis LLC & Top Dog

This is great news! You just copy the efficiency figures of off the woofer data sheets and that`s it, your dipole is covering 36 to 20000 Hz (98 db, efficient as hell!) with ease! Now, Top Dog is a much better loudspeaker overall IMHO, it reproduces 35 to 21000 Hz and has above all +100dB efficiency!!! Pure enlightenment!!!!!
Once I built a passive dipole (baffle width cca 50 cm) loudspeaker consisting of two Peerless SLS 12 units per channel, with a measured response down to 30 Hz in my room. It was a 3way with a ribbon tweeter (95 db eff) which had to be padded down about 15 dB! So I guess their efficiency was about 80 db and correspondingly needed quite a lot of "juice" from the partnering amp. It sounded great in the bass though. Years ago tried one Beyma SM 118 (18 inch) in a similar arrangement, needed lots of power too, but I guess it`s just me,
all other dipoles seem to be extraordinarily efficient.
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Old 2nd September 2008, 09:36 AM   #4427
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The rising response of the 12NDA520 would be easy to counter with a low value C across the inductor feeding that driver within the crossover; a parallel tuned series loss, with C value between 4.7uF and 22uF.
__________________________________________________

My jigsaw cutting event at the weekend produced this. The crossover component values are not yet tuned to 'voice' the system, but I already have excellent sound.

Click the image to open in full size.

(Click thumbnail, then click image for larger size.)


The test baffle before this had the fullrange driver at just 40" above floor level - the lowest I have had for decades - mistake - that position did not sound right, and it did not have anything to do with driver interactions. The reason - voices, trumpets etc. just do not sound right when *coming from a seated position* in a room. Now at 54" the sound is most satisfactory. This test piece is just a simple 6ft x 18" Contiboard panel, so I shall be adding another inch of wooden base height, also shallow side and rear frame supports.

Here the Beyma SM115-N and DeltaPro-18A bass drivers complement each other. The 15" provides upper bass attack and definition; the 18" realistic sounding depth and LF ambience. The Beyma does not have the raised peak so many other 15"ers have before roll-off, but does frequency double ( euphonically I persuade myself ! ) on an OB with 20Hz input. The Eminence is relatively dead from about 200Hz upwards which is just like having an extra section of crossover for free. Other Eminence 18"ers are more efficient, but might need more filtering too.

This project is a single amplifier (one ohm capable) design using my transformer based T-bass drive circuit, and is already sounding excellent, with cleaner/deeper bass than gained from any LS used here before - including low ABRs and subs, which as monopoles might might generate an impressively flat SPL response (as for organ music) yet still fail to accurately reproduce the leading edges of LF wavefronts (for drums) as can an OB!


Cheers ....... Graham.
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Old 2nd September 2008, 10:02 PM   #4428
Hennie is offline Hennie  South Africa
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Quote:
Originally posted by CLS
Talking about the rising response, I found almost all of the 18sound's midranges, midbass, woofers are like this -- severely drop off from 500Hz and down. According to such FR graghs, their sound should be very lean and bass shy.

How do they sound in reality? I doubt the 100~200Hz range with 'only' about 90db/w is adequate for pro sound.
18 Sound's measurements are done on practical enclosures in a free field (4pi) environment, so the 6dB drop-off below ~ 500Hz is the result of the so-called "baffle step". Other drivers would show a similar drop-off under the same conditions. Some manufacturers provide measurements for "half free field" conditions (2pi), therefore the "baffle step" does not show.
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Old 4th September 2008, 08:17 PM   #4429
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Quote:
Originally posted by skorpion
As one cannot remember all written here, may be this is presented before: http://www.audiogon.com/cgi-bin/cls....ull&1225420119 .

/Erling
Is it likely that these actually COULD be powered to high levels in reasonably sized rooms with low wattage SET amps (say, 8w/ch)?

Perhaps a SET on top and something with more oomph on the bottom?
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Old 4th September 2008, 08:19 PM   #4430
Anglo is offline Anglo  Canada
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Quote:
Originally posted by Lynn Olson


Looks like somebody over in the commercial sector has been reading this thread - note this quote from the Audiogon advertisement:



Wonder where they could have gotten the idea to audition the 12NDA520, Alnico Tone Tubby, Altec 414, and EV SRO?

Better they pay the $25,000 to exhibit at the the CES than me.
Lynn

How do you feel about that?
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