Beyond the Ariel

[dobias]

Gentlemen,
I'm intrigued with PE's latest sales special of Lanzar Max12" dual coil subwoofers :
non pressed paper cone
4 ohms per coil (I'd wire them for 8 ohms)
VCdia: 2"
Xmax:10mm
Fs: 33
SPL: 88dB (their single 4 ohm coil model goes to 92 dB)
Qts: 0.47
Magnet weight: 130 oz.
Please give me your opinions about these before I order any. I would only use them up to a max of 300Hz.
dobias

[dude007]

Will Lynns new design work in a smaller 12 ft by 17 ft room do you think?

The room is dedicated so I can treat it however I want.

.

[Variac]

I like the way you are thinking these days Lynn, although you are getting into 4-way territory here. It was appealing to use multiples of the same driver rolled off at different frequencies, and still is a concept worth exploring, but it is becoming clear why it generally isn't done that way. I think that the high output required, combined with t he open baffle is the main reason it is beginning to look like it won't be the best approach.

On the other hand, to get the kind of output that you are talking about, 4 ways are not unusual in the pro world, so I guess not a surprise.

No matter whether you choose 6" 10", or 12" drivers of course there is no way to be sure that you have chosen the right drivers for you until you have listened to them

What is nice is that we know of various appealing, but very different candidates, including 18 Sound, Alnico Tone Tubbies, Behma, etc, - about 4 drivers really need to be auditioned for each size. Then for the tweeter, you have the RAAL ribbon and 2 or 3 different 1" compression drivers.

Then you are done!! So, I think that your first effort will really be a test mule, and your huge contribution to DIY will be to ferret out your favorite drivers. I suspect that some manufacturers will send some "loaners" or give you a good price. The ones you buy and don't use can surely be sold as they will all be desirable units.

[dmason]

I would be very surprised if John Harrison at Tone Tubby didnt... these dyed in the wool rockers have become fascinated by the audio DIY interest in their stuff. They are responding accordingly, and have several new drivers in the works. The 8 inch guitar cone, sadly with mud magnetics, but the FR curve, Fs/50, Qts/.70, and reasonable SPL/93db also look really good for scaled down iterations' midband driver.

Lynn, if you approached John or Charlie, they would put you onto one Jason Scheuner, who is their "speaker guy" and you could have a new collaboration, right there. Just thinking out loud here. I have spoken at length with Jason, very energetic, and interested in expanding and advancing the HempTone thang...

[Salas]

I just came back from the Athens High End show, and I could not help but remembering Lynn. What he said about nothing being built around the concept of reproducing real sound as experienced in a hall. Just experiments on mega luxury is all I saw and heard. Commercial expensive sound has nothing to do with music. Thank God we can still wield a soldering iron and a screwdriver in this neck of woods.

[chrismercurio]

I seem to remember an early proposed configuration by someone that used 4 side firing woofers. Can anyone point me back to that? I'm trying to avoid rereading the first 50 pages to find it.

I'm wondering if a U shaped open baffle speaker has 16" deep sides and an 8" baffle if the effective baffle length is 40"? and how the bass performance is affected by side firing a pair of 12" woofers on each side? I know the "nulls" would be facing the lstening position but also know that the polar response in the bottom octaves isn't as affected as much as the midrange. Thoughts? I have already read John K's and SL publishings on the U frame dipoles and just wanted to hear a few people weigh in. I attached a pic in case my english isn't clear.

Thanks,

C

[mige0]

Hi

Originally posted by Lynn Olson
And more thanks to Mige0 for the links to the Prodance site with extensive MLSSA CSD and Theile/Small measurements.

.....

Good information here! Thanks again!

Lynn, know you don't like EV and I agree on that they can be brute, but for me the EVL 12S_OEM is a speaker with most beautiful looking CSD out of that list.
Should go down to 120 Hz at 110 dB with no problem and also has an exceptional "drive" number though performing not so hot in Qms.

Greetings
Michael

[Lynn Olson]

The EV 12S_OEM has a big peak at 2.6 kHz (probably easily notch-filtered) and a low Qts of 0.23. Kind of wonder how different this would be from the 18Sound 12NDA520 - too bad we don't have CSD's of these drivers.

[Lynn Olson]

Originally posted by chrismercurio
I seem to remember an early proposed configuration by someone that used 4 side firing woofers. Can anyone point me back to that? I'm trying to avoid rereading the first 50 pages to find it.

I'm wondering if a U shaped open baffle speaker has 16" deep sides and an 8" baffle if the effective baffle length is 40"? and how the bass performance is affected by side firing a pair of 12" woofers on each side? I know the "nulls" would be facing the lstening position but also know that the polar response in the bottom octaves isn't as affected as much as the midrange. Thoughts? I have already read John K's and SL publishings on the U frame dipoles and just wanted to hear a few people weigh in. I attached a pic in case my english isn't clear.

Thanks,

C

OK for subwoofers with sharp lowpass filtering, but using through the midrange (as drawn) would be problematical. Note the magnets of the drivers are facing each other - this is a good technique for vibration cancellation (which is why we see this configuration using in closed-box woofer arrays with rods connecting the woofers to each other).

However, in a conventional closed-box configuration, this array is typically used in a 3 or 4-way system, since the tall, narrow box is prone to severe internal standing-wave modes, and off-axis listeners hear two arrivals, one for the left, and another for the right array of woofers. A sharp-cut lowpass filter reduces audibility of the box modes as well as the differential arrival times of the wavefronts from the L and R woofer arrays.

Keep in mind diaphragms are acoustically transparent, so you can "see" one driver through another. This is why Isobarik alignments must be aggressivly lowpass filtered, otherwise the cavity between the two woofers not only has non-coincident arrivals from the front and rear drivers, but standing waves formed by the cavity itself. (With no drivers mounted in it at all, an Isobarik would form a resonant cavity.)

U and H-baffles are partway back to closed-boxes in terms of standing-wave colorations, thus the requirement for lowpass filtering to minimize coloration. Moreover, the lowpass filtering has to be well below midrange frequencies, since the 300~600 Hz range is exactly where conventional closed-boxes suffer the most from standing waves (due to poor absorption of readily available damping materials at lower frequencies).

As mentioned earlier, I am not as interested in a particular polar pattern (dipole, quasicardioid, controlled 90-degree dispersion) as I am in the intrinsic sonics of the drivers themselves. I probably have a less charitable view of driver and cabinet sonics than many of my contemporaries - I'm looking for the handful of current-production drivers with low coloration, large dynamics, and low IM distortion.

These drivers are scarce, especially since I don't have the luxury of being an OEM that can pre-order several thousand custom models of prosound drivers. Rest assured that 18Sound, BMS, B&C, Beyma, Tone Tubby, Radian, et al make many OEM versions we don't get to see in the catalogs. These are proprietary, secret, we ain't gonna hear about these - and if we do, we can't buy them anyway, so no point in pursuing the matter.

So in the restricted universe we have, no unobtanium out-of-production drivers, no OEM versions, good CSD and IM distortion measurements by audiophile and professional standards, and - oh yes - it would be nice if they sounded good too.

[Variac]

current-production drivers

excellent...stay the course!