Al K. done good, REAL GOOD

[D-MAN]

Got the custom ESN 600's (specific to the new woofers and BMS 4590's) last night.

Hooked them up and they are NEVER coming out of my system! I am slating the Selenium D305 and JBL 2404H's to the new free-standing cabinets along with the previous ES network.

The change was immediate and raised it up MORE than one level. It's a whole-new ballgame. The bass smoothed out and the entire soundstage moved back. The front (most forward) point of the soundstage is dirtectly between the speakers, there is NO "too forward" presentation, in other words. I think that "forward" presentation is indicative of an impedance mismatch in the network. If you experience that, then think about getting an upgrade.

Here's some pics of the stuff.

DM

[D-MAN]

Ain't this CUTE?! The high-frequency section with tweeter attenuator.

[D-MAN]

The BMS compared to the Selenium.

[D-MAN]

BMS on the cabinet. These things are boat anchors!

20+ lbs hanging off the back of the horn. This is a temporary setup, of course.

[sfogg]

Looks like fun!

What woofer are you running now? So you are still three way but with a co-axial driver on the mid-horn...correct?

BTW, based on your other post about different woofers how would this one look for a horn driver?

http://home.pacbell.net/lordpk/lambda/TD15H.html

Lambda Acoustics is gone but I think Acoustic Elegance bought them out and may be producing their woofers now.

"These things are boat anchors! 20+ lbs hanging off the back of the horn."

That ain't a boat anchor....

Shawn

[D-MAN]

Shawn,

The woofers are Eminence CB15's which are bass guitar drivers. Yup, still 3-way but only one horn on top.

I did not run the numbers on the TD15, but I have a cursory opinion on them -

The heavy cone tends to indicate that it would be best served as a direct radiator as a general rule of thumb. Horn drivers typically have a very light cone, as a matter of fact, the lighter the better. The other thing that puts me off a bit is the foam surround, these usually indicate a soft suspension, not particularily what one wants in a horn driver.

There are always exceptions to the rules, I know some use foam surrounds in horns with no complaints.

Other than that, the numbers look pretty good (by eyeball). But the clincher would be running the numbers to find the most efficient throat size, upper and lower frequency corners and Vb required. This will make or break it for a horn driver.

DM

[D-MAN]

Please allow me to babble incessantly and even further on my impression of the new lashup...

I'm sort of gushing, I hate to admit, but I have been diligently working on these things for going on 2-1/2 years now, and while I have consistently moved up a level or two at a time with various upgrades before, I regard this as a quantum leap in performance at really no more cost than what I had previously.

First, I was worried about "beaminess" with the BMS drivers and the horns that I am using (which we have all heard about). This proved to be a red herring - absolutely not a problem. I also was a little concerned that I needed the ability to attenuate the tweeter separately from the midrange (like with the JBL2404H). I was wrong there, too. These actually blow away the JBL. If I didn't have a possible use waiting for the JBL's - I'd sell them, hands down.

Listening to these, I actually cannot believe what I'm hearing (granted I have only had a few hours with them so far). The closest I can come to describing the effect is imagine the largest Magnepans sitting in a corner (that's a stretch!) with a soundstage as wiode as their separation and NO compression with clear, clean undeniably solid bass and more dynamics than you may ever need or want. Depth queues, soundstaging, transients, nuance, timbre, tonality, ambiance, whatever you want to call it, it is there in spades. Natural, unforced and realistic. Holographic, even. Never, EVER heard horns do this before. The closest I can think of is the BIG Maggies, but these are WAY better.

The transients are so sharp, quick and realistic that you worry about damaging your ears (it hurts so good), the imaging is rock-solid spot-on, the soundstage deep and extended well beyond the "front" wall of the room. It goes beyond the confines of the room. And all of this at 1/3 watt! I am positive that this is the finest audio that I have literally ever heard.

I did not have to adjust the room treatments what-so-ever. The high frequency units seem to better handle the less-than-adequate room without much problem; this is completely new to me, I have fussed with exact placement and angles of not only the horns but the treatments for months on end prior to the new lashup. Refreshing but suprising.

I listened to the new Sheryl Crow cd "Wildflower" (ok, but not a great recording), Amy Grant (recorded with accented high treble as a test of ear-piercing), Flim and the BB's "Big Notes", Steely Dan "Two Against Nature", etc. and I have truthfully never heard everything in such a coherent manner. It was a whole new experience.

As I mentioned before, the bass smoothed right out with the new xover and "moved back" into the soundstage but is solid and spacially well-defined. The particular "twangy" effect that some bass players apply to their bass is noticable and "alive" sounding. It's weird. If you were to imagine a shape for the bass, I would say "round" and "centered", if that makes any sense. It is an unmistakable "ball" or "mound" of bass firmly located in the center of the soundstage, not flying all over the place, ill-defined and such. You can hear the bass reflect in the recording space in some cases (the signal, not the room). Realistic.

Drums, rim-shots, triangles, wood blocks, cymbals, etc. blow me away. Striking. Just striking. Shining, even. Sparkling. All there.

Vocals - I wish I could see Sheryl Crow standing there between the speakers. Sounds like she's unmistakably right there- and she's CLOSE.

I wanted to actually see her, though. That's a dissapointment.

Donald Fagin - well, I guess there are certain people that we don't want to actually see standing between the speakers! But I've loved those guys since "Can't Buy a Thrill" came out when I was in high school.

It's all there. I guess that sums it up.

Thanks for bearing with me.

DM

[mikebse2a3]

D-MAN you have my interest!!! I will be following your impressions as time goes by.

The BMS4590 sure looks good from the specs. and from your description of the sound.

This info might have been posted before but I thought some might want to see the Technical Specs. and Measurements.

mike[]

bms-4590.pdf

[mikebse2a3]

Hey D-MAN forgot to ask if you don't mind where can we buy these and roughly how much do they cost.

mike[]

[D-MAN]

Thanks Mike. They thoroughly exceeded my expectations. In a cheap horn, too.

Wonder what they'd do in a pure tractrix? I'm eyeballing a Martinelli wood horn...

http://www.woodhorn.com/BMS/bms_compressiondrivers.htm

Attached is the frequency and impedance curves for the BMS 4590 in the P-Audio 4525 (90x40) 2" horn. Note that the horn actually dictates the response of the driver rather than the other way around, that is, the best driver is only as good as the horn it's in. However, I was quite suprised to find that this combination actually sounds as good as it does. I'm sold.

DM

[Al Klappenberger]

Guys,

I was surprised also at how well the off-axis frequency response looked. I am no expert on horns and such, but the throat on that horn is 2 inch diameter. The tweeter is built right into the same driver unit as the midrange but electrically seperate. It could be that the tweeter section acts like it's not using the big horn but rather has it's own dispersion scheme that is not bothered by the big 2 ich throat. The coaxial mounting of the two means the drivers are time algned, so there is no need for rapid slopes. I used a simple 2nd order network that inverts the phase 180 degrees between the two drivers. In theory you just invert the polarity of one driver and the two should be back in phase. Sure enough, response tests showed a dip connected in phase and flat response with one driver reversed. Pure "text book"!

One other interesting thing: That woofer driver is actually 10 Ohms in sereis with about 1.6 mHy. I designed the 600 Hz crossover to have a 1.6 mHy inductor at the output end that I left out. The speaker has a very flat resistive 10 Ohm impedance all the way to 20KHz.

Here's the woofer driver test box that was adjusted to equal the back chamber volume of the horn undergoing final inspection. It was too big, so I stuffed it full of base boards for my Universal network until it was right.

Al K.

[mikebse2a3]

Thanks for the woodhorn link D-MAN. Really Nice!!

For some reason I can't open giff file(I've ran into this problem before) to see the response you posted.

mike[]

[D-MAN]

Does it show on the message at all (I can see it, but that may not mean that all others can)?

P.S. Al, it looks like it was stuffed with cats! But seriously, folks, Al did a splendid job. I couldn't be more satisfied (except if it was free, maybe).

DM

[Al Klappenberger]

Dana,

NO, the box couldn't be stuffed until AFTER final inspection by the I.G. (Max)!

AL K.

[Marvel]

Dana,

What's the difference between the 4590 and the 4590P?

Looking good to btw.

Bruce

[sfogg]

Looks like the P has a passive crossover built in.

Shawn

[mikebse2a3]

Does it show on the message at all (I can see it, but that may not mean that all others can)?

P.S. Al, it looks like it was stuffed with cats! But seriously, folks, Al did a splendid job. I couldn't be more satisfied (except if it was free, maybe).

DM

Yes it does show up on the post but if I try to open it, my Window Picture and Fax Viewer opens with no picture. Maybe I don't have something setup correctly with my computer for gif files. It also want open with Adobe Photoshop. Computers!! love and hate them!

Anyway I was able to do a "capture picture" and printed it off. THANKS

I have to say D-MAN I have been very doubtfull of trying to cover the range of 400Hz to 20KHz with one driver due to diaphram mass rolloff problems and loss of transient response from diaphram mass at the higher frequencies. This coaxil design looks like just what was needed for a really good MOD option for the standard KHorn. The potential to improve the Vertical and Horizontal polar response and time response of the Midrange/Tweeter and the possible improvement that brings also with room/speaker interaction really has my interest up!

mike[]

[Dave in ABQ]

Great write up D-Man! I love the details in your description. I'm very happy that your one step closer to ultimate sonic bliss. []

Jee, I just got my pair of KHorns a month ago and I'm already dreaming of all the cool mods I can do to make them even better then they are now. You guys are an insperation. [8-|]

[djk]

I received a pair of BMS drivers for evaluation. I would place it just under the TAD 4001 and JBL 2440/375 level of resolution. In other words, good but still not on the same playing field of the Locanthi designed TAD and JBL drivers. The coaxial driver does produce very good low end and top end in terms of frequency response measurements. Bruce (Edgar)

Re: BMS
The JBL 2440 sounds better than the BMS 4591 in all ways to me when used above 500 cycles. The BMS loads a little better below that in big horns otherwise no contest. I also prefer the 2440 to 2441. The smaller BMS driver would be OK for a small two way or as a HF tweeter although it does roll off more than the BMS graphs indicate. The 2405's win here again, more extended and linear above 10K.

Not bad for 30 + year old technology!! Mike Bates

• 
  

"keep in mind that the factory xover is useless: It even has a region where MF and HF are out of phase...

if you manage to do a fitting xover it should work great though.

best,

lk4200

"

jweiss

quoting

Bill Woods (designer for Yorkville Sound) about the Neo magnet Coax Compression drivers "he felt they were rather harsh, probably due to the use of diaphram material meant to endure high power applications (unlike vintage driver diaphrams, like duraluminum or the phenolics as used by RCA.) " Jonathan

[Deang]

Very cool Dana. I was checking out that driver last year but never felt confident enough in my understanding of horns to pull the trigger. Basically, I just couldn't settle on a horn for it. You did good by having Mr. Wizard model out a network for it -- I'm sure it sounds fabulous.