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Old 24th June 2008, 07:42 AM   #4061
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Location: Northern Colorado
Hi Magnetar, some quick questions about Beyma.

I finally did the obvious thing and sat Karna down and asked some serious questions about WAF. She's a retired Civil Engineer, and worked for the US Army Corps of Engineers (Portland District, Columbia River) for twenty years. So she knows a thing or two about structural engineering as well as the usual WAF concerns.

Her comments - which struck me as perfectly reasonable - was the thing looked top-heavy and prone to swaying, which is no joke with 20-lb compression drivers sitting 40 inches off the floor. I had to agree. Her suggestion is a simple vertical cylinder at least 12" or more diameter, with a C-shaped cutout at the top to fit a slightly smaller C-shaped "sled" for the compression driver and horn. She also encouraged me to investigate translucent white acrylic for mounting the bass drivers, with curved side wings. Considering the big moola that cabinet-builders charge for the slightest kind of custom work, people who work with acrylic sheet for artsy interior decorators might not charge any more on a per-piece basis. Gotta look into this.

She was not thrilled with the 32" width of the side-by-side 15" dual-woofer module. I guess I could have seen that coming - it's nearly the size of a Klipschorn, after all. I mentioned the Beyma 21L50 you've had good luck with, and that size, combined with a single 12-inch wideband driver sitting above it, got the go-ahead.

All fine until I checked the price at US Speakers - whoa, US$640 each! It's one thing to pay for fancy Alnico drivers, but I guess I have problems with a big dumb subwoofer costing even more. So ... after the long wind-up, here comes the question:

What about the Beyma 18" drivers? I noticed that a single 18-incher has more volume displacement that a pair of Selenium 15PW3's. Looking at the 3rd-harmonic distortion figures, and discarding models with lowish Qts and peaks in the midrange (both undesirable), the three standouts appear to be the SM118N (at US$150), the 18G40 (at US$300), and the 118Nd/W (at US$400).

Looking very closely at the 18G40 distortion curves, it appears to have the lowest and smoothest 3nd harmonic over the working band of 50 Hz to 300 Hz, with the fewest "glitches" and odd-looking artifacts. The volume displacement is pretty good too, more than three times that of a single Selenium 15PW3.

Another quick question I'll throw out to the peanut gallery - how do the JBL 18-inchers compare to the Beyma's? Specifically, a JBL 2241H to the Beyma 18G40? The JBL 2242H costs about the same as a Beyma 21L50, so that's not as attractive unless it's teh most awesome woofer ever made.
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Old 24th June 2008, 10:47 AM   #4062
JohnL is offline JohnL  United States
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Hello Lynn,

I would say if you are shopping Beyma, you should probably check BMS as well. When I was weighing the 2x15 vs 18, BMS had some nice offerings.

I think the 18 could certainly be made to work, some of the best sound (regarding the particular traits I look for in a system) I've heard has come from my Hartley Concertmasters with those big 24" woofs. The only thing I have to remind you is big IS big. I have a huge living room (though, not a dedicated listening room) and those concertmasters are just too big, even in there. They look like a pair of dressers. Throw together some cardboard mockups of what you are planning, you might find they are even too big for your tastes.

Also, I hate to put words in someone elses mouth, but... you have a couple guys here who seem to want to bend over backwards to help you with custom driver design. I am a Lambda TD driver owner, and can happily attest to the fact that they make some of the best stuff out there. Nick and John really know what they are doing. Perhaps if you get things situated with a Beyma or BMS 18 or 21, and you decide that is the direction you want to go, a phone calll to AE with the specs you are looking for would probably net you something much better than Beyma or BMS could produce, customized to your specs, probably cheaper and I would lay a dollar against a donut saying it's going to sound better. Just because they don't currently offer an 18 or 21 doesn't mean they can't make one, it probably means they just didn't have a market for it. Having said that, these guys are businessmen, who are busy with a ton of r&d already, so I don't think I'd play that card until your design is fairly solidified.

Just my thoughts.
John
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Old 24th June 2008, 12:36 PM   #4063
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Hi Lynn,

I think your wife is very sensible. Congratulations!

If you look back a week or two when you asked for comments about your drawing I commented the baffle itself was not extended enough vertically to produce proper midbass. I said this from the experience of building many (too many) failed baffles. What works best for me is a baffle that extends up 40 inches or more in height with the bass driver at the bottom. A tall wingless baffle actually sounds better (lots!) then one with wings.

I bought the Beyma's at a local auction for cheap and since installed them in my friends basshorns. Why? We tried one in his horn and found it was far superior to his Cerwin Vega 189's (that he kept blowing- his room is 60 feet deep and he listens at Grateful Dead levels!) sooooo I found a better OB driver and his bass horns are loaded up with my Beymas-

I replaced them with the Pyle Pro PDW21250. The specs are promotional garbage (they rate them at 107 db/w ect) but the price is right. at around 320 a pair They require less EQ then the Beyma - with no eq they go to 45 cycles now, my crossover point to the sub. They also are measuring very low distortion between 40 and 120 cycles (where I use them) provided they are high passed. IMO the 21's are the ticket if you want to keep the baffle reasonable. Mine are 24 wide by 48 high with no wings- Are they better than the JBL 2241 or 2242? I never compared them on a baffle but I feel they have more surface then 18's and with the higher QTS they are more efficient on a board. I like them better then the Beyma. Only problem with the Pyle is the funky looking dustcap - my solution was a 99 cent can of flat spray paint -

I also should note - I tried to like large format drivers for years now and have finally decided they are not for me in the midrange. A good 12 (like my SRO's, yummmmm) or 10" crossed to GOOD small format driver in a good, decent, dispersion (match to mid) horn between 1200 and 1800 does everything better for me. A 12" mid can go to 120 cycles so you get any of the nasties down in the bass driver (use 4th order electronic and biamp) with not too much trouble and a much more 'complete' midrange. You also have the choice of using a smaller horn with the small format driver that can be integrated better with the mid - it can be on the same baffle! Your 288's could do the job well but will require the ribbon. To me a 'one board' approach is a more elegant, practical solution.





Quote:
Originally posted by Lynn Olson
Hi Magnetar, some quick questions about Beyma.

I finally did the obvious thing and sat Karna down and asked some serious questions about WAF. She's a retired Civil Engineer, and worked for the US Army Corps of Engineers (Portland District, Columbia River) for twenty years. So she knows a thing or two about structural engineering as well as the usual WAF concerns.

Her comments - which struck me as perfectly reasonable - was the thing looked top-heavy and prone to swaying, which is no joke with 20-lb compression drivers sitting 40 inches off the floor. I had to agree. Her suggestion is a simple vertical cylinder at least 12" or more diameter, with a C-shaped cutout at the top to fit a slightly smaller C-shaped "sled" for the compression driver and horn. She also encouraged me to investigate translucent white acrylic for mounting the bass drivers, with curved side wings. Considering the big moola that cabinet-builders charge for the slightest kind of custom work, people who work with acrylic sheet for artsy interior decorators might not charge any more on a per-piece basis. Gotta look into this.

She was not thrilled with the 32" width of the side-by-side 15" dual-woofer module. I guess I could have seen that coming - it's nearly the size of a Klipschorn, after all. I mentioned the Beyma 21L50 you've had good luck with, and that size, combined with a single 12-inch wideband driver sitting above it, got the go-ahead.

All fine until I checked the price at US Speakers - whoa, US$640 each! It's one thing to pay for fancy Alnico drivers, but I guess I have problems with a big dumb subwoofer costing even more. So ... after the long wind-up, here comes the question:

What about the Beyma 18" drivers? I noticed that a single 18-incher has more volume displacement that a pair of Selenium 15PW3's. Looking at the 3rd-harmonic distortion figures, and discarding models with lowish Qts and peaks in the midrange (both undesirable), the three standouts appear to be the SM118N (at US$150), the 18G40 (at US$300), and the 118Nd/W (at US$400).

Looking very closely at the 18G40 distortion curves, it appears to have the lowest and smoothest 3nd harmonic over the working band of 50 Hz to 300 Hz, with the fewest "glitches" and odd-looking artifacts. The volume displacement is pretty good too, more than three times that of a single Selenium 15PW3.

Another quick question I'll throw out to the peanut gallery - how do the JBL 18-inchers compare to the Beyma's? Specifically, a JBL 2241H to the Beyma 18G40? The JBL 2242H costs about the same as a Beyma 21L50, so that's not as attractive unless it's teh most awesome woofer ever made.

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Old 24th June 2008, 04:35 PM   #4064
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Lynn have you considered the Ciare 18.00NdW1 ? As much or more than swept volume as the Beyma's, very low inductance motors, and the price is right. I've heard very good things about this model range of Ciares. Qts is slightly lower than the Beymas though.
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Old 24th June 2008, 04:43 PM   #4065
Variac is offline Variac  United States
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I think it depends on what you were planning to make the cylinder out of. You can get 6" diameter aluminum tube for a reasonable price, but not cheap, probably at leat $300 for the materials. It comes in square shapes too, which are lots easier to attach brackets, etc to.

Pyle Pros 21" for $150 ea. :

http://www.audioblowouts.com/Other_W...APDW21250.html

They look pretty well built.. A big dumb strong woofer- I like it!



US speaker has an 18 Sound 21" for $500 - that's a bit cheaper then Beyma
Response curve not terribly inspiring
9,5mm xMax
99dB efficient
QTS.235
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Old 24th June 2008, 04:47 PM   #4066
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A peek at the back of my compact three way

Click the image to open in full size.
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Old 24th June 2008, 06:46 PM   #4067
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Quote:
Originally posted by Magnetar
A peek at the back of my compact three way
Is this the Beyma 21'' + SRO 12'' modded field coil + Emilar CD in RH horn you posted here ?

"Impersive"....Not least considering your previous monsters (and that they sure must be "low compromise" in comparison)
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Old 24th June 2008, 08:05 PM   #4068
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Quote:
Originally posted by FlorianO


Is this the Beyma 21'' + SRO 12'' modded field coil + Emilar CD in RH horn you posted here ?

"Impersive"....Not least considering your previous monsters (and that they sure must be "low compromise" in comparison)

Hello, I changed the woofers out to the Pyle 21" but yes this is the speaker I was referring to.

The sound is like heaven.- especially with LP's..

Cheers
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Old 24th June 2008, 08:08 PM   #4069
pdan is offline pdan  Europe
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Building a loudspeaker system is easy, providing you live alone and only keep the company of cats and cockroaches. Then you can do what you want, you can even imagine yourself to be a cross between Durand Durand and Furtwangler. Unfortunately, it's not given to many to be one of these happy curios and know the enjoyments of Wagnerian Delusions.

For most the building of loudspeaker is a subtle and delicate art ... we want it to please the eye as well as the ear, but It's easy to loose sight of the original intention, the project then runs into unnecessary problems. Sometimes we need to step back, pause, re- ***** and ask ourselves whether or not we are being true to our original intention and what is most important. As a student painter, this a lesson I'm constantly learning and re-learning.

The one constant for most of this project has been the RAALs, so I assume that these have become the most important aspect of this project. But do they create more problems ( visually and sonically ) than they solve ?


Cilla
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Old 24th June 2008, 08:14 PM   #4070
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Quote:
Originally posted by Magnetar
Hello, I changed the woofers out to the Pyle 21" but yes this is the speaker I was referring to.

The sound is like heaven.- especially with LP's..
Nice to read that... To bad the Electro Voice (maybe also the Emilar ?) are unobtainum -- at least for those "on the other side of the pond"

A similar concept -- but with "COTS" drivers -- e.g. the Beyma / BMS / Pyle + (upcoming ?) 12V field coil, OB version of TD12M / TD10M + CD-WG.... now that 3-way would be a concept within the reach -- and usability !! -- of many (myself included)

Congrats again,

Florian
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