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BEYMA 12XA30ND 12" Coaxial Driver Impressions

milezone

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I recently assembled a pair of speakers using Beyma 12XA30ND coaxial drivers (12"woofer mounted around a 2" throat compression driver) in a simple open baffle configuration. I've heard and owned many varieties of well regarded and exotic speakers over the years including Genelec Ones, electrostatic speakers (Quad 57s, KLH 9s, Acoustat 3s with servo amplifiers, King Sound, Soundlabs), JBL horns, Meyer Sound BlueHorns, full range drivers with ribbon tweeters, Apogee Studio Grand panel ribbons, Kharma Enigma, Wilsons, Magicos, Linkwitz LX521.4, plasma tweeters, vintage Tannoy silvers among others.

Many of these designs have major shortcomings -- panels are fussy, fragile, have poor dispersion and often present an unnatural sound due to large driver size, horns tend to have colorations which are oftentimes unbearable, many of these designs are excessively expensive, and some scarcely available to do failing parts and obsolescence.

I'm powering the Beymas with an inexpensive single ended 4w+4w tube amplifier -- https://www.ebay.com/itm/251524489767. According to the vendor this amp has low distortion specs for a single ended amplifier. I don't have measurement equipment so who knows... The combination with the high efficiency drivers and a Topping D90S sounds excellent. I'm using the recommended Beyma FD2XA crossover. In small open baffles the treble was a bit accentuated at first. There's an aluminum bridge pin on each crossover which can be removed to reduce the treble by 1.5db. This tamed the treble to a degree that is satisfactory. I believe that with more wattage (10W+ tube or 100W+ SS amplification) the frequency response would be more even. I intend to compare some higher watt solid state amplifiers with the inexpensive FU19 tube amp that I'm using now. And in addition bi amp the drivers in order to experiment with digital filters and make measurements. In addition I think a 15" complementary driver to handle the bass would improve these speakers further. All that said I'm drawn to the simplicity of the setup as it is right now compared with speakers which go the route of complexity (Genelec Ones, Kii 3s, Danley Synergy Horns, etc.).

I own two pairs of Genelec 8331As and have demoed a pair of 8351Bs in the same listening room as the Beymas. The primary difference when comparing the two speakers is the Genelecs seem constrained or limited in dynamics compared to the Beyma coaxials. And the Beymas have a more open and effortless presentation. I attribute this to the high efficiency drivers and possibly also the lack of DSP. Contrary to what I imagined would be the case, I prefer the treble detail of the Beyma drivers. They are more resolving than my Genelecs. These are outstanding drivers that are seldom matched at any price point. As anticipated the sound signature of these speakers is extremely dry and fast and they emit a sound that is dynamic and tactile.

Edit: Upon comparison with my other speakers, there is no perceived difference in dynamics between these Beymas and my Genelecs at normal listening levels. As mentioned the Beymas perform better at loud volumes which my 8331s can't reach without clipping severely. And I maintain that I prefer their performance to the Genelec 8351s which I demoed. My conclusion at this point, is that dynamics and driver technology and or sensitivity are not necessarily related. The Beymas are excellent for filling a large space as they can play loud without any reduction in resolution, and presumably have good directivity at mid to far field listening distances. My conclusion is that for any normal size home, a large coax like this one is sufficient. Horns are presumably necessary in larger venues, and or to achieve certain directivity characteristics, or if one desires to use a specific variety of compression driver for whatever reason.
 
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More Dynamics Please

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Interesting combination. No question that well-designed open baffle speakers can produce a captivating sound. What are your baffle dimensions and how did you arrive at them? The 1.8 kHz or higher crossover recommendation does see a bit high from a 12" woofer to a large compression driver considering that there are compression drivers available that can be crossed over at <1 kHz, which would seem more appropriate for best results with a 12" woofer.
 
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milezone

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The baffles are 24" x 20" I have them mounted in a 19" rack for testing purposes at this point. This size was arrived at because that's the size of the rack that I'm using. No other reason. Probably not optimal though they sound phenomenal. I have experienced open baffle speakers -- Pure Audio Project -- and like the sound signature. I would describe the sound as less resonant a boomy than many traditional ported enclosures. And also a room coupling effect is achieved similar to electrostatic speakers. I suspect that to a degree, an increase in phase cancellation in an open baffle design, makes up for increases is room interactions and reflection as the sound is clean and precise.

I agree I intend to experiment with lower crossovers as that's part of the advantage of these types of compression drivers.
 
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More Dynamics Please

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DVDdoug

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In addition I think a 15" complementary driver to handle the bass would improve these speakers further.
In a proper enclosure (not open baffle) it should help a lot!

when comparing the two speakers is the Genelecs seem constrained or limited in dynamics compared to the Beyma coaxials
I'm not sure what you are perceiving as "dynamics". Speakers are linear (unless over-driven). That means a 3dB increase in electrical signal results in 3dB increase in acoustic loudness.

If you are over-driving the tube amp it might be clipping, maybe it's soft-clipping (which is a tendency of tubes). Clipping (or limiting) is a kind of dynamic compression (a reduction of dynamics).
 
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milezone

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Yes the 15" would be in a large closed back front ported enclosure.

I think the larger drivers pushing more air 12" and whatever the compression driver diaphragm size is:

https://en.toutlehautparleur.com/un...p755nd-and-hf-section-in-12xa30nd-16-ohm.html

vs 5" and 1" in the 8351B is what contributes to the observed difference. Just as a headphone at 3' isn't going to sound dynamic or accurate compared with a proper loudspeaker.

As for clipping, the Genelec One series don't play that loud relative to other similarly priced studio monitors. The resultant compressed sound when an opamp or whatever ss component in the circuit is clipping contributes to the "limited" sonic nature when compared with the Beymas. For near field the Genelecs are the best option out there to my knowledge. At a range of ~10' or greater another setup like these Beymas would be a better option.
 

abdo123

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I really think coaxials are the future of hi-fi, they try to achieve what Tom Danley's Synergy horn does but in a more sensible price.
 
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milezone

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I really think coaxials are the future of hi-fi, they try to achieve what Tom Danley's Synergy horn does but in a more sensible price.

They've been the future when Western Electric, Tannoy and Altec introduced them over 80 years ago. I prefer a two driver two way design from a simplicity stand point compared to a synergy horn which is design and material excess in my opinion and potentially introduces unnecessary variables. That said perhaps in an arena far field environment a synergy horn is an excellent solution.

Edit: I am curious to hear a pair of Synergy horns after hearing these Beymas. I recall some saying they could be more resolving -- possibly fixed with a superior compression driver? In addition I plan to experiment with compression drivers in the coming months.
 
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q3cpma

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As for clipping, the Genelec One series don't play that loud relative to other similarly priced studio monitors. The resultant compressed sound when an opamp or whatever ss component in the circuit is clipping contributes to the "limited" sonic nature when compared with the Beymas. For near field the Genelecs are the best option out there to my knowledge. At a range of ~10' or greater another setup like these Beymas would be a better option.
8361-MAX.png

115~120 dB at 3% THD in the midrange and 105-110 dB in the LF area higher than 80 Hz. Add 3 dB for a decent boundary gain and 6 dB for pair gain and I wonder where you're lacking SPL.
Sure, you'll never reach PA levels with midfield studio monitors, gotta use the main monitors for that (i.e. 1237/8A, with potent compression drivers, exceptional in-house midrange and decent horn loading for both), but the 8351B/8361A coaxial assembly plays almost as loudly as the mighty Neumann KH420A, which is described as a main monitor by Neumann.
 

q3cpma

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They've been the future when Western Electric, Tannoy and Altec introduced them over 80 years ago. I prefer a two driver two way design from a simplicity stand point compared to a synergy horn which is design and material excess in my opinion and potentially introduces unnecessary variables. That said perhaps in an arena far field environment a synergy horn is an excellent solution.
Balancing IMD and dispersion matching is basically impossible for two way coaxials, though. Either the woofer is too big and you get a wonky directivity, or it's too small and the excursion becomes too big.
 

voodooless

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Interesting project! What made you choose the Beyma over other 12” coaxes, like from BMS or Faital Pro?
 

thewas

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Sure, you'll never reach PA levels with midfield studio monitors, gotta use the main monitors for that (i.e. 1237/8A, with potent compression drivers, exceptional in-house midrange and decent horn loading for both), but the 8351B/8361A coaxial assembly plays almost as loudly as the mighty Neumann KH420A, which is described as a main monitor by Neumann.
Nope, the KH420 is described and sold as a midfield monitor by Neumann:

Three Way Midfield Monitor

KH 420 G
Powerful tri-amplified midfield studio monitor – high-precision dispersion with tremendous sound level reserves.

.....

THE GOLD STANDARD IN THE MIDFIELD RANGE
The KH 420 is designed for a working distance of 1.5 to 3 m (5’ to 9’).

Source: https://en-de.neumann.com/kh-420
 
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milezone

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115~120 dB at 3% THD in the midrange and 105-110 dB in the LF area higher than 80 Hz. Add 3 dB for a decent boundary gain and 6 dB for pair gain and I wonder where you're lacking SPL.

I believe I'm responding more to the 8331 which I own and don't play loud. The 8351's did get plenty loud. Even still I was able to get them to clip as observed by the power lights flickering red at fairly moderate volume levels for a "mains" monitor. At these volumes there was a very noticeable "woof" from the rear ports of the Genelecs (and maybe also the front ports). A non issue with these open baffle speakers. Resonances and anomalies of this nature are nowhere to be found.

These Beyma drivers get louder and are cleaner (with less perceptible distortion and or resonances) at that volume driven by the stereo 4 watt tube amp that I'm using currently than the 8351s which I demoed in the same room.

Balancing IMD and dispersion matching is basically impossible for two way coaxials, though. Either the woofer is too big and you get a wonky directivity, or it's too small and the excursion becomes too big.

I'm not at a level of knowledge at this point to phase match and dispersion match drivers. I like to believe that these Beymas fall within the realm of what's deemed tolerable relative to the majority of the market as these speakers sound excellent to my ears. I can't say with 100% certainty I prefer them to the 8351s as I have the Beymas in a more optimal position in the room compared to the 8351s which does make a huge difference. I prefer the presentation of these to the 8351s and they sound as or more detailed. I'm very impressed with the quality of these drivers. Frankly they sound ridiculously good.

Interesting project! What made you choose the Beyma over other 12” coaxes, like from BMS or Faital Pro?

Beyma seems to have a deeper product line across their range compared with BMS and Faital. Faital just released a 12" coax with a 1.4" throat. I was drawn to the 2" throat of the compression driver on the Beyma drivers and the seemingly very high quality diaphragm. According to the plots on USSpeaker where I purchased them, the Beymas measured best as far as I recall.
 
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dfuller

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8351B/8361A coaxial assembly plays almost as loudly as the mighty Neumann KH420A, which is described as a main monitor by Neumann.
Speaking from experience with KH310s only, they get monstrously loud without falling apart. Like too loud to tolerate. I can't imagine how loud the KH420s are, but I want a pair.


Anyway...
These Beyma drivers get louder and are cleaner (with less perceptible distortion and or resonances) at that volume driven by the stereo 4 watt tube amp that I'm using currently than the 8351s which I demoed in the same room.
It seems likely that it's higher sensitivity to me, if a flea watt amp like that can drive them crazy loud. Which does make sense, given the big woofer combined with a compression driver/horn.

EDIT: I looked up the datasheet. Sensitivity is bananas high - 98dB for the LF, and 105dB for the HF compression driver. wow!!!
 
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milezone

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Yes they are very sensitive. In addition they are very composed at high levels driven by the 4W amplifier with no evidence of strain or distortion.
 

voodooless

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Beyma seems to have a deeper product line across their range compared with BMS and Faital.

But you just need one model ;). More choice does not mean better choices (nor worse for that matter).

Faital just released a 12" coax with a 1.4" throat. I was drawn to the 2" throat of the compression driver on the Beyma drivers and the seemingly very high quality diaphragm.

But why is 2” an advantage? Specially with the high crossover point? It also has more HF beaming.

According to the plots on USSpeaker where I purchased them, the Beymas measured best as far as I recall.

You mean this one?
1625551146982.gif

It has a 100dB scale! The deviation in FR is still more than about 13 dB. That is hardly Genelec territory.

Now, none of this makes it a bad speaker, but I think these could definitely benefit from a lower X-over point and some EQ. The directivity mismatch can be seen clearly here around 2 kHz:
1625551769615.gif
 
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milezone

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I've intended to add a bass driver from the get go and preferred Beyma's 15" offerings to other brands.

The 2" compression driver seemed the most "overbuilt" at the time of purchase which in part inspired my curiosity to build this speaker; wondering how a compression driver coaxial PA/studio monitor driver would fare against less overbuilt hifi speakers. The difference in sound quality is substantial in my opinion. They are on the level of the Genelecs and also equal to or better than older Tannoy coaxial speakers which I'm fond of. At low volumes the Ones are on par and maybe superior -- certainly more precise in their directivity and fr. At high volumes the Beymas behave better which I attribute in part to the open baffle configuration. As has been stated before, Genelecs Ones with subs may resolve the issues I observed.

The Beyma's don't measure well and according to the person posting here: http://www.hifi-forum.de/viewthread-104-27294.html they measure even more poorly than your (voodooless) plots suggest. There is a substantial dip in the upper frequencies perhaps due to beaming. Maybe a 1.4" throat compression driver would have been a better choice though I like what I've got going so far. The person posting on the German forum EQ'd the Beyma's extensively and I intend to do the same.
 
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voodooless

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I’m guessing there might be quite some sample variation due to how high the voice coil is glued to the cone. That is quite a common issues with coaxes. They guy on the German forum has quite some inventive solutions.

This is kind of why I like the new BMS coaxes: they don’t have a dust cap, so they must take care to have a good transition from CD throat to cone.

Also interested in the latest breed of Faital Pro’s
 

Geert

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They are on the level of the Genelecs...

The Beyma's don't measure well and according to the person posting here: http://www.hifi-forum.de/viewthread-104-27294.html they measure even more poorly than your (voodooless) plots suggest. There is a substantial dip in the upper frequencies perhaps due to beaming. Maybe a 1.4" throat compression driver would have been a better choice though I like what I've got going so far. The person posting on the German forum EQ'd the Beyma's extensively and I intend to do the same.
The Beymas don't measure well, the crossover frequency is still to high, you didn't EQ them yet, they're in an improvised open baffle so probably missing some low end, and you already rate them higher than Genelec studio monitors? And personally I have never heard a 2" compression driver sound realy nice (refined).

I can imagine these speakers have certain positive qualities, I'm a coaxial fan myself, but can it be you're a bit over enthusiastic?
 
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milezone

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Edit: The speakers are lacking in bass compared to even my 8331s. They sound very detailed and there's minimal if any perceived treble harshness. I find Genelecs to be very lively and exciting compared with other studio monitor brands which is why I prefer them. These Beymas possess that quality to an even greater degree. In addition to that quality, what I like about them is their composure at high listening levels. I believe that speakers measuring well is an important first step to producing a quality speaker and am not suggesting otherwise. I think these speakers have a lot of potential and I'm content with them as is though I intend to put in some effort to improve them further.

While it may seem ignorant I never really understood the value of mains monitors in comparison to something like an 8331. After having these set up for two days I can say with certainty there is an obvious advantage to bigger speakers and drivers as listening levels increase.

I don't intend to explore speakers in the bookshelf realm as I'm set up with the 8331s. Going forward I intend to devote my explorations to improving these coaxials, experimenting with compression drivers a two way small horn configuration, and maybe revisiting a two way electrostatic build implementing a small panel and a Linkwitz 521 style bass section. Frankly these drivers feel a bit dated when comparing to something like the Genelec Ones or considering electrostatic technology and the materials available today. That said they sound excellent to my ears and have lots of potential. I would like to see Genelec update their main monitor line with something as contemporary as the One series. Having heard these coaxials in comparison with my 8331s, speakers like the Genelec 1238A and the ATC SCM150 are very appealing.
 
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