Help me pick a coaxial speaker ++

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A couple of years, I had started on this project, bought a bunch of drivers... but it got put on hold... This time its for real... I am helping a friend set up his studio. Walls are being demolished as I type this, and the new walls will be completed to my specs in about a month. He has given me a free hand with the design of the studio and the monitoring system. The tentative layout of the studio is attached herewith. The space currently allocated for the flush mounted speakers is 20" width, 16" depth and height is to be decided, depending on which way the design heads.

I already have a pair of NOS Exodus Audio Tempest X15s to handle duties below 100 Hz. I will definitely use a 2x6 loudspeaker management system... the DEQX HDP Express II, if we can afford it... if not, we will resort to some Behringer DCX2496 type device, until finances permit us to upgrade to the DEQX.

Now, I want a 12"+ coaxial speaker to complete the driver complement. I want it to be coaxial for two reasons : 1. The engineer will be seated relatively close to the speakers, so the path length differences between sounds coming from the mid-woofer and HF driver can become a serious issue, if they are not dual concentric... and 2. I used to work with Tannoy DMT15s and I have never enjoyed working on any speaker more... just my personal experience/opinion.

The other requirement is that it should be able play loud... at least 110 dB continuously, with peaks of 120 dB+ (@ 1m)

The amps will most probably be QSC GX7 for the subs and its smaller siblings for the mid-woofer and HF driver.

So... help me pick a coaxial driver to take me forward with this design. Specifically, I would like a sealed enclosure for the mid-bass unit, which goes down to 100 Hz comfortably - and can produce the SPL I want, in the form factor I mentioned.

Top on my list at this time is the Beyma 12CX30, just because I happen to know that it is being used in a pretty high end OB speaker... I am also interested in the Radian 512/2B...

Thank you for any inputs, caveats, warnings etc...

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Audio recording and mix studio. The front wall will be hard - extending the baffle of the flush mounted speaker. The floor will be hard. Every other surface will be as completely absorbent as I can make it, with the usage of metal and membrane trapping and insulation. This is inspired by the Non Environment approach propagated by Tom Hidley / Philip Newell.
 
Since you liked the Tannoys so much why not stick with them?

Like 12DMT or 15DMTs, would have to be second hand these days but they are completely serviceable via Lockwood Audio and others.

As for an eventual digital speaker management system (crossover to you and me) check out XTA.
Amp-wise I can wholeheartedly recommend MC2 Audio aka Quested Audio.
Quested also do speaker management which are re-badged XTA units.
 
picowallspeaker, that Ciare does look good. Low Fs, high Qts, and possibly more uniform dispersion between the mid-woofer and the HF driver, thanks to the 10" mid-woofer, which is smaller than the models I had in mind... It is now on my list of considerations, thank you.

Since you liked the Tannoys so much why not stick with them?

Like 12DMT or 15DMTs, would have to be second hand these days but they are completely serviceable via Lockwood Audio and others.

Thanks Charles... I am in India, and this is a scary thought... third world as we are, I was surprised to see that most companies I see in usspeaker.com are represented in India... Replacement, servicing etc., are accessible. I simply cannot trust our local freelance technicians to take on something like this...

As for an eventual digital speaker management system (crossover to you and me) check out XTA.
Amp-wise I can wholeheartedly recommend MC2 Audio aka Quested Audio.
Quested also do speaker management which are re-badged XTA units.

Cost is a factor. XTA/Quested is going to be way more $ than Behringer, if that is the space I'm playing in. If I'm going to invest more, I want a smart guy in the house, as I'm not very bright myself... I imagine that the DEQX is that guy...
 
Fwiw, At the time I did the comparative measurements of the available driver choices, the B&C 8CX21 had the smallest acoustic / horn discontinuity between the cone and compression driver portion.

It ended up being used in a number of our products and the front to back spacing allowed a Synergy style crossover (which doesn’t have the traditional “all-pass” phase shift and step in Group delay) so that the cone and hf can occupy the same location in time.
Most coax drivers do not sum into one source even though they appear to be just that visually
Best,
Tom Danley
Danley Sound Labs
 
RockLeeEV - thank you - that BMS does look interesting... but it has a QTS of .18 - will it work in a sealed enclosure? Any pointers to builds using this driver...

Mr. Danley - honoured to have you on board. Everyone says that a smaller mid-woofer - 5" - 8" has the best mid-range clarity and dispersion - and integrates better with the HF driver. I have no doubt that this is true. I'm coming from a different place, and I hope my explanation makes sense.

I am a sound engineer... I record and mix music for a living. Like many engineers of my generation, I am self taught, and can easily be confounded by technology. Anyway - every time I take a track I have done a stereo mix on to a film mix stage, I hear things in the low end, that I never heard in my studio. I imagined that it was the acoustics in my small room that was leading to muddiness and lack of clarity in the bass. Over the years, I have had several sets of standard studio nearfields with competent subwoofers, and the low end has consistently been a problem. Last year, I built a pair of Econowaves (RIP Zilch) with 12" Dayton woofers, in huge 170L cabinets - and whoa! there it was, the missing clarity in the bass! I was hearing the low end like I was hearing it in the film mix stages... So I have concluded that for me to hear 100 Hz - 400 Hz the way I want to, I need it to come from a large driver in a large box. A three way, with crossover points @ around 400 Hz and 3 Khz, with a 5" midrange would appear to make sense, but then again, in this room, the listener is too close to the speaker for this to be an optimal choice...

In this case, there will be a pair of nearfield monitors, on which, in fact, most of the mixing will happen. The big monitors will come on when the engineer is checking the low end, or blasting it, to impress a client.

Most coax drivers do not sum into one source even though they appear to be just that visually

This is exactly the kind of thing that destroys my innocence. Knowing that I don't know enough, but not knowing what I don't know :)
 
RockLeeEV - thank you - that BMS does look interesting... but it has a QTS of .18 - will it work in a sealed enclosure? Any pointers to builds using this driver...

If you won't be using a woofer, you will want to actively EQ it flat to ~100hz as the F3 is only 200-240hz in a sealed box. No real problem with this though. QTS would only be a limiting factor if the driver's xmax or thermal management couldn't handle an octave of linkwitz transform. or you were using passive crossovers. You could probably step up to the 15 inch BMS, but I don't know how low the BMS tweeter will play.

THe only build I know of that uses this coax - and it may be the 12C262 actually - is the Soundfield Audio 1812
 
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Audiothings

If you are on low budget why not consider Eminence Beta 12CX coaxials. You have some model calculations for enclosures on Eminence site. BMS and B&C are much more expensive.

Hi, as far as I know the Eminence drivers do not include a compression driver, these must be purchased separately. Is this correct? Because in that case, the Eminence Beta 8CX, which costs 80€ here, still needs an additional 60€ or more compression driver, which puts it very close to the price of the 161€ B&C 8CX21. Local prices may of course vary.

The B&C 8CX21 by my simulation will do an xmax limited 120dB down to 80Hz flat in a 12 liter vented box - this is very impressive for about 220€ in drivers and crossover.

Too small for OP with his 12"+ requirement, but a good driver nonetheless, even more so with Tom Danley's seal of approval.

Edit: 110dB @ 100Hz in a sealed box, xmax limited.
 
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Thanks everybody for the inputs.

May I request the educated and experienced to take a look at the Radian 512/2B please. It has some of the things I am looking for - high Qts, low Fs, apparently smooth FR (who knows what is happening off axis :) )

Couple of things are scary... they keep saying that it is a "ceiling speaker"... I don't know wtf this translates to, other than that it should work well in an infinite baffle installation, which is what we have on the cards. Usspeaker says tha the recommended crossover is @ 1.25 Khz while Radian's page recommends 1.5 KHz... I definitely want to crossover as low as I can... I am going to mail Radian, but I'm not sure what exactly I should be asking them... Any assistance is welcome...

Also, the horn loading results in a 90 degree "conical" dispersion... Did the Tannoy DMT15 have a conical dispersion characteristic? I remember somebody saying that it was "axisymmetric". God help me or strike me down. This is geting too confusing...
 
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Note that in the "High End OB speaker" you refer to, extensive work has been done to get the response to sum flat at listening position and even then it is a little scary. High fidelity systems may not be the best base template for studio monitoring systems.

The 12" Beyma also has a very low Qts and some low end problems (I'm unsure to the exact nature of the problem, so treat it as heresy) which prevents its use on OBs - hence its availability only in the version with dedicated woofers. I suspect you may have issues in small sealed cabinets as well. My designs with the 15" versions of the same speakers pointed to a largish sealed box, with bass helpers running all the way to 100 -120Hz.

There are some major problems with coaxial speakers pointed out in the thread linked in the post and crossovers are an issue. However, for ultra-nearfield listening they are still a great option. A DEQx system would be a wise investment so you can take a lot of the guesswork out of the setup. I would prioritise the purchase of the front end before you get the actual drivers in place.

I would go for either the 12XA or 12CXA from the Beyma range, with the caveat that with the use case you have presented you will have to cross really low ~800Hz. Though the compression driver can handle it, power handling will suffer quite a bit (assume 50% of the rated 90W/1KHz power) though even that should be enough output for a 17x10 heavily treated room.

The 12XA cost around 50k a pair (CXA probably more), the Eminence with a good compression driver will cost half that. IME for translating mixes and overall performance, you will be equally able to work with either, as the Beyma has an edge mostly in power handling and bass distortion, and it doesn't look to me that either of those are going to be significant issues in your application.
 
Thank you Sangram.

The Eminence is looking interesting! Their pricing is very friendly... Can I screw in a BMS 4550 to the Eminence Driver? This CD can be crossed over as low as 800 Hz... I notice that the 4550 has nothing that can screw on to the Eminence... is there some standard adaptor for this kind of thing...?

I am little wary of the Beyma 12XA because of the 2" diaphragm... I am told that HF response suffers as the diaphragm size gets bigger...

Still hoping somebody will chime in on the Radian... from where I'm looking, it seems to be the optimal driver for my requirement...
 
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Eminence PSD 2002S ("S" being "screw" version of PSD 2002) can be screwed directly to Beta 12 CX (and Beta 15CX). May be that it is possible to use Eminence APT3 adapter to screw other comp. drivers to Beta.

You will not have significant loss of HF with big diaphragms as frequency response of compression drivers depend mostly on diameter of throat (not diaphragm).
 
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