Erin's Audio Corner reviews the Philharmonic Audio BMR Monitor V2 (May 30th)

[Dennis Murphy]

Will be interesting to see the options for higher power handlings ribbons. It seems major manufacturers that use ribbons fabricate their own (Elac, Dali), while some smaller companies have them built to spec (Concident), where it may not be obvious who their builder is. Then there are the common ones available for custom builds like the Dayton, Fostex, and HiVi, plus the RAAL and apparently a few others. Apparently if you spend enough $ Raal has models that can handle higher power levels?

Here's where we have to be careful about applying the term "ribbon" to AMT drivers, which operate differently and almost never provide the wide horizontal dispersion of a true ribbon like the RAAL. I've worked with a wide variety of AMT's and haven't found one that has any advantage over a good dome, and most have fairly narrow dispersion. RAAL does make a very long ribbon that might have substantially greater power handling than the smaller models, but the vertical dispersion is so restricted that you're locked into a precise sitting position, and they cost around $900 a piece. The best dome I've found is the Transducer Lab ceramic, which measures perfectly and sounds very similar to the RAAL. I'm exploring whether they can be obtained in sufficient quantity for what I have in mind.

 

[cavedriver]

Yeah, I figured I would ask forgiveness for saying "ribbon" when of course there are many things out there that are not strictly a ribbon, including planar magnetics, AMT's and oddballs like Nestorovic's "leaf" tweeters. I meant to broadly refer to all the flat and folded sheet tweeters versus cone designs but of course admit that covers a wide range of performances and operating requirements. Not sure what the current industry consensus is on the use of titanium, ceramic, and more exotic material domes in tweeters and their availability for independent designs (versus in-house speakers with proprietary drivers like Focal).

 

[nerdoldnerdith]

I'm trying to wrap my head around the compression measurement. Very different than the old version.

The woofer runs out of excursion on the 102dB sweep.

A speaker like this may be able to play low, but not with the kind of authority you get from a full-range tower. That is why most bookshelves are tuned higher.

 

[Kachda]

Just posted my pair for sale actually:

FS: Philharmonic BMR v2 rosewood rectangular (pair)

A like new pair of BMR, tried them out for awhile but going back to narrower directivity. These are rectangular with the rosewood finish, and are in perfect working condition. All surfaces look beautiful as well. Price is $1600 + free shipping to the continental USA. I am located in the San...

www.audiosciencereview.com

Have they been mounted upside down in your pictures?

 

[mj30250]

Yes, that's upside down. It can be done when necessary to get the tweeter on-axis with ear height, as RAAL ribbons are more limited in vertical dispersion than domes.

 

[BrokenEnglishGuy]

Here's where we have to be careful about applying the term "ribbon" to AMT drivers, which operate differently and almost never provide the wide horizontal dispersion of a true ribbon like the RAAL. I've worked with a wide variety of AMT's and haven't found one that has any advantage over a good dome, and most have fairly narrow dispersion. RAAL does make a very long ribbon that might have substantially greater power handling than the smaller models, but the vertical dispersion is so restricted that you're locked into a precise sitting position, and they cost around $900 a piece. The best dome I've found is the Transducer Lab ceramic, which measures perfectly and sounds very similar to the RAAL. I'm exploring whether they can be obtained in sufficient quantity for what I have in mind.

Is not the Elac carina AMT? it's pretty wide and is not ribbon
Or im wrong?

 

[tw 2022]

Here's where we have to be careful about applying the term "ribbon" to AMT drivers, which operate differently and almost never provide the wide horizontal dispersion of a true ribbon like the RAAL. I've worked with a wide variety of AMT's and haven't found one that has any advantage over a good dome, and most have fairly narrow dispersion. RAAL does make a very long ribbon that might have substantially greater power handling than the smaller models, but the vertical dispersion is so restricted that you're locked into a precise sitting position, and they cost around $900 a piece. The best dome I've found is the Transducer Lab ceramic, which measures perfectly and sounds very similar to the RAAL. I'm exploring whether they can be obtained in sufficient quantity for what I have in mind.

New aa+'s??

 

[Newman]

Is not the Elac carina AMT? it's pretty wide and is not ribbon
Or im wrong?

Not to the same degree though. A RAAL might be 5 dB down at 60 degrees and 20 kHz.

 

[jhaider]

Is not the Elac carina AMT? it's pretty wide and is not ribbon

The horizontal dispersion width has much less to do with driver operating principle than simple geometry. BMR’s tinfoil strip is thin, so it has wider dispersion to higher frequencies. The same applies to, e.g, the tiny plastic doughnuts behind JBL 7-Series and SCL-3/4/5 waveguides. (Not saying Raal is otherwise as advanced as that driver, of course.)

 

[Dennis Murphy]

New aa+'s??

No--I'm talking about a dedicated high output HT tower. But I checked on the Transducer Lab availability, and it doesn't look like they're being produced anymore. Bummer--they were great tweeters. But now that you mention it, I am bringing back the AA, although not with the AA+ Morel tweeter. I'm discussing that on my AVS speaker thread.

 

[fluid]

Could You show data, because I've not seen it that way?

3kHz@60° there is just one tiny little dB, or 4kHz@60° one and a half dB of a difference.

I don't know what else to show other than a simulated piston of the same size vs a measured response. A change in directivity of 1 to 1.5dB to me is quite a lot in relative terms for drivers of this size. As stated above the greatest differences will be seen further off axis (beyond the hificompass measurement angles) and higher in frequency. If the design is striving for the widest and most even directivity these differences are why the BMR is more suitable, the 90 degree off axis angle has the greatest impact on the soundpower due to the weights given in it's calculation.

 

[fineMen]

I don't know what else to show other than a simulated piston of the same size vs a measured response. A change in directivity of 1 to 1.5dB to me is quite a lot in relative terms for drivers of this size. As stated above the greatest differences will be seen further off axis (beyond the hificompass measurement angles) and higher in frequency. If the design is striving for the widest and most even directivity these differences are why the BMR is more suitable, the 90 degree off axis angle has the greatest impact on the soundpower due to the weights given in it's calculation.

Yep, the other driver in the comparison is considerably larger, BMR=5cm, TC=9cm. Still the differences are small. The technology of "balanced mode radiator" relies on break-up. Namely a piston mode region below, and a hopefully most chaotic break-up mode beyond a certain frequency. Just the chaotic regime allows for the wider radiation on top. I cannot see how a 5cm driver would break-up as low as 4kHz. Typically the first break up occurs around 10kHz, so way beyond the BMR's operating range in this design. The dispersion feature of the BMR is not likely to be gainful.

You are right to mention the target of the wide dispersion. But as always loudspeaker design is about finding compromises. I doubt that one dB more or less would outweigh the otherwise possible reduction in intermodulation or more clarity respectively.

The Philharmonic BMR has in some respect a quite special architecture. Very wide horizontal dispersion all through, but in the treble, due to the ribbon, an unusual steep and deep narrowing. Don't know if these features are anticipated by all, or put to reasonable use.

 

[hollis]

Have they been mounted upside down in your pictures?

No mounting, just sitting on stands with rubber bumpers. Those stands are a touch too high for them, and its very important to listen at ribbon height, so I flipped them.

 

[birdog1960]

The monitors just do it...Nike like. Simultaneously objets d'art... because that's what it's about! Love em.

 

[eboleyn]

Here's where we have to be careful about applying the term "ribbon" to AMT drivers, which operate differently and almost never provide the wide horizontal dispersion of a true ribbon like the RAAL. I've worked with a wide variety of AMT's and haven't found one that has any advantage over a good dome, and most have fairly narrow dispersion. RAAL does make a very long ribbon that might have substantially greater power handling than the smaller models, but the vertical dispersion is so restricted that you're locked into a precise sitting position, and they cost around $900 a piece. The best dome I've found is the Transducer Lab ceramic, which measures perfectly and sounds very similar to the RAAL. I'm exploring whether they can be obtained in sufficient quantity for what I have in mind.

I'm definitely not a serious speaker designer like yourself, but I'd recently grabbed a set of RAAL's rarely offered very large ribbons (a 210 x 15 mm dipole, the one used one of the Ares Cerat speaker models). Agreed on the restricted vertical dispersion normally, though my plan is to experiment with some waveguides (using a CNC miller) and improve that.