Philharmonic Audio BMR Speaker Discussion

[Dennis Murphy]

Hi everyone, please accept my apologies for I'm far from being technically versed and my English skills are deficient. Yet, I felt I can have a very modest contribution, since I am the lucky owner of a pair of BMR in Salk maple finish. I have owned them for about 2 years and couldn't be happier.
I am afraid I cannot shed any light in your particular application, I am using them in an open living room of roughly 19X19ft (that is about 6.33mX6.33m) in a stereo set-up.

What I wanted to highlight was that my particular pair, which I believe was assembled by Jim Salk is very tightly matched. I am using them with Acourate room correction, but still regularly listen to them uncorrected depending on source. Once correction is applied, Acourate evaluates IACC, interaural-cross-correlation, at different time intervals. At 10 ms, I have reached about 97.0% IACC, which to the best of my knowledge, is a testament to how closely each speaker is matched to its sibling. Given that some anomalies are due to the room and may not be fully corrected by Acourate, I tend to believe it is a testament to great care in matching the speakers. What is for sure is I have not had any speakers I have personally tested that reached such a high value (amongst Sonus Faber Cremona auditor, PSB X2T, PSB B5 and a few others I may have forgotten).

Long story short, I am glad I have opted to have them built professionally. Just to make it clear, the following pic is not mine, it was taken from
http://gp-architecte.com/project/amo/

Sorry for this long post, but I wanted to share how satisfied I was with my purchase, Dennis is a true gentleman. If it weren't for audiosciencereview that pointed me towards Dr. Toole's book, I wouldn't probably have even considered those speakers. Thank you all guys!

Wow. Can I have that house if I let you keep the BMR's?
Sounds like you've been through a whole lotta speakers. You should be in good company on this site.

 

[Dennis Murphy]

I didn't realize you were using such a shallow slope on the BMR up so high, that's very interesting. Do you have any issues matching the dispersion of the 8545 and the BMR at 900hz? Or does the shallow slope take care of that?

The 8545 version used 4th order slopes crossed a little above 600 Hz. The graph is for the new SB Ceramic version. The SB woofer doesn't start to beam until well above the crossover point, so there's no problem matching dispersion in that region. I was a little concerned about keeping the match further up, but as it turned out the off axis response is about like the old version.

 

[PNWer]

When it's vertical, do you place it under your screen? If I had a projector and an acoustically transparent screen that would be ideal. If it is under your screen do you have any problem with the acoustic location being so much lower than the screen?

Thanks for the not on the cabinet. I will ask Dennis if he can send those along after I order the speakers. Probably will be a month or two before this makes the top of my list.

Our TV is wall mounted. The installation allows a vertical BMR. Slanting speaker up or just vertical make no difference when seated on the sofa.
The standard model BMR is rear ported and need space behind for maximum performance, so front port option does make a difference.

 

[DDF]

I've done a couple of 2-ways with the 8545 and was able to deal with the surround-cone resonance fairly well with a trap circuit using 4th order slopes. But my objective with the SB BMR was to achieve a nearly perfect 2nd order acoustic roll off as far out as possible in order to boost sensitivity. It's a lead pipe cinch to do that with the SB Ceramic. I've attached the reverse null simulation at 3 meters--the 2nd order slope is maintained on out to over 4000 Hz, which is far enough to produce almost perfect phase tracking and get the sensitivity up. The horizontal off axis system response is very smooth even at 80 degrees. I might have been able to do fairly well with the Scan with enough components, but the Ceramic only takes one inductor, a damping resistor, and a cap.

I used a trap as well. Nice thing about the 8545 is that the edge resonance is consistent off axis so that the trap works at all angles.

The 2nd order supresses the ceramic breakup up just enough and the low order slopes will have great dispersion. If the BMR can handle the low slopes, looks pretty good!

 

[Dennis Murphy]

I used a trap as well. Nice thing about the 8545 is that the edge resonance is consistent off axis so that the trap works at all angles.

The 2nd order supresses the ceramic breakup up just enough and the low order slopes will have great dispersion. If the BMR can handle the low slopes, looks pretty good!

The BMR driver was definitely having problems with a 600 Hz crossover. That's why I chose 900 Hz. THD stays at or below .5 % at 90 dB that way.

 

[Ilkless]

The BMR driver was definitely having problems with a 600 Hz crossover. That's why I chose 900 Hz. THD stays at or below .5 % at 90 dB that way.

Hi Dennis, do you know of any "higher-end" BMRs? The Tectonic you used is already amazing when built to a cost of $17/piece, just wondering if they are any more expensive BMRs that are built with less compromises and even higher performance. I can't seem to find measurements out there for any.

 

[Dennis Murphy]

Hi Dennis, do you know of any "higher-end" BMRs? The Tectonic you used is already amazing when built to a cost of $17/piece, just wondering if they are any more expensive BMRs that are built with less compromises and even higher performance. I can't seem to find measurements out there for any.

Excellent question and a real sore spot for me. You would think the BMR's working principles could be incorporated in a more robust version with even smoother response and lower distortion. I wrote to the company recently, haven't heard back yet. I suspect the answer is that it wouldn't fit their business model. The BMR drivers are generally used in multiples as line arrays or in special applications like airports (The Moving Walkway is Ending..........." where good intelligibility is needed at reasonable cost. Most of the BMR's have super low sensitivity. The only exception is the one I use, and I suspect it was commissioned by Cambridge Audio for use in their Aero series. I do have a design that uses four BMR's, but it's the size of Pittsburgh and costs Uber Dineros.

 

[GelbeMusik]

... it wouldn't fit their business model. The BMR drivers ... good intelligibility is needed at reasonable cost. ...I do have a design that uses four BMR's, but it's the size of Pittsburgh and costs Uber Dineros.

Ah, the BMRs are going to be sold ready made, and still as a kit / flatpack, from China, for 1,5k$ up to 2,2k$ per pair? I raised some critique. Several design decisions are still not understandable for me, which of course goes back to my lack of knowledge.

For instance the eponymous BMR. It doesn't radiate wider than the Tymphany TC9FD18-08, which costs half, has higher power handling and severely less distortion, rendering it more versatile. The discusson on ribbon versus 3/4" dome didn't change my perspective. I think it was basically about taste versus objective data.

What I'm really a bit wondering about is the small-ish woofer. I have the SB at hand myself. I've seen better drivers, when it comes to power handling. Not the least, size matters anyway.

 

[Ericglo]

Hi Dennis, do you know of any "higher-end" BMRs? The Tectonic you used is already amazing when built to a cost of $17/piece, just wondering if they are any more expensive BMRs that are built with less compromises and even higher performance. I can't seem to find measurements out there for any.

Excellent question and a real sore spot for me. You would think the BMR's working principles could be incorporated in a more robust version with even smoother response and lower distortion. I wrote to the company recently, haven't heard back yet. I suspect the answer is that it wouldn't fit their business model. The BMR drivers are generally used in multiples as line arrays or in special applications like airports (The Moving Walkway is Ending..........." where good intelligibility is needed at reasonable cost. Most of the BMR's have super low sensitivity. The only exception is the one I use, and I suspect it was commissioned by Cambridge Audio for use in their Aero series. I do have a design that uses four BMR's, but it's the size of Pittsburgh and costs Uber Dineros.

I had wondered the same question after looking at this driver. I imagined what SB could do with this tech by increasing performance while keeping the price in check. That said I am glad you inquired and it doesn't look like it would be a priority at least for Tectonic.

An Uber Dinero BMR? Would this be incorporating the ideas of your friend in Virginia?

 

[617]

It's worth nothing how profoundly different BMRs are from other drivers. The dispersion they offer is wider than a small dome tweeter. I've often wondered if you could make one with more xmax, but they really don't operate according to the rules of other drivers. I suspect the 1-3" BMR is the 'sweet spot' and if you tried making anything much bigger you wouldn't get as smooth a response.

These drivers break the rules. To me, it's the most impressive technology in audio in recent memory. The idea of embracing and controlling diaphgragm breakup by applying mass to the cone is a very novel idea, but actually creating a 12 dollar driver with this kind of response is truly amazing to me.

 

[Ericglo]

It's worth nothing how profoundly different BMRs are from other drivers. The dispersion they offer is wider than a small dome tweeter. I've often wondered if you could make one with more xmax, but they really don't operate according to the rules of other drivers. I suspect the 1-3" BMR is the 'sweet spot' and if you tried making anything much bigger you wouldn't get as smooth a response.

These drivers break the rules. To me, it's the most impressive technology in audio in recent memory. The idea of embracing and controlling diaphgragm breakup by applying mass to the cone is a very novel idea, but actually creating a 12 dollar driver with this kind of response is truly amazing to me.

I agree. When looking at the construction, I am not sure how to improve upon it.

The first time I saw the measurements from Erin's site I wondered if Rick Craig could incorporate them into a CBT.

 

[DeruDog]

Our TV is wall mounted. The installation allows a vertical BMR. Slanting speaker up or just vertical make no difference when seated on the sofa.
The standard model BMR is rear ported and need space behind for maximum performance, so front port option does make a difference.

Cool, thanks. I will be making a new custom stand for my audio equipment and TV, and will have space behind so no worries. I will actually try it both ways and see which works out the best. Basically, I can have the center almost on the floor below the TV, and the audio electronics to either side. As long as the acoustics are not distracting, this might be the perfect setup! Good to hear that a vertical speaker works for you and it is encouraging to me. Until now I was pretty much resigned to doing a custom cabinet of some sort, which might mess up the acoustics since the front baffle would be a different shape.

 

[GelbeMusik]

The dispersion they offer is wider than a small dome tweeter.

Compare yourselves:

https://hificompass.com/en/speakers/measurements/tectonic/tectonic-tebm46c20n-4b

https://www.madisoundspeakerstore.com/approx-3-fullrange/vifa-tc9fd18-08-3.5-full-range/

The latter is perfectly usable down to 350Hz--I've two handfull of them around, for ambience. These cheapies rock.

Of course the BMR are fascinating. But a wideband always was kind of a BMR. Only that the latter exploit increased stiffness, less damping and higher masses. This came handy, when the radiation pattern became more predictable due to new mathematics, computer power and new materials.

Please don't spread the advertising narrative, without at least some personal cross check.

 

[DeruDog]

A Purifi version would just be an upgrade option. I don't have any plans to continue with the Scan woofer now that the SB Ceramic is available.

Do you plan on offering the SB version and the Purifi version as kits, or only as completed speakers? I am really curious how those versions will turn out for you, and am interested in upgrade options.

 

[Dennis Murphy]

An Uber Dinero BMR? Would this be incorporating the ideas of your friend in Virginia?

That be the one.

 

[Dennis Murphy]

Compare yourselves:

https://hificompass.com/en/speakers/measurements/tectonic/tectonic-tebm46c20n-4b

https://www.madisoundspeakerstore.com/approx-3-fullrange/vifa-tc9fd18-08-3.5-full-range/

Please don't spread the advertising narrative, without at least some personal cross check.

You might wish to personally cross check the sensitivities on these two drivers. 84.4 dB is more appropriate for use in multiples, not as a single midrange. I've tried a whole lot of small mids, including Scan Speak and Accuton, and the BMR is the one that worked best for me.

 

[Dennis Murphy]

Do you plan on offering the SB version and the Purifi version as kits, or only as completed speakers? I am really curious how those versions will turn out for you, and am interested in upgrade options.

The present plan is for the SB version to be sold as finished speaker and the Purifi version as a kit, at least at the beginning. If the Purifi proved very popular, I might be able to commission completed speakers from Bennic. But given the probable price, I kind of doubt that's going to happen.

 

[GelbeMusik]

You might wish to personally cross check the sensitivities on these two drivers.

I replied to the claim, that BMR drivers would be as good as a small dome regarding wide disperson. I asked for a cross check. Result?

The present plan is for the SB version to be sold as finished speaker and the Purifi version as a kit, at least at the beginning. If the Purifi proved very popular, ... given the probable price, I kind of doubt that's going to happen.

For end-customers the Purify is about 450Euro, the SB about 75Euro, in Europe. In order to exploit the (claimed) excursion of the purify, one might want to redesign the reflex port because of chuffing. With only 375+ on an already substantial price of 1k+ the Purify option is going to make it.

 

[Dennis Murphy]

I replied to the claim, that BMR drivers would be as good as a small dome regarding wide disperson. I asked for a cross check. Result?



For end-customers the Purify is about 450Euro, the SB about 75Euro, in Europe. In order to exploit the (claimed) excursion of the purify, one might want to redesign the reflex port because of chuffing. With only 375+ on an already substantial price of 1k+ the Purify option is going to make it.

Obviously I would need to redesign the bass loading. Using the factory specs, you're quite right that this could prove problematic. I'll measure the TS parameters to see how close they are to the factory's, and see what can be done. Fortunately, the person I use to perform that work is highly skilled, and if anyone can figure out a way to make it work, be it with a port, transmission line, or passive radiator, I'm sure he can. If not, I have at least one other use for the Purifi's in mind.

You were clearly promoting the Tymphany TC9FD18-08 as a step up from the BMR, and I was pointing out that you might wish to do some cross checking on sensitivity. Also, can you point me to documentation for your claim that the little Tymphany has "drastically less distortion"?

 

[Zvu]

Regarding dispersion BMR wins, also on power handling/compression (32mm voice coil in BMR vs 20mm in TC9). Given that crossover frequency went up tp 900Hz, it may not be an issue, but pairing tc9 with RAAL 64-10 at 3.5kHz-4kHz might.