Philharmonic BMR Speaker Review

[MZKM]

The curved sidewalls are inacceptable, design-wise.

Lots of costly speakers used curved sidewalls, it helps with performance. To have the same performance with a traditional box cabinet would likely mean thicker panels and more robust bracing.

Besides just internal performance, I wonder how the curved panels affect the frequency response, as it slightly adds to what beveled/rounded baffle edges accomplish.

 

[Sonny1]

(The link to the flat-pack leads back to Your home page.)

The ribbon, sealed or not dictates a higher x/o frequency, but still it distorts considerably. We have uneven directivity in the vertical, the possible mechanical vulnerability, the high price. For not more than a tiny bit of wider dispersion in the tops of the hights.

The BMR again dictates a higher x/o due to otherwise too high of distortion figures. Even bigger problems in respect to vertical directivity.

The woofer is expensive, especially when compared to more contemporary offers. With a more competent mid the x/o would be more relaxed, the woofer could have been way cheeper. Alltogether with less intermodulation, where the woofer is always the main contributor.

So, it seems funny, but the measurements don't look that bad. Two things appear less fortunate to my eye.

- The curved sidewalls are inacceptable, design-wise.

- The distortion, whether perceptible or not, must not be. One might argue, that these aren't that bad, because of and so forth, o/k. But from the standpoint of technical evaluation they are at least a hiccup.

One might take a specific distribution of maximum level versus frequency into account, as it is demanded by a typical music program. To some accuracy it can be discribed as this:

https://www.hifi-selbstbau.de/images/stories/grundlagen/waveana/Track260MaxL.png

So, the demand in the deepest bass region is considerably less than mostly anticipated. Demand in lower treble is way less than in the mids. But even with the lowest levels the ribbon distorts in the 2..3% region.

A second irregularity is the interference that comes from the baffle dimensions. The discontinuity in the dispersion comes up around 3..4kHz.

And third the compression has a hot spot exactly there.

I think the ribbon is clearly the archilles heel for the overall design. I assume it is the most expensive single part. Does it make sense, really?

Seems a bit nit-picky. Why don’t you design a better speaker, you know, show him how it’s done? You seem to have some strong opinions (negative) about a speaker you have never heard and have no intention of hearing. I look forward to hearing about your designs.

 

[hardisj]

Lots of costly speakers used curved sidewalls, it helps with performance. To have the same performance with a traditional box cabinet would likely mean thicker panels and more robust bracing.

Besides just internal performance, I wonder how the curved panels affect the frequency response, as it slightly adds to what beveled/rounded baffle edges accomplish.

Well, one thing I noticed was the impedance sweep has no indication of resonances. To date, every square box speaker I have tested does. I can't help but wonder if the curved enclosure is the driving force here (that, and good driver selection would be another positive).

 

[q3cpma]

Seems a bit nit-picky. Why don’t you design a better speaker, you know, show him how it’s done? You seem to have some strong opinions (negative) about a speaker you have never heard and have no intention of hearing. I look forward to hearing about your designs.

Don't go "you can't criticize if you don't do better", it's childish. Anyway, I completely agree with the two main concerns: distorsion is way too high in the important band (I'd say 300-3000 Hz) and ribbons like these are nothing but expensive gizmos, when you can get a similarly wide dispersion with a 3/4" dome tweeter with no real drawback.

For example, I found the Scanspeak R2004/602000 (or D) or Tymphany NE19VTS-04, while looking around a bit:
https://www.scan-speak.dk/product/d2004-602000/

https://www.scan-speak.dk/product/r2004-602000/

https://www.tymphany.com/transducers/ne19vts-04/

 

[hardisj]

I don't disagree that, technically, the distortion is of concern. And I still haven't listened to the speakers since I tested them to see if I can hear what I know was measured (because, again, I never measure before I listen). I think if someone were to put the same performance speaker in front of me with one having lower distortion figures than the other then it would be obvious that I would want the lower distortion speaker.

I was really impressed with this speaker and I can honestly say that I didn't hear anything that seemed to scream obvious distortion. However, when I listened to the Neumi BS5 bookshelf speaker (link here), I did hear distortion in the midrange:

And I had this to say in my subjective evaluation (again, as always, made before I measured the speakers):

I noted midrange distortion at ~ 90dB (at 11 feet) in both Jim Croce’s and John Mayer’s tracks. I wasn’t sure what this was when I listened the first time, but the data clearly shows an increased level of distortion smack in the middle of the midrange. I went back through a final round of listening after I saw the data and on the “He Mele No Lilo” track, at the end, I could hear distortion in the singer’s voice. It seems I noticed this distortion in male vocals.

Comparing apples to apples:
At the 90dB stated above, the Neumi measures at about 1-2% THD in the midrange. The Philharmonic BMR measures at about 0.50% THD. Maybe that was the reason I didn't notice anything objectionable with the BMR but I did with the Neumi.

It is obvious, however, the BMR exhibits a much higher distortion set above 1kHz. But, again, I didn't note anything that I attributed to distortion. I did note things that were "different" in the treble region... and maybe the distortion is the cause. But I chalked it up to the dispersion or the resolution of the RAAL. Is it possible the "resolution" was an increased THD? Maybe. Or does masking play a role here in covering up the HF distortion?



With all that said, the compression is the part that bothers me more than the Distortion %.

 

[R Swerdlow]

This discussion about levels of distortion in the lower range of the BMR's tweeter ignores an important point. What percent distortion is audible?

I've re-posted the NRC measurement of the BMR speakers distortion (THD+Noise, expressed as SPL) where the speaker's frequency response, at roughly 90 dB is shown on the same graph.

At 2.5 kHz, the speaker produces about 90 dB, and the THD+N is about 58-60 dB (as measured by eyeball). The THD+N is 28-30 dB quieter. In my own experience when two sounds are played at the same time, and one is at least 25 dB louder than the other, the ear/brain tends to ignore the quieter sound.

At worst, at the slight dip at 3 kHz, the speaker's output is 86 dB, and the THD+N is about 58 dB. That difference, 28 dB, is still enough to easily ignore the distortion.

 

[aarons915]

The suggestion that the Raal is the achilles heel in the BMR is absolutely baffling to me, and I can only conclude this is one of those cases where the things being measured (distortion, vertical dispersion) have absolutely no correlation to the audible sound you hear, or at least the average listener's preference for that sound. I'm fairly sure I've read every review or forum post about the BMR that can reasonably be found via a google search. And aarons915 (who posted earlier in this thread) is literally the only person, ever, that I've seen complain about the Raal or about this speaker sounding too bright.

Just to clarify, I don't think the RAAL is bright, I just felt the BMR as a whole was a bit bright in my small room, I wish I had a larger room to test the theory that it's related to the close sidewall reflections but I didn't. I tried the Mini Phil's before the BMR and felt they were a tad laid back so I don't believe it's related to the tweeter, the culprit to me seems to be in the range of the BMR midrange and the 1-3k range do seem very strong in this speaker. I never heard anything objectionable in either speaker that sounded like distortion but I also never listen anywhere close to the levels the distortion measurements are taken.

 

[Selah Audio]

Here's a distortion curve (2nd and 3rd harmonics) of the RAAL 70-10D in one of my designs. This was referenced to 100dB @1K and .5M distance, the equivalent of 94dB @1M.

 

[q3cpma]

This discussion about levels of distortion in the lower range of the BMR's tweeter ignores an important point. What percent distortion is audible?

I've re-posted the NRC measurement of the BMR speakers distortion (THD+Noise, expressed as SPL) where the speaker's frequency response, at roughly 90 dB is shown on the same graph.

At 2.5 kHz, the speaker produces about 90 dB, and the THD+N is about 58-60 dB (as measured by eyeball). The THD+N is 28-30 dB quieter. In my own experience when two sounds are played at the same time, and one is at least 25 dB louder than the other, the ear/brain tends to ignore the quieter sound.

At worst, at the slight dip at 3 kHz, the speaker's output is 86 dB, and the THD+N is about 58 dB. That difference, 28 dB, is still enough to easily ignore the distortion.View attachment 74144

Percent of THD isn't very useful though. You can't talk about masking without looking at the different THD components or using some kind of weighting like Geddes' metric. Seeing that the 3rd harmonic is still at 2.5% in that tweeter low end makes it more worrying.

 

[q3cpma]

Here's a distortion curve (2nd and 3rd harmonics) of the RAAL 70-10D in one of my designs. This was referenced to 100dB @1K and .5M distance, the equivalent of 94dB @1M. View attachment 74179

Well, that's another story. Do you think the different tweeter model is the cause here?

 

[zermak]

Here's a distortion curve (2nd and 3rd harmonics) of the RAAL 70-10D in one of my designs. This was referenced to 100dB @1K and .5M distance, the equivalent of 94dB @1M. View attachment 74179

That is indeed very smooth but if I am not wrong it is almost 2x the price of the ribbon used on the BMR.

 

[Dennis Murphy]

I've always been sceptical that PIR is representative of the speaker's tonality or timbre. The research seems to indicate that we perceive these mostly in the direct sound (i.e. on-axis/listening window), and the off-axis data is mostly only relevant for spaciousness attributes (and consistency of reflected response). I know that some people on this forum swear by PIR and believe it subsumes everything else, but that's clearly not what @Floyd Toole thinks, it's not what the Olive Preference Rating model thinks, and it's not supported by the research, either.

If I get asked to judge a speaker's tonality or timbre from measurements, the Listening Window would be my best bet, not PIR.

This certainly comports with my experience. On a related matter, the centered drivers on the BMR do make for some diffraction hills and valleys on axis, but these pretty much go away in the listening window. I listen to the BMR's with no toe-in so that the first arrival sound is the flattest.

 

[Selah Audio]

Well, that's another story. Do you think the different tweeter model is the cause here?

The 70-10D preceded the 64-10 that's used in the BMR. The transformer in the 64-10 is different in that it's used to shape the response and simplify the passive crossover design. In order to lower the cost the 64-10 doesn't have a replaceable ribbon and some other changes were made.

I used one of the 64-10 tweeters in a center channel for an owner using the BMR as left and right speakers. Unfortunately I didn't test the distortion but I was keeping the crossover points close to those used in the BMR.

 

[Selah Audio]

That is indeed very smooth but if I am not wrong it is almost 2x the price of the ribbon used on the BMR.

It is more expensive but I posted it as an example that a ribbon can be used and exhibit low distortion.

 

[Dennis Murphy]

(The link to the flat-pack leads back to Your home page.)

The ribbon, sealed or not dictates a higher x/o frequency, but still it distorts considerably. We have uneven directivity in the vertical, the possible mechanical vulnerability, the high price. For not more than a tiny bit of wider dispersion in the tops of the hights.

The BMR again dictates a higher x/o due to otherwise too high of distortion figures. Even bigger problems in respect to vertical directivity.

The woofer is expensive, especially when compared to more contemporary offers. With a more competent mid the x/o would be more relaxed, the woofer could have been way cheeper. Alltogether with less intermodulation, where the woofer is always the main contributor.

So, it seems funny, but the measurements don't look that bad. Two things appear less fortunate to my eye.

- The curved sidewalls are inacceptable, design-wise.

- The distortion, whether perceptible or not, must not be. One might argue, that these aren't that bad, because of and so forth, o/k. But from the standpoint of technical evaluation they are at least a hiccup.

One might take a specific distribution of maximum level versus frequency into account, as it is demanded by a typical music program. To some accuracy it can be discribed as this:

https://www.hifi-selbstbau.de/images/stories/grundlagen/waveana/Track260MaxL.png

So, the demand in the deepest bass region is considerably less than mostly anticipated. Demand in lower treble is way less than in the mids. But even with the lowest levels the ribbon distorts in the 2..3% region.

A second irregularity is the interference that comes from the baffle dimensions. The discontinuity in the dispersion comes up around 3..4kHz.

And third the compression has a hot spot exactly there.

I think the ribbon is clearly the archilles heel for the overall design. I assume it is the most expensive single part. Does it make sense, really?

I can honestly say I don't agree with anything you've said. "The curved sidewalls are inacceptable design-wise"?? The distortion, whether perceptbile or not, must not be" ??? Don't get me started. But for the record, the tweeter is not the most expensive driver. It still won't be when I replace the 8545 woofer with the SB Acoustics Ceramic. I'm using this particular RAAL because it provides the kind of sound I like. And it does that because of its broad dispersion and flat and extended response. I've done a version with the much more expensive 70-10, and I couldn't hear or measure any advantage. I've done everything I can think of to keep the price of the BMR down without sacrificing performance. if you can build a speaker that sounds as good, goes as deep, and can be sold for less, I urge you to join the fray. (But I hope you have $1M in the bank to cover losses )

 

[R Swerdlow]

Percent of THD isn't very useful though. You can't talk about masking without looking at the different THD components or using some kind of weighting like Geddes' metric. Seeing that the 3rd harmonic is still at 2.5% in that tweeter low end makes it more worrying.

Your response doesn't address my question. What level of distortion, expressed as a percent value, is audible? It makes little difference which harmonic, 1st, 2nd, 3rd, etc. is involved. I understand that frequency and SPL matter, but how much distortion is enough to be audible? And, while we're at it, how much distortion is not only audible but objectionable?

I ask this because various ribbon tweeters are widely panned because of measured low frequency distortion. But few if any ribbon tweeter owners object to their sound, when they're properly implemented into a good speaker design. In fact, the sound qualities of ribbon tweeters, especially the RAAL models, are widely praised.

Of course, this is anecdotal evidence, it doesn't prove or disprove anything. But it does suggest that measurements of low frequency harmonic distortion of ribbon tweeters – alone – do not explain why they are or are not accepted.

 

[q3cpma]

Your response doesn't address my question. What level of distortion, expressed as a percent value, is audible? It makes little difference which harmonic, 1st, 2nd, 3rd, etc. is involved. I understand that frequency and SPL matter, but how much distortion is enough to be audible? And, while we're at it, how much distortion is not only audible but objectionable?

I ask this because various ribbon tweeters are widely panned because of measured low frequency distortion. But few if any ribbon tweeter owners object to their sound, when they're properly implemented into a good speaker design. In fact, the sound qualities of ribbon tweeters, especially the RAAL models, are widely praised.

Of course, this is anecdotal evidence, it doesn't prove or disprove anything. But it does suggest that measurements of low frequency harmonic distortion of ribbon tweeters – alone – do not explain why they are or are not accepted enthusiastically.

It does adress it, because the question has no single number answer, as masking is frequency dependant, which means H2 and H3 don't have the same audibility limit.

 

[Dennis Murphy]

It is more expensive but I posted it as an example that a ribbon can be used and exhibit low distortion.

I've tried the 70-10 in a number of configurations, including my Philharmonic 3 crossed well above the factory's suggested point, and distortion has always exceeded 1.5% at 90 dB, one meter. And that's based on of tests on dozens of production speakers. So I find your measurements very surprising. Perhaps you're using steeper slopes than the suggested 4th order acoustic?

 

[zermak]

It is more expensive but I posted it as an example that a ribbon can be used and exhibit low distortion.

I see and well I figured out that better options are out there but probably not for the same price and well that ribbon is definitely an upgrade over the one used here if we consider the distortions graphs (but indeed it has a higher price).
I am sure Mr. Murphy chose a ribbon over a dome because of the orizontal dispertions and probably for the simpler implementation on a flat baffle.

 

[Dennis Murphy]

Thank you for reply. I saw the review of BMR on hificompass, the distrotion is already more than 1% at 500 Hz, so that's what my concern was. This review showed better distortion than I expected, the crossover is perfect that the lobing is not visible even with 40 degree off vertically. I have seen the facebook post regarding new driver, they said the mid voicing is a bit different for the new one, what is your opinion on the new one?

Are you sure that's the same BMR driver? Do you happen to have a link to the test--sounds interesting. Thanks