Philharmonic Audio BMR Speaker Discussion

[ribosradagast]

Whelp, here goes nothing. Just ordered the both kits, because you only live once

 

[bogart]

Whelp, here goes nothing. Just ordered the both kits, because you only live once

I admire your gusto! What's your plan for cabinet surface finish?

 

[ribosradagast]

I admire your gusto! What's your plan for cabinet surface finish?

I was just gonna cover it in one of the gel-based General Finishes that they recommend on the speakerhardware site:
https://generalfinishes.com/wood-finishes-retail/oil-based-wood-stains-sealers/gel-stains

Maybe I'll round over some of the corners as well, but unsure. Never done a project like this before...

Regarding "gusto," it's certainly deflating to hear from Leland (speakerhardware guy) that he's super slammed with orders so this one will take at least 3 weeks for him to get to.

 

[bogart]

I was just gonna cover it in one of the gel-based General Finishes that they recommend on the speakerhardware site:
https://generalfinishes.com/wood-finishes-retail/oil-based-wood-stains-sealers/gel-stains

Maybe I'll round over some of the corners as well, but unsure. Never done a project like this before...

Regarding "gusto," it's certainly deflating to hear from Leland (speakerhardware guy) that he's super slammed with orders so this one will take at least 3 weeks for him to get to.

Sounds like you have time to grab some junk plywood and practice your finishing on something that won't sit in the living room
Oh, and in case you're building the crossovers too, you can practice your soldering. Lucky you - you'll be all skilled up by the time they arrive.

 

[DeruDog]

I'm also considering the BMRs. Top of my list followed by the DXT-MON. I have also considered going active but came to the same conclusion as others: that Dennis' design is worth using all on it's own.

For the center, Dennis recommends a third Philharmonic BMR lying on its side with the tweeter rotated 90 degrees. I might do this and also build an experimental box with the Tweeter over the BMR to see if that works a little better … or worse. So tempted to pull the trigger immediately, but I have a lot of projects to finish around the house before I get to this.

 

[GelbeMusik]

… share their thoughts and impressions.

I think the use of a ribbon has fallen out of time. Looks/feels fancy, but ...

I've never seen a distortion plot of these. I wonder why. The BMR tech has its merits, but ...

The spinorama isn't that good. It has its pitfalls, especially with the very wide dispersion of the BMR in the mids, that is not particularly consistent. There are way better implementations towards the spinorama norm.

Question 1: Go active?

No. To make sense the overall design shall take advantage of the active, better digital control from the ground up. This would imply a total redesign.

... whether these are a good candidate for fully active speakers using Hypex DSP amps (such as this 3-way option).

See above, an utter waste it would be.

Before to start DIY today, with currently given quality demand, first to do is to get used to measurement with microphone. Only later You might feel to do better than the industry. And start the woodwork. Measurement and correction using some digital EQ like miniDSP and other. Tonal balance to Your personal (!) preference, adopted to room acoustics, integrating subs maybe.

 

[Ericglo]

I think the use of a ribbon has fallen out of time. Looks/feels fancy, but ...

I've never seen a distortion plot of these. I wonder why. The BMR tech has its merits, but ...

The spinorama isn't that good. It has its pitfalls, especially with the very wide dispersion of the BMR in the mids, that is not particularly consistent. There are way better implementations towards the spinorama norm.

Are we looking at the same measurements? The only ones I have seen are on Audioholics. James Larson even mentioned it was the most neutral speaker he has ever measured.

 

[GelbeMusik]

James Larson even mentioned it was the most neutral speaker he has ever measured.

Aha? Do You think I need the comment of James Larson to understand the curves?

 

[Ericglo]

I didn't put his comment in there to understand the curves. I said he wrote that it was the most neutral speaker he has measured. I haven't looked at every speaker he has measured. According to Audioholics, he has 41 speaker reviews. I would guess he has measured more speakers than the ones that have been reviewed.

Looking at the measurements, I saw what you have pointed out. That being said, it still looks good.

 

[napilopez]

Aha? Do You think I need the comment of James Larson to understand the curves?

View attachment 66167View attachment 66168

I've got to disagree with your interpretation though. Dennis has stated he designs his speakers to be positioned with little to no toe in so rising treble isn't much of an issue and arguably preferable. And imo having a power response dip /do narrowing lower in the frequency range is better than the sensitive upper mids almost every other speaker does. Additionally I believe some unevenness can be forgiven in wider directivity designs louder reflections seem to trigger the precedence effect more.

I know you don't like ribbons but I reiterate there are few speakers with directivity so wide, let alone at this price. You could use a smaller dome tweeter or carefully sculpted baffle, but I've not seen many speakers with comparable directivity in commercial designs.

 

[GelbeMusik]

... isn't much of an issue and arguably preferable ... is better than the sensitive upper mids ... I believe some unevenness can be forgiven in wider directivity designs louder reflections seem to trigger the precedence effect more.
... let alone at this price. ... smaller dome tweeter or carefully sculpted baffle, but ...

As soon as I read "sensible upper mids" I long for my "book". I think there isn't any evidence in the Toole to backup this theory. Neither is elsewhere. Otherwise it would be necessary to weight deviations from "tilted somewhow" according to frequency range in "the metric". There isn't, so: counterevidence: no "sensitive upper mids".

The "precendence effect" does wonders? With me it only triggers questions, many questions. First I think that precedence is not about reflections: read the "book"! To the contrary it is about a first signal taken as the information as which inclination some source of sound has, regardless of the echoes. How could wider dispersion trigger this?

Ja, the price ...

I don't think that the effort to implement a 3/4 inch tweet is comparable to make sculptured baffle. It costs even less! First and most, a sculptured baffle doesn't help dispersion up high.

I don't know if it is enough "science" to read the Toole and rearrange all one might have read elsewhere along those lines. Who knows what she might have read elsewhere. And, how the logic, deriving conclusions I mean, goes in science. I feel that as an educated scientist one might question the relevance of discussing sensible mids triggered by precedence on priceless sculptured baffles. The wide dispersion baffles me.

 

[napilopez]

As soon as I read "sensible upper mids" I long for my "book". I think there isn't any evidence in the Toole to backup this theory. Neither is elsewhere. Otherwise it would be necessary to weight deviations from "tilted somewhow" according to frequency range in "the metric". There isn't, so: counterevidence: no "sensitive upper mids".

The "precendence effect" does wonders? With me it only triggers questions, many questions. First I think that precedence is not about reflections: read the "book"! To the contrary it is about a first signal taken as the information as which inclination some source of sound has, regardless of the echoes. How could wider dispersion trigger this?

Ja, the price ...

I don't think that the effort to implement a 3/4 inch tweet is comparable to make sculptured baffle. It costs even less! First and most, a sculptured baffle doesn't help dispersion up high.

I don't know if it is enough "science" to read the Toole and rearrange all one might have read elsewhere along those lines. Who knows what she might have read elsewhere. And, how the logic, deriving conclusions I mean, goes in science. I feel that as an educated scientist one might question the relevance of discussing sensible mids triggered by precedence on priceless sculptured baffles. The wide dispersion baffles me.

Forgive me if I misunderstand your post, or maybe I was unclear.

I made a typo with saying just sculpted baffle. I meant baffle and waveguide. Second I said "imo", or in my opinion, so I didn't mean to mention anything as fact. I was offering an alternate interpretation of the spinorama since you said the spinorama "isn't that good." I think it is quite good considering the design goals, and it's fine if you disagree.

Regarding the precedence effect, we must have read different books. The precedence effect is about the relationship between the direct and sound and later arrivals. The original Haas study used two sources of equal loudness, but in rooms, the precedence effect means reflections, of course. From an evolutionary perspective it appears to have developed to make sense of sources and lovalization in reflective spaces.

Section 7.6.5 of the third edition, for instance, talks about how reflections above the detection threshold can contribute to a pleasant " 'image broadening,' or apparent source width (ASW), widely liked qualities in sound reproduction as they are in live performances."

Indeed, this is the point of wide directivity designs - they present a large soundstage. That is what I meant by "triggering the precedence effect more."

Toole goes into more detail in "Loudspeakers and Rooms for Sound Reproduction—A Scientific Review 2006", which is mainly a review of previous research of the precedence effect, and we get this image:

You can see how early reflections contribute to the aforementioned pleasant image spreading. The paper later goes on to imply that people seem prefer reflections to be louder than this.

Of course, we also know that it helps for the reflected sound to have similar spectra to the original sound as well.

Where I take a little liberty in interpretation is in saying that in wide directivity designs, it is okay for the off axis to be a bit less than 'perfect' because the of the higher reflected SPL still triggering the "pleasant image broadening" aspect of the precedence effect. In other words, I'm willing to take a slightly uneven wide directivity design over a perfectly even narrow directivity design (within limits, of course). Toole 1985(7.4.2 In the book) seems to support this too.

As for the use of ribbon vs a smaller tweeter/distortion/etc I do take your point, but I repeat that it is very difficult to find designs with similarly wide directivity in this price range. We can debate about whether a ribbon is optimal or necessary, but the fact does remain that similarly wide directivity designs are rare in the price bracket.

As for 'sensitive upper mids' I admit that is largely my opinion. While I have not seen recent research associating preference with smoothness along different perceptual bands, the Olive preference paper clearly acknowledges this is a possibility, citing earlier work by Klippel:

"Klippel’s model uses a weighted combination of the free-field on-axis response and the measured or predicted in-room response. This would explain why both models produce good correlations with subjective results. One difference is that Klippel uses a perceptual-based critical band model to calculate loudness errors in a program reproduced through the loudspeaker. Our model may be further improved through the addition of a perceptual model."

So while I could be totally wrong about where it is better or worse to have anomalies, Olive himself clearly acknowledges a possibility and perhaps a likelihood that different frequencies should be weighed differently. After all, the preference model already ignores data after 12 or 16kHz, depending on the metric, even though some people are sensitive to these regions. Another reason for me not liking the usual 2K dip is this is a region that is already timbrally compromised in stereo reproduction by interaural crosstalk.

So you're more than welcome to disagree with me, but I'm not just pulling my assessments out of a hat either.

 

[GelbeMusik]

Apologies for my rant. I don't say the BMR is faulty. It has its drawbacks, which I would have avoided. That is it all about. On the other hand, besides being a perfectionist, I actually feel bad about all that stereo science, as an aftermath to its invention. With this I am, You won't believe, completely with Dr. Toole. How long did I hunt after the stereo nirvana? Too long--what a waste of precious time! Think alone of the recording techniques which are all but true to the source.

So, I'm a bit sensitive against buzz words, You might admit, like "sensitive upper mids" and such.

Especially, back on topic, the presumably most expensive part of the BMR seems to be the most disputable one, namely the ribbon. Right, it's not available outside the box? Why not a technically sufficient 3/4" dome of (?) tenth of the cost? Less problems: a common, well predictable dispersion, robustness, interchangeability, less distortion, what ever, and waveguided the end of all desires.

Now that the desicssion is made, go ahead. It's about fun. It would be tastelessly decadent to not live up to that goal.

 

[Ericglo]

Regarding this speaker and its ribbon, I believe Dennis has explained his preference for it in other places. Maybe he will do the same here.

Also, IIRC Dennis differs from Toole in certain areas. Again maybe he will explain here.

 

[GelbeMusik]

Regarding this speaker ...

Spoiler: I strongly recommend to get You a microphone. You need a quality check after, buy ready or built yourself. Since You mentioned the DIY route, as I said earlier, this little device together with a computer is kind of the key to better sound. More than any particular speaker. First You adopt to some external so called house curve, e/g the Harman tilt, then You deviate, maybe, to please Your own taste and record collection.

Toole, if I get him right, "there is no ideal".

 

[DeruDog]

While I enjoy the commentary, I wonder if there is a speaker that measures better at under $500 a piece. Surely at this price there will be imperfections and compromises, but to my eye it is very good in comparison to competitors at this price.

 

[bogart]

While I enjoy the commentary, I wonder if there is a speaker that measures better at under $500 a piece. Surely at this price there will be imperfections and compromises, but to my eye it is very good in comparison to competitors at this price.

I will love to know the answer to that. The BMR caught me completely by surprise; it’s not something I had crossed paths with before. Makes me wonder what else is hiding!

 

[Sancus]

While I enjoy the commentary, I wonder if there is a speaker that measures better at under $500 a piece. Surely at this price there will be imperfections and compromises, but to my eye it is very good in comparison to competitors at this price.

Well that's the DIY price, as far as I can tell they're currently $1200/ea from Salk and that's the only source of completed ones? I have no idea what comparable DIY designs there are out there, if any.

Certainly if I was looking for a great "wide directivity" speaker to try against the Kef R3 or something, BMR looks like one of the best picks out there. Availability seems like the only real issue(not sure what lead times are like from Salk).

 

[Dennis Murphy]

All the talk on the Affordable Accuracy Monitor thread about the BMR piqued my curiosity and got me reading about this very interesting speaker. It seems to have a really excellent reputation and measures very well. This has also been my introduction to @Dennis Murphy - I'm so grateful for folks like you engaging so generously with folks interested to learn more about your work and enjoy it. Thank you, sir!

I'd like to start a discussion of this speaker - inviting folks who have one / heard them / etc. to share their thoughts and impressions.

Thanks very much for starting this thread Bogart. I hope it will provide some useful and polite correspondence. I think that, if nothing else, my design raises interesting issues. A full reply to all of the points raised so far would would require to much space and effort right now, so I would just like to make some bullet points.

1) Concerning my choice of the RAAL ribbon: The most obvious alternative for me would have been the 0W1 3,4" dome. It actually is considerably more expensive than the RAAL and its dispersion isn't as wide up high. It can be crossed lower than the RAAL, but that wasn't a consideration in this 3-way design. I happen to prefer the sound signature of the RAAL, which has less energy in the sssssssssssssssssss region and is more transparent at the very top. The same is true in a comparison with other domes I've tried. THD is similar to the 0W1 up to around 9 kHz, where the RAAL does go above 1% at high SPL levels. Since the first harmonic of 9 kHz is 18 kHz, I'm not too concerned about whether there are the remnants of the 9 kHz fundamental up there.

2) Although I have great respect for the Spinorama protocol and the research that lies behind it, I am very wary of attaching biblical validity to all of the components. I would much prefer a speaker with very broad but not perfectly even dispersion to one that had perfectly controlled dispersion over a narrower frontal arc, even though that speaker might achieve a higher Spinorama preference score. In general, when interpreting Spinorama scores, I look at the linearity of the early arrival measurements and at the general breadth of dispersion, even though there might be a peak or a dip in the response past, say, 45 degrees off axis. I guess I also look at the predicted room response, although I don't really understand how this is generated. For the record, the BMR does not actually measure with an elevated on-axis treble as it would appear from the Audioholics plots. My measurements always track the NRC's anechoic chamber measurements for the same speakers, and their results for the BMR, as well as mine for the Audioholics review sample, are flat in the treble. That's just a matter of mic calibration, and it's not of any practical significance in any event.

3) I think you can understand that I am not entirely happy with the current availability options for the BMR. They were best I could do under the circumstances. Due to a number of factors, including the favorable impact of the trade war and virus on the willingness of Chinese suppliers to meet the needs of small buyers like me, it looks like I will be able to reintroduce the Chinese BMR's with a wider choice of cabinet finish options in the Fall. However, it won't have the same woofer, and it won't be clearly better than the current kit version. Also, tariffs and taxes will push up the price, so there's no reason not to purchase the kit if you want to save money and you enjoy DIY. In addition, I will be receiving a pair of Purifi 6.5" woofers shortly. They are the same size as the Scan 8545 (and even uglier) and have the potential to provide cleaner and deeper bass, albeit at a considerably increased cost. If I think the Purifi's are worth price, my plan is to offer a new kit version of the BMR, and a completed version with custom cabinets through Jim Salk. All of this is uncertain at this point, and any resulting kit or Salk version will be considerably more expensive, so again none of this should make the current kit or Salk BMR a bad investment. I just don't want to blind side anyone with a fait accompli in 4 or 5 months. ( I'm not planning any changes in the midrange or tweeter selections.)

 

[PNWer]

I'm also considering the BMRs. Top of my list followed by the DXT-MON. I have also considered going active but came to the same conclusion as others: that Dennis' design is worth using all on it's own.

For the center, Dennis recommends a third Philharmonic BMR lying on its side with the tweeter rotated 90 degrees. I might do this and also build an experimental box with the Tweeter over the BMR to see if that works a little better … or worse. So tempted to pull the trigger immediately, but I have a lot of projects to finish around the house before I get to this.

I use a vertical BMR as the center speaker. At the time this could be ordered done by Salk with a front port.
If this fits your layout you can ask Dennis Murphy for the plans of the speaker cabinet.