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Philharmonic BMR Review
I finished reviewing the famous Philharmonic BMR speaker. It's way too much to copy and paste here (image tags kill me!) so here is a link:
https://www.erinsaudiocorner.com/loudspeakers/philharmonic_bmr/
Comments
Very thorough review. Well done. Enjoyable.
That's great Erin. I had heard this in Axpona one year and liked it a lot...
I'm sure many of us can equal that performance 😉
Interesting speaker, I'd never think to pair up a $20 BMR with a RAAL.
I didn't get this part. Are you looking to run the BMR full range for the highs?
However, I would like to hear what these speakers can do if one was to cover the tweeter so as to make it a small square rather than as tall as it is. That would theoretically bring the beaming point up to match the horizontal dispersion pattern and I would really be interested to see how that additional vertical window of dispersion would help (or potentially hurt) these speakers.
I'v been playing with those BMRs they have a lot of potential. No low end.
Thinking about pairing a BMR with a woofer crossed at about 400hz. Curious where these cross at.
which BMR? I got one pair too... interesting little things. I liked @jhollander implementation of the 3.5 incher - that had a lot of bass with f3 in the high 40's low 50, good little woofer.
I mean, take the rectangular radiating area of the RAAL and make it a square. That way the directivity in both horizontal and vertical are the same as opposed to having a very wide radiating area horizontally but a very narrow one vertically.
I mentioned it in the review:
"from what I can tell, the crossover point between the woofer and the midrange is about 550Hz."
I'm basing this on the nearfield plot:
The Raals in the Cherry Pi's came with little foam blocks that change the vertical dispersion. I did some measurements as I recall but have no idea where they are.
Edit-I found them in this post. techtalk.parts-express.com/forum/tech-talk-forum/59864-raal-70-10-deflector-pads-effects
Ron
The BMR are very wide dispersion, reducing the Raals horizontal dispersion would it create a directivity mismatch? Not sure I understand what I said....
what is relation between the ribbon height, width and horizontal and vertical directivity? and does more surface area mean they cross lover and have more sensitivity, but that affects directivity?
@ani_101 Have a look at the measurements. The RAAL horizontal directivity is wider than the BMR:
When it comes to rectangular drivers, the generalization would be that a driver 1" wide by 4" tall would have the directivity of a 1" round driver horizontally, and the directivity of a 4" round driver vertically. Roughly anyway...
I discuss this in the review.
"Additionally, the RAAL is quite directional, vertically, due to its tall orientation. Therefore, it “beams” at approximately the frequency that equals the radiating height (70mm; 2.75 inches). Using the speed of sound and half-wavelength you can calculate the beaming point for this dimension as ~2.5kHz (SoS = 13500 under standard conditions: SoS/2/2.75 = 2449 Hz). "
A dome tweeter radiates the same in all directions because it's a circle. A rectangular speaker has a different vertical and horizontal radiation pattern because it becomes directional at different frequencies. @dcibel nailed it in his reply above.
And just to be clear, I said to reduce the height to make it match the width (maybe by adding a very thin piece of plastic or something to the inside of the faceplate) in order to decrease the radiating dimension vertically which would push up the beaming point.
You know where to find me.
Thanks Dcibel and Erin, i sort of got it backwards and thinking the RAAL wasn't matching the BMR.
Question on the reducing the horizontal opening of the tall ribbon - wouldn't this cause internal reflection?
I'm not a "challenge accepted" guy, more of a... I've heard a shitload of speakers across every price point between commercial and diy... When someone says " No matter what your experience level or desire to build, I think these speakers are a no brainer for their price..."
Well, clarify that shit, Erin. Am I wasting my time?
I thought it was quite clear: this speaker holds a lot of value either in DIY form or purchased complete form.
You took my quote wrong. It wasn't at all a "you can't DIY better for the price". It wasn't a challenge to the DIY community (who, in large part, wouldn't be looking at this speaker as a purchase anyway). It was a "hey, you can buy these as a kit and put it together or you can buy them complete and either way they are a great value". I shared the results here because Dennis is "one of us" and I thought some people might like to see accurate data for it.
So, back to my previous reply to you, if you have a design you're proud of and you want to see how it objectively stacks up against this one then you can message me and we can try to work something out. But let's leave the ego at the door. I do this for fun. To teach. To learn. To provide insight. Not to get in to speaker turf wars.
Yes. I mentioned the "thin plastic" part above... it would be more of a "let's see how this changes things". I'm not advising anyone run out and do that on their speakers. But, if making that rectangle in to a square indeed increased the vertical response window then maybe there's a way to make a new faceplate. Dudes these days can 3D print and CNC anything, it seems.
Nice review.
+1db 4k to 8k, very detailed sound........I know that some of you will know what I'm thinking.
By the way, I don't mean anything negative toward the philharmonic speaker in that statement. It is obviously a well designed speaker.
Dennis has been known to place a lift in the upper treble of about a dB. It sounds more natural and realistic to him because of playing the violin.
Honestly- I've heard those BMR drivers in another design and did not care for them at all. Another one sounded pretty darn nice. Good examples are Bill's Totally Flat, and the larger woofer in John's little green boogers. It definitely shows implementation still needs to be concise. Dennis' designs generally sound pretty good too- and he knows his stuff.
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