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Old 23rd February 2012, 02:02 PM   #31
theJman is offline theJman  United States
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Originally Posted by Overkill Audio View Post
I think the BMR 's are still only available to OEM's in MOQ of 100 units.
Yea, I was afraid it was going to be something like that. I've been in contact with HiWave for about a year now, because they're supposed to release 3.5" and 6.5" BMR drivers. But the shipping date keeps getting pushed out, so ever few months the date gets moved to some time in the future. I've grown frustrated waiting, so I started to look around. That's how I stumbled upon CSS, but it appears that might not be an option either.
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Old 23rd February 2012, 02:37 PM   #32
theJman is offline theJman  United States
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Some pics of the 8 driver array on wall.
That looks cool as hell, and I bet it sounds fabulous. Not sure I'd want a window right behind my TV though - seems like it could make it difficult to see the picture. BTW, where's your center?

My only exposure to BMR is a pair of Cambridge Audio Min 10's I have hooked up now, which were lent to me by a friend. Imaging and clarity from these tiny speakers just amazes me. The only thing lacking is strength in the lower midrange, where they can sound a bit thin. That's precisely why I want to build a set using larger drivers; once the midrange issue has been resolved I think it would be very difficult to find any fault with the sound.
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Old 23rd February 2012, 05:20 PM   #33
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Default BMR Line Array sound

Hi Jman,

I also found the lower midrange to be a bit weak with the small BMR's.
The 4.5 inch really is the "Goldielocks" drivers as it still has a lovely high end but enough Sd to move some air when you need to hear percussion and left hand piano, cello etc.
Back in 2008 I found that a pair or 4 drivers per speaker was required to reach high enough SPL's in typical rooms. Both the flat on wall models were ported to help boost the bass and also had passive crossovers.
The crossovers were designed by Chris Ellis, one of the BMR drivers designers and a full on audiuo genius so as good as it gets with passive.
There is still a big step up in performance when you go sealed, DSP active crossovers and Eq. The BMR is a perfect match with DSP and efficient power amps.
My 8 driver line array is EQ'd to enrich the lower mids and then has a Linear Phase 96dB per octave crossover at 100Hz.
The main compromise I made with this design is the centre to centre driver spacing to achieve the curvy asthetics. In theory it suffers from comb filtering but real world in room reflections even out a lot of the nulls and peaks.
The speakers have such fantastic imaging ( over the whole 4 seater sofa )that I dont need a centre channel! Two channel sound staging is rock solid from almost anywhere in the room and the sound from the next room is very much " who is playing piano in the lounge?"
I might be up for a group buy or BMR's in a couple of months, a few guys have already asked me if I get them some drivers. They are very light so shipping is low cost.

Cheers
Derek.
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Old 23rd February 2012, 05:51 PM   #34
sreten is offline sreten  United Kingdom
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Originally Posted by Overkill Audio View Post
and then has a Linear Phase 96dB per octave crossover at 100Hz.

Derek.
Hi,

Living up to your moniker then ? There is not much linear phase about
a 96dB(!?)/octave x/o without some serious digital time manipulation.

I remember reading about high order digital linear phase x/o's and
their problems but I cannot recall the details, 96dB seems overkill.

rgds, sreten.
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Last edited by sreten; 23rd February 2012 at 06:00 PM.
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Old 23rd February 2012, 05:52 PM   #35
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Naim Ovator uses a BMR. There were some measurements published on both in Stereoplay.
The S 600 had strong resonances at 2kHz but the smaller S 400 had none (at least in the range of the measurement - 10kHz). I have not heard them and I am wondering who is manufacturing their BMR units.
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Old 23rd February 2012, 08:18 PM   #36
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Default Naim BMR

Hi Guys,

I am not sure who makes the Naim BMR's, also I am not sure there is a great deal of difference between the different suppliers, all variations on the same theme really.
Size of the BMR does make a big difference, basically the same as conventional drivers in as much that you have to balance SPL, efficiency, bandwidth, distortion cabinet shape and volume etc.
BMR 's are are not "breakers of the laws of Physics.." they are different from the crowd but not totally different ie plasma driver or electro static.
The BMR's do have the best off axis performance I have seen / heard, its really jaw dropping at times, esp when used in a line array.
Balancing out their strengths and weakness's, I now believe they are a dream driver for on wall line source designs, esp when you can use DSP to Eq the response, provide steep linear phase crossovers and protect the drivers from bass / low midrange.
My final design is going to use 16 of the 4.5 inch drivers per speaker combined with 6 or 8 6.5 or 8 inch drivers covering the 80Hz to 320Hz band.
Two or three corner located sealed subs 12 and 15 inch will take care of the home cinema end of the deal. Should be fun...!
Cheers
Derek.

PS Seretin
You got me Overkill by name and overkill by nature!
The DEQX is a bit special as its core USP is its time and phase coherent Linear Phase fiters, 48 dB per octave up to 300 dB per octave ( yes three hundred!) and 96dB is the sweet spot for the BMR at 100Hz crossover.
Its all on the DEQX High Definition Audio website... basically it modifies group delay, phase and step response of the individual drivers and / or the on axis frequency response with its room EQ, plus individual driver ( not just speaker) time delay...Phew! It utilises both IIR and FIR filters and has good number crunching ability via twin shark DSP chips. Its latency is low enough you can use it in a high end Blu Ray home cinema with no video sync errors.
I dont use its 6 channels of built in DAC's, better to build your own, also I bypass its power supply and run mine from a good LiPo batter supply.
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Old 23rd February 2012, 08:39 PM   #37
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Rega's brand new top of the range loudspeaker uses a BMR for Midrange only.
They have used their own (modified) tweeter for the highs. Perhaps they wanted the extreme highs to be a bit more directional or a bit more showroom friendly sparkle?
These Speakers will be at the Bristol show in the UK this weekend for anyone interested in high end BMR performance. No doubt Naim Ovators will be their also.
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Old 23rd February 2012, 09:32 PM   #38
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When I said mid only I meant to imply that the speaker is a three way.
For all I know Rega may use this with an extremely high crossover frequency. Perhaps using the soft dome like a super tweeter?
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Old 23rd February 2012, 10:09 PM   #39
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Default Rega BMR

Hi Rob,

Interesting, I didnt know Rega were using a BMR driver.
The top end of the 4.5 inch BMR's is really good, cymbals sound solid and have rich decay and tone, but not as extended as a good ribbon.
I prefer the BMR but I think you could have hit the nail on the head with the " showroom sparkle"...
I would say its a bit like the Beyma TPL driver Vs the RAAL Ribbon, if you like the ultimate air and "hifi feel" go for the RAAL, if you want to recreate the amazing dynamics and tone of a cymbal go for the TPL...
The BMR top end is not as good as a TPL by the way, but its a quarter of the price and covers a the 6 main octaves beautifully, Vs the TPL's top 3.5 octaves... Now maybe combine a line array or BMR's with two or 4 TPL's per side... but thats big bucks right there, then add on the sub 300Hz band...

Cheers
Derek.
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Old 23rd February 2012, 11:01 PM   #40
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Derek,
It sounds like BMR's could be a force for good in the future. It's all about bang for buck for those of us in the real world.

Probably the Heil AMT's in Adam Audio's top speakers are the best I have heard in terms of cleanest upper treble extension.

I use the Linkwitz Pluto 2.1's with 2 inch fullrange drivers used as treble units. The treble is glorious, I wish more cone and dome speakers could sound this good.


I believe that broad even dispersion and smooth integration with the bass/mid and low distortion in the low and mid treble is far more important that ultimate frequency extension. I would probably like the BMR drivers when done well.
The harsh sound from poor crossovers and over taxed drive units (with distortion where the ear is most sensitive) can lead some audiophiles to seek out exotic treble units with the promise of incredible bat eared frequency extension capability, yet most of these guys will never be able to hear let alone reproduce such sounds even if it even exists on the recording.
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