Pano,
The on-line videos I have seen were not loud at all, what dB SPL were they played at, at what distance?
You can read my reaction to them in post #4, and what Ivan Beaver (Tom's right hand man, responsible for DSL's measurements and implementation and such) thought in post #6 here:
New speaker technology • speakers that don't feed back!
My response to the BMR is a Deja Vu of last year's DML, still no off axis response curves posted. Funny how that works
.Art
I forgot to pull out my iPhone SPL meter at the demo. But it was loud enough that you had to shout at the person next to you. You know, typical club levels.
And I did stick an SM58 mic right into the panel without it howling.
What interested me was how they might react to the room. We have a Meyer line array hung in a very difficult room here in town. It's about 200'x200' and very live. We tried to get a demo of the Tectonic array hung in there last month. So far the scheduling hasn't worked out. That would tell me right away how well they work.
I'm still interested in hearing a pair of the panels in a domestic setting. I suspect they would work very well.
But it was loud enough that you had to shout at the person next to you. You know, typical club levels.And I did stick an SM58 mic right into the panel without it howling.
What interested me was how they might react to the room. We have a Meyer line array hung in a very difficult room here in town. It's about 200'x200' and very live. We tried to get a demo of the Tectonic array hung in there last month. So far the scheduling hasn't worked out. That would tell me right away how well they work.
I'm still interested in hearing a pair of the panels in a domestic setting. I suspect they would work very well.
Measurements will be interesting!
Thanks Lynn,
I do hope some of my BMR ramblings are of interest!
Art,
You are quite right to ask for measurements and as soon as I get the production drivers I will build the test cabinets and get the measurements done...They will all be carried out by a top independent acoustic engineer.
Pano,
Thanks for posting this, the big Pro panels from Tectonic are interesting, I have not heard them but most of the early reports are positive so I am looking forward to hearing them.
I am building some large panels for live sound use, 12 BMR's high with 5 wide so 60 drivers per panel... Sd approx. 7 or 8 twelve inch drivers, but as Art correctly points out much less Vd than typical Pro drivers with +/- 10mm Xmax.
My panels are stackable and designed to crossover to subs at 80Hz.
I do not use any ribbons or extra HF drivers, top end is great without them.
Each individual driver is 89dB for 1 watt at 1 meter.
The 6 Ohm panels are approx. 102 dB for 1 watt at 1 meter and have very good power handling.
All the best
Derek.
Thanks Lynn,
I do hope some of my BMR ramblings are of interest!
Art,
You are quite right to ask for measurements and as soon as I get the production drivers I will build the test cabinets and get the measurements done...They will all be carried out by a top independent acoustic engineer.
Pano,
Thanks for posting this, the big Pro panels from Tectonic are interesting, I have not heard them but most of the early reports are positive so I am looking forward to hearing them.
I am building some large panels for live sound use, 12 BMR's high with 5 wide so 60 drivers per panel... Sd approx. 7 or 8 twelve inch drivers, but as Art correctly points out much less Vd than typical Pro drivers with +/- 10mm Xmax.
My panels are stackable and designed to crossover to subs at 80Hz.
I do not use any ribbons or extra HF drivers, top end is great without them.
Each individual driver is 89dB for 1 watt at 1 meter.
The 6 Ohm panels are approx. 102 dB for 1 watt at 1 meter and have very good power handling.
All the best
Derek.
Derek,
You will find the horizontal dispersion of 5 full range drivers placed side by side to be "interesting" (that is, terrible
). Of course, that never stopped Dr. Bose, either .Why haven't you measured your prototype drivers axial response rather than making assumptions regarding their dispersion?
What differences do you anticipate in the production drivers compared to your pre-production drivers?
Art
You will find the horizontal dispersion of 5 full range drivers placed side by side to be "interesting" (that is, terrible
Art
Art - your humor is matched only by your knowledge of the subject matter.
Thanks Earl, that makes me feel all warm and fuzzy, like listening to a Bose 802 loudspeaker.
Live sound panels
The live sound panels will indeed be interesting!
I expect my own measurements of the prototype drivers to be broadly similar to the production drivers. The main difference is I only have 4 prototypes of my own drivers....Hardly a line array or a panel, and I am not going to publish measurements of anyone else's drivers!
The panels are of course designed for high SPL's and huge coverage, the goal is to throw low distortion sound over both the wide and far field.
The key points are:
(1)The theoretical interference patterns do exist but are not audible with music only with pink noise and only in the near field under 1 meter....The panels (stackable) are designed to cover up to 64 meters distance....
(2) The huge increase in power handling and simultaneous decrease in distortion (5 times the drivers = 80% reduction in driver cone movement) vastly out weighs the inaudible interference pattern issue.
The reality is that a broad dispersion / even power response driver can be used as a multi point source as all the drivers "fill in the gaps" at different locations in 3D space....
Imagine an audience of 1,000 people in front of a stage using approx. 1,000 BMR's per side ( approx. 11 meters tall and 1 meter wide or 5.5 m by 2 m wide depending on stage), every cubic cm of air covering the audience will be pressurised (compression or rarefaction of air is the only way we hear anything) by one or more drivers and everyone will be able to hear all of the music....If you walk around with your mic and portable recorder....There are no dead spots!!
A recent domestic experiment proved fascinating....
These tests were carried out using an older version of the rubber surround BMR and a random (non audiophile) group 23 individuals (18 to 50 year's of age) all of whom were either musicians, regular cinema goers or have small home based studio set ups to mix their own music.
The test involved comparing single column arrays Vs panels in both two channel and home cinema set ups, attached a pic of the raw panels (will get some pics with drivers soon) to test the standard DTS / Dolby recommendation that the front three speakers must be identical and vertically orientated to give identical dispersion...This is how DTS etc is mastered in the studio.
I used 3 of the 9 by 3 (27 BMR's) panels, horizontally orientated but double wired, to allow all 27 drivers ( 12 Ohms) or just 3 vertical drivers ( 12 Ohms) to be played with a quick change of speaker cables.
Now in "theory" the three columns of 3 drivers should be the "best" and the 3 panels of 27 drivers each should be a sonic train crash....
Well gentle men, let me assure you not only is the theory a complete load of rubbish, but I am so blown away by the results of this test I am going to commit significant funds to duplicating the test in a more controlled environment, video the entire process and involve high profile music and press professionals.....
I am convinced that the BMR driver is perfectly suited to both large scale panel and line array applications as well as small scale domestic use as a point source plus sub or medium scale panel or line array.
As I have explained across several threads recently this is new and exciting and heading down the commercial route in 2015, but I hope to bring some fantastic DIY kits to the guys here.
All this theoretical banter with you guys is just for fun....I am hardly expecting the "old guard" with "50 years and more" invested in cones / domes crossovers and horns to welcome me with open arms!
Vested interests and a life time of "my way or the highway" have long dominated loudspeaker design and that is exactly the same here in DIY world.
I love being the cat among the pigeons and watching the feathers.....
Hope the above helps!
Cheers
Derek.
Hi Art,Derek,
You will find the horizontal dispersion of 5 full range drivers placed side by side to be "interesting" (that is, terrible
Why haven't you measured your prototype drivers axial response rather than making assumptions regarding their dispersion?
What differences do you anticipate in the production drivers compared to your pre-production drivers?
Art
The live sound panels will indeed be interesting!
I expect my own measurements of the prototype drivers to be broadly similar to the production drivers. The main difference is I only have 4 prototypes of my own drivers....Hardly a line array or a panel, and I am not going to publish measurements of anyone else's drivers!
The panels are of course designed for high SPL's and huge coverage, the goal is to throw low distortion sound over both the wide and far field.
The key points are:
(1)The theoretical interference patterns do exist but are not audible with music only with pink noise and only in the near field under 1 meter....The panels (stackable) are designed to cover up to 64 meters distance....
(2) The huge increase in power handling and simultaneous decrease in distortion (5 times the drivers = 80% reduction in driver cone movement) vastly out weighs the inaudible interference pattern issue.
The reality is that a broad dispersion / even power response driver can be used as a multi point source as all the drivers "fill in the gaps" at different locations in 3D space....
Imagine an audience of 1,000 people in front of a stage using approx. 1,000 BMR's per side ( approx. 11 meters tall and 1 meter wide or 5.5 m by 2 m wide depending on stage), every cubic cm of air covering the audience will be pressurised (compression or rarefaction of air is the only way we hear anything) by one or more drivers and everyone will be able to hear all of the music....If you walk around with your mic and portable recorder....There are no dead spots!!
A recent domestic experiment proved fascinating....
These tests were carried out using an older version of the rubber surround BMR and a random (non audiophile) group 23 individuals (18 to 50 year's of age) all of whom were either musicians, regular cinema goers or have small home based studio set ups to mix their own music.
The test involved comparing single column arrays Vs panels in both two channel and home cinema set ups, attached a pic of the raw panels (will get some pics with drivers soon) to test the standard DTS / Dolby recommendation that the front three speakers must be identical and vertically orientated to give identical dispersion...This is how DTS etc is mastered in the studio.
I used 3 of the 9 by 3 (27 BMR's) panels, horizontally orientated but double wired, to allow all 27 drivers ( 12 Ohms) or just 3 vertical drivers ( 12 Ohms) to be played with a quick change of speaker cables.
Now in "theory" the three columns of 3 drivers should be the "best" and the 3 panels of 27 drivers each should be a sonic train crash....
Well gentle men, let me assure you not only is the theory a complete load of rubbish, but I am so blown away by the results of this test I am going to commit significant funds to duplicating the test in a more controlled environment, video the entire process and involve high profile music and press professionals.....
I am convinced that the BMR driver is perfectly suited to both large scale panel and line array applications as well as small scale domestic use as a point source plus sub or medium scale panel or line array.
As I have explained across several threads recently this is new and exciting and heading down the commercial route in 2015, but I hope to bring some fantastic DIY kits to the guys here.
All this theoretical banter with you guys is just for fun....I am hardly expecting the "old guard" with "50 years and more" invested in cones / domes crossovers and horns to welcome me with open arms!
Vested interests and a life time of "my way or the highway" have long dominated loudspeaker design and that is exactly the same here in DIY world.
I love being the cat among the pigeons and watching the feathers.....
Hope the above helps!
Cheers
Derek.
Panel material
Hi Pano,
You are 100% on the money with your observation about panel material being key in the BMR.
In fact panel material and the surround / suspension are where I have spent most of my time and effort.
The compromise between mass / surface area / suspension compliance are more dominant over motor / voice coil / Xmax and chassis compared to push pull drivers where a lot of emphasis is placed on Xmax and huge motor capability.
It boils down to energy dissipation and the way the energy travels through and over the former / spider / diaphragm and surround.
The flat diaphragm sits in the middle of the "energy chain" and must accept energy ( from the VC / former) as efficiently as possible, allow it pass with minimum resistance through its self and over its surface and into the surround.
In turn, the surround of must not bounce or reflect the energy back into the diaphragm, or at least the goal is to minimise this as a top priority.
A honeycomb structure has lots of advantages over a thick single layer or multi layer construction....Ability to apply damping on three surfaces but leave the outward facing surface as light, smooth and rigid as possible...Leaving this outer surface as the "path of least resistance" is every bit as important as applying the correct damping to the inner 3 surfaces.
I am sure there is more yet to understand on this subject and one day I hope to collaborate with Robert Maicks of Sistrum Platform fame and explore more about the science behind Coulombs Friction.
Friction - Wikipedia, the free encyclopedia ....Also Bud Purvine from this forum has some interesting ideas on how energy travels across speaker diaphragms and into the surrounding materials....
Also how the diaphragm material bonds with the balancing mass's applied at the strategic nodes is important....Long term vibration at the joints mean the two materials and the glue must effectively become one.
In summary I have gone for a Nomex and paper composite honeycomb diaphragm with either a rubber or silk surround, the rubber surround is best below 150Hz or so, the silk is significantly better above 150Hz.
The resulting waterfall plot is pristine!
I have posted a pic of it somewhere on the forum recently ( 2 weeks ago ish?) , I am on my phone at the mo so cant attach it, have a look for it, its a beauty, clean as a whistle in the time domain which is ( IMO) more important than the frequency domain.
The reason is I believe this is Eq can correct frequency response dips if and only if they are the same on all axis ie a very even and broad power response which is exactly what the BMR does ( well the good ones do this!)
Anyway, as usual I am rambling on too much!
Hope some of this helps.
Cheers
Derek.
Hi Pano,
You are 100% on the money with your observation about panel material being key in the BMR.
In fact panel material and the surround / suspension are where I have spent most of my time and effort.
The compromise between mass / surface area / suspension compliance are more dominant over motor / voice coil / Xmax and chassis compared to push pull drivers where a lot of emphasis is placed on Xmax and huge motor capability.
It boils down to energy dissipation and the way the energy travels through and over the former / spider / diaphragm and surround.
The flat diaphragm sits in the middle of the "energy chain" and must accept energy ( from the VC / former) as efficiently as possible, allow it pass with minimum resistance through its self and over its surface and into the surround.
In turn, the surround of must not bounce or reflect the energy back into the diaphragm, or at least the goal is to minimise this as a top priority.
A honeycomb structure has lots of advantages over a thick single layer or multi layer construction....Ability to apply damping on three surfaces but leave the outward facing surface as light, smooth and rigid as possible...Leaving this outer surface as the "path of least resistance" is every bit as important as applying the correct damping to the inner 3 surfaces.
I am sure there is more yet to understand on this subject and one day I hope to collaborate with Robert Maicks of Sistrum Platform fame and explore more about the science behind Coulombs Friction.
Friction - Wikipedia, the free encyclopedia ....Also Bud Purvine from this forum has some interesting ideas on how energy travels across speaker diaphragms and into the surrounding materials....
Also how the diaphragm material bonds with the balancing mass's applied at the strategic nodes is important....Long term vibration at the joints mean the two materials and the glue must effectively become one.
In summary I have gone for a Nomex and paper composite honeycomb diaphragm with either a rubber or silk surround, the rubber surround is best below 150Hz or so, the silk is significantly better above 150Hz.
The resulting waterfall plot is pristine!
I have posted a pic of it somewhere on the forum recently ( 2 weeks ago ish?) , I am on my phone at the mo so cant attach it, have a look for it, its a beauty, clean as a whistle in the time domain which is ( IMO) more important than the frequency domain.
The reason is I believe this is Eq can correct frequency response dips if and only if they are the same on all axis ie a very even and broad power response which is exactly what the BMR does ( well the good ones do this!)
Anyway, as usual I am rambling on too much!
Hope some of this helps.
Cheers
Derek.
Derek,
1) Obviously, the popularity of systems like the Bose 901 and 902 prove that many people are not bothered by interference patterns. Those of us that do find the interference patterns of full range side by side arrays both audible, and objectionable, disagree with your assessment of them.
Of course, if you can't hear them yourself, the interference patterns only exist as a measured reality you can choose to ignore in a domestic environment.
2) You present a circular argument, choosing a driver that requires multiples to have a low level of distortion at a reasonable SPL and sensitivity, then claim that the problems multiple arrayed drivers arrival times create is inaudible. There is a vast difference between "no dead spots" and consistent sound over a specified coverage pattern.
3) In your "fascinating domestic experiment" you make no mention that the surrounding un-powered drivers act as passive radiators, altering the response of the lesser quantity of drivers used, making their response even more ragged than the multiple driver response.
Many studies have shown that "smoothness counts" to listeners, so even on that basis alone the 27 would be preferred over the 9, and when you also consider that three times the cone area results in around 5 dB more SPL, and people also often equate louder as better, your "fascinating domestic experiment" simply points out that you are "easily blown away"
.Not that we can't all suffer from sonic hallucinations, several years back I purchased a pair of Renkus Heinz ICX7 mini line arrays after hearing them demoed in a large room with a Nora Jones CD playing through them, an artist I had not heard before. Later, I realized that in spite of a complex shading crossover scheme on the 7 tweeters (to avoid comb filtering), a simple column of eight 4 inch five watt fifty cent full range NSB (No Stinking Badges) buyout speakers had more dynamic range, better overall sound above 100 Hz, and cost a small fraction of what I paid for the ICX7
. I now make sure I always listen and measure before purchase, took me quite some time to sell off the ICX7s, but I still enjoy the Nora Jones tunes I purchased after the demo..
Art
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Discovering Nora!
Oh Art, how could you....? Sell off the pair of loudspeakers that you discovered Nora on....You marble hearted fiend!!
Re your other points....
It goes without saying we used an SPL meter to equalise the volume at the listening position ....I didn't think I would have to point out such basics to one such as yourself...
I am not a fan of Bose so I must agree with you.
Feeling naughty are we Art? Putting words in my mouth, or did you just get it wrong? My quote :
"The theoretical interference patterns do exist but are not audible with music only with pink noise and only in the near field under 1 meter....The panels (stackable) are designed to cover up to 64 meters distance...."
Let me spell it out slowly for you....."The interference is audible with pink noise under 1 meter".... Now if you are still not getting it you are beyond my help!
I clearly state " Neither I or any of the group could detect any interference patterns with music" so guess what, we chose to ignore them...We agree again!
Also your maths is wrong again, (or was that in another thread where you posted the wrong dB increase when doubling up Sd)?...
This experiment used 3 panels each with 27 drivers....So that's 81 drivers when all connected, Vs 9 ( each one of the 3 panels only using 3 drivers)....
The rest of your point 3 does not warrant a serious reply so keeping it light hearted how about a word puzzle ( you appear to need some practice here...
"Straws, clutching at" ...Enjoy!
Your other "point" about a circular argument and or how I like / have chosen a driver which needs to be used in multiples....Again utter rubbish, I have never stated or implied this....My own version has greater SPL with lower distortion than any of the CSS or Naim BMR's....These are already very good drivers, but hardly up to live sound duty!
That's about it for now...Off to pour some Red and chill with our mutual friend Nora....There you go Art, we are really have so much in common!
Cheers
Derek.
Oh Art, how could you....? Sell off the pair of loudspeakers that you discovered Nora on....You marble hearted fiend!!
Re your other points....
It goes without saying we used an SPL meter to equalise the volume at the listening position ....I didn't think I would have to point out such basics to one such as yourself...
I am not a fan of Bose so I must agree with you.
Feeling naughty are we Art? Putting words in my mouth, or did you just get it wrong? My quote :
"The theoretical interference patterns do exist but are not audible with music only with pink noise and only in the near field under 1 meter....The panels (stackable) are designed to cover up to 64 meters distance...."
Let me spell it out slowly for you....."The interference is audible with pink noise under 1 meter".... Now if you are still not getting it you are beyond my help!
I clearly state " Neither I or any of the group could detect any interference patterns with music" so guess what, we chose to ignore them...We agree again!
Also your maths is wrong again, (or was that in another thread where you posted the wrong dB increase when doubling up Sd)?...
This experiment used 3 panels each with 27 drivers....So that's 81 drivers when all connected, Vs 9 ( each one of the 3 panels only using 3 drivers)....
The rest of your point 3 does not warrant a serious reply so keeping it light hearted how about a word puzzle ( you appear to need some practice here...
"Straws, clutching at" ...Enjoy!
Your other "point" about a circular argument and or how I like / have chosen a driver which needs to be used in multiples....Again utter rubbish, I have never stated or implied this....My own version has greater SPL with lower distortion than any of the CSS or Naim BMR's....These are already very good drivers, but hardly up to live sound duty!
That's about it for now...Off to pour some Red and chill with our mutual friend Nora....There you go Art, we are really have so much in common!
Cheers
Derek.
Derek,1)It goes without saying we used an SPL meter to equalise the volume at the listening position ....I didn't think I would have to point out such basics to one such as yourself...
2)Let me spell it out slowly for you....."The interference is audible with pink noise under 1 meter".... Now if you are still not getting it you are beyond my help!
I clearly state " Neither I or any of the group could detect any interference patterns with music" so guess what, we chose to ignore them...We agree again!
3)Also your maths is wrong again, ...This experiment used 3 panels each with 27 drivers....So that's 81 drivers when all connected, Vs 9 ( each one of the 3 panels only using 3 drivers)....
4)Your other "point" about a circular argument and or how I like / have chosen a driver which needs to be used in multiples....Again utter rubbish, I have never stated or implied this...
1) I'm not a mind reader, so when you mentioned a double wire test to allow all 27 drivers ( 12 Ohms) or just 3 vertical drivers ( 12 Ohms) to be played with a quick change of speaker cables, I didn't guess that you used also used a SPL meter to "equalise the volume at the listening position". You also stated no other relevant details, such as the distance of the listening position to the three arrays, or size and shape of the listening venue, etc.. Did you also happen to equalize the frequency response so the response would be somewhat similar at the LP, or assume that 9 times the drivers would result in the same response at all frequencies and a similar dispersion pattern?
2) I hear interference patterns and changes in frequency response with music or pink noise when moving my head from side to side when listening to a system composed of multiple horizontally positioned full range drivers, or even two way systems with drivers placed horizontally, but you don't need to spell it out slowly again that you and your group didn't, I got that the first time, thanks
.3) You are correct, I mistakenly figured you had tripled, rather than gone to 9 times the driver count for comparison. The sensitivity difference from 9 to 81 drivers should be a bit over +9 dB if they were summing coherently, which can only occur in the far field, which would be quite some distance for a 27 wide array of drivers. How many dB did you turn the 81 drivers down by?
4) Comparing 81 drivers to 9 drivers implies to me that 9 are not up to the task, whether you happen to like or have chosen the drivers for whatever reasons.
Cheers,
Art
Panel = summing of vertical and horizontal arrays?
Hi Art,
You are quite right, I didn't give enough info about the test, to be honest I wasn't going to even mention this test, I was going to wait until the controlled test was documented ....I am finding it hard to contain my enthusiasm!
Re the volume, it was reduced / increased on an AV receiver with a digital readout, by 8dB as a start, then we used an SPL meter at the listening position with pink noise to match within 1dB, we ended up with a 9dB reduction / increase swapping down / up from the 81 drivers to the 9.
Your point 2 is interesting and got me thinking more about the differences / benefits between vertical / horizontal and panel arrays....
ie panels are just a combination of vertical and horizontal arrays, how they sum in rooms appears (sounds) to be better than either the short arrays ( really more point source) or medium length, 1,100mm wide sound base below a TV, arrays.
I will investigate this more once I get all my demo speakers built up, but at this early stage one thing is clear:
There are a huge number direct and reflected sources involved in room with panels, yet the sonic image remains stable regardless of standing / sitting / walking about....This aspect is what I want be able to demonstrate on the video....A picture paints a thousand words and the audience's faces are classic!
They were not asked to comment during the music / movie clips, but asked to make their own notes if they wanted to and then give opinions afterwards.
They had no idea what speakers or how many drivers were playing at any point, They were just asked to give their opinion of the quality of the clips in a random order. The more techy orientated guys asked some probing questions on what we were doing but we gave nothing away....Enjoy the coffee and the music, that's it!
Just to put some perspective on the single BMR driver used as point source, not in a line array or panel....
The attached single BMR is crossed over ( via a low cost AV amp) at 160Hz to a pair of 6.5 inch bass drivers, active amplification via Musical Fidelity on the BMR and Audiolab on the bass.
The speakers fill a medium room (8m long 5m wide) with a powerful and natural sound, easily hitting 97dB music peaks at the 5m listening position. This is equivalent to 108dB at 1 meter...Not to shabby for a 4.5 inch full ranger!
Hope this helps
Cheers
Derek.
Hi Art,
You are quite right, I didn't give enough info about the test, to be honest I wasn't going to even mention this test, I was going to wait until the controlled test was documented ....I am finding it hard to contain my enthusiasm!
Re the volume, it was reduced / increased on an AV receiver with a digital readout, by 8dB as a start, then we used an SPL meter at the listening position with pink noise to match within 1dB, we ended up with a 9dB reduction / increase swapping down / up from the 81 drivers to the 9.
Your point 2 is interesting and got me thinking more about the differences / benefits between vertical / horizontal and panel arrays....
ie panels are just a combination of vertical and horizontal arrays, how they sum in rooms appears (sounds) to be better than either the short arrays ( really more point source) or medium length, 1,100mm wide sound base below a TV, arrays.
I will investigate this more once I get all my demo speakers built up, but at this early stage one thing is clear:
There are a huge number direct and reflected sources involved in room with panels, yet the sonic image remains stable regardless of standing / sitting / walking about....This aspect is what I want be able to demonstrate on the video....A picture paints a thousand words and the audience's faces are classic!
They were not asked to comment during the music / movie clips, but asked to make their own notes if they wanted to and then give opinions afterwards.
They had no idea what speakers or how many drivers were playing at any point, They were just asked to give their opinion of the quality of the clips in a random order. The more techy orientated guys asked some probing questions on what we were doing but we gave nothing away....Enjoy the coffee and the music, that's it!
Just to put some perspective on the single BMR driver used as point source, not in a line array or panel....
The attached single BMR is crossed over ( via a low cost AV amp) at 160Hz to a pair of 6.5 inch bass drivers, active amplification via Musical Fidelity on the BMR and Audiolab on the bass.
The speakers fill a medium room (8m long 5m wide) with a powerful and natural sound, easily hitting 97dB music peaks at the 5m listening position. This is equivalent to 108dB at 1 meter...Not to shabby for a 4.5 inch full ranger!
Hope this helps
Cheers
Derek.
Attachments
Derek,
Having gone through the excitement of "discovering" and building speaker designs over the last 44 years, I can relate to your enthusiasm. Each "new" design's flaws always somehow seem to be overcome by some perceived sonic advantage.
To put some perspective on the "single BMR driver" again requires interpolation of your limited description.
1) You say "The speakers fill a medium room" implying a pair of speakers, each using a pair of 6.5" bass drivers and a BMR, all six drivers contributing to the SPL level, with the bass drivers likely some unknown amount louder than the BMR. Assuming the pair of BMR alone can achieve 97dB music peaks at 5m (unknown, though if you specified dBA scale, it would be known) we must subtract 6 dB since it takes two drivers to achieve 97 dB, so the level required for each driver now drops to a bit below 103 dB per driver assuming a six dB drop per doubling of distance, as would occur in free space, outdoors.
2) Indoors, sound does not drop at 6 dB per doubling of distance, the reduction in level is dependent on the reverberant field. An acoustically "live" room may show virtually no change in SPL as measured on a dB meter from 1m in front of the speaker to the back of the room.
As an example, in my listening room of 6.1m x 3.3m x 2.15m containing no acoustical treatment other than a sofa, some chairs and bar stools, I just measured myself singing a "room filling" continuous note at 100 dBC at 5 meters, then taking the meter outdoors, my singing level at that distance was only 90 dB, sounding only half as loud to anyone that would care to listen.
3) Having used Galaxy Hot Spot monitors over the years, I have verified the 5" "full range" driver they use is about 90 dB 1w1m above 160 Hz, at 100 watt peaks it can do around 110 dB. Depending on your room reverberation level, the Hot Spot driver is capable of somewhere in the range of 7 to 17 dB more output than your BMR.
Like you say, not too shabby for a 5" full ranger
.Art
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dB drag racing...Aint what it used to be!
Hey Art,
You really are struggling here mate...!
Comparing a HS7 that to a BMR...
Just for the avoidance of doubt, first of all I will correct your maths ( again!)
Your quote :
" Assuming the pair of BMR alone can achieve 97dB music peaks at 5m (unknown, though if you specified dBA scale, it would be known) we must subtract 6 dB since it takes two drivers to achieve 97 dB..."
Wrong! You add or subtract 3 dB for each doubling or halving of the Sd (number of drivers in this case)
Leaving your maths aside, it goes without saying that a "mega phone" ferro fluid cooled public address driver which is what the Hot spot driver is, will always go way louder than any high quality driver, if dB drag race is your criteria for audio that explains why we differ in our opinions....
Also begs the rather obvious question, if they were so amazing why don't you still use them...?
For the record :The latest spec Hot spot monitor quotes...
"126 dB at 0.5 meters from two drivers....that's 123dB (yes it is!) from 1 driver at 0.5 meters.
Now move to one meter and you drop to 117dB (there is your 6dB point source drop when you double the listening distance)
Move to 2m and you drop another 6dB to 111 dB
Move to 4m and you drop another 6dB to 105 dB
Move to 5m and you drop approx. 1.5dB to 103.5 ( based on 25% of 6dB)
Now factor in the crest ( peak SPL over continuous ) factor which should by 6dB ( AES recommend 6dB but many budget monitors quote 9dB or 10dB) and you come down to 97.5dB....Not to shabby, eh Art!!!!
Your quote :
" Having used Galaxy Hot Spot monitors over the years, I have verified the 5" "full range" driver they use is about 90 dB 1w1m above 160 Hz, at 100 watt peaks it can do around 110 dB. "
What a coincidence...My BMR that you are trying so hard to discredit for no apparent reason (or perhaps because of the maths thing on the other thread)
is 89 dB sensitive with 1 watt at one meter...So lets run the correct figures...
1 watt = 89dB
2 watt = 92dB
4 watt = 95dB
8 watt = 98dB
16 watt = 101
32 watt = 103 (Approx max continuous power handling is 32 watts per driver)
64 watt = 106dB ( assume a very conservative crest factor of 3dB)
100 watt = 107.8 dB ( based on 56% of 3dB)
128 watt = 109dB ( Possible assuming a recommended crest factor of 6dB)
So once again Art ...Not to shabby!
Off to chill with Maria Callas, Buddy Holly, James Morrison, George Benson, John ( Cougar) Mellencamp ( Lonesome Jubilee is an amazing album) and friends....Play list shuffle on JRiver is fab!
![sweet6[1].jpg](/community/data/attachments/407/407350-1cfc41f1ddd0da6042d1cdc41bc640ab.jpg)
![100_2084[1].jpg](/community/data/attachments/407/407357-ddfb6672f19f119b81f82246e8030202.jpg)
Hi Derek,
If those panels work that well, maybe you should consider building an updated version of the sweet sixteen.
A problem with those and other multiple source arrays is that for a single impulse fed into the system, what arrives at ones ears is an impulse from each source separated in time according to the differences in path length from each source to ones ears. DSP can correct that in one location but always at the expense of all other locations.
Well I did put the smiley there for a reason...
Here's a quote from the thread the picture was in:
Source thread
Here's a quote from the thread the picture was in:
Source thread
Be there done that, except that I am at something like 50 years
I was once asked by a guy to evaluate his "revolutionary new D/A convertor". It sounded god-awful and I commented on some of its flaws. He just said "But that's not the problem I am trying to fix!" - Oh OK, I missed that part.
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