Ratio of time delay to distance
Hi Tom,
Thanks for your comments, I am always delighted to hear your thoughts....I am a tiny bit in awe of your audio business achievements ....Wow springs to mind!
I have a couple of questions re your point about the time delay from the different drivers in panels:
First please bear with me on the assumption ( ignore Art!) that the BMR is a high quality full range driver (80Hz to 15Khz) with broad and even power response:
Also a couple of caveats:
For domestic use the single column arrays are more than enough.
Its only when SPL's need to reach the live sound levels are panels required, here listening distances will be much greater 5m to 50m approx.
I am assuming that the ratio of driver spacing / delay to listening distance is crucial....To use an extreme example:
If listening to a 1m square panel with 81 drivers ( 9 by 9 drivers each with 112mm square chassis mounted edge to edge) and your head was dead centre and one was listening at just 50cm, the distance from the furthest driver to the nearest driver is approx. 40% greater ( 50cm Vs 70.7cm)....
Now assume the same panel at a listening distance of 10 meters and the difference is 0.0001% ( 10 meters Vs 10meters plus 1 cm!)....Negligible ??
Also:
(1) Is there any difference between the driver to driver time delay present in a vertical line array ( floor to ceiling ) and a the same floor to ceiling vertical panel array of say 5 drivers wide? Apart from the above time delay?
I ask this because the present floor to ceiling line arrays sound stunning and obviously has a slight driver to driver time delay at the 4meters listening position.
Thanks so much in advance
Derek.
Hi Tom,
Thanks for your comments, I am always delighted to hear your thoughts....I am a tiny bit in awe of your audio business achievements ....Wow springs to mind!
I have a couple of questions re your point about the time delay from the different drivers in panels:
First please bear with me on the assumption ( ignore Art!) that the BMR is a high quality full range driver (80Hz to 15Khz) with broad and even power response:
Also a couple of caveats:
For domestic use the single column arrays are more than enough.
Its only when SPL's need to reach the live sound levels are panels required, here listening distances will be much greater 5m to 50m approx.
I am assuming that the ratio of driver spacing / delay to listening distance is crucial....To use an extreme example:
If listening to a 1m square panel with 81 drivers ( 9 by 9 drivers each with 112mm square chassis mounted edge to edge) and your head was dead centre and one was listening at just 50cm, the distance from the furthest driver to the nearest driver is approx. 40% greater ( 50cm Vs 70.7cm)....
Now assume the same panel at a listening distance of 10 meters and the difference is 0.0001% ( 10 meters Vs 10meters plus 1 cm!)....Negligible ??
Also:
(1) Is there any difference between the driver to driver time delay present in a vertical line array ( floor to ceiling ) and a the same floor to ceiling vertical panel array of say 5 drivers wide? Apart from the above time delay?
I ask this because the present floor to ceiling line arrays sound stunning and obviously has a slight driver to driver time delay at the 4meters listening position.
Thanks so much in advance
Derek.
Domestic line array example
Hi again Tom,
Sorry, I forgot to add the figures for my current single column line array:
Array height 1.82m.
Listening distance 4m to dead centre of line array.
Distance to furthest driver (very top driver) 4.123m.
% difference = 3.1% ....Negligible?
Certainly its not audible with music at the listening position, even at 1.5 m with music its not detectable.
But it is audible with pink noise at very close range, under about 1m its apparent and at 50cm its easily noticeable.
Thanks again
Derek.
Hi again Tom,
Sorry, I forgot to add the figures for my current single column line array:
Array height 1.82m.
Listening distance 4m to dead centre of line array.
Distance to furthest driver (very top driver) 4.123m.
% difference = 3.1% ....Negligible?
Certainly its not audible with music at the listening position, even at 1.5 m with music its not detectable.
But it is audible with pink noise at very close range, under about 1m its apparent and at 50cm its easily noticeable.
Thanks again
Derek.
3dB or 6dB drop when removing one driver?
Sorry Art, you are not correct.
You only subtract 3dB when removing one driver...I think where you are going wrong is assuming there is a change in impedance, there is not.
Please remember we are talking about two separate channels ( left and right) each one remains at 4 Ohms regardless of whether or not the other channel is on / off in circuit or out of circuit. There is no doubling of power, the power remains the same into each channel or the one channel when the other is switched off.
Hope we are now on the same wavelength....Pun intended!
Re in room gain / SPL reduction Vs outside / anechoic measurements....
My figures comparing the Hot Spot and BMR are both assuming anechoic measurements....So they are accurate and valid and a true comparison....
Your comparisons have not been like for like or accurate.
All the best
Derek.
Sorry Art, you are not correct.
You only subtract 3dB when removing one driver...I think where you are going wrong is assuming there is a change in impedance, there is not.
Please remember we are talking about two separate channels ( left and right) each one remains at 4 Ohms regardless of whether or not the other channel is on / off in circuit or out of circuit. There is no doubling of power, the power remains the same into each channel or the one channel when the other is switched off.
Hope we are now on the same wavelength....Pun intended!
Re in room gain / SPL reduction Vs outside / anechoic measurements....
My figures comparing the Hot Spot and BMR are both assuming anechoic measurements....So they are accurate and valid and a true comparison....
Your comparisons have not been like for like or accurate.
All the best
Derek.
If one channel is putting out one watt, the second adds another watt, 1+1=2.
Two drivers, each receiving the same voltage, result in a +6 dB gain over a single driver, + 3 dB from doubling radiated surface, +3 dB from doubling power, assuming they are mutually coupling at the measurement location.
As far as a 9x9 112mm driver array, on axis at 10 meters there is virtually no interference since the path lengths are nearly the same, but measure the path length difference at any off axis point and you can determine the cancellation frequencies that will occur.
A vertical line array maintains the same horizontal coverage as a single unit, and reduces vertical beam width, both potentially good at the listening position from left to right, but still a problem up and down. Using 5 wide, horizontal problems occur for the same path length difference already mentioned above, and as Tom Danley previously mentioned:
"A problem with .... 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."
Art
dB drop Sd and power
Thanks for your dB / Sd explanation Art,
I agree 1 =1 =2 !
I think I now understand your point....
You are reducing in room SPL by 6dB because you are halving the total power (but maintaining the same impedance) in addition to halving the Sd.
That makes sense and is correct in theory.
But the reason the SPL meter only drops by 3dB when you mute one channel is that unless you are in the exact centre, the two drivers (left & right channel) will not sum perfectly.
Stand close to one channel the other has little or no effect on SPL.
Also thanks for your comments on the vertical array /panel questions, I am hoping Tom comes back with more on this.
All the best
Derek.
Thanks for your dB / Sd explanation Art,
I agree 1 =1 =2 !
I think I now understand your point....
You are reducing in room SPL by 6dB because you are halving the total power (but maintaining the same impedance) in addition to halving the Sd.
That makes sense and is correct in theory.
But the reason the SPL meter only drops by 3dB when you mute one channel is that unless you are in the exact centre, the two drivers (left & right channel) will not sum perfectly.
Stand close to one channel the other has little or no effect on SPL.
Also thanks for your comments on the vertical array /panel questions, I am hoping Tom comes back with more on this.
All the best
Derek.
ROTFL
In ECM/RADAR this is known as burn through. It is the relative distance vs power. If your plane has 5kw to jam the ground based site, the power level it has could easily be 5 million watts. The point where they become equal is dead mans land. The same is true inversely, if the average room level at listening position is say 90dB @ 4m and you move =>1 meter in either direction closer that is more than enough to upset the added acoustical gain afforded by the farther speaker.
Derek,
Indoors, the reverberant field makes nonsense of any summation and/or inverse square laws. 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, and muting one speaker, as you note, may only drop level 3 dB, more or less, since room summation is not complete due to random reflections causing interference patterns.
Because of all that, I had/have little confidence in your BMR sensitivity estimates with your in room simple dB meter readings.
Take the speakers outdoors, well away from boundaries, post the measured axial one meter sensitivity at "X" voltage and we can start communicating with known quantities that are repeatable- room measurements are not, unless two rooms happen to be identical.
Art
Full suite of independant measurements ...
Hi Art,
No worries, I can understand your scepticism and once the production drivers arrive I will commission the professional independent measurements.
Its important that I only publish 100% independently verified measurements as I am serious about the long term commercial side to these drivers.
I would happily publish my indoor graphs with a caveat if I was only planning on selling drivers, DIY kits and speakers direct to the public, but that is a small niche market and not my main focus.
You can imagine the problems it would cause a year from now if my pre production indoor measurements were used by my soon to be commercial competitors ....The web is a small place!
I hope you understand and don't mind being patient.
If I were to guess at the final out door or anechoic sensitivity measured with top grade gear, I would still say above 87dB for 1 watt at 1 meter....Should know for a fact round Christmas.
Cheers
Derek.
Hi Art,
No worries, I can understand your scepticism and once the production drivers arrive I will commission the professional independent measurements.
Its important that I only publish 100% independently verified measurements as I am serious about the long term commercial side to these drivers.
I would happily publish my indoor graphs with a caveat if I was only planning on selling drivers, DIY kits and speakers direct to the public, but that is a small niche market and not my main focus.
You can imagine the problems it would cause a year from now if my pre production indoor measurements were used by my soon to be commercial competitors ....The web is a small place!
I hope you understand and don't mind being patient.
If I were to guess at the final out door or anechoic sensitivity measured with top grade gear, I would still say above 87dB for 1 watt at 1 meter....Should know for a fact round Christmas.
Cheers
Derek.
Derek,
Based on measured response of the Tectonic and other BMR, other than at the upper HF peaks evident in their published response, it appears your sensitivity "guess" may be about 6 dB high. Of course, a simple dB meter test would read those peaks as very close to your guess.
If I were planning a release of a commercial product, I might commission professional independent measurements after I had already conducted my own. Why you would not conduct measurements on prototypes prior to commissioning more product is beyond me.
So I don't really understand, and am not feeling particularly patient with you promoting your future products with unfounded claims and guesses, rather than measurements that would back up their merit. Well actually, the skeptic in me thinks you don't share measurements because either they look bad (the reason you don't see polar response measurements for any panel based systems) or you simply have not bothered to make them.
In either case, please excuse my skepticism until you share some actual useful data, and don't expect me to hold my breath during the interim
.Cheers,
Art
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Old school closed mind or vested interest...?
Derek,
"Based on measured response of the Tectonic and other BMR, ....."
My BMR is not like any of them....!
" If I were planning a release of a commercial product, I might commission professional independent measurements after I had already conducted my own....."
Art, for the 10th time on this thread and others....Of course I have my done own (indoor) measurements and of course I am greatly encouraged by them, now after 4 years, not so good on Mk 1 versions at the start!
Are you trying to put the readers of this thread to sleep by asking the same basic questions and ignoring the answers I keep having to repeat ....Even I am getting bored!
Here I will just cut n paste from my previous post...
" Its important that I only publish 100% independently verified measurements as I am serious about the long term commercial side to these drivers.
I would happily publish my indoor graphs with a caveat if I was only planning on selling drivers, DIY kits and speakers direct to the public, but that is a small niche market and not my main focus.
You can imagine the problems it would cause a year from now if my pre production indoor measurements were used by my soon to be commercial competitors ....The web is a small place!"
Art quote :"So I don't really understand...."
That's abundantly clear to all...!!!
Art quote : "and am not feeling particularly patient"
OMG well please forgive me, I am so deeply sorry for wasting your Artfullness precious time.....I must have missed the part where I forced you to engage with me.....
Is it ok with you if I continue to post....Maybe I should be banned for wasting your time by even trying to introduce some new ideas and drivers....
With hind sight how could I be so stupid, to even dare to think I might even one day offer drivers or kits to other members.....Of course I was forgetting that no one on this forum would ever want to try anything new upon which the Artmaster had not seen fit to bestow his blessing....
Art quote : " with you promoting your future products with unfounded claims and guesses...."
Oh really....Apart from my own intense work over the last 4 years, there have been 4 very senior electronic engineers and specialist driver designers from both the Danish and Chinese offices of Tymphany working on this driver ....
My project is being treated very seriously by them....
I am looking at their data....Their measurements....If you had bothered to check the waterfall plot I published a few weeks ago was a Tymphany measurement....
Today I have a 4 page " Sample Submission Report" on my desk , here are a few Tymphany TS data measurements on the double roll silk surround version.....Without revealing anything of a commercially sensitive nature and only for the other more open minded forum members....
Revc - 3.4Ohm
Zmin - 4.97 Ohm
VC inductance - 0.02 mH
Fs - 126HzQms - 2.15
Qts 0.53
Mms 6.03g
Bl 4.82
Mms : Bl ratio 1.25
Sd 70.88
Sensitivity @ 1w/1m = 88.23 dB
Half space sensitivity @2.83 volts 90.3 dB
Art quote: "....don't expect me to hold my breath during the interim
Well, frankly my dear Art, I don't give a damn.....But if you did it would sure help reduce Global Warming...
Interesting ...
Thanks for posting Greebster, this is helpful.
I am looking into the levels at which path length differences become audible with music, audible with test tones and measurable.
Trying to separate and prioritise the most important measurements is the goal.
Cheers
Derek.
Thanks for posting Greebster, this is helpful.
I am looking into the levels at which path length differences become audible with music, audible with test tones and measurable.
Trying to separate and prioritise the most important measurements is the goal.
Cheers
Derek.
Art - why complicate things with (ugh!) measurements. We all know that true sound quality cannot be measured so why foul up the discussion with such inconsequential issues.
I have heard Overkill's rubber surround drivers in a wall mounted line array and SQ is very good by any reasonable standard. The development of these drivers is based on measurements and specifications, not snake oil and the directivity is not the same as conventional full range drivers. Skepticism is a healthy thing, but some of you guys are starting to embarrass yourselves by descending into sneering condescension. Whatever they show, I'm sure you'll find that measurements will be released when they've been performed to a good standard on actual arrays. Plenty of time to carp, if appropriate, once they are done and released. No need to hold your breath either...
Hearing is believing...!
Thanks guys!
There as so few good BMR's around very few people have actually had a chance to hear them....
I think its very encouraging that the few who have heard them react positively.
There is much to learn life and out tiny little backwater of audio is no exception, and our fragment of that tiny backwater is driver design....
My I humbly (for a change!) suggest that the BMR is worthy of a fair hearing and not to be dismissed out of hand at this early stage?
Patrick, very accurate observation....Like any 4.5 inch driver with an 88dB sensitivity its never going to go as loud as large Pro driver.
Fine in singles for most domestic / office / commercial applications but to satisfy the high SPL market, line arrays and or panels are the way to go.
Just trying to figure out the best way to do this.
All the best
Derek.
Thanks guys!
There as so few good BMR's around very few people have actually had a chance to hear them....
I think its very encouraging that the few who have heard them react positively.
There is much to learn life and out tiny little backwater of audio is no exception, and our fragment of that tiny backwater is driver design....
My I humbly (for a change!) suggest that the BMR is worthy of a fair hearing and not to be dismissed out of hand at this early stage?
Patrick, very accurate observation....Like any 4.5 inch driver with an 88dB sensitivity its never going to go as loud as large Pro driver.
Fine in singles for most domestic / office / commercial applications but to satisfy the high SPL market, line arrays and or panels are the way to go.
Just trying to figure out the best way to do this.
All the best
Derek.
This is agreed by many of us with good systems. If one is not a suck it and seer, then perhaps one will never discover ones most preferred sound.
I wrote a lot more, but then scrubbed it , as it has so often been said before.
Yes, my apologies for that, but quite simply, shouldn't measurements come first, followed by claims of superiority, rather than the other way around? Subjective claims of nirvana are just so commonplace that they don't mean anything anymore. Why even bother?
Chicken and egg....
Earl, all valid questions, hopefully Toaster wont mind if I try and answer them.
It goes without saying that all subjective development is guided by objective measurements to some degree, I doubt anyone uses one method to the total exclusion of the other.
If you had to pick one or the other, which would you choose...?
In a commercial world would you present a loudspeaker design with to the board or if it was your own money, deliver the speakers to your dealers without ever having listened to them.....Could a totally deaf person with great technical skills design a great loudspeaker without any subjective input ( his own or a listening panels) ???
Another way of looking at it....Would your typical music / movie lover rather have a great sounding speaker that did measure very well, or a loudspeaker that had great measurements but did not sound good?
The bottom line is how it sounds is more important than how it measures!
The ironic twist in the tail is that in order to be able to design the best sounding loudspeakers on needs to be guided by objective tests and measurements....
But one should never discount a design that sounds superior to, but does not t measure as well, as an inferior sounding design....
You are then being misguided by the wrong measurements... Not guided by the correct measurements!
Hope this helps
Cheers
Derek.
Earl, all valid questions, hopefully Toaster wont mind if I try and answer them.
It goes without saying that all subjective development is guided by objective measurements to some degree, I doubt anyone uses one method to the total exclusion of the other.
If you had to pick one or the other, which would you choose...?
In a commercial world would you present a loudspeaker design with to the board or if it was your own money, deliver the speakers to your dealers without ever having listened to them.....Could a totally deaf person with great technical skills design a great loudspeaker without any subjective input ( his own or a listening panels) ???
Another way of looking at it....Would your typical music / movie lover rather have a great sounding speaker that did measure very well, or a loudspeaker that had great measurements but did not sound good?
The bottom line is how it sounds is more important than how it measures!
The ironic twist in the tail is that in order to be able to design the best sounding loudspeakers on needs to be guided by objective tests and measurements....
But one should never discount a design that sounds superior to, but does not t measure as well, as an inferior sounding design....
You are then being misguided by the wrong measurements... Not guided by the correct measurements!
Hope this helps
Cheers
Derek.
Derek - of course I don't agree with you, if you know me then that should have gone without saying.
To me if measurements and someone's personal subjective impression doesn't agree then my money will be on the measurements every time. I have done far too much psychoacoustic testing to ever believe otherwise. Humans are highly flawed judges of almost anything.
To me if measurements and someone's personal subjective impression doesn't agree then my money will be on the measurements every time. I have done far too much psychoacoustic testing to ever believe otherwise. Humans are highly flawed judges of almost anything.