Description of the method:
http://home.mit.bme.hu/~daboczi/papers/multiopt.pdf
home.mit.bme.hu/~daboczi/papers/multiopt.pdf
http://home.mit.bme.hu/~daboczi/papers/multiopt.pdf
home.mit.bme.hu/~daboczi/papers/multiopt.pdf
Well when you started about those low value feedback resistors and the need for current to drive them, I had the fleeting impression something new&intersting was coming up, but then I realised this particular horse has already been beat to a horrible death by the likes of Joachim Gerhard, even in Linear Audio IIRC.
So I can't imagine John is working on a problem that has been solved - I mean you can only fool some of the people for a limited time.
Then again, with competent marketing, you can sell anything as a breakthrough, even 100 years old technology.
Is that what I was supposed to pick up Ed?
Jan
We bear some similarities
. With me it is: around 3 folks or more each year listen to one of my sound systems.Now I know whom I have to blame.
x dB/1W/1m used to be a true indicator of conversion efficiency, independent from speaker's impedance.
It was an understandable and exact spec, good for professionals and general public alike.
y dB/2.83V/1m is a sensitivity indicator. It is an exact spec for professionals who know that it is linked to a specific impedance but a confusing and miss-useable spec for general public.
Comparing sensitivity specs from brochures without looking at the speakers impedances, can be totally misleading.
Yes. And this is why I have some reservations with the case you describe:
As Richard noted, this can be frequently the case with music.
IMO picking up single details in the presence of broadband noise or broadband complex signal, has less to do with the well understood (by the experts) critical bands and more to do with the “Cocktail party effect’ which involves unstable parameters, a most difficult case for extracting generally applied conclusions.
George
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Sorry, you probably do not understand that a chopped lightning impulse is a single shot signal. Non repetititive and not my fault you do not know.
In fact, there is not much to "learn" here.
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What's so stupid.
With the 2.83V rating, you get dBA output directly.
The fact that an amp will provide varying current according to driver/loudspeaker impedance is not of great concern typically.
My vote goes to Simon.
Simon.....what PA's are you running/hiring ?.
Dan.
When I will grow up and gain good authority, I will burn Ed in a great fire.
Until these great moments, I have to keep some rationality and say that Ed is not that much of a witch.
He is not that powerful enough for to whip out the efficiency spec. He added sensitivity spec next to it .
In fact, specifications bound to specific impedance existed long ago in the engineering field (think dBm). It is customary for the narrow minded, block heads, antiprogressive engineers to swear by impedance.
So let him live (for a while).
The ones who I would burn right now is the driver manufacturers who market speakers also outside the professional engineers circle.
There , they should mention either efficiency (dB/1W/1m ) alone or both efficiency (dB/1W/1m ) and sensitivity (dB/2.83V/1m for 8 Ohm plus the impedance of the speaker at the freq of the spec)
George
Until these great moments, I have to keep some rationality and say that Ed is not that much of a witch.
He is not that powerful enough for to whip out the efficiency spec. He added sensitivity spec next to it .
In fact, specifications bound to specific impedance existed long ago in the engineering field (think dBm). It is customary for the narrow minded, block heads, antiprogressive engineers to swear by impedance.
So let him live (for a while).
The ones who I would burn right now is the driver manufacturers who market speakers also outside the professional engineers circle.
There , they should mention either efficiency (dB/1W/1m ) alone or both efficiency (dB/1W/1m ) and sensitivity (dB/2.83V/1m for 8 Ohm plus the impedance of the speaker at the freq of the spec)
George
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Jan
What is new is not the need for current, as mentioned that was known in vacumn tube days. It is the trade off of noise versus distortion. Or why do ICs that measure well not sound that way.
Phono preamps were an example. Bob Cordell showed a design using the LME family. With a 24.9 ohm feedback source resistor it has low noise. It also has a gain of 100 for a MM input. So the gain may be a bit high to get the chip into the optimal distortion output range. The load including feedback resistors is around 1450 ohms a bit too low for best distortion.
Now Bob is no slouch and his design is certainly at the state of the art. Could his design be improved by a lower input gain and compound amp/buffer input stage? Time and future designs will tell.
What is new is not the need for current, as mentioned that was known in vacumn tube days. It is the trade off of noise versus distortion. Or why do ICs that measure well not sound that way.
Phono preamps were an example. Bob Cordell showed a design using the LME family. With a 24.9 ohm feedback source resistor it has low noise. It also has a gain of 100 for a MM input. So the gain may be a bit high to get the chip into the optimal distortion output range. The load including feedback resistors is around 1450 ohms a bit too low for best distortion.
Now Bob is no slouch and his design is certainly at the state of the art. Could his design be improved by a lower input gain and compound amp/buffer input stage? Time and future designs will tell.
George,
I have yet to see a manufacturer actually use a real watt in attest set up. They just applied 2.83 volts and called it a watt!
Now the impedance is a different animal. The rated impedance is actually twice whatever the minimum is!
So using 1W/1M you only thought you had useful information. Now the knowledgable get a warning.
Then there is the silly issue that efficiency drops as level increases!
I also tried to get maximum power handling expressed in volts. That will never fly as the advertisors prefer the larger differentiation that comes from squaring the voltage.
I have yet to see a manufacturer actually use a real watt in attest set up. They just applied 2.83 volts and called it a watt!
Now the impedance is a different animal. The rated impedance is actually twice whatever the minimum is!
So using 1W/1M you only thought you had useful information. Now the knowledgable get a warning.
Then there is the silly issue that efficiency drops as level increases!
I also tried to get maximum power handling expressed in volts. That will never fly as the advertisors prefer the larger differentiation that comes from squaring the voltage.
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Dan,
I do stadium sound systems. JBL has the most suitable products, but not everything required. The current project uses Eat A Wieney brand. It is actually two ice rinks and a hotel. Last one was a 70,000 plus stadium. 105 dba without blowing drivers. JJ lives nearby so we got to play with it as a team. His daughter helped. (Just in case you have never tried to measure the results in all the seating of a stadium, it takes a week of climbing stairs up and down, up and down.... Very tiring, a real test of endurance! She was up to it.)
I do stadium sound systems. JBL has the most suitable products, but not everything required. The current project uses Eat A Wieney brand. It is actually two ice rinks and a hotel. Last one was a 70,000 plus stadium. 105 dba without blowing drivers. JJ lives nearby so we got to play with it as a team. His daughter helped. (Just in case you have never tried to measure the results in all the seating of a stadium, it takes a week of climbing stairs up and down, up and down.... Very tiring, a real test of endurance! She was up to it.)
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