Posted by Terry Koehn on September 16, 2002 at 23:24:18:
In Reply to: Re: Re: M-1 Sensitivity posted by Marcos Augusto on September 15, 2002 at 00:56:09:
I'd also like to read this review....I'm so not sure Test Equipment designed to test Cone/Box speaker systems will ever accurately measure ESL panels.
A word about accurate testing ?: A condenser test microphone with 1/2 inch diaphragm positioned 3'feet in front of a full Surface Radiating 6'Foot ESL Panel that doesn't focus until 30 feet back and actually increases in perceived volume with the increased distance.... Is not a very good ESL test.
At this point in time we don't even have an accurate way to Direct Drive ESL Speakers Panels.Because all the amps have been designed to drive Hi-Current Permanent Magnet Cone /Box speakers. ESL Panels want to see Hi-Voltage Push-Pull Swing Voltages [5-16 KHV ]....Not Hi-current magnetic force.
The direction lately has been to use very low output impedance Hi-Power Amplifiers with lots of output tubes to drive Full Range ESL Panels...But All that current power is not for the ESL Panel...It is for the Step-Up Transformers Crossovers trying to match drive conversion the drive Hi-Voltage that the ESL panel needs to be driven to volume...
By the time we hear sound from a Full Range ESL Panel it has been through [3] Transformers : The amp output Trans. ,The bass Drive Step up trans,The Hi-Midrange Trans...
Even the Amp. with no Output Trans. still look through [2]Transformers before it is able to excite the ESL panel...
My point is: Most of the test is really reading the low efficient Crossover Step-Up Conversion, not the ESL panel...
We need to start think outside the Low Impedance BOX...Tubes like Hi- Impedance...ESL Panels like Hi-Voltage,Hi-Impedance..Why are we still trying to convert both Speaker & Amps to under 10 Ohms????