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ErnestC
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Joined: Mar 11 2009 - 4:09pm
Using (ECG) Electronic Crossover Gain Testing

Hi I'm new to the forum.
I'm a long time subscriber to the magazine , , , also a very long time advocate of what has been termed the 'high end.' As a former aerospace engineering scientist I've had the capability to usually build better audio equipment than I could afford to purchase. In doing so I boned up on on my acoustical studies to better understand the relationship between sound generation and psychoacoustics.
This led to unconventional testing procedures for the development of loudspeakers in the late 60's. Using a similar protocol to that used in testing the human heart (EKG), I developed a testing procedure called ECG (Electric Crossover Gain) testing. Just as EKG measures the signal flowing in the human heart muscle, ECG measures the voltage applied directly to the voice coil of a loudspeaker as installed and acoustically loaded by the enclosure and the room.
This procedure requires bringing out to an external connector, wires connected directly to the voice coils of each transducer. Not all manufacturers will accommodate the reviewer with such a convenience.
By comparing the voltage vs. frequency plots of the ECG with the anechoic acoustical plots, the anomalies of the transducers, the enclosures and those determined by speaker placement on the baffle can be determined quickly so that few iterations are required to develop a loudspeaker system. Such a procedure aids a reviewer in advising the manufacturer or the diy hobbiest where noticeable improvements can be made.
Such anomalies as cone breakup, resonance and crossover ringing,mismatch at the crossover points, unwanted port
resonances, impedance mismatches, inductor saturation and inductor magnetic cross-coupling, and unwanted box resonances can all be detected after developing experience with the procedure.
Since this is my first visit to your forum, I think that I've probably said enough for our initial introduction. Should anyone choose to comment or contribute . . please post a response on the forum.

Thanks, Ernest W. Cassadat

ethanwiner
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Joined: Sep 1 2005 - 2:26pm
Re: Using (ECG) Electronic Crossover Gain Testing


Quote:
ECG measures the voltage applied directly to the voice coil of a loudspeaker as installed and acoustically loaded by the enclosure and the room.


Sounds like a very cool idea that has real practical value.

--Ethan

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