R. R. Cordell 10/18/03

Athena

R. R. Cordell 10/18/03

Athena

R. R. Cordell 10/18/03

Athena

SYSTEM 3.5-Way self-powered TMWWWW 37 X 7 X 16 mini tower built-in 4-channel amplifier per box time-aligned, transient accurate sloped baffle (11 degrees) Equalized Quasi Sealed System (EQSS ) adjustable electronic baffle step compensation

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DRIVERS Vifa D27TG-35-06 silk dome tweeter Vifa TC08WD49-08 3.5-inch midrange four McIntosh 5.25-inch woofers

– fs: 55 Hz

– Vas: 15.5 L

– Qts: 0.35

– Xmax: 2.5 mm

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ACTIVE CROSSOVER 750 Hz and 4000 Hz first order electrical 200 Hz constant-voltage half-way cross twin-tee passive 9 kHz midrange notch EQSS biquadratic LF equalizer electronic Baffle Step Compensation adjustable BSC (amount and frequency) signal sense for auto turn-on

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AMPLIFIERS four 125 Watt power amplifiers per box MOSFET output with JFET input boosted driver supply for max headroom flying catch diodes for non-saturating clip symmetrical, stick-free clipping high current design stable to < 2 ohms clip indicator

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AMPLIFIERS (cont.) folded complementary push-pull driver fast, low-voltage output stage drivers servo-controlled output offset no capacitors or inductors in the signal path small physical size 70 V/us slew rate < 0.03% THD to 20 kHz @ full power

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AMPLIFIERS (cont.)Flying Catch Diodes

limit max gate-source voltage prevent driver saturation in clipping provide adaptive symmetrical clipping prevent saturation of folded EF drivers prevent reverse base breakdown in EF drivers prevent driver damage from output device short

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EQSS System objective - big sound from small box 9 liters per 5.25-inch woofer 53-Hz woofer f0 box tuned to 37 Hz - 3dB @ 35 Hz, second order, Q=0.7

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EQSS THEORY Quasi Sealed System:

– ported, but box tuned very low– resulting response approximates sealed system

Equalize as if a sealed system– use parameters of sealed system it approximates

port increases LF excursion-limited SPL transient response like that of sealed system applicable to subwoofers as well

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POWER MANAGEMENT auto turn-on at signal detect 5 minute on time in absence of signal inrush current control speaker relay delay control