Alternative MG-1.5/QR Schematic

resistorless midrange boost

Ed G proposed adding resistors in series with Magges to cut the treble & bass, but virtually ignore the midrange XO point. Adding resistors has consequences in addition to 5dB reduced efficiencies, which are elaborated here.

1st ORDER HIGH-PASS FILTER

CT' ≡ CT(ZT+RT)/ZT
= 15μF ( 2.7Ω + 3.5Ω )/ 3.5Ω
≈≈ 27μF

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2nd ORDER LOW-PASS FILTER

LB" ≡ ZB(LB + CBRBZB)/(RB + ZB)
= 3.9(3.75e-3 + 10e-63.33.9)/(3.3 + 3.9)
≈≈ 2.1mH
CB" ≡ CBLB/(LB + CBRBZB)
= 10e-63.75e-3/(3.75e-3 + 10e-63.33.9)
≈≈ 9.7μF