Technics SB-M300 M2 crossover restoration
Introduction
I use very rare Technics SB-M300 M2 speakers. After 15 years of using, I decided to look inside and replace old
NPE caps by new
BENNIC
metallized polypropylene film capacitors.
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Crossover schema
Two woofers are directly connected to input terminals. Crossover PCB (SUPP98-2A) is accesible after removing tweeter.
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New crossover
New crossover have identical schema for mid+high range, but for woofer I added LC filter to cut-off high frequencies. Of course big caps is not possible to place inside reprobox, so crossover must be external.
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Material list
Crossover mid + high range | |||
---|---|---|---|
Mark | Type | Amount | Note |
C1 | 3M9 160VAC/250VDC | 2 | capacitor ![]() |
C2 | 10M 160VAC/250VDC | 2 | capacitor ![]() |
C3 | 4M7 160VAC/250VDC | 2 | capacitor ![]() |
C5 | 47M 160VAC/250VDC | 4 | capacitor ![]() |
Crossover low range | |||
L6 | 2,2 mH – wire 1,25 | 2 | inductor ![]() |
C6 | 10M 160VAC/250VDC | 2 | capacitor ![]() |
Other | |||
AEC BI-204 | 4 | repro connector pair ![]() |
|
121051 | 4 | repro connector pair ![]() |
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Cinch female | 4 | panel mount |
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