Article
Active Loudspeaker System (2)
A subwoofer for use with multimedia loudspeaker systems
As with most small enclosures, the bass response of the active 2-way loudspeakers described last month has its limits. The compact subwoofer described here will therefore be a welcome addition for most enthusiasts. With its adjustable filter this subwoofer will also work very well with other small (satellite) speakers.As a rough guide the bass response of loudspeakers tends to improve in proportion to their dimensions. This is not completely true, since there are a few tricks that can be used to get a reasonable bass response from a relatively small enclosure. But these come at a cost of a reduced power handling capacity, efficiency and sound pressure level that the loudspeaker can produce.
Gerber file
CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.
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PCB
Component list
Resistors:
R1,R2 = 220k?
R3,R4 = 22k?
R5,R6 = 4k?7
R7-R11 = 10k?
R12,R13 = 0.1? 5W
R14 = 2k?7
P1 = 22k? logarithmic. mono
P2 = 4k?7 linear. stereo
Capacitors:
C1,C2 = 470nF
C3 = 1nF, lead pitch 5mm
C4 = 330nF, lead pitch 5mm
C5 = 15nF, lead pitch 5mm
C6 = 150nF, lead pitch 5mm
C7 = 2µF2 MKT, lead pitch 5 or 7.5 mm
C8,C9 = 47µF 25V radial
C10,C13 = 100nF, lead pitch 5mm
C11 = 10µF 63V radial
C12 = 4µF7 63V radial
C14 = 4700µF 25V radial, lead pitch 7.5mm, max. diameter 17mm
Semiconductors:
D1 = LED, red, high-efficiency, 5mm
IC1 = TS924IN ST (Farnell)
IC2 = TDA7374B ST (RS Components)
IC3 = 7808
Miscellaneous:
JP1 = 3-way pinheader with jumper
LS1,LS2 = Visaton W170SC 4 ? Conrad Electronics)
2 x bass reflex tube, diameter 72mm, length 145mm (Conrad Electronics # 34 26 10-60)
Heatsink: e.g., SK100 (Fischer), height approx. 50mm *
Sealant tape: MDM-5 (Monacor/Monarch)
BAF wadding
PCB, order code 020054-2
* see text
R1,R2 = 220k?
R3,R4 = 22k?
R5,R6 = 4k?7
R7-R11 = 10k?
R12,R13 = 0.1? 5W
R14 = 2k?7
P1 = 22k? logarithmic. mono
P2 = 4k?7 linear. stereo
Capacitors:
C1,C2 = 470nF
C3 = 1nF, lead pitch 5mm
C4 = 330nF, lead pitch 5mm
C5 = 15nF, lead pitch 5mm
C6 = 150nF, lead pitch 5mm
C7 = 2µF2 MKT, lead pitch 5 or 7.5 mm
C8,C9 = 47µF 25V radial
C10,C13 = 100nF, lead pitch 5mm
C11 = 10µF 63V radial
C12 = 4µF7 63V radial
C14 = 4700µF 25V radial, lead pitch 7.5mm, max. diameter 17mm
Semiconductors:
D1 = LED, red, high-efficiency, 5mm
IC1 = TS924IN ST (Farnell)
IC2 = TDA7374B ST (RS Components)
IC3 = 7808
Miscellaneous:
JP1 = 3-way pinheader with jumper
LS1,LS2 = Visaton W170SC 4 ? Conrad Electronics)
2 x bass reflex tube, diameter 72mm, length 145mm (Conrad Electronics # 34 26 10-60)
Heatsink: e.g., SK100 (Fischer), height approx. 50mm *
Sealant tape: MDM-5 (Monacor/Monarch)
BAF wadding
PCB, order code 020054-2
* see text
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