• on Audio/Video/Photography
  • Published in issue 2/2003 on page 0
About the article

Active Loudspeaker System (2)

A subwoofer for use with multimedia loudspeaker systems

Active Loudspeaker System (2)
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.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor 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. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

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
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
D1 = LED, red, high-efficiency, 5mm
IC1 = TS924IN ST (Farnell)
IC2 = TDA7374B ST (RS Components)
IC3 = 7808
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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