• on Audio/Video/Photography
  • Published in issue 1/2003 on page 0
About the article

Active Loudspeaker System (1)

for multimedia applications

Active Loudspeaker System (1)
The 2-way active loudspeakers described here are primarily intended for use with a PC, but could in principle be used in any other ‘medium-fi’ application. Since the universal crossover filter can be adjusted to your own liking, you’re not tied to using the speakers and enclosure suggested here. Other woofer/tweeter combinations may also be used. An accompanying active subwoofer is currently under design and will be published in the near future.The starting point for this design was the irritation with the average to mediocre quality of the majority of PC loudspeakers. We thought that was something that could be improved upon without expending too much effort or money. Of course you don’t need the ultimate HiFi quality for the PC, but it would be nice to have a set of loudspeakers that gave a decent reproduction. In that way you could start to enjoy the music from a CD or DVD.
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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.

Resistors:
R1 = 1M?
R2,R15,R18 = 470?
R3 = 6k?8
R4 = 4k?7
R5 = 0?
R6 = 7k?68
R7 = 9k?53
R8 = 8k?25
R9 = open *
R10 = 4k?99
R11 = 9k?76
R12 = 12k?7
R13,R14,R16,R17 = 2k?00
R19 = 10k?
R20,R21 = 15k?
R22,R23 = 0?1 5W
R24 = 2k?7
P1,P2,P3 = 10k? preset
Capacitors:
C1,C4,C16 = 2µF2 MKT, lead pitch 5 or 7.5mm
C2 = 1nF, lead pitch 5mm
C3 = 120nF, lead pitch 5mm
C5 = open *
C6 = 8nF2, lead pitch 5mm
C7 = 3nF9, lead pitch 5mm
C8,C15,C18 = 3nF3, lead pitch 5mm
C9 = wire link *
C10,C11,C12 = 4nF7, lead pitch 5 mm
C13,C19 = 10µF 63V radial
C14,C17 = 470nF
C20 = 47µF 25V radial
C21,C23 = 100nF, lead pitch 5mm
C22 = 4µF7 63V radial
C24 = 4700µF 25V radial, lead pitch 7.5mm, diameter 17mm max.
Semiconductors:
D1,D2 = 1N4148
D3 = LED, green, high-efficiency
IC1 = TS924IN (ST, from Farnell)
IC2 = TDA7374B (ST, from C-I Electronics, www.dil.nl
IC3 = 7808
Miscellaneous:
JP1 = 2-way pinheader w. jumper
LS1 = SC13 8? Visaton (Conrad Electronics)
LS2 = SC10N 8? Visaton (Conrad Electronics)
Heatsink for IC2: 3 K/W
Wood: 12 mm MDF — see Figure 4
Wadding material (BAF)
PCB, order code 020054-1
* see text and Table 1
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