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Substituting drivers
in the PA speaker

In the September 1996 issue of SILICON CHIP there was a project for a "high-quality loudspeaker for public address". The specified speakers (P17WG-00-08 and AD11600/T8) are hard to find now. Do you know of equivalent speakers that are readily available? (S. P., via email).

  • Philips AD11600/T8 tweeters are now unavailable and the Vifa woofers are also hard to get. However, the designer of the project has since made an equivalent PA speaker using four C3086 165mm woofers and four C3003 25mm dome tweeters, from Altronics in Perth.
  • The design is similar to the original but with the following changes: First, the box is changed from 750 x 370 x 460mm to 800 x 440 x 440mm for a nominal internal capacity of 100 litres using 18mm MDF. The spacing between woofers and tweeters is 150mm; tweeter-to-tweeter spacing is 55mm; woofer-to-woofer spacing is 185mm. Port to tweeter spacing is 55mm.

    The ports require a 65mm hole while the tweeters require an 80mm hole counter-bored to 104 x 4mm deep. The woofers require a 150mm hole counter-bored to 175 x 4mm deep. The two speaker ports are each 50mm in diameter and 200mm long.

    The crossover arrangement is as per the 1986 design, with the two 3.2μF capacitors each used for the high-pass and the low-pass filters changed to 4.7μF. The inductor for the woofer crossover is changed from 0.82mH to 2.7mH. The inductor for the tweeter crossover is changed from 0.82mH to 0.56mH.

    The 10μF/12ω ohm shunt network across the woofers becomes 10μF and 8ω. The attenuators for the tweeters change from 3.9ω and 10ω to 3.9ω and 8.2ω, respectively.

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