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F.A.S.T.-Monitors Revived

The Story

About 10 years ago I built my first actively crossed over speaker project. The concept is of the "F.A.S.T." type - Fullrange And Subwoofer Technology. Back then they were used as near-field monitor speakers for our small basement recording studio and they were built in a fast-and-rough style. Enclosures were made of 19mm MDF with a 2L cabinet for the Tangband W3-315 aluminium-magnesium cone 3 inch fullrange and a approx. 20L ported cabinet for the Tangband W69-1214 Woofer. The were actively crossed over at 150Hz with LR-12 filters using OPA2132 Opamps and were bi-amped by a pair of LM1876 chip amps.

Despite their very simple and boxy enclosure and the very simple crossover circuit they still sounded great!

Since then I learned a lot about speaker design. And since I got them back a while ago I decided to revive them with a better enclosure and a more suitable crossover using Pulseaudio Crossover Rack. The side and top baffles were doubled up with 19mm MDF and 18mm birch plywood for the front baffle to make a large radius at the edges possible. The port was closed up and the bass response will be equalized flat down to ~35Hz.
The active crossover electronics were ripped out and an additional input was added to make the amp a true 4 channel amplifier to be fed directly by the outputs of a (>=) 4 channel soundcard. The PaXoverRack file can be found below. Measurements will hopefully follow soon...

Listening Impressions


Photos and Files

Name Size Type
Old schematic of crossover and amplifiers.T3001 229.2 KB application/octet-stream
Old schematic of crossover and amplifiers.PDF 70.5 KB application/octet-stream