14 July 2013

Cheap Open Baffle Speakers (COBIES)

Bruce has put together a pair of Cheap Open Baffle Speakers - the COBIES.  Relative to most DIY speakers this open baffle project will be quite easy to build.  One of the main design goals for Bruce was to keep the total parts cost under $150US.  The open baffle speaker project was inspired by the "Big Air" open baffle system by Jim Strasser.  

Cheap Open Baffle Speakers
COBIES - Cheap Open Baffle Speakers
Each open baffle uses a GRS 12PF-8 woofer and two Goldwood GT-25 paper cone tweeters.  One tweeter is mounted on the rear of the baffle pointed upwards about 45 degrees.

Rear Mounted Goldwood GT-25 Tweeter
Rear Mounted Goldwood GT-25 Tweeter
Bruce experimented with various crossover points settling on 3.6 kHz finding that lower crossover points put too much of a demand on the GT-25 tweeters.  Using a calibrated microphone and RTA the in-room response from 100 Hz to 10 kHz was quite smooth and free of any large irregularities. Response below 100 Hz was affected by room nodes but quite good down to 40 Hz.  Above 10 kHz was certainly excellent (up to about 18 kHz).  The overall speaker system sensitivity is estimated at 93 dB / 1 watt at one meter. Bruce uses a pair of 5 watt (each) tube mono block amplifiers (EL84 PP) with the open baffle speakers. 

"The sound is something you will either love or hate. As I said earlier open baffle speaker systems are bi-polar. I really like it, some individuals will not. The speakers have an excellent overall sound. They have a lot of ambiance and provide a good listening experience. Bass is quite clean and robust ..."

Full details are available on the  COBIES (Cheap Open Baffle Speakers) project page.  Comments and questions about this project are welcome in the Open Baffle Speaker Project thread.

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