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A. Rebuild
B. Listen
C. Specs

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Worthingtons Workshop

High Fidelity

Close Tower Loudspeaker

Description of this page

The Close Tower Loudspeaker is a narrow front two way bass reflex floor mounted loudspeaker. The two enclosures were originally found on the roadside with punctured tweeters and missing grilles. This is basically a rebuild to bring it back to near factory originality for inclusion in a mates audio/visual system. Surprisingly the total cost of the rebuild came in at just on $100, which is a welcome respite from the high priced rubbish usually available in rural towns.


Close speakers original


Close speakers tweeter mount


A. Rebuilding the Speakers

The Close Loudspeaker was intended as a cheap replacement for a set of failed home theatre speakers. A friend had expressed a desire that I keep him in mind if ever I disposed of a set of speakers. Fortuitously these had appeared recently on the side of the road and are for the most part in reasonable condition. They were found with the tweeters destroyed and the grilles missing.The overall image I get of the system is a Chinese knock-off of a Bowers and Wilkins 600 series speaker system, due to the tweeter mount arrangement and the colour of the woven cones.

The woodwork is vinyl covered MDF with simple bracing, to which I added Insulwool sound deadening. An Altronics C3010 19mm dome tweeter was chosen as it was a proven driver in another design and was extremely cheap. It required an aluminium mounting plate to be fabricated and installed onto which the tweeter was mounted. The two bass drivers are wired in parallel. The delicate rear terminals were replaced with a decent Jaycar sourced set and the crossover was simply a 4.7uF (measured 4.88uF) capacitor in series with the tweeter, giving a 5.3kHz crossover frequency. Rewiring was done with fresh braided twin core wire.

The baffle was cut from 3mm MDF with holes cut for the three drivers and four removable mounting plugs, to enable cleaning. The grille is a black acoustically transparent cloth glued to the baffle using spray on Selleys Kwik Grip glue. A pair of cardboard ports were replaced by a Jaycar plastic set of exactly the same dimensions, glued in and giving a much more professional appearance to the front. Plastic feet were added for protection of polished wooden floors.



Close speakers with drivers mounted


Close speakers with grilles added


B. Listening to the Speakers

Cons:
1) Slight hole in the midrange, due to roll-off in the response of the bass/midrange drivers.
2) There is also a very slight honkiness on some source material due the off axis response falling.
3) When pushed to loud levels, distortion becomes evident.
4) Slight inefficiency with regard to other speakers I have compared.

These cannot be improved without replacement of the drivers, but this is not what this project was about.

Pros:
1) Realistic reproduction of voice due to the quality of the bass/midrange drivers.
2) Airy top end due to excellent tweeters.
3) Punchy extended bass. I was surprised how deep the bass went.
4) Fast response - stop/start effect with no overhang due to low mass cones.
5) They go quite loud. I had them playing musically in the workshop and was listening to them in the loungeroom.

Conclusion:
I think these are a reasonably decent set of speakers, although slightly tatty due to previous use and the manner in which they were acquired. Acoustically they are the equal of a lot of medium priced speakers on the market and should be an adequate addition to a Home Theatre system. I'd recommend anything up to a 30 watt/champlifier, capable of being listened to at a mid level volume control setting.

Test tracks used were Sade - 'Smooth Operator' and Tears for Fears - 'Year of the Knife'.


C. Specifications of the Speakers

Specifications : Two Way Narrow Fronted Bass Reflex Floor Mounted Loudspeaker
Dimensions : 900mm High x 195mm Wide x 252mm Deep
Enclosure : 35L Braced and Lined
Efficiency : 86dB at 1W at 1 metre
Impedence : 3.3ohms typical
Power Handling : 30W rms
Crossover Network: 5.1kHz 1st Order Butterworth Network
Bass Driver : Paper Cone Woofer 140mm with aluminium dome (Chinese unnamed).
Bass/Midrange Driver : Paper Cone Woofer 140mm with yellow woven cone (Chinese unnamed).
Tweeter Driver : Dome Tweeter 19mm (Altronics C3010)