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High Fidelity

Oscar

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A. Design
B. Listen
C. Specs

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Worthingtons Workshop

High Fidelity

Oscar Stand Mount Loudspeaker

Description of this page

The Oscar Standmount Loudspeaker is a narrow front three way bass reflex floor mounted loudspeaker,
built as a project for a mate to complete a classic high fidelity system.



Oscar speakers in lounge room


Oscar speakers front view

A. Designing and Building the Speaker

The Oscar Loudspeaker was designed for a old mate of mine who is no longer with us. It was created as a cost effective monitor to enable him to listen to his vast LP library. The speakers were a match for a large restored Pioneer 50 watt/ch amplifier, and Dual 1219 turntable. The speakers took about eight years to build, from initial thoughts of "Bob, I would like you to build me a good set of speakers...", to final delivery. Oscar supplied the timber, and I bought the components. He thought it was well worth the wait, and was extremely happy with the results. The total cost was about $700.00 for the pair.

We decided on a bass reflex design for extended bass response and efficiency. The cabinet is thoroughly braced and insulated to my usual standards, so that it passes the knuckle rap test beautifully. This was the first bass reflex I have built, and would now consider bass reflex designs for further speakers. The rest of the speaker is conventional, except for the use of Linkwitz crossovers. Crossover assembly was done using hand wound coils for low DC resistance (actually wound on a workmates lathe), mounted on Jaycar CX-2605 Crossover PCB's - a practice I heartily recommend.

The Bass driver was originally twin coned. The Secondary cone was removed by carefully tearing around the glued inner join to the main cone and then carefully repositioning and re gluing the vented dome. The main cone was then doped with Aquadhere PVA and set to dry. The midrange driver is a good replacement for the previously used Fosters C100K03 - now sadly no longer available. It too underwent the cone doping process to improve midrange accuracy and transient performance. I believe the Tweeter to be a Chinese copy of a Peerless driver as the performance is exceptional. The tweeters are mounted under the midrange drivers to keep the midrange at ear height, give a time delay to the tweeter and to give a larger enclosure for the midrange driver.


B. Listening to the Speaker

The Sound quality is reasonably neutral, with a suprisingly extended but not overwhelming bass response. They certainly fulfill their design criteria as being suitable for fatigue free listening to classical records at low and medium volume levels. I managed to surprise Oscar by demonstrating the ability of the system to image a soundstage in multiple dimensions. He enjoyed the system for a number of years, although he never got around to finish the cabinets with any veneering or staining.


C. Specifications of the Speaker

Specifications : Three Way Narrow Fronted Bass Reflex Floor Mounted Loudspeaker
Bass Enclosure : 65L Braced and Lined
Midrange/Treble Enclosure : 6L Braced and Lined
Frequency Response : 50hz - 22,000hz at -3dB
Efficiency : 88dB at 1W at 1 metre
Impedence : 6.5ohms typical
Power Handling : 30W rms
Crossover, Bass - Midrange : 800hz 2nd Order Linkwitz Network
Crossover, Midrange - Tweeter : 3.5 kHz 2nd Order Linkwitz Network
Impedence Correction : Woofer, Midrange and Tweeter Voice Coil Inductance
Bass Driver : Magnavox 8WR Paper Woofer 200mm
Midrange Driver : Altronics C0635 Cone Midrange 100 mm
Tweeter Driver : Response CT-2010 Dome Tweeter 25mm (Jaycar CT-2010)