Circa 701 patents

     Thanks Wes for providing info about the original patents for the Electrohome Circa 75 prototype and the Circa 75 model 701.  To the right is the original artwork penned by someone in the art department of Electrohome back in the late 1960's - Perhaps Gordon Duern himself?  I always find it kind of funny the kind of things that get patented - this is essentially a patent on a round plywood cylinder covered with a teak veneer and stuck on a pedestal with a wooden spindle.  A *very* cool plywood cylinder, but a plywood cylinder no less.

     The second patent is the cabinet design for the prototype Circa 75 that now resides on display at the Waterloo Regional Museum in Kitchner, Ontario, along with other Electrohome goodies.  I'm still working on trying to get someone up at the museum to snap a few close-up photos of the prototype so we can get a good look at what the controls of one of the coolest pieces of 20th century design could do!

The Quest for a New Cartridge...

As much as I am a believer in keeping antiques (or in this case, mid century modernist pieces) in original, unrestored condition, I want to get the maximum possible sound quality out of this Circa 75 model 703.  Some really great people over at vinylengine.com have been trying to help me out with figuring out what kind of cartridge to get, and how to get the cartridge output to match up with the Circa's input voltages (the thread is here if you're interested).  The original cartridge is branded with the Electrohome symbol, but from what I've been able to piece together, it is an Astatic 183D, which is the original ceramic or crystal cartridge that shipped in the stereo console (photo 

Astatic 183D cartridge - the original cartridge from 1969.

to the right).  The first problem I've run into is that this particular kind of cartridge has rather high output of around 0.1 to 0.3 volts.  The modern, high-fidelity magnetic cartridge that I want to replace it with (Shure M97Xe) has an output that is an order of magnitude less at around 4.0 mV, or 0.004 volts.  However, the sound quality increase that should be achieved by switching out the cartridges means that I'm willing to undertake alterations.  This does mean that I will have to use a small ac powered phono preamp to boost the output from the Shure cartridge to something the Electrohome's amp can handle.  There are several small amps that can accomplish this relatively inexpensively.  And they are small enough that they can be easily concealed within the console, and wiring will be a snap.  The rca outputs from the turntable go into the preamp, rca cables from the preamp go out to the amplifier - couldn't be easier! 

 

Headshell from the Dual 1210 turntable showing the connector.

The second problem is that the Astatic 183D uses an internal clip for the wire connectors.  The Shure, on the other hand, uses the more typical type of connectors where there are male leads coming out the rear side of the cartridge body (see clip on lower photo to right).  This means that I'll either have to: 1) alter the connector to something that the Shure cartridge can take; or 2) use no plastic connector at all.  So all of the tiny little wires you see to the right carry the signal from the stylus to the amplifier, four wires = a positive and a negative for each channel, four wires total.  I may solder new wires into the headshell that just have a female connector on each wire, then I can just push the individual connectors together and mount the cartridge that way.  Waiting to order the new cartridge until I hear back from the people at Vinylengine.com to confirm weather my plan will work first.

IT'S ALIVE!

The Circa 75 model 703A showed up this past Saturday morning bright and early.  The shipping company did a great job with the blanket wrap - it was very satisfactorily padded.  Got it into the apartment and took off the nearly roll of packing tape holding the blankets on and finally got my first look at it!  It is in remarkable condition - no scratches or dings at all in the round teak casework, only minor paint chips on the upper black enamel lid, a few chips on the black enameled tambour doors, and the inside was quite dusty (see photo, right), but otherwise, everything

looked great!

Circa 75: Space Age Beginnings

The success of the Clairtone Project G series prompted Electrohome, a Kitchner, Ontario based company to try its hand at producing a modern, space age stereo system¹.  However, instead of copying the purely esthetic ‘space-age’ look of the Clairtone Project G’s, Electrohome instead actually looked to the Canadian government’s space program for ideas¹.  Gordon Duern, Electrohome’s design director, dreamed up the Circa 75 prototype (now housed at the Waterloo Regional Museum in Kitchener, Ontario, Canada) to try and emulate Canada’s satellite Communication program¹.

...so you just bought an Electrohome 'Circa' series...

...and you can't find any information at all on the internet.  This is the very reason this blog exists.  I just bought this beauty on the left, and, after an incredibly frustrating few days of research (I also did research BEFORE buying it), I have been unable to turn up much information. So I am going to use this bit of webspace to share some of the information that I have found