Sunday, December 19, 2010

I think we're overdue for some gratuitous gut shot.

For this, we'll dig into a mid 1960s Cordovox accordian tone generator, essentially organ guts in a gig-able package.

In my preliminary searches I've narrowed the model down to a Cordovox CG, though I see no reference to a specific model on the number plate.

The complete system was composed of the tone generator bank (above); the power supply & amplifier, encased in a similar box with a 2x12 speaker baffle as opposed to the louver behind the grill cloth; and an accordion controller attached with a robust cable and multi-pin connector.

So it stands within reason that a switching bank feeding a couple DB-50 male connectors could put this thing to work. Sadly, I've no accordion controller handy to emulate.

Of course, use hinges on the functionality of the circuit. The deceptively simple control panel sits atop a convoluted wall of circuitry.

A bunch of 6X8 and 6FH8 in the oscillator stacks.

Oh yeah, much better. I believe those two lamps are there to keep interior temps warm enough to prevent condensation.

Oscillators look to be relaxation oscillators built around early integrated RC network packages and neon lamps. I'm betting this unit looks very cool in use (well, if you have X-Ray vision to see through that damn baffle).

Loads of prepackaged circuit components in use here, this thing would be a nightmare to do major replacement surgery on. A discrete point to point rendering of this circuit would be a sight to behold.

Since I'm more or less completely in the dark as to the feature set of this generator, I can only wager a few thoughts to the purpose of this hub or the leaf relay (which actually has 13 tines, the leftmost one being discolored or burnt), my main guess being that these parts support chords.

I had the bright idea of trying to bring this unit up on the variac yesterday, only to realize after the cracking the case that I needed the power amp section (which was left in storage) to supply power to this stage. This particular set came from the bad amp room haul, this was one of the more exciting elements of that haul, as I've had another pair of the same for a long while that had the tubes plucked from the oscillator banks making the possibility of tinkering slim.

Still, this one sits low enough on the priority scale to qualify as a casual project to be chipped away at with an air of nonchalance.


Homestudy said...

Just wondering how this worked out? I just picked one up today.

Homestudy said...
This comment has been removed by the author.
Homestudy said...

Just wondering how this worked out? I just picked one up today.

crochambeau said...

To be honest the Cordovox project has not made it to the top of my project pile yet. Though sometimes someone tangling with another out in the wild will inspire me to dig mine out... Does yours have the accordion controller, or is it just the electronics?

Matti Kari said...

The circuit is very similar to my Lowrey Heritage DSA organ from the 60's. Sounds are also very similar!

The Hammond Solovox has similar looking round box that contains a few relays to trigger different octaves from the controller keyboard. Could be that or something completely else.