1939 Novachord - 163 Tube Monster!!

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Some of you might be interested in the major restoration project I've been working on for several months now. I have returned Novachord 346 back to working order having imported this extremely rare 1/4 ton all electronic instrument built in 1939 from the US containing 163 tubes!!!

The Novachord was the world's first commercial polyphonic synthesizer. Amazingly, it has full 72 note polyphony, a VCA and envelope generator for every key with an envelope control on the front panel, a three stage resonant band pass filter and a 6 channel electromechanical vibrato system.

The Novachord cost $1800 in 1939 ie. as much as a house!!

The instrument found it's way into countless Hollywood SciFi and horror films in late 30's up to the late 60's.

Only 1069 were built due to WWII and some stability issues. The instrument was simply decades ahead of it's time and one of only two instruments Hammond ever made that specifically -wasn't- designed to emulate the sound of an organ.

Having ploughed hundreds of hours returning her to working order we went on to produce the world's only pro sample archive which has resulted in 346 being immortalised to great effect in the music score of the multi-million dollar XBox 360 game, Alan Wake, due to be released soon.

Novachord 346 is now one of less than 40 known working examples world wide and the only example in the UK - hence my excitement!!

Here is a duet we recorded with a Theremin recently with the Novachord:

YouTube - Novachord and Theremin duet

Here is a video of me demonstrating the beast:

YouTube - Novachord video

You can see/hear much more at our website: www.novachord.co.uk
 

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A truly wonderful project and lovely sound. A Theremin duet is icing on the cake (what kid didn't fall in love with it in 'The Day the Earth Stood Still'?) If those are banks of small PIO caps along the back rows, Soviet K40Y9's from Ebay might be suitable replacements.
 
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Amazing! I'm in awe of the Novachord -- and of your work. :eek:

When I was young and naive, I thought all electronic organs had a tube oscillator for every note. But where did they hide them all? I can hear now why it was done - and see why it was done no more!

Much thanks.
 
A little over 10 years ago I knew 2 guys that had a recording studio in Burbank, CA and they had 4 of these Novachords. Their intention was to rebuild all 4 and do a tribute recording of the one made at the 1939(?) World's Fair, that used 4 Novachords.
I recall working on one of these instruments and there was so much inside of it. The main problem these Novachrods have, if I recall, was that the timing capacitors for the tone generators were all leaky. The hard part was that we had to start at one end of the machine and measure the capacitance of each cap and change it if it was more than 5%(?) or so, off. And each successive cap was dependant of the value of the cap preceeding it. Very tedious work. In, the end, I think 2 of the 4 were restored.
Good job! How did you do it without breaking your back?
Daniel
 
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Firstly - thanks for all the kind comments, it means a lot! Restoring 346 to playable order was a pretty major undertaking but in my opinion it was well worth the trouble :)

They look like 6L7G tubes. Am I right?

Well not quite but it's the right era....

The Novachord's generator chassis consists of 146 tubes broken down into 12 6C8G triode based oscillators, 72 6W7G based non-linear monostable circuits, 72 6W7G based VCA circuits, a 6J7G preamp utilising a variable capacitance volume pedal running in a degenerative feedback loop and the phase spitter transformer drive with a 6J5G on the primary.

The power supply is extremely impressive for a 70 year old design. It produces 7 voltage rails using 10 tubes. Two of the rails are active noise cancelling whereby any ripple and harmonics created by the generator chassis are negated without the need for expensive smoothing caps! The circuit is extremely effective - on the 270V rail the ripple is reduce from 30 volts pk-pk to 500mV - this can be demonstrated by pulling the final 6K6 and then plugging it back in again - as the tube warms up the ripple magically disappears!!

I have attached some of the circuit diagrams for your amusement.

The PSU needed the most attention in the case of 346. Very thankfully she had been owned by a talented electronic design engineer (in fact an early pioneer of tube based computers!!) and clearly maintained over the years. The vast majority of 346's generator is just about within calibration despite over 80% of the non polarised wax paper foil capacitors and 95% of the tubes being the 70 year old originals!!

The PSU, on the other hand, was a right off and was very badly damaged due to a sustained short circuit on one of the supply rails thanks to one of the potted multi-caps in the preamp going dead short circuit. I had to strip the entire PSU down to the bare chassis and rebuild it with new components - even the two mains transformers and one of the chokes had to be cloned as one of them had actually caught fire!! It turned out to be a pretty major job!

346 is not perfect but is one of the most original working examples in the world. The only thing I and some other owners have put to one side is the PA chassis as although it was amazingly powerful, with four 2A3 tubes, for the era with two 12" Jensen A12 energised loudspeakers, it had a very poor frequency response. After fitting a balanced line output at the phase splitter transformer output, it became clear that the Novachord has an amazingly wide frequency response for such an old design.
 

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WOW! Congratulations on a job well done!
Reminds me of a project I started in the 70's. I (like quite a few other brave/foolish souls it seems) tried to build a big synth that came out in the Aussie mag ETI. It also came out as the Maplin 5600 in England. It had about as many CMOS 4000 series chips as you have tubes in the 346. And it was monophonic.
Never got it working sadly.
 
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