The Secret Society of Lathe Trolls

blacknwhite · Joined: 24 Apr 2008 Posts: 7

Browsing US patent dbase & found this 1936 Bell Telephone patent for 45/45 stereo cutterheads: Amazing, had no idea, thought some might enjoy. There could be experimental 1930s 45/45 stereo shellac 78s in a lab somewhere...

http://home.nc.rr.com/goodmusic/1936_45_45_stereo_cutterhead_2114471.pdf

- Bob

cuttercollector · Joined: 11 Jun 2006 Posts: 219 Location: San Jose, CA

Did not read the whole thing but it does seem to show both vertical/lateral and 45/45 designs. As little as 2 years before this they were experimenting with vertical/lateral left and right cutters. Bell telephone put out an Lp of this early material sometime in the 1960s or 70s, which I have. The reason it was Bell is because it was Bell Labs Western Electric division doing the experimentation. That name got shortened eventually after it was split off from the phone company as Westrex. Western Electric did important development work in the US on both disc cutting and film sound and were the main US manufacturers of this pro equipment for the greater part of the 20th century. I think Blumlein in England actually did the first 45/45 experimental cutter as well as the ribbon mic and stereo optical film soundtracks very early on. There is lots of stuff on line about all of this but it is interesting to see the patent documents themselves.
BTW, there is an interesting relationship between vertical/lateral cutters and 45/45 ones and stereo vs. M/S or sum and diference mic techniques.
Fairchild's 60s stereo cutter actually was a vertical/lateral cutter driven with a sum/diference signal which produced a perfectly compatible stereo recording like all the other 45/45 cutters driven with a conventional L/R stereo signal. The reason is that an actual stereo groove contains the sum of the L/R channels in the lateral direction (backwards compatible with mono) and the diference between the 2 groove walls causes a vertical movement with the diference between the L & R channels.
Don't know if anybody ever built a playback cartridge using a vertical & lateral element instead of 45/45, but it is possible. You would then need to run it through an M/S phase decoder to get back your stereo signal from a normal stereo record. If you played back the early experimental discs recorded L = vertical R = lateral with a modern stereo pickup you would get M/S sound until you ran it through the same M/S phase decoder where it would turn back into L/R.

blacknwhite · Joined: 24 Apr 2008 Posts: 7

Very cool info Cuttercollector, thanks. Hadn't put 2 and 2 together yet, Western + Electric = Westrex... That explains a lot.

Yes, having a vertical/lateral stereo cutterhead would also make it more direct to suppress excessive vertical stylus movement in the cutting process.

Just found an even earlier stereo disc patent that pre-dates that last one by about 20 years:

A 1915 (!) patent for stereo Acoustic grammophone cutting & playback (vertical & lateral): Actually many of the players made about that time had twist-able playback heads to play Either vertical Or lateral mono, so seems a logical conclusion... Imagine, lost experimental stereo early jazz band discs... funny

http://home.nc.rr.com/goodmusic/1915_stereo_separate_vertical_lateral_1342442.pdf

And seems someone came "this close" in 1898 to making stereo cylinders, with an attempt at improving cutting volume/quality, if they'd just powered the drivers with Separate Horns...

More funny stuff, this is entertaining... 1921's dual-groove stereo disc:

I've had enough, the great outdoors is calling, will organize & post a list of record-cutter-related US patents with links soon, for others amused by this stuff.

- Bob