The Secret Society of Lathe Trolls

motorino · Joined: 24 Aug 2005 Posts: 212

hello

I have this vintage cutter, and before burning it ... I would like to know some tech datas, like maximum permissible drive current or maximum power, or its curve of frequency response...use transco #362 stylus? all information its welcome

thanks! and merry chrismas!

flozki · Joined: 19 May 2006 Posts: 55 Location: switzerland

hei. what about a picture of the head? would be nice maybe i have some data...

motorino · Joined: 24 Aug 2005 Posts: 212

big thanks Very Happy

motorino · Joined: 24 Aug 2005 Posts: 212

andybee · Joined: 14 Aug 2006 Posts: 63

hi hi!
your lathe looks good!
whats included in the pitch box?
looks like a neumann "light" pitch box Very Happy

andybee

motorino · Joined: 24 Aug 2005 Posts: 212

Hi Andy!

have a lot of good things!! Laughing

stylus heating with adjust and iluminated meter

start, stop, lead in, lead out and mark, all with her "particular" speed

feed screw speed iluminated meter with pwm-vari-groove-kind (its a lighting psicodelic adapted, but works! with tc delay)

two switchs for manual or automatic work (starts turntable, positioning the cutterhead and go down slowly, when go finish stop the feed screw and lift up the cutterhead) im very happy

Merry Christmas!

flozki · Joined: 19 May 2006 Posts: 55 Location: switzerland

wow.wow.wow. !very very nice...you did a great job. i think this lathe found a perfect home...
about the rca head.no infos yet. there are a few stacks of datasheets and infos i have to check. but the head looks like a standard solution like presto head and many others. thanks for the pictures anyway.

cuttercollector · Joined: 11 Jun 2006 Posts: 286 Location: San Jose, CA

It looks like the one in my RCA portable. A lot of early ones of many brands just used a horseshoe magnet assembly. This looks like one of those. I know Gib, the West Tech guy here in the US lists a price to rebuild and remagnetize that general type of cutter. It would be very interesting to hear what kind of sound it would have, restored and used in a modern lathe. The amp it would have been driven by would probably just have had a capacitor to make a simple high pass filter to record the "standard curve" whatever that was, for 78s. One thing, some of those were 600 ohm and some "voice coil" impedance.

motorino · Joined: 24 Aug 2005 Posts: 212

thanks

yes flozki, and your feedback-turntable-servo-dc motor design works very good too

the cutterhead have 3,9 ohms, and the wire gauge its similar to a hi-fi loud speaker, i test with a pnp-npn amp with 60 wats ultra-A

for the recording riaa curve i use a vst pluging

this cutterhead have a "dark" sound Laughing

, original vintage sound (very interesting..), works ok with a lo cut at 35 hz and hi cut around 5 khz

for the test i use pink noise at -15dbs, 1 minute, i use a infrared termometer for check the drive coil and no go up same room temperature, i believe its very strong if put "good" the signal
that cutterhead use #362 transco stylus (thanks Janice)

now i go for made more test, very interesting cutterhead

tsullivan · Joined: 02 Jul 2006 Posts: 27

My guess is that cutter was probably designed to cut wax, not lacquer. RCA stuck with wax the longest, well into the 40's.

Tom

motorino · Joined: 24 Aug 2005 Posts: 212

thanks Tom Wink

rear the cutterhead look a number 66 next MFD, i believe its made in year 1966

but, what notable diferences about cutting wax (castor oil?) or lacquer ( nitrocellulose)? i believe wax its more soft, no? need minus power driving?

thanks!

Happy new year!

cuttercollector · Joined: 11 Jun 2006 Posts: 286 Location: San Jose, CA

My portable machine with a head that looks a lot like this was made in more like 1946. Your 1966 date is well after anyone was making heads like that. It is not a pro unit. Lacquer was the material of choice for instantaneous recordings not meant to be mastered and pressed.
RCA was using Westrex feedback "D spec" like everyone else for their prof. wax masters even before WWII. This is clearly viewable in the "Command Performance" movie available all over including archive.org.

tsullivan · Joined: 02 Jul 2006 Posts: 27

I've got that "Command Performance" movie on DVD. Several sellers on ebay sell it, along with a few other interesting movies, such as a tour of the Wurlitzer factory around 1948 showing the manufacture of the famous Wurlitzer 1015 jukebox. The RCA movie is a very good documentary showing how shellac records were made around 1938. No tape in use then, everything was cut directly to wax.

Towards the end of the movie, where they show a typical family listening to the records, they show one of RCA's "Magic Brain" record changers. Been looking for one of those for years. It played both sides of a stack of records. Since those were introduced just before WWII, very few were made.

Tom

motorino · Joined: 24 Aug 2005 Posts: 212

here the number 66 in the Rca cutterhead

Shot with

motorino · Joined: 24 Aug 2005 Posts: 212

Shot with Canon PowerShot A80 at 2007-08-10

some photos disappear, I put them again Very Happy

andybee · Joined: 14 Aug 2006 Posts: 63

well, very nice!
you need a perfect cutting head?:
http://lathetrolls.phpbbweb.com/viewtopic.php?t=458
Smile

motorino · Joined: 24 Aug 2005 Posts: 212

he he, i knows sc99, and vc200, her price new, and the o.p. price..you have a good offer? Wink

vitanola · Joined: 10 Sep 2008 Posts: 6

This cutting head was used =in several different applications, none really professional. It is essentially a slightly modified version of the phonograph pick up introduced on the 1929 Victor RE-45. This unit was used to embiss pre-grooved discs in the RCA-Victor "store recorder", and with a diamond "trailing point" it was used to make embossed raw aluminum reference recordings in thwe early 1930's. This recorder was also offered for a few years in the mid 1930's as the entry level recording head for use with instantaneous (acetate) discs.

motorino · Joined: 24 Aug 2005 Posts: 212

thank you very much for the explanation! a luxe! has experience with this? will be very well received

thank you very much again

emorritt · Joined: 09 Nov 2006 Posts: 67 Location: Louisiana

I have a couple of these RCA heads as well as several other "horseshoe" mono heads. Sound is OK for home recording, very "warm" in most cases. Don't know how the coils would behave with RIAA encoded signal - might be too much high and blow; never tried.

Had a portable lathe that used this head but gave it to my cousin...

Also had a overhead attachment (early version) for a 70D transcription turntable that used this head. Have a picture somewhere, will post later.

Most of the mono "horseshoe" heads do have a warm sound, mainly due to their design and the way they're damped - rubber rings on the armature and some have the top of the armature damped into a block of rubber. If the rubber parts haven't been replaced, the sound is awwwwfulllll... Mad