[Phono-L] Coin machine or jukebox needles?

[Greg Bogantz]

    Osmium tipped needles were a transitional style.  They were the cheapest 
"permanent" needle typically marketed in the late 1930s thru the '50s.  The 
more expensive varieties of "permanent" needles were sapphire or ruby and 
the most expensive were diamond.  People were using record changers and 
didn't want to mess around with changing steel needles all the time, so 
these styles became popular.  The problem with all of these needles in that 
time period is that the pickups tracked at too high a force for any of them 
to be optimal with regard to record wear.  The magnetic and crystal pickups 
of that period typically tracked at between 30 and 80 grams.  Although 
that's less than the 80 to 150 grams of the earlier acoustic reproducer 
period, it's still just too high for any of these hard needles.  They were 
especially deadly when used with the early vinyl 78s that were beginning to 
appear after WWII.  The proper technology for high tracking forces was the 
steel or tungsten wire needle when used with shellac records that contained 
abrasive fillers that were intended to quickly wear the needle into 
conformance with the groove shape.  But, of course, the steel needles needed 
to be changed with every record side or two.  Tungsten WIRE shaped needles 
are superior to the osmium tipped needles because the cylindrical wire shape 
retains the same cross-sectional area during the entire lifetime of the 
needle.  The osmium needles were tapered and as they wore they got a bigger 
cross section.  This is fine until the cross section gets too big to fit 
into the groove width which happens after just a few records are played. 
Then the needle forms shoulders that ride outside the groove and on the land 
of the record.  This lifts the needle out of close contact with the groove 
walls which leads to mistracking, distortion, and high record wear.  These 
hard needles, especially the sapphire and diamond ones don't wear down 
quickly, and instead wear the records.  These needles that were typical in 
this time period are the main reason that records that have survived from 
the '30s thru the '50s look worn and sound more distorted and worn than 
records that have survived from the teens and '20s and that were played 
properly with steel or tungsten wire needles.  The use of these hard needles 
only became proper when pickup tracking forces were reduced to 10 grams or 
less in the 1950s.  I don't feel comfortable using them even above about 5 
grams.  Tracking forces of 1 to 2 grams became commonplace in the early 
1960s, and jewel-tipped needles are perfectly satisfactory when used in 
these pickups.

    The bottom line is, I would NOT recommend using hard needles in any 
pickup tracking at more than 10 grams if you want to preserve your records. 
When new, these needles will sound good for a while.  But they will be 
grinding the bejeezus out of your records if you are tracking them at 30 
grams or more.  If you have a jukebox or record changer that operates at 
high tracking force, use tungsten wire needles.  Or change the pickup (and 
tonearm if necessary) to allow tracking forces below 10 grams if you want to 
use jewel-tipped needles.  Osmium would also work in this application, but 
it will wear out after 20 sides or so, even at this tracking force.  Osmium 
is just a bad idea for just about any application.

Greg Bogantz


----- Original Message ----- 
From: "Chris Kocsis" <chrisk33 at cox.net>
To: <phono-l at oldcrank.org>
Sent: Wednesday, March 10, 2010 8:47 PM
Subject: [Phono-L] Coin machine or jukebox needles?


> Can anyone give me the lowdown on jukebox needles?  I bought some new old 
> stock Cole's coin machine needles with osmium tips.  The package says the 
> needle lasts many plays and doesn't have to be rotated.  I'm also curious 
> about the shape of the needle.  A couple of millimeters up from the point, 
> the metal is flattened into a pointed oval like a cobra head and then 
> resumes being cylindrical.  What is that for?
>
> Osmium is nearly as hard as tungsten and I've seen some references to 
> people cutting their own needles from tungsten wire and forming the point 
> by rubbing the cut end in a record groove while rotating it (which seems 
> astonishing).
>
> Is such hardness a good idea in a needle, or does it cause excessive 
> record wear?
> If these jukebox needles are safe to use, how do I tell when it's time to 
> change one?
>
> Best regards,
>
> Chris
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