[78-L] Groove width, was Edge Bite

[J. E. Knox]

Greetings from FixitLand!

Steven C. Barr wrote:

> Keep in mind we are talking about grooves that are .003" wide...so
> even the width of one coat of "Super Glue" adds about .0005" or
> half a groove width...!

Aside from the math error here, which has been addressed previously...

Those grooves aren't actually .003" wide. The so-called "standard" . 
003" dimension is the *radius* of the stylus tip (thus, if the tip  
were a ball, it would be .006" diameter). Groove width and depth  
standards changed throughout the 78-rpm era, but take Harry Sooy's  
1925 specifications (quoted here from his memoirs) as an example:

"May 5th, 1925: After using a groove of a 'u' for many years, .002 D  
and .006 W, we made a change in shape somewhat, making the standard  
size groove .002 D [and] .007 W."

That's why early Victor electrics sound "swishy" when played with a  
Shure 2.6-mil stock stylus (like N75-3).

Take care,


Joe
--
It's my cats' world. I'm just here to fill their food dish.