2. analog
  3. 150194-1294

Mono Reissues and the Conical Stylus

Hi Folks,

Recently I started buying mono reissues from Speakers Corner, Impex, and have recently ordered a few from Analogphonic. They're all of the 'long haired' variety. In the process, I've come to discovery threads where posters claim that the newer mono reissue grooves are cut in a V (stereo) shape rather than the vintage U (mono) shape.
My AT 33 mono cartridge comes with a conical stylus and from what I can tell, so do the better mono cartridges, i.e. the Miyajima Zero Mono. This of course would then create an issue where it pertains to using a conical stylus in a V shaped groove.

Around November, I plan to purchase a Jelco tonearm for my modified Thorens TD 160 and after that, will be looking to upgrade to a higher end mono cartridge. However, I don't see that they're would be a viable solution to the stylus dilemma given that I will only have one tonearm. I do by the way own a collection of early mono records but would like to find a cartridge that better crosses over between my vintage pressings and my reissues. Any help is greatly appreciated. Thanks!
goofyfoot
goofyfoot OP
1,314 posts
 
Dave, are you saying that late 1940's to late 1950's mono records are cut with the same V shaped groove as stereo records?
intactaudio
293 posts
 
That is my understanding.  I just looked at a 1955 London ffrr  (Ted Heath ant the London Palladium) and the groove is a V.  The bottom does have a slight radius.  A stereo cutting stylus specified by Ortophon has a 3-4µm radius which would explain that but that is still a fraction of the radius of even the smallest conical.  

dave
goofyfoot OP
1,314 posts
 
Dave,

I'm thinking that your London LP should be a microgroove pressing. I suppose technically you're correct, that the shape of the groove is a V looking shape however that groove opening is wider than the later stereo cut grooves. In fact, the grooves on LP's started out wider and progressively got more narrow over time. When Columbia introduced their microgroove pressings, manufacturers complained about how narrow the grooves were in comparison to the earlier records (i.e. 78's)
As Lewm mentioned, the U shape description is just a vernacular term for specifying the difference in dimensions in order to clarify the point being made. Mono cartridge makers will use a nude conical stylus because of those earlier groove dimensions.
lewm
12,428 posts
 
Dave, You wrote, "My take is that if the coils remain oriented at a 45º angle to the record and then wired in series for mono then it is a stereo cartridge wired for mono and it doesn't matter if it if done internally or externally. If however the same parts are used for a mono cartridge and the coil is oriented so there is only pickup in the lateral plane, then it is a mono cartridge. In this case there would be only be windings for pickup in the lateral plane and the windings at 90º to that plane would not be used / wound."
That is also what I and many others have been saying here and elsewhere.  What I wondered about is whether from a purist standpoint, does the true mono cartridge offer us a level of performance in the mono mode that cannot be had via the bridged stereo approach?  I guess that if you use bridging, then cancellation would be imperfect to the degree that the two channels of the cartridge are not perfectly matched, which probably never happens.
intactaudio
293 posts
 
Goofyfoot,
the groove width of the London ffrr is about 2.5 mil which is above the max spec for microgroove. Since the groove is v shaped the width has little to do with whether a conical will properly trace it.   the only issue that can arise is a 1 mil conical can disengage from a microgroove but a 0.7mil conical will not run into any more issues with a 3.2mil groove than it will with a 2.2mil microgroove.  In fact a 0.7 mil playing records previously played with a 1 mil will often be much quieter since it traces a part of the groove that hasn’t been played.  
More to discover