Mono Cartridge Question

Ortofon give the tip diameters of their mono cartridges with spherical tips as either 18μm, 25μm and 65μm for late mono, early mono and 78s respectively. I presume mil is US for thousandth of an inch. That would be called thou’ in the UK and possibly the rest of Europe where they’ve heard of an inch but mil is rather confusingly used for millimetres here.
 

Of the stereo cartridges I’ve used on mono disks the Proteus Ogura PA wasn’t very happy, the microridge of a Dynavector 17D3 nearly as bad but the Replicant 100 and Gyger S felt at home, barring the slight loss from the mono button, on both late and early mono LPs. The 18μm spherical on my Decca with a £350 phono stage had the replicant on my stereo SPU Royal N with an £8k phonostage beaten on late monos but was hopeless on early ones.

Lots of good advice here. My understanding is that a true mono cartridge can have two coils but that each coil is designed as an independent mono coil, one for the left channel and one for the right channel.

There are many cartridges who entered the mono cartridges market in the past twenty or so years like Miyajima and Hana but other designers have been offering mono designs for decades. DECCA/London, Ortofon SPU and EMT have been at it for a very long time.

Personally I’m still modifying my Thorens TD 160 and it is a dedicated mono table with an AT 33 Anniversary mono cartridge. After upgrading my tonearm, I’ll probably replace my AT 33 with an EMT mono.

So I recommend at least looking at the EMT. It is considered as being in the same league as the Miyajima Zero but it costs a bit less.

Also, you may benefit from reading an older post of mine regarding mono cartridges. Jonathan Carr shared some his insights about his Lyra mono designs.

Finally, the stylus size and the groove width is a very real thing. I can hear the differences myself though it isn’t drastic. Hana offers a shibata stylus on their mono cartridge for those who play both micro groove and stereo lathe cut mono pressings.

I find myself running out of patience with the new owners of the London Decca brand. Five weeks ago they promised to call their tech and ask if he knew how JW wired the cartridges for mono. Ten days ago I asked again if anything had been heard. Nothing since. So today:

Repeat send: still nothing? I don't want to be a pain. If the answer is no, please tell me and I'll run out and buy a mono cartridge.

 

Just let me know, and I'll still wish you well and be in touch next time my Reference or Jubilee needs a rebuild!

 

Chris

I have got to agree with Dave @intactaudio. I think a conical stylus is simply not appropriate for playing back ANY groove cut by a cutting stylus made in the last 75 years (and perhaps more). If the playback stylus is not a facsimile of the cutting stylus - or if it is misaligned - it will NOT take the same path through the groove as the path used to cut the groove in the first place.

This is NOT to say a conical stylus won’t sound good! I am only saying you are giving up information in the groove and adding distortion (including, but not limited to, some second order harmonic which could be pleasing, but certainly not accurate.)

I posted an animation on our website to show how we simulated in finite element analysis software a 25um conical stylus tracing a 10kHz groove at 60mm playing radius. You can clearly see the vertical excursion of the stylus on the right side. The left side shows that the basins of the undulations don’t even get touched by the stylus. The stylus kind of skips from peak to peak. This happens to a lesser degree all across the record surface and certainly at lower frequencies than 10kHz. We choose a high frequency for this animation so it would be easy to visualize. If this were a mis-aligned fine line contact stylus, it would have even MORE vertical excursion (in a perfectly horizontally modulated groove, mind you) but it would at least reach down into the basins all the way.

Now, if you have a mono cartridge with a conical stylus and that cartridge does NOT allow vertical freedom of the cantilever, what do you think is happening to your grooves over time??? Not good, IMO. Dave may have already alluded to this issue.

By the way, @intactaudio, your silvered auto-formers are unbelievably excellent. I’ve turned many people on to them! I’ll use nothing else!

Cheers,

J.R. Boisclair

@wallytools 

Hey JR... I agree 100%...  there is no chance of a conical tracing a purely lateral cut groove without adding a vertical component to the movement.  IF there is no vertical compliance something has got to give and it ain't going to be the diamond in the short term.  Many people who have moved from a conical to an advanced profile have noticed that many of their noisy original Blue Notes magically have a new lease on life.   

dave