Mono Cartridge Question

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

The AT 33 mono has a 0.65 conical stylus with vertical compliance which is why anyone can play a stereo record with this mono cartridge. I had a Grado mono with elliptical stylus and without vertical compliance and it destroyed any stereo record in came into contact with.

@goofyfoot 

playing a stereo record with a "no vertical compliance"  mono cart does indeed tend to end badly.  It is important to understand why this is the case.  In a stereo record, the information common to both channels is cut in the lateral plane and the information unique to each channel (stereo) is cut in the vertical plane.  Playing this back with a generator with coils oriented at 45° to the record surface presents the complete stereo image.  It is the vertical (stereo) info that takes the hit when played with mono cartridge with no vertical compliance.  

As JR has pointed out playing a high frequency mono signal with a conical profile also creates a vertical component so the same thing happens but to a lesser degree.  The results of this are not as dramatic as the results of your mono Grado on a stereo cut but the effect still happens.  Over time, this is not a great way to treat your precious early original mono recordings.

The case of your grado having an elliptical profile  (or any other advanced profile) does not make things instantly better.  The problem here is not the shape of the profile but the lack of vertical compliance.    I actually believe that if not properly aligned, once the advanced profile is introduced to a situation with no vertical compliance, things can be even more damaging than a conical even on mono cut records.

dave