My cartridge’s stylus cantilever skews when dropped to record

[Croc999]

Hello All,
My turnable was setup by the dealer and sounds good.

But today i took a look on the stylus with a lupe for the first time.
With the record stopped when i drop the needle i see that cantilever gets skewed to the inside of the record.
I meat it looks kinda bent.
When tonarm is up the cantilever looks straight.
This this true on non moving record with zero antiskating.
When i add antiskating the cantilever skews inside even more. Much more actually.
What can cause this and what alignment/adjustment should fix it?

JR from Wallytools talks in one of his videos about "tonarm horizontal force" - is that it?

The tonarm BTW is Nottingham Ace Space - which is a kind of unipivot:

Nottingham Analogue Ace Space Tonearm

Nottingham Analogue Ace Space Tonearm The perfect partner to a Nottingham Analogue deck All Nottingham arms are a unipivot design. Unipivots are usually designed with the pivot sitting in a silicone bath. The problem with this design is that the silicone bath takes quite a while to settle down...

www.analogueseduction.net

 

[Solypsa]

If this issue is easy to capture with a camera, a picture might be useful.

When playing a record does the cantilever look skewed still? Should be easy to see without a loup.

 

[tmallin]

What you describe might be caused by improper tonearm azimuth adjustment. This is especially so with a unipivot-type arm which is not held in horizontal aligment by a set of four gimbal bearing common with other types of tonearms. A unipivot arm is free to rotate in the horizontal axis. Adjust the tonearm so that the top of the headshell is exactly horizontal with respect to the platter when the tonearm is resting on a stationary record.

If the tonearm is not horizontal--that is, if the tonearm azimuth is improperly adjusted--the angle between the headshell and the platter/record will tend to make the stylus deflect or bend either toward the center of the record or toward the outside edge of the record.

Another cause could be that your antiskating mechanism is not truly disengaged even when you think it is. The mechanism's springs may be out of adjustment or if it uses a combination of springs and hanging weights, the weights may still be applying some antiskating torque even if you adjust the antiskating to zero.

 

[Shuggie]

If the headshell is level, and the cantilever looks OK but only skews to one side when lowered onto the record, even with anti-skate disengaged, then I suspect that there is something wrong with the cartridge suspension, and it probably needs to be returned to the retailer.

Nottingham Analogue arms are unipivot, but 'captured' in a way that means there's virtually no wobble. Also, the anti-skate mechanism consists of a simple weighted rod that acts on a bar protruding from the right side of the 'bearing' housing, so no springs and all parts totally visible. Pretty obvious when it's engaged or not. In my experience pretty heroic levels of anti-skating force are needed to induce more than a tiny degree of lateral cantilever skew.

@Croc999 Is the cartridge Moving Magnet or Moving Coil? A video showing the deflection as it occurs would be helpful.

 

[Croc999]

Thank you all for your input on this !!!
This is an interesting issue - let's see if we can get to bottom of it...

As Shuggie said:
- the Nottingham tonearm has very little side to side movement range
- its antiskating is mechanical lever with weight - so when it's OFF it's OFF

The azimuth optically looks ~OK (i think).





Some videos with static/dynamic and antiskating OFF/ON

I also rechecked and readjusted leveling (seems no changes to the issue) and WTF (was OK).
Also played with tonearm cable to make sure it's not twisted (as JR suggests in his video), and even did a half twist to the opposite direction....

 

[mtemur]

Use it with anti-skating. It looks best like that. There can be many reasons for this but it’s hard to figure out which without actually putting hands on. If you have AM software trying zenith alignment is the logical thing to do.

Another thing you can do is checking side force. IOT do that;
- first zero VTF, tonearm should float,
- zero anti skating
- place VTF scale as shown in the picture and turn it on afterwards not before.
- check side force of tonearm by placing tonearm to the scale just like the one in the picture
- set anti skating and check again.

 

[JackD201]

There you go. Dynamic azimuth. When I was starting out with "serious" analog. I had a JMW arm on an Aries. Cart at the time was I believe a CA Strad. This was the mid 2000s or so and the talk in our local forums was that CA carts in general sounded edgy. It was a pain in the butt with the weird way VPI would make you adjust azimuth with that off center counterweight and antiskate by twisting the wires? Dunno, never tried twisting the wires as I was too afraid to break them with my sausage fingers. Anywayyyyyy...... a friend came in and suggested I go for dynamic rather than static since I had a unipivot arm. I never quite got it perfectly but the improvement was easily noticeably. This prompted me to upgrade to a second hand Phantom 1 on a second hand HRX, it was a snap to do repeatably with the Graham. That pretty much killed the edgy tag on CA carts as well as other "mosquito proboscis" cantilevered carts. Looks like your dealer knew this and did right by you.

 

[Shuggie]

Thank you all for your input on this !!!
This is an interesting issue - let's see if we can get to bottom of it...

Some videos with static/dynamic and antiskating OFF/ON

I also rechecked and readjusted leveling (seems no changes to the issue) and WTF (was OK).
Also played with tonearm cable to make sure it's not twisted (as JR suggests in his video), and even did a half twist to the opposite direction....

I wonder if the arm's lift platform is complicating things in your videos, because in the first one the cantilever seems to be deflected and then settles pretty much immediately back more or less where it should be.

Can you do another video, dynamic, no anti-skate force but running on for a little while after the tip has settled?

 

[Croc999]

Few more tests today.
Since @mtemur asked to do a test with electronic scale - i had to make mine working.
i bought one exactly like this long time ago but it came without batteries.
a shop nearest to me didn't have this AG12 type and didn't bother to look further.
So today i went to 5 shops - none of them have those.
But i saw that LR44 kinda fit - so i've used them for now.

Anyway.....
First obvious test was to recheck WTF.
Instead of 2.4 i've got 3.6.
Ooops...
How the hell WTF had changed???
Since the dealer had set it ~18 months ago i never touched it (he had used a fancy ORB digital scale)

To be sure I rechecked the scale with 5gr weight - it's OK.
I created a platform to be closer to real stylus height while on the record - same result.
So i readjusted to 2.4 and this is how it looks now:

It still looks to me a bit skewed - isn't it?

Couldn't do @mtemur 's test - the scale went crazy when i've putted it on the side....
But did test without measuring - i balanced the tonearm in a zero height state and with NO antiskating - this how it looked:

The leveling was readjusted yesterday with 3 different levels (each shows a bit different but variations are small).

BTW when i was done and went to set 2.4 VTF i recalled that it should be set with NO antiskating - am i right?
So it's 2.4gr and with antiskating ON it shows 2.35gr.

 

[mtemur]

First obvious test was to recheck WTF.
Instead of 2.4 i've got 3.6.
Ooops...
How the hell WTF had changed???
Since the dealer had set it ~18 months ago i never touched it (he had used a fancy ORB digital scale)

That’s perfectly normal but not ok. It’s a common problem with uni-pivots. When you lock tonearm at rest position or because of another problem uni-pivot moves from it’s position. This changes the balance of the tonearm and inescapably changes VTF. Sometimes anti-skating or azimuth mechanisms pull pivot from it’s position. Grahams have strong magnets for azimuth causing this VTF problem.

Couldn't do @mtemur 's test - the scale went crazy when i've putted it on the side....

Try turning the scale on only after putting it on it’s side, not before.

BTW when i was done and went to set 2.4 VTF i recalled that it should be set with NO antiskating - am i right?
So it's 2.4gr and with antiskating ON it shows 2.35gr.

VTF may change because of anti-skating on uni-pivots. Another issue but not a big deal. Real VTF of your tonearm is 2.35g. You should set VTF anti-skating engaged.

In the first video I don’t see a big problem, it looks ok to me. In the second video your tonearm has internal forces helping anti-skating but it doesn’t look too strong. If you can manage to get a reading with scale I assume it will be around 0.05-0.1g without anti-skating engaged. It should be ok. Final value should be 0.28g for 2.4g VTF.

 

[Croc999]

Update - got it measured few days ago - side force shows 0.29gr.
Antiskating is disengaged during this measurement.



I'm not worried because next week my new Kuzma setup is arriving.

But still i'm curious what makes this arm to behave like this...