Custom Lenco L75 vs Technics 1200's

I await Dover's response but I too have thought about his contention in the belief there must be some truth to it. What I can "see" is that if you set az on a tonearm that does not have offset bearings to match headshell offset, there will be a small change in az when the cartridge encounters a warp.  Something like this also happens when you twist the cartridge in the headshell in order to conform to an alignment algorithm that is not what the tonearm was designed for. By twisting, the cantilever horizontal angle (not the vertical angle) with respect to the arm wand no longer mimics the bearing offset horizontal angle. In one case of doing this, it seemed to me that this caused audible distortion, years ago.

@billstevenson 

@lewm 

Gentlemen, I have made a video for you to demonstrate the issue with tonearms with non offset vertical bearings - 

https://www.youtube.com/shorts/vpM0qcHZYnA

Dover

@dover 

When adjusting is your stylus touching the record? Also is this happening with the arm you’re using or will a Technics or the Denon arm act the same way?

Also when you adjust the VTA are you supposed to make the arm level with cart. and the record you're using. So does this happen when everything is level?

It’s hard to believe when Technics or Denon make adjustable VTA this would happen. 

Also where do you buy the small bubble level in the video?

Thank you

@romad 

When adjusting is your stylus touching the record

Yes, the stylus is on the record, and when VTA is adjusted you can see the cartridge rotates sideways as the VTA is raised.

Also is this happening with the arm you’re using or will a Technics or the Denon arm act the same way

This will happen for any arm that has non offset bearings. From what I can see the Denon has non offset vertical bearings, and if that is the case it should happen. The Technics arms have offset vertical bearings that match the headshell offset and therefore when VTA is adjusted on the Technics arms the cartridge remains vertical.

Also when you adjust the VTA are you supposed to make the arm level with cart. and the record you’re using. So does this happen when everything is level?

Starting with the arm level is a guide only. What you are trying to do is replicate the cutting angle of the record with the stylus angle (VTA). If the stylus angle matches the cutting angle when the arm is level then that is the correct position.

To compound the issue records are often cut using a range of cutting angles - standards are a bit rough. That’s why some folk like to be able to adjust VTA easily, and repeatedly. 

Secondly, you want to be able to adjust the tonearm easily for different record thicknesses. In theory if you are adjusting for record thickness, then the VTA does not change and there is no issue.

It’s hard to believe when Technics or Denon make adjustable VTA this would happen. 

As I said, Technics has built an arm with offset vertical bearings so there is no problem. Denon like many others appears to have built an arm with non offset bearings.

It gets far worse - Swedish Analog Technologies builds tonearms close to $100,000  that have non offset bearings which has the same problem. What is puzzling is that their first tonearms had offset vertical bearings, but their new "improved" arms don’t. I believe that they probably changed the design for ease of manufacture.

All the Origin Live tone arms have the same non offset problem - and their arms range up to UK$50,000.

Examples of tonearms that have offset bearings are Linn, SME V, Kuzma, Rega

For my own system I no longer use the vintage SME 3010R in the video for the reasons explained.

I am now running a Sumiko MDC800 on that turntable. The Sumiko MDC800 has offset vertical bearings so VTA can be adjusted without having to address the azimuth problem.

The small bubble level in the video came supplied with the Van Den Hul Colibri XGW that is mounted in the headshell in the video. You should be able to find small bubble levels for this purpose from Hifi Accessories stores.

@dover Thank you for taking the time to make the video to verify what you are talking about.  In fact your verbal explanation was clear to me and as I re-verified yesterday, the Denon in my possession does not display this behavior.  When the VTA is adjusted, the entire mounting plate, arm, bearings and all is raised and lowered as a piece.  Azimuth is not affected on this turntable due to adjustments in VTA.  I checked this using several methods and in several positions including using a bubble indicator.  I also verified that the distortion level remained unchanged using AnalogMagic, a measurement that is repeatable and verifiable.