The Courteous Vinyl Playback Discussion

[dlaloum]

@Angsty the ‘ability issue’ is talking about the limitations of the cottage industry ‘gurus’ who build ultra expensive decks with ‘cottage industry tech’.

And since when did Chinese engineers wait for patents to expire? Why haven’t they already done it?

Personally, I can’t see why one wouldn’t go for a good LT arm instead, if you want high end and performance.

Ideally, you would go for both... like the sony linear tracking biotracer

 

[Angsty]

I’m unclear on the math regarding pivoted tonearms. How much distortion is introduced by the tracking error found in pivoted tonearms? Let’s consider a 9 inch tonearm as the example.

I’m sure articles have been published on this, but I don’t have a ready reference.

 

[Balle Clorin]

Why not try Google….plenty on the subject, you may even find the BauER/Baerwald /Løfgren original papers

https://pearl-hifi.com/06_Lit_Archive/02_PEARL_Arch/Vol_16/Sec_53/Audio_Critic/1987_Audio_Critic_No_10.pdf

https://www.worldradiohistory .com/Archive-All-Audio/Archive-Audio/80s/Audio-1980-01.pdf

or this, scroll down for arm tracing distortion

Note on Record Specifications

 

[Bob from Florida]

I’m unclear on the math regarding pivoted tonearms. How much distortion is introduced by the tracking error found in pivoted tonearms? Let’s consider a 9 inch tonearm as the example.

I’m sure articles have been published on this, but I don’t have a ready reference.

Short version is all geometries are compromises. Overhang changes where your lower and higher distortion exists around the 2 null points. If most of your records stop well short of the label, you can pick an overhang that yields lower distortion over the majority of the record - at the expense of higher last track distortion if that track ends close to the label. Pick your "overhang" and be happy. For maximum "anal retentiveness" get multiple identical cartridges and head-shells at different overhangs to use with different inner radius LP's.

 

[Angsty]

Thanks, Bob. I have seen publication of specs and graphs that show the maximum tracking error in degrees but I have yet to see something that converts that into percentages of THD. Well, actually, the alignment curves do show distortion related to groove radius, but how does that change with tonearm length?

What I really want to know is how big is the tonearm length contribution to tracking distortion compared to the frequency-dependent distortion inherent in all cartridges. If I consult the various overhang graphs, it appears to be small.

 

[Bob from Florida]

Thanks, Bob. I have seen publication of specs and graphs that show the maximum tracking error in degrees but I have yet to see something that converts that into percentages of THD. Well, actually, the alignment curves do show distortion related to groove radius, but how does that change with tonearm length?

What I really want to know is how big is the tonearm length contribution to tracking distortion compared to the frequency-dependent distortion inherent in all cartridges. If I consult the various overhang graphs, it appears to be small.

Longer arms should have lower error due to a "better" arc. However, the length affects resonance, effective mass, rigidity, etc.. There is the practical aspect also - do you have room for a turntable with a 16 inch arm? My new Sorane arm has an effective length of 9.4 inches. It works fine. I think the reason we see the majority of arms around 9-10 inches is it's a reasonable compromise.
As far as distortion goes, I suggest to simply minimize where you can. Pick a quiet reasonably quiet, accurate speed, with below perception wow and flutter table. Pick an arm that is a good match to your cartridge/stylus choice. Do a decent alignment/setup and get a record cleaning machine. Stick to a budget as you can talk yourself into some expensive gear....

 

[Balle Clorin]

The formula is in the links I gave. if you cannot find it , ask you mother..

 

[undeakyetonde]

Most of the servo linear trackers, use error correction to move the arm base linearly - however the arm itself, is typically still a pivoted arm... but the angles of pivot needed are tightly limited by the fact that the base is shifting - so the tracking error due to pivoting is reduced to a near optimal level... a level of tracking error that a "normal" arm can only achieve at one point while traveling across the record surface... the linear tracker achieves that right across the surface of the record.

Hence the servo doesn't have to be spot on... it just has to be "close enough".

Yes, the question is whether it is "close enough", does a servo linear tracker really deliver on its promise, and how do we know/check that

Are the corrective motions small enough? What is the realistic upper bound on tracking angle error given a well-calibrated tonearm/turntable? Again, how exactly do we know that?

 

[Bob from Florida]

Yes, the question is whether it is "close enough", does a servo linear tracker really deliver on its promise, and how do we know/check that

Are the corrective motions small enough? What is the realistic upper bound on tracking angle error given a well-calibrated tonearm/turntable? Again, how exactly do we know that?

You could purchase a table capable of 2 tonearms. A linear and pivot arm. Put the same model cartridge on each arm. Get a test record, capture the sweep tracks from each arm and utilize the cartridge measurement script to compare frequency response and harmonic distortion. That should give you some hard data to analyze.

 

[Balle Clorin]

The tangential arm may have an error of 0.3 degree and your cart has a tolerance of plus minus 3-5 degrees. …and a pivot arm 2 degrees,,,The distortion is half of that, and the vinyl itself has 0.5-10% distortion.. if you want perfection buy a CD

 

[undeakyetonde]

You could purchase a table capable of 2 tonearms. A linear and pivot arm. Put the same model cartridge on each arm. Get a test record, capture the sweep tracks from each arm and utilize the cartridge measurement script to compare frequency response and harmonic distortion. That should give you some hard data to analyze.

I'm sure I personally could do all of that, spending a ton of money on an endeavour that has moderate chance giving of a reliable result

What I'm curious about is how does a manufacturer know? They didn't get these 0.3 or 0.1 degree specs out of nowhere, did they?
There should be specific characteristics of the sensors and ICs and feedback systems etc etc that allow them (and maybe us?) to estimate avg/std of the tracking error, upper/lower bounds?

The tangential arm may have an error of 0.3 degree and your cart has a tolerance of plus minus 3-5 degrees. …and a pivot arm 2 degrees,,,The distortion is half of that, and the vinyl itself has 0.5-10% distortion.. if you want perfection buy a CD

The goal is to try to reduce unnecessary distortion at step of the signal transmission. For example, to digitise a recording that isn't available on CD or as a decent web release. Finding a cartridge with properly mounted stylus is a separate issue.

Is that THD rel. to specific tone? THD integrated over the whole audible range?

Why would you feel the need to point to digital audio in a vinyl playback thread during discussion of an aspect of vinyl playback

 

[JP]

What I'm curious about is how does a manufacturer know? They didn't get these 0.3 or 0.1 degree specs out of nowhere, did they?
There should be specific characteristics of the sensors and ICs and feedback systems etc etc that allow them (and maybe us?) to estimate avg/std of the tracking error, upper/lower bounds?

It's just math, and for the ideal case wouldn't be too difficult if the min/max angle and sled advancement distance, etc. of the arm is known.

 

[Bob from Florida]

I'm sure I personally could do all of that, spending a ton of money on an endeavour that has moderate chance giving of a reliable result

What I'm curious about is how does a manufacturer know? They didn't get these 0.3 or 0.1 degree specs out of nowhere, did they?
There should be specific characteristics of the sensors and ICs and feedback systems etc etc that allow them (and maybe us?) to estimate avg/std of the tracking error, upper/lower bounds?


The goal is to try to reduce unnecessary distortion at step of the signal transmission. For example, to digitise a recording that isn't available on CD or as a decent web release. Finding a cartridge with properly mounted stylus is a separate issue.

Is that THD rel. to specific tone? THD integrated over the whole audible range?

Why would you feel the need to point to digital audio in a vinyl playback thread during discussion of an aspect of vinyl playback

It seems like some answers have been given, however, you don't seem to accept the answers. A lot of free knowledge is given at this site. However, if that is not sufficient, then paying for papers behind a paywall or testing things yourself becomes an option. Knowledge is not necessarily "free". Usually there is a cost - could be time invested and/or money spent.

 

[egellings]

Did Mark Levinson come out with an electronically damped tone arm quite a long time ago, but it never became popular despite its fine performance?

 

[dlaloum]

Yes, the question is whether it is "close enough", does a servo linear tracker really deliver on its promise, and how do we know/check that

Are the corrective motions small enough? What is the realistic upper bound on tracking angle error given a well-calibrated tonearm/turntable? Again, how exactly do we know that?

Measured results from the heyday of LT's show results on a par with the best pivoted TT's... and maintaining performance across the length of the records... Inner track distortion was then limited by the cutter (yes the inner track is lower quality!) rather than the arm...

But ultimately other factors will impact just as much if not more - cartridge compliance to arm mass matching can have a greater impact than arm geometry...try a 2g VTF MC in a 4g LT arm.... the results are poor to say the least! - and it was recommended to me by a "reputable" audio retailer/consultant.... at the time I knew nothing about compliance/mass matching... and it put me off vinyl for some years, until I came back to it, and swapped out the low compliance MC for a high compliance MM - and the magic came back!

Revox Linear tracker - 4g arm, designed as an ultra short, uni-pivot, on a servo driven tracking system, with damping grease at the pivot point.

At an audio show in the early 80's some of the engineers involved in designing/making the record cutting lathes, observed that it rides exactly the way the lathe does... which is ultimately the objective for any TT!

 

[Anton D]

Awesome!

Thanks for that post!