Cartridge/Tonearm Theory Question

snap, crackle and pop
WHAMMO_63
member
member
Posts: 27
Joined: 29 May 2017 16:52

Cartridge/Tonearm Theory Question

Post by WHAMMO_63 » 12 Jun 2019 17:15

Been thinking just a bit about cartridge alignment, and it seems to me that if one could simply replicate the positioning of the cutting needle on the lathe when a record is mastered, that cartridge alignment would be achieved. Could someone here explain the difficulties involved in achieving this? Or would the Steve Hoffman forums be a better place to ask?

Now we had a lathe at the recording studio where I worked in the 80s to make acetates, but that was a pivoting tonearm IIRC. The high-end mastering lathes are all linear I believe.

simonineaston
senior member
senior member
Great Britain
Posts: 285
Joined: 02 Feb 2004 15:20
Location: Bristol, UK

Re: Cartridge/Tonearm Theory Question

Post by simonineaston » 12 Jun 2019 17:31

WHAMMO wrote:if one could simply replicate the positioning...
I don't think it's that simple. If it were, we'd all be in aural seventh heaven! Just for a start, each cartridge /arm combination has got different physical & electrical properties - and that's even before you consider the tools available to make sure you can adjust the physical variables suitably... some are subtle and capable of giving accurate results and some are not. And, although I don't know much about vinyl disc cutters, I imagine they all differ, company to company, enough to make their individual attributes rather opaque!
And when you take into account the evidence from the good folk on this very forum, when they often describe making changes that at first reading may seem counter-intuitive, but turn out to suit the ears of the beholder very well, you can but conclude that what works is very often not quite what you think it should be...

WHAMMO_63
member
member
Posts: 27
Joined: 29 May 2017 16:52

Re: Cartridge/Tonearm Theory Question

Post by WHAMMO_63 » 12 Jun 2019 18:16

simonineaston wrote:
12 Jun 2019 17:31
WHAMMO wrote:if one could simply replicate the positioning...
I don't think it's that simple. If it were, we'd all be in aural seventh heaven! Just for a start, each cartridge /arm combination has got different physical & electrical properties - and that's even before you consider the tools available to make sure you can adjust the physical variables suitably... some are subtle and capable of giving accurate results and some are not. And, although I don't know much about vinyl disc cutters, I imagine they all differ, company to company, enough to make their individual attributes rather opaque!
And when you take into account the evidence from the good folk on this very forum, when they often describe making changes that at first reading may seem counter-intuitive, but turn out to suit the ears of the beholder very well, you can but conclude that what works is very often not quite what you think it should be...
All very good points Simon. I suppose that 'simply' is a misnomer, but that is what I think the goal really is.

Just thinking out loud, I wonder if a groove spacing standard would help. Say you buy a record, and it has a number that is read by the stylus telling the onboard computer the groove spacing for that particular recording. Hmm...

EDIT: Yes, I know I'm about 75 years too late LOL :roll:

billshurv
long player
long player
Posts: 2108
Joined: 16 Oct 2014 15:38

Re: Cartridge/Tonearm Theory Question

Post by billshurv » 12 Jun 2019 22:33

Linear tonearms rule for getting closest to the cutting lathe. However that only gets to the point where the fun starts...

WHAMMO_63
member
member
Posts: 27
Joined: 29 May 2017 16:52

Re: Cartridge/Tonearm Theory Question

Post by WHAMMO_63 » 12 Jun 2019 23:35

billshurv wrote:
12 Jun 2019 22:33
Linear tonearms rule for getting closest to the cutting lathe. However that only gets to the point where the fun starts...
Exactly! But I was thinking there must be a setting for groove spacing on the lathe? Of course, linear tonearms are by design very good at tracking an unknown groove spacing.

billshurv
long player
long player
Posts: 2108
Joined: 16 Oct 2014 15:38

Re: Cartridge/Tonearm Theory Question

Post by billshurv » 12 Jun 2019 23:38

nope, the computer adjusts that on the fly based on peak levels adding a digital delay in the signal... At least for an awful lot of vinyl. GZ actually simulate the cut before they start to calculate groove spacing, but other than for direct cut stuff it varies. (Phil will possibly come along and correct me here).

chiz
senior member
senior member
Great Britain
Posts: 793
Joined: 16 Oct 2009 23:05
Location: London

Re: Cartridge/Tonearm Theory Question

Post by chiz » 12 Jun 2019 23:39

Groove spacing usually varies with modulation.
Extreme example:
telarc1812a.jpg
(125.72 KiB) Downloaded 110 times
telarc1812c.jpg
(135.2 KiB) Downloaded 103 times
Last edited by chiz on 12 Jun 2019 23:59, edited 1 time in total.

billshurv
long player
long player
Posts: 2108
Joined: 16 Oct 2014 15:38

Re: Cartridge/Tonearm Theory Question

Post by billshurv » 12 Jun 2019 23:41

Telarc 1812 unless I am mistaken :)

chiz
senior member
senior member
Great Britain
Posts: 793
Joined: 16 Oct 2009 23:05
Location: London

Re: Cartridge/Tonearm Theory Question

Post by chiz » 12 Jun 2019 23:51

billshurv wrote:
12 Jun 2019 23:41
Telarc 1812 unless I am mistaken :)
Well spotted sir :)

billshurv
long player
long player
Posts: 2108
Joined: 16 Oct 2014 15:38

Re: Cartridge/Tonearm Theory Question

Post by billshurv » 12 Jun 2019 23:52

I'm sad like that :)

pivot
long player
long player
United States of America
Posts: 4830
Joined: 27 Dec 2002 15:31
Location: Albany, NY USA
Contact:

Re: Cartridge/Tonearm Theory Question

Post by pivot » 13 Jun 2019 02:06

If you want perfect alignment you need a linear tracking tonearm.

Getting an arm that really tracks tangentially is easier said then done. The best are expensive.

Not a new concept. In the end you have to decide if it is worth the fuss, cost, and complexity.

lenjack
long player
long player
Posts: 1381
Joined: 23 Jun 2017 02:11
Location: Liverpool,PA

Re: Cartridge/Tonearm Theory Question

Post by lenjack » 13 Jun 2019 02:28

That legendary Telarc 1812 is from the A11 first pressing, which wrecks havoc on almost all arm/cartridge combos.

WHAMMO_63
member
member
Posts: 27
Joined: 29 May 2017 16:52

Re: Cartridge/Tonearm Theory Question

Post by WHAMMO_63 » 13 Jun 2019 04:02

So, the cannon then?

We used to play one of the first DDD recordings of that in the studio. Even with all the soundproofing, it sounded like a bomb went off in the building 😂

Solist
senior member
senior member
Slovenia
Posts: 598
Joined: 08 May 2017 18:49
Location: Ljubljana

Re: Cartridge/Tonearm Theory Question

Post by Solist » 13 Jun 2019 10:17

The problems with linear tracking tonearms is that you need a different type of mechanism to move the tonearm across the record. And ideally if you think about it, good tonearms are those which are basically invisible, or have no effect whatsoever on the movement of the cartridge.

On a traditional tonearm this is "easily" achieved since pivoted designs are simple designs. The trade off with this tonearms is that they dont read parallel as the linear trackers. Protractors usually have 2 points, and there is where the distortion should be the lowest (ideally 0, but its hard to set the needle perfectly). You can pick longer tonearms 11inch, which if you imagine will have a lower tracking distortion. If you were to draw a bigger circle which imitates the path of the needle, you can see that the bigger the circle the flatter the curve is. The problem with longer tonearms is that they like to resonate, so some clever damping and tube construction is desired to minimize those resonances. Short tonearms have a bigger tracking error, but are much less sensitive to vibrations. Most manufacturers went with 9inch tonearms in the past, since its a compromise of those 2 worlds.

Now, you can choose different protractors for these pivoted tonearms which will distribute the distortion in a different way across the record, if your tonearm geometry allows it. If you have a short 8 inch tonearm, or if you listen to a lot of classical music, stevenson can be a good choice, since it prioritizes inner grooves to minimize the distortion. Shorter tonearms have more difficulty tracking the inner grooves, and with a lot of classical music there are those big loud crescendos at the end of a record which can cause distortion. The other popular option is Lofgren A, which will distribute the distortion more evenly across the whole record. You can also try to make your own protractor to see how different values have an effect on the tracking error and distortion.

In the library section there is a nice tool for this kind of things:

https://www.vinylengine.com/tonearm_ali ... or_pro.php

And then you have linear tracking tonearms, which ideally have no tracking error. The problem with this tonearms is that they require a different type of mechanism to move the tonearms freely across the record. The last thing you want is the needle to drag the whole mechanism behind it. This will impede the ability of the needle to track the grooves properly. Some use air bearings for this purpose, but air bearings needs to be refilled and they are prone to leaking. Some use motorized mechanisms. There are even more problems. The mechanism needs to be perfectly in sync, otherwise you end up with a loss of information. The complexity is much higher in comparison to the pivoted tonearms, so the price is higher, and the demand is low.

I think that overall pivoted tonearms if done properly are good enough or even better than most of the linear tracking tonearms, the price is usually lower which is a bonus (more money for records), and are less prone to failures on the long run.

This is my 2c. Would love to hear more opinions about this.

cafe latte
vinyl addict
vinyl addict
Australia
Posts: 10836
Joined: 11 Oct 2009 04:27
Location: Cattle property near Ravenshoe Qld Australia

Re: Cartridge/Tonearm Theory Question

Post by cafe latte » 13 Jun 2019 11:32

pivot wrote:
13 Jun 2019 02:06
If you want perfect alignment you need a linear tracking tonearm.

Getting an arm that really tracks tangentially is easier said then done. The best are expensive.

Not a new concept. In the end you have to decide if it is worth the fuss, cost, and complexity.
I have an Eminent Technology air arm and they are stunning. How far behind is a 9 inch arm of same quality? No difference IMO. Love the Eminent, but linear have their own issues, one plane us locked up, it moves left and right, but with whole arm. Million ways to do this and non perfect.
Chris

Post Reply