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Understanding tonearm/cartridge matching

the_nines

the_nines

Lunatic Member
I've been reading a bit through the "search" option of AK on trying to understand the concept of matching a cartridge to a tonearm. I see that there are quite a few members (like me) who want to understand the main principle behind all this "matching" concept.

I also did some reading on the net and came across this little article which I would like to share with those of us who would like a starting point in understanding what all this tonearm/cartridge thing is all about.

The link:

http://www.gcaudio.com/resources/howtos/tonearmcartridge.html

Hope this sheds some light.
 
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Yes, that article certainly covers the basics. And now for the still unanswered questions:

1. There seem to be discrepencies regarding compliance figures, static vs. dynamic, some reported at 100Hz instead of 10Hz--is there any reliable way of determining compliance?

Yes. Use tracking force, either the median number of the published range or the recommended value. A more compliant cantilever requires less TF and vice versa. For hifi purposes, the low end of TF would be maybe 1g and the high end 2.5g. Keep in mind that it is the stylus that determines compliance, so if it is removable and has been changed, it is the current one that matters.

One must also figure in cartridge weight. Based on my experiments I have used 6g as the reference weight for a cart. If higher or lower you should add or subtract that difference from the tonearm mass. It might not be significant, but it could nudge a less favorable match in the right direction or make a bad match worse.

2. My arm mass isn't published. How do I know what it is?

Straight arms on Japanese tts from the 80s are low mass. Most s-arms are medium to high mass, usually in the 14-18g range. The headshell is included in the arm mass, and if removable, one has the ability to affect this. Using a lightweight headshell affords the best chance of matching the largest variety of cartridges and avoids problems with arm balancing. The newer Technics arms are 12g--that is published in their manuals. Most contemporary arms, like the Rega, are medium mass as is the Thorens TP16. The tonearm database at cartridgedb.com has mass figures for many popular arms.

There is a quick and dirty method of estimating arm mass. You need a digital pocket scale. Remove all weights from the tonearm. Leave a cartridge mounted but remove the stylus. Place the scale at the height of a record with the front of the cartridge resting on the scale. The resulting readout is the arm mass + cart body (without stylus) + mounting hardware. Subtract the cart body weight and perhaps .5g for the hardware and the result is your arm mass. I have tried this with arms of known mass and I've gotten results to within .5g.

So in boiling it all down, there is an easy "formula" one can use as a guide to arm/cart matching.

Low TF stylus mates with low mass arm.
High TF stylus mates with high mass arm.
 
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So that's why a Shure V15 works well with a low mass arm and a Denon DL-103 mates well with a high mass arm?

Hmmm interesting.:scratch2:
 
What Howard wrote, plus some less discussed matching issues:

Cartridge height: Some carts are taller than others (mounting plate to stylus distance). The height is an issue when adjusting cue raising height as well as VTA. The higher the cart the lower the VTA and the less options for adjusting it. Shorter carts produce a higher VTA (before adjustment) and they can be adjusted by an extra mat on the platter, spacers on the screws (they add mass though) or adjustment on the tonearm base.

Shell dimensions: Some headshells are small or narrow. Some carts are large and thy won't fit. I've read more than once here about removing the cart's "dressing" or scraping the headshell to make the cart fit on the headshell.

Regarding tonearm mass and Howards method of measurement, I'd like to comment that it's not only arm mass but also the distribution of that mass, i.e. distance of center of mass from the pivot point. A heavy headshell at a distance from the pivot creates a larger effective mass than a heavy arm with a lightweight shell.

I guess that's why some of the ULM tonearms (see Thorens) have a fixed headshell and a removable wand, moving the mounting towards the pivot point to reduce it's effect.
 
Hakaplan and Sasi have you covered. Modern headshells for S and J arms range from about 6.5 grams for the stamped aluminum ones up to 18 grams for heavy cast shells. I have had cartridge bodies that weigh as little as 4.8 grams, and some go up to 12 grams. These differences can have a more dramatic difference than arm mass itself and they allow you to "tune" around some possible problems. Getting an arm to balance with the counterweight in as close to the gymbol as possible is a good way to reduce moment of inertia and will help with tracking :)
 
I'm really glad the article I posted to be used as a starting point has stimulated some discussion on the topic.

There's allot of people who will learn from this (myself included).
 
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