Tonearm/cart compliance

[Harleywood]

From what I've read a low compliance cart has a value less than 11 X 10-6 cm/dyne. My cart has a  value of 10. The arm on the sl1200gr is 12g with the headshell attached making it a medium mass arm. From what I gather I need to add three grams to my arm to get the mass up to 15 grams for my cart and arm to be a better match. Can this be accomished by getting a heavier headshell and am I on the right track and would the gains in audio quality be worth the effort? Still in a learning curve. Thanks!

[billybob]

Maybe George @MicroMara will have time to respond.

Thanks!

[MicroMara]

@Harleywood & @billybob   Just chim´in here .....

 

 

 

The issue here is the compliance of the needle carrier. The compliance indicates how hard or soft the suspension of the needle carrier is, which in turn carries the scanning diamond. The unit of measurement of compliance is µm/mN. It is measured at 10 Hz.Some of them measure at 100 Hz. There is also a distinction between dynamic and static compliance. The dynamic one counts; and it is obtained by dividing the static value by two.

 

MM and MI cartridges have a higher needle compliance than MC cartridges, these have a more stiffer needle compliance

 

Low compliance = hard suspended systems = values between 6 and 12 µm/mN
Medium compliance = medium hard/medium soft suspended systems = values between 11 and 22 µm/mN

High compliance = soft suspended systems = 22 to 30 µm/mN

Very high compliance = very soft suspended systems = 30 to > 40 µm/mN

 

Tonearms can be roughly classified according to the following scale

 

Ultra light tonearm: 4 to 5 grams

Lightweight tonearm: 6 to 9 grams
Medium-weight tonearm: 9 to 15 grams (most of the arms used today)
Heavy tonearm: 19 to 24 grams
Very heavy tonearm: 25 grams and more

 

For tonearms with exchangeable headshells this must always be included.

 

Tonearm and cartridge as spring-mass system

The mentioned values/classifications are important because the combination of tonearm and cartridge represents a spring-mass system. Like all classic spring pendulums, such a combination has a natural frequency that depends on the hardness of the spring and the mass of the whole system. This is the famous "moving mass", and only this is decisive: If the hardness of the spring increases (i.e. with lower compliance), the resonant frequency increases. If, in turn, more mass is added, the resonant frequency decreases.

 

The excitation of the mass-spring-system and the consequences

Now what happens if you excite this mass-spring-system with its natural frequency? Logically: it resonates, so that the oscillation becomes extremely upsetting. These oscillations in turn superimpose other frequencies. They lead to disturbances or booming and color the sound image or restrict the exact reproduction of the music. For example, if the resonance frequency was 40 Hz and you were playing a nice Kraftwerk disc, the needle could perform a dance and jump out of the groove.

 

Tonearm adjustment: many settings - lots of sound

 

When you start with the vinyl hobby, you think in a naive way: screw on the pickups, swing them out, roughly adjust the counterweight, and off you go. Unfortunately a wrong way - at least if you want to listen to music with high standards. Which pickup is already perfectly produced? Which needle is mounted exactly straight? Which needle carrier is at the exact angle in the generator?

 

Azimuth: mandatory setting of a good tonearm

 

The most obvious production errors can usually be detected with a sharp look at the needle carrier and needle. A magnifying glass or USB microscope can help enormously. If the needle or the needle carrier is obviously mounted crooked, you should complain about the pickup at the dealer. Slight misalignments can be compensated by using the mounting bracket in the headshell.

 

How to correct skewed needle carriers and diamonds

What can only be compensated for by adjusting the azimuth on the tonearm is a diamond inserted at a slight lateral angle, as unfortunately occurs in 80% of all cases with MC pickups. If you want an exact position of the needle in the groove and thus a perfect result, you have to measure and correct the azimuth. Many do this by ear. Respect, who can do that! The goal of an azimuth measurement is always to create a channel separation that is as equal as possible by using different angular positions of the headshell. With well produced pickups, the corrections are +/- 0.5 degrees or less to achieve the desired position. This sounds like little at first, but at one degree you can see the "skew" more than clearly.

 

The Tonearm Height (VTA = Vertical Tracking Angle) and the Stylus Rake Angle (SRA)

The second "big" control variable and hopefully also -screw on the tonearm is the height adjustment, the adjustment of the so-called "Vertical Tracking Angle". This is not very comfortable with some tonearms (Rega works e.g. with washers; but these arms are anyway mostly only interesting as a complete package with pre-installed pickups). With others like the above mentioned Reed 3P or the Aquilar from Acoustical Systems, the whole thing goes "on the fly" and extremely comfortable and sensitive with a rotating wheel.

What the height adjustment of the tonearm is actually about, is to trim the angle of the needle's insertion into the record to the angle specified during vinyl cutting. This way you can correct the SRA (the Stylus Rake Angle). The standard for this (exceptions confirm the rule) is around 92 degrees when the needle is dipped with the correct weight. Why not 90 degrees? Because the cutting graver scratches out material when cutting vinyl, and to prevent the material from accumulating in front of the graver, you admit a few degrees, i.e. you cut at a slight angle 92 degrees.

 

 

At this point I would like to emphasize once again that the described settings can be made by ear and taste, as always. Those who have practiced ears can and should use them. The bottom line is the same as with frequency response perception: what you really hear can also be measured. What cannot be measured is often only anchored in the human psyche.

 

More information under .....

 

[MicroMara]

2 hours ago, Harleywood said:

From what I've read a low compliance cart has a value less than 11 X 10-6 cm/dyne. My cart has a  value of 10. The arm on the sl1200gr is 12g with the headshell attached making it a medium mass arm. From what I gather I need to add three grams to my arm to get the mass up to 15 grams for my cart and arm to be a better match. Can this be accomished by getting a heavier headshell and am I on the right track and would the gains in audio quality be worth the effort? Still in a learning curve. Thanks!

Coming back to your basic question.....the compilance of your cart will fit to the tonarm mass , no problems ....of course it´s an option to optimize the performance with a more heavy headshell to upgrate the tonarm mass.

[Harleywood]

20 hours ago, MicroMara said:

Coming back to your basic question.....the compilance of your cart will fit to the tonarm mass , no problems ....of course it´s an option to optimize the performance with a more heavy headshell to upgrate the tonarm mass.

 

Thanks for the detailed info and link in your previous reply! I'm working with the other variables mentioned in those as well. Just needed some confirmation that I'm moving in the right direction and that I understand cart compliance and tonearm mass and their relation to each other. I actually have the cart mounted to a headshell that brings the mass of my arm to 14g right now. The ATHS1 headshell I'm using for that cart also accepts a screw in weight so I've picked up a 2g weight which brings the total mass of the arm to 16g. Much easier than changing headshells. Will be working with that this week and will take note of any changes. Thanks again!

[billybob]

And yes man...let us know the difference please.

Thanks!

[Harleywood]

Just now, billybob said:

And yes man...let us know the difference please.

Thanks!

Will do!

[Harleywood]

So I found the cartridge resonance evaluator on vinyl engine. https://www.vinylengine.com/cartridge_resonance_evaluator.php?eff_mass=12&submit=Submit

I also read that Japanese brands like Audio Technica rate their dynamic compliance at 100hz not 10 like most calculations are determined. So when I refer to the chart from the link above and enter 14g for my arm mass using the compliance of 10 for my 8g cart  I am barely in the green at 11hz. But if I take into consideration the rating at 100hz and multiply by ten I get a dynamic compliance of 20 for the cart and that puts me at the very bottom at 8hz. Am I trying to improve the rabbit hole or just digging in circles? 🤔

[MicroMara]

17 minutes ago, Harleywood said:

So I found the cartridge resonance evaluator on vinyl engine. https://www.vinylengine.com/cartridge_resonance_evaluator.php?eff_mass=12&submit=Submit

I also read that Japanese brands like Audio Technica rate their dynamic compliance at 100hz not 10 like most calculations are determined. So when I refer to the chart from the link above and enter 14g for my arm mass using the compliance of 10 for my 8g cart  I am barely in the green at 11hz. But if I take into consideration the rating at 100hz and multiply by ten I get a dynamic compliance of 20 for the cart and that puts me at the very bottom at 8hz. Am I trying to improve the rabbit hole or just digging in circles? 🤔

 

17 minutes ago, Harleywood said:

So I found the cartridge resonance evaluator on vinyl engine. https://www.vinylengine.com/cartridge_resonance_evaluator.php?eff_mass=12&submit=Submit

I also read that Japanese brands like Audio Technica rate their dynamic compliance at 100hz not 10 like most calculations are determined. So when I refer to the chart from the link above and enter 14g for my arm mass using the compliance of 10 for my 8g cart  I am barely in the green at 11hz. But if I take into consideration the rating at 100hz and multiply by ten I get a dynamic compliance of 20 for the cart and that puts me at the very bottom at 8hz. Am I trying to improve the rabbit hole or just digging in circles? 🤔

well ...if it´s 11 hz or 8 hz ..can be measured but can´t be audible for human ears .....don´t take it too seriouse ...😉. 

[Harleywood]

58 minutes ago, MicroMara said:

 

well ...if it´s 11 hz or 8 hz ..can be measured but can´t be audible for human ears .....don´t take it too seriouse ...😉. 

 

Right. It's probably close enough. Chasing shadows at this point.  At least I've done the legwork and I always get good advice here so when it's time to upgrade I'll be in a much better place. Thanks for your help! 

[billybob]

Yes, if sounds good, close enough.

[jorjen]

On 3/29/2022 at 12:09 PM, Harleywood said:

From what I've read a low compliance cart has a value less than 11 X 10-6 cm/dyne. My cart has a  value of 10. The arm on the sl1200gr is 12g with the headshell attached making it a medium mass arm. From what I gather I need to add three grams to my arm to get the mass up to 15 grams for my cart and arm to be a better match. Can this be accomished by getting a heavier headshell and am I on the right track and would the gains in audio quality be worth the effort? Still in a learning curve. Thanks!

Your compliance is 10 and the effective mass of your arm is 12? That is the arm and headshell but no cartridge? If so, what is the mass of the cartridge incl. fasteners? I may not be reading you correctly.