How does Cartridge Compliance and arm matching work?

[Beechwoods]

I'm a relative newbie to the dark arts of turntables and have no idea how one goes about matching a cartridge to an arm.

I have a feeling that Compliance refers to the 'give' in a cartridge cantilever and I understand that this has a synergy with the weight of the arm it's attached to. I have a couple of Technics SL1210's with stock arms and a couple of spare cartridges I want to play with on my second (play around) deck.

So what actually is Compliance? What would be the effect of getting the matching wrong? On my previous deck I found the stylus bent after a while and I wonder if that was because the arm was badly matched (that was a Lenco GL75 stock arm with Shure M75ED Type 2).

Are there any good resources on arm / cartridge matches?

Thanks for any advice everyone!

[MartinT]

Simply put, compliance is the flexibility or amount of 'give' in the cartridge's suspension. When you mount it to an arm, you have a spring/mass combination which will have a resonant frequency. Too low and the arm will wobble horribly on warped records and could mistrack. Too high and you may lose lower bass response.

The ideal resonant frequency should lie approximately between 8 and 12Hz.

Your example of a Shure M75ED, which from memory has a high compliance, and the Lenco GL75 arm which is a high mass arm, is a mismatch and would track badly with uncontrolled wobble. It could well have damaged the cantilever after a while. The addition of damping would have reduced the effect, but that needs an arm which has some form of damping available (think of a car which is a spring/mass but also has dampers to control body motion).

There's lots of information on the net, but a simple rule of thumb is: use high compliance cartridges (like the Shure and many MMs) with a lightweight arm (like the stock Technics). Use low compliance cartridges (like most MCs) with a heavyweight arm like the Jelco 750D, Ortofon, Dynavector arms etc.

[Beechwoods]

Thanks for the very clear answer Martin. I like your simple rule of thumb which will now be forever committed to memory! Sounds like both carts I have will be suitable for the Technics then, it'll be worth getting new stylii now :)

[MartinT]

I should have said that 'lightweight' and 'heavyweight' are just ways of visualising an arm's effective mass, which is the correct term.

[Beechwoods]

Effective mass is an interesting concept as when the arm is balanced the weight of the arm at the cartridge end is nil. I know mass is constant but weight is a force, balanced by the counterweight. At least I think I know!

[AlfaGTV]

Here (http://www.vinylengine.com/cartridge_resonance_evaluator.php) you can identify the most suitable combinations.

But the basic rules here stilll apply even if i consider the tone arm on a std Techie to be in the "middle" genre when evaluationg mass.. (12gr)

BR /Micke

Edit: Seems not suitable to link directly to the page, copy and paste the below adress:
http://www.vinylengine.com/cartridge_resonance_evaluator.php

[MartinT]

Effective mass is an interesting concept as when the arm is balanced the weight of the arm at the cartridge end is nil. I know mass is constant but weight is a force, balanced by the counterweight. At least I think I know!

Indeed, an astronaut can be weightless in space but most certainly has mass.

[Beechwoods]

That's the one!

[MartinT]

Edit: Seems not suitable to link directly to the page, copy and paste the below adress

Thank you, that's such a useful table that I'll reproduce the full URL here so that it can be copy/pasted into the address bar:

http://www.vinylengine.com/cartridge_resonance_evaluator.php

[Beechwoods]

Excellent link Micke - thank you!

[Barry]

Effective mass is an interesting concept as when the arm is balanced the weight of the arm at the cartridge end is nil. I know mass is constant but weight is a force, balanced by the counterweight. At least I think I know!

The effective mass of the arm is its moment of inertia about the pivot point, as seen by the cartridge stylus, divided by the square of the effective length of the arm.

The effective length of the arm is the distance between the arm pivot and the cartridge stylus. Since the distance between the cartridge mounting point and its stylus is now more or less standardised, the effective mass of an arm is determined by its design.

Given the arm and the cartridge, the resonant frequency of the arm/cartridge combination can be found by either using the calculator on the vinylengine web site cited above, or by hand as follows:

resonant frequency (in Hz) = 1/(2*pi*sqrt(M*C))

where pi = 3.142

M = effective mass of the arm + the mass of the cartridge + the mass of the cartridge fixings and leads (all in grams)

C = the cartridge compliance expressed either in cm/dyne, or as "compliance units (cu)" * 10^-6.

The resonant frequency ought to lay between 8 and 12 Hz. Too low (< 8Hz) and the arm/cartridge combination will be troubled by record warp (or by foot falls if the deck is not well isolated), too high (> 12 Hz) and bass performance is affected.

Regards

[AlfaGTV]

Apologies for the confusing links!

Nevertheless, if i understand correctly:
Selecting the effective mass for one of my tonearms, a SME 3009 S2 Imp which is listed as 9.5gr, gives a certain spectra of available combinations.
If i then, for example, chose to mount my Ortofon 2M Black onto that headshell that would give me the following data:
Cartridge Weight 7.2gr + mounting hardware, perhaps 1gr, allows a compliance of about 11 to 25.
If i understand Ortofons data correct the compliance for 2M Black is 22 µm/mN and that would be fine, resulting in a resonance of about 8Hz which is OK.

If i follow the same logic, mounting my Benz Micro Glider L2 (Compliance 15, mass 6.8gr) would also be OK, resulting in about 10Hz resonance.
I havent tried this latter one, but i was under the impression that it would not be the optimal config. So, i'll just have to try it out during the weekend!

BR /Mike

[Barry]

Apologies for the confusing links!

Nevertheless, if i understand correctly:
Selecting the effective mass for one of my tonearms, a SME 3009 S2 Imp which is listed as 9.5gr, gives a certain spectra of available combinations.
If i then, for example, chose to mount my Ortofon 2M Black onto that headshell that would give me the following data:
Cartridge Weight 7.2gr + mounting hardware, perhaps 1gr, allows a compliance of about 11 to 25.
If i understand Ortofons data correct the compliance for 2M Black is 22 µm/mN and that would be fine, resulting in a resonance of about 8Hz which is OK.

If i follow the same logic, mounting my Benz Micro Glider L2 (Compliance 15, mass 6.8gr) would also be OK, resulting in about 10Hz resonance.
I havent tried this latter one, but i was under the impression that it would not be the optimal config. So, i'll just have to try it out during the weekend!

BR /Mike

Hi Mike,

Without actually doing the calculations, I would have thought either cartridge would be fine in your SME arm.

I have used many cartridges in my SME arms and have never had a problem. You can get away with a lot if you use the SME damper.

I should have added in my previous reply that the compliance of a cartridge can also be expresed in micrometer/mN (= 10^-6 cm/dyne).

[Macca]

I'm using a Stanton 681 EEE in Sumiko headshell on stock Technics arm - I have had to fit the additional counter weight so I can balance the arm. Is this optimal? Seems to me I have a lightweight arm with a heavy weight at either end - from an engineering point of view would it not be better to use a lighter headshell and less weight at the back of the arm?

[Barry]

I'm using a Stanton 681 EEE in Sumiko headshell on stock Technics arm - I have had to fit the additional counter weight so I can balance the arm. Is this optimal? Seems to me I have a lightweight arm with a heavy weight at either end - from an engineering point of view would it not be better to use a lighter headshell and less weight at the back of the arm?

Possibly, but do the sums as described above. As long as the resonant frequency lays between 8 and 12 Hz don`t worry.

[Macca]

Possibly, but do the sums as described above. As long as the resonant frequency lays between 8 and 12 Hz don`t worry.

Do sums? Awww noooo....:eek:

[Barry]

Do sums? Awww noooo....:eek:

Fair enough Martin - you`ll have to wait until the end of the month when I return from Japan. I`ll do the calculations then, when I can lay my hands on the necessary data for your cartridge, headshell and arm.

Regards

[Marco]

How's the Sushi and the ladyboys out there, Barry (not necessarily in that order)? :D ;)

Anyway, hope you're having a fab time!

Marco.

[Barry]

How's the Sushi and the ladyboys out there, Barry (not necessarily in that order)? :D ;)

Anyway, hope you're having a fab time!

Marco.

Food is great, the weather indifferent, but the Japanese are unbelievably polite.

The trains and buses run on time and the loos have the most amazing range of optional extras (!) :eek: .

I haven`t, to my knowledge, seen any ladyboys - but I saw several meiko (apprentice geisha) in Kyoto.

The biggest test of restraint for me will be when I visit Akihabara. :)

Cheers

[MartinT]

The biggest test of restraint for me will be when I visit Akihabara. :)

Oh yes, I'm afraid I couldn't resist the vast Laox store the last time I was there. I hate it when they do export models and sell them tax free ;)

[sq225917]

All of which completely ignores the mass of the cartridge and the adjusted MOI of the arm according to counterweight position. The only way to be sure is to test with a suitable test record. The maths is a guide, not a solution.

[Barry]

All of which completely ignores the mass of the cartridge and the adjusted MOI of the arm according to counterweight position. The only way to be sure is to test with a suitable test record. The maths is a guide, not a solution.

No it doesn`t: see post 11. The calculation is only a guide. To do the job properly one would need to know the dynamic compliance of the cartridge at say 10Hz, or use a test record and an oscilloscope. No-one said it was a solution.

If you use arm damping you can get away with a lot.

[sq225917]

Read what I wrote , not what you think i wrote. You are in absolute agreement with me re, use it as a guide and measure it via record/scope.

I compounded the two 'terms' for cart weight and MOI of the arm, which is what happens in the real world, that's why the single figure for effective mass is pretty pointless as anything other than a guide.

I'm uncertain why you feel you need to denounce what i said when you then go on to state the same thing exactly, Are you the forum turntable guru or something. Has my expressing an opinion somehow belittled yours?

[MartinT]

I don't think Barry meant it in a challenging way, Simon. However, he does have a lot of knowledge of turntables, arms and catridges and we often appreciate his input.

[sq225917]

Martin, I have no idea as to his intent, nor do I really care. If he wishes to correct me though, then he needs to make a correction ;-)

[AlfaGTV]

Well, i did try my Benz Micro Glider L2 in the SME 3009 S2 Imp arm mounted to my TD-125 Mk I based on the advise from Barry and also the calculator on vinylengine.
The result was unfortunately a little disappointing.. :rolleyes: The combo lacked in dynamics, extension and sounded a little "uninteresting"... :(

However, my "old faithful" had done some travelling and was also stood aside for a couple of months or so before i tried the Glider on it. Following the initial disappointment i swapped back to my TD800/Rega/Benz Ace LS and enjoyed that combo a lot more.

I decided to give the "old faithful" TD125 an overhaul now that i had some time and the weather didn't exactly encourage outdoor activities.
Using our dining table as a service station the TD got some lube, a proper cleaning of all connectors and first and foremost the suspension adjusted.

I'm still baffled by the shocking difference! :stalks:
Now i fully agree that the Benz Micro is very comfy on the end of an SME arm, no problems here and the music this combo makes is really enjoyable! :)

By the way, you should have seen the look on wifey's face when she walks into our dining room! Me, back to the floor, wearing a flashlight attached with a headband for tennis and such, under the dining table which is parted as when inserting an extension, and the tt spread across the gap! Haha! :lol:

Br Mike

[MartinT]

Me, back to the floor, wearing a flashlight attached with a headband for tennis and such, under the dining table which is parted as when inserting an extension, and the tt spread across the gap!

LOL - an interesting method of turntable surgery that I shall consider replicating the next time I need to.