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Cartridge Compliance

kodawaru

kodawaru

New Member
This may have been asked before but I tried a search and really couldn't come up with a clear thread about cartridge compliance. I already have a vague idea, ie a high compliance cart is good for a low mass arm and a low compliance cart is good for high mass arms, and don't mix the two because it's bad for your vinyl.

So what exactly is this a measure of? How is it measured? Why do cartrigde manufacturers go with a certain compliance? Why are MM carts generally high compliance and MC carts generally low compliance? Any other little tidbits of info you'd like to share would be greatly appreciated.

So many questions so little time.

I'm trying to learn all I can about vinyl, already read tons of whitepages about vta and all that good stuff but couldn't find much about cartriges.
 
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I would also like to know how to determine if a tonearm is high or low mass.

Is there a way to know for certain other than just looking at the arm or guessing?
 
I'll be interested in responses to this too. I've come back to vinyl after a 20 year absence and am amazed how much the thinking has changed. I really don't understand why you would want anything BUT high compliance carts with low mass arms.
 
Compliance refers to how stiff or floppy the cartridge moving system is. The moving system in a cartridge is the cantilever, stylus and attached coils for MC cartridges, magnets for MM cartridges, or magnetic material for induced magnet or moving iron cartridges. A stiffly suspended cantilever/stylus assembly will have low compliance, and a very floppily suspended cantilever/stylus will have high compliance. It needs to be matched to a particular weight of tonearm, so that the fundamental resonance of the system is around 8-12 Hertz – 10 Hz is the ideal resonance. This is chosen so that it is above the area of record warp frequency, which is about 5 Hz or less, and below the area where rumble, both recorded on records, and from the turntable motor and platter, and feedback, will tend to cause problems – these usually occur at 15 Hz or higher.

The resonance of a particular cartridge and tonearm combination can be easily found by using a test record, such as the Hi-fi News and Record Review Test Record, or one of the excellent Shure V15 test records. The HFNRR test record is available new, and the Shure test records are regularly available on certain popular online auction sites. An expensive cartridge poorly matched to a tonearm so that the resonance is well away from the ideal 10 Hz can actually sound worse than a cheap cartridge which is well matched to a tonearm in some situations, so it’s worth getting it right to get the maximum from any cartridge.

If a tonearm looks and feels lightweight, it usually is. Most Japanese S-shaped tonearms (eg Technics SL-1200 tonearm) usually fall in the medium weight range, straight tonearms often fall in the light weight range, although the Rega RB250 and others arms based on it are classified as medium weight. The tonearm’s weight can often be found by checking the manufacturer’s specifications, or checking on the Vinyl Engine tonearm database, but really, all you want is a tonearm/cartridge resonance of 10 Hz – knowing the weight of your tonearm may make you feel better,:yes: but unless you get a cartridge to match it, it will be of little use.:thumbsdn:

A high compliance cartridge needs a light tonearm, and a low compliance cartridge needs a high mass arm, and a medium compliance....oh, work it out yourself - I'm sick of typing.:D

-Don
 
so, what you have is a damped resonant system (weight on a spring), known as a dashpot.
The physics of this, including the resonant frequency as it relates to mass and compliance, are well documented, and you can find an on-line calculator that will calculate the resonant frequency given a tonearm effective mass and stylus (suspension) compliance. You want to 'set' the resonance of the resulting system to the right frequency, which is hardly rocket science.

http://www.theanalogdept.com/cartridge___arm_matching.htm
"the effect is controlled by manipulating this frequency to exist in a range below human hearing but not so low that it will become excited by external vibrations such as foot fall disturbance or that of a warped record. This ideal frequency range is 8 to 12 Hz. The lowest of low organ notes rarely go below 20 Hz. [EDIT: I believe the lowest common organ fundamental is 16 Hz]. Footfall and record warps happen below 6 hz. "

The equation is given by these nice folks, too.

rf = 159 / sqrt ((eff. mass + cart weight + fastener weight) * (compliance))

[where]

rf: resonant frequency in hz
eff. mass: rated by tonearm manufacturer
cart weight: rated by cartridge manufacturer, but if accurate scales exist, an actual weight value could be used
fastener weight: screws, nuts, spacers, washers, shims. They have weight and add to the mass over the stylus
compliance: rated by cartridge manufacturer
 
Good thread!
Years ago I began messing with and modifying a simple arm/cart resonance "matching" spreadsheet that I downloaded off some web-site, perhaps Vinyl Engine? (not sure of the original author but... *respect*) I just added the "red light" vs "greenlight" stuff and added specs as I encountered them.

It quickly and visually lets you know when a cartridge-arm combination is within the 8-12Hz target window. I certainly don't mind sharing it so I've attached a copy. I was always going to modify it to give a different result in the event of near "perfect" matching (eg perhaps 9.5-10.5Hz) but I just never got around to it. But you can always just edit the target values in the colored results cells to suit your needs.

Just enter your current tonearm's effective mass and current cartridge data at the top and it will automatically show the expected results as well as for various other carts going down the page.If anyone notices any issues or errors in the specs please shoot me a note.

Enjoy

Regards
WopOnTour
 

Attachments

Is there a way to measure the arms effective mass if you don't have the manufactures specs like mhardy suggests?

I have a Pioneer PL630, Dual 1218 and a few other tt's but don't think they list it anywhere.
 
Compliance is also inversely related to tracking force. Light tracking forces require high compliance stylus as there is less downforce to act against when generating the signal. Higher tracking forces (DJ carts) can be built more ruggedly and stand back-cuing, etc. They have lower compliance suspension systems than audiophile cartridges. They are designed to be used more roughly. These cartridges generate their signal against this higher tracking force.
 
wopontour,

I extracted the files but can't open it. It says windows needs to know what program was used to create it. The ones I tried don't seem to be working.
 
BrocLuno said:
Compliance is also inversely related to tracking force.
Click to expand...
Right on the money. In fact, tracking force is the most reliable measure of compliance. Just to give a kind of guide, for hifi purposes 1g would be the extreme end of high compliance vs. perhaps 3g at the extreme low end of compliance. The middle of the suggested TF range is what one would use for comparison.

You will see compliance specs written as something like 20 x 10-6 cm/Dyne, which is the same as 20 CU (compliance units). The reason that compliance specs provided by manufacturers are not reliable is that they are not standardized. Often they are reported for 100Hz, when 10Hz is the more relevant frequency. This is further complicated by the fact that there is a static and dynamic compliance spec. The dynamic compliance listed over at cartridgedb.com for the AT440MLa, for example, is 10CU, which would make one think it is low compliance, but with a tracking force of 1.4g, it is actually high compliance. The compliance numbers listed there are misleading, incorrectly used, and generally worthless.

Regarding test records for measuring the resonant frequency, THE TONES ON THE HI-FI NEWS RECORD ARE INACCURATE so if you're buying it specifically for for that you're wasting a lot of money. The best records for measuring resonance that I know of are the Shure Era IV and Era V records. There may be others. I know Popular Science put one out, but I don't know what tests it includes.
 
DENNYDOG said:
Is there a way to measure the arms effective mass if you don't have the manufactures specs like mhardy suggests?

I have a Pioneer PL630, Dual 1218 and a few other tt's but don't think they list it anywhere.
Click to expand...
The only Japanese mfr I know of that lists arm mass is Technics. I measured the PL-630 to be about 15g. There is a quick and dirty method of measuring arm mass that is pretty reliable. You need a digital pocket scale, obtainable cheap on ebay. You would remove any counterweight and lateral weights from the arm. Place the scale in the area between the rest and the platter, ideally shimmed up to approximate the height of a record on the platter, but that's not critical. Remove the stylus. Set the arm on the scale so that the front of the cart is resting on the weighing area. Note the weight. From that number subtract the weight of the cartridge (minus its stylus, naturally) and you have a reasonable estimate of the effective arm mass.

Keep in mind that for calculation and comparison purposes, the mass includes the headshell, so that for arms with removeable headshells, you can change the mass by using a heavier or lighter headshell. Since s-arm users need to lighten the mass as much as possible in order to keep the resonant frequency up in the acceptable range, the Technics or Stanton headshell for Technics arms, and the generic grid headshell for most other arms, both weighing around 8g, are ideal.
 
Yup, the cheapie headshell off eBay - the stamped aluminum (silver or black) that comes with new wires for around $12 weighs in at 6.7 grams. Because it's at the end of the arm, that weight reduction helps a lot on S arms :)
 
I got a new AT150MLX cart for my Technics SL-1700Mk2, and mounted it on one of the early-style Technics headshells (with the single set screw on the top) Sunday morning. The AT150MLX is rated by AT as 10CU @ 100Hz, same as the AT440MLa, even though the suggested tracking force is lighter (0.75-1.75g for the 150, 1.0-1.8g for the 440). Does anyone have any idea what the true compliance numbers are for these cartridges at 10Hz?

After reading this thread, and guessing that I needed to take some mass off the arm to improve performance, I switched the AT150MLX over to a lightweight ADC cast headshell, that weighs 6.6g vs the 8.7g of the Technics headshell. I had to move the counterweight in just over 2 grams which confirmed that I had removed that much weight from the arm. The only drawback to the ADC headshell is that I have to adjust the VTA on the SL-1700Mk2 below the zero mark (around -1) to get the tonearm level.

The sound did seem to improve, but I don't know how much of that was due to the lighter tonearm, and how much was from (what I suspect was) a better job of aligning the cartridge in the new headshell. Either way, after a very hectic week or two, I finally had the chance to use my new cart on my new 180g pressing of In the Flat Field by Bauhaus, and it sounded mighty fine.
 
WopOnTour said:
Good thread!
Years ago I began messing with and modifying a simple arm/cart resonance "matching" spreadsheet that I downloaded off some web-site, perhaps Vinyl Engine? (not sure of the original author but... *respect*) I just added the "red light" vs "greenlight" stuff and added specs as I encountered them.

It quickly and visually lets you know when a cartridge-arm combination is within the 8-12Hz target window. I certainly don't mind sharing it so I've attached a copy. I was always going to modify it to give a different result in the event of near "perfect" matching (eg perhaps 9.5-10.5Hz) but I just never got around to it. But you can always just edit the target values in the colored results cells to suit your needs.

Just enter your current tonearm's effective mass and current cartridge data at the top and it will automatically show the expected results as well as for various other carts going down the page.If anyone notices any issues or errors in the specs please shoot me a note.

Enjoy

Regards
WopOnTour
Click to expand...

Thank you! Excellent spreadsheet. One suggestion: as per below, some of the "dynamic compliance" numbers are not all measured at 10Hz.
For example, try to find an arm that will be "compatable" with the ever popular Denon 103, Mass 10, Compliance (?Hz) 5.

Using this formula, and the Denon-reported specs, there are no arms that would work with the 103 cartridge. Nothing wrong with the formula per se, but with companies like Koetsu, Denon and AT, who stubbornly refuse to release useful and accurate specs.

hakaplan said:
Right on the money. In fact, tracking force is the most reliable measure of compliance. Just to give a kind of guide, for hifi purposes 1g would be the extreme end of high compliance vs. perhaps 3g at the extreme low end of compliance. The middle of the suggested TF range is what one would use for comparison.

You will see compliance specs written as something like 20 x 10-6 cm/Dyne, which is the same as 20 CU (compliance units). The reason that compliance specs provided by manufacturers are not reliable is that they are not standardized. Often they are reported for 100Hz, when 10Hz is the more relevant frequency. This is further complicated by the fact that there is a static and dynamic compliance spec. The dynamic compliance listed over at cartridgedb.com for the AT440MLa, for example, is 10CU, which would make one think it is low compliance, but with a tracking force of 1.4g, it is actually high compliance. The compliance numbers listed there are misleading, incorrectly used, and generally worthless.

Regarding test records for measuring the resonant frequency, THE TONES ON THE HI-FI NEWS RECORD ARE INACCURATE so if you're buying it specifically for for that you're wasting a lot of money. The best records for measuring resonance that I know of are the Shure Era IV and Era V records. There may be others. I know Popular Science put one out, but I don't know what tests it includes.
Click to expand...

Thank you for this. I thought I was losing my mind until you confirmed what I'd suspected. So how do we figure out true Dynamic Compliance at 10Hz, from a spec that is measured at 100Hz? I'm not a math wiz, but it seems like it should be simple algebra, no?

Why do these cart manufacturers publish 100Hz specs, when we need 10Hz specs. Is there a way to change the formula to use these 100Hz specs?

And what is "Static Compliance?" Why do manufacturers even bother to tell us that when they often don't tell us "Mass?" There must be a reason.
 
Hwsc said:
TSo how do we figure out true Dynamic Compliance at 10Hz, from a spec that is measured at 100Hz? I'm not a math wiz, but it seems like it should be simple algebra, no?

Why do these cart manufacturers publish 100Hz specs, when we need 10Hz specs. Is there a way to change the formula to use these 100Hz specs?

And what is "Static Compliance?" Why do manufacturers even bother to tell us that when they often don't tell us "Mass?" There must be a reason.
Click to expand...

I'm guessing there's no easy way to calculate the 10Hz compliance figure from the 100Hz figure. There's probably too many unknown variables having to do with the construction of the cantilever. And if that is the case, there's no way to modify the formula to take the "wrong" 100Hz figure instead of the 10Hz figure. One really needs the compliance figure at a frequency around or about the resonant frequencies being calculated.

Looks like my best bet will be to purchase a good test record and measure the resonant frequencies of my various cartridge/headshell/arm combinations.
 
I'm still curious as to why high compliance/low mass isn't always better. Maybe I'm paranoid, but maybe it's just more difficult/more expensive to manufacture these arms and carts?
 
secretguy said:
I'm still curious as to why high compliance/low mass isn't always better. Maybe I'm paranoid, but maybe it's just more difficult/more expensive to manufacture these arms and carts?
Click to expand...
It is, and for the most part that's what is being manufactured today.
 
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