Cartridge Compliance

the thin end of the wedge
JPK
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Cartridge Compliance

Post by JPK » 11 Oct 2010 01:14

Hi, I’ve been trying to sort out the different methods for specifying cartridge compliance. Is there a conversion chart posted anywhere?

I have a vintage Sonus Blue, 50 x10-6 cm/Dyne, also I have a Goldring 1042, 24 um/mn. I was looking at a cartridge with 16 mm/N.
If I did the math right um/mn is another way of stating mm/N? Is that correct?

Out of curiosity I was wondering how different mm/N compares to 10-6 cm/Dyne.

The Sonus is used in a ultralight ADC arm and the Goldring in a Rega 250(modded).

It’s frustrating if there is different standards and difficult to find info on simple conversions.

Thanks,
Joe

lini
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Post by lini » 11 Oct 2010 01:33

Joe: It all boils down to the same - whether you write it as xx mm/N, xx µm/mN or xx * 10^-6 cm/dyn. Some also simply use cu for "compliance unit".

Greetings from Munich!

Manfred / lini

Guest

Post by Guest » 11 Oct 2010 02:37

Hi,

As Lini has said they are all the same, cu, compliance uniits, but the
reality of how cu is specified is a complete pain, who cares about cu
at 100Hz (well you do for tracking ability) but what really matters
is the effective cu at around 10Hz for arm matching.

FWIW you have both cartridges in well suited arms.

For a ~ 15cu (at 10Hz) cartridge the Rega is well suited.

rgds, sreten.

JPK
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Post by JPK » 11 Oct 2010 03:58

Thanks lini and sreten,

The equations I found just seemed overly complex for the conversion.

I've been thinking about trying a LOMC cart in the Rega arm and they seem to be a little lower compliance then the Goldring.
Since I got back into vinyl, I'm trying to get a better understanding of all of this. I'm still thinking in the 70's-80-s when lighter everything was better.

I've read very nice things about modded Denon 103's, but they're heavy and very low compliance, ~5cu, heavy tracking etc. I'm looking more in the 15-18cu range. Thanks for confirming my calculations.

sreten, why doesn't anyone seem to spec the compliance frequency?

It may be useful to have the HFNRR test record? I believe they're the only ones with compliance test tracks?


Greetings from St. Louis, MO

Joe

Bebé Tonto

Post by Bebé Tonto » 11 Oct 2010 04:04

JPK, you can search the forum and other websites to check which cartridges are being used by other Rega RB250 arm users.

If you have a light ADC arm, i would immediately try an ADC XLM II, Super XLM or ZLM on it!! Those are fantastic carts!

lini
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Post by lini » 11 Oct 2010 11:15

Joe: The Denon DL301II and DL304 are pretty highly compliant (even though the compliance specs wouldn't seem so at the first glance, but those are measured Japan style (i.e. @ 100 Hz), so you can about double those numbers for a pretty good estimation on the dynamic compliance @ 10 Hz...) and hence would be suitable candidates for a light to very light arm. Whereas for an arm on the lighter side of medium heavy you've got quite a few more choices. What might be interesting at the moment in my view would be the Ortofon MC Salsa, as that has recently been discontinued, so one might find that for a pretty fair price (over here Williamthakker offers it for ca. 240 Euro (incl. 19 % VAT) at the moment...).

Greetings from Munich!

Manfred / lini

Guest

Post by Guest » 12 Oct 2010 21:13

JPK wrote:sreten, why doesn't anyone seem to spec the compliance frequency?
Hi Joe. It's because compliance@100Hz has a very different purpose, to define mechanical impedance and hence trackability@100Hz at a given VTF. It helps define required VTF.

The whole topic is inherently confusing, but compliance@100Hz is only a cousin of the spring constant which determines lf arm matching. Most of the accepted conversion 'calculations' are crude and can be quite inaccurate, IMO.

If one only knows compliance@100Hz, I wrote a calculator that allows one to determine arm matching/resonant f, based on assumption of damping factor being typically 0.05 - 0.1. In fact, it allows you to enter all manner of parameters, and predicts trackability/VTF required. Or conversely, trackability for a given VTF. It seems to usefully predict resonant f, versus various measured results, and generally agree with cart spec VTF ranges.

It's an excel spresdsheet. Appols it's complex, but so is the whole topic once one goes beyond the 'stiff compliance = heavy arm' level.

HTH.

Bebé Tonto

Post by Bebé Tonto » 12 Oct 2010 22:33

Thanks for the excel, Playing with it.

Info: For the Shure V15-IV these are the trackability limits at 1.0g:

400Hz: 29cm/s [10cm/s]
1000Hz: 42 cm/s [30 cm/s]
5000Hz: 47 cm/s [70 cm/s]
10000Hz: 37 cm/s [50 cm/s]

Values in braces are the highest levels on records, found by Shure engineers.

JPK
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Post by JPK » 13 Oct 2010 02:12

Bebé Tonto wrote:Thanks for the excel, Playing with it.

Info: For the Shure V15-IV these are the trackability limits at 1.0g:

400Hz: 29cm/s [10cm/s]
1000Hz: 42 cm/s [30 cm/s]
5000Hz: 47 cm/s [70 cm/s]
10000Hz: 37 cm/s [50 cm/s]

Values in braces are the highest levels on records, found by Shure engineers.
Ditto, Thanks for the spreadsheet, taking it for a test drive too!
Bebé Tonto, if I'm reading the Shure data correctly, it has problems at 5000Hz? Or does it need more VTF?

Joe

Guest

Post by Guest » 13 Oct 2010 06:30

A swift tutorial on how to use the spreadsheet based on the shure V15 IV example :

1. V15 IV compliance is spec'd at 32 cu (dynamic). Enter 32 in the dynamic compliance box. Being Shure, enter 10 (Hz) in the dynamic compliance frequency box.

2. Pick a value slightly higher than 32 (say 33), and enter in static compliance box. Play about with this number until damping factor = 0.05. In this case 32.3 cu, for example.

3. Choose the frequency at which trackability limit is known, or is of interest. In this case enter 400 in the 'lateral modulation frequency' box.

4. Choose a modulation amplitude according to the trackablity limit. Sometimes this is a an amplitude (um), and sometimes a velocity. Enter a number in the amplitude box to define the limit, in this case enter 0.23 , and check the corresponding velocity is 20 cm/s, being the rms the Shure spec trackability limit spec (29 cm/s peak).

5. The min required VTF box reports 2.06 gf. This does not agree with spec figure (1.0 gf). Try varying static compliance until required VTF = 1.0 gf. Enter static compliance = 32.07. Note damping factor is now 0.03, and min VTF is 1.07 gf. Close enough, and suspension damping is just abojut credible, but low.

What this predicts about the V15 IV is that suspension damping is unusually low. Presumably, that is why the lf stabiliser brush. Either that, or 1.0 gf 29cm/s@400Hz is optimstic, which is possible i suppose ! It is exceptional, of course.

Similar results obtain, based on the Shure 1kHz trackability spec.

The spreadsheet is only good for frequencies where compliance defines impedance, and up to c 1kHz is best.

HTH !

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Post by BigE » 28 Oct 2010 18:50

What is the level (riaa) box indicate?

I see these numbers change as the lateral frequency decreases. Why?

Guest

Post by Guest » 28 Oct 2010 19:08

BigE wrote:What is the level (riaa) box indicate?

I see these numbers change as the lateral frequency decreases. Why?
Hi BigE. The level box is the signal level both on the disc, and that would come out of the RIAA phono preamp. It's expressed in dB. dB is a ratio, relative to a standard level.

Basically, you need to decide upon a trackability target, in terms of level or in terms of amplitude or velocity. At a certain frequency. 315Hz is a standard trackability spec frequency. 100Hz is another.

For example, some cartridges specify, say, trackability is 70um@315Hz. then you need to enter 315 in the frequency box, and adjust the number in the level box until amplitude is 70um (or 140um pk-pk).

Or you might decide that +12dB@315Hz is your target. In which case, enter +12 in the level box, and 315 in the frequency box. This is an OK target, if you don't know what to go for.

I admit it's not very 'user friendly', I'm afraid !

HTH !

Bebé Tonto

Post by Bebé Tonto » 28 Oct 2010 19:56

Very good,

So basically we can assume a typically good cartridge is able to trace 60 to 80 uM of amplitude at 315Hz... which translates to 0.12 to 0.16 mm peak-to-peak,

usually we know the dynamic compliance either at 10Hz (usa spec) or at 100Hz (japanese spec), and the "recommended" VTF, which should be the VTF in which the amplitude at 315Hz quoted above should be traced.

So using this value we adjust the static compliance until the "minimum vtf" value is equal to the recommended VTF by the manufacturer.

With this then we can calculate resonance frequency, tonearm mass, etc.

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Post by BigE » 28 Oct 2010 20:33

Very interesting....

I got both static and dynamic figures for denon 301 from TVK. They are 13 and 35. When you put these in, with 315 hz and 0.16, you get a vtf of 1.87 gms.

This is over the mfg recommended tracking force. Same thing happens with the other "high compliance" denon's.

I have a 103D that looks to be the precursor of the 301 line. According to the calculator, I should probably run it nude to ensure that the system resonance is reasonably high. I should also run it at around 1.9 grams to track dynamic music properly.

Guest

Post by Guest » 28 Oct 2010 22:32

Hi BigE. Yes, by accounts the DL301II has 35cu@static and 13cu@100Hz compliance. Plugging these values in, i reckon trackability prediction equates to c 72um@300Hz for max spec VTF 1.6g. Which is not shabby.

Damping factor is 0.08, which is credible. Bit high perhaps.......are you certain of the 35cu@static figure (it suggests a double check IMO) ?

@Bebé Tonto, yes you've got the hang of entering what you know, and using it to work out what you don't. Damping factor is a key credibility check !

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