Audio Technica AT33PTG/ii - compliance question

[hermit]

A friend has lent me the above cartridge and I want to mount it in a suitable headshell weight-wise. I want to use the vinyl engine cartridge resonance evaluator to help me choose which headshell to use. However AT publishes their dynamic compliance specifications relative to 100Hz. The specs for the AT33PTG/ii show 10 x 10-6cm/dyne (100Hz). The problem is that the VE cart resonance evaluator requires compliance figures measured at 10hz I believe.

Elsewhere on the web I read this:

"The cantilever is one of AT's fabulously thin boron things and it has a high compliance - 10 by the Japanese system (100Hz) which is around 20 by our system."

Could someone please advise me if this estimate of 20 would be a safe figure to choose for use with the vinyl engine cartridge resonance evaluator. If not 20 what figure should I use? Thanks in advance.

[walpurgis]

Do you know the effective mass at the headshell of the arm and headshell combination that is likely to be tried Paul? If not then a set of tables will be of no real use. Personally, I'd start with a lightish headshell and work upwards in weight/mass until things sound and work satisfactorily. At least that approach will do no harm.

[hermit]

Thanks Geoff. The effective mass of the arm is 16g and that is using the 10g headshell that came with the arm. If I use the 20 figure for compliance in the VE evaluator I am out of the green zone. However if I use my 6g ADC LMG-1 headshell this would reduce the effective mass of the arm to 12g, I believe, which puts me back in the green zone. That's why I was asking if the 20 figure could be relied upon.

[brozier]

The general view seems to be x1.5 to x2.0 to convert to 100Hz. I've been using the average of 17.5 for my AT33PTG2....

:)

[NRG]

As above, rough guide multiply by 1.75 to get the compliance at 10hz

[hermit]

Thanks for your replies chaps. Could I also just check that my understanding of effective mass is correct as my general ignorance knows no bounds? Is the bit I put in bold below accurate? Does using the 6g headshell reduce the effective mass of the arm by 4g to 12g? Thanks again.


Thanks Geoff. The effective mass of the arm is 16g and that is using the 10g headshell that came with the arm. If I use the 20 figure for compliance in the VE evaluator I am out of the green zone. However if I use my 6g ADC LMG-1 headshell this would reduce the effective mass of the arm to 12g, I believe, which puts me back in the green zone. That's why I was asking if the 20 figure could be relied upon.

[NRG]

Yeah, more or less (Barry posted how effective mass is calculated AFAIK in the knowledge section) but there's no need to get too anal about it, 12g seems just about right. I run my 33PTG/II in a Datum S which is 14g EM and it works just fine......

[Virtual-Symmetry]

I've never understood why people make this procedure of Arm/Cart matching so complicated.

:confused:

[hermit]

Yeah, more or less (Barry posted how effective mass is calculated AFAIK in the knowledge section) but there's no need to get too anal about it, 12g seems just about right. I run my 33PTG/II in a Datum S which is 14g EM and it works just fine......

Thanks Neal.

[hermit]

I've never understood why people make this procedure of Arm/Cart matching so complicated.

:confused:

It's not that complicated. Personally before spending a considerable sum on a cartridge, I rather like to check that it will not have a resonance problem with my arm(s) and that it will be a good electrical match to my phono stage(s). If it's a good physical and electrical match there's more chance of it working optimally in my system.

[Virtual-Symmetry]

Yeh i know it's not complicated, on contrary.. But i do read some posts on forum where people like to confuse the matter beyond belief..

I can tell you now that i have used some combinations that were technically disasters to only find they sounded fantastic..

However if your using 16g mass that should give you a near perfect match with that cart..

[hermit]

Thanks Andr'e. I'm quite new to this so this thread has been useful in reassuring me that I am using the VE tools correctly. Incidentally the good thing about this AT33PTG/ii cartridge is that it should work well with the Grace G707 on my TD125 too and that will be it's ultimate destination once I finish restoring that deck. In the meantime it'll work fine on my Kenwood KD-990's arm using the ADC LMG-1 headshell.

[Virtual-Symmetry]

The Grace it will indeed work fine. Heavier the head shell bolts should lower the resonant freq fractionally..

[mac72]

A friend has lent me the above cartridge and I want to mount it in a suitable headshell weight-wise. I want to use the vinyl engine cartridge resonance evaluator to help me choose which headshell to use. However AT publishes their dynamic compliance specifications relative to 100Hz. The specs for the AT33PTG/ii show 10 x 10-6cm/dyne (100Hz). The problem is that the VE cart resonance evaluator requires compliance figures measured at 10hz I believe.

Elsewhere on the web I read this:

"The cantilever is one of AT's fabulously thin boron things and it has a high compliance - 10 by the Japanese system (100Hz) which is around 20 by our system."

Could someone please advise me if this estimate of 20 would be a safe figure to choose for use with the vinyl engine cartridge resonance evaluator. If not 20 what figure should I use? Thanks in advance.

I'm afraid it's not so simple as multiplying by the single factor , if you look at different carts with compliance stated @100Hz this "factor" varies between 1.4-2.2 , there is too many variables involved .
You should buy HiFi News test record , you can check specific arm/headshell/ cartridge resonance , additional bonus are tracks to set anti-skating , tracking , etc..

[NRG]

Yes it is, people complicate these things way too much. I've used test records before on a number of cartridges and found the very rough guide of using 1.75 as a multiplier to work well in the real world. No need to spend extra on a test record.

[mac72]

Yes it is, people complicate these things way too much. I've used test records before on a number of cartridges and found the very rough guide of using 1.75 as a multiplier to work well in the real world. No need to spend extra on a test record.

AT95 6.5cu @ 100Hz - 15cu @ 10Hz - approx. 2.3.
AT440 10cu @ 100Hz - 18cu @ 10Hz - approx. 1.8.
AT-140LC 15cu @100hz - 22.5 @10Hz - conv is approx. 1.5.
Nagaoka MP-200 7.2cu @100hz - 14.5 @10Hz - approx. 2.0 .

Test record cost around £20 and anti-skate tracks are really helpful.
We spend hundreds & thousands on carts , decks , etc ... and skimp few quid on proper setup tools , another great tool is USB microscope - it takes an hour to check SRA angle so we don't go crazy constantly changing VTA

[Virtual-Symmetry]

:whistle:

[NRG]

Yup, I plugged the figures in for the AT95 and a 14g arm the difference was 9hz vs 10hz and for the 140LC it was the same at 7hz which is a bit out of range anyhow for either figure......

[mac72]

Yup, I plugged the figures in for the AT95 and a 14g arm the difference was 9hz vs 10hz and for the 140LC it was the same at 7hz which is a bit out of range anyhow for either figure......

I'd say 9Hz ( 8.96Hz to be specific) for AT95 is spot on , if you look at compliance of Clearaudio Concept MM which is AT95 in the metal body - 15cu , which confirms factor 2.3 .
Anyway , whole confusion about 1.75 comes from one of online compliance calculators stating that factor 1.5-2.0 should be applied , this is truth when it comes to majority of Japanese carts but some fall out of this range .
Regards