MA-505 mass?

[Pryso]

I have a MA-505S that I will install after making some minor repairs. After wondering about the effective mass since the manual does not identify that, I've searched on VE and elsewhere. So far I've identified three different numbers: 7, 14, and 16.7 g. The latter figure seems to be the most probable but I would appreciate a confirmation if anyone can. I have the original headshell.

Also, I would appreciate knowing what cartridges any of you found that work particularly well with this arm.

Thanks

[Enochrome]

If the "s" in the MA505 is for silver than I am assuming it is still an s-shape tonearm? If it is, than the total mass of the arm is 16.7 grams. I had just read the manual and they state 7 grams for the wand and 9.7 grams for the original headshell. You here 7 grams from people who have mulitple cartridges with different weighted headshells so they don't consider the headshell part of the weight calculation.
I am not sure where the 14 grams comes from, that's just incorrect.

I have used the high compliance carts and medium/low compliance carts just by switching out heavier headshells or adding weights. To give you an example, I have used a ADX PSX-40 tracking at 1.25 to a Denon DL-103LC2 at 2.2 both having great results. I do have to admit that the ADC cart worked the best and is the biggest phono cart bargain out there today; it smoked the entire Grado Prestige line. The ADC -PSX-40 stylus is hyper-eliptical and only cost $30!!!

I recommend any cart with a compliance between 10 and 22. If you are using the original headshell
(9.7 grams) you cannot use a cart or add weight that is over 10 grams because the counterweight is not heavy enough.

For carts $100 - 200: Ortofon 2m Red, Audio Technica AT-7V, AT-120 & 440MLA(#1)
For carts $200 - 400: Denon DL-103, 110, 301; AT-33EV, AT-150MLX, SHELTER 201, or Grado Sontata.

[Pryso]

Many thanks Enochrome. I looked at the Operating Manual and the Service Manual for the MA-505 here on VE and all I found was the 9.7g for the headshell.

Yes, the S designation indicates silver wiring. That was a later upgrade after the arm had been introduced.

I don't understand how anyone would not include the headshell when considering effective mass. As I understand this, the sum of the arm, headshell, cartridge, and screws/nuts/washers should be included for total effective mass. Anyway, I'll go with your numbers and adjust only if trying a different headshell.

[Enochrome]

No sweat man!! Anything for a fellow Californian.
I just installed a Denon DL-103LCll because I am about to sell my Denon DL-110 and wondering if I'll miss the Denon house sound it provides. The 103 is at the lowest point of compliancy and highest point of weight which is the balance you want and it works fine. I am not kosher with the heavy tracking weight but that's how it goes. One day I want to retip it with a line contact so I can get that information that I know the conical stylus is missing.

[Yosh]

Hi

7g+9.7g=16.7g does not work in case of effective mass calculation:
1)the mass of shell is not centred on stylus point
2)weight is reduced to 80-90% as seen from stylus point.

http://www.fl-electronic.de/analog/tonarme.html
based on HiFi Choice indicated 14.5g

The correct calculation shoule be:
weight * SQRT(location of shell from pivot^2/effective arm length^2)
This can be applied on the mass of cartridge: actual effective mass of cartridge as seen at stylus point is reduced to around 90%.
The above equation is not usable at user end. Effective mass of arm is often misunderstood in such a way.

In any case 14.5g or 16.7g as arm mass is no problem for low compliance cartridges.

Regards
Yosh

[Yosh]

AMENDMENT OF ABOVE

I find my mistake.
The correct equation for effective mass of shell as seen from stylus point:
weight x (location of shell from pivot^2/effective arm length^2)
For example, 9.7g*(21^2/23.7^2)=7.6g

Excuse me for wrong input

Regards
Yosh

[JaS]

FWIW this arm comparison chart gives the effective mass as 14.5g, although it doesn't say how the figure was calculated.

viewtopic.php?f=66&t=2161

Regards,
JaS

[Pryso]

Hi Yosh

Thank you for attempting to answer. However I do not understand your information. Your math appears to calculate the effective mass of the headshell. I'm looking for the total effective mass of the MA-505 arm and original headshell.

Let me explain. I have a dozen various cartridges. To audition them, I would like to select those that would have the best apparent match with the MA-505 arm. My understanding is to add the effective mass of the arm and headshell to the weight of the cartridge and mounting hardware, then apply this figure to the compliance of my various cartridges in one of the resonance tables, looking for a value that falls between 8-11 Hz.

If my understanding is not correct, please clarify.

[Yosh]

Hi

You seem correct.

I have MA-505 original model.
In my use, from Ortofon SPU to Denon MC cartridges, the lateral low frequency resonances fall within 8-13Hz so that there is no problem. The real problem of low resonance is various but IMHO it is too much emphasized esp. when using too high compliance cartridges in the past - recent tendency in the market: the compliance is selected lower than 50cu except Grado? Also note that the compliance is fragile element tending to be changed by temperature, time and usage. IMHO it is better checking resonance frequency with test record or listening than arm-chair calculation using such elements (effective mass and compliance). Also note that resonance equation contains SQRT(mass*compliance) so that the difference between 14.5g or 20g coupled with 13cu or 20cu does not make double number.

The effective mass of tone arm MA-505 including standard shell 9.7g is around 14.5g as far as I tested with test record and various cartridges. It matches with arm mass 7g + shell effective mass 7.6g or around mentioned in my previous calculation: thus making total 14.6g for example.

Hi JaS
I believe that HiFi Choice checked effective mass by back calculation using test record. Even so there is a problem or dilemma in such test: there is no reliable compliance number and then back calculation based on resonance frequency leads to obscure effective arm mass number. Usually cartridge manufacturers except Ortofon are used to indicate static compliance and not dynamic compliance around resonance frequency 10Hz. And effective mass of arm is also changed by the position of a counterweight.

Regards
Yosh

[Cobra2]

I have tested a couple of 505 MkIII, and found, based on test-tracks (w/Denon DL-304 and AT-15SS carts) my arms had an eff.weight beteen 12 and 14g.

Arne K