Arm effective mass confusion

[Marco]

Yes, but the subtraction doesn't apply in use because one would fit the headshell, therefore its individual mass would always be included in the overall equation, and thus affect how the cartridge behaves accordingly

I've never tried using the stock Technics arm without its headshell, but I guess that for DJs and other users alike, it would give a whole new meaning to the term 'scratching'!

Marco.

[sc_ita]

I have jusy found a service manual where it is clearly stated that the Tech has a "low 12-gram effective tonearm mass (including headshell, without cartridge...)".
You are right!
Now, I go immediately to add the 7.5g of lacking mass to my stock arm (slightly modded).

Thanks again, and good night,
Siro

[Marco]

Non c'e' problema - era una grande piacere!

Marco.

[DSJR]

I thought the arm seemed overly-lightweight as standard. IIRC, it's ancestors were rather more "solid."

[Marco]

I presume by that you mean the armtube itself, Dave? Perhaps; I'm not sure.

We're getting bogged down a bit with the headshell thing, though... The fact is, the headshell is an integral part of the arm and also the arm's effective mass.

Normally headshells are fixed, so the component parts of a tonearm, in terms of their individual mass, don't come under such scrutiny!

An overall mass of 12g is perfectly adequate, and is actually greater than that of some tonearms currently produced by so-called 'hi-end' manufacturers... Of course, in many circumstances, reducing mass is an essential part of a tonearm's design principles. Heavier is not necessarily better.

Much depends on the partnering cartridge as to how ideal or not an arm's effective mass is. It's certainly a significant bonus with detachable headshell arms that this can be 'tuned' to suit the needs of individual cartridges, depending on which headshell is fitted. You can't do that with an RB300, for example

In my experience also, low-compliance cartridges (such as the Denon DL-103) prefer mass applied at the headshell end, than on the armtube and associated assembly, as this is the 'business end' which affects the performance of the cartridge most in terms of its need for extra mass.

In actual fact, the DL-103 works best on a fairly 'lossy' arm of medium-mass as standard, fitted with a heavy headshell. This is precisely why the Jelco SA-750D works so well with the 103, when partnered with an Audio-Technica LH-18 or one of the heavy-duty NOS magnesium headshells I use. Excellent results can also be obtained with some unipivots, such as Hadcocks, providing that their headshells have been suitably 'bolstered'.

Marco.

[anubisgrau]

well, it has always been regarded as a ultra low mass arm.

[Chivas]

Is the Jelco 750D's effective mass 20g with the headshell then? What is the mass of the Jelco headshell?

Cheers