I've found out that my Gemini PT-2000 has a tonearm mass of 9g, which
is lower than the Technic SL1200's 12g.

Does this qualify it as a high mass tonearm, therefore making carts
such as the Ortofon 510 or 520, with their high dynamic compliance of
25 µm/mN, or the OM 5E (20 µm/mN), unsuitable for use with this
tonearm? (in which case, can I assume I'd be better of with something
like the Ortofon OM DJ E considering it's lower dynamic compliance
9µm/mN, not to mention it's better trackability)


Doughboy

Doughboy wrote:

I've found out that my Gemini PT-2000 has a tonearm mass of 9g, which
is lower than the Technic SL1200's 12g.

Is this the "effective" mass (diff. from total mass)? If so, that's fairly low.


Does this qualify it as a high mass tonearm, therefore making carts
such as the Ortofon 510 or 520, with their high dynamic compliance of
25 µm/mN, or the OM 5E (20 µm/mN), unsuitable for use with this
tonearm? (in which case, can I assume I'd be better of with something
like the Ortofon OM DJ E considering it's lower dynamic compliance
9µm/mN, not to mention it's better trackability)


Is µm/mN numerically equal to the old compliance unit of 10^(-6) dynes / cm ? (I seem to recall that it is; am too lazy to figure it out for myself now.)


What's the mass of these cartridges?


James Boyk

On Tue, 02 Sep 2003 10:13:06 -0700, James Boyk
wrote:

Doughboy wrote:

I've found out that my Gemini PT-2000 has a tonearm mass of 9g, which
is lower than the Technic SL1200's 12g.

Is this the "effective" mass (diff. from total mass)? If so, that's fairly low.

Yes, Effective Mass (without cart) .

Does this qualify it as a high mass tonearm, therefore making carts
such as the Ortofon 510 or 520, with their high dynamic compliance of
25 µm/mN, or the OM 5E (20 µm/mN), unsuitable for use with this
tonearm? (in which case, can I assume I'd be better of with something
like the Ortofon OM DJ E considering it's lower dynamic compliance
9µm/mN, not to mention it's better trackability)


Is µm/mN numerically equal to the old compliance unit of 10^(-6) dynes / cm ? (I seem to recall that it is; am too lazy to figure it out for myself now.)

I have no idea. I did notice that Grado still quote their carts in
CU's, and quotes figures around 20, so probably.

What's the mass of these cartridges?

If cartridge weight is the same thing:

OM 5E - 5g
510MK II - 5g
520MK II - 5g
OM DJ E - 5g

Grado DJ100 - 5.5g



Doughboy

Doughboy wrote: ...my Gemini PT-2000 has a tonearm mass of 9g...

[cartridge mass & compliance]
OM 5E: 5g, 20 µm/mN
510MK II: 5g, 25
520MK II: 5g, 25
OM DJ E - 5g, 9
Grado DJ100 - 5.5g, Compliance not given


**
Assuming

(a) the compliance units are the same as the old-fashioned one,

(b) I remember the formula correctly:

Res. Freq. = 1000 / 2* pi * [sqrt [M*C)],

then---



OM 5E: 1000 / [6.28 * sqrt (14*20)] = 9.5 Hz


510, 520: 1000 / [6.28 *sqrt (14*25)] = 8.5 Hz


OM DJ E: 1000 / [6.28 * sqrt (14*9)] = 14.2


Grado DJ100: can't calculate w/out compliance figure.


Comment: The ideal range varies according to commentator, but no one puts it outside the range 10-14 Hertz. My preference is for 12-14. None of these quite fall in that range, but the OM DJ E is probably the most usable as getting the farthest from record warp (ca. 8 Hz) and footfall vibrations. I would not use the 510 or 520.

Much depends on the isolation of your turntable. If it's not isolated from sound fields of the music its playing, then run the monitor level way down or use headphones.

Of course there's more to a cartridge's performance than just this aspect. For instance, you might get a Shure V-15V/MR and use its damping brush. Even though it has high dynamic compliance, you might get better overall results with it than with any of these.


At some point you used the word "transcription." In the old days, this implied super-duper quality. If that's what you want, I doubt that any of this gear will give it.


James Boyk

On Tue, 02 Sep 2003 15:20:01 -0700, James Boyk
wrote:

Doughboy wrote: ...my Gemini PT-2000 has a tonearm mass of 9g...

[cartridge mass & compliance]
OM 5E: 5g, 20 µm/mN
510MK II: 5g, 25
520MK II: 5g, 25
OM DJ E - 5g, 9
Grado DJ100 - 5.5g, Compliance not given


**
Assuming

(a) the compliance units are the same as the old-fashioned one,

(b) I remember the formula correctly:

Res. Freq. = 1000 / 2* pi * [sqrt [M*C)],

then---



OM 5E: 1000 / [6.28 * sqrt (14*20)] = 9.5 Hz


510, 520: 1000 / [6.28 *sqrt (14*25)] = 8.5 Hz


OM DJ E: 1000 / [6.28 * sqrt (14*9)] = 14.2


Grado DJ100: can't calculate w/out compliance figure.


Comment: The ideal range varies according to commentator, but no one puts it outside the range 10-14 Hertz. My preference is for 12-14. None of these quite fall in that range, but the OM DJ E is probably the most usable as getting the farthest from record warp (ca. 8 Hz) and footfall vibrations. I would not use the 510 or 520.

Much depends on the isolation of your turntable. If it's not isolated from sound fields of the music its playing, then run the monitor level way down or use headphones.

Of course there's more to a cartridge's performance than just this aspect. For instance, you might get a Shure V-15V/MR and use its damping brush. Even though it has high dynamic compliance, you might get better overall results with it than with any of these.

Thanks for the useful info. It does seem that the OM DJ E is my best
bet. The Shure V-15V/MR (or even the M97xE) is too expensive for me.
As for the isolation issue, I'll just use headphones to monitor when
recording to avoid any complications, although I think the turntable's
feet offer quite good isolation.

At some point you used the word "transcription." In the old days, this implied super-duper quality. If that's what you want, I doubt that any of this gear will give it.

I probably shouldn't have used that word. I was just trying to convey
that I want to purchase a cartridge suitable for making reasonably
high quality recordings.



Doughboy

"Doughboy" wrote in message
...
On Tue, 02 Sep 2003 15:20:01 -0700, James Boyk
wrote:

Doughboy wrote: ...my Gemini PT-2000 has a tonearm mass of 9g...

[cartridge mass & compliance]
OM 5E: 5g, 20 µm/mN
510MK II: 5g, 25
520MK II: 5g, 25
OM DJ E - 5g, 9
Grado DJ100 - 5.5g, Compliance not given


**
Assuming

(a) the compliance units are the same as the old-fashioned one,

(b) I remember the formula correctly:

Res. Freq. = 1000 / 2* pi * [sqrt [M*C)],

then---



OM 5E: 1000 / [6.28 * sqrt (14*20)] = 9.5 Hz


510, 520: 1000 / [6.28 *sqrt (14*25)] = 8.5 Hz


OM DJ E: 1000 / [6.28 * sqrt (14*9)] = 14.2


Grado DJ100: can't calculate w/out compliance figure.


Comment: The ideal range varies according to commentator, but no one puts
it outside the range 10-14 Hertz. My preference is for 12-14. None of these
quite fall in that range, but the OM DJ E is probably the most usable as
getting the farthest from record warp (ca. 8 Hz) and footfall vibrations. I
would not use the 510 or 520.

Much depends on the isolation of your turntable. If it's not isolated
from sound fields of the music its playing, then run the monitor level way
down or use headphones.

Of course there's more to a cartridge's performance than just this
aspect. For instance, you might get a Shure V-15V/MR and use its damping
brush. Even though it has high dynamic compliance, you might get better
overall results with it than with any of these.

Thanks for the useful info. It does seem that the OM DJ E is my best
bet. The Shure V-15V/MR (or even the M97xE) is too expensive for me.
As for the isolation issue, I'll just use headphones to monitor when
recording to avoid any complications, although I think the turntable's
feet offer quite good isolation.

At some point you used the word "transcription." In the old days, this
implied super-duper quality. If that's what you want, I doubt that any of
this gear will give it.

I probably shouldn't have used that word. I was just trying to convey
that I want to purchase a cartridge suitable for making reasonably
high quality recordings.



Doughie, me old china, you're in danger of bashing your own brains out with
science.

I do not wish to 'diss' James' resonance calculations in any way, but I
would have to say I heartily disagree that the 510/520 options won't work as
I have run the 520 in a very similar tonearm (12 gm effective) and it was/is
my *favourite* out of the selection sampled on my Vinyl Page
http://www.apah69.dsl.pipex.com/keith_g/vinyl/vinyl.htm

At this very moment I am using my Debut deck with a 7.5 gm (effective)
tonearm and an Ortofon OM 20 cart (5 gm) but which has a claimed lateral
dynamic compliance figure of 25 µm/mN and a claimed tracking ability figure
(315 Hz) of 80 µm/mN. Now I don't know what James would make of these
figures, but all I can say is that it sounds absolutely superb and is
tracking perfectly.

In your first thread you say "With me it's normally the other way round, I
slam the needle onto the record, and then say 'f*ck it, I've bought another
cr*p stylus" " at some point. What we have tried to do here is to help you
avoid a repeat of that syndrome yet you seem to have made your mind up on
the OM DJ E with its very low compliance figure of only 9 µm/mN in a
low-mass tonearm which may well need a tracking force of as much as 4 gm to
work well - hardly the right/best formula for transcription work!

(Note cross-posting removed.)

Doughboy wrote: Thanks for the useful info.


You're very welcome.



...It does seem that the OM DJ E is my best
bet. The Shure V-15V/MR (or even the M97xE) is too expensive for me.
As for the isolation issue, I'll just use headphones to monitor when
recording to avoid any complications, although I think the turntable's
feet offer quite good isolation.


This is *extremely* unlikely. I've never seen feet that did. The only good isolation I've ever seen has come from a subchassis suspension a la Linn Sondek, AR or other similar turntables. But if the support is solid and there's no sound field for the turntable to need isolation from, things should be copacetic, as we used to say here in the '70's.



I probably shouldn't have used that word. I was just trying to convey
that I want to purchase a cartridge suitable for making reasonably
high quality recordings.


Of course I know nothing about these cartridges' sound quality, so you're on your own.


Good luck.


jb