On Tue, 29 Sep 2009 09:19:41 +0100, Jim Lesurf
wrote:

In article , Trevor Wilson
wrote:

"Don Pearce" wrote in message
...


The damping should all be associated with the spring - which is the
stylus cantilever suspension. There should be no expectation of extra
damping associated with the arm bearing, which is ideally as free to
move as possible. Indeed damping of the arm bearing impedes arm
movement that is needed to prevent low frequency high-amplitude stylus
excursions.

In other words, what is being damped is the spring - mass system of
the cantilever and effective arm mass. The right thing to damp is the
spring involved in that resonant system. Ie, the damping must be in
the cartridge.

**Unfortunately when theory meets reality, things don't always go to
plan. In my long experience (30+ years) running dozens of different MC
and MM carts with dozens of arms (including most SME models), I have
found that arm damping is critical to decent performance with MC carts.
SME arms (knife edge bearing types) are amongst the worst choices for
MC carts. This arm is one of the best choices, IME:

http://www.dynavector.com/products/t.../e_507mk2.html

Even more unfortunately, a lack of damping in the stylus cantilever may
tend to produce a marked HF resonance. Damping of the arm won't fix that as
the arm isn't really involved.

One of the points that people nowdays seem to overlook is the work Shure
and others put into having optimal cantilever damping for HF reasons.
People seem aware of the high compliance and, to a lesser extent, low tip
mass, but damping rarely seems to be considered.

The presumption seems to be that when you see an HF resonance with a MM it
must be purely 'electronic' in nature. This isn't really the case. When
experimenting with electronic loading you may simply be trying to trade off
two quite different HF LP resonances - one electronic and the other
mechanical - to get an overall optimum. But so far as I know, this has
largely been ignored in recent decades. Preumably because of the
(incorrect) assumption that MC designs are immune.

Slainte,

Jim

How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance

d

"Don Pearce" wrote in message
...
On Tue, 29 Sep 2009 09:19:41 +0100, Jim Lesurf
wrote:

In article , Trevor Wilson
wrote:

"Don Pearce" wrote in message
...


The damping should all be associated with the spring - which is the
stylus cantilever suspension. There should be no expectation of extra
damping associated with the arm bearing, which is ideally as free to
move as possible. Indeed damping of the arm bearing impedes arm
movement that is needed to prevent low frequency high-amplitude stylus
excursions.

In other words, what is being damped is the spring - mass system of
the cantilever and effective arm mass. The right thing to damp is the
spring involved in that resonant system. Ie, the damping must be in
the cartridge.

**Unfortunately when theory meets reality, things don't always go to
plan. In my long experience (30+ years) running dozens of different MC
and MM carts with dozens of arms (including most SME models), I have
found that arm damping is critical to decent performance with MC carts.
SME arms (knife edge bearing types) are amongst the worst choices for
MC carts. This arm is one of the best choices, IME:

http://www.dynavector.com/products/t.../e_507mk2.html

Even more unfortunately, a lack of damping in the stylus cantilever may
tend to produce a marked HF resonance. Damping of the arm won't fix that
as
the arm isn't really involved.

One of the points that people nowdays seem to overlook is the work Shure
and others put into having optimal cantilever damping for HF reasons.
People seem aware of the high compliance and, to a lesser extent, low tip
mass, but damping rarely seems to be considered.

The presumption seems to be that when you see an HF resonance with a MM it
must be purely 'electronic' in nature. This isn't really the case. When
experimenting with electronic loading you may simply be trying to trade
off
two quite different HF LP resonances - one electronic and the other
mechanical - to get an overall optimum. But so far as I know, this has
largely been ignored in recent decades. Preumably because of the
(incorrect) assumption that MC designs are immune.

Slainte,

Jim

How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance



The energy is dissipated in the tonearm, not the cartridge. See:

"A decade ago, high-compliance cartridges were the rage and these needed to
mate with very low mass tonearms. However, today's heavier, lower-compliance
phono cartridges (especially moving coils) have required tonearm
designers/manufacturers to reorient themselves in the direction of medium to
high-mass arms. Further, some of the currently available MC cartridges put
back a tremendous amount of energy into the arm. This reflected energy takes
the form of standing waves, which travel up and down the length of the
tonearm, potentially creating mis-tracking problems and/or frequency
dependent cancellation. A well designed tonearm will dissipate this energy,
rather than reflecting it back to the cartridge. The ability of the arm to
accomplish this will be dependent upon bearing design, internal damping and
rigidity."


From he

http://www.gcaudio.com/resources/how...cartridge.html

Then stop worrying about it....

On Tue, 29 Sep 2009 13:53:12 +0100, "Keith G"
wrote:


"Don Pearce" wrote in message
...
On Tue, 29 Sep 2009 09:19:41 +0100, Jim Lesurf
wrote:

In article , Trevor Wilson
wrote:

"Don Pearce" wrote in message
...


The damping should all be associated with the spring - which is the
stylus cantilever suspension. There should be no expectation of extra
damping associated with the arm bearing, which is ideally as free to
move as possible. Indeed damping of the arm bearing impedes arm
movement that is needed to prevent low frequency high-amplitude stylus
excursions.

In other words, what is being damped is the spring - mass system of
the cantilever and effective arm mass. The right thing to damp is the
spring involved in that resonant system. Ie, the damping must be in
the cartridge.

**Unfortunately when theory meets reality, things don't always go to
plan. In my long experience (30+ years) running dozens of different MC
and MM carts with dozens of arms (including most SME models), I have
found that arm damping is critical to decent performance with MC carts.
SME arms (knife edge bearing types) are amongst the worst choices for
MC carts. This arm is one of the best choices, IME:

http://www.dynavector.com/products/t.../e_507mk2.html

Even more unfortunately, a lack of damping in the stylus cantilever may
tend to produce a marked HF resonance. Damping of the arm won't fix that
as
the arm isn't really involved.

One of the points that people nowdays seem to overlook is the work Shure
and others put into having optimal cantilever damping for HF reasons.
People seem aware of the high compliance and, to a lesser extent, low tip
mass, but damping rarely seems to be considered.

The presumption seems to be that when you see an HF resonance with a MM it
must be purely 'electronic' in nature. This isn't really the case. When
experimenting with electronic loading you may simply be trying to trade
off
two quite different HF LP resonances - one electronic and the other
mechanical - to get an overall optimum. But so far as I know, this has
largely been ignored in recent decades. Preumably because of the
(incorrect) assumption that MC designs are immune.

Slainte,

Jim

How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance



The energy is dissipated in the tonearm, not the cartridge. See:

"A decade ago, high-compliance cartridges were the rage and these needed to
mate with very low mass tonearms. However, today's heavier, lower-compliance
phono cartridges (especially moving coils) have required tonearm
designers/manufacturers to reorient themselves in the direction of medium to
high-mass arms. Further, some of the currently available MC cartridges put
back a tremendous amount of energy into the arm. This reflected energy takes
the form of standing waves, which travel up and down the length of the
tonearm, potentially creating mis-tracking problems and/or frequency
dependent cancellation. A well designed tonearm will dissipate this energy,
rather than reflecting it back to the cartridge. The ability of the arm to
accomplish this will be dependent upon bearing design, internal damping and
rigidity."


From he

http://www.gcaudio.com/resources/how...cartridge.html

Then stop worrying about it....


Ok, got that. But in order to stop worrying about it, I would have to
have started. Interested is altogether different.

d

"Keith Git is a Damn TROLL
"Don Pearce is a Prick "
How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance

The energy is dissipated in the tonearm, not the cartridge. See:


** KG simply does not read the context of the thread NOR the articles he
links.

http://www.gcaudio.com/resources/how...cartridge.html

The above is entirely about LF ( ie arm mass-cantilever suspension
compliance) resonance - in the range of 5Hz to 20Hz.

OTOH, cartridge HF mechanical resonance is a function of a cantilever's
stiffness and the mass ( ie magnet or coils) wobbling about at the opposite
end to the stylus.

Frequencies in the range from 10 kHz to 50 kHz are involved.

Anyone remember the massive spike in the response of the Decca London at 12
kHz ?

First class audiophool fodder that one:

" .... just listen to all that extra DETAIL ...... "

Allen Wright where are you ?


..... Phil

In article , Don Pearce
wrote:
On Tue, 29 Sep 2009 09:19:41 +0100, Jim Lesurf
wrote:


The presumption seems to be that when you see an HF resonance with a MM
it must be purely 'electronic' in nature. This isn't really the case.
When experimenting with electronic loading you may simply be trying to
trade off two quite different HF LP resonances - one electronic and the
other mechanical - to get an overall optimum. But so far as I know,
this has largely been ignored in recent decades. Preumably because of
the (incorrect) assumption that MC designs are immune.


How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance

One aspect of it - as explained in some ancient JAES papers by the people
at Shure - was to use suspensions whose effective 'resistance' increased
with frequency. Also to have a distributed arrangement for the suspension
so that some parts had more effect at HF than at LF. IIRC one of the
properties of 'rubber' materials is that the mechanical loss tends to
increase with frequency.

Another aspect is to have a material whose internal loss varies with
velocity or accelleration.

Note also that the cantilever resonance may not simply be the simple of the
displacement. It can be that the cantilever bends or flexes in the same
direction either side of the suspension. So that would affect the
suspension differently.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article , Keith G
wrote:

"Don Pearce" wrote in message
...


The presumption seems to be that when you see an HF resonance with a
MM it must be purely 'electronic' in nature. This isn't really the
case. When experimenting with electronic loading you may simply be
trying to trade off two quite different HF LP resonances - one
electronic and the other mechanical - to get an overall optimum. But
so far as I know, this has largely been ignored in recent decades.
Preumably because of the (incorrect) assumption that MC designs are
immune.


How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance


The energy is dissipated in the tonearm, not the cartridge.

Sorry, Keith, but you are confusing two quite different resonance
mechanisms. The HF one does not involve the arm. It is the resonance
between the effective cantilever inertia (not the arm) against the
suspension return force inside the catridge. So you can measure this and
observe it even when the cartridge isn't in an arm or touching and LP.

Whereas the LF resonance is between the suspension compliance and the
effective mass of the cartridge and arm. Quite different.

To make life more interesting, the effective return force versus
displacement at HF is quite likely to have a totally different compliance
value than the one exhibited at LF.


See:

"A decade ago, high-compliance cartridges were the rage and these needed
to mate with very low mass tonearms. However, today's heavier,
lower-compliance phono cartridges (especially moving coils) have
required tonearm designers/manufacturers to reorient themselves in the
direction of medium to high-mass arms.

To deal with the LF arm-cart resonance, not the HF one. The aim being to
put the LF resonant frequency at a relatively harmless frequency, between
warps and music, and to damp the peaking at that frequency.


Further, some of the currently available MC cartridges put back a
tremendous amount of energy into the arm. This reflected energy takes
the form of standing waves, which travel up and down the length of the
tonearm, potentially creating mis-tracking problems and/or frequency
dependent cancellation. A well designed tonearm will dissipate this
energy, rather than reflecting it back to the cartridge. The ability of
the arm to accomplish this will be dependent upon bearing design,
internal damping and rigidity."

Yes, and has little or nothing to do with either of the other two
resonances I am talking about. :-) You are correct. Low compliance MC
designs can give more problems with vibrations into the arm. But that is
another story to the two resonances we have been discussing.

From he

http://www.gcaudio.com/resources/how...cartridge.html

Then stop worrying about it....

Yes, I do have the impression that some MC designers may well have 'stopped
worrying about it'. :-) Alas, that may then cause their designs to have
resonances at HF which they haven't 'worried about' - or maybe noticed.

As Phil has said, these can occur in the 10's of kHz region. A problem with
MC designs is that the coils may contribute quite a large effective
intertia so far as the HF resonance is concerned.

These things were all investigated some decades ago, and reported in the
magazines and journals. People like Kogan of Shure knew well about them, as
I am sure (pun) so did others at Empire, Ortofon, etc.

But I am less confident about some modern carts which we are told were
designed 'by ear'. The best the user can do is hope to mitigate this by
playing with electronic loading. Or by using a differerent cartridge.

Maybe I should move up my 'to do list' writing about this.It seems to be
another aspect of LP engineering that has largely been forgotten since the
main engineering was done some decades ago.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

On Tue, 29 Sep 2009 16:35:45 +0100, Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Tue, 29 Sep 2009 09:19:41 +0100, Jim Lesurf
wrote:


The presumption seems to be that when you see an HF resonance with a MM
it must be purely 'electronic' in nature. This isn't really the case.
When experimenting with electronic loading you may simply be trying to
trade off two quite different HF LP resonances - one electronic and the
other mechanical - to get an overall optimum. But so far as I know,
this has largely been ignored in recent decades. Preumably because of
the (incorrect) assumption that MC designs are immune.


How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance

One aspect of it - as explained in some ancient JAES papers by the people
at Shure - was to use suspensions whose effective 'resistance' increased
with frequency. Also to have a distributed arrangement for the suspension
so that some parts had more effect at HF than at LF. IIRC one of the
properties of 'rubber' materials is that the mechanical loss tends to
increase with frequency.

Another aspect is to have a material whose internal loss varies with
velocity or accelleration.

Note also that the cantilever resonance may not simply be the simple of the
displacement. It can be that the cantilever bends or flexes in the same
direction either side of the suspension. So that would affect the
suspension differently.

Slainte,

Jim

Ok, that's interesting. Also interesting is the fact that A/T give two
compliance values for the OC9, static (35mm/N) and dynamic (9mm/N). I
wonder if this is to reflect the frequency dependence of damping. On
my 3009II the primary resonance comes in at 12Hz, which puts the
compliance in the same kind of region as the V15.

d
--
Pearce Consulting
http://www.pearce.uk.com

"Jim Lesurf" wrote

big snip

Yes, and has little or nothing to do with either of the other two
resonances I am talking about. :-) You are correct. Low compliance MC
designs can give more problems with vibrations into the arm. But that is
another story to the two resonances we have been discussing.


OK, seems I'm barking up the wrong tree here - thanks for taking the trouble
to explain!

(Phil's right, I didn't exactly read that article to death - only quickly
scanned it, as I usually do these days! :-)

Anyway, rightly or wrongly (and never having had a *low mass* tonearm to
worry about), I have always been under the impression that the (medium-high
mass) tonearm will usually take care of unwanted 'resonances' and that the
headshell (with or without a blob of Blu Tack and a handful of pound coins)
will take care of any (HF?) misbehaviour from within the cartridge itself??

Esoteric extremes aside, the reality is that most current carts seem to run
just fine on most current tonearms - according to recent posts, you have a
V15 on a (presumably) Technic S-shaped tonearm, Don runs an AT09 on an
SME3009 and I have a V15/III on a simple Lenco (tube and cube) tonearm as
well as an AT05 (I believe it is) on another Technics tonearm - all running
quite happily, I surmise?


Yes, I do have the impression that some MC designers may well have
'stopped
worrying about it'. :-) Alas, that may then cause their designs to have
resonances at HF which they haven't 'worried about' - or maybe noticed.


Maybe they are operating (as I do) under the banner 'if you can't really
hear it, it don't really matter'...??



As Phil has said, these can occur in the 10's of kHz region. A problem
with
MC designs is that the coils may contribute quite a large effective
intertia so far as the HF resonance is concerned.


'10's of kHz' definitely qualify as above - is there any 'side effect' that
I should know about?


But I am less confident about some modern carts which we are told were
designed 'by ear'. The best the user can do is hope to mitigate this by
playing with electronic loading. Or by using a differerent cartridge.


See above also, I'm fairly sure (another pun) that manufacturers
deliberately follow a 'one size fits most' path these days....



Maybe I should move up my 'to do list' writing about this.It seems to be
another aspect of LP engineering that has largely been forgotten since the
main engineering was done some decades ago.


Would it be worth your time an effort, given the ever-shrinking 'vinyl
user-base'..??

"Phil Allison" wrote in message
...

"Keith Git is a Damn TROLL
"Don Pearce is a Prick "


Jeez, Phil - how do you hope do expect to get treated with any respect in
here....??

Tsk tsk tsk... :-)


How does the HF damping thing work? It seems to me that if you can
dissipate energy quickly enough for critical damping at HF, it will be
almost solid at the main LF resonance

The energy is dissipated in the tonearm, not the cartridge. See:


** KG simply does not read the context of the thread NOR the articles he
links.


Oops!

Busted again! :-)

"Jim Lesurf" wrote in message
...
In article , Trevor Wilson
wrote:

"Don Pearce" wrote in message
...


The damping should all be associated with the spring - which is the
stylus cantilever suspension. There should be no expectation of extra
damping associated with the arm bearing, which is ideally as free to
move as possible. Indeed damping of the arm bearing impedes arm
movement that is needed to prevent low frequency high-amplitude stylus
excursions.

In other words, what is being damped is the spring - mass system of
the cantilever and effective arm mass. The right thing to damp is the
spring involved in that resonant system. Ie, the damping must be in
the cartridge.

**Unfortunately when theory meets reality, things don't always go to
plan. In my long experience (30+ years) running dozens of different MC
and MM carts with dozens of arms (including most SME models), I have
found that arm damping is critical to decent performance with MC carts.
SME arms (knife edge bearing types) are amongst the worst choices for
MC carts. This arm is one of the best choices, IME:

http://www.dynavector.com/products/t.../e_507mk2.html

Even more unfortunately, a lack of damping in the stylus cantilever may
tend to produce a marked HF resonance. Damping of the arm won't fix that
as
the arm isn't really involved.

**No argument from me. I refer you, again, to the Dynavector 17d (I,II,III)
cartridge. Their unique suspension system managed to push any resonance
issues well beyond 50kHz and out of harm's way. The arm design is to deal
with LF energy generated by most MC carts.


One of the points that people nowdays seem to overlook is the work Shure
and others put into having optimal cantilever damping for HF reasons.
People seem aware of the high compliance and, to a lesser extent, low tip
mass, but damping rarely seems to be considered.

**The art and science of arm/cartridge matching is a rapidly dissapearing
one. Even Shure have discontinued one of the finest cartridges ever
designed - the V15-V. Sad.


The presumption seems to be that when you see an HF resonance with a MM it
must be purely 'electronic' in nature. This isn't really the case. When
experimenting with electronic loading you may simply be trying to trade
off
two quite different HF LP resonances - one electronic and the other
mechanical - to get an overall optimum. But so far as I know, this has
largely been ignored in recent decades. Preumably because of the
(incorrect) assumption that MC designs are immune.

**On the contrary. Due to the low inductance of most MC designs, cantilever
choice becomes very important WRT HF response.


--
Trevor Wilson
www.rageaudio.com.au