Cartridge loading - does it matter?
 

Recommended loading is 100 ohms.


"Dave Plowman (News)" wrote in message
...
In article ,
Dish Guy wrote:
I only tried the 47K loading out of frustration with the lower settings.
All seemed to introduce something not quite right. I must admit that I
was surprised that 47K loading sounded as good as it did -- and better
than all lower impedances as well. As an added bonus (I guess) the S/N
ratio is higher with the higher loading.

What's the recommended load for the cart?

--
*When the going gets tough, the tough take a coffee break *

Dave Plowman London SW
To e-mail, change noise into sound.

Cartridge loading - does it matter?
 

Dish Guy wrote:
Does it matter? Probably not.

I use a Denon 103s MC cartridge (0.385mV) and after several months of
testing/listening recently I finally settled on 47K ohms as its best
termination resistance.

I tried several values, 40, 100, 200, 1000, 2000 ohms and 47K ohms. The
lower values displayed a slight resonance in the upper bass, about 1 dB or
so somewhere around the 80-100 Hz I would estimate, just enough to skew the
frequency balance for the male voice. The 1000 and 2000 ohm values smoothes
this low freq rise but then produced a peak in the 6 KHz to 8 KHz region.
The 47K resistance offers the smoothest and most extended frequency response
with neither of these two peaks being audible.

I only tried the 47K loading out of frustration with the lower settings.
All seemed to introduce something not quite right. I must admit that I was
surprised that 47K loading sounded as good as it did -- and better than all
lower impedances as well. As an added bonus (I guess) the S/N ratio is
higher with the higher loading.

Some years ago when Koetsu cartridges were widely thought to be the best
(maybe still are), there were suggestions in one or more of the comics
that they sounded better using 47k than the normal few hundred ohms. One
writer, (can't remember who) said he thought all MC cartridges sounded
better with a 47k load.

Unfortunately, and as is the wont of magazines, he never gave any reason
for his preference, nor backed it with any factual information. Could he
have been right?

S.






"Serge Auckland" wrote in message
...
I recently acquired a low output (0.2mV) moving coil cartridge
(Sumiko Talisman B), for which the manufacturers' recommend a load of
40-100 ohms. I am currently running it into a load of 47k as my standard
RIAA preamp has sufficient gain, albeit with a bit more noise than for the
earlier MM cartridge, but nevertheless, perfectly acceptable. My question
is:- as MC cartridges are voltage sources (and Sumiko's manual also says)
then why should the load matter once it is, say, 10x greater than the
source impedance of the generator, which in my case is 5.8 ohms. The
sound I'm getting seems fine, so I would like to know what
change/improvement I should expect from a lower impedance load.

Thanks

S.

Cartridge loading - does it matter?
 

Jim Lesurf wrote:
In article , Serge Auckland
wrote:

I recently acquired a low output (0.2mV) moving coil cartridge (Sumiko
Talisman B), for which the manufacturers' recommend a load of 40-100
ohms. I am currently running it into a load of 47k as my standard RIAA
preamp has sufficient gain, albeit with a bit more noise than for the
earlier MM cartridge, but nevertheless, perfectly acceptable. My
question is:- as MC cartridges are voltage sources (and Sumiko's manual
also says) then why should the load matter once it is, say, 10x greater
than the source impedance of the generator, which in my case is 5.8
ohms. The sound I'm getting seems fine, so I would like to know what
change/improvement I should expect from a lower impedance load.

Any changes would depend on details you have not given (and presumably are
unknown to you).

A lower amplifier input impedance might also provide lower noise.

As the amplifier is seeing 5.8 ohms, would a lower inpedance make any
difference to the noise?


Since no source will be an ideal 'voltage source' a lower load may also
change the frequency response, or distortion, or some other parameter.
Perhaps even alter the compliance to a small extent.

At some point the coil inductance, etc, may cause a resonance. Probably
well above audio, but might make something like RF pickup more possible in
some circumstances.

But none of the above may apply in your specific case.

I am sure you are right that lowering the load impedance will make a
difference. My question was about what sort of difference, and would I
be able to hear it - many things make measurable differences, but are
they audible......

Given the high output you could check by simply putting 100 Ohm shunts
across the amp inputs and see if this has any noticable effect.

Slainte,

Jim


Yes, that's my next experiment. I'll start with 1k and work my way down,
and see what (if anything) I notice.

Thanks

S.

Cartridge loading - does it matter?
 

I also have a Sumiko MC (albeit high-output). And I use the
Pro-Ject Tube Box. ISTR that it has a DIP switch array that
allows you to set the loading. I just left it on the setting
matching the recommended load for the cartridge. Maybe I should
have a play!

But not now: Doctor Who "The Impossible Planet" is on. That's the
first half of the double-episode with the Ood. The best Doctor Who
recently by quite a way!


"DON'T TURN AROUND. IF YOU LOOK AT ME, YOU WILL DIE."


Martin - AND YOU WILL WORSHIP HIM.
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

Cartridge loading - does it matter?
 

Jim Lesurf wrote:

A lower amplifier input impedance might also provide lower noise.

No. The source impedance sorts that out regardless.

At some point the coil inductance, etc, may cause a resonance. Probably
well above audio, but might make something like RF pickup more possible in
some circumstances.

It's *mechanical* resonance that's the issue ! A low load resistance can damp
that. The same happens with some well-known microphones btw.

Graham

Cartridge loading - does it matter?
 

wrote:

I have a cartridge that is also recomended to be loaded at 100 ohms. My
preamp allows for variable loading. At 47k it sounds more lively but
that livelyness seems to be a form of glare. Some people like this. I
don't.

Entirely unsurprising given that the source Z is inductive.

Graham

Cartridge loading - does it matter?
 

In article , Serge Auckland
wrote:
Jim Lesurf wrote:
In article , Serge
Auckland wrote:

I recently acquired a low output (0.2mV) moving coil cartridge
(Sumiko Talisman B), for which the manufacturers' recommend a load of
40-100 ohms. I am currently running it into a load of 47k as my
standard RIAA preamp has sufficient gain, albeit with a bit more
noise than for the earlier MM cartridge, but nevertheless, perfectly
acceptable. My question is:- as MC cartridges are voltage sources
(and Sumiko's manual also says) then why should the load matter once
it is, say, 10x greater than the source impedance of the generator,
which in my case is 5.8 ohms. The sound I'm getting seems fine, so I
would like to know what change/improvement I should expect from a
lower impedance load.

Any changes would depend on details you have not given (and presumably
are unknown to you).

A lower amplifier input impedance might also provide lower noise.

As the amplifier is seeing 5.8 ohms, would a lower inpedance make any
difference to the noise?

Probably not - depending on the reliability of the assumptions being made.

Couple of points as examples:

Firstly, is the source impedance genuinely '5.8 Ohms'? If the coils have an
inductance which is high enough it might cause the source impedance to be
somewhat larger than this value across some parts of the audio band.

Secondly, if the user was to employ an amp designed with a low input
impedance (as distinct from simply fitting shunt resistances to an amp with
an inherent high input impedance) then they might get a lower noise level,
and improved SNR.

e.g. compare a low-noise FET input amp with an inherently high input
impedance with something like a common-base bipolar amp. Their en/in ratios
will probably be very different.

If the source impedance is low, and resistive, then I wonder why changes in
occur the frequency response as the loading is altered... If this is due to
the effect upon generator 'compliance' then it seems efficiently coupled.




Since no source will be an ideal 'voltage source' a lower load may
also change the frequency response, or distortion, or some other
parameter. Perhaps even alter the compliance to a small extent.

At some point the coil inductance, etc, may cause a resonance.
Probably well above audio, but might make something like RF pickup
more possible in some circumstances.

But none of the above may apply in your specific case.

I am sure you are right that lowering the load impedance will make a
difference. My question was about what sort of difference, and would I
be able to hear it - many things make measurable differences, but are
they audible......

The difficulty is that the question is unanswerable without more
information. :-)

From what you have reported thus far, I suspect that any differences will
be between 'minor' and 'inaudible'.... but you may be able to correct this
in the light of experiment. :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Cartridge loading - does it matter?
 

In article , Eeyore
wrote:


Jim Lesurf wrote:

A lower amplifier input impedance might also provide lower noise.

No. The source impedance sorts that out regardless.

No, because a different amplifier design may have quite different noise
characteristics.

In practice, of course, the dominant noise source may be coming from the
actual LP surface. However if we ignore this, then the active devices in
the amp will probably be producing a larger noise contribution than the
thermal noise in the coil. There might also be a contribution from 'excess
noise' in the resistors in the amp which are passing bias currents.

The key point is that an amp designed to work optimally with a low input
resistance and source resistance will be different to one optimised for
higher impedances. The values for en and in will almost certainly be
different if the designer knows his job.

At some point the coil inductance, etc, may cause a resonance.
Probably well above audio, but might make something like RF pickup
more possible in some circumstances.

It's *mechanical* resonance that's the issue ! A low load resistance can
damp that. The same happens with some well-known microphones btw.

Being able to affect the mechanical resonances by altering the load on the
generator implies a reasonably high coupling (generator) efficiency. I
did wonder if this might be a factor, but don't know the specifics for
MC cartridges like the one Serge is using. Does that not imply that a low
load resistance will also cause the stylus forces to rise? i.e. to risk
an increase in record wear and/or distortion due to elastic deformations?
If so, presumably a higher load resistance might reduce the distortion.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Cartridge loading - does it matter?
 

Dish Guy wrote:
Recommended loading is 100 ohms.


Not so sure about that, the sheet that comes with the cart show the FR
plot with a 1k loading.

--
Nick

Cartridge loading - does it matter?
 

Dish Guy wrote:
Rega Planar 3 turntable, (new) RB-300 arm and Denon 103s cartridge.


In my (limited) experence, the Rega is a very poor match for the Denon.
It works much better with loose bearing arms like the SME, and its at
its best in a unipivot.

--
Nick