Hi Folks
Halcro in your postings about the AT7V and the ATN155LC you asked about the reason for the differences between styli and the concomittant need for loading adjustments....
I've been thinking of writing a lot of this down.... an article for somewhere perhaps.
But taking a shot at it here and on the fly!
First the needles ability to follow the groove varies by shape and particularly by side radius... this will change the distortion levels (and some of that distortion may contribute to "enhancements" at certain frequencies)... but will not for the most part affect the fundamental "sound" of the stylus (in other words it affects fine details but not overall tone).
The cantilever is very much more critical:
1) it is the prime contributor to effective mass - and the lower the total effective mass, the better both tracking and high frequency becomes - this is however another "detail" aspect.
2) Mechanical Resonance and Damping thereof - this is the core and hub of the matter - the tone/sound of a stylus is fundamentally driven by this!
The frequency response of the stylus will be altered by the resonance, and by the damping (and suspension - which is part of the damping) used.
The Ortofon Ortophase article has graphs showing 4 different cantilever setups on an Ortofon MC200 cartridge - minimula/no damping through to heavily damped.
This affects the amplitude frequency response as well as the phase frequency response substantially.
Many of the cartridges regarded as "the best" have their resonances placed well outside the audio range (EPC100 well over 50kHz, Shure V15V 33kHz to 35k Hz)
Placing the resonance that high ensures that the stylus and cantilever can respond in a (relatively) pure linear way within the audio band... and a close to linear way well above the audio band.
Coming back to earth, and considering some styli I have measured....
The AT440MLa has a nice stylus and cantilever, but the mechanical resonance is spread from about 13kHz to 17kHz - the wide spread and "double peak" pattern of that resonance appears to indicate quite heavy use of damping... (internal to cantilever? - different materials in the suspension? not sure...) - Keep in mind that damping also does terrible things to phase linearity.... and these are difficult to measure or pin down subjectively...
So the ATN440MLa stylus has a tone which is driven by the raised area across the high frequencies - and the fact that this raised area is spread across a relatively wide frequency range.
Moving to the ATN15/20SS - with the beryllium cantilever...
The mechanical resonance is just barely outside the audible area (21k to 23k) but the rise to that peak has an influence down to around 15kHz.
because the peak is outside the audio area, it doesn't need to be damped so heavily - so the peak it much higher than the ATN440MLa peak, but its influence at 20kHz is only a touch more than the height of the ATN440MLa's peak - and by the time you get down to 16kHz the influence is negligible, where the ATN440MLa is at it's maximum influence around that frequency area.
The ATN15/20ss therefore sounds much more inherently neutral as a result (its midrange is well outside the influence of the resonance - where the ATN440Mla resonance influence extends down to 8kHz or perhaps even 5kHz)
3) Loading:
given a rise at the extreme high end, on the ATN20ss stylus - Neutral results require a load that drops off in an inverse relationship to the rise, resulting in a relatively flat frequency response. - This drop off needs to start quite late - so low capacitance and inductance is important, and avoiding high R loads as these may raise the high end exacerbating the already raised fundamental cantilever performance.
By contrast the ATN440MLa needs to have a rolloff that starts earlier as its own peak starts earlier - so different capacitance - and a lower R loading to keep from adding a rise in those frequencies...
You can see that these two cantilevers will have very different "sounds" - their fundamental frequency response is very different - and therefore the right loading to provide a flat F/R is different - the loading must match the stylus - not the cartridge! (the cartridge is of course a factor)
Now the cartridge - in the past I have said the cartridge has the least impact - which I still hold to, but they are interesting beasts too...
Cartridge electrical frequency response is NOT linear
A cartridge is a coil/magnet system much like a transformer, and suffers from increasing inefficiency as frequency rises.
The quality of the materials and construction will affect the level of inefficiency - as will voltage levels & frequencies involved.
What I am observing is that when looking closely at cartridge frequency response, all cartridges have a response peak in the lower mid/high bass region (between 150Hz and 300Hz) and then response shows a consistent downwards slope thereafter.
The angle of that downwards slope is most likely related to the effectiveness/efficiency of the construction.
This means that all magnetic cartridges tend to have a slight bass "hump" (the "warmth" of vinyl) and then a midrange slump.
Many cartridges then use a combination of electrical and mechanical resonance to "fill out" that drop.
(there is also a much more dramatic drop when the LCR response shoulder is reached...)
The better the quality of construction/design, the lower the slope angle - and the less need there is to use resonances to fill things out. (and therefore top end cartridges tend to push the resonances further out... because they can!)
You can easily plot the Inductance, Capacitance, Resistance frequency response of a cartridge, and then you can experiment with differing values of C & R which will show how the response can be tailored- high end can be raised or lowered, a peak can be induced, and the shoulder after which performance drops rapidly can be shifted back or forwards in frequency.
When you change styli - the cantilever F/R is different, and to balance it out, you then need to adjust the capacitance and resistance, to change the cartridge curve to properly match the cantilever curve and provide a "flat" frequency response..... so it is definitely stylus driven - not cartridge.
Using a different model form the same manufacturer, or using a stylus from an after market manufacturer - regardless of its quality - will require a change to the loading.
Another example - a Shure M97xE will tend to sound best at 62k with its original stylus, but tends to sound best at 47k with the SAS N97xE stylus...
Other cartridge related thoughts:
A cartridge is a self biasing environment - applying a voltage to the cartridge changes its frequency response (marginally but still changes!).
There are some discussions on VE about the possibility of phono stages providing some biasing voltage...
But the important thing to consider is that the signal produced - the music itself - is in fact a bias current, affecting the frequency response.
Keeping in mind that I am not a physicist or Electrical engineer.... but I believe that this biasing influence is non linear with voltage - that is to say, at lower voltages and inductances the influence of the sound may be proportionally reduced.
The advantage of LO systems may in fact be the improved linearity due to reduced self biasing influence.
This may also be one of the reasons why many of the higher quality styli have a lower output (along with having lighter magnets to reduce effective mass...).
Lower inductances tend to push electrical resonances further up the frequency range (good!) - but may also be shifting to a range where self biasing is also reduced....
In any case - coming back to the point... yes - loading follows stylus...
Switching AT cartridge bodies allows experiments with differing inductances and the same styli... the overall "sound" follows the stylus.
Differences tend to be driven first by the stylus - then beyond that there are the differences driven by the various types of non-linearities and the effectiveness of the designs in coping with them - areas where some people may not even hear a difference.
bye for now
David
Halcro in your postings about the AT7V and the ATN155LC you asked about the reason for the differences between styli and the concomittant need for loading adjustments....
I've been thinking of writing a lot of this down.... an article for somewhere perhaps.
But taking a shot at it here and on the fly!
First the needles ability to follow the groove varies by shape and particularly by side radius... this will change the distortion levels (and some of that distortion may contribute to "enhancements" at certain frequencies)... but will not for the most part affect the fundamental "sound" of the stylus (in other words it affects fine details but not overall tone).
The cantilever is very much more critical:
1) it is the prime contributor to effective mass - and the lower the total effective mass, the better both tracking and high frequency becomes - this is however another "detail" aspect.
2) Mechanical Resonance and Damping thereof - this is the core and hub of the matter - the tone/sound of a stylus is fundamentally driven by this!
The frequency response of the stylus will be altered by the resonance, and by the damping (and suspension - which is part of the damping) used.
The Ortofon Ortophase article has graphs showing 4 different cantilever setups on an Ortofon MC200 cartridge - minimula/no damping through to heavily damped.
This affects the amplitude frequency response as well as the phase frequency response substantially.
Many of the cartridges regarded as "the best" have their resonances placed well outside the audio range (EPC100 well over 50kHz, Shure V15V 33kHz to 35k Hz)
Placing the resonance that high ensures that the stylus and cantilever can respond in a (relatively) pure linear way within the audio band... and a close to linear way well above the audio band.
Coming back to earth, and considering some styli I have measured....
The AT440MLa has a nice stylus and cantilever, but the mechanical resonance is spread from about 13kHz to 17kHz - the wide spread and "double peak" pattern of that resonance appears to indicate quite heavy use of damping... (internal to cantilever? - different materials in the suspension? not sure...) - Keep in mind that damping also does terrible things to phase linearity.... and these are difficult to measure or pin down subjectively...
So the ATN440MLa stylus has a tone which is driven by the raised area across the high frequencies - and the fact that this raised area is spread across a relatively wide frequency range.
Moving to the ATN15/20SS - with the beryllium cantilever...
The mechanical resonance is just barely outside the audible area (21k to 23k) but the rise to that peak has an influence down to around 15kHz.
because the peak is outside the audio area, it doesn't need to be damped so heavily - so the peak it much higher than the ATN440MLa peak, but its influence at 20kHz is only a touch more than the height of the ATN440MLa's peak - and by the time you get down to 16kHz the influence is negligible, where the ATN440MLa is at it's maximum influence around that frequency area.
The ATN15/20ss therefore sounds much more inherently neutral as a result (its midrange is well outside the influence of the resonance - where the ATN440Mla resonance influence extends down to 8kHz or perhaps even 5kHz)
3) Loading:
given a rise at the extreme high end, on the ATN20ss stylus - Neutral results require a load that drops off in an inverse relationship to the rise, resulting in a relatively flat frequency response. - This drop off needs to start quite late - so low capacitance and inductance is important, and avoiding high R loads as these may raise the high end exacerbating the already raised fundamental cantilever performance.
By contrast the ATN440MLa needs to have a rolloff that starts earlier as its own peak starts earlier - so different capacitance - and a lower R loading to keep from adding a rise in those frequencies...
You can see that these two cantilevers will have very different "sounds" - their fundamental frequency response is very different - and therefore the right loading to provide a flat F/R is different - the loading must match the stylus - not the cartridge! (the cartridge is of course a factor)
Now the cartridge - in the past I have said the cartridge has the least impact - which I still hold to, but they are interesting beasts too...
Cartridge electrical frequency response is NOT linear
A cartridge is a coil/magnet system much like a transformer, and suffers from increasing inefficiency as frequency rises.
The quality of the materials and construction will affect the level of inefficiency - as will voltage levels & frequencies involved.
What I am observing is that when looking closely at cartridge frequency response, all cartridges have a response peak in the lower mid/high bass region (between 150Hz and 300Hz) and then response shows a consistent downwards slope thereafter.
The angle of that downwards slope is most likely related to the effectiveness/efficiency of the construction.
This means that all magnetic cartridges tend to have a slight bass "hump" (the "warmth" of vinyl) and then a midrange slump.
Many cartridges then use a combination of electrical and mechanical resonance to "fill out" that drop.
(there is also a much more dramatic drop when the LCR response shoulder is reached...)
The better the quality of construction/design, the lower the slope angle - and the less need there is to use resonances to fill things out. (and therefore top end cartridges tend to push the resonances further out... because they can!)
You can easily plot the Inductance, Capacitance, Resistance frequency response of a cartridge, and then you can experiment with differing values of C & R which will show how the response can be tailored- high end can be raised or lowered, a peak can be induced, and the shoulder after which performance drops rapidly can be shifted back or forwards in frequency.
When you change styli - the cantilever F/R is different, and to balance it out, you then need to adjust the capacitance and resistance, to change the cartridge curve to properly match the cantilever curve and provide a "flat" frequency response..... so it is definitely stylus driven - not cartridge.
Using a different model form the same manufacturer, or using a stylus from an after market manufacturer - regardless of its quality - will require a change to the loading.
Another example - a Shure M97xE will tend to sound best at 62k with its original stylus, but tends to sound best at 47k with the SAS N97xE stylus...
Other cartridge related thoughts:
A cartridge is a self biasing environment - applying a voltage to the cartridge changes its frequency response (marginally but still changes!).
There are some discussions on VE about the possibility of phono stages providing some biasing voltage...
But the important thing to consider is that the signal produced - the music itself - is in fact a bias current, affecting the frequency response.
Keeping in mind that I am not a physicist or Electrical engineer.... but I believe that this biasing influence is non linear with voltage - that is to say, at lower voltages and inductances the influence of the sound may be proportionally reduced.
The advantage of LO systems may in fact be the improved linearity due to reduced self biasing influence.
This may also be one of the reasons why many of the higher quality styli have a lower output (along with having lighter magnets to reduce effective mass...).
Lower inductances tend to push electrical resonances further up the frequency range (good!) - but may also be shifting to a range where self biasing is also reduced....
In any case - coming back to the point... yes - loading follows stylus...
Switching AT cartridge bodies allows experiments with differing inductances and the same styli... the overall "sound" follows the stylus.
Differences tend to be driven first by the stylus - then beyond that there are the differences driven by the various types of non-linearities and the effectiveness of the designs in coping with them - areas where some people may not even hear a difference.
bye for now
David