The importance of VTA, SRA and Azimuth - pics

[airbearing]

I used Sperling´ s PDM-1 Azimuth Controller. With the appropriate record by Sperling (DMM, one side 33, the other 45 rpm) you get the needed results, here for the Acoustical Systems Axiom Titan. If the instrument shows a result below of 10 pitch line, as it does here on the right and left channel, you may not change the Azimuth manually at the tonearm.


The following difference measurement of both channels shows nearly a 100 percent result. This is perfect – but not at every installation on different systems!


www.AudioCirc.com

 

[J.R. Boisclair]

SRA is in a sad state of affairs in the industry right now. Out of the last four cartridge measurements I've done, only ONE is within an acceptable +-2 degrees of error (actually, it was out of that spec by 0.16 degrees, but who's counting when they have all been such crap?!). The others at native SRA of 87.75 degrees, 88.6 degrees and 96 degrees. Those cartridges run the range from $2,000 up to $9,000.

Unfortunately, this is quite common and most people don't even know they are living with it.

When the error is that bad, there is no amount of tonearm height adjustment you can make to offer a perfect 92.25-92.65 degree static SRA (depending upon cartridge compliance) - especially on a 12" arm. You either need to send it back to the manufacturer for repair/replacement or have a custom designed wedge to place between the cartridge and headshell.

Dialing SRA in by ear on a cartridge like this would be an exercise in futility not only because you would not think it wise to play your arm at a very obvious angle but also because changes to SRA also impact azimuth in a big way - so what are you really listening to when you change the tonearm height? Of course, changing VTF also changes SRA. For your interest: Wally calculated that on the Kuzma 4Point mounted with a 35 um/mN compliant cartridge (very compliant) changes to tonearm height would result in NO changes to SRA due to the dynamic balancing of the tonearm.

FWIW: the one cartridge that was in the acceptable range belongs to a very famous audio reviewer. I wonder if the manufacturer gave HIS cartridge better QA since the same cartridge brand is also the one that comes in at 96 degrees and I have measured others of the same brand fairing quite poorly as well. Unacceptable for such a cost.

Some photos attached - including one bonus one showing uneven stylus wear on the right channel due to a flaw in the tonearm that had 10% anti-skating forces applied before the anti-skating mechanism was even applied. Notice that the apex of the shank is no longer on the centerline of the shank. The "real" anti-skating forces were off the scales of the WallySkater which has a practical limit of measurement somewhere around 18-20% of VTF. Again, this is the same turntable visited by two "setup experts" that weren't using the proper methods to assess each setup parameter without influence of other parameters. This is VERY important to get things right!

Listening for optimum alignment just won't do. When something CAN be measured for alignment purposes, it MUST be measured.

 

[Direct Drive]

SRA is in a sad state of affairs in the industry right now. Out of the last four cartridge measurements I've done, only ONE is within an acceptable +-2 degrees of error (actually, it was out of that spec by 0.16 degrees, but who's counting when they have all been such crap?!)

You are not the only one to say this. I was speaking to Dom at Northwest Analog (UK) as he is retipping my Mr Brier. He was making exactly the same observation that some cartridges are just shocking. Worse is the ones he was referring to are not the lower end of the price spectrum.

 

[tima]

The others at native SRA of 87.75 degrees, 88.6 degrees and 96 degrees.

When you say 'native SRA' do you mean with the headshell parallel to the record surface?

I understand reluctance to name names, but it might be one way to get manufacturers to do a better job, otherwise the same "sad state of affairs" may just continue. Can you say if you find certain brands tend to be more acceptable than others?

 

[ddk]

SRA is in a sad state of affairs in the industry right now. Out of the last four cartridge measurements I've done, only ONE is within an acceptable +-2 degrees of error (actually, it was out of that spec by 0.16 degrees, but who's counting when they have all been such crap?!). The others at native SRA of 87.75 degrees, 88.6 degrees and 96 degrees. Those cartridges run the range from $2,000 up to $9,000.

Unfortunately, this is quite common and most people don't even know they are living with it.

When the error is that bad, there is no amount of tonearm height adjustment you can make to offer a perfect 92.25-92.65 degree static SRA (depending upon cartridge compliance) - especially on a 12" arm. You either need to send it back to the manufacturer for repair/replacement or have a custom designed wedge to place between the cartridge and headshell.

Dialing SRA in by ear on a cartridge like this would be an exercise in futility not only because you would not think it wise to play your arm at a very obvious angle but also because changes to SRA also impact azimuth in a big way - so what are you really listening to when you change the tonearm height? Of course, changing VTF also changes SRA. For your interest: Wally calculated that on the Kuzma 4Point mounted with a 35 um/mN compliant cartridge (very compliant) changes to tonearm height would result in NO changes to SRA due to the dynamic balancing of the tonearm.

FWIW: the one cartridge that was in the acceptable range belongs to a very famous audio reviewer. I wonder if the manufacturer gave HIS cartridge better QA since the same cartridge brand is also the one that comes in at 96 degrees and I have measured others of the same brand fairing quite poorly as well. Unacceptable for such a cost.

Some photos attached - including one bonus one showing uneven stylus wear on the right channel due to a flaw in the tonearm that had 10% anti-skating forces applied before the anti-skating mechanism was even applied. Notice that the apex of the shank is no longer on the centerline of the shank. The "real" anti-skating forces were off the scales of the WallySkater which has a practical limit of measurement somewhere around 18-20% of VTF. Again, this is the same turntable visited by two "setup experts" that weren't using the proper methods to assess each setup parameter without influence of other parameters. This is VERY important to get things right!

Listening for optimum alignment just won't do. When something CAN be measured for alignment purposes, it MUST be measured.

Dear J.R. Boisclair,
Do you have a better alternative to listening?
Setting aside the extreme cases shown in your images considering the nature of “modern” cartridges and associated manufacturing processes I find the better manufacturers have achieved great consistency in their production for decades. Variation in styli is a known reality in the mostly hand manufactured phono cartridge and it’s not going to change anytime soon. A cartridge lives as a part in a loosey-goosey chain of unknown components with wide varying qualities and design issues, many poor. Not to mention the imprecise nature of the media it has to read and competence of the user doing the setup. Tight tolerance is relative here. The best and IME the only way for setting VTA/SRA properly is by listening, currently there are no tools that one can use to achieve set up as good as trained ears.

david

 

[microstrip]

SRA is in a sad state of affairs in the industry right now. (...)

Thanks for the great quality pictures. Can you describe us the set up you use to take them?

 

[J.R. Boisclair]

When you say 'native SRA' do you mean with the headshell parallel to the record surface?

I understand reluctance to name names, but it might be one way to get manufacturers to do a better job, otherwise the same "sad state of affairs" may just continue. Can you say if you find certain brands tend to be more acceptable than others?

I can say that SoundSmith mounts have been excellent so far. Its is VERY difficult to see the facet that actually rides inside the groove with their stylus profile, but their mounts are very spot-on in my opinion from what I've seen so far.

 

[J.R. Boisclair]

Thanks for the great quality pictures. Can you describe us the set up you use to take them?

I prefer an optical microscope because it is more stable when focusing and changing magnification levels. I am using the prototype of the WallySRA for the cartridge jig. I don't like to take the image while mounted to the tonearm. Too many variables you can't control for but still better than not doing it at all!

 

[J.R. Boisclair]

Dear J.R. Boisclair,
Do you have a better alternative to listening?
Setting aside the extreme cases shown in your images considering the nature of “modern” cartridges and associated manufacturing processes I find the better manufacturers have achieved great consistency in their production for decades. Variation in styli is a known reality in the mostly hand manufactured phono cartridge and it’s not going to change anytime soon. A cartridge lives as a part in a loosey-goosey chain of unknown components with wide varying qualities and design issues, many poor. Not to mention the imprecise nature of the media it has to read and competence of the user doing the setup. Tight tolerance is relative here. The best and IME the only way for setting VTA/SRA properly is by listening, currently there are no tools that one can use to achieve set up as good as trained ears.

david

Hi David

Thank you for responding. Please know that this question is not at all facetious and is genuine: which "better manufacturers" are you referring to? I would love to see more of them.

I will have to respectfully disagree with the assertion that listening is the best arbiter when it comes to MECHANICAL TRANSCRIPTION DEVICES that can be MECHANICALLY MEASURED. We know there is an electrical way to find best crosstalk separation, so we should do just that. We know there is a way to determine what angle the stylus is mounted at using an optical approach, so we should do that. We know there is a way to calculate and measure ideal anti-skating, so we should do that. ...and so on with zenith angle, etc. These methods do exist.

Listening by ear is never listening to ONE and only ONE parameter. When you change VTF, you change SRA. When you change SRA, you change azimuth. When you change azimuth, you change SRA (on most tonearms).

So, while I've no doubt that anyone can get a rig to sound "better" by using ear alone, you'll never KNOW whether you've dialed it in to perfection or not. Anyone with a 96 degree native SRA will never hear that cartridge at its best because who would think that it was "right" to drop the tonearm height down by nearly an inch off of level - and even if you could, many non-neutral balanced tonearms would start behaving very badly when severely angled.

 

[ddk]

Hi David

Thank you for responding. Please know that this question is not at all facetious and is genuine: which "better manufacturers" are you referring to? I would love to see more of them.

I will have to respectfully disagree with the assertion that listening is the best arbiter when it comes to MECHANICAL TRANSCRIPTION DEVICES that can be MECHANICALLY MEASURED. We know there is an electrical way to find best crosstalk separation, so we should do just that. We know there is a way to determine what angle the stylus is mounted at using an optical approach, so we should do that. We know there is a way to calculate and measure ideal anti-skating, so we should do that. ...and so on with zenith angle, etc. These methods do exist.

Listening by ear is never listening to ONE and only ONE parameter. When you change VTF, you change SRA. When you change SRA, you change azimuth. When you change azimuth, you change SRA (on most tonearms).

So, while I've no doubt that anyone can get a rig to sound "better" by using ear alone, you'll never KNOW whether you've dialed it in to perfection or not. Anyone with a 96 degree native SRA will never hear that cartridge at its best because who would think that it was "right" to drop the tonearm height down by nearly an inch off of level - and even if you could, many non-neutral balanced tonearms would start behaving very badly when severely angled.

Hi J.R.,

Ideally every cartridge will come with a perfect stylus and a tool that will give us the perfect SRA/VTA setting but we don't live in a perfect world so people have to pick up the slack. Also any tool is only as good as it's operator. Scales can be very accurate to 3 decimal points and you're given a narrow range for the tracking force to pick from, and still the final VTF is best decided by ear not the scale. I don't accept your position that you'll never know proper setup without a widget, it's a skill that people can learn and no different from any other skill set. The distinction between a good photographer and a mediocre one isn't the camera!

1" drop is pretty drastic, not a common issue and no reason to base everything off of extreme cases.

Companies like Ortofon, AT, Denon, and perhaps some others have a relatively consistent production but by no means is it perfect. The fact also remains that some artisanal cartridges sound better than any near perfect cartridge when properly setup and at least for now final VTF & SRA/VTA settings is best done by ear.

david

PS. I don't disagree with you that setting SRA/VTA is difficult and ideally there should be a way or tool to measure things and help with setup, my point is that people need to understand and develop some skill set too.

 

[J.R. Boisclair]

Hi J.R.,

Ideally every cartridge will come with a perfect stylus and a tool that will give us the perfect SRA/VTA setting but we don't live in a perfect world so people have to pick up the slack. Also any tool is only as good as it's operator. Scales can be very accurate to 3 decimal points and you're given a narrow range for the tracking force to pick from, and still the final VTF is best decided by ear not the scale. I don't accept your position that you'll never know proper setup without a widget, it's a skill that people can learn and no different from any other skill set. The distinction between a good photographer and a mediocre one isn't the camera!

1" drop is pretty drastic, not a common issue and no reason to base everything off of extreme cases.

Companies like Ortofon, AT, Denon, and perhaps some others have a relatively consistent production but by no means is it perfect. The fact also remains that some artisanal cartridges sound better than any near perfect cartridge when properly setup and at least for now final VTF & SRA/VTA settings is best done by ear.

david

PS. I don't disagree with you that setting SRA/VTA is difficult and ideally there should be a way or tool to measure things and help with setup, my point is that people need to understand and develop some skill set too.

Perhaps I have had my exposure under the microscope limited to the "artisanal" brands too much. I've never inspected a Denon or AT and it's been a long time since I've seen an Ortofon. I am certainly ramping up my exposure now as people are sending me more and more cartridges to inspect. I have started keeping a database of results - though I'm not quite sure what I'll do with it. I am not interested in "exposing" any manufacturer unless they don't stand behind their product defects. I'm sure at some point I'll find myself embroiled in a debate with a manufacturer as to what constitutes a "defective" mount. I do know that lathe cutter heads MUST be greater than 90 degrees and the further they stray from 91-93 degrees then the cutterhead has to begin fighting increasingly severe downward vector forces. I discuss that HERE.

Good point on the need for all of us audiophiles to develop some skills!

 

[ack]

it's been a long time since I've seen an Ortofon

I think. it's worth examining Ortofon, as they have the best reputation in the business for very high quality of manufacturing

 

[cuntigh]

Hello everybody,
Just bought a Tedeska mono cart. I just realized that the test record that is with the Fozgometer can’t be employed because it is made for stereo records and I’m afraid to ruin it with a larger mono tip.
Do some of you have experience and can share with me please ?

 

[J.R. Boisclair]

Hello everybody,
Just bought a Tedeska mono cart. I just realized that the test record that is with the Fozgometer can’t be employed because it is made for stereo records and I’m afraid to ruin it with a larger mono tip.
Do some of you have experience and can share with me please ?

The test track should be horizontally modulated only, in which case you'll be fine. It's not the stylus profile itself that causes groove damage, it is cartridge/tonearm resonance mismatch, egregiously bad alignment, too much or too little anti-skating, obnoxiously high VTF, shot bearings or using a cartridge with no vertical compliance on a stereo groove.

 

[ack]

Indeed true; just tracking a stereo disc with a mono cart is not an issue by itself

 

[cuntigh]

J.R and Acks thanks for your answers. The stylus is 1.7 microns that is for listening records from the 50’s early 60’s that are the major part of my mono collection.

 

[J.R. Boisclair]

J.R and Acks thanks for your answers. The stylus is 1.7 microns that is for listening records from the 50’s early 60’s that are the major part of my mono collection.

Perhaps you mean mils. 1.7 microns is smaller than any minor radius on any line contact stylus I’ve ever seen.

 

[cuntigh]

Oh yes you right. English is not my native language.

 

[ianm0]

SRA is in a sad state of affairs in the industry right now.

Measuring SRA using a microscope is not an easy undertaking if one thinks carefully how one has to align its axis absolutely perpendicular to the plane of the cartridge, as well as centering the stylus in the field of view. However measuring the cantilever angle is a lot easier. The correct cantilever angle while sitting on the record giving SRA = 2 deg is explained below.
First we need to measure - before the cartridge is mounted preferably - the angle between the two red lines in the photo using a microscope:


Then the correct cantilever angle giving SRA =2 deg can be calculated by 109.3 - 90 + 2 = 21.3 deg for this particular cartridge. Needless to say, sample to sample variation is always there.

 

[spiritofmusic]

I can say that SoundSmith mounts have been excellent so far. Its is VERY difficult to see the facet that actually rides inside the groove with their stylus profile, but their mounts are very spot-on in my opinion from what I've seen so far.

That's good to hear, I'm about to order two spare stylii for my Straingauge cart system.