As I would expect... if you calculate record thickness differences at the spindle hole and use the geometric formula from before, the angle differences are very tiny, hence the small arm travel.
The importance of VTA, SRA and Azimuth - pics
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As I would expect... if you calculate record thickness differences at the spindle hole and use the geometric formula from before, the angle differences are very tiny, hence the small arm travel.
That's what I've found over the years. Put on a well recorded piano recording and there's a very small increment where the instrument pops into focus. And I'm not buying Fremers explanation; if this sonic change is caused by headshell offset, then why do you hear these SRA changes with linear tracking arms?
You're right. THAT sonic change wouldn't be caused by headshell offset, but certainly there's another one that is. It's called Overhang! SRA is SRA regardless of type of arm. The only thing that can vary it or its sensitivity to adjustment is the stylus design.
Fremer is confused.
--Bill
Right. On clean well recorded and pressed records and with the A90, the correct spot is very narrow, probably .002 inch max on the ET2 scale. On cartridges with less contact area, or not totally line-contact (perhaps a contour instead) the range is much broader.
It's too bad records and pressings aren't more uniform, though. In my last series of listening tests with this new ground-up configuration/calibration, well done recordings such as Bill Evans "Waltz For Debbie", Alison Krauss & Union Station "So Long So Wrong" and of course many others I can easily find the idea spot for SRA, and it's quite a sharp little notch, but with a general broader effect of greater detail surrounding it up and down. Very clean and pleasant to listen to.
However, raise the cutting level a few dB and (at least) this Ortofon A90 gets cloudy and less distinct. The SRA broad range is there but not as obvious, and it's almost impossible to clearly delineate the precise point of best alignment. I have a number of records that behave like this on the A90, but not on the ZYX. In the case of the Alison Krauss album, of the four sides, side 2 is cut noticeably hotter that side 1 (on which SRA position is very clear and there's not a hint of mistracking), but side 2 has many areas which mistrack, mostly on vocal silbilance, and the general presentation of the side is nothing like Side 1. Side 3 is excellent, Side 4 is borderline, getting worse toward the inside diameter. It behaves like tracing errors in high lateral amplitude and higher frequency complex sounds. The current VTF is 2.5g which behaves the best in these regards. 2.3g (recommended) is similar but not quite as good overall, and anything below that is not acceptable. Azimuth is perfect (equal opposite channel crosstalk) and cantilever alignment is right on. So is overhang. These are the same or very similar results I've had with the two A90's across multiple complete ground-up installs.
Another extremely bad performing record is the QRP pressing of Cat Steven's Tea For The Tillerman. Yet it plays perfectly (except a hint of tracing difficulty at one place on side 2) with the ZYX. Other records where the A90 performs well, includes all the Sheffield direct recordings, many samplers and others.
Unless someone has some suggestions to try that I haven't already, I'm officially giving up on this cartridge and moving on (to what, unknown). The two A90's I've had just don't cut it for me.
BTW, all this haze from mistracking and tracing problems is clearly evident in a spectrum analyzer as out of band audio frequencies (>35khz to 60k or higher). Some records are low pass filtered at around 20.5k when cut, so on those the filter edge is quite clear in spectrum view, and any content above that is stylus chatter of one sort or another.
--Bill
This thread has been very informative and eye (or ear)-opening. Once correctly set up (with the help of a dealer), i usually just adjusted VTA by ear- easy enough to do on the Kuzma Airline- and pretty much left it at that.
Question: is there a decent USB microscope that has the necessary magnification range to do this without alot of ancillary horsing around to the microscope itself? (The USB microscopes I've seen online don't look terribly expensive, but I'm not sure what I'm buying).
Also, bonus points if there is one that could work straight up with an iPad, or small Mac laptop? (Dragging my crusty old Dell PC into the listening room would make me crazy!)
Thanks. And I agree about Fremer's article- i applaud him for his candid admission of error. I don't recall his offering an approach to readers to get it right, though.
Question: is there a decent USB microscope that has the necessary magnification range to do this without alot of ancillary horsing around to the microscope itself? (The USB microscopes I've seen online don't look terribly expensive, but I'm not sure what I'm buying).
Also, bonus points if there is one that could work straight up with an iPad, or small Mac laptop? (Dragging my crusty old Dell PC into the listening room would make me crazy!)
Thanks. And I agree about Fremer's article- i applaud him for his candid admission of error. I don't recall his offering an approach to readers to get it right, though.
I've been recommending the Dino-Lite, 4xx series range or higher for their higher resolution (which is, unfortunately, not what I have); Bill has a 400 series and his pictures are superb.
Thanks Ack. Mine is an AD413T. It does have pretty good resolution but for closer examination of the stylus greater than 200 power is necessary. But at 200 it does a good job. Check out PCGEARS for the line. Also, you need some method of holding it in position. The only thing I've found so far for that is their BIGC-MS36B stand and arms. It's a little mickey mouse and awkward, but it does work.
Yes, there is Mac software for the scopes, but I don't know anything about it in use.
--Bill
I also use the BIGC-MS36B stand and it does indeed work. I will get something in the 400 series soon - my resolution is just too low...
What does 'controlled' mean? No studies at all that I'm aware of. Just folks like me, Ack and a few others trying to clarify things and relate calibration to listening.
--Bill
You might be able to improve things by taking off the clear plastic nose of the scope, run mag full up, and focus by position. It will usually get you in closer.
I just ordered an AM4013ZT4 which is a 400-470x fixed focus scope, which you adjust focus by distance, 4mm to 7mm. Also an MS-15x Object Stage with XY Axis Adjustment, which may help getting some really tight shots.
--Bill
Mystery To Me
Ok, I've included a closeup of a London Reference cartridge with fine line stylus. This is with the cartridge/arm parallel to the record as suggested in the setup instructions as a starting point. They also mention it will probably be best with the arm adjusted slightly tail-down. I've used multiple lights to make the fine-line edge visible.
So what's wrong with this picture?
How can this stylus angle possibly be right? It flies against everything I think I know about tracking angles. Is this cartridge damaged?
Can someone with a London cartridge verify (even with a magnifying glass) the angle at which their stylus protrudes? I haven't mounted this completely yet because I don't want to damage records if it's wrong.
--Bill
Ok, I've included a closeup of a London Reference cartridge with fine line stylus. This is with the cartridge/arm parallel to the record as suggested in the setup instructions as a starting point. They also mention it will probably be best with the arm adjusted slightly tail-down. I've used multiple lights to make the fine-line edge visible.
So what's wrong with this picture?
How can this stylus angle possibly be right? It flies against everything I think I know about tracking angles. Is this cartridge damaged?
Can someone with a London cartridge verify (even with a magnifying glass) the angle at which their stylus protrudes? I haven't mounted this completely yet because I don't want to damage records if it's wrong.
--Bill
Just wanted to know if anyone had checked the reproducibility and accuracy of their measurements. For example, what is the precision of a single SRA measurement? Can you improve the precision and accuracy with practice? Between parallax, software, etc. there seems to be possibility for measurement errors.
While reading the SRA article referenced by Fremer (Risch and Maier, Audio, March 1981), the authors note that SRA during LP cutting varies from 91-95 degrees. They recommend SRA 92 degrees to approximate correct SRA. It seems to me that the magic 92 degree figure is a starting point for fine tuning, not the end destination for set up.
It really depends on the stylus. Some cuts and larger overall designs are pretty easy to see fairly accurately, certainly within 1/2 degree or so. Or better as you become familiar with using the Microscopes and aware of visual alignment issues. Others with very tiny styli are very hard to discern precisely where the ridges are that are the contact points for the groove wall. That's why we've been talking about higher-than-200 power microscopes to try and extract some of the obscured detail. Ultimately, what you end up without actually being able to see the ridges is a best guess and perhaps a general starting point.
I have never heard of any figures suggesting SRA of greater than 92.5 degrees. SRA in general is just a slight inward bias for the cutting stylus to throw off the lacquer 'thread' that comes as a result of the cutting. Even 92.5 degrees would be excessive in most cases. You only want to use enough to throw a decent thread for vacuum capture. Excessive SRA amounts would really interfere with the relationship between SRA and VTA when it comes to trying to play the resulting record!
Ultimately, your ears should tell you the exact spot (per record (side), unfortunately). Starting with a visual is to help put you in the right range, and for the curious to become frustrated trying to figure out the logic of some styli!
--Bill
I agree with Bill, and moreover, this thread is the closest to a "study" on this stuff that I have ever seen on the 'net. As discussed long ago, what we really need is an IMD measuring device and the appropriate record (like the Analogue Productions Ultimate Test LP) for the most scientifically-derived SRA setting.
Bill, that London stylus looks grossly way off. In the end, don't all manufacturers buy styli mounted on cantilevers from Namiki or Ogura? So if this one is not damaged, it looks like quality control is way down, both at the factory and the cartridge manufacturer.
Bill, that London stylus looks grossly way off. In the end, don't all manufacturers buy styli mounted on cantilevers from Namiki or Ogura? So if this one is not damaged, it looks like quality control is way down, both at the factory and the cartridge manufacturer.
Being the eternal optimist, I keep hoping for some other explanation. I noticed in measurements the tip is very very close to 15 degrees. Coincidence? Or might there be something that you relate to differently in a cartridge that has no traditional cantilever?
I've started mounting and calibrating it on the TT and will try a couple of unimportant records to see what happens. In looking at how it is positioned, the tie-back string and the pictorials of the internal mechanism (which is minimal and simple component-wise) something really serious would have to have happened to get it moved incorrectly into this position. Very puzzling.
--Bill
15 degrees is neither proper SRA nor VTA. I don't know what to make of it. You may want to ask them.
I think the powers that be should make this thread a sticky at some point. It is informative and fascinating. A couple of gratuitous observations: first, the variations Fremer found in the Lyra are a little frightening! (I have owned a few of their better cartridges and think of them as a high level manufacturer of good quality). Second, there appears to be a product by TTWeights that looks like a 2MP microscope marketed for this purpose, but for the same price, it appears that you can buy a much higher resolution device. Third, it appears to me that, except for extreme cases, you are setting SRA by raising or lowering the arm rather than using the equivalent of shims, so the focal point here is to concentrate on SRA, not on VTA?
My arm (a Kuzma Airline) allows easy, repeatable height settings and I have always 'tweaked' it depending on the record- to my ears, small adjustments can be quite dramatic, and that was particularly evident with the Lyra Titan i (but perhaps I had the same issue Fremer did).
In the wishful thinking department, I'd love a remote controlled arm height adjustment since my TT is across the room from the listening position. I know there were a couple at one point- that would be a cool aftermarket accessory but I don't know if the engineering would permit it to work universally, for a whole range of arms, and it would probably be costly. I don't care much about remote control for other purposes, e.g. volume, but that would be a 'killer app.'
B- on your Decca, whoops, i mean London, i sent you a PM with the name of a guy who is supposed to be a guru on set up of those cartridges, I don't know if he can help.
Best,
Bill hart
My arm (a Kuzma Airline) allows easy, repeatable height settings and I have always 'tweaked' it depending on the record- to my ears, small adjustments can be quite dramatic, and that was particularly evident with the Lyra Titan i (but perhaps I had the same issue Fremer did).
In the wishful thinking department, I'd love a remote controlled arm height adjustment since my TT is across the room from the listening position. I know there were a couple at one point- that would be a cool aftermarket accessory but I don't know if the engineering would permit it to work universally, for a whole range of arms, and it would probably be costly. I don't care much about remote control for other purposes, e.g. volume, but that would be a 'killer app.'
B- on your Decca, whoops, i mean London, i sent you a PM with the name of a guy who is supposed to be a guru on set up of those cartridges, I don't know if he can help.
Best,
Bill hart
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