Thanks David for the link - interesting stuff. L_dog is saying the exact thing I just posted about the 440. Actual cu is more like 13 @100 Hz. Also, I always used more VTF - around 1.7 to 1,8g. The subject is complex and often one aspect of cart use (set-up) is substituted or used to compensate for another, like mass, bearing friction and damping. For those substituting styli, the cart will now take on the specs of the new stylus. For example, using a ATN155LC will give you a cu of 16 @100Hz.
Regards, |
What's often not taken into consideration is energy reflected back to the stylus from the record itself and its support, and the dissipation of energy through the arm to the counterweight and arm base and possibly the plinth. Knowing that energy can only be converted to another form and not lost, what happens to vibrations not transmitted due to isolation devices or poor transmission? Test reports of constrained layer damping between the cart and headshell show just how bad this is. IMO the cart has to be firmly attached to the headshell to maintain a fixed position, and to transmit vibrations to the arm. The more vibrations there are from the cart, the more this is crucial. Using mass to convert vibrations to heat is a most efficient way of dealing with this. Touch a vibrating tuning fork to a heavy rock, and the vibrations are quickly dealt with.
Regards, |
Hi Tubed1, Super tweeters? Ribbon tweeters typically have response to 40KHz. Some RAAL ribbons are claimed to have flat response to 100KHz. Fostex makes quite a few super tweeters with response to 40K. Some of the ribbons and the Fostex have high efficiency. Try Madisound. Parts Express also has a few ribbons with extended response.
www.raalribbon.com/ |
Ironically, kevlar woofers generally sound nothing like carbon fiber and are possibly the best types to mate with electrostatic panels to augment bass and compensate for lack of solidity. Even electrostatics with deep bass capability usually don't sound like natural bass. They might have the best midrange but electrostatics usually fall short in the high frequency dept as well. They typically lack the focus and imaging capability many value so greatly. But these generalizations don't necessarily apply to all examples, just as all kevlar woofers may or may not be worthy of target practice.
I had electrostatics with custom built direct drive amps. These amps produced 50KV and were astoundingly real sounding. Ribbon tweeters provided good high frequency detail and extension. Servo subs help in the bass dept, but must be crossed and EQ'd to make up for the deficiencies w/o putting the panels through a crossover.
In our attempts to minify a live musical event, physical limitations usually dictate capabilities. Specifically, size of radiating area vs imaging and focus, and ability of a flat panel dipole to produce natural bass. Not all electrostatics are created equal and some reduce panel size with frequency to overcome this imaging/focus problem. Not all dynamic bass drivers are created equal and Kevlar cones tend to be the better ones.
Regards, |
Hi Pauze, If the cart is resonating above the recommended range (8 - 12Hz), then it normally means your arm is too light, not too heavy. However, I wouldn't put too much stock in that especially if you switched to a light arm and there was no change. I don't know the compliance of the cart but maybe you should switch back to the heavier arm. You could even try a heavier headshell. From your description I suspect you're tracking too light. I think 1.9 or 2.0g is max, maybe you could take it up a bit. Assuming that your alignment is good and the needle is clean etc, maybe you just need some more hrs on the cart? It's a common fallacy that suspensions usually will harden with time. They almost never do. Even 30 + yrs ago they used synthetic rubber compounds that don't normally dry up. Suspension failure is almost always due to failure of the suspension wire. Break-in varies from cart to cart and some take a very long time. I don't have one of these carts so that's about all I can tell you. Many people start out with max VTF and back off some after the cart is performing properly.
Regards, |
Lew, I thought I'd get your goat with the electrostatic rant, although I put enough qualifiers in there that you could have felt exempt. I'm sure your Sound Lab are superb. In many speakers super tweeters are just tweeters with extended response and not add-ons. Some single driver full range speakers need a little help with the extreme high end. I think that's why Fostex makes quite a few. Although you're listening in the lofty world of ESLs, I'm back to dynamic drivers. Eton kevlar woofers happen to be some of my favorites, but I'd never let you get near with your target gun. LOL, my woofers are discontinued and I'd probably have to send them to Germany to be repaired. It's a little difficult to compare cone materials on different motors but the only thing that rivals for speed is metal, which has other problems. I'm sure you're looking forward to direct drive ESLs. Hope you have someone who knows what they're doing with the amps.
Regards, |
Yes the CA MM all share the same generator. I think the more expensive ones have closer tolerances. Once again, they do NOT have the same motor as the AT-95. They have the same body, cu and output. They might all have the same tip, a bonded .3 x .7 elliptical(?) on a straight alum cantilever. Stylus assemblies appear to be made by AT. Maestro is boron/micro, same cu and might also made by AT. Soundsmith $150 upgrade is tapered aluminum cantilever and a nude .3 x .7 elliptical. Obviously, this isn't an upgrade for Maestro.
Nandric, It's a shame that your miscommunication with Axel resulted in a HE tip on boron. I would have guessed that it would still be more refined than the aluminum/LC. We still don't know what a Maestro stylus sounds like on a Virtuoso. I suspect it would outperform them all.
Regards, |
Prof, I guess in 1980 the gentlemen at BAS, and possibly most people, only thought in terms of VTA/manufacturer spec and/or level cart top. As you know VTA is angle of cantilever to record and not SRA. SRA will vary for any given VTA, cart to cart. It will even vary for shibata tip, 2o I think. I believe that by 1980 standards were already changing for VTA, hence their recommendation.
For those interested in AS calibration, the Analogue Productions Test LP has a track that looks more reliable than HFN LP. Apparently both ch are modulated at the same time to + 12dB @ 315Hz and you can adjust by ear for breakup to occur equally in both ch or not at all. Most tracks require test equipment. I've read that fr sweeps in both HFN and AP LPs are off. I don't know how much Wally costs. AP LP is 45 - $50. If you have an oscilloscope you can align your cart with it.
Regards, |
Maybe because this forum is in English, my expectations for an understandable post on alignment and AS, are unreasonable? It seems to me that Lew and the Prof have the right idea. For the rest of you heathens, non-believers and sinners, it's like this:
Skating force on a pivoting arm is real and measurable. It is caused by the offset angle of the cartridge. That is the angle of the cantilever line, to the line of tip to pivot. The amount of skating force varies depending on position on record (offset angle changes) and stylus velocity. The imbalance caused by skating can be readily seen on VU meters or any output measurement. If you don't believe this is real, view your cartridge from the front, while tracking. Make sure you're directly in front and the lighting is even. Look at the cart body in relation to the stylus/cantilever. If the body is closer to the spindle, not enough AS. Conversely.... AS is applied to the arm, not the stylus. Because the amount of skating varies, an AS setting slightly low is usually recommended.
Next installment - Alignment
Regards, |
Dear Nandric, No specific language complaint here, it's just that I have enough trouble with English and my tongue gets caught in cheek. My mission is evangelical, i.e. to save souls from the damnation of the affects of unperceived distortions and unbalanced stage. One might wonder what these affects are if unperceived? They are like the plague of mediocrity that pervades our existence, the processed food of malnourished fat people, and the notion that if you don't hear it, it doesn't matter. Why would it matter one might ask? How could someone train themselves to hear distortion like Raul, unless they minimize distortion? Alignments are audibly different, long term. People can train themselves to hear, just like a musician trains to hear intervals, cords, modes etc. Changing alignments can be educational. Going from no alignment to a "good" alignment can be revelatory.
Regards,
|
Hi Lew, Yes, pretty much the same. I left out the part about stylus drag. Skating force is entirely due to offset, not tangency. Even if the cantilever is perfectly tangent to the groove (at a null), the back of it is not pointing at the pivot. It's that difference between the swing of the arm (pivot) and the angle of the cart, that causes skating.
Regards, |
Hi Mike, Not using AS does not cause distortion as such. It causes channel imbalance. It also causes skewed cantilevers and uneven (premature) stylus wear. Although once the cantilever is skewed, unless you realign to the cantilever it might cause distortion due to alignment error. This isn't a given though, depending on the new alignment.
Regards, |
Hi Nandric, I didn't mean to imply a correlation between being a heretic and speaking English as a second language. Actually, perhaps the contrary is true, at least for those in the US. When reading technical posts sometimes it's hard to figure out the meaning.
Although tracking is a 3 dimensional occurrence, alignment is 2 dimensional. What seems to be misunderstood is the relationship between alignments and the strict adherence to a particular alignment. There's nothing wrong with preferring an alignment, but sometimes it can't be achieved with certain arm/carts. For example, you might not be able to reach Loefgren B with an arm designed for Stevenson. In that case you could move the cart as far forward as possible and angle for the closest to Loefgren. That might give you Baerwald, or close. What I'm saying is that any 2 nulls between 60.3mm and 120.9mm is a "good" alignment. Look at the null points on the most popular alignments:
Baerwald - 66.0 and 120.9 mm
Loefgren - 70.3 and 116.6 mm
Stevenson - 60.325 and 117.42 mm
In reality, for most arms it takes moving the cart forward about 2 or 3mm and angling to go from Stevenson to Baerwald. It usually takes about another mm to go to Loefgren. This depends on the eff length. If you go to VE, they have a download called Chpratz protractor. This is just a straight calibrated grid. With it, you can see where exactly the nulls are. So, if your arm is designed for Stevenson, but you normally like Loefgren, you might prefer an alignment with nulls at 65 and 119? That's just a guess on how it might come out. Arc protractors are great if your arm is mounted at the exact distance. Even then it's good to use a second protractor to verify. I really like the Chpratz. It makes things easier, but I have quite a few protractors.
Regards,
|
Hi Prof, **Offset is the angle at which the long axis of the cantilever intersects that of the tonearm. In the case of a curved arm, the divergent angle at which it would intersect a straight line drawn from the stylus to the pivot. I mean, really, a tonearm could be as crooked as the twisted coat hanger wire that held the muffler up (radiator too) in my old 1960 Austin Healey 106 but offset angle is still reckoned relative to a point A to point B description.**
Do you have one of those Austin Healeys? What size engine?
Regarding your AS post, the long axis of the cantilever does not intersect that of the arm. If you draw a straight line extending the cantilever it goes off to the side of the table somewhere. It doesn't matter how many curves and angles the arm has, the offset angle is whatever is necessary to achieve a given alignment. That's it in a nutshell and why linear arms don't require AS. Longer arms have a smaller offset angle but usually have similar AS requirements. Perhaps mass or inertia have something to do with that.
Regards, |
Hi Timeltel, You're saying that overhang causes skating and not offset? Which came first, chicken or egg? The physicists explain it as offset. The stylus subscribes an arc from a theoretical pivot point that differs from the actual point of (arm) movement. Overhang is part of the equation, but the egg came first. Some bird laid a mutated egg and a chicken appeared. Or did some bird mutate and start a new species?
Aceman, I have a Stanton 980 which takes a D81 stylus. I have a Jico shibata replacement and a Pickering 3001 elliptical. The Jico is bonded and it's pretty good but not great IMO. You can use any Pickering 3000 through 5000 or the 7500. With the current prices you might want to consider having a stylus made to order.
Regards, |
Hello Prof, Your hot rod Healey sounds pretty cool. I'd replace that 3 speed with a 4 and get a 456 rear. Can you still get gas for that 11 to 1 bad boy? Easy for me to say, my hot rod days are long gone. Fastest car I ever drove (my friend's) was a '68 Z-28 trans America road racer. It was all aluminum drivetrain - 302 with a 4 speed/Hurst and a Holly 4-bbl that covered the entire top of the engine. It red lined @ 7000 RPM and did 60 mph in 1st gear. I drove it at 165 mph on the NJ turnpike late at night. Still had lots of pedal left. I doubt if someone could get away with that today.
Regarding overhang, the straight arm disco tables with no offset have tremendous amount of alignment error. Offset is required for all pivoting arms, regardless of overhang, to get a reasonable alignment. Offset angle is calculated from the stylus. One line follows the cantilever. The other goes to the pivot. The angle between those 2 lines is the offset angle. There is no other intersection of those lines.
The S and J shaped arms have similar offset angles as straight arms. They were developed to maximize structural rigidity for the headshell. They don't have the abrupt transition from line of pivot to offset like straight arms. Removable headshells for these arms allow the cart to be mounted straight in the shell and the arm is straight directly behind the headshell collar.
Regards, |
Prof, the intersection of the 2 lines is at the stylus. Any further extension gets into theoretical physics and I'm not qualified. I stand by my previous posts.
Lew, AS is caused because the line that determines offset angle is different from the stylus/pivot line that's actually moving the cart inward. It's this difference in angle that's the culprit, not lack of tangency. I think the Prof is right, further discussion on the cause of AS is probably counterproductive.
The D81S and the D98S are interchangeable. The other Pickering styli I listed will also fit. I don't know if there are any differences in stereohedrons. I also don't know about MKI vs MKII. Nandric says they're available from Germany. I never heard my 980 w/D98S. I was thinking of having a stylus made.
On another note, IMO the inexpensive ATN3472 series (P-mount) is superior to Jico ATN95 replacement styli for the Virtuoso. The cantilevers are thinner and response is faster. The AT-92E(CD) is also equivalent w/bonded .3 x .7 tip. You can buy the whole cart on ebay for $25. The 3472 variations are available with vivid line and orig ML styli from LpGear. You have to trim back the plastic wings and part of the bottom that hangs over. It will pop right in. VTF is 1.0 to 1.5g. I estimate ATN92E cu at 10 @100Hz.
Regards, |
LOL Aceman, 1000 hrs of Kenny G. Dude does not abide.
It seems to me there are different types of skewing, those from the factory and those as a result of incorrect AS. There are also different cantilever connectors to magnets or coils. Common sense dictates approach. A skewed cantilever on a new MC should be returned despite what any dealer might tell you. If it's very small amount you can align to the cantilever. Large amount of skewing in this case will limit excursion in one direction. In either of these cases no attempt should be made to alter factory orientation. If you have a small amount of skewing due to AS, sometimes you can successfully correct with orig alignment. Most HO carts have replaceable stylus and you might be able to see what's going on. If you're trying to correct a replaceable stylus you would align to the body or retain orig alignment. Inspection sometimes reveals the problem. I never try to bend a cantilever unless it's aluminum and it's for transplant. You only get 1 bend with alum, 0 bends with boron/beryllium.
Regards, |
Lew, **What causes skating forces is the fact that, with offset-angle tonearms, the LP groove pulls the stylus in two vectors at once. One vector is from the stylus to the tonearm pivot. The second vector is along the offset angle.**
Those vectors (skating) are still present at the null points, the points tangent to the groove. It is friction or stylus drag which is in line with the pivot and the offset angle at the same time, that causes skating. Linear arms have no skating, not because they're tangent to the groove, they have no skating because there is no offset. A straight pivoting arm with no offset will have no skating. Good luck trying to listen to it.
Regards, |
Hi Ecir, Mike, I looked at the photo of the microridge tip and it appears that the front and back surfaces are illuminated, rather than the sides. What is that ridge perpendicular to the lighted surfaces? The ridge should run side to side above the lighted surfaces. If those were the sides, the tip would be totally worn out, evenly. Tips don't wear in a rectangular pattern like that, and not perfectly even, at least not the scores of them I inspected. I looked at the photo a few times, even enlarged it with my browser. There's really no other way I can see it.
IMO The Shure stylus inspection microscopes are inadequate for proper inspection of a miniaturized tip like a microridge. They were designed for big conicals and ellipticals. Try 500X with an oil filled objective lens like an AT scope. Even 300 or 400X makes it much easier to see what's going on.
Regards, |
Hi Ecir, Sorry, I just can't see it. Take a gander at this pic of a microline. It looks the same as a microridge.
http://www.vinylengine.com/library/audio-technica/cartridge-guide.shtml
You're looking at the front of the stylus. In the pic you linked to, the ridge runs perpendicular to the lighted areas. How can that be?
If this is some kind of optical delusion, I apologize for giving you grief. I really can't see how it could be anything other than what I'm saying. The thinner parts of this stylus are the sides, which look like the top and bottom in the pic.
When a stylus is new, the light reflected off the side is like a point of light. As the tip wears, that point of light spreads into a circular or oval shape (not rectangular) and keeps spreading. With the light reflected here at 2700 hrs, the entire facet is lit up. It would have been impossible to play a record at 2600 hrs without severely damaging the record. The sides of that lit rectangle would be like razor edges. Even the most perfectly aligned carts don't display wear patterns like that. I can't accept this photo as proof of anything.
Regards, |
Ecir, the new pic looks like a normal stylus inspection view. Varying wear is easily seen, which is normal. The camera has nice resolution. With more magnification it would be a little easier for me to judge the amount of wear. With the AT scope they supplied pics of different types of styli and a guide to judge wear. They were all at either 300 or 500X. Good pic.
The first shot is still a puzzle. The rectangular patches of light look flat, like they're not even reflected off the tip. Is the cart still around, maybe you could shoot it again.
Regards, |
Lew, these forums are full of misinformation, but it seems like they're getting better. My understanding of AS was inaccurate until a tonearm designer and a couple of engineering types explained it. I like the story about the paddle and the river.
Prof, LOL a conical paddle. Who else would come up with that? What do you call that, reducere ad absurdis? Offset has always been about optimising alignment. I can't think of another reason to employ it. You probably can though. Any other earthshaking revelations in the Sony stuff?
Regards, |
Ecir, In the '80s I was the turntable guy at a busy high end shop. Sometime in the late '70s or early '80s, the owner purchased an Audio Technica stylus scope. This was sometime after the microline was introduced, I'm not exactly sure. It was an expensive piece, well over $1K back then. It was sold to dealers only and they're rare. The scope had a deck that could accommodate a cartridge and high intensity side lamps on goosenecks. The stylus type/wear chart that came with, taught me how to evaluate wear patterns. It can be a little tricky when there are obvious signs of wear and the customer is skeptical. So I would focus the scope and let them see for themselves, then show them the chart.
You really don't need a stereo scope. There are plenty of scopes with three objectives that go up to 400X. Above 400X the lenses get expensive or the field's edges get fuzzy. 400X is fine, you just have to get decent quality and a stage that goes down far enough. We used a hunk of modelling clay to hold the cart or stylus in place. You can get high intensity lamps externally. It looks like you already have that. The last pic of the Grace(?) was excellent and the wear is obvious. I'd send it to the retipper for a ruby/LC or micro. Now that I think about it, the AT scope might have been one of those with a black background. It didn't seem as lit up as your pics, but you don't need anything more than what you have now plus a little more magnification.
I tried net searches to find the AT instructions or chart, with no luck. The stereo shop is long out of biz. The Shure guide should be fine and it seems that you already have a good grasp of what's going on. One of the trickiest things about it is focusing on that tip at high power. The lens is right up next to the stylus. Once I saw someone trying to focus and crush a stylus. After you do a few of them you get a feel for where the lens is and it won't be a problem. Go around to the front and physically center the tip right on the lens and focus by backing off. That way you're safe, even if you have to do that a few times. You really don't need to invest a lot of money in a fancy scope, not for this. Most of it is knowledge. Use low power to look at color and polish. Look for cracks or gouges. High grade diamonds are clear. Industrial diamonds are black. You've already got it, you just have to refine it a smidge.
Regards, |
Hi Mike, I completely believe everything you say. Obviously your fastidious and very into records and I didn't mean to discourage. It was only that picture as evidence of AS or wear, I took issue with. Most of us here are a bunch of guys outside of our area of expertise. The exception is playing records. Luckily, J Carr comes around once in a while and explains things. There are mechanical and electronic aspects that most of us don't understand completely, or at all. Sometimes humor or sarcasm doesn't get through or isn't understood as such, in these posts. There are no smiley or frowning face thingies here to alert. But there's much to be learned. Raul has tried carts that I never heard of before I started reading, and I was in the biz when they were being made.
You must have really liked the Universe. Close to 2700 hrs is pretty damn good. My Monster Genesis 1000 is one of my all time favorites. It was also designed by Nakatsuka. I prefer it to the 2000 which had gold coils. The 2000 is more lush, but the 1000 is faster and more real sounding to me. Have you found a cart that competes or you like better than the Universe?
Regards, |
Tangency and AS are two issues that impact on each other. If we agree that skating is caused by the additional vector from offset, then tangency becomes a separate but related issue. After all, a pivoting arm is only tangent to the groove at two points on a record side. I keep referring to linear tracking arms, and their lack of skating. Many linear arms can not maintain perfect tangency 100% of the time, especially with records with off-center spindle holes. There is still no skating because there is no offset. When skating was first explained to me, back in prehistoric times, I was told it was because the arm/cart had inertia moving toward the spindle. Wrong!!
Because the one perfect setting for AS is impossible to achieve, we need a sensible way to find a satisfactory setting. There are 2 factors that effect AS, position on the record and stylus velocity. The technique of sighting your cart from the front is effective in ballparking. You can try this with a "normal" record, representative of your regular fare in terms of volume. If you haven't tried this, I think you'll be amazed at how revealing it is. A mono vocal record is often recommended to get a good center. If you set your AS for the worst case possibility, the loudest passages, then you'll have too much AS during quiet passages, so you have to find a happy median. IMO, too much is worse than too little.
All set-up parameters impact on each other and it's a mistake to think you can optimise one in isolation. Azimuth is one that that goes hand in hand with AS and has similar adjustments and consequences. Viewing from the front, if the needle is tilted so the top is going to the left or spindle, the right ch high frequencies suffer. That mono vocal record is very effective here as well. Not all styli are mounted perfectly in line with the cart body. It might look funny, but sometimes the whole thing must be tilted a little to have the tip straight up and down. If you're having trouble hearing it, get some kind of output level indicator, PC program, test record to help you. VTA/SRA is another setting that impacts. As you adjust one thing, the others come into focus.
The consequence of alignment error is the needle bouncing off the grooves at an odd angle. I hear mostly a phase distortion between channels. I'm not sure if phase is the right description. One channel is delayed with respect to the other, so the information at any instant in time is slightly off. I can only hear this if the error is greater than 2 or 3 degrees (I think). With a familiar set-up, I hear the difference between Stevenson or Loefgren A or B, especially at the beginning. Longer arms minimize this and VTA/SRA differences but have another issue, moment of inertia.
My apologies to most of you who know this stuff. Some people and many newbies seem to need a little advise. For the next installment: William Tell saves Sir Issac Newton and we all go flying off into space.
Regards, |
One thing I didn't describe well is alignment error consequences. The odd angle is in relation to the cartridge and cantilever. Although it's the tip that actually traces the groove, it's the movements of the cantilever that get the generator going. Alignment error has audible consequences. Time delay or phase error might not be the right description. I'm not sure what is.
Regards, |
Timeltel, Lewm, I wrote that as a practical guide for AS considerations, not as a physics lesson and repetition of everything that's been said. Apparently neither of you figured it out yet, because you're both only partially right. NO, centripetal force is not a factor. It is so inconsequential in this case, it really doesn't matter and any additional skate would be compensated for.
Vector 1) VTF causes friction and the groove pulls the stylus at 180 degrees to the (arm) pivot, or in line with.
Vector 2) Cart is offset to maximize alignment. This same friction/groove pulls the stylus at 180 degrees to the cantilever, or in line with offset.
Vector 3) 2 forces combine to cause skating.
Conical styli use VTF and have friction. If mounted on a pivoted arm with offset, there will be skating.
A stylus being other than tangent does NOT cause skating.
You're making more of this than it is. No need to reinvent the wheel.
Regards,
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Hi Raul, Do you have experience with any Coral cartridges?
Years ago I had an Adcom HOMC that I believe was made by them. The SAE 1000 is said to be there's also. I seem to remember something about a model 777?
Thanks, |
Mike, nice to read about your recent experience with AS and your arms. As per Raul's request, your post was an empirical description of consequences or benefits. I took it for granted that the goal is to get a proper image and center. Bass performance is also impacted because excursions between groove walls will be affected by side forces on the arm. There are programs available now (like Feickert) to see performance plots on your PC. You could also see azimuth at the same time. Someone on another former has the Feickert program and wound up using a mono record. I think David knows something of what's available and might be able to recommend one.
Regarding the theory behind AS: I really don't know if centripetal force is the primary cause. The arm swings in an arc and it is accelerating, so maybe it is. Then, is the additional force from offset a Coriolis force? [Joke]
Point is, it's moot as far as empiricists like I am concerned. I know that conical styli use friction to stay in the groove and are subject to the same considerations, possible less so than other types. BTW, a .2 x .7 has smaller contact area than most conicals. I don't think tangency has much to do with it. Why would tangency have an affect on these forces, would it negate friction, the primary force?
For practical considerations, adjusting AS, there are two primary considerations to take into account. If you adjust for the loudest passages or highest velocity on a test record, you'll have too much, most of the time. I find a mono female vocal, most useful to get a center image.
Regards, |
Prof, I just looked at the first file. It's 1980 confusing because cutterheads were calibrated in terms of VTA or cantilever angle. The standard changed from 15o to around 20o. Because of VTA variations in carts, SRA is really what counts. 2o forward of perpendicular or 92o is what's considered right for most modern records. For all records, this can vary by about 5o. Now they test VTA/SRA for intermodulation distortion and test signals of 60Hz and 4K, 4:1 ratio. You need an IMD tester and test record.
Regards, |
From physics class:
"Any motion in a curved path represents accelerated motion, and requires a force directed toward the center of curvature of the path. This force is called the centripetal force which means "center seeking" force. The force has the magnitude." Clearly in our case this force is friction and the direction is defined by the groove and the fixed arc of the arm. Also:
"Centripetal force is a force that makes a body follow a curved path: it is always directed orthogonal to the velocity of the body, toward the instantaneous center of curvature of the path." In this case the force is not what makes the stylus follow a curved path. That path is determined by the stylus and pivot position being fixed. That's why I have doubts if it really is centripetal.
"What causes the (centripetal) skating force is the fact that conventional pivoted tonearms are never tangent to the groove wall. Because of that there is always a force vector generated that is in a direction determined by the angle between tangency and the actual angle of the tonearm wrt the groove." IMO this is totally an unequivocally wrong. 1)There are two points along the arc that are perfectly tangent. Does skating stop for those points? 2) Friction keeps the tip in the groove which determines direction. Is it dependant on alignment or being tangent, or can there be friction and forces regardless?
"The forces exerted by the groove wall would be present for any and all styli riding in any tonearm, even linear trackers. (I start from the fact that in an air-bearing linear tracker, that force is the only force acting on the stylus tip, yet we say that linear trackers do not induce a skating force.)" Most linear trackers AFAIK, use VTF and friction to keep the stylus in groove. Your point supports what I'm saying. The only reason a pivoting arm and skating could be considered centripetal is because the path of stylus is curved, the force is toward the center, and it's accelerating.
It was stated by physics type people that the vectors of force derived from friction, by the stylus, is what causes skating. Centripetal force is usually applied to spheres orbiting a larger body, or twirling a ball on a string. It would also apply to a car spinning out on a curve so maybe it applies. Perhaps if you find the answers to these questions, we'll know.
Does a pivoting arm with no offset, skate?
If a linear arm is not tangent at some point, does it skate at that point? Why, because of lack of tangency or no offset?
Regards, |
That's what I was talking about regarding skating. The force will vary depending on position and stylus velocity. I think the idea is to find a setting where you get a centered cantilever at moderate velocity at different points on the record. Most AS controls are calibrated for a percentage (15 to 20% ?) of VTF. One problem is that old spring loaded controls can be way off. Also, modern stylus profile might require greater AS. The Wally Tractor sounds like a cool device. Sighting from the front at different positions on the record is also effective. Looking at output levels on an electronic device is good. Because there is no perfect setting for all occasions, I try to find a position that sounds centered with a mono female vocal with a small band behind her. This is like my normal fare only I don't listen to all that many vocals. I can't help but to sight the cart from the front. If you can get in that position you'll be amazed at what you'll see. With even lighting and being directly in front, the angle of the cantilever in relation to the cart body is obvious. Do this at three places on the record and it will get you 90% of the "perfect" setting. May the anti-farce be with you. Sorry.
Regards, |
Lew, IMO the most elegant and concise description already supplied by J Carr:
**What causes skating forces is the fact that, with offset-angle tonearms, the LP groove pulls the stylus in two vectors at once. One vector is from the stylus to the tonearm pivot. The second vector is along the offset angle.
These two vectors synthesize to produce a third vector that pulls the stylus inwards, toward the platter bearing. It is this third, synthesized vector that we call "skating force" or "side force".
Since skating forces are comprised of the drag on the stylus from the LP groove, they vary depending on stylus profile and groove cutting levels, and from what I have seen, the skating forces also vary according to the instantaneous groove radius. (If you can find an Orsonic SG-1 "Tonearm Side Force Checker" it will allow you to plot the curves).
If I recall correctly, if you can manage to cancel out the groove amplitude-dependency component (by using a constant-amplitude test LP), the side force curve ends up looking fairly similar to the tracking error curve for the particular tonearm alignment that you have chosen.**
I think offset and not overhang is the cause. If the offset is 23 degrees, wouldn't the arm be tangent when it gets 23 degrees away from the null? (not that it matters) If you offset a cart on an arm with no overhang, there would still be skating.
I think we can agree that skating exists, regardless of theory. We all agree that it's friction pulling the stylus in 2 directions at once? Both those directions are away from the pivot or stylus, not exactly toward the spindle.
Regards, |
correction: I should have said, Both those directions are away from the pivot or cantilever line, not exactly toward the spindle. |
Lew, The basic vector is tangent to the groove in a clockwise direction. This is further complicated by the pivot/offset angle thing. Please read the last paragraph under Arm Systems (below). I think that's it in a nutshell. Beyond that you'll have to consult your friendly neighborhood physicist. Further than this is beyond my current understanding. Maybe the Prof can enlighten us further. I don't know. At this point I'm more interested in results, measurements, and techniques for optimising sound.
http://en.wikipedia.org/wiki/Phonograph#Arm_systems
Regards, |
Timeltel, I said I wasn't sure about CENTRIPETAL force. I still don't see tangency or lack of, as causing skating. Must you be so emphatic?
I'm done with this. Please address further comments on this subject to someone else.
fleib |
Timeltel, You quote me out of context, not even a complete sentence, and change the meaning. It wasn't a command, it was a request. You omitted the word please.
""address further comments on this subject to someone else." is not exactly what I said. I believe that you also attributed statements to the wrong person once or twice. I don't want to hassle about this nonsense. I'm interested in concepts or finding out about specifics, like carts I've never heard. If you're not sure who said something, perhaps it would be more productive to talk about the concept, rather than who said it. This is just a suggestion. I see you're an experienced poster and not a noob. You're also a skilled writer and that's why I sometimes find your approach objectionable and counterproductive. If I made a reference/joke that you find snide, it wasn't intended to make fun of you and I apologize if you took it that way. Funny, I feel the same way.
I have a working knowledge of AS and and basic understanding of the forces involved. What would interest me is techniques for modifying arms for more precise application of AS, especially for diff parts of the record. The Unitrac arm is designed to be mounted so the pillar (not pivot) is 56 degree angle between spindle and rest position. If not, AS calibration is affected. Isn't that interesting? It really doesn't matter if centripetal force is responsible, or you need Susskind to explain. It would be nice to know, but not as important to know whether it's an earthquake shaking the house or a bus going by.
Regards,
|
Sometimes a slightly skewed cantilever can be corrected by using max VTF and corrective AS, in opposition to the skew. I've successfully done this a couple of times. My results indicate you must catch it early, before it gets extreme. Sometimes it doesn't work. I'll only suffer with that on few old records. You can also physically move the cantilever with your finger or plastic tool, to see how bad it is. With hi cu carts sometimes a small angle is really no problem or easily corrected.
Timeltel, maybe we can put this behind and move on?
Regards, |
Superglue or even epoxy can be cut with a razor or sharp blade like a scalpel. If applied sparingly, in a manner as described, there should be no problem removing the stylus holder/assembly. This would be very different from using contact cement on the plastic/metal interface. You would likely have to destroy the plastic holder to remove it. In either case there would be remnants of glue on the body. If three small drops are used it might not be a problem.
I use tack and it seems to work well. In the case of Stanton/Pickering styli, the tack can be used to fill up or partially fill the hollow plastic and damp it.
Regards, |
Timeltel, Lucky for you the XV-15 750E is not the same generator as the 681. The 750E is a MM and the 681 is a MI which happens to have 930mH inductance. Perhaps you meant stylus substitution/body style? I suspect you could get a replacement substitution like a Jico vivid line for around $80, but I'm not familiar with the number substitutions. It looks like a Pickering 3000 through 7500 (Stanton D81), but I don't really know. BTW, very high quality rubber bands are available at the supermarket in the produce section. They come wrapped around bundles of broccoli and asparagus. They might be a little long, in which case you could get one of my audiophile rubber band cinches for only $300.
On a more serious note, I find this tape ball business disconcerting. I wonder if the package from Mexico was inspected and tampered with? Just a thought.
Regards, |
I thought it was common knowledge that Stanton and Pickering were sister companies. They shared the same technology and stylus substitutions are prevalent between model lines. Some time ago I posted that I'm using a Pickering D3001 stylus on my 980, which also takes the Stanton D81 (881) stylus. Any Pickering D3000 through 7500 can be substituted for a D81. Indeed, the 980 LZX cart is identical to the Pickering 7500 - not just in stylus, everything. However, this is not the case in most stylus substitutions. It's like AT. I can put any number of different styli on my Virtuoso, like a 3400, 95, 92ECD, 3472 and variants etc, but the carts themselves (bodies/generators) are different. BTW, I'm still using the P-mount styli on my Virtuoso and getting better results than the 95 variants. The cantilevers are thinner so lower tip mass. VTF is 1.25 to 1.5g. I'm using low mass arm - Sonus Formula 4 and Unitrac. |
Hi Lew, Yes, the orig stylus for the 980 Is the D98, but the D81 is interchangeable, so are the other Pickering styli I mentioned. I don't know if there is any difference between a D81S and a D98S, possibly compliance or some qualitative difference? The Pickering 7500 seems to be identical to the 980 LZ. I've compared specs with a couple of guys that have the 7500, including David. Apparently there was a predecessor, the XLZ-4500S. It has a stereohedron and the 7500 has a stereohedron II. I like the Pickering stylus holder better than Stantons.
I'm rather new to the Stanton line, this 980 is my first. I bought it NOS from Kevin at KAB a few years ago. He's the one who told me about stylus possibilities. Matter of fact, when I bought it I also got the D3001 (.2 x .7) stylus to go with it. In the old days I didn't like Stantons, specifically the 681 which is what I usually heard. This dislike continued until I heard the 881. By that time I was into LOMC. I noticed the listings in the cart database for the 500 series. I think the problem with all these Stanton/Pickering is cheap styli and holders.
Regards, |
Montepilot, I agree with you regarding detail and resolution. There's no disputing your results. There's a big movement lately about preferring musicality over detail, but I don't think it's an either/or proposition. Sometimes it might seem that way mostly due to equipment limitations. But many people seem to genuinely feel that too much detail goes beyond that from a live event. So it brings up the question, if you were in a club or concert would you hear those details of Ella's voice or the rice on the drum head. Personally, I think the point is moot. Those details are on the recording, regardless.
Regarding ICs in the phono stage. Raul doesn't know what he's talking about, although he's entitled to his opinion. The fact of the matter is that discreet components can't do what good ICs do in many areas of performance. Having a million parts all connected with wire or traces on a board is only superior because of old school prejudice and inferior designs using ICs. Most designers don't know how to effectively regulate ICs. I haven't heard the F-115, but seeing pictures of Samuels board, it looks like he might know what he's doing. Nevertheless, it doesn't change your results.
Raul, I've reached the conclusion that Soundsmith is right. You're a preamp manufacturer masquerading as a hobbyist. Even if your production is limited and not generally available, you've offered it for sale. Hasn't it been going through revision? Planning to start up production? What the hell is going on with that tape ball cartridge, are you dishonest as well? |
Raul, I wasn't going to post on this thread until the tape ball incident was cleared up, but I'm compelled to comment. I didn't design the phono stage that you thought, and I have no financial interest in any currently manufactured product. I suspect that you, on the other hand, are using this platform to launch commercial products, namely a preamp, tonearm, and possibly a cartridge. I don't know the extent of this but I do know that you have offered the preamp for sale.
" If the 103 is your champion certainly you deserve it that king of performance level and nothing more. "
While I don't see that comment as arrogant, it is nasty and mean spirited. If that opinion is so absurd, why the invective about what someone deserves? Isn't this thread intended to enlighten and inform? It's obvious to me that you're stalling to maintain interest. That's why you haven't named the mystery MC cart. How long before a refund in the tape ball incident, and why no comment? You're looking to buy more carts while this is unresolved?
You can no longer dismiss my comments about preamps because I designed AHT. I didn't. The fact remains that ICs are superior in some areas of performance. I noticed that your mystery MC revelation came right on the heels of a redesign of your MC stage. Why is your system down now, redesigning the MM section? You might have tried many carts, but your opinion isn't the last word and I don't defer to it, especially considering that your preamp is probably second rate. How many other MC will now give superior performance? Need more time while the MM section catches up? Why are you turning this into a soap opera?
Regards, |
Raul, I've seen posts on this thread about sellers who were suspected of taking money for defective cartridges. However this turns out, it is unseemly for you to be named as one. Although this is not a tribunal, people reading this have only heard one side of the story. I naturally assumed that this would be resolved in an equitable manner, whatever the outcome or reason. If someone has a bad experience buying a cart from whomever, we all read about the eventual outcome or circumstances. This is no different.
Regards, |
Nandric, didn't you have 2 Virtuosos re-tipped, 1 with aluminum and 1 with boron? If I remember correctly you said that they sounded similar. Any updates on that?
FWIW on another forum a fellow who makes carts, Blue Angel, said that he has bags full of old carts that were given to him and he has yet to see a dried out rubber bushing. Many were over 30 yrs old. They've been using synthetic rubber for a long time.
I concur with everything Dlaloum said about cantilevers and performance. If anything, it's even more complex than what he stated. All carts, MM and MC have a naturally rising high end. It's damping that tames it and also causes amplitude/phase anomalies in the treble. MMs tend to use more damping than MCs and inductance in the output will lower the high frequency resonance, making things worse. Adding shunt capacitance will roll off the extreme treble and usually make it brighter right below that point. I can't help thinking that loading some carts at 100K and adding 200 or 300pF + cables, is the wrong approach. Inductance is the Achilles heel of HO carts. I've read here that some carts are used with their tails up in the air or down low. IMO this is to compensate for improper loading. SRA should coincide with the record, not to correct a weird load.
Regards, |
Hi Timeltel, The only Stanton I ever owned is the 980LZ that I currently have. In the mid '80s I had a Pickering XSV-4000 (I think it was) that I didn't keep very long.
**Stanton was (according to others) also involved in aerospace metallurgy, what appears to be a cheap alu. cantilever may not be so simple after all.** Does this somehow make it a superior aluminum alloy? The cantilevers are relatively short which is a good thing, but for some prices I've seen for orig replacement styli, you could have custom ones made. One advantage with most MM/MI carts is replaceable stylus. Voicing a cart is a complex issue and has to be done on an individual basis, but now there are more options for cantilever/tip combinations. Perhaps experimentation would yield something beyond the limitations of alum/stereohedron. With your knowledge of cart parameters and cantilever/tips, perhaps you can tell us empirically, what combination is best for a particular cart.
Regards, |
Nikola, I don't understand your answer. You still hear no difference between cantilevers? This isn't a legal matter - no need to give an evasive answer. The anecdote about a highly publicized defectively glued stylus is meaningless, but amusing. I can picture Mikey Fremer checking SRA with his microscope, good for him! Does the stuff about metallurgy and alchemy mean that you think there is no difference?
Lew, I can't find the dimensions of Soundsmith contact line. The Grace F9 diamond is .2 x .8 mil? There's probably only a little difference in the minor radius but you should get more vertical contact. A guess - slightly more detail, esp in high freq and greater tip longevity.
Regards, |
Phase linearity as in phase vs amplitude, is the biggest factor in imaging capability in a phono cart. Generally, the higher the primary high frequency resonance, the better phase linearity and imaging. This obviously isn't about the recording. It's damping the motions of the cantilever that causes phase non-linearity. MM/MI carts tend to be more heavily damped and often have a lower high frequency resonance. Of course there are notable exceptions.
Regards, |
