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Numark TTUSB tonearm adjustment
rocket_pc
post Dec 11 2009, 22:03
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I have first browsed the wiki for this, though only a few minutes. My question is about adjusting the tone arm on the Numark TTUSB. Can anybody tell me where there are instructions on adjusting the counterweight on the tone arm of the Numark TTUSB and adjusting the anti-skate mechanism?

I got the turntable yesterday. The instructions in the operator's manual is insufficient, with only a few sentences on the subject that seem very ambiguous to me.

The manual says,
QUOTE
...there should be a feeling of weight and resistance when the head shell is raised and lowered. Begin rotating the counterweight clockwise (away from the pivot point) until the weight and resistance feeling is gone. If done properly, the tone arm will pivot with very little resistance back and forth indicating that there is exactly 0 grams of stylus pressure. With the counterweight in its new position further away from tone arm pivot point, grasp the scale ring of the counter weight and rotate it until "0" is in the vertical position. Finally, rotate the counterweight (and scale ring) counter-clockwise (towards the pivot point) until the desired amount of weight is reached. If the scale rotates 360 degrees beyond the zero point, the new scale ring reading should be added to 3.5.

I don't understand these instructions at all. I remember seeing somewhere last month, when shopping for this, mention of some website or other with instructions on adjusting the tonearm and antiskate functions.

Thank you, in advance, for your attention on this subject.

Don

This post has been edited by greynol: Dec 11 2009, 22:04
Reason for edit: Please use the default font. Placed quote in the proper container.
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DVDdoug
post Dec 11 2009, 22:47
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I don't have that turntable, but the instructions sound fairly "standard".

First, the idea is to "calibrate zero" (with the cartridge installed). So, you adjust the counterweight 'till the tonearm is perfectly balanced (zero tracking force).

Then you set the dial (without moving the counterweight) to read zero. You might have to hold the counterweight to prevent it from turning at the same time... After calibration, the weight and dial should be moved move together.

Then, you rotate the counterweight and dial together to set the actual desired tracking force. (per the specifications supplied with the cartridge.)

Then, you set the anti-skating to match the tracking-force adjustment.

QUOTE
If the scale rotates 360 degrees beyond the zero point, the new scale ring reading should be added to 3.5.
One full-rotation is 3.5 grams, and at this point the dial will read zero again. So, if you need more than 3.5 grams (probably not), you need to make a calculation.

P.S.
You probably didn't realize that you can turn the indicator dial without also rotating the counterweight.

This post has been edited by DVDdoug: Dec 11 2009, 23:01
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rocket_pc
post Dec 12 2009, 23:12
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Thank you for the reply, DVDdoug. I didn't see the reply until now, because there was no email alert.

The way I understand this, the tonearm is "balanced" when it floats (above the platter or off the side of the platter?), and then the dial is set to zero. That would imply that the 3.5 - 5 turns "weight" is for reaching the surface of the record. I don't believe that, because I think that "weight" is the amount of pressure on the surface of the record. There is some variation in the thickness of records, I believe. The earlier records (1950 to 1960s) may have been thicker.

With the very common transflexive surfaces of laptop mousepads and of pdas, these expesive turnables aren't as high tech as they claim. An high tech turntable could read the pressure on the record surface, with existing computer technology.

Anyway, I am still uncertain on how to calibrate this tonearm. I'll look up this thread in the morning, if I don't get an email alert.

Thanks again for your attention on this subject.

Don

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rocket_pc
post Dec 13 2009, 05:30
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Thinking about this, once again, adjusting the tonearm/stylus has nothing to do with "balancing." The arm may be balanced at 1/2 inch above the surface of the record, obviously of no use to playing the record. I believe the tonearm should be lowered to where it barely makes contact with the surface of the record, then secured at that point, and then the dial set at zero. Turning the dial to 3.5 (whatever that is) would then lower the needle deeper into the surface. What is your opinion about that?

Thanks for trying to help me on this problem.

Don
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MichaelW
post Dec 13 2009, 06:47
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QUOTE (rocket_pc @ Dec 13 2009, 16:30) *
Thinking about this, once again, adjusting the tonearm/stylus has nothing to do with "balancing." The arm may be balanced at 1/2 inch above the surface of the record, obviously of no use to playing the record. I believe the tonearm should be lowered to where it barely makes contact with the surface of the record, then secured at that point, and then the dial set at zero. Turning the dial to 3.5 (whatever that is) would then lower the needle deeper into the surface. What is your opinion about that?

Thanks for trying to help me on this problem.

Don


The dial has calibrations, representing force in grams--you set to "3.5" on the dial.

First, balance the arm: it will float. Keeping the counter-weight still, turn the dial until it reads zero.

Then, turn the dial and counterweight together until the dial reads "3.5"

The needle end of the arm will, of its own accord, drift down until it rests on the platter, surface of the record, or whatever it meets, where it will exert a force of 3.5 grams, which is what you want.

These numbers don't control the height of the needle end of the arm: they represent (once the thing is adjusted) the extent to which it is out of balance, measured in grams of force at the needle.

Hope that helps.
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rocket_pc
post Dec 13 2009, 21:24
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Thanks for the reply, Michael. Okay, now I understand what the purpose is in the tone arm weight adjustment. There were several posibilities. The instruction manual so ambiguous, I wouldn't know. Anyway, the tone arm weight adjustment may be simple.

Okay, what about the anti-skate dial? Do I leave that alone, or is there an adjustment for that also? I am confused about the concept of the antiskate function, also.

The website, Knowsy.com, says that the purpose of antiskate is to center the needle in the groove. Knowsy.com says that each side of the groove is for a speaker of the stereo. From my recollection, there is no explanation there on adjusting antiskate. Opposing this, is a utube demo stating that antiskate purpose is to keep the tone arm from sliding accross the record platter <http://www.youtube.com/watch?v=wzQjuDqv0vY>. I'd like to understand the basic concept of antiskate, one way or the other.

This is very important to me, because I am going to convert a collection of Christmas vinyl records to digital, and then burn them on expensive media, probably involving many hours.

Thank you for your help.


Don



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MichaelW
post Dec 13 2009, 21:28
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I can't give a reasonable explanation of anti-skate, but I think if you do a search on this site, you'll find useful stuff. The person behind knowsy has been a visitor here, so there might be something in one of his threads.

Happy hunting.
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pdq
post Dec 14 2009, 00:11
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As the record turns, the needle dragging in the groove produces a force due to frictiion. Because the tone arm is at an angle with respect to the groove, part of this force is exerted as a sideways force, or skating force. This force tries to draw the needle toward the center of the record. If there were no anti-skating correction then this would cause the needle to press harder against one side of the groove than the other.

Since the frictional force is proportional to the tracking force (the downward force of the needle against the record) the skating force is also proportional to this, which is why the skating force needs to be adjusted with the tracking force.
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rocket_pc
post Dec 14 2009, 01:47
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Thank you for your replies. Michael, the google searches of the past couple weeks have been cluttered with subjects of the "DJs". I don't believe these are radio djs, but rather disco djs whom deliberatly abuse their records - and turntables, scratching the records, dragging the turntables... I've seen a few new sites on a search a moment ago, and I'll see what their about. According to Knowsy, Hydrogenaudio is a very authoritive forum of "audiophiles".

PDQ, are you saying that I should adjust the antiskating at the same time that I am adjusting the counterweight? How do I make this adjustment?

Thanks.


Don

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Axon
post Dec 14 2009, 04:19
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Antiskate is complicated, and different instructions (advocated by different people) will give widely varying results. There is no "right" antiskate setting: it varies from record to record. If you get within 50% of the optimum value for each particular record you play, you're doing pretty good. I doubt anybody gets closer than 20%.

The "normal" (and easiest) instruction is to set the antiskate dial equal to the vertical tracking force setting in grams. If you don't have a spherical stylus, add 20-50% to the VTF setting.

A more complicated method is to purchase a test record with a tracking test on it, and set the antiskate so that the level of distortion in both channels is equal. But there are good reasons to believe that this may not be an accurate way to align for optimum tracking ability, or lowest distortion, for "real" music records.

If you have a blank record (a side without a groove cut on it), and if you have a spherical stylus (which you do), you can set the VTF to 40% higher than you normally set it, set the needle down on the spinning record (being extremely careful to lift the arm quickly if it spins off the record). Then adjust antiskate so that the arm is roughly stationary at the center of the record, and set the VTF back to the normal value.

With some cartridges with very high compliance, you can observe the bias force skewing the cantilever left/right, and the antiskate force likewise. You could use this to set the antiskate so that, when looking at the cartridge from the front, the alignment of the cantilever when playing a record is the same as when it is lifted off the record. However, you almost certainly don't have a cartridge for which this will work.

This post has been edited by Axon: Dec 14 2009, 09:02
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cliveb
post Dec 14 2009, 09:49
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QUOTE (pdq @ Dec 13 2009, 23:11) *
As the record turns, the needle dragging in the groove produces a force due to frictiion. Because the tone arm is at an angle with respect to the groove, part of this force is exerted as a sideways force, or skating force. This force tries to draw the needle toward the center of the record. If there were no anti-skating correction then this would cause the needle to press harder against one side of the groove than the other.

Actually the stylus should not be at an angle with respect to the groove. (Of course on a pivoted tonearm, most of the time it is *slightly* out of alignment). The source of the sideways force is due to the overhang. A pickup arm with zero overhang doesn't generate any sideways force.

So, you may ask, why have an overhang? Because it improves the geometric alignment of stylus to groove over a wider portion of the LP side. This benefit outweighs the downside of needing to add antiskate. (Ever noticed that linear tracking tonearms have no overhang?)

The best way to set antiskating is to start at or slightly above the tracking force, then adjust by ear. As Axon says, it's very difficult to get it right for every LP, so don't stress too much about this.
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Axon
post Dec 14 2009, 11:40
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Adjusting by ear means adjusting both the tracking distortion and the distortion resulting from the varying pressure applied to each groove wall. The latter is intimately tied to antiskate but the former has nothing to do with it and changes over the course of the record.

It means explicitly not optimizing antiskate for maximum tracking ability/lowest change of falling out of the groove.

There are good reasons to follow either approach - but realize that a) the two goals are to to a large degree mutually exclusive, and b) adjusting by ear has its own specific potential sources of bias.
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rocket_pc
post Dec 14 2009, 19:47
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I could just "adjust by ear" - listen to a record through headphones to hear if there is a stronger sound in one ear over the other, and adjust the antiskate accordingly. I don't have the turntable connected to a stereo. But if I did, I could use volume controls independently on the speakers, shutting one off, and then the other to hear if speakers are at the same volume. I may have headphones somewhere that have sliders on them. And use a record that hasn't been played much, as there could be an imbalance due to wear by turntables that didn't have antiskate functions.

Don


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cliveb
post Dec 15 2009, 09:43
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QUOTE (rocket_pc @ Dec 14 2009, 18:47) *
I could just "adjust by ear" - listen to a record through headphones to hear if there is a stronger sound in one ear over the other, and adjust the antiskate accordingly. I don't have the turntable connected to a stereo. But if I did, I could use volume controls independently on the speakers, shutting one off, and then the other to hear if speakers are at the same volume.

Incorrect antiskate doesn't affect perceived volume much at all. What you're aiming for is equal levels of distortion on the two channels. With a test record it's fairly straightforward (although the optimum antiskate will be different at the outer and inner grooves, so you have to pick a compromise). But with a music LP, it's pretty difficult to judge when the two channels have equal levels of distortion. Your best bet would be something like a solo piano piece (use the loudest part for your tests).
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rocket_pc
post Jan 10 2010, 08:59
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Thank you for your reply, cliveb. I hope you understand my absence - Christmas holidays... Didn't get the xmas LPs converted to digital, either. Was out of time, last week before Christmas, to get the recording system in order.

Anyway, I would like to ask about the "blank record" that was mentioned here, before this thread expires. Is there a place that I can purchase a blank record like this, and stylus/anti-skate instructions?

Thank you for your help on this subject.


Don

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cliveb
post Jan 10 2010, 10:52
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QUOTE (rocket_pc @ Jan 10 2010, 07:59) *
Anyway, I would like to ask about the "blank record" that was mentioned here, before this thread expires. Is there a place that I can purchase a blank record like this, and stylus/anti-skate instructions?

The force that draws the stylus towards the centre of the record is due to the pressure exerted by the groove sidewall. So a record with no grooves doesn't help. If you're serious about setting antiskate correctly, you need to get a test record with high level tones cut at the outer, centre and inner parts.
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rocket_pc
post Jan 10 2010, 12:26
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QUOTE
The force that draws the stylus towards the centre of the record is due to the pressure exerted by the groove sidewall.


cliveb, You said that "The force that draws the stylus towards the centre of the record is due to the pressure exerted by the groove sidewall." Yes, but the turntable has an antiskate function that keeps this from occurring. Could you tell me where I can find the blank record or special record, that you mention, for conducting this test, and a reference for carrying out this test?

Thanks.

Don

This post has been edited by JensRex: Jan 31 2010, 13:36
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cliveb
post Jan 10 2010, 15:08
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QUOTE (rocket_pc @ Jan 10 2010, 11:26) *
cliveb, You said that "The force that draws the stylus towards the centre of the record is due to the pressure exerted by the groove sidewall." Yes, but the turntable has an antiskate function that keeps this from occuring. Could you tell me where I can find the blank record or special record, that you mention, for conducting this test, and a reference for carrrying out this test?

Perhaps I didn't explain things clearly enough. By "blank record" I took you to mean one without any grooves cut in it. This won't work. You need to get a test record with a signal cut into the grooves designed for this purpose. I personally use a test record called "HiFi Sound HFS75". One nice feature of HFS75 is that it has antiskating cuts at the outer, centre and inner portions of the record, allowing you to find the best compromise. (The ideal amount of anti-skating varies across the record). However, I don't believe HFS75 is available any more. HiFi News do a test record, but I'm not sure exactly what cuts it has. http://www.needledoctor.com/Brand-Stores/LP-Test-Records has a few test records listed. One of them, "Ultimate Analogue Test LP" looks to have some useful stuff on it (but only one antiskating test cut, at the outer edge of the LP).
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rocket_pc
post Jan 10 2010, 16:41
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QUOTE
However, I don't believe HFS75 is available any more.


Maybe its on an online auction somewhere. Or I'll just look up the others you mentioned.

Don
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rocket_pc
post Jan 12 2010, 06:18
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Hi cliveb, Thank you for your reply. I've got appointments until after Wednesday. If I have any spare time, I'll look up the very good faq and knowledgebase that I noticed you have.

I looked up the links and the product that you mentioned (HiFi Sound HFS 75). It was priced at $44.99. Isn't that kind of high? I was thinking of $15 - 20, plus shipping. If I can get this record in used condition, could that affect the test results? Also, are the new test records any different or better than the test records manafactured several decades ago? (I noticed one manufactured in 1969!)

Also, a very important question: what is the very best test record? If I am going to spend any time on this, I would like to get the very best quality results.


Thank you for your time and attention on this subject. Re on Thurs.


Don
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cliveb
post Jan 12 2010, 09:34
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QUOTE (rocket_pc @ Jan 12 2010, 05:18) *
I looked up the links and the product that you mentioned (HiFi Sound HFS 75). It was priced at $44.99. Isn't that kind of high? I was thinking of $15 - 20, plus shipping.

Test records do tend to be a bit pricey these days. Probably because they are now a niche product, selling in much lower volumes than they used to.

QUOTE (rocket_pc @ Jan 12 2010, 05:18) *
If I can get this record in used condition, could that affect the test results?

Very possibly. It depends how the record has been treated. If it's been played on a turntable that had severe mistracking, then it will be damaged. And a simple visual inspection won't tell you whether that has happened. I personally would never buy a used test LP.

QUOTE (rocket_pc @ Jan 12 2010, 05:18) *
Also, are the new test records any different or better than the test records manafactured several decades ago? (I noticed one manufactured in 1969!)

I suppose in principle there may have been some technological improvements in cutting equipment since the 70s, but whether that is taken advantage of on newer releases is anyone's guess. I seem to recall reading that the HiFi News test record has some distortion actually recorded into it, so if you're looking for top notch results then it's probably to be avoided.

QUOTE (rocket_pc @ Jan 12 2010, 05:18) *
Also, a very important question: what is the very best test record? If I am going to spend any time on this, I would like to get the very best quality results.

I couldn't say what the "best" test record is. What I will say is this: You're using a Numark USB turntable. There's a limit to the quality of signal you can get from it. There are test records out there that cost more than the price of a genuinely decent turntable. If you're prepared to spend serious money getting your transfers right, invest it in (i) a better turntable (avoid USB and DJ types); and (ii) a vacuum cleaning machine (eg. Nitty Gritty, VPI, Moth, etc).
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Arnold B. Kruege...
post Jan 12 2010, 14:09
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QUOTE (rocket_pc @ Jan 12 2010, 00:18) *
I looked up the links and the product that you mentioned (HiFi Sound HFS 75). It was priced at $44.99. Isn't that kind of high? I was thinking of $15 - 20, plus shipping. If I can get this record in used condition, could that affect the test results? Also, are the new test records any different or better than the test records manafactured several decades ago? (I noticed one manufactured in 1969!)


Check eBay. I ve obtained several from there with good results.

Test records seem to be things that many people buy and rarely if ever use.

QUOTE
Also, a very important question: what is the very best test record? If I am going to spend any time on this, I would like to get the very best quality results.


I'm unsure what the best test record is, as they all have faults.

Some of the CBS Labs discs amd most other legacy are probably pretty competitive with modern discs because not much has changed in LP cutting technology in the past 20 years.

The Shure trackability discs are classics.

Some of the Stereo Review test records were actually pretty credible.
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rocket_pc
post Jan 13 2010, 00:30
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There shouldn't be too much wear from testing, with probably only an hour or so use to conduct the test, but if the owner didn't put the record back in the sleeve to get scratched up. Also, some material things become brittle with age. If that was the case with vinyl, all of our old records would be worthless.
So, on Thursday, I'll start searching for the HiFi Sound HFS75, CBS Labs discs, Shure trackability, and at Stereo Review.

Thank you for your help. Hopefully, I can bring out the best in the vinyls I have.
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Axon
post Jan 13 2010, 00:31
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The Ultimate Test LP is also worth looking at, and is almost certainly the best test record currently in production.
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cliveb
post Jan 13 2010, 10:49
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QUOTE (rocket_pc @ Jan 12 2010, 23:30) *
There shouldn't be too much wear from testing, with probably only an hour or so use to conduct the test

General wear & tear due to prolonged use is not the issue with buying a used test LP.

The problem is that test LPs are generally used to set up tracking force, antiskating, etc. And while doing this, it is very likely that some degree of mistracking will occur. Mistracking can permanently damage the LP grooves - just one instance of severe mistracking can trash an LP. And by their very nature, test LPs are the ones most likely to have been severely mistracked.

If you buy a used test LP and everything works beautifully, then you're OK.

But if you buy a used test LP and can't get decent results, it doesn't tell you anything. It could be that your turntable is badly set up, or it could be that your turntable is fine and is faithfully reproducing the damage caused by previous users.
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