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Topic: cart set up, distortion (Read 5654 times) previous topic - next topic
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cart set up, distortion

I've had time off so I'm back messing with my turntable...

I'm trying to set up a AT 440MLa on a AT PL120 turntable.  I'm using a Hi Fi News test LP as well.  I've got the cartridge aligned about as best as I can get it using the two point method that's printed on the protractor which came with the LP. 

On the bias setting bands on Side 1 of the LP I can pass the first two (300 HZ tone at 12db and 14db) without any distortion/buzzing but after that I get buzzing in the right channel regardless of what anti-skate setting I'm using.  The cart's tracking force is set to 1.8g, the maximum recommended range. 

On side 2 there are 3 "trackability" bands (300 HZ tone at 15db) spaced out at the beginning, middle, and end of the record.  I have a small amount of right channel buzzing on the beginning band, no buzzing on the middle band, and buzzing at the end band.

No matter what I do I can't seem to get this fixed.  Is 1.8g of tracking force enough?  Could the cart not be aligned correctly?  (Speaking of which--with the two point system, if the cart is in alignment on the first outer point but not the second, do I move it forward or backwards in the headshell?  Another thing alluding me...)  Could overhang be an issue?  The front of the cart extends somewhat beyond the end of the headshell, but I have no idea if that's right or not.  Would adjusting the VTA of the tonearm make a difference (it's at 0mm now)?

...Sigh.  So this is a lot for anyone to answer, but I appreciate any responses.  Thanks.

cart set up, distortion

Reply #1 –
Use Conrad Hoffman's tonearm alignment generator, I'd trust it a lot more than the one that came witn HFNRR: http://www.conradhoffman.com/chsw.htm

You shouldn't need to go so high on the VTF, and besides, the mechanical tracking force gauges are often a little inaccurate, so you might be 0.1g too heavy on top of that. You might want to go at the recommended VTF (1.4g?) or slightly above, unless you notice something is definitively fixed at a higher VTF.

Set the VTF after you align the cartridge. During alignment, set it as low as possible. (this is kind of a recent innovation that's been thrown about on vinyl engine, although there is not a whole lot of evidence backing up its usefulness.)

Antiskate is kind of touchy; I never really see much of a trackability difference on some carts no matter what I set antiskate to. This might reflect the high tracking ability of those carts. I'd just set it to 1/2 to 3/4 the tracking force by default for now, see how HFNRR handles, then tweak as desired.

VTA should not be a problem as long as the tonearm appears level.

Be absolutely sure the tonearm height adjustment is locked and secured, the cartridge stylus assembly is firmly mounted, etc.

cart set up, distortion

Reply #2 –
Maybe your cartridge simply can't handle these 12-15dB signals.  Do the instructions say that all cartriges should pass this test? What are the instructions with the test record?  I assume these levels are designed to push the limits of the stylus/cartridge, and find the level at which mistracking occurs. 

Does it say what the decibel level is calibrated/referenced to? (i.e. Is 0dB the "typical" maximum level on an LP, and these are +12 dB above that?)  Is the test level higher than what you're hearing on a normal record?

Is this a new test record, or is it possibly worn out and damaged (from previous mistracking)? 

cart set up, distortion

Reply #3 –
Quote from: yousuffer on
I've had time off so I'm back messing with my turntable...

I'm trying to set up a AT 440MLa on a AT PL120 turntable.  I'm using a Hi Fi News test LP as well.  I've got the cartridge aligned about as best as I can get it using the two point method that's printed on the protractor which came with the LP. 

On the bias setting bands on Side 1 of the LP I can pass the first two (300 HZ tone at 12db and 14db) without any distortion/buzzing but after that I get buzzing in the right channel regardless of what anti-skate setting I'm using.  The cart's tracking force is set to 1.8g, the maximum recommended range. 

On side 2 there are 3 "trackability" bands (300 HZ tone at 15db) spaced out at the beginning, middle, and end of the record.  I have a small amount of right channel buzzing on the beginning band, no buzzing on the middle band, and buzzing at the end band.

No matter what I do I can't seem to get this fixed.  Is 1.8g of tracking force enough?  Could the cart not be aligned correctly?  (Speaking of which--with the two point system, if the cart is in alignment on the first outer point but not the second, do I move it forward or backwards in the headshell?  Another thing alluding me...)  Could overhang be an issue?  The front of the cart extends somewhat beyond the end of the headshell, but I have no idea if that's right or not.  Would adjusting the VTA of the tonearm make a difference (it's at 0mm now)?


I did a little checking around and found that there are people who say that they've gotten the HFN test LP tracking bands to play perfectly with the AT 440MLa. Just wanted to make sure that you weren't on mission impossible.

The pattern of buzzing you are obtaining on side 2 suggests that you have run out of safety margins.

It appears to me that the cause of the buzzing is either not enough tracking force or excess azimuth error due to the method you're using to adjust overhang and offset angle.

You can hurt records more with mistracking than with moderate amounts of tracking force. Up to 2.5 grams won't damage records particularly if all you are doing is transcribing them by playing them a few times, which is what you should be doing.

cart set up, distortion

Reply #4 –
After another three and a half hours of messing with the alignment and the VTF the distortion on the tracking tests on side 2 is down to an absolute minimum, but I still can't get the cart to pass all the bias tests on side 1.  I don't have the right tools on hand to figure out the mounting distance beyond approximation (what the alignment generator requires), so I ended up using the linear offset method on the HFN protractor, and I think I got the alignment nailed in better than with the two point one.

Although at this point I'm getting really frustrated.  The vinyl sounds great in any case, so I'm tempted to just say the hell with it and just enjoy listening to it and moving it over to my PC.

cart set up, distortion

Reply #5 –
The +18db track on side 1 is, quite unhelpfully, already cut with major levels of distortion. It's physically impossible to play that track undistorted. As long as the cartridge doesn't skip, it's fine.
 

cart set up, distortion

Reply #6 –
Yes, I played that last band once or twice and gathered it would be ridiculous to try and pass it, so I focused only on the first 3 (12-16db).