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Finally dove into the MC pool... WOW

StepheK said:
BTW this is on a Technics SL-B2 belt drive table
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Your SL-B2 has an effective tonearm mass of 12 g. The AT OC9XML is a very compliant cartridge, designed for current low mass arms that are in the - 6 - 9 g. hood.
You can lower your effective mass by installing a lightweight headshell that's around 5-7 g thus enabling the counterweight to be nearer to the arm fulcrum.
 
UncleAng said:
Your SL-B2 has an effective tonearm mass of 12 g. The AT OC9XML is a very compliant cartridge, designed for current low mass arms that are in the - 6 - 9 g. hood.
You can lower your effective mass by installing a lightweight headshell that's around 5-7 g thus enabling the counterweight to be nearer to the arm fulcrum.
Click to expand...

Thanks. I did order a lighter head shell than the one I am using, that should help.
 
StepheK said:
Thanks. I did order a lighter head shell than the one I am using, that should help.
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I'd suggest getting a test record with a resonance track. The resonance of a properly setup tonearm-cartridge should be around 8-12Hz. I like 8-10 Hz. Weight of cartridge, headshell, counterbalance, anything handing off the tonearm directly effects the resonance frequency.

I like the Tacet Test record. It has other nice tests, too.

https://store.acousticsounds.com/d/95088/Tacet-Vinyl_Check-180_Gram_Vinyl_Record
 
Mr Boochie said:
For sure. That is why sometimes, once dialed in, it's better to let a sleeping dog lie. Then keep changing headshells and cartridges. Very subtle adjustments can make a big difference. I feel that sometimes testing new cartridges make not be fair. As the care taken to correctly adjust ALL parameters made not be done, in comparison tests.

A slightly mis-aligned MC is not going to perform to the best level. So, it's not the cartridge's fault, but how it was setup. ;)
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At the very least removable head shells should have two pins, top and bottom, on the barrel to improve consistency. I've always found single-pin head shells have a little wiggle that impacts azimuth but it is much less with a two-pin designs. Also, it is important to write down the setup adjustments for each cart/head shell so the tonearm can be quickly and accurately adjusted. Hopefully the tonearm has a way to index each adjustment. Otherwise, as you note, just leave it alone and enjoy the music.
 
AvFan said:
At the very least removable head shells should have two pins, top and bottom, on the barrel to improve consistency. I've always found single-pin head shells have a little wiggle that impacts azimuth but it is much less with a two-pin designs. Also, it is important to write down the setup adjustments for each cart/head shell so the tonearm can be quickly and accurately adjusted. Hopefully the tonearm has a way to index each adjustment. Otherwise, as you note, just leave it alone and enjoy the music.
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Writing and taking photos helps with setups. So nice having good cameras on phones. :thumbsup:
 
Aerobat said:
Me too. There is a lot of esoteric talk in this thread that doesn't apply to your TT, but if it sounds good go with it. :music:
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Even better they had a Natalie Merchant vinyl I hadn't see before :) I'm pretty sure that will sound good.
 
UncleAng said:
Your SL-B2 has an effective tonearm mass of 12 g. The AT OC9XML is a very compliant cartridge, designed for current low mass arms that are in the - 6 - 9 g. hood.
You can lower your effective mass by installing a lightweight headshell that's around 5-7 g thus enabling the counterweight to be nearer to the arm fulcrum.
Click to expand...

Another question. A while ago I added some mass to the pivot side of the tonearm counterweight to move the counterweight closer to the pivot, as I read somewhere the weight being closer to the pivot is a good thing. Would this also lower the effective mass of the tonearm? I was reading somewhere it would do that as well.

weight.jpg
 
StepheK said:
Another question. A while ago I added some mass to the pivot side of the tonearm counterweight to move the counterweight closer to the pivot, as I read somewhere the weight being closer to the pivot is a good thing. Would this also lower the effective mass of the tonearm? I was reading somewhere it would do that as well.
Click to expand...

Even though it is closer to the pivot point you are still adding weight which your XLM does not like.
Are you able to dial in 2 g VTF with a lighter headshell and without the added weight?

Effective tonearm mass is a complex formula. That said, the mass at the tonearm extremes affect it most. So headshell weight and counterweight mass are the major factors. But as the counterweight gets closer to the fulcrum it lowers effective mass; hence my original suggestion for a lighter headshell.

In your current configuration you have a counterweight PLUS an added weight, this would make effective mass rise exponentially.

Now you know why tapes and CD's were such a big hit.
 
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StepheK said:
There is SO much conflicting information about all this..
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Read the article.... here's the excerpt which I think you're referring to

The fine tuning weights, when used closer to the pivot than the main counterweight, will lower the effective mass of the arm. When used beyond the main counterweight they will have a smaller effect, and will sometimes raise, but other times lower, the effective mass of the tonearm.

I don't agree with the above as I can't see any logic to it. You've added mass, period. In extreme circumstances where you have a heavy cart and headshell the above may apply, i.e. using the fine tuning weights in addition to the counterweight in an effort to shift mass nearer to the fulcrum.

But if you can use a low weight headshell with your XLM and are still be able to dial in 2 g VTF with only your counterweight,, I'll guarantee you that you'll have lower effective mass than what Basis Audio is suggesting.
 
UncleAng said:
I don't agree with the above as I can't see any logic to it. You've added mass, period.
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But you have lowered the moment of inertia, especially when you add the mass to the counterweight closer to the pivot. It the mass of the counterweight was an exponential part of the effective mass, there is no way this tonearm would have a 12g effective mass to start with.

https://www.reed.lt/5196/research/tonearm-moment-of-inertia/

Research shows that Iw can be reduced by increasing the mass of counterweight and pushing it towards the bearings.
 
StepheK said:
What I was reading said adding weight to the inboard of the counter weight lowers the effective mass/moment of inertia by moving the counter weight close to the pivot. You say it exponentially raises it. I do plan on removing a couple of grams from the headshell too.

There is SO much conflicting information about all this...

https://www.basisaudio.com/effective-mass
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If you spilt the original counter weight and could move a portion of it closer to the pivot point then it effectively lowers the EM, this has been called variable EM….one could weigh the original counterweight and make a 60/40 or 70/30 and accomplish the same…

VR
Andy
 
StepheK said:
Research shows that Iw can be reduced by increasing the mass of counterweight and pushing it towards the bearings
Click to expand...

But that can only be done by decreasing the headshell weight. A true life story is in order here (mine).

In the late 70's I bought a fancy new Marantz 6300 TT; beautiful table with an S shaped tonearm.... and also a 13.4 g aluminum headshell with 'Marantz' embossed on it. It had a heavy counterweight to offset the headshell.

I was using a highly compliant Shure V15 IV that tracked at 1 g and VTF was set at 1.5 g with brush damper engaged. Cartridge weighed 6.4 g.

Did it work? Well, no; on warped records I got severe distortion as the stylus appeared to be disengaging from the groove... moment of inertia.
Picked up an aftermarket 6 g headshell and with that the counterweight was almost bottomed out when tracking at 1.5 g; so it was right at the pivot with only 1/4 turn of travel left.

StepheK said:
But you have lowered the moment of inertia, especially when you add the mass to the counterweight closer to the pivot
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Correct.

StepheK said:
It the mass of the counterweight was an exponential part of the effective mass, there is no way this tonearm would have a 12g effective mass to start with.
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Not just the mass of the counterweight itself but rather the symmetry of cart weight, headshell weight & VTF as an enabler for the counterweight to be as close to the pivot as possible.
 
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UncleAng said:
But that can only be done by decreasing the headshell weight.
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But that is not what these two articles written by turntable manufacturers are saying. Of course you have a right to disagree with them :)

Like I said there is a lot of conflicting information on this. I could link a dozen other forum discussions where people say what I posted is true, and other places people disagree.

https://www.vinylengine.com/turntable_forum/viewtopic.php?t=102412

"And the advantage of the heavier counterweight would be an reduction in effective mass."

"In the manual for the SME Series III, which has a bunch of lead plates for the counterweight, SME suggests more plates, which will balance the arm closer to the pivot, for lowest effective mass, and fewer plates, which will need to be farther from the pivot, for greater effective mass."

This PDF is interesting and they agree (as do you and I) that lowering the mass of the head shell has more impact, but it also shows through math that doubling the mass of the counterweight and moving it closer to the pivot will reduce the effective mass, not increase it.

http://www.cartchunk.org/audiotopics/ToneArmMechanics.pdf
 
As an illustration—If there’s a 20g EM tonearm with a solid one piece counterweight, and let’s say that weight weighs 100g, adding another weight no matter location will not reduce EM.

With the same tonearm however, if you split that 100g weight up and can move a portion closer to the pivot point it will effectively lower the EM…

VR
Andy
 
I wonder how much of this testing is done with EE's actually listening to records and confirming results ? How many of these guys are half deaf ?
 
StepheK said:
But that is not what these two articles written by turntable manufacturers are saying. Of course you have a right to disagree with them :)
Like I said there is a lot of conflicting information on this. I could link a dozen other forum discussions where people say what I posted is true, and other places people disagree.
https://www.vinylengine.com/turntable_forum/viewtopic.php?t=102412
"And the advantage of the heavier counterweight would be an reduction in effective mass."
"In the manual for the SME Series III, which has a bunch of lead plates for the counterweight, SME suggests more plates, which will balance the arm closer to the pivot, for lowest effective mass, and fewer plates, which will need to be farther from the pivot, for greater effective mass."
This PDF is interesting and they agree (as do you and I) that lowering the mass of the head shell has more impact, but it also shows through math that doubling the mass of the counterweight and moving it closer to the pivot will reduce the effective mass, not increase it.
http://www.cartchunk.org/audiotopics/ToneArmMechanics.pdf
Click to expand...


So within a certain range of mass --- is lower effective mass better?

Thanks!
 
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