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Old 18th February 2011, 02:13 PM   #9841
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Quote:
Originally Posted by Soundminded View Post
. The stress on the vinyl is the Force divided by the contact area. Too low and the stylus loses contact with the groove at high modulation only to come crashing down to damge it on impact. Too high and it exceeds the vinyl's elastic limit. Plastic deformation occurs and the record never sounds the same because its shape does not recover.
Exactly here we have the problem.

ONLY Spheric Tip have a constant contact area on cantilever based cartridges, because the pivot and cantilever form a circlelike movement, NOT a radial one.

But cutter cut radial, since the suspension is on top and works like a pendulum.

If you use elliptic shape, no matter which kind, the diameter of the ellipse changes his angle with the modulation, this is for vertical AND horizontal movement.

Thus the contact area changes with Modulation. More movement = lesser contact area.

Spherics also change the angle with the same phase error, but since they are round, the contact area stays pretty much the same.

This is the basic problem, believe or not.

Thats why Decca London made a cartdrige with a different kind of cantilever/suspension, which reduced teh effect and introduced other problems. Also the Myabi with ringcantilever, which tried to imitate the cutting stylus movement. Both have their flaws.
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Old 18th February 2011, 02:27 PM   #9842
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Quote:
Originally Posted by mrfeedback View Post
I had a collectors record that continued to sound clean and lively despite repeated playings on a V-15 unitil I let it get played on a friends MC tt.
After that one play it never sounded the same back on my V-15....became dulled a bit and the dynamics got lost.
I have always been dubious of high tracking force cartridges.
Old piezo groove busters used to run at high vertical forces similar to MC.
A high force MC changes the groove on the first play which then stays sounding the same....I still reckon MM's can play with minimal damge to the groove.

Eric.

Try changing the tracking force slightly just for the next time you play this record. That may move the point of contact and give you a bit of untouched groove surface. Also a wet cleaning may help.
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Old 18th February 2011, 02:28 PM   #9843
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Furthermore, the top resonance of MMs can easily be controlled with capacitors and resistors to make the FR response pretty flat. This is good.
Bute then they roll off. This is not so good.


MCs have a different suspension, requiring more damping , because the resonance is usually more expressive. You can measure, most have between 3 and 12 db plus at apx. 20 Khz.
This come from the ultrastiff cantilevers.

Using a selfdamping cantilever made from alutube kills this resonance and make the FR flat up to 40 Khz easy.

But it require therefor highmass arms to track correct.
With spheric tip we go apx. 2,5gramms tracking force and it works faboulus, since the contact area is not getting smaller with modulation.

Elliptic tips reduce the contact area easliy by factor 4 due movement, thus your 1 gr tracking force is now the equivalent of 4 gramms. Oops!
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Old 18th February 2011, 02:37 PM   #9844
brianco is offline brianco  Ireland
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Having used low mass MC cartridges since a SPU/GTE in the 1960s, my experience of record damage has been almost non-existent from the time in the late 1970s I changed to a very high quality very close tolerance PU arm. I am quite convinced that in most cases the problem comes from a poorly assembled PU arm rattling around in it's less than perfect bearings. We must remember that these low compliance MCs do produce an amazing amount of purely mechanical energy and therefore need the best of arms to behave properly.....The old arms such as the early Thorens still used by some are not suitable unless the bearings are replaced with the best modern equivalents and then correctly adjusted. The old Fidelity Research 64s and 66s arms were probably as good a match for such cartridges as was ever available. With high compliance MMs - and I also had the ADC 26 way a long time ago - the high compliance came into play before poor bearings had too much effect other than on the sonics. Used properly in an appropriate arm the better low compliance MCs have a magical quality in their reproduction of decent recordings on pressings in good condition. [I had an early Wheaton Triplanar which, despite its obvious design and build quality, the bearings adjustments were never stable with an Audionote (Japan) original Io MC. The bearings needed tightening after as few as ten record sides.
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Old 18th February 2011, 02:44 PM   #9845
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Quote:
Originally Posted by brianco View Post
Having used low mass MC cartridges since a SPU/GTE in the 1960s, my experience of record damage has been almost non-existent from the time in the late 1970s I changed to a very high quality very close tolerance PU arm. I am quite convinced that in most cases the problem comes from a poorly assembled PU arm rattling around in it's less than perfect bearings. We must remember that these low compliance MCs do produce an amazing amount of purely mechanical energy and therefore need the best of arms to behave properly.....The old arms such as the early Thorens still used by some are not suitable unless the bearings are replaced with the best modern equivalents and then correctly adjusted. The old Fidelity Research 64s and 66s arms were probably as good a match for such cartridges as was ever available. With high compliance MMs - and I also had the ADC 26 way a long time ago - the high compliance came into play before poor bearings had too much effect other than on the sonics. Used properly in an appropriate arm the better low compliance MCs have a magical quality in their reproduction of decent recordings on pressings in good condition. [I had an early Wheaton Triplanar which, despite its obvious design and build quality, the bearings adjustments were never stable with an Audionote (Japan) original Io MC. The bearings needed tightening after as few as ten record sides.
The original Orton SPU has a spheric tip!
Also the Denon DL 103 Original.

The FR 64 and & 66 works very well with low compliance MCs.
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Old 18th February 2011, 02:45 PM   #9846
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Quote:
Originally Posted by Soundminded View Post
The stress on the vinyl is the Force divided by the contact area.
Chapeau! You got it right this time. Just talking about "tracking force" is misleading. Elastic deformation limits are related to pressure, not force.
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Old 18th February 2011, 02:54 PM   #9847
brianco is offline brianco  Ireland
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Quote:
Originally Posted by Groove-T View Post
The original Orton SPU has a spheric tip!
Also the Denon DL 103 Original.

The FR 64 and & 66 works very well with low compliance MCs.
Yes I know that the original SPU hada spherical tip, but the /GTE had an elliptical tip. The Denon 103 is as you know still available with an elliptical tip and I have one on order for testing a new tonearm which I am having machined right now ( to be fitted to a highly modified Lenco from your Country - which is where my family originated. I would like to still own my old FR arms again!!

Good luck.
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Old 18th February 2011, 03:07 PM   #9848
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Quote:
Originally Posted by brianco View Post
Yes I know that the original SPU hada spherical tip, but the /GTE had an elliptical tip. The Denon 103 is as you know still available with an elliptical tip and I have one on order for testing a new tonearm which I am having machined right now ( to be fitted to a highly modified Lenco from your Country - which is where my family originated. I would like to still own my old FR arms again!!

Good luck.
If you go with the 103 and spheric tip, you should decouple it from the headshell.
Use 2 small copper bars ( cut from antenna cable) between headshell and cartridge. Do NOT tighten the srews hard. Lift the arm apx 3-6 mm.
The 103 is good damped and this way it will not sound dull, like many people
say.
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Old 18th February 2011, 03:25 PM   #9849
brianco is offline brianco  Ireland
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Quote:
Originally Posted by Groove-T View Post
If you go with the 103 and spheric tip, you should decouple it from the headshell.
Use 2 small copper bars ( cut from antenna cable) between headshell and cartridge. Do NOT tighten the srews hard. Lift the arm apx 3-6 mm.
The 103 is good damped and this way it will not sound dull, like many people
say.

Thank you. I intend using a 3mm purest fine grain carbon as a damper between headshell and cartridge. (I use 5mm with the Io cartridge.) But I will try your method and report back.

Last edited by brianco; 18th February 2011 at 03:28 PM.
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Old 18th February 2011, 03:28 PM   #9850
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Talk about tweaks and mods! '-) However, I have found Denons to also sound 'dull' also. I have had 103C, D, and S (I think), and the top of the line unit, made today. I loaned it to Jack Bybee, and have not gotten it back. Oh well, the Helikon SL will most probably sound better, anyway.
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