Discussions on Cartridge Alignment

For Vinyl and Record lovers: turntables, cartridges, etc.

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Postby arnoldc » Mon May 21, 2007 8:10 am

dong, here's my opinion on this VTA/SRA issue-

1. SRA is more important than VTA
2. Your tonearm's VTA adjustment *may not* provide enough SRA variation
3. We'll never know the cutting angle used in each record during production
4. Records have different thickness which will slightly affect SRA/VTA
5. Records are not mafuctured the same way (I'm actually ranting on #3 and #4 above)
6. So I don't bother!

Last night, I decided to play with my ET-

1. I always configure it in a way where the arm tube is parallel to the record surface. The ET can be fitted with a buble level to ensure this is the case.
2. I measured the VTF, and confirmed it to be 2.00 grams which is what I wanted it to be.
3. I used the ET's on-the-fly VTA adjustment and tilted the arm tube downward at maximum (probably like more than half an inch up)
4. I measured the VTF and it shows, as expected, a change as it is now 2.10 grams.
5. I did the reverse and lowered the arm tube tail to the maximum
6. I measured the VTF and it shows 2.00 grams
7. I leveled the arm tube back
8. I measured the VTF and it shows 2.00 grams

What I conclude from this experiment-

1. That lifting your tone arm's arse will change the VTF, the opposite is not true.
2. How much change in SRA did the extreme position achieved? I have no idea as I don't have a proper tool to measure.
3. Did it made change to the music? In this combination, I will be fooling myself if I'd say I heard any change.


ps.

Is there a mathematician here? Can you figure out the delta from 90 degrees? The arm tube is 9". An estimate will do.

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Postby arnoldc » Mon May 21, 2007 8:31 am

I found this formula from the Roy Gandi, maker of Rega.

0.5/9 ≈ 0.055 ≈ sin(3°)

So, the 0.5" change I mentioned in my previous post will alter the VTA (not SRA) by 3°

But I'm faced with another mathematical problem- if the VTA was altered 3°, what will be the change in SRA?

This does not address my question still... :cry:

ps.

9 in the formula above means a 9" tonearm
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Postby zetroce » Mon May 21, 2007 8:41 am

arnoldc wrote:I found this formula from the Roy Gandi, maker of Rega.

0.5/9 ≈ 0.055 ≈ sin(3°)

So, the 0.5" change I mentioned in my previous post will alter the VTA (not SRA) by 3°

But I'm faced with another mathematical problem- if the VTA was altered 3°, what will be the change in SRA?

This does not address my question still... :cry:

ps.

9 in the formula above means a 9" tonearm


Will it not be the same? :?:
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Postby arnoldc » Mon May 21, 2007 8:48 am

No. And that is the most common misconception. That's why definition of the SRA and VTA must be clearly understood.

To be clear, check this out from The Analog Depot
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Postby zetroce » Mon May 21, 2007 10:27 am

arnoldc wrote:No. And that is the most common misconception. That's why definition of the SRA and VTA must be clearly understood.

To be clear, check this out from The Analog Depot


Hi Arnold,

The way i understand it is that SRA and VTA are using 2 different points of reference and will have different initial settings. But if we are talking about the angle difference ( delta ) if you may call it, in VTA and SRA as you adjust the armtube and tilt it downwards or upwards, the value should be the same, regardless if your reference is the vertical or horizontal plane.

Tama ba?
:?:
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Postby arnoldc » Mon May 21, 2007 10:37 am

No, I don't think so.
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Postby Hyperion » Mon May 21, 2007 1:11 pm

Assuming a perfectly stiff cantilever (like a diamond cantilever) and stylus, the relationship is pretty linear since the angle between the cantilever and the stylus (90° + VTA - if the stylus is perpendicular to the record) will always remain the same, i.e. increasing/decreasing the VTA will result into a similar corresponding degree of change in SRA. However reality is not so simple because of cantilever flex (and some of them arent even straight ... ) and usually because the stylus is much stiffer than the cantilever making the relationship non-linear. Still I think it would be safe to assume that the change in SRA will be quite close to the change in VTA.

For stylus perpendicular to record: SRA = 0. SRA = delta VTA.

For stylus less than perpendicular to record: negative SRA. SRA = negative initial SRA + delta VTA (subtraction)

For stylus more than perpendicular to record, SRA = positive initial SRA + delta VTA (addition)

In fact the relationship is exactly: New SRA = Initial SRA + delta VTA
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Postby BenC » Mon May 21, 2007 1:31 pm

Hi All,

Just for clarification, if the SRA per the borrowed diagram from t-n-t is more than 90 degrees, is this what we call NEGATIVE SRA? ... Less than 90 degrees, POSITIVE SRA? Thanks!

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Postby zetroce » Mon May 21, 2007 1:39 pm

Hyperion wrote:Assuming a perfectly stiff cantilever (like a diamond cantilever) and stylus, the relationship is pretty linear since the angle between the cantilever and the stylus (90° + VTA - if the stylus is perpendicular to the record) will always remain the same, i.e. increasing/decreasing the VTA will result into a similar corresponding degree of change in SRA. However reality is not so simple because of cantilever flex (and some of them arent even straight ... ) and usually because the stylus is much stiffer than the cantilever making the relationship non-linear. Still I think it would be safe to assume that the change in SRA will be quite close to the change in VTA.

For stylus perpendicular to record: SRA = 0. SRA = delta VTA.

For stylus less than perpendicular to record: negative SRA. SRA = negative initial SRA + delta VTA (subtraction)

For stylus more than perpendicular to record, SRA = positive initial SRA + delta VTA (addition)

In fact the relationship is exactly: New SRA = Initial SRA + delta VTA


That's how i understood it as well Hansen. The change in VTA ( angle ) is the same as that of the SRA ( angle ), in effect, considering setup environment, where the stylus and cantilever are not in motion and not tracking a record groove.
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Postby arnoldc » Mon May 21, 2007 1:54 pm

dong, see my definition of VTA. It's actually the movement on the vertical plane...
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Postby Hyperion » Mon May 21, 2007 2:15 pm

arnie,

well obviously VTA refers to something vertical otherwise it would have been known as HTA hehehe :D :D

Btw ...

1. That lifting your tone arm's arse will change the VTF, the opposite is not true.


This might be true with your ET but ... might not be true with heavier, higher mass pivoted arms with larger range of VTA adjustments.
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Postby arnoldc » Mon May 21, 2007 2:23 pm

hansen, di daw kasi agree si audiophileman sa definition ko (found in the previous page)

Yes, my experiment pertained specifically to the combination na ET 2.0 + clearaudio Aurum Alpha. The point being is that I'm not going to go crazy with this SRA/VTA thing since the cart is not sensitive to it anyway.

OT:

Di mo ba be benta yang 17D2 mo? Friendly price? :lol:
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Postby Hyperion » Mon May 21, 2007 2:44 pm

Cant sell it ... coz nag open yung right channel huhuhu ... :cry:
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Postby conspicuous » Mon May 21, 2007 3:03 pm

arnoldc wrote:conspicuous, the lateral frequency is the point where your cartridge get excited and vibrates from left to right. The vertical frequency is the point where you cartridge gets excited (literally) and it jumps up and down frantic fashion.


arnold, rod (audiophileman2002) - thank you for explaining this. thanks too for this discussion as i, and others i'm sure, am learning more about analog. so far it looks like trigonometry will suffice without having to go into differential equations yet :P :lol:

from the equations for lateral freq i can then deduce that the infamous "grado dance" is due to the relatively high compliance of the cantilever. or is it the other way around? if the cantilever is too stiff (low compliance) then it has a tendency to be excited to do the dance? (the grado dance describes the cartridge vibrating unwantedly from side to side at certain times) :?
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Postby audiophileman2002 » Mon May 21, 2007 7:41 pm

BenC wrote:Hi All,

Just for clarification, if the SRA per the borrowed diagram from t-n-t is more than 90 degrees, is this what we call NEGATIVE SRA? ... Less than 90 degrees, POSITIVE SRA? Thanks!

BenC


No, it is the other way around. If it is more than 90 deg. from perpendicular it is positive, less is negative. As I mentioned you'd want the top of the stylus more forward than the tip. This way the minute particles are blown off the groove. If the SRA is negative, the stylus rides over the minute particles and gets more imbedded, and you don't like this. You'd possibly like about a 2 deg. rake angle, therefore the stylus is 92 deg. from perpendicular.
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Postby audiophileman2002 » Mon May 21, 2007 7:52 pm

zetroce wrote:
arnoldc wrote:No. And that is the most common misconception. That's why definition of the SRA and VTA must be clearly understood.

To be clear, check this out from The Analog Depot


Hi Arnold,

The way i understand it is that SRA and VTA are using 2 different points of reference and will have different initial settings. But if we are talking about the angle difference ( delta ) if you may call it, in VTA and SRA as you adjust the armtube and tilt it downwards or upwards, the value should be the same, regardless if your reference is the vertical or horizontal plane.

Tama ba?
:?:


The angle between the 0 SRA and the cantilever for all practical purposes will be constant. For further explanations, pls. see comments below.
Last edited by audiophileman2002 on Tue May 22, 2007 1:58 am, edited 3 times in total.
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Postby audiophileman2002 » Mon May 21, 2007 8:08 pm

conspicuous wrote:
arnoldc wrote:conspicuous, the lateral frequency is the point where your cartridge get excited and vibrates from left to right. The vertical frequency is the point where you cartridge gets excited (literally) and it jumps up and down frantic fashion.


arnold, rod (audiophileman2002) - thank you for explaining this. thanks too for this discussion as i, and others i'm sure, am learning more about analog. so far it looks like trigonometry will suffice without having to go into differential equations yet :P :lol:

from the equations for lateral freq i can then deduce that the infamous "grado dance" is due to the relatively high compliance of the cantilever. or is it the other way around? if the cantilever is too stiff (low compliance) then it has a tendency to be excited to do the dance? (the grado dance describes the cartridge vibrating unwantedly from side to side at certain times) :?


I've done the resonance frequency calculation (tonearm/cartridge) for a good friend of mine for a Scoutmaster / JMW 9 / 501 II. Compliance of the 501 II is 9, weight of the cartridge is 8 g, the tonearm mass is 7.7 g. Theoretically, the resonance frequency is 13.19 Hz. I then phoned and spoke with HW and discussed this issue and he suggested for my friend to buy his 3 g headshell weight to lower the resonance. This weight costs $15 retail. I recalculated the resulting frequency is 12.1 Hz. This should be good enough.
It's you call if you want to purchase the VPI headshell weight of 3 g. Furthermore, it is also your call if you want to find out your actual resonance frequency. You have to purchase the HFNRR test record, $50 retail.
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Postby audiophileman2002 » Mon May 21, 2007 10:20 pm

I'd also like to make a point of clarification. The compliance of the cartridge is not just determined by the stiffness of the cantilever. The stiffness or softness whatever the situation is, is only a minor factor in the overall compliance of the cartridge. Major issue is the suspension at the back of the generator. The stiffness or softness of this suspension is the major factor in the determination of the compliance. The deterioration of the suspension, consequently the compliance is dependent on the material of the suspension. From how I understand the material is an elastomer which takes a very long time to deteriorate. I've had a very long discussion on this issue with Peter Lederman of Sound Smith. Part of the discussion was a re-tip & re-cantilever. Re-tipping and changing of the cantilever from aluminum to a ruby for instance, he claims will not do a major change in the compliance because of the explanation as stated above as the suspension remains the same. Of course the stiffer the cantilever the better and the material weight of the cantilever is also important. Aluminum cantilevers deteriorate over time due basically to the oxidation of the aluminum material. Choice of material is also difficult due to weight considerations. Why is weight important? Basically, the heavier the weight the less movement of the coil consequently sonic deterioration. Some commonly accepted cantilever materials are boron, diamond and ruby other than aluminum and various variations of aluminum alloys. There may be some others that I'm unaware of.
Furthermore, part of our long discussion went to the common stylus shapes. SRA sonically, is not so much an issue for spherical or conical stylus shape as this is just a point contact. It affects slightly elliptical shapes, more an issue with the Shibata, Ogura PA, VH Type I & II, super fineline, line contact & specially the enhanced line contact.
Again, for cartridges in which the manufacturer has closed there is no other option but to do a re-tip or re-tip / re-cantilever. For those with the manufacturers still existing one can do a cartridge exchange and therefore the suspension is always new and fresh.
Last edited by audiophileman2002 on Tue May 22, 2007 1:21 am, edited 2 times in total.
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Postby audiophileman2002 » Mon May 21, 2007 10:40 pm

Corollary to the above, the angle between the 0 SRA and the cantilever for all practical purposes will be constant. If there is ever a bending moment this is mostly affecting the pivot which is the suspension at the rear end of the generator because this material is softer than the cantilever. I'm not saying there will be no flex in the cantilever but this is so small that for all practical purposes the angle is about the same or constant. For the engineers, this would fall into mechanics and strength of material.
Therefore, in the actual sense wherein the cartridge parts are not deteriorated, the actual and theoretical is very much the same and therefore any change in VTA will correspond to almost the same equivalent change in the SRA.
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Postby audiophileman2002 » Mon May 21, 2007 11:17 pm

To give an idea how a MC cartridge looks like internally go to this link:
http://en.wikipedia.org/wiki/Image:Movi ... tridge.jpg

If you notice the entire generator assembly including what we call "cantilever" is by itself a cantilever in the sense the entire assembly is only held or secured / supported in one point, at the suspension. There is no other place where the assembly is being held or secured / supported on into position except at this point. The "cantilever" is secured by glue to the plate holding the coils and does not bend or flex at this point. The same with the connection between the plate holding the coils and the suspension. Therefore the entire assembly is technically a cantilever.
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