Baffled by cartridge alignment!

[Infinitely Baffled]

Hello, All. I wonder if anyone out there can offer any wisdom on a matter that is puzzling me:

The arm on my turntable is a Fidelity Research FR 54. This model attaches to the armboard with a fixed-position pillar (ie. it does not have an SME-style sliding baseplate or anything like that). The headshell has slots in it to permit the setting of the correct stylus overhang. I am contemplating using a Fidelity Research integrated headshell/cartridge unit with it - the MC 702. As far as I can see from photographs, there is no means of adjusting stylus overhang or arm effective length with a cartridge like this. It must be the same with SPUs? How can the user then be assured of correct arm/stylus/platter geometry with no means of adjustment?

I'd be very interested to have your thoughts on this. Cheers. IB.

[337alant]

Yeah see what you mean
you would have to set the arm up as standard and if the cartridge does not line up propperly with the Null Points then I would adjust the pivot to spindle distance to suit, ou would need a slotted hole in the arm board for adjustment if it does not line up with the default values.
Not much infor on the carts as to which arms they are compattable with ?.

Ensure the Pivot to spindel distance is 230mm
Check Null points on a protractor at 59/120mm
Overhang 15mm

http://www.vinylengine.com/library/fidelity-research/fr-54.shtml

http://www.vinylengine.com/cartridge_database.php?m=Fidelity+Research&t=any&mod=&sort=2&Search=Search&sty=&ovlo=&ovhi=&can=&dclo=&dchi=&stid=&masslo=&masshi=&notes=&prlo=&prhi=

Alan

[Ammonite Audio]

If the tonearm has been placed at the correct distance from the centre of the platter (spindle-pivot distance), then the FR integrated headshell/cartridge will be correctly aligned to whatever geometry FR chose. This is all fine and dandy if the tonearm has been accurately placed and the cartridge cantilever is perfectly straight. These things cannot always be taken for granted, which is why I would prefer to have a headshell that offers fore/aft adjustment of the cartridge, as well as allowing the cartridge to be twisted. This allows you to set up the arm and cartridge to the best alignment geometry to suit the majority of your records; and that optimum geometry may not be what FR originally specified. It might well be, but it's nice to have options and there are no right or wrong answers here - just preferred compromises.

I do feel that a good alignment jig takes the mathematics and guesswork out of all this, and the Feickert NG is by far the best of the 'moderately priced' jigs offering Baerwald, Lofgren and Stevenson alignment which covers most bases. The Acoustical Systems SMARTractor is more clever and comprehensive and significantly makes aligning a cartridge by its cantilever very easy indeed; however it's not cheap. If you struggle with understanding alignment geometries, a well-designed alignment jig is possibly one of the best investments in vinyl, since the time taken to set up a cartridge properly is very much reduced, compared to other methods.

I did write up a piece on tonearm/cartridge alignment on my website here - https://ammonite-audio.co.uk/tonearm-and-cartridge-alignment/

[Barry]

When it comes to tonearm geometry Fidelity Research, like most Japanese manufacturers, tend to do their own thing. That is, the geometry they choose follows none of the recognised prescriptions (Baerwald, Loefgren or Stevenson) for minimum second harmonic tracking distortion.

That said, I would assume that the design of the integrated headshell FR-702 cartridge is such that when mounted in an FR arm, regardless of model, the geometry as chosen by FR is maintained. In fact you have no option, so don't worry.

This is the same situation one faces when using an integrated headshell cartridge with an arm from the same manufacturer, for example: Ortofon SPUG in an Ortofon arm; Sony XL55 in a Sony arm, or a Dynavector DV30B in a Dynavector arm etc.

Where there might be a problem is where an integrated headshell cartridge is used an arm made by a different manufacturer. A classic example is the use of an Ortofon SPUG in a Pioneer PL71 deck.

[Infinitely Baffled]

Thanks for these insights, fellows. It seems that my situation is quite straightforward really: all I can do is ensure the spindle-to-pivot distance is absolutely right, then just plug-in and play! Nothing else I can do - no faffing around with bendy card protractors, no azimuth adjustment. Just tracking force and arm height to see to and sit back to listen. In a way it's a bit of a shame. I read Hugh's short essay on cartridge alignment and got quite enthused about all the benefits that Dr Feickert could bring me. I suppose it appealed to the inner obsessive in me. I was just ready to reach for the plastic when it dawned on me that with absolutely nothing adjustable in this set-up, there was no point! It is what it is (as people love to say) and I had better just get on with enjoying it. Anyway, thanks to all for taking the trouble to respond - I am a good deal more reassured now. Cheers. Gary.

[Barry]

Gary, you will still need to check for the correct azimuth and adjust if necessary (use a mirror). That and the VTF, VTA and bias.

So just make sue the pivot to spindle distance is correct. if you have an old card alignment protractor mark points on it at 59mm and at 120.5mm to check tha tthe arm/cartridge geometry is correct. (You need only be accurate to within 0.5mm with the protractor markings, to be assured the overhang is correct to within 0.1mm).

[helma]

I think there was some sort of "standard", if not actual standard then at least de facto, for the stylus tip to mounting collar distance in Japanese tonearms. Can't remember what it was at the moment though. But taking into consideration how much Japanese MFGs had other people build things, sometimes even in cases where they made a similar product themselves, it would make sense there was some sort of agreement or established practice on this. To that end, for the most part I wouldn't worry when using a Japanese integrated cartridge/headshell unit in a Japanese tonearm, even when the MFGs were different. Never hurts to check the alignment of course.

Most japanese tonearms were designed with less than optimal alignment (IMO), but on the other hand I think the importance of alignment geometry is somewhat blown out of proportion. Like if you can hear significant differences in sound quality between say Löfgren A vs B, I'd say either you have really keen hearing and a very resolving system, or it's all in your head. In most cases I'd bet my money on the latter :) Like always I'll reserve the right to change my opinion on that any time, but that's what my current experience leads me to believe.

Vinylengine has excellent tonearm alignment plotter where you can enter the numbers and watch what happens to distortion and tracking angle error in the plots. I'd say the inner null point is more important to get right, once you have that set than I wouldn't worry about where exactly the outer nullpoint is, as long as you have one in a reasonable distance. Say, something like 60-70mm would be a good distance for the inner null point (I usually aim for 64-68mm) and then if you have an outer null point anywhere in the range of about 100-120mm you're good to go. Actually having the nullpoints a bit closer together than in most 'conventional' alignments makes real world sense to me, because it prioritizes the latter half of the disc where tracking is more demanding anyway and an added benefit is usually less offset angle which reduces skating force.

[Barry]

In general I would agree with you - ''close enough is good enough". But if you are going to the trouble of setting up the arm, you may as well as get it right. You might not be able to hear the diference between Baerwald or Loefgren, but the Baerwald presciption equalises the distortion at the start, the finish and at a mid-point along the record radius. Loefgren's prescription reduces the RMS distortion across the record but at the expense of increasing it significantly at the inner grooves; precisely what you should try to avoid.

I disagree with your last statement. Moving the two null-points closer together will reduce the distortion anywhere between them, but it will be increased outside them. Conversly moving the null-points apart will increase the tracking distortion between them and reduce the distortion outside them.

[petrat]

I use the Fidelity Research FR64s, and its alignment is, similarly, most odd. My turntable allows easy change of spindle-to-pivot distance, so can try different distances very easily. In order to 'force' it to align to Baerwald, it ends up being about 5mm further away than the manual suggests. Vinyl Engine's calculations say it should be 1.5mm further away than the manual recommendation. Now, I use an SPU, so that might throw things out a bit (as Kai says in post 7), but the bottom line is that they all work fine, and that alignment seems to have very little effect on this arm, compared to, say, adjusting the tracking force, or vertical tracking angle, or, even, bias.

[helma]

In general I would agree with you - ''close enough is good enough". But if you are going to the trouble of setting up the arm, you may as well as get it right. You might not be able to hear the diference between Baerwald or Loefgren, but the Baerwald presciption equalises the distortion at the start, the finish and at a mid-point along the record radius. Loefgren's prescription reduces the RMS distortion across the record but at the expense of increasing it significantly at the inner grooves; precisely what you should try to avoid.

I disagree with your last statement. Moving the two null-points closer together will reduce the distortion anywhere between them, but it will be increased outside them. Conversly moving the null-points apart will increase the tracking distortion between them and reduce the distortion outside them.

The point was to keep the inner null point near the Löfgren A / Baerwald null of 66mm - now if you move the outer null point from the 120mm to say 100mm, sure, it will increase distortion at the beginning of the disc, but it will reduce it between the null points AND after the inner null point. The further apart from each other the null points are, the steeper the rise in distortion once you get outside the null.

If by moving the null points closer together, you mean moving both the inner and outer null towards the center of the disc, then your statement is true and as an alignment I wouldn't recommend that, but if you keep the inner null point where it was and move the outer one closer to it, then certainly distortion outside the inner null point won't be increased, but decreased both sides of the null. The throwback will be increased tracking distortion at the beginning of disc.

To use a real world example, with the Fidelity Research FR-54 average RMS distortion using Baerwald will be 0.39% - the null points are roughly 66 and 120.
If you keep the inner null the same and move the outer one closer, to 101mm, average RMS distortion will be 0.47% - compared to Baerwald, all the penalty is taken at the outer grooves, but from around 112mm to the most inner groove, the new alignment performs better. Maximum distortion will be 1% at the outermost groove, compared to 0.6% in Baerwald alignment. Now the question becomes, is the very slightly higher average distortion and clearly higher distortion at the outer grooves worth the gains in performance from 112mm to the inside of the disc?

[Infinitely Baffled]

I use the Fidelity Research FR64s, and its alignment is, similarly, most odd .... In order to 'force' it to align to Baerwald, it ends up being about 5mm further away than the manual suggests.

Now you've got me worried! I suspect I must not be using/understanding the Vinyl Engine calculator correctly. Your FR64 tonearm has, I think, the same "manufacturer's" geometry as my 54. With a plug-in cartridge such as your SPU the only parameters you can vary are spindle-to-pivot and stylus overhang. And you can't adjust those independently of each other, since they each respond directly to a change in the other. So really the only adjustments you can make are to slide whole arm assembly either closer towards or further away from the spindle. I found by playing around with the VE calculator, that you couldn't vary that distance very much without the plot on the graph going nuts. If I moved mine 5mm further away from the spindle I would need to be playing a record the size of a car wheel to even register a single null-point according to the graph! What's your secret, Peter? Ah, I know; you've had the arm in a vise, haven't you, to do a sneaky adjustment to the offset angle?;)
IB

[DSJR]

It's my experience that the inner null point is by far the most important. Modern distance is around 60mm from disc centre, but older settings (which Rega still use) place this at 65mm and even 70mm on short-arm auto decks of yore. Tracking error goes mad in between this inner point and the matching outer one, which also varies. With an arm such as the FR, which I think is Rega length (I'm sure we used a Grace board back in the day which is also Rega effective length), I'd set it up at 60mm from record center and just enjoy some music from your records...

Nice pic below showing what happens with a Techie tonearm (SME length I think, which is about half an inch or so shorter than a Rega arm) -

http://i132.photobucket.com/albums/q8/DSJR_photos/06de1123.gif (http://s132.photobucket.com/user/DSJR_photos/media/06de1123.gif.html)

If you can't understand this, then just don't worry at all. All pivoted tonearms have tracking error built in, although 12" arms have less of this, but way increased effective mass.

[petrat]

Now you've got me worried! I suspect I must not be using/understanding the Vinyl Engine calculator correctly. Your FR64 tonearm has, I think, the same "manufacturer's" geometry as my 54. With a plug-in cartridge such as your SPU the only parameters you can vary are spindle-to-pivot and stylus overhang. And you can't adjust those independently of each other, since they each respond directly to a change in the other. So really the only adjustments you can make are to slide whole arm assembly either closer towards or further away from the spindle. I found by playing around with the VE calculator, that you couldn't vary that distance very much without the plot on the graph going nuts. If I moved mine 5mm further away from the spindle I would need to be playing a record the size of a car wheel to even register a single null-point according to the graph! What's your secret, Peter? Ah, I know; you've had the arm in a vise, haven't you, to do a sneaky adjustment to the offset angle?;)
IB

Well, I could be wrong. Explaining more precisely ... to exactly align with null points at 66 and 121mm, the pivot to spindle is at 234.5mm, with an SPU fitted. This isn't a calculated result, it comes from sliding the mounting until it aligns correctly, a trivial adjustment on my turntable which has a sliding fixture for the arm (same principle as SME). Why might this be wrong? Well, my alignment template is presumably designed for a 9 inch arm ... the FD64S is slightly longer. Or, the SPU length throws things off? OTOH, it works fine .... so, I don't worry too much.

[petrat]

Sorry ... double post for some reason ...

[SLS]

As an aside, I couldn't get my set-up correct using a Dr Feikert device. It made no sense. The arm mount was manufactured to the exact length required by the arm being mounted.

In despair, I called the manufacturer of the arm - a well-known UK company with a top reputation. Turns out they got their measurements wrong. Who you use the Dr Feikert you do get a good visual idea of how much alignment error is involved if it is not correct, especially if your cartridge has parallel sides.

I can't remember how I got it sorted, but I haven't touched it since. Sounds fine when I use my turntable, which now is fairly rarely.

[Infinitely Baffled]

I'd set it up at 60mm from record center and just enjoy some music from your records...


And from PETRAT:
OTOH, it works fine .... so, I don't worry too much.

I think these are the nuggets of wisdom to hang onto. Thanks, gentlemen.

As a matter of interest, the manufacturer plot on your picture, David, is very similar to what I get by putting the FR54 dimensions into the VE calculator and selecting "custom" - give or take. A bit of experimentation with different values appears to indicate that I could achieve a significantly better result by moving the arm pivot 1mm closer to the platter spindle and getting 1mm more overhang. However, given that my arm does not have an adjustable baseplate, the question becomes whether this theoretical improvement is worth re-working the armboard for. Almost certainly not, I suspect. Interesting, though, isn't it?
IB.

[Barry]

Well, I could be wrong. Explaining more precisely ... to exactly align with null points at 66 and 121mm, the pivot to spindle is at 234.5mm, with an SPU fitted. This isn't a calculated result, it comes from sliding the mounting until it aligns correctly, a trivial adjustment on my turntable which has a sliding fixture for the arm (same principle as SME). Why might this be wrong? Well, my alignment template is presumably designed for a 9 inch arm ... the FD64S is slightly longer. Or, the SPU length throws things off? OTOH, it works fine .... so, I don't worry too much.

The position of the null-points on the alignment protractor are independant of the arm used, and are determined by the radius of the innermost and outermost groove of the record, and of the optimisation scheme chosen for the arm geometry (i.e Baerwald, Loefgren or Stevenson etc.)

The fact that you can arrange matters so your SPU/FR64S has zero tracking error at the Baerwald null-pints of 66 and 121mm is precisely because you are able to alter the spigot-to-pivot distance using the sliding bedplate. This alters the overhang.

[petrat]

Thanks Barry!

A spigot, you say? Not seen a spigot since I last fell into the pub cellar :lol: