An easier way to set VTF/VTA/SRA? Perhaps....


I've occasionally advocated the need (over at Vinyl Asylum) for an additional alignment parameter in order to more easily find the desired tracking force (VTF) and stylus rake angle (SRA) interaction and easily adjust for changes in suspension elasticity. I refer to it as Weighted Cantilever Angle (WCA) which is the angle of the cantilever (from horizontal) where the manufacturer intended the cantilever to be positioned within the cartridge generator. (This would of course require manufacturers to provided the intended WCA for each cartridge.)

To align for WCA, a small angle gauge would be placed on the record surface to determine the cantilever angle as tracking force and tone arm height are adjusted to keep the headshell/cartridge body level. When the combination is found whereby the cartridge body is level and VTF and VTA/SRA provide the recommended WCA, then the optimal vertical cartridge alignment should be very close and only need fine-tuning.

The weighted cantilever angle could be easily checked periodically to see if there have been changes in the suspension.

Do you think this idea has merit? If not, what are the flaws in my thinking?

Tom
tketcham
Dertonarm, I never question the reports of others' personal experience(s) except in those (extremely rare) instances when I've had the same experiences only with quite different outcomes ;-)

I also think people need to be careful when assuming certain cause-effect relationships; and that they are responsible for the things they observe.

Because you observe that some cartridges you've worked with perform to spec right out of the box, doesn't disprove my assertion that there is a change, over time, in the elastomers; which there most definitely is, even in modern suspension materials, and especially for the cartridges you mention.

Most new (or even old) MC cartridges, unless they're defective, will perform "within a very narrow window within specs", as you put it, at a variety of loads and VTF settings. So what? I can easily make a brand new cartridge sound 100 hours old by loading it too high and applying a bit more VTF which will increase frequency response at the top and bottom until the suspension limbers up. I choose not to do that however knowing I'm going to have to do it all over again in 100 hours ;-) And because I enjoy hearing a cartridge going through its changes.

None of the three cartridges you mention are typical MC cartridges. They ALL have extremely LOW compliance, even for a MC (5 as opposed to 30 for most MC cartridges) and they all have HIGH VTF specs (3.5 to 9 grams!, as opposed to 2 grams for most MC cartridges.) So it's unlikely you'd hear any performance difference between brand new and 100 hours old, with any of those cartridges. In addition, those three cartridges are very low output and IMO not up to current performance standards ;-)
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Nsgarch, while I agree with you regarding the vast majority of custom MCs and their behavior, let me briefly add, that the 3 MC mentioned by me are quite different in their mechanical parameters.
The Ortofon is indeed asking for 3.5 + grams VTF, but the EMT and FR-7 are around 2.2 and 2.6 respectively.
The EMT isn't all that low compliance and has a lifespan of less than 3 years in use.
The dynamic compliance of the FR-7 and SPU is around 7-9, but indeed mark the low bottom of the range.
These 3 cartridges do perform to specs right out of the box NOT because of certain extreme mechanical parameters, but because they were designed and made to do so - as they had to meet broadcast (read: professional) standards.

While I agree that the SPU and EMT may not be up to full modern day standards in terms of overall sonic balance, I (...well known by now...) still have to mention, that no today cartridge is up to the overall sonic performance of the more refined versions of the FR-7.

I have mounted, aligned and heard extensively EVERY top-flight cartridge of the past 3 decades - with every top tonearm you name and in high-priced and quite sophisticated set-ups.

Very low output brings back the topic of high class matching SUT.........
First things first...

Well, Neil, I have well over 200 hours now on the cartridge so it's settled in nicely. (Much better term, I agree.) It sounds quite good right now but I won't try your installation protocol until the new tone arm arrives.

And regarding the VTF/SRA interaction, I may go ahead and measure the cantilever angle (WCA) of the current VTF and SRA settings and then use it (WCA) when I first install the cartridge on the new tone arm to set VTF and SRA. I'll just play records for a while and get to know the sound. Then, after using your recommended cartridge alignment protocol and things are sounding about the best they'll be, I'll measure the cantilever angle and compare the before and after WCA settings. Just for kicks.

Thanks again to you and D. for the opportunity to learn a thing or two about cartridges and setup.

Tom
Tom, I always wondered exactly HOW people (who cared to ;-) actually measured cantilever angle. One dare not risk damage to the cartridge by trying to put an instrument of some kind near the delicate cantilever mechanism while the stylus is resting in a groove - yikes!!

I guess one could take a macro picture using a telephoto lens (to minimize parallax error) and then measure the angle from the photo. But it seems like a lot of effort just to obtain anecdotal (read: useless ;-) information.

Sounds like you'll be ready to go once your new TA arrives. Take all the time necessary for you to feel confident you've zeroed in on the best VTF setting, before going on to establish the vertical SRA point. Do not worry that later, dialing-in the VTF just a little better (like even as much as +/- 0.1 gm) is going to screw up your SRA setting. Why? Because it won't affect it up anywhere near the amount a slightly different record thickness or slightly different cutting angle (as favored by various lathe operators) will. I already stated that SRA can't be an absolute for those reasons -- so don't sweat it. Just get it in the 1.4 degree ballpark and then (hopefully) your new TA has 'on the fly' tonearm height adjustment so you can adjust the SRA slightly for each recording. One of our members, dougdeacon, does that all the time using his Triplanar arm. He even notes the correct arm setting on each record!
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There's on-the-fly arm height adjustment so it'll be set it and forget it once things are dialed in, just as I'm doing now. I understand the merits of adjusting for the various record thicknesses to keep SRA near optimum but I guess I'm not serious enough about this to make it a priority. Now if a tone arm manufacturer came up with a way to have preset arm heights available with the click of a handy dial, and still maintain the structural rigidity of the arm assembly, then I might be interested.

I'm going to try to measure cantilever angle just for shits and grins, and I'll be very careful so as not to end up just saying 'shit'. The idea of using a photograph to measure the angle is worthy since I'd have to fabricate some type of gauge otherwise. Digital images are a snap to take and process.

But I should probably just abandon the whole notion of using cantilever angle as an alignment parameter. Obviously it isn't something anyone is using and you've been kindly dissuading me of the idea from the start. '-)

Tom