Alignment alternatives for pivoting arms

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Letitroll98

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Re: Alignment alternatives for pivoting arms
« Reply #20 on: 4 Jul 2010, 04:11 am »
Good to have you here, too, Letitroll :thumb:


John
Actually, I'm only here.  I'm permanently and forever banned over "there".  Send a PM here and I'll explain.
Harry over at VPI has always said the sweet spot in his tonearm choices are the 10 and 10.5" arms. 

I have both a table with 10" arm (JVC QL-Y66F) and 10.5" arm (VPI Classic) and the reduction of 'crunch' (tracking distortion) that I hear especially in piano pieces in noted next to 9" arms on other tables I own or have owned.

I haven't had a 12" to compare further.

Another nice thing about the longer arms as they naturally track better...you don't have to quite put in the gnats hair effort in dialing in their geometry.  In fact, I think the newest Well Tempered 10.5" arm has fixed mounts for cartridge...allowing no adjustment of overhang for various cartridges (as the differences are truly minimal because of the 10.5" arm length)
Do you know if he uses better quality bearings or any different materials in the longer arms?  Just from memory I believe the mounting plates are different, but the material for the arm wands and the bearings are the same, but I could be way wrong.  The VPI JMW series might be a good one to test out neo's theory about increased MOI being more detrimental that the offsetting benefit of reduced tracing error.  I should note that I have no position or preference here, just interested in the answer.
 

neobop

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Re: Alignment alternatives for pivoting arms
« Reply #21 on: 4 Jul 2010, 05:29 am »
Hey Mr Roll, how's it going? I was wondering why we hadn't heard from you in a while. Must have been your radical view, that not all cables sound the same, that got you busted at VE.  :icon_lol:

Aren't all the VPI arms unipivots?

I think you can get to the point where the downside of longer arms will outweigh the benefits, after a certain length. Think I agree with HW on this one, but it's a trade-off. I do notice a difference with arms with eff length greater than 240mm. Tracking angle error is reduced and I hear that. Some 12" arms can sound a little ponderous maybe. Trade off some immediacy for smoothness? VTA/SRA variations during a record are reduced with longer arms. Good bearings will improve performance but MOI is more a function of distance.

Good to hear from you Letitroll. This seems like as good a place as any to get into a nice argument, LOL. But be warned, DON'T SCARE OFF THE NEWBIES.

neo

Letitroll98

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Re: Alignment alternatives for pivoting arms
« Reply #22 on: 4 Jul 2010, 01:04 pm »
Yeah, what's funny is I had been on very good behavior for some time, but I didn't think PM's counted (one of which was the issue).  :?  As for newbies, ah what the hey, if my avatar and sig doesn't warn you enough it's your own lookout if you can't see reason.   8)

Anyway, back on topic.  Having been a plain vanilla Technics, then Thorens, then Project, then Rega vinyl guy, I never got into the esoteric longer length arms.  Even now the HW19 will only fit a 9" arm, but being in the VPI fold the possibility of 10.5" and 12" being included with upgraded tables looms in the future.  Thus my interest with no experience.

Yes, the JMW arms are all uni-pivots, varying mostly in mounting design.  So bearing improvements on that arm would be subtle in effect assuming even the lowest model to start out pretty good.  Harry might be upgrading the wand's materials or construction as you up in length, but I can't see any readily apparent differences.  Thus that series might be a good demonstration of your opinions on longer length arms, you could get apples to apples comparisons.  My original post was suggesting multiple bearing arm designers could improve the bearing design for tighter tolerances and less friction as well as altering materials and arm wand design to both lower the effect of higher MOI and lower the actual MOI respectively.  It's all more in the form of a question for those more experienced than I to reply to so that's why it kinda looks like spaghetti against the wall.  Your description of smoother but deader makes sense.         

neobop

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Re: Alignment alternatives for pivoting arms
« Reply #23 on: 14 Nov 2010, 08:02 pm »
Regarding Letitroll's comments directly above, about reducing negative effects on MOI with longer arms; I think that's a good point. More responsive bearings would improve MOI on any arm. It should also increase detail in  overall response, especially high frequencies. But there's no getting around the fact that the longer distance between stylus and arm bearing(s) necessitates a greater delay.

Also an interesting idea using VPI arms for comparative purposes. Unipivots don't have the same tolerance considerations as conventional pivots, and helps take that factor out of consideration. Although I guess the downside of greater length would increase with regular pivots.
neo

Wayner

Re: Alignment alternatives for pivoting arms
« Reply #24 on: 14 Nov 2010, 09:41 pm »
What the hell is MOI (hating acronyms)? At least hating ones that I don't know off hand.

Wayner

neobop

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Re: Alignment alternatives for pivoting arms
« Reply #25 on: 14 Nov 2010, 10:11 pm »
Moment of inertia

neo

neobop

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Re: Alignment alternatives for pivoting arms
« Reply #26 on: 30 Dec 2010, 02:31 pm »
I'm posting on this old thread because of the misconceptions about alignment exactitude and the implications. If you read the 1st few posts on page 1, you'll see that if your alignment is very close to whatever one you choose, it probably sounds fine and you're not damaging your records. If the angle/distance is such that your actual null points are within a mm or 2 of the target, then chances are (hopefully) you're in between different standard alignments.

The reason I bring this up is not to encourage sloppy alignment practices. It is so people contemplating getting into vinyl aren't intimidated and conclude that it's too much hassle and BS. I'm sure all this stuff, nulls, arcs, overhang, Loefgren & Baerwald etc, are a bit much if you're not familiar with them.

I highly recommend downloading a straight line protractor. This is nothing but a calibrated line, with no null grids. With it, and some magnification, you can see where your actual nulls are. If they are somewhere between 60mm and 120.9mm, then you're good to go. Maybe it can be improved, but you can still play a record without worrying about it. BTW, if you need magnification, try dollar store reading glasses. They take a little getting used to, but are very effective, and you have both hands free. Just take them off when you're not looking up close.

For those who understand the geometry; it's necessary to verify the alignment when changing overhang. This straight line protractor or an alignment specific protractor will provide verification. When changing overhang (going from 1 alignment to another), the angle changes as well.

neo

orthobiz

Re: Alignment alternatives for pivoting arms
« Reply #27 on: 30 Dec 2010, 03:35 pm »
Even now the HW19 will only fit a 9" arm

Had forgotten this thread, too. Not to hijack but is this statement true?

Paul

neobop

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Re: Alignment alternatives for pivoting arms
« Reply #28 on: 30 Dec 2010, 04:12 pm »
Had forgotten this thread, too. Not to hijack but is this statement true?

Paul

No, strictly speaking. I've seen arms longer than 9" on HW19s. Some people refer to 9 1/4" or 9 1/2" arms as 9", maybe that has something to do with the statement. I'd guess that a 10" VPI arm might fit within the limitations of the armboard. At some point you would run out of room or have the counterweight stub hanging over the end of the TT. Maybe a 12" arm would be too long. Back in the day, an MMT was a popular choice for the HW19. It's somewhat longer than 9". Any arm with eff length greater than 229mm, is longer than 9".

neo

orthobiz

Re: Alignment alternatives for pivoting arms
« Reply #29 on: 30 Dec 2010, 09:03 pm »
Thx neo
Paul

Wayner

Re: Alignment alternatives for pivoting arms
« Reply #30 on: 30 Dec 2010, 09:31 pm »
I have an HW19 and there is room to go in the corner. I'd say it might have 1 1/2" to go sideways before you got too close to the dust cover, and there is about an inch left from the stem of the c'weight assembly to the back of the dust cover. I'm currently running an Audioquest PT-6 and there is more then enough room. I might bet that the VPI 10.5" arm would fit. Not sure what it's spindle to pivot recommended distance is tho.

Wayner