No need to. It is about the thickness of an LP, so leave it the same.
To date I have not adjusted VTA to compensate for the thickness of the mirror. Based on Doug Deacon's comments I'm going to measure things up and try with some VTA compensation. Anyway, based on my experience with the MintLp protractor so far I would say that you achieve great results even without doing so.
When using arc tractor, ideally the VTA should be set up exactly as you have it set up with your favorite record. Any discrepancy will add some level of distortion. This is illustrated in the link below.
The Mint's thicker than any LP I've seen, including old 230-240g Deccas. Alignment should be accomplished with all parameters as close to actual playing conditions as possible. Why align for any other condition?
This includes VTA, which your JMW provides an easy way to adjust. Why be lazy? Just crank the arm up until the cartidge is sitting at about the same angle as you normally play. Takes all of 2 seconds ...
In case anybody wonders how I got the offset number:
I modeled a hypothetical tonearm of 240mm in effective length.
I marked a point where the stylus meets the record with the VTA being horizontal to the record plane.
Another plane was added, which is 1mm higher than the original setup. This new plane represents a thicker record.
I then measured the vertical projection of the stylus sitting on the plane that is 1mm higher.
The overhand is now longer by 0.032485mm without VTA correction.
I don't know how relevant this number is in reference to distortion. This offset probably won't affect the sound much, but it will increase as the VTA increases or decreases from the original overhand setup using the arc protractor.
There is an excel file in this link at the bottom of the page. One can use it to verify distortion in reference to overhang.
I don't understand how changing VTA would alter/affect the Best Tractor's alignment.
Tvad, kindly bear with my somewhat leaden prose as I try to walk through it.
As an example, imagine changing SRA/VTA by moving the post of the tonearm up or down. Imagine the center of the arm's pivot fixed at the center of the post. (Some tonearms do not match this hypothetical.) Imagine the cartridge is correctly aligned to some known standard such as Baerwald.
Start with the stylus at a 90 degree angle to the horizontal plane of the record and the tonearm happens to be parallel to the record. Mentally put a stake in the exact spot where the stylus point sits.
Now, raise the arm on its post, which causes its pivot point to raise. The distance from the pivot to the stake has increased - the 'effective distance' (Pivot-to-Spindle + Overhang relative to stake) - has increased.
The length of the arm is fixed, so something has to give. The stylus point does not simply pivot at the point of the stake - it is moved/pulled rearward from the spot marked by the stake as the arm is raised. This changes its effective length relative to the presumably correct alignment marked by the stake, and thus changes alignment. Its not protractor specific.
The smaller the VTA change, the smaller the change to effective length, so whether a VTA change is worth a new alignment is up to your ears.
I think that's right.
True observation, Tvad. Overhang will surely change every time one plays an LP differing in height from the Mint (or whatever protractor was used).
Adjusting VTA/SRA is indeed an inexact science, but fortunately it's a very exact art. :-) We adjust by ear, for every record. Accurate sound is the goal. Accurate geometry is just a means to that end.
FWIW, most of our VTA adjustments are far less than the thickness of any mat, less than a sheet of paper even. I've posted it a zillion times and everyone thinks we're crazed - until they visit and hear the difference for themselves. Ask Dan_Ed or Swampwalker or Raul. They've all watched me raise or lower the arm by a hair's thickness and heard the sound snap into focus.
Whether its worth the effort is up to each of us of course, but for me it's become second nature and takes literally no playing time. We record the height for each LP so replay setups are instant.
Thom and others have suggested that Paul and I may become less particular about this after Mint-ing. That hasn't happened and isn't likely too. Why should improved stylus alignment in one plane encourage sloppiness in another? My lazy backside understands the appeal, but my ears don't.
Thom and others have suggested that Paul and I may become less particular about this after Mint-ing. That hasn't happened and isn't likely too. Why should improved stylus alignment in one plane encourage sloppiness in another? My lazy backside understands the appeal, but my ears don't.Errors tend to have a compounding effect.
Visualize how the front and rear of a line contact stylus contacts the groove when its offset angle is grossly skewed. Now raise and lower the VTA. You can almost "see" the rooster tail of vinyl being churned in the stylus' wake.
In contrast, compare how a perfectly tangent stylus being raised/lowered in the VTA plane "sees" the groove as the VTA is being changed.
Dunno, this makes intuitive sense to my powers of visualization. My first experience of an ET-2 (linear tracker) brought me to this line of thinking - after hearing how much less critical VTA settings were with this arm.
Ultimately as you say, it's VTA settings are an "exact art".
As I write the above, I'm thinking of along a tangential (sorry, I couldn't resist) line of thought about why perfect alignment matters.
Since we all have our trigonometry hats on, think about the force vectors on a misaligned stylus - how an intended 90 angle force to the cantilever is not a perfect 90 degrees - and how this can result in left/right distortion and a whole lot more (acceleration changes, and with it, changes to dynamic shadings).
Yet another way of saying to get your alignment right.
Thom @ Galibier
Good point about errors compounding, and interesting virtual observations from the stylus' POV. I've learned alot by doing those gedankenexperimenten.
The force vectors on a misaligned stylus must indeed put stresses on cantilever and suspension that no cartridge designer could plan for. Of course on a pivoting arm our zenith angle is *always* misaligned, except at two points. Therefore...
I've wistfully noted that the Mint helps me imagine what a good tangential tracker might sound like at all points across the LP. My dream has always been a Kuzma Air Line. Some day...
Mint-ing has greatly reduced distortion, but the increased clarity has also made the L to R shift in soundstage as the arm tracks between null points more audible than ever. "Watching" the musicians sidle slowly across the room and back is strange, who knew a string quartet could perform as a marching band?!
As you suggested, we did pay little attention to VTA during the first LP sides after Mint-ing. (Though we'd chosen familiar records, so the VTA # was known and dialed in out of habit.) The music is more holistic, as Swampwalker said, so it's easier to lose yourself in it and we do, very happily. But we're also both driven by an internal sense of what acoustic instruments sound like. Adjustments we know are needed will always be made. Pretty insufferable, I guess. :-)
Insufferable? Never! Your contributions to the corpus of collective knowledge is without peer. To really extract the most from analog, you have to be picky and anal-retentive...'close enough' will always lead the analog enthusiast astry.
I do hear what you mean about the 'slide-stepping' of the entire stage however - while I wouldn't say the Mint exaggerates this effect (which is simply part of any pivoted arm), the setup precision it affords allows this effect to be heard more clearly (along with everything else, good or bad).
I've been eyeing this linear tracker for several months now: http://www.trans-fi.com/. While I don't think it will humble my Triplanar, I do believe it will allow for some keen observations to be made: what will zero tracing error sound like - hell, I've never owned a linear tracking arm, so it'll all be new(s) to me. The price is right despite its rather rough-hewn look (it's no Air Line or Airtangent), but I think it could perform extremely well.
I'm curious if anyone has tried or heard one...maybe a separate thread on this. And yes, I did read the ETM review. Good listening,
Agree with Palsar, DD's (and Paul's) work in the vinyl domain is interesting and compelling-even if one doesn't follow his recommendations exactly as outlined, the knowledge gained can't help but influence your setup in a positive way.
You're missed over at VA Doug, but I'm grateful that I have access to your keen ear/experimentation here. Keep up the good work.
Amen, Doug, Richard ...
I frequently think about how better resolution allows you to hear more of the weird effects (sliding sound stage, etc.) as well as the good ones. The low distortion, low level detail resolution tells you a lot.
In the case of VTA, I think you hear less distortion when it's off, but you're likely more easily able to hear a shift in tonality. I'm a quite a bit more tolerant of slight tonal anomalies than I am of distortion - the latter driving me out of the room.
I think owning a linear tracker is at a minimum, a great learning experiment for inquisitive minds like yours (Richard, Doug). My experience came from the venerable ET-2.
With an unsuspeded turntable like your Teres (Doug), or your Galibier (Richard), you can easily fashion a big block of hardwood or aluminum to mount your linear tracker as a second arm, so it will be easy to compare against your existing Triplanars.
It's been some 4 years since I've done this, and it may be time to repeat the "experiment". The decision I made at the time was that the ET-2 did some amazing things, but lacked a bit of grunt.
I concluded that the ET-2 was as stunningly good as it was as much because it is brilliantly engineered, as it is because it is a linear tracker. Repeating a common theme I harp on, good design and execution show the pedigree of a product, and components with wildly different architectures (e.g. pivoting arms and linear trackers) converge because they are brilliant designs which are executed impeccably.
I'd love to sample the Kuzma. I'd also like to do a Triplanar - Linear Tracker taste test, now that I have a world class Triplanar alignment tool in my possession.
Interestingly, the alignment "protractor" you get (or can easily make) with your ET-2 is an "arc-protractor" of infinite length radius - a straight line. It would be interesting as well to try to replicate a slight alignment error with a linear tracker to see how it compares with the typical alignment we achieve with at two point protractor.
Are any of you aware of the Ladegaard, DIY linear tracker? Several of us in the original Teres build made them (I heard Jeremy Epstein's). It's a brilliant design that can be built on a kitchen table top. I kid you not.
I'm trying to remember who (I think it was Thomas Dunker) who forwarded us the files on the arm, but Roscoe Primrose posted them on his website:
Thom @ Galibier
Ah ... I took a look at the Trans-Fi tonearm. It's the Ladegaard design - leveraging the kitchen tabletop concept of using nested angled aluminum for the air bearing.
If this fellow has followed Ladegaard's general recommendations, then I'd say that this arm is most definitely worth a listen.
Thom @ Galibier
"I've wistfully noted that the Mint helps me imagine what a good tangenital tracker might sound like at all points across an LP.My dream has always been a Kuzma Airline.Some day."....
I hope you do realize "that" dream!....
Maybe you'll not think I'm as nuts as I've always come off,when you own such an "amazing instrument"!...Well,you'll have a definite different opinion of LP replay,at least -:)
I'm still "wistfully" imagining ANY kind of LP replay!
Thanks for the feedback.
The Mint tractor I ordered came in.
Originally I set up my cartridge using a Mobile Fidelity Geo-Disk.
The first thing I did, after receiving the Mint Tractor, was check the effective length and overhang, which was off by approximately 0.5mm according to the Tractor.
The line of sight on the Geo-disk is about 0.5mm thick so I must admit the Mint Tractor is a precision instrument.
Initially, the thought crossed my mind that maybe the Geo-disk set-up was close enough.
After thinking about it for a while, I decided to go ahead and adjust my cartridge to the Mint tractor.
The Mint Tractor is about the thickness of a 200gm record and I usually listen to 200 gm records about 22-26 clicks higher than at the setting I use for my thinnest records. So I initially adjusted the VTA to that setting using the VTA adjustment on the JMW 10.5i.
I then followed the instructions for positioning the cartridge and Mint Tractor for effective length and overhang, which took several iterations. When I was done I adjusted the Azimuth since it was slightly off. I checked he effective length and overhang to verify that it had not changed.
The Mint Tractor instructions suggest resting at this point and after an hour and a half the preliminary part of the set-up, I was too tired to continue. I waited until the next day to finish.
Afterwards, I listened to some old records that I bought used. They sounded unbelievably good. The Mint Tractor is nice upgrade to my system.