My Linn Sondek LP12 was fixed by Mark last Saturday.
It broke over 6 months ago when, frustrated by the loose arm holder, I tilted the table up on it's side without removing the heavy platter. That is a big no-no for an LP12. The springs got twisted in such a way as to make the suspension constantly jittery.
The proper repair for a jittery suspension requires having a level jig for adjusting the turntable. I tried but was unable to order a genuine Linn one last year from Symbiosis in UK (their computer acknowledged my order but I never got a follow up email). When I first talked to Mark about the issue last year, he said he could probably fix it without the jig. But on Saturday he brought his jig and gave my Linn an adjustment which seemed almost chiropractic. He worked the springs over and over to get much of the "squeak" out. And after that, he did a very precise level adjustment.
And it also helps that my stand is now pretty well leveled. I thought it was perfect after I adjusted it a few months ago, but I've gotten better at reading these things and I now see it's off by about 0.1-0.2 degree, but that's much better than it was last year.) The turntable platter shows the exact same 0.1-0.2 degrees as the stand, so it appears the turntable adjustment itself is "perfect."
When playing records now, the turntable is totally serene, as in riding on glass. I see now the spinning platter helps to stabilize it a lot.
However if the turntable is NOT spinning, and you press down on the platter and let go, there will be some jittery movements. So that test may be too difficult and it is confusing to interpret.
I've played many records now (including Blood On The Tracks and Fresh Aire II) and there has been no case where the audio sounded the least bit jittery. So it seems that problem has been solved.
Mark also tested the speed with his KAB test record and said it was right on. I myself adjusted that (using my KAB disc and other methods) a year ago, but slight changes in the suspension position might cause it to go out.
Mark also fixed the arm holder. And just like me, in order to do that he tilted the turntable up to do that. But unlike me, he took the platter off first. And he only tilted it about 45 degrees.
He noted a sound in the bass (playing first track side two of Blood on the Tracks) that he called thuddish or thumpish. I thought I noticed it too.* He suggested I could use Mapleshade triple point feet on the Linn, or a better stand.
I didn't tell him I had removed a 6.1 gram additional headshell mass that I had been using before. I removed it prior to the adjustment because I myself was unsure if it was doing more good than harm, and it was annoying how it always stuck to the underside of the dust cover. I can see now that this mass or something like it (perhaps a tad smaller) is very much needed. (See the measurements in the next post.)
(*To some degree it might also be a peculiarity of the percussion Dylan uses on that track. Also Mark did not stay long enough to sit in my listening position, where the bass is much better balanced. It's a peculiarity of my system geometry that the least bass is heard in the front central listening position and it gets too loud elsewhere in the room. As of my last bass adjustment in July, the bass is optimized for the listening position specifically, more than I had ever done before, meaning it gets much worse elsewhere. I need to dial down the bass when I'm showing movies to a group of people sitting in the back of the room, and even more than before. But these effects would simply have made the problem more obvious...there was a problem and Mark correctly noticed it though I'm not keen on his solutions and I like mine better.)
He didn't use a clamp, which isn't too bad on a Linn, but I'm not sure if he removed the center felt washer I use for clamping. I'm not sure if the record could have even played with the washer there and no clamp, though I seem to recall it WAS there after I removed the record--perhaps that's a false memory. I didn't think the sound was THAT bad anyway, in fact I was listening to how nicely stable and solid it sounded compared to what it had been like just after I messed up the suspension. But the bass didn't sound exactly right either, though I wasn't focusing on that until he mentioned it.
I really do want to redesign this headshell mass (it's a "squished roll" of hockey tape, and I want to make it a more stable "stack" of hockey tape, plus add hockey tape around the Dynavector D17 V3 cartridge itself which I think has a high frequency mechanical resonance that's not controlled well by the thin piece of carbon fiber that constitutes a headshell on the Ittok arm. Possibly if the cartridge were attached to the heavy metal headshell of a Dynavector or Fidelity Research arm this wouldn't happen).
But for the time being I reattached the existing flattened-roll-of-tape mass. (That had always been intended to be temporary, until I figured out how much mass was needed, but then I lost confidence in my ability to determine what mass was correct.)
With the added mass, I believed I heard the old cleaner bass I was familiar with. However I should also admit that before I reattached the mass, I tried listening to the another record (Fresh Aire II) and my feeling was that there was no bass problem at all (in fact, it sounded fabulous, and was far more involving than the CD version). So I think this "thuddish bass problem" is true but not really that big a deal, you might not notice it on everything including other records with bass, especially in the listening position.
And I feared that restoring the headshell mass might bring the jitters back. In fact it was a bit worrysome that when Mark came over and did his first "bounce test" on the suspension, he said it didn't seem too bad. This made me think of several alternative explanations:
1) Perhaps the jitteryness was caused by the added headshell mass, either as an arm destabilization, or because it offset the Linn suspension from normal leveled balance sufficienty--it is very sensitive. Perhaps I didn't notice this at first until one day it was obvious from other factors being at the threshold too.
Two days of follow up experiments have demonstrated that this hypothesis was not true. Reattaching the headshell mass has not caused any kind of jitteryness either in sound or measurements.
Also I placed quarters on top of the platter where the cartridge would be tracking to see how they upset the table leveling. They made no detectable difference until I reached 6 quarters, about 31g, and then they caused about 0.01 degrees of difference, in my best estimation. Meanwhile the stand and table are off by about 0.1-0.2 degrees in the opposite direction. If anything, more headshell mass would make the table MORE level. But it appears not to make a significant difference at all, despite the incredibly sensitive suspension.
2) Perhaps they were caused somewhat by the table not being level. Last year I fixed the table level and re-tested and the problem had not gone away. But I can't remember if I did a real listening test, or just a table bounce test, and I apparently don't know how to do the bounce test or its interpretation correctly.
3) Perhaps the springs reset themselves by not being used for 6 months, by slowly releasing stored potential energy.
Anyway, as of now, either with or without the headshell mass, I'm feeling like I have the best turntable sound I've ever had.
Measurements of the table level with my digital level show that depending on axis it varies from 0.00 degrees to 0.15 degrees (with 0.05 and 0.10 in between). I doubt I've ever got it this good before. I think this is a significant factor in the current "best ever" sound.
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