2. analog
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TT setup woes

I am having some difficulties in setting up a new (for me) analogue front end (Nottingham Hyperspace TT, OL Illustrious arm, Shelter 90X cart.). Intially I set the VTF to 1.9g; dialed in the overhang with DB protractor; and set the anti-skating bias at what the mft. of the arm said was a good starting point. The VTA looked and sounded a little off; but since the arm was as low as I could set it and it would be a week before I could get the collett machined so I could set the arm lower, I went ahead and tried it. It sounded wonderful. I listened to records all weekend. It tracked everything I played. Floated images out in space like I had never heard. Here's the problem. The next week I had another 0.100" machined off the outside of the collett. In my hurry to set the arm back up, I didn't notice that the wire cradle that holds the anti-skating bias bob weight had moved. The result was too much compensation. This was made apparent by the bad break-up, misstracking in the left channel on the inner tracks of one of my favorite albums. The anti-skating problem was corrected, but the buzzing on the albums played while it was off is still there. Records not played when there was a problem, seem to do OK. Also, the damaged (?) LPs seem to play OK on my old rig (MMF7, Clearaudio Vert. Wood). Both cart. have elliptical stylis. The sound now seems to be less satisfying. Female vocals have a slightly glazed or metalic sound to them and the imaging is not quite what I remember from my first sessions. How much of this is psychological due to my hearing it break-up; are the LPs in question damaged or is it still having problems with the TT setup; I don't know. Any help or suggetions will be appreciated. -JT
john_tracy
twl
3,251 posts
 
This is something that is very hard to diagnose for certain, without being there. I think that you are going to have to make the determination yourself, from your listening and adjusting process.

Even though damage to the record is unlikely, it could have happened. Playing ok with anouther rig and cartridge does not preclude possibility of damage, because the cartridge may trace a different area of the groove, depending on the stylus shape and dimensions, as Jameswei said.

I would also check the azimuth because the machining of the collet could have changed vertical alignment, and re-check all the cartridge alignments. The large VTA movement you did when you re-installed the machined collet could have affected the overhang adjustment slightly.

That sounds like a very nice rig, so it should be awesome sounding. Good luck.
dougdeacon
3,338 posts
 
Not much to add to what the others have said, except to suggest re-cleaning the affected LP's. Perhaps the excessive sidewall pressure ground some dirt into one sidewall. Certainly couldn't hurt to try.

Regarding VTA, I haven't heard the 90X but unlike Patrick we find our 901 to be VERY sensitive. Arm height changes of .04mm or so are clearly audible on the large majority of records. I am building a list and we're re-setting arm height with every change of label or record thickness. Boy that's fun :( Worth it when you find the magic spot though.
4yanx
1,576 posts
 
John, because I have some experience with the 'Not/Illustrious combination (you of all folks knowing why), I will probably mention some things that you have already done but that others might find useful. I would first suspect the azimuth as Tom has mentioned. Check the arm pod of the Hyperspace first to ensure that it is plumb and level with the platter plinth. Next, make sure that the collet ring is seated "plumb" such that the arm pillar is perpendicular to the platter. After these are successfully accomplished, check the azimuth (with a small spirit level on top of the headshell is possible). The Illustrious CAN be adjusted for azimuth by CAREFULLY loosening the hex nut located behind the headshell, CAREFULLY rotating the headshell, and the CAREFULLY re-tightening the nut. I am told that the re-tightening is most crucial so as not to collapse the arm tube.

The wire cradle for the anti-skate "bob" (according to OL) should be at approximately the angle as shown on the template provided. HOWEVER, there are many who believe that this cradle is best set to be perpendicular to the arm when the cartridge is positioned at the outer edge of a record. Too, the cradle is held with a tiny hex screw and it can get out of vertical - loosen the hex nut and make sure that the wire is fully seated in its "hole".

Here’s to hoping that you get back to your original sound. Oh, one last thing. Make sure that you tighten the two grub screws on the collar JUST tight enough to keep the arm from falling. Otherwise, if one is tightened more than the other it can throw of the pillar and put it out of “perpendicularity”! :-)
4yanx
1,576 posts
 
Hmmm, I have also heard others, in addition to Doug, comment that their 901 was sensitive to VTA. My 501 is far less picky about VTA than it is about VTF. Others have shared with me similar experience regarding the 501. No clue about the 90X, though.
john_tracy OP
341 posts
 
Thanks for all your help. Patrick, I did use HiFi News test record to reset the anti-skating bias. Tom, since the inside of the collett was fitted to a mandrel that was cut to fit on the lathe, the machining to the outside SHOULD be perp. to the pivot. Doug, I did reclean the records. I will say that when the problem first occured that the anti-skating bias was so out of whack that the arm would travel very rapidly to the outside of the record. I doubt if there was much force at all on the inside groove wall. I have noticed that small changes to the VTF do make a difference. After the tracking problem I set the VTF to 2.0g. I also rechecked the overhang with my protractor. I have since reset it to 1.85g. I have also noticed that amount of torgue (sp?) on the two set skrews for the pivot collett does affect the sound. Since machining the collett to allow the arm to sit lower does affect where the set skrews bite into the collett (and their leverage on it) I'm starting to wonder if this might be a factor also. Also, even with the 0.100" I had machined off, the cart. still appears to the eye to be slightly high in the ass. Should I have some more taken off? I guess I could blow all this headache off and go back to listening to those little silver M_F_ers.
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