Need help trouble shooting 3D arm

Re: Need help trouble shooting 3D arm

Postby JimmyL » Thu Dec 20, 2018 4:58 pm

I am not the most experienced in this (more of a newb) but have just gone through a very extensive setup regimen so have a few things working my way now. From the picture you sent, your Lemo wire has an aggressive twist that's easily seen. Not sure who had suggested it but removing the arm and allowing the wire to dangle free while mildly untwisting (I even used a hair dyer to add a slight bit of heat), relieved a lot of the tension. After doing so, I found that the amount of skate was predictable and reasonably constant across the record surface and I could dial in the correct AS. Not sure it will solve your issue but I would start with that as I'm very pleased with the results I achieved.
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Re: Need help trouble shooting 3D arm

Postby Golear » Thu Dec 20, 2018 5:19 pm

I said in an earlier post that I wished there was a way to measure anti-skate force. I forgot that I did come across this:

http://www.simplyblack.net/WVC/tools/skater.htm

So whatever method you use - twisted wire/mechanical anti-skate/combination of both - you can measure the anti-skate at different spots, and make sure it's not too much or too little.

Seems like a worthwhile purchase, given how much one spends on an arm and cartridge, and so we don't damage our LPs via mistracking.

My approach is:
1. Set VTF to max recommended level.
2. Have minimal twist on the wire. And dress it so that it's a nice curve, and without kinks.
3. Set up the mechanical anti-skate as indicated in the "Modified Mechanical Anti-Skate" thread. The only variable will then be the position of the O-rings on the lower arm.
4. Adjust the O-rings on the lower arm, according to SoundSmith's method.

If you still hear mistracking on all LPs, then my view is that there's something wrong with the cartridge or the stylus. There might be uneven wear on the stylus.
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Re: Need help trouble shooting 3D arm

Postby Mr_Putty » Fri Dec 21, 2018 12:33 am

Audiom3,
Your photo shows your mechanical antiskate is not aligned correctly with your arm. The A/S mount needs to rotate clockwise about 20 degrees, viewed from the top. (The A/S line should be parallel with plane of travel of the two arms with the rubber donouts as much as possible.) This needs to be checked when the arm is near the center of a record. It’s best seen from the rear of the TT as a sight line. You will need the supplied Allen wrench to make an adjustment.
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Re: Need help trouble shooting 3D arm

Postby Bill Stevenson » Fri Dec 21, 2018 11:43 am

Follow up report:

Well my problem has resolved itself, but I am not sure what was wrong or what fixed it. I took Brf's advice and switched cartridges because I figured that any anti-skate issue would also be resolved in setting up the new arrangement. Putting the 2M Mono SE on the 3D arm worked fine. Putting the 2M Black on the metal arm also worked fine. Switching them back also worked fine. ??????? I have no idea what changed to fix the problem. I have a theory that the arm lift, which is very close to the 3D arm, might have been close enough to interfere. But it is only a theory since there is no interference now. To say the least I am frustrated.

If I were to trade up from my Prime, what VPI turntable would make the most sense? My dealer has both a used, like new TNT and an HRX on hand right now, and of course anything new is possible. This might just be talk, but right at the moment I am not loving my Prime.
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Re: Need help trouble shooting 3D arm

Postby jonathanb » Fri Dec 21, 2018 1:15 pm

Better to buy a new cartridge than a new turntable.
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Re: Need help trouble shooting 3D arm

Postby audiom3 » Fri Dec 21, 2018 1:27 pm

Bill Stevenson wrote:Follow up report:

Well my problem has resolved itself, but I am not sure what was wrong or what fixed it. I took Brf's advice and switched cartridges because I figured that any anti-skate issue would also be resolved in setting up the new arrangement. Putting the 2M Mono SE on the 3D arm worked fine. Putting the 2M Black on the metal arm also worked fine. Switching them back also worked fine. ??????? I have no idea what changed to fix the problem. I have a theory that the arm lift, which is very close to the 3D arm, might have been close enough to interfere. But it is only a theory since there is no interference now. To say the least I am frustrated.

If I were to trade up from my Prime, what VPI turntable would make the most sense? My dealer has both a used, like new TNT and an HRX on hand right now, and of course anything new is possible. This might just be talk, but right at the moment I am not loving my Prime.

It sounds to me like the 2M Black stylus wasn't all the way back into the body. I have a Red and Bronze and it's easy to slide them on but leave a tiny gap. And this will obviously throw off overhand among other things.
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Re: Need help trouble shooting 3D arm

Postby audiom3 » Fri Dec 21, 2018 2:00 pm

Thanks for your guys' help on my issue as well. I read Golear's A/S Thread and took some of the advice he gave. I moved the fishing line all the way down to the base of the top pole and only used one donut to hold it in place (as opposed to two). It changed where the lower shaft was at in it's pivot when the stylus was nearer the deadwax. It's closer to horizontal so I believe this gives more A/S. If I rotate the device as others have mentioned, it will pull the A/S device 'over the crown' and it'll fall backwards and thus, disengage. So that just doesn't work. It was late last night when I was finally able to play with the TT so I only tried Led Zep III (orig US) and it distorted just as badly. Probably just damaged from prior use. I have the next four days off so I'll be experimenting a lot.
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Re: Need help trouble shooting 3D arm

Postby Golear » Fri Dec 21, 2018 3:21 pm

audiom3 wrote:If I rotate the device as others have mentioned, it will pull the A/S device 'over the crown' and it'll fall backwards and thus, disengage. So that just doesn't work.


It's good that you moved the thread so that it is flush with the anti-skate hub, and used one O-ring. There will be minimal change in the angle that the thread makes to the horizontal plane, as the arm moves across the LP. And it precludes the upper arm from complicating things.

I think the body of the anti-skate device does need to be rotated as Mr Putty indicated. If it is in danger of going "over", then the thread is too short. Even if it doesn't go over, there'll be very low force on the thread. You can look at the pictures in the thread. On my turntable, it all works fine when the lower arm is at the 6 o'clock position, when the stylus is at the start of the LP. This sets a small amount of anti-skate force at the start, and this gradually increases as the tonearm goes across the LP.

And I'd add O-rings or O-rings and brass washers to the lower arm and move it, until the anti-skate works according to the SoundSmith's method. The SoundSmith does also stress that there should be no twist in the tonearm wire. If there's a twist, you may need to add or remove mass on the lower arm. The big advantage of my method is that it has just two adjustments: the amount of mass on the lower arm, and the position of that mass on the lower arm.

It's also true that you can't just listen to one LP, as it may be damaged. Better to play a wide range of LPs and listen for mistracking, sibilance, etc.
Last edited by Golear on Fri Dec 21, 2018 8:59 pm, edited 1 time in total.
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Re: Need help trouble shooting 3D arm

Postby Gshepardbuster » Fri Dec 21, 2018 7:47 pm

I also have a stainless arm along with a 3D arm on my Classic Signature. Now that I think about your issue I had the same. The stainless and 3D arm have a slightly different path along the lift arm pad. I had to slightly adjust the lifting arm when swapping arms to accommodate whichever arm was used. Otherwise about mid record I was getting skips.
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Re: Need help trouble shooting 3D arm

Postby Bill Stevenson » Fri Dec 21, 2018 9:31 pm

In what way did you adjust the lift pad to compensate for the two arms? It is interesting that you experienced it on the Classic, which in my opinion is a hell of a lot better TT than the Prime. But it does seem to be related to the arms rather than the TT itself.
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