Shelter and Triplanar matching ?

Dear Andre: I know that you are asking to Doug but after reading the thread answers it seems to me that if the arm board is exactly leveled ( flat ) and there is no internal tonearm antiskating problem then the problem is in the TP at different height ( Decca 200gr ) or the problem is that at this height is less sensible to that problem. Remember that the LPs are concave and at the begining is more thick than in the middle.

Now, you have to wait your new TP and " see " what happen . This is the first time that I heard that some one had a problem like this with a top cartridge/tonearm. It does not seems to me like a more noral tracking problem but more like a tonearm problem or unleveled one.

We can " think " many things about but the proof will be with your new TP.

Regards and enjoy the music.
Raul.

Dear Raul

The different test I am doing for three days are done with the RB 900 / shelter or DL 103 as the TP has been sended back and the problem with this tone arm ( RB 900) is still present.
.However I can confirm it was still worse with the TP but it is possible its my fault ( bad adjustment). So as soon as I receive the TP I ' ll set it up higher than last time and I 'll use exactly the CW as DOUG told me.Then I'll try to find the good adujstments for VTA and antiskating .
But today my feeling is that the lower the compliance is( as the AUDIOnote was) the most tolerant it will be faced to flaws of the records and vice versa.

In one sense I hope I am wrong...

André.

Raul,

Thank you! - for coming in and trying to help. Like you, I've rarely heard of this problem with good equipment. This is a tough one. No need to apologize. This isn't "my" thread. Everyone should try to help if they can.

The main tonearm problem I can imagine causing this is damaged, dirty or misadjusted bearings. For two tonearms to have that problem (or any one problem) seems unlikely.

The fact that it's audible with the RB900 but more audible with the TP may simply be due to the TP's greater transparency. (Just guessing, I don't know the RB900.)

I am leaning toward this idea: inadequate resistance to stylus drag. Large dynamics and warps both temporarily increase and then decrease drag resistance on the platter. If the platter slows and then quickly comes back up to speed, pitch changes on piano decays would be audible. A stretch and rebound cycle in the elastic drive belt that most PV's use might be involved.

Andre,

If the problem continues with the new/repaired TP, try adjusting or replacing your drive belt. If that helps "some" but not enough, here's the $500 solution...

The PV's I've seen all used elastic belts. The stretch in the belt is meant to absorb motor vibrations and cogging (assuming the motor is AC), but of course the belt may also stretch for a moment due to increased stylus drag from big dynamics or warps. I have tried several elastic belts on my Teres tables. None of them could maintain good speed stability.

I know that a few PV owners were dis-satisfied with this aspect of their rigs. When they tried a Teres motor and belt the problem was solved. The Teres motor is a very quiet, non-cogging (DC) type. There is no need for an elastic belt to isolate it from the platter, so it uses 1/2" (~1cm) wide mylar tape. This results in much better platter/motor coupling, so better dynamics and speed stability. I believe Galibier and Redpoint motors are similar in this respect.

Good luck and keep us posted,
Doug

Hi DOUG HI RAUL

I completly agree about the idea that the TP increases the problem because of its performance rather than because of any damage on it (we will see this next week).

Doug : thanks for the Teres motors idea ( I have soon sended an E- mail to have details).

What do you both think about the idea that the stiffer the cartridge is the most perfect the records must be ?

Thanks

André

Andre,

I think your idea has merit, and it's consistent with my theory.

If stylus drag is slowing the platter and causing your tremolo, anything which alters the amount of drag could alter the amount of tremolo.

We've established that the tremolo is worse after a large dynamic note or a warp. What is similar about these two events? Answer: both of them are trying to deflect the stylus. This requires some force. If the motor/belt aren't stable enough to overcome the resistance of the stylus/cantilever/suspension, the platter may slow.

(Bad tonearm bearings could increase the arm's resistance to rising freely over a warp. This would increase VTF and drag, which is why I thought of it. But since both your arms have the problem to some degree this seems unlikely.)

The amount of stylus drag will vary with cartridge and with setup. Here are some of the factors I can think of:

VTF - higher VTF = more friction (pretty obvious)

Compliance - the stiffer the cartridge suspension the more it resists deflection, greater resistance to deflection = more friction

Stylus profile
- fine line and micro-ridge styli cause the least friction
- elliptical styli cause more
- conical styli cause the most
This is simply a function of the contact area of each stylus type.

Anti-skate - the higher the AS setting, the more friction

Arm height
- arm tube level = normal VTF = normal friction
- arm down at stylus end = higher VTF = higher friction
- arm up at stylus end = lower VTF = lower friction
This ignores changes in VTA/SRA and any effects they may have on friction, but it might explain why you have less tremolo on 200g records than on thin ones. If you haven't raised the arm by the thickness of the record, VTF will be *slightly* reduced and therefore friction will be reduced. (I admit, this is really a stretch.) If those 200g records are less warped than the lighter ones, that would have a larger effect.

Doug