Aro Advice - Dynavector xx2 Mk2 optimisation.

[QUOTE]Originally posted by Mark Dunn:

I used the ARO's bubble level, centered on top of the bearing housing, to check this ......

/QUOTE]

Hi Mark,

I am not sure that ARO bubble level, centered on top of the bearing housing is best method. Did you check with cartridge spirit level? Here is my experience.

Best regards,
Lyubo

This is my "best sound" adjustment with cartridge spirit level, but ARO's bubble level, centered on top of the bearing housing is here ..

Hi Lyubomir,

I agree that it would be better to measure the 'levelness' at the headshell because you are then not relying on the headshell to arm tube, and arm tube to bearing cup conections being perfectly accurate. However, because the headshell is offset there is a practical difficulty in finding the point where the mass of the level itself, when resting on the headshell, is not affecting the amount of 'twist' of the arm.

Best Regards,
Mark Dunn

Mark thanks again for the advice to turn the main counterweight stub to allow proper azimuth centering and adjustment, it really works. I found after many measurements that turning the stub carefully has no affect on tracking weight and some people may find it more convenient to finely adjust arm twist than moving the azimuth weight itself.

Jeremy

What is 'finely adjusting arm twist'?

Mark - If the cartridgfe mass is borderline (between big and small counterweight) which one offers best performance in your experience?

quote:

Originally posted by Mark Dunn:


However, because the headshell is offset there is a practical difficulty in finding the point where the mass of the level itself, when resting on the headshell, is not affecting the amount of 'twist' of the arm.

Mark Dunn

Hi Mark,

The spirit level lies direct on the cartridge - not on the headshell. In this way I thing that headshell's offset doesn't matter. When I move the spirit level lightly to the left or to the right from center of the cartridge, this also have not an effect on the "leveling".

Best regards,
Lyubo

Lyubomir,

What happens if you put your cartridge spirit level on the cup? If it matches the circular level then your ARO wand must be out of alignment somehow.

Simon - what Mark has been talking about in recent posts.

Originally posted by John Dec'05

quote:

I am using a Ortofon SPU Royal N. Reading through other posts some members with this cartridge have the azimuth nut removed from the post entirely for this adjustment. I seem to be getting opposite results with the nut out as far as possible with blue tak (1/2 cm ball) added to the nut. This is so it will be lined up using the mirror method. This seems to have the effect of dampening the sound. When I remove weight the arm slopes down to the right but the sound is more open, highs and lows extended. I think the added weight is effecting the performance of the arm.

I had this same issue with my XX2, other member had the nut next to the cup, others with it removed with small amounts of blue tak. I required mine far out on the post. Is there something off with my ARO? Any ideas what to check? Is there a better method for adding weight to the nut?

Well at least there's one other person who's experienced the azimuth weight on the left hand side of the post!

Using the Aro spirit level, my stand, platter, armboard, plinth are all perfectly level, but even with the azimuth weight right on the left end of the post (away from cup), I could still do with a very small amount of weight to make the Aro cup perfectly level. I've tried adjusting the arm cables, but they have negligible effect.

quote:

Mark Dunn : "Firstly, the main counterweight's stub isn't uniform in its weight distribution. This is due the little knobbly thing that engages the thread inside the C/W. Thus, a gentle twist of the stub in the right direction may cure your problem

My Aro is 2 years old and my heavy counterweight is 6 months old, so unless things were different a few years ago, I can't honestly see why it's not machined uniformly. The knobbly thing is attached to the Aro arm and doesn't move if the counterweight is turned. If I turn the counterweight either way (even 180 degrees), the azimuth is not affected. Only the tracking force is changed.

A cartridge height of 18.7mm for the Kaitora, requires the arm to be raised to a position where the wire bias support is lower than the bias post. This requires me to bend the wire support into a new position so that the monofilament line is parallel to the deck.

Thanks for the interesting information Mark with regards to the angle at which the stylus contacts the groove walls. I used the Aro spirit level on the cup and slightly changed angles and there is a marked difference in the sound. I need to experiment more.

quote:

Originally posted by JeremyB:
Lyubomir,

What happens if you put your cartridge spirit level on the cup? If it matches the circular level then your ARO wand must be out of alignment somehow.

Hi Jeremy,

Here it is. When I move the spirit level on the bearing housing this have not an effect on the "leveling" - oposite on ARO's bubble level.

Best regards,
Lyubo

Hi Simon,

Re:

"Mark - If the cartridge mass is borderline (between big and small counterweight) which one offers best performance in your experience?"

I can't help with that one I'm afraid. My cartridge previous to the XV-1 was the first generation Te Kaitora which worked well with the normal counterweight. So, at that time I had no reason to purchase the heavy counterweight. However, with that said, from a mechanical viewpoint the heavy one would probably be better since getting the mass closer to the pivot point reduces the moment of inertia of the system. Perhaps if Dr. Peter is reading this thread he'll chime in with real life experience.


Lyubomir,

Re:

"The spirit level lies direct on the cartridge - not on the headshell. In this way I thing that headshell's offset doesn't matter. When I move the spirit level lightly to the left or to the right from center of the cartridge, this also have not an effect on the "leveling"."

Oh, I see. So the body of your VDH extends far enough forward of the headshell to allow the level to be placed upon it. Am I correct in this assumption?


count.d,

Re:

"My Aro is 2 years old and my heavy counterweight is 6 months old, so unless things were different a few years ago, I can't honestly see why it's not machined uniformly. The knobbly thing is attached to the Aro arm and doesn't move if the counterweight is turned. If I turn the counterweight either way (even 180 degrees), the azimuth is not affected. Only the tracking force is changed."

As long as the 'knobbly thing' on the main counterweight stub is at the 6 o'clock position (or 12 o'clock, I suppose) then it is, I assume, as the designer intended and the side mounted azimuth weight should be able to compensate for all cartridges whose mass falls within the ARO's stated parameters. However, if the stub is twisted even slightly, the change in position of the 'knobbly thing' causes the arm to tilt. Chris Koster at NANA suggested I check the position of my knobbly thing when I had some initial issues getting the XV-1 set correctly, and I was surprised how sensitive the ARO's bearing is to tiny changes in mass distribution.

So yes, I completely agree with you as long as the stub is correctly positioned and doesn't turn with the counterweight. Out of interest count.d, does your heavy counterweight have a left-hand thread? Mine does and I have no idea why, - save for the numpty on the lathe pushing the wrong button ;-)

Best Regards,
Mark Dunn

Hi Mark,
left hand numpty thread on both my heavy weights here.
Confirm knobbly thing position makes a big difference to bearing tilt over a narrow range of twist

Here's mine. Definitely not calibrated. Well it is now.

quote:

Originally posted by Simon Matthews:
If the cartridgfe mass is borderline (between big and small counterweight) which one offers best performance in your experience?

Here is an experiment to feel the extra weight of the heavy counterweight. Find an object similar to the naim level (flat, perfect circle), which weight gives approximately the difference between the heavy and the small counterweight. Place it precisely on the arm cup, so you keep the correct tracking weight, azimuth, etc. This could have some downsides but it will give you an idea of what the extra weight is causing to the sound.

quote:

Out of interest count.d, does your heavy counterweight have a left-hand thread? Mine does and I have no idea why, - save for the numpty on the lathe pushing the wrong button ;-)

Mark,

The heavy counterweight that I borrowed had the left thread, but the new one that was sent to me had a right-hand thread. Confusing?

quote:

5. Getting a unipivot arm set-up 'just so', so that it produces its best and with repeatable, consistent results is an annoying long term exercise, but nonetheless rewarding.

Since your post on Tuesday, I've tried adjusting the azimuth, using the bullseye method, for an even greater extraction of information and it was time well spent. I'm not sure if it's the Superline's revealing qualities or just your endless quest for perfection that has pushed me to find more from my Aro, but just when you think the Aro has peaked, it delivers more.

A basic sum up of what I've found and mostly learnt form you Mark:

The monofilament line must be perfectly parallel to the deck. Any deviation from parallel will cause a rotational force on the arm and kill the music. This will require bending of the wire hanger, using flat blade (non grip) pliers. The hanger's vertical wire must remain totally perpendicular to the deck and the small foot of the hanger must remain touching the arm board. If you fiddle enough, you can get the azimuth weight to just rest on the arm board, when the arm is parked, so that the arm doesn't rock all over the place when you're changing the lp.

The azimuth must be set using the bullseye level and a template on top of the Aro cup. The mirror reflection method is not accurate enough. This setting is so important with the Aro and is what releases it to sing.

I found VTA for Kaitora was best set at parallel for 200gr lp, then slightly lower for playing all others.

I've played around with adding extra mass to the azimuth weight coupled with moving onto the next closer notch, but have yet to come to a conclusion.

Most of the above has been said before, but I don't think it can be said enough.

I've followed your posts for almost eight years and would like to thank you for your efforts.

Hi count.d,

I'm glad it's working for you. I do envy you your Superline :-)

Best Reagrds,
Mark Dunn