AudioCircle

Industry Circles => Well Tempered Lab => Topic started by: G E on 8 Feb 2014, 08:47 pm

Title: A question for the group
Post by: G E on 8 Feb 2014, 08:47 pm
My golf ball is not centered in the cup.

How critical is this to getting maximum performance?  Seems like this would impact the cartridge angle.

It sounds really fine as it is, is there more to be had?
Title: Re: A question for the group
Post by: SteevA on 9 Feb 2014, 12:27 am
In theory centering the ball will give you ideal geometry but, since there is a small amount of play around the cartridge screws which allows for a º or two of rotation of the cartridge, in practice centering the ball may not actually give you perfect allignment.

Steve
Title: Re: A question for the group
Post by: threadkiller on 10 Feb 2014, 07:38 pm
That is incorrect. The ball should always be centered. Something is off otherwise.
Title: Re: A question for the group
Post by: rollo on 10 Feb 2014, 07:57 pm
   Golf ball ??? What ?


charles
Title: Re: A question for the group
Post by: rob400 on 10 Feb 2014, 09:12 pm
+1 in agreement with Charlie (threadkiller) as usual. My Versalex sounds at its best when the ball is centre of the cup and around 1/3rd of the ball covered by silicone. Also wise to set azimuth dead on with cartridge at centre of LP position and don't over tighten the fixings. Nice and snug is perfect.
Title: Re: A question for the group
Post by: threadkiller on 11 Feb 2014, 05:44 am
Ding ding ding!
Someone else got today's answer correct and moves to the next round...
Congrats!
Title: Re: A question for the group
Post by: SteevA on 11 Feb 2014, 10:44 am
That is incorrect. The ball should always be centered. Something is off otherwise.
Only if you have the cartridge lined up squarely with the mounting plate. If you dont, centering the ball may produce the wrong cartridge allignment.

Mind you, moving the golf ball may not be enough to fix the misalignment.

Steve
Title: Re: A question for the group
Post by: watercourse on 11 Feb 2014, 05:04 pm
My golf ball is not centered in the cup.

How critical is this to getting maximum performance?  Seems like this would impact the cartridge angle.

It sounds really fine as it is, is there more to be had?
GE, your instincts are correct re: centering ball. IME you center it when the arm is over the LP side. You may have to also move the pulley a bit to get the pivot point central to cup, depending. At least I had to with my used Simplex.

Ditto previous posts on alignment and azimuth, except to add that you set azimuth with cantilever, not cart body, and as SteevA suggests, sometimes the play in headshell comes in handy with certain carts that don't like the 19 degree alignment as much.

This, along with getting damping right, are the most important ways to set up the table to sound it's best. Next, I'd say a good isolated platform and an aftermarket mat.

The frustrating part might be the trial and error process that may be short or long, depending on your cart and patience. However, diligence does pay off and the table doesn't go out of whack once set up.

Title: Re: A question for the group
Post by: threadkiller on 11 Feb 2014, 05:31 pm
Watercourse, you are wrong about azimuth.
Cartridge body, not cantilever.
Title: Re: A question for the group
Post by: G E on 11 Feb 2014, 05:36 pm
GE, your instincts are correct re: centering ball. IME you center it when the arm is over the LP side. You may have to also move the pulley a bit to get the pivot point central to cup, depending. At least I had to with my used Simplex.

Ditto previous posts on alignment and azimuth, except to add that you set azimuth with cantilever, not cart body, and as SteevA suggests, sometimes the play in headshell comes in handy with certain carts that don't like the 19 degree alignment as much.

This, along with getting damping right, are the most important ways to set up the table to sound it's best. Next, I'd say a good isolated platform and an aftermarket mat.

The frustrating part might be the trial and error process that may be short or long, depending on your cart and patience. However, diligence does pay off and the table doesn't go out of whack once set up.

Thanks for all the tips!  Looks like I need to dig out one of the records I keep at the ends of my stacks for the alignment - one that I don't care about

If anyone has a 3D printer it would be nifty to create a jig that fits on top of the cup. A hole would be dead center and a very slightly larger than the diameter of the golf ball. Align the ball to the hole and you are good to go. It probably needs to be hinged to allow its removal. Otherwise one would have to raise the ball to remove it risking rotation of the post.

I already upgraded the mat. The foam mat had sparkle preventer in it so it was replaced with my home brew cork mat. What a difference and no it wasn't due to changed vta.

Will also be getting a linear power supply.

Greg
Title: Re: A question for the group
Post by: watercourse on 11 Feb 2014, 05:44 pm
Ah yes, a 3D printer would be excellent! For this and many other turntable-related uses!

I posted a thought experiment on the other active thread, which conceptually should work. I'm on vacation otherwise would be reducing to practice and reporting back.
Title: Re: A question for the group
Post by: G E on 12 Feb 2014, 02:15 am
Ah yes, a 3D printer would be excellent! For this and many other turntable-related uses!

I posted a thought experiment on the other active thread, which conceptually should work. I'm on vacation otherwise would be reducing to practice and reporting back.

How about that!  We had similar Tranes of thought.

Still thinking about this alignment jig. 3D printing is a potentially elegant solution, but I have no printer, nor design expressed as an algorithm nor digitized image of a prototype.

I wonder if any plastic juice cans in the frozen foods section of my friendly grocer have an inner diameter equal to the outer diameter of Amadeus' cup?  The. It is simple enough to find the center and use a compass to scribe a circle with a diameter of a hair more than 1.680 inches. ( the diameter of the modern golf ball). Which is carefully cut out with scalpel or something more precise

That would get us in the ball park!
Title: Re: A question for the group
Post by: watercourse on 12 Feb 2014, 02:32 am
Go for it and report back if possible.

I tend to use materials at hand, both because the templates or jigs I've made in the past have required a few design or measurement iterations. Cardboard typically is a good start, and may be all that is needed in the end.

Speaking of iterations, what you might think about is how to accommodate for different depths/circumferences relative to amount of damping and/or fluid used in the cup. Might be useful to have a few versions of the jig with different circumferences in other words.

If successful, scanning and offering the jig as PDF can hopefully assist others on this circle.

PS you must be a jazz fan, you subconsciously mentioned Trane...  :thumb:
Title: Re: A question for the group
Post by: SteevA on 12 Feb 2014, 10:11 pm
If you use a jig to align the golf ball in the centre of the cup wont that just push the ball to the desired location but ignore whether or not the suspension point above it is also centred.

If that is the case, as soon as you remove the jig the ball will just move back to hanging directly under the suspension point.

I think, if it is to work as desired, when the suspension point is in the correct location the ball should not be actually touching the jig.

Personally, I don’t see it achieving any more than a bit of eye-balling from an elevated position.

Steve
Title: Re: A question for the group
Post by: watercourse on 12 Feb 2014, 10:34 pm
No, we are on the same page. What I'm suggesting is to use the jig to assist in

1. Rotating the arm pillar to the correct location
2. Ensuring the pulley is in the correct location

While the ball sits in the fluid. You don't use the jig to "push" the ball into place. There is some space between the jig and golf ball, which you will use to help center the ball.

I would say the jig only needs to be close enough to the ball, and uniform enough to be able to either "eye it" better, or so that you can use a ruler or other measuring device to fine tune (if you want/need more precision).

What I'm imagining is that the jig can be a single arc, or two complementary half-arcs - which would approximate what GE's design is getting at. They would "close-in" on the golf ball, and sit on top, just less permanent as the materials are less durable.
Title: Re: A question for the group
Post by: watercourse on 12 Feb 2014, 10:55 pm
One thought for the future: I would be interested to find out for myself whether there is a single point where the ball is centered in the cup both when the arm is in the middle of the LP, and when the arm is in the rest. IME experience so far, there isn't.

The Simplex manual unfortunately does not make this clear, although all drawings show the arm in the rest when centering. I have found that this places the ball far from center when playing a record.

This is relevant because IME distortion characteristics, tracking ability, and azimuth drift changes depending on where you decide center will be. The first two parameters audibly different.
Title: Re: A question for the group
Post by: G E on 13 Feb 2014, 12:55 am
Good questions.

My vision of the jig is to use it to set the alignment of the golf ball to be as close to the center of the cup as possible. Once the alignment is complete, the jig is removed: it's job is complete until the next time one wants to tinker with alignment. That is why I think it needs to be hinged halves to make it easy to remove.

I would hope the ball is centered regardless of where the headshell is in its arc arcross the record.

I wonder if one of the building supply centers have some plastic/PVC plumbing parts that would suit our purpose?  I think I'll check it out this weekend!
Title: Re: A question for the group
Post by: scaleautoart on 13 Feb 2014, 05:46 am
GE, your instincts are correct re: centering ball. IME you center it when the arm is over the LP side. You may have to also move the pulley a bit to get the pivot point central to cup, depending. At least I had to with my used Simplex.


New Simplex owner here...I don't have this issue. It stays centered across the whole record. You may want to re-hang the ball and make sure the line is not crossed, etc.
Title: Re: A question for the group
Post by: watercourse on 13 Feb 2014, 05:50 am
Half twist, yes.

Centering issue - not that simple, got it used. Have gotten to a point where azimuth stays put, but not always centered. Did you get yours new?
Title: Re: A question for the group
Post by: scaleautoart on 13 Feb 2014, 05:58 am
Yes...new...but had to re hang the ball :duh: All is good.  Do you see lots of movement?
Title: Re: A question for the group
Post by: watercourse on 13 Feb 2014, 06:11 am
My thought is that the pulley distance (from end of hanger) on mine may have been moved, leading to centering issues.

Actually, no movement at all, what I mean is that "centered" when in armrest is not "centered" when playing music. So that's not the case for you?
Title: Re: A question for the group
Post by: watercourse on 13 Feb 2014, 06:21 am
Well, reading your post again it is clear this is not a problem you have. Will check when I'm back in town.
Title: Re: A question for the group
Post by: threadkiller on 13 Feb 2014, 04:30 pm
OP, the ball of any WTL should be in the center of the cup whether the arm be at rest, in the first groove, middle, or last. If yours isn't the pillar probably isn't in the correct position, or it's strung wrong.
Good luck.
Title: Re: A question for the group
Post by: scaleautoart on 13 Feb 2014, 04:52 pm
^^^^^^^what he said^^^^^^^

It's Simple
Title: Re: A question for the group
Post by: watercourse on 13 Feb 2014, 05:05 pm
Can you do us a favor then, and measure from the end of the horizontal post to the rubber grommet? This should be helpful for Simplex owners.

For Amadeus owners, those of you that have no centering problems can also do the same for Amadeus tables.

That should at least control one variable.

The other issue about the thread: when you say don't overlap the thread, are you talking about in the grommet? A little further description would be helpful.
Title: Re: A question for the group
Post by: watercourse on 13 Feb 2014, 10:34 pm
Watercourse, you are wrong about azimuth.
Cartridge body, not cantilever.

Just saw this. Actually, if your cantilever is not skewed, you'd be correct threadkiller.

If you have a skewed cantilever - and in some cases, a high enough compliance cart that the cantilever is not dead-on center when playing - you would not be getting azimuth correct if you rely on the sides of the body. This is based on experience.

So, while in cases where cantilevers and cart bodies are in perfect alignment, aligning to the cart body could be a good way to set azimuth, I say just align to the cantilever, which will always be the correct way to set azimuth. I'm not alone in this method, btw.
Title: Re: A question for the group
Post by: watercourse on 14 Feb 2014, 12:38 am
OK, so I'm back now, and have looked at my setup. The fact that others have a consistently centered ball means that it can be achieved. Currently, I have the ball centered when it is midway-ish on a side. This means that it is closer on the right hand side by 1mm to the side of the cup when in the arm rest.

A couple of things after RTFM again:

1. I originally thought that the grommet "trench" was much narrower than I recalled, but it's pretty wide compared to the nylon thread. This means that there is potential for a lot of adjustment within the trench at the time you are hanging the ball, which renders the grommet distance less critical than I imagined (while away from the table).
2. I found that the amount of adjustment of the nylon thread that this trench allows can make the golf ball off by +/- 1mm from center (when using the nylon thread tubes compared to the sides of the cup). IOW, not off by a great deal.
3. The manual says damping cup placement is not critical. I would agree. I'd say the pivot point, i.e. the central vertical axis of the golf ball, is the critical distance we are looking for. This may lead to problems using the cup to gauge where center is, i.e. if the cup's central point is not on the same vertical axis with the golf ball. In other words, your reference may be off.
4. I am asking Mike Pranka whether using S-P distance to set the pivot point would be a good way to ensure that the arm is set up properly.

In the meantime, I've set up the arm from scratch, including rehanging. I've futzed around with moving the grommet to the point where the ball is central regardless of where the arm is - I guess I should have moved the grommet before, but assumed it had not been moved from factory settings - duh. Now the ball is always 5mm from the cup on all sides.

Now for the listening tests and azimuth drift - will report back. Aligned the cart square with the headshell, which was checked to be 19 degrees.

EDIT: In case anyone wants to know, the grommet is 29.75mm from the end of the horizontal rod.
Title: Re: A question for the group
Post by: threadkiller on 14 Feb 2014, 12:46 am
As to azimuth alignment, I go by what Firebaugh and Pranka do.
As for the rest, I just put an ice pick thru my eyes so I won't read another forum...
Have fun ! :thumb:
Title: Re: A question for the group
Post by: watercourse on 14 Feb 2014, 12:52 am
threadkiller: good thing you don't need to read this thread, it's meant for people that don't have the set up correct. Nor can you read it now anyways with a big hole in your eye I suppose.

Initial impressions: the outer groove distortion is improved...
Title: Re: A question for the group
Post by: scaleautoart on 14 Feb 2014, 01:38 am


In the meantime, I've set up the arm from scratch, including rehanging. I've futzed around with moving the grommet to the point where the ball is central regardless of where the arm is - I guess I should have moved the grommet before, but assumed it had not been moved from factory settings - duh. Now the ball is always 5mm from the cup on all sides.



Yep...the grommet sets front to back and swinging the arm left to right. Glad you decided to go back and set it up again ;)
Title: Re: A question for the group
Post by: watercourse on 14 Feb 2014, 01:44 am
Well, this bit of reverse-engineering has helped me very much, even though there are some that may not agree. My Shelter likes this alignment better too.
Title: Re: A question for the group
Post by: G E on 27 Feb 2014, 11:48 pm
Some of the developments so far...

Regarding a jig for easily centering the golf ball.  I realized it would be just as effective to have 3 spacers 120 degrees apart on the diameter of the cup.  They would be easy to install and remove etc, like miniature clothespins, the old fashioned kind with a long slot, not the kind with the spring..  I found some pieces of nylon/vinyl that were once part of a Hunter Ceiling Fan blade balancing kit.  I thought I could cut to my purpose.  As they say, close but no cigar.  Working with close tolerances on small pieces with a vice and hand tools just wasn't accurate enough.  Again, a 3D printer would be just the ticket to fabricate these things.

Anyway, I ended up just eyeballing it and it looks pretty close.  Still experimenting with VTA, silicone damping etc.

BTW, fine VTA adjustments are challenging.  I used small pieces of yellow electricians tape on the deck and on the post, made alignment marks on each so I could return to square one if things got too bulloxed.  An idea I have is to go to the local hardware store and get a large nylon/vinyl bolt and nut.  This could be put under the post for adjusting VTA.  Turning the nut would allow minute adjustments while supporting the post.  One still needs to tighten the set screw at each step, otherwise the post is not perpendicular.

I am using a DIY cork mat that replaces the stock one.  Much livelier sound.  I use the stock mat as a dust cover for the platter.

Lastly, I ordered a 12 V DC linear, regulated power supply and its over voltage protection module for Amadeus.  At 3.4 amp current capacity it is overkill, but I can use it for other projects when not spinning records.  I plan to set it at 11.5 volts and dialing the overvoltage cutout at 12.5 or so.  I thought about a battery power supply for about 10 seconds. 

ge
Title: Re: A question for the group
Post by: watercourse on 28 Feb 2014, 05:24 pm
Hi GE,

After doing measurements and modeling various alignments and mounting distances (see my other thread for more details), I retract my previous comment about centering the ball in the cup. Based on the modeling outputs, this has less significant effects (good or bad) compared to getting the 19 degree offset angle correct.

FYI, I did plug in the mounting distance for the 10.5" arm for the Amadeus, and found that the distortion curves were the "ideal" curves that I was aiming for in experimenting with my Simplex alignment. It is not achievable with the Simplex, but it is with the Amadeus and other WTA arms of the same effective length. This stands to reason of course, as the Amadeus was the first of the new Firebaugh designs, and all designs following used this model.

Again, these are all numbers, and the proof is in the listening. I don't have an Amadeus, so can't provide any more specific help.

One last thought: If there are issues that seem insurmountable though you have the offset angle correct, and the ball reasonable centered in the cup (and assuming VTA, VTF, damping, and azimuth are all correctly adjusted), you might consider a mismatch or problem with the cartridge itself.