JMW-9 tonearm with Audio Technica AT33PTG/II compatibility

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby Votan » Mon Aug 12, 2019 1:52 pm

izgoblin wrote:Assuming you agree, what are the likely culprits here with my setup and how exactly do I find and fix them?

Also from your last photo it seams that your azimuth maybe is not correct because I can see due the mirror that your cart-headshell turns a bit clockwise. Try to fix it visually at least (it's better with the crosstalk equilibrium using a test record) and listen again, but checking always to readjust your VTF to the correct one.
Concerning a/s and also that an 9"" tonearm needs a lot more a/s than what is capable to give only the lemo wire, it's very strange that your cantilevers have been deformed towards the spindle!
Prime Signature/10"3DR/Finite Element(FE) platform/ADS/Lyra Titan/VPI Ring/WW Silver Eclipse 8 Phono Cable/Groove+ SRX MkII Phono Stage/Moon 740 Pre/Moon 820 PSU/ATC 100 Active Speakers/AQ Niagara IC/WW Silver Electra A/C,FE Ref Rack/RPG Room Treatm.
User avatar
Votan
Senior Member
 
Posts: 176
Joined: Sun Dec 02, 2018 4:59 pm
Location: Greece

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby izgoblin » Tue Aug 13, 2019 11:53 am

Hello Votan (and thank you to everyone else here).

Here is the picture you requested of the antiskate position at the lead-in groove. Remember I have to manually set the arm down at the moment, so I took this picture with the motor off. Let me know if that is not helpful. I am curious as to what you notice here however.

antiskate.jpg
antiskate.jpg (124.16 KiB) Viewed 873 times


I was unable to get better pictures of the cart in play unfortunately. Not a great camera and certainly not a great cameraman.

I honestly had no idea that VPI's headquarters is within driving distance of my home and that they do turntable setup there. My next step is go to them in a couple of weeks and point out some key items that I have learned with everyone's help here. I am hopeful that by making whoever I talk to understand my various problems, they'll be careful to send me home with the cart really dialed in and not just installed like my dealer apparently did. Yes, an in-home setup would be better, but I feel like this is the best next step for me to take. Even with all of the detailed help provided here, I can't imagine I can get this done as well as someone from VPI will. At least I shouldn't be able to do it as well, anyway. :D

Of course, they wish to show me my upgrade path while I'm there, so hopefully this visit indeed accomplishes what I intended.
izgoblin
Jr. Member
 
Posts: 18
Joined: Tue Aug 06, 2019 10:56 am

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby Mr_Putty » Tue Aug 13, 2019 1:26 pm

izgoblin,
An overhead photo of the most recent setup will confirm what I think is your problem. I can’t see the exact geometry from your photo, but, your a/s mechanism is mounted on the right side of the phono cable connection box. My Prime came with it mounted on the left side of the box. Your TT may be different, but I don’t think so. We can see the lower arm of the a/s mechanism is in front of the lemo connector. This leads me to believe that the vertical plane of the a/s when rotating is not perpendicular to the vertical plane of the tonearm. I think this is the root of your problem. If I am correct about the alignments, your a/s is putting a lot of static resistance on your stylus when the record groove tells the arm to move inward. This would be similar to using more a/s than called for. BRF (and others) should be able to confirm what I am thinking.
Mr_Putty
Senior Member
 
Posts: 335
Joined: Mon Oct 30, 2017 11:44 am

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby Brf » Tue Aug 13, 2019 1:51 pm

Mr_Putty wrote:izgoblin,
An overhead photo of the most recent setup will confirm what I think is your problem. I can’t see the exact geometry from your photo, but, your a/s mechanism is mounted on the right side of the phono cable connection box. My Prime came with it mounted on the left side of the box. Your TT may be different, but I don’t think so. We can see the lower arm of the a/s mechanism is in front of the lemo connector. This leads me to believe that the vertical plane of the a/s when rotating is not perpendicular to the vertical plane of the tonearm. I think this is the root of your problem. If I am correct about the alignments, your a/s is putting a lot of static resistance on your stylus when the record groove tells the arm to move inward. This would be similar to using more a/s than called for. BRF (and others) should be able to confirm what I am thinking.


For tables not employing vta on the fly, the A/S mechanism is mounted on the right side of the phono interface box.
User avatar
Brf
Site Admin
 
Posts: 4193
Joined: Tue Aug 26, 2014 9:23 am

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby Votan » Tue Aug 13, 2019 1:59 pm

Dear izgoblin,
1. The way you take your up to now photos (all of them) having your view point slightly from the right side, it is misleading, making us think that the cantilever is supposedly pointing towards the spindle, but if they could be completely centered, we may not have this issue. Especialy for your 1st and 2rd carts that you weren't using a/s device, normaly lemo wire is not even able to compensate for the skating force, let alone giving a / s in excess of the skating one (which would probably justify a permanent cantilever inclination towards the spindle).
2. As I have mentioned in my previous post, your azimuth looks (at least from the point of view that you took your photos), that needs a realignment because it seems to tilt a bit clockwise.
3. Your a/s device as it seems in the photo, is wrongly adjusted, but I am not sure that it is the only suspect for the problems you face in your 3rd cart. Namely:
3.1. The 2 donuts on the upper pole that lock fishing line, normaly it's better to be moved as close as possible to the hub, but if you leave them as it's now then your fishing line remains horizontal which is also a good thing. But your loading (number of donuts) in the lower pole is (more or less) O.K. Maybe for a 9" tonearm you could make them 4.
3.2. It is a common assumption that the skating force starts from low in the lead in groove and is constantly (but not linear) increasing as the needle sails towards the lead out groove. So you have to make your a / s force to have almost the same increasing course through going towards the spindle. In doing that the lower pole must be aprox at the 06:00' o'clock when the needle is in the lead in groove and aprox at the 07:30' when the needle is in the lead out groove (look below (*) why).
3.3. Unfortunately, however, the point where your lower pole is already (aprox 08:00' o'clock) when your tonearm is in the lead in groove, is the point at which your a / s force is much higher than skating force, but it begins to decrease as the needle is marching in.
3.4. So, somewhere in the middle grooves of a record, your a/s force should start to become smaller than the skating force with a steadily decreasing course, while the skating force is becoming larger and larger. I can't know if this mismatch of these two opposing forces (torques more right) is the unique cause of your problems, but it's definitely something that's not normal at all.
3.5. The reason this happens to you is because your fishing line is shorter than it should be, or because your a/s device was positioned (from your dealer) slightly further from your tonearm's D-ring. You must replace your existing fishing line with a new one a bit longer in order your lower pole to be at 06:00' o'clock when your needle is in the lead in groove.

(*): "Depending on the loading of VPI a/s device, (number of rubber O rings) a/s force starts increasing when its lower pole is on 06:00’ o’clock and tops somewhere between 08:00’ ~08:30’ (depending on the loading, the higher the loading, the higher the top) and then it goes degreasing. This top should be a bit earlier for 9’’ arms and a bit later for 12’’ arms.
So, if an a/s device is engaged such a way that its lower pole is in 06:00’ ’o’clock the moment that the arm tracks in the lead in grooves, you can give to the arm a continuously increasing a/s force up to approximately 07:45’ ~ 08:30’ o’clock (of the lower pole) depending on its loading (the more loading, the higher the top). If you do that, then because most LP records have the lead out grooves before lower pole reaches 07:30’ o’clock, you are in the increasing area of a/s all the time. 
If in the above toque created from the a/s mechanism, we add the inevitable a/s force from lemo wire, which is continuously increasing, then we can have even better results concerning the toping of the a/s torque."
For more info look at some relevant posts of mine:
viewtopic.php?f=12&t=10610&start=90
Prime Signature/10"3DR/Finite Element(FE) platform/ADS/Lyra Titan/VPI Ring/WW Silver Eclipse 8 Phono Cable/Groove+ SRX MkII Phono Stage/Moon 740 Pre/Moon 820 PSU/ATC 100 Active Speakers/AQ Niagara IC/WW Silver Electra A/C,FE Ref Rack/RPG Room Treatm.
User avatar
Votan
Senior Member
 
Posts: 176
Joined: Sun Dec 02, 2018 4:59 pm
Location: Greece

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby izgoblin » Tue Aug 13, 2019 3:41 pm

Thanks again, Votan for all of that detailed information.

I will get new pictures of the first 2 carts, and I completely understand your point about the pictures not being centered, but I promise you, you can see that the cantilever is not straight from almost any angle on those first two. So by all means, the current problems must be addressed, but I cannot discount that there was at least one other problem occurring before the anti-skate device was installed.
izgoblin
Jr. Member
 
Posts: 18
Joined: Tue Aug 06, 2019 10:56 am

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby Votan » Tue Aug 13, 2019 3:58 pm

If your azimuth has an easily visible cw tilt when needle is in the groove, then due to VTF eccentric loading of cantilever, it is possible for it to drift off an inclination towards spindle even if the platter is not spinning.
Make VTF too much higher than max recommended and you can have a permanent inclination of cantilever...
Prime Signature/10"3DR/Finite Element(FE) platform/ADS/Lyra Titan/VPI Ring/WW Silver Eclipse 8 Phono Cable/Groove+ SRX MkII Phono Stage/Moon 740 Pre/Moon 820 PSU/ATC 100 Active Speakers/AQ Niagara IC/WW Silver Electra A/C,FE Ref Rack/RPG Room Treatm.
User avatar
Votan
Senior Member
 
Posts: 176
Joined: Sun Dec 02, 2018 4:59 pm
Location: Greece

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby madrac » Tue Aug 13, 2019 6:36 pm

Brf wrote:For tables not employing vta on the fly, the A/S mechanism is mounted on the right side of the phono interface box.


Hi Brent,
I'm not sure if this is 100% true for all tables - my Classic 1 (no VTA on the fly when I purchased) had the A/S device on the left side. Unless, of course, it was installed wrong by dealer or factory.
madrac
Senior Member
 
Posts: 179
Joined: Sun Jan 03, 2016 9:36 am

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby Brf » Tue Aug 13, 2019 6:57 pm

madrac wrote:
Brf wrote:For tables not employing vta on the fly, the A/S mechanism is mounted on the right side of the phono interface box.


Hi Brent,
I'm not sure if this is 100% true for all tables - my Classic 1 (no VTA on the fly when I purchased) had the A/S device on the left side. Unless, of course, it was installed wrong by dealer or factory.


Sorry I should have been more precise. I was referring to the JMW 9 tonearm a/s location.
User avatar
Brf
Site Admin
 
Posts: 4193
Joined: Tue Aug 26, 2014 9:23 am

Re: JMW-9 tonearm with Audio Technica AT33PTG/II compatibili

Postby kurtster » Thu Aug 15, 2019 12:40 am

izgoblin wrote:
PTG2nd.jpg

2) Here is my second AT33PTG/II. The obvious dust/cat hair is certainly embarrassing, but we here too see the same permanent skewing of the cantilever.


I thought of this picture about an hour ago as I noticed the sound going to hell on a side 4 of a set that I was doing. An AT with barely 100 hours on it. I took the headshell off an lo and behold it looked pretty much the same as yours. Got out the trusty Ultra Duster and gave it a good air blasting. Then found what seemed to be a tiny vinyl shaving snagged on the tip. Brushed that off and put it back on and we are good to go. Been playing a lot of brand new vinyl lately, hmmm. I used to do this somewhat regularly and I guessed it slipped my attention. My bad.
kurtster
Member
 
Posts: 30
Joined: Sat Sep 01, 2018 8:46 pm
Location: Northeast Ohio

PreviousNext

Return to Support Forum

Who is online

Users browsing this forum: No registered users and 16 guests

x