VTA adjustment

gazza73

Active Member
Having just bought a pair of PMC OB1's I'm realising due to the revealing nature of these speakers that my turntable has either moved out of tune or I've never noticed how bad the sound was with my old Keilidhs.

So after a couple of nights of tinkering I think at the moment its sounding pretty hot. The only problem is the OB1's seem to change for the better every day during thier running in period so tunning the TT is a little difficult. So I want to get to a setup and stick to it untill the major changes the speakers are displaying start to slow down but without causing an damage to my presious vinyl.

If I set the downforce to within the recommended levels and then after listening alter the VTA does this alter the amount of downforce on the catridge due to raising the back of the arm up?

I'm finding at the moment my Gyro with Technoarm and Ortofon 540 like the VTA to be quite high. Does this sound farmiliar to anyone or am I miles off.
 

dynamic turtle

Active Member
Ooo, OB1's? Very nice speakers sir. Not everyone likes them but I certainly appreciate the power & directness of their communication. Very engaging....

AFAIK adjusting VTA doesn't affect downforce, but empirical observations with your weight guage (you MUST have one of these?!) might suggest otherwise.

The higher the VTA, the bassier the sound. Too low and it'll sound thin & scratchy. You have to account for record thickness and a host of other factors too, like cart warm-up times. All of these factors will affect the sound.

DT
 

karkus30

Banned
Having just bought a pair of PMC OB1's I'm realising due to the revealing nature of these speakers that my turntable has either moved out of tune or I've never noticed how bad the sound was with my old Keilidhs.

So after a couple of nights of tinkering I think at the moment its sounding pretty hot. The only problem is the OB1's seem to change for the better every day during thier running in period so tunning the TT is a little difficult. So I want to get to a setup and stick to it untill the major changes the speakers are displaying start to slow down but without causing an damage to my presious vinyl.

If I set the downforce to within the recommended levels and then after listening alter the VTA does this alter the amount of downforce on the catridge due to raising the back of the arm up?

I'm finding at the moment my Gyro with Technoarm and Ortofon 540 like the VTA to be quite high. Does this sound farmiliar to anyone or am I miles off.

Adjusting within the recommended specs is not all there is to it. The cart must track correctly first after setting up the VTA until the arm is parallel to the surface of an old record (saves scratching it). Make sure the cart is properly aligned and is not twisted in the headshell (a mirror an protractor are needed). Get a decent hifi test record and see how it tracks at the light end of the adjustment range, then increase if you get any signs of mistracking. VTA is the last thing to start adjusting. Most people have the VTA slightly low to enhance the bass (just a nats of parallel mind) and remember that by altering the VTA you are effectively altering the length of the arm so make sure that everything still lines up with the protractor.
 

gazza73

Active Member
Thanks Karkus. There is much more to this than meats the eye. I will have to invest in a test record. I understand the protractor but what is the purpose of the mirror?
 

karkus30

Banned
Thanks Karkus. There is much more to this than meats the eye. I will have to invest in a test record. I understand the protractor but what is the purpose of the mirror?

Use it underneath the headshell to make sure the stylus is aligned. It makes it easy to spot the cart being canted over or twisted. You can also use it to check the arm is parallel to to the platter........I cant explain how to do this and it is dependent on the arm and deck, but it can help give a different perspective.

You might also consider a spirit level (not a builders type) to ensure that the platter is level. This is critical to good playing. I use a little bubble gauge that I bought from RS components (circular thing about the sixe of a 50 pence piece).

Make sure the arm cable is not hindered in any way and it should not be dragging on or touching anything such as the mounting surface.

You will need a stylus gauge (simple Shure cantilever style) to measure downforce.

Then there is counter force that needs a whole different chapter :D
 

overkill

Distinguished Member
Thanks Karkus. There is much more to this than meats the eye. I will have to invest in a test record. I understand the protractor but what is the purpose of the mirror?
Get the Hifi news one. It's got a great alignment protractor. Some of the test tones are also useful. The best use of the mirror, can be (note 'can') for setting azimuth. If the cartridge image is lined up with it's original this is a rough guide. However, there is also a test tone on the LP. For me the mirror didn't work. What it said was right was way off according to the test tone! :eek: Also beware of taking the test records tracking tests literally. They don't work on every cartridge.

I would agree with Karkus, that getting the platter level is crucial, but often overlooked.

The most important thing is to get the alignment right. Get that wrong and it's audibly obvious.

On the anti skate, as Karkus says, this is a dark art. On my tonearm, with the current cartridge, you have to set the anti-skate to max to stop any drift towards the centre. You aren't 'supposed' to need to. ;) But you do....... Just set it at roughly the same level as the VTF. Then use the hifinews record to test. You won't get all of them, or often even beyond the first two.

The shure scales is another good recommendation from Karkus.
 

gazza73

Active Member
When I set the arm/cartridge to balance just above the surface of a record and the anti-skate is set to zero, my arm wants to pull back to the arm rest. Is this what the anti-skate switch does or is it my TT is not properly level. Makes it very hard when setting downforce as per the Techno weight instructions to get cartridge to hover then each blip on the weight is 0.1g.
 

karkus30

Banned
When I set the arm/cartridge to balance just above the surface of a record and the anti-skate is set to zero, my arm wants to pull back to the arm rest. Is this what the anti-skate switch does or is it my TT is not properly level. Makes it very hard when setting downforce as per the Techno weight instructions to get cartridge to hover then each blip on the weight is 0.1g.

Thats why it is critical to make sure things are right in a set order.

platter level, arm free from restriction (watch tight bearings and wiring) and parallel with surface or slightly negative, cartridge aligned with protractor and square in the headshell, correct downforce applied using a balance (not the arm weights as they are totally inaccurate, test with test record and make any alterations.

When you lift the arm onto its rest, it will quite often swing towards the outside of the platter its not a sign that anything is wrong. The test record will identify the anti skate setting, its difficult to sort it out any other way.
 

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