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What's level?

M

minorrevival

pfm Member
A question: I've just noticed that if I put a spirit level on the headshell (SME 312s) perpendicular to the tone arm tube the reading is different to when I swivel it horizontally slightly so that it's parallel to the cartridge screws. I assume that the latter is the place to measure - is that right?
 
Level is level. Sounds like you might have a faulty bubble there. Joking aside, is your level a round one or a straight one ? The bubble in a round one shouldn't deviate even if you rotate it. However, your headshell may be level in line with the tonearm but not necessarily at 90 degrees to the arm (azimuth).
 
From this I infer that your headshell isn't flat. It should be.

The bit that counts is where the cart is bolted on of course.
 
You can't trust bubbles

Spirit levels should be checked sometimes & turning the thing through 180 deg gives different results

Its a bit anal but I use a laser level to set the deck, arm & headshell checks
 
Have Fun said:
You can't trust bubbles

Spirit levels should be checked sometimes & turning the thing through 180 deg gives different results
Click to expand...

If that's the case, you have a faulty bubble ! Haha ! ;) No, you have a faulty spirit level, it should read the same in both directions.
 
Or, alternatively (and more likely than any of the above), your headshell azimuth is incorrect.
 
If the arm height isn't set so that the headshell is horizontal then you will get this effect. Or the azimuth is out (which is much the same thing).

Paul
 
This would also happen if there is any discrepancy in levelling between the arm-base and platter, which there is on many decks, i.e. even if you level the platter it doesn't necessarily imply the horizontal arm-bearings sit on precisely the same plane. Given that SME are arguably the best mechanical engineering company in the entire audio industry my suspicion would be that the issue lies in areas other than the arm. For this reason I tend to choose arms with adjustable azimuth as I'm picky like that, though by saying that I'd not get too upset / OCD about it as there is certainly no such thing as a perfectly flat record. Such an item simply does not exist IME, they all have some degree of imperfection.
 
Thanks for all the input.
I checked the spirit level by turning it 180 degrees and you're right, there is in fact a small difference, but not as much as by rotating it between perpendicular to the armtube and parallel to the cartridge screws. I'll go & set the armtube so that it's horizontal along its length, try again and then report back.
 
Again, thanks to everyone for their help.
Well I went back and checked the level of everything - stand, turntable base, platter and armboard - and found that the base was out of true enough to notice (my less than perfect DIY skills in building the stand I suspect - see picture attached). That remedied, the rest fell into place.
Another lesson learnt....

DSC_0403.jpg
 
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