LP 12 - how level ?

I'm sure it has a lot to do with the spirit level. You could use several and I bet they would all be marginally different!

I use Stabila a combination of the 81s 25cm and 40cm. They are calibrated, precisely accurate and long term stable. Make sure all surfaces are perfectly clean and look after the spirit level's surface.     

With respect to the spirit level, if you can adjust the "bubble" it can be "calibrated" simply by drawing two horizontal lines on a wall when it says it's level (start both from the same point) - but for the second line turn the level round. You then split the difference between the two lines and that is your "true" level mark. Place the spirit level along the true mark and adjust bubble to suit.

If you can't adjust the bubble it sometimes helps when levelling a surface to just turn the level around and try and split the bubble difference, not as easy but is possible.

I use a Stabila too. I find it's best to do the final measure diagonally in both planes to ensure as best level as possible. Don't forget to check again after tightening the spike's lock nuts on the Audiotech.

count.d posted:

I use Stabila a combination of the 81s 25cm and 40cm. They are calibrated, precisely accurate and long term stable. Make sure all surfaces are perfectly clean and look after the spirit level's surface.     

thanks for the recommendations. I think the real problem with my spirit level is a lack of sensitivity. The deck's peformance is night-and-day after just a quarter turn of the Audiotech spikes. Ideally this would be visible on the spirit level as an easily discerned (say 1mm) displacement of the bubble. Thats' not the case. My local hardware shop has the 81s 25cm - but the longer one should be better. I've been using my spirit level for many years now, without obvious problems. I'm thinking that with a lot of the colourations removed from the deck in going from a Cirkus suchassis and Arkiv cartridge to a Keel and Dyna xx2, that it's just easier to hear when it's truly level or not.

They are a bit costly, but google the spirit levels from Vogel Germany. I have seen models with accuracy of 0.8 mm/m down to 0.02mm/m.

The 0.02mm/m version is maybe a bit extreme, but the other models may be worth checking out. I am seriously considering buying one of these my self .  

2mmy posted:

They are a bit costly, but google the spirit levels from Vogel Germany. I have seen models with accuracy of 0.8 mm/m down to 0.02mm/m.

The 0.02mm/m version is maybe a bit extreme, but the other models may be worth checking out. I am seriously considering buying one of these my self .  

 

I have just been to talk to my 'engineering consultant' (qualified machine-shop expert) and he has shown me just what I want - an engineer's level. It's very expensive but is good enough to measure the thickness of a piece of paper slipped under one end. Understandably it's not a piece of loan equipment.

The accuracy of the 81s (0.5mm/m) is easily enough for setting up the deck. It's the user who needs to be meticulous and thorough by doing many measurements at different positions. The 40cm is best for the rack shelves is it's the approximate length of them. A mix of the 25cm and 40cm is best for the deck. Bear in mind, the plinths are rarely perfectly flat along their lengths, so you'll need to do quite few measurements. Shelves are rarely perfectly flat too.

dektop100 posted:

I have just been to talk to my 'engineering consultant' (qualified machine-shop expert) and he has shown me just what I want - an engineer's level. It's very expensive but is good enough to measure the thickness of a piece of paper slipped under one end. Understandably it's not a piece of loan equipment.

Workshop measuring equipment is a bit hit and miss, not very accurate at all. What you need is an autocollimator, far more accurate an great fun to use.

And, if you want to go the whole hog, use an interferometer to gauge the flatness or unflatness of your platter, you know it makes sense.

And, just when you've got your plinth as level as it can possibly be, you put your new state of the art spirit level on the platter only to discover that it's slightly off, with the error then compounded by centrifugal force, etc.

Of course, both platter and plinth should be absolutely level after setup, but in 27 years of LP12 ownership and maybe 10 rebuilds, most of them by experts, I've never seen that. Taking that as a given, I’ve always wondered which of the two should be more level? I’ve always felt that the rotating platter does more harm when it’s not level, but I’ve recently been persuaded that the plinth is more critical.

I can’t say for certain that I’ve ever noticed an improvement just from levelling, but a careful rebuild of the Mana stack once or twice a year pays dividends.

Colm

SiHancox posted:

With respect to the spirit level, if you can adjust the "bubble" it can be "calibrated" simply by drawing two horizontal lines on a wall when it says it's level (start both from the same point) - but for the second line turn the level round. You then split the difference between the two lines and that is your "true" level mark. Place the spirit level along the true mark and adjust bubble to suit.

If you can't adjust the bubble it sometimes helps when levelling a surface to just turn the level around and try and split the bubble difference, not as easy but is possible.

Good advice. All of the levels I’ve used are off by a hair, and so I’ve long been in the habit of flipping them around and watching for the point where the error becomes symmetrical. I have one of those circular Mana levels, and it’s slightly off too, easily demonstrated by just rotating the platter while it’s in place. I suspect the silkscreened logo on one side is dragging it down!

This thread has reminded me that I’m overdue for investing in what my brother in law would call a **** off spirit level – high quality, and adjustable.

Colm

count.d posted:

The accuracy of the 81s (0.5mm/m) is easily enough for setting up the deck. It's the user who needs to be meticulous and thorough by doing many measurements at different positions. The 40cm is best for the rack shelves is it's the approximate length of them. A mix of the 25cm and 40cm is best for the deck. Bear in mind, the plinths are rarely perfectly flat along their lengths, so you'll need to do quite few measurements. Shelves are rarely perfectly flat too.

I've obtained an 81s 25cm - it certainly shows that the plinth cannot be entirely true. The deck, however,  is working very well in it's current state of alignment and for now I'm inclined to use my new spirit level to try to keep it that way.

Corry posted:

Good advice. All of the levels I’ve used are off by a hair, and so I’ve long been in the habit of flipping them around and watching for the point where the error becomes symmetrical. I have one of those circular Mana levels, and it’s slightly off too, easily demonstrated by just rotating the platter while it’s in place. I suspect the silkscreened logo on one side is dragging it down!

 

Colm

This would not necessarily show that the spirit level is off. The platter could never be totally 100% level as it spins, otherwise it would be jammed in the bearing. The platter assembly is not level as it spins anyway time.

Those small circular spirit levels could be extremely accurately made, but the small area they cover often makes them very inaccurate due to dust and uneven surface. The lathe turning lines on the LP12 platter are enough to throw these small levels out. 

dektop100 posted:

Last week the sound quality from my LP 12 feel apart. This wasn't the first time. From previous experience I knew this was likely to be due to something in the Audiotech wall shelf 'changing' . After removing the deck, careful inspection revealed less than perfect contact at one of the spike-to-platform interfaces. (...) I readjusted two spikes by just a quarter of a turn - hardly enough to move the bubble - and this then restored performance to the, normal, spectacular level. Just a quarter of a turn. Barely measurable.  

Any chance the issue was just seating of the board on the spikes than an actual issue with level? I doubt a hair off in level would make the deck sound off (given that platter level varies with the record you are playing given the eccentric nature of weight distribution on an LP12) but a less-than-close contact between spike and board could have been corrected by the small turn.

Something to ponder.

ricsimas posted:

dektop100 posted:

Last week the sound quality from my LP 12 feel apart. This wasn't the first time. From previous experience I knew this was likely to be due to something in the Audiotech wall shelf 'changing' . After removing the deck, careful inspection revealed less than perfect contact at one of the spike-to-platform interfaces. (...) I readjusted two spikes by just a quarter of a turn - hardly enough to move the bubble - and this then restored performance to the, normal, spectacular level. Just a quarter of a turn. Barely measurable.  

Any chance the issue was just seating of the board on the spikes than an actual issue with level? I doubt a hair off in level would make the deck sound off (given that platter level varies with the record you are playing given the eccentric nature of weight distribution on an LP12) but a less-than-close contact between spike and board could have been corrected by the small turn.

Something to ponder.

I was very careful to ensure good contact with the spikes all round (this was the initial problem that I detected and cured).  I've no idea if the deck is perfectly level or not and I purposely haven't tried measuring the platter - I think this may just add uncertainties. I've a feeling that levelling measurements may only go so far -  it's not clear that key parts in a LP 12 may be level wrt to each other at set up anyway. Then you can throw in the uncertainties introduced by a out-of-square plinth. Maybe an installation should just regard spirit levelling as a ball-park procedure - followed, if you have the patience, by fine-tuning the levelness with a set of small adjustments and listening tests.

The deck is not that sensitive to minute differences in level - if that was the case, differences in record weight would make a much bigger difference.

In terms of set up, starting with a plinth that is true (if out of square, it should be replaced), one levels the armboard with the plinth - this should ensure that platter and armboard are level.

However, once you put a record on the platter, this system deflects towards that direction (you can observe this by looking at the now slight difference in armboard vs. plinth cutout level).

Are you using a Trampolin by any chance?

One solution might be to get a new bubble. 

Regards,

Nick

dektop100 posted:

Last week the sound quality from my LP 12 feel apart. This wasn't the first time. From previous experience I knew this was likely to be due to something in the Audiotech wall shelf 'changing' .

dektop,

There is one thing that could be influencing the problem of levelling. I also have an Audiotech wall shelf, from the '80s, which is probably a similar vintage to yours. Over time the shelf board can warp and the slight sag could influence your results when trying to get things level. Aside from replacing the board, you can buy a replacement board from Tiger Paw, is to use Fraim glass and balls on the shelf to sit the LP12 on. Once in place the level of the glass can be adjusted with the spikes under the Audiotech board. As the glass is perfectly flat levelling is easier.

Here's mine, before my last major deck upgrade.

I also tried removing the board and resting the glass on carbon fibre crosses.

I found this better than the board alone but not the board and glass for some reason, the glass was probably better isolated with the cups and balls.

Anyway a little food for thought.

Electronic is the best way to go for levelling the LP12

Dektop,

Are you sure that it is nearness to "level" that effects the sound of your LP12?  Could it be that small adjustments make a difference in the mechanical vibration interface between shelf and rack?  It looks like you may have a four point support.  If these are not perfectly set, perhaps a small amount of "micro-rattle" can occur, which would affect the sound significantly.

Charlie

count.d posted:

Corry posted:

Good advice. All of the levels I’ve used are off by a hair, and so I’ve long been in the habit of flipping them around and watching for the point where the error becomes symmetrical. I have one of those circular Mana levels, and it’s slightly off too, easily demonstrated by just rotating the platter while it’s in place. I suspect the silkscreened logo on one side is dragging it down.

Colm

This would not necessarily show that the spirit level is off. The platter could never be totally 100% level as it spins, otherwise it would be jammed in the bearing. The platter assembly is not level as it spins anyway time.

Those small circular spirit levels could be extremely accurately made, but the small area they cover often makes them very inaccurate due to dust and uneven surface. The lathe turning lines on the LP12 platter are enough to throw these small levels out. 

Fair point about the small diameter of the level exaggerating errors due to imperfections, dust, etc. Perhaps they’re not a realistic way to level a platter. In the case of the one I have, no matter how it’s rotated, it always has a tilt in the direction of the label, relative to the opposite direction, leading me to believe that it’s not all that accurate.

I don’t understand this comment: “The platter could never be totally 100% level as it spins, otherwise it would be jammed in the bearing.” Assuming a level plinth, properly tuned springs, and a platter without eccentricities, surely a platter that’s starts rotating when it’s 100% level will stay that way, imparting completely even forces in all horizontal directions inside the bearing well? In saying this, I’m cheerfully ignoring the effect of a record playing on the platter. Even if the record is completely without flaw, the couple of grams effective weight on one side of the platter from the arm and cartridge may be enough to throw things off; which is another argument for favouring the plinth, in terms of levelling.

Colm

harlieP posted:

Dektop,

Are you sure that it is nearness to "level" that effects the sound of your LP12?  Could it be that small adjustments make a difference in the mechanical vibration interface between shelf and rack?  It looks like you may have a four point support.  If these are not perfectly set, perhaps a small amount of "micro-rattle" can occur, which would affect the sound significantly.

Charlie

+1. I strongly suspect that the culprit is either micro-rattle, or possibly some uneven tension in the shelf, created or exacerbated by a warped board.

You mention that a quarter of a turn has made the difference you're hearing. For comparison, it’s well known that the Mana glass must not only be level, but must be tuned by ensuring exactly equal contact between the glass and the four spikes supporting it. This is done by levelling the glass on three of the spikes, then tapping the glass while adjusting the fourth. Only when the glass makes a clear, resonant, bell-like tone is it in tune. The difference between “in tune” and “almost” is less than one sixteenth of a turn, and is easy to hear.

I know a lot of importance is attached to levelling –  it’s relatively easy to do, and easier to verify, so why not take care with it? And more recently, much has been made of optimal torque for speaker bolts and the like. But for certain components – spiked shelves and stands being obvious candidates – I think it’s worth taking care to ensure that all contact points are under identical pressure, whether via levelling or torque adjustment, and that there are no uneven forces being imparted, e.g. where a shelf is bolted to the wall.

Colm

CharlieP posted:

Dektop,

Are you sure that it is nearness to "level" that effects the sound of your LP12?  Could it be that small adjustments make a difference in the mechanical vibration interface between shelf and rack?  It looks like you may have a four point support.  If these are not perfectly set, perhaps a small amount of "micro-rattle" can occur, which would affect the sound significantly.

Charlie

I think 'micro rattle', as you call, is something I have come across. I check for this with the deck removed using a little upward finger-pressure in the spike areas to make sure no 'rocking' of the platform occurs. Then adjust as necessary.

Steve J posted:

dektop100 posted:

Last week the sound quality from my LP 12 feel apart. This wasn't the first time. From previous experience I knew this was likely to be due to something in the Audiotech wall shelf 'changing' .

dektop,

There is one thing that could be influencing the problem of levelling. I also have an Audiotech wall shelf, from the '80s, which is probably a similar vintage to yours. Over time the shelf board can warp and the slight sag could influence your results when trying to get things level. Aside from replacing the board, you can buy a replacement board from Tiger Paw, is to use Fraim glass and balls on the shelf to sit the LP12 on. Once in place the level of the glass can be adjusted with the spikes under the Audiotech board. As the glass is perfectly flat levelling is easier.

Here's mine, before my last major deck upgrade.

I also tried removing the board and resting the glass on carbon fibre crosses.

I found this better than the board alone but not the board and glass for some reason, the glass was probably better isolated with the cups and balls.

Anyway a little food for thought.

 

 

Your Audiotech looks a bit neater than mine. I had to have the spike-bushes replaced because they wouldn't allow 'tightening-up'. I've had stainless steel blocks machined, tapped and welded into the frame instead. My spikes are also wound down to a greater degree. I recently replaced the original top with a Tiger Paw one (thin-type) because it was getting very 'holed'. The deck doesn't have the trampolin.

Dektop and steve j,

If you feel like experimenting, I suggest you try replacing the upward facing spikes (under the wood shelf) with dome nuts.  You may need to use short studs, of the same thread as the spikes, with dome nuts firm against the rack below and dome facing upward to wood shelf.  In my experience a sharp point into wood makes for a slightly "grungy" mechanical interface, and which can degrade over time.  The dome or ball usually sounds better.  I cannot say if this would improve on the carbon "X" inserts - which address the same problem.

Using the four support points is problematic, as has been mentioned.  Domes or balls may be more difficult to adjust perfectly than are the points.  My best experiences have been using three supports, not four.

Another interesting experiment would be to try Naim Chips over the points, in the same roll as the carbon "X's" in Steve J's photo.  This business is tricky, and you must of course trust your ears.

Cheers,

Charlie