Hifitime
y.s.: >>>...the motor bearing was destroyed from the junk tight rubber band belt the dealer used<<<
Now what 'table would that have been, I ask?
To get a belt THAT tight, the motor if it was out-board would simply fall over, or?
BUT, if not out-board --- well that's another story. So before I go on, can we hear about this tt by any chance.
Thanks, |
Hi,
having read further through this thread one thing comes to mind: The actual length and shear thickness, mostly width of the belt in use.
Some say that this is of quite some importance and actually kept the belt VERY short (pulley under the platter) and beefy, (not thin, round or square) like the flat belts e.g. SME and Linn use.
Then there is the motor controllers, done over a number of times by Linn, and at least once by SME.
Listening to a thin (square) belt of a top Pro-ject table and thin (round) on TransRotor Z3 (sans controller) and then a short (flat) belt with controller on SME gives a pretty clear indication of the difference in transience/attack.
So much so, that on VERY dynamic vinyl the LP seems to 'slip' on the platter (rather then the belt) in the case of the SME -- if the LP is not fixed with the clamp provided.
This raises the question of 'slippage' of the vinyl on the platter in the case high torque direct OR belt drive, and if no platter clamp is used or even available.
Lastly, if the drive is THAT tightly coupled, then the motor controller's performance comes a LOT more to the fore. With the hole drive line becoming so much more unforgiving with next to no measurable 'slip' it is now unable 'paint over' some dynamic problem passages'.
Fix one thing, and it will reveal the next issue for sure.
Too much platter weight (never mind just the main bearing implications) in such a 'tight coupled' scenario may just 'over-load' the motor/controller, running behind torque demand and its reverse, producing delay and over-shoot if the platter's inertia is out of tune with the motor's torque delivery and the controllers feedback loop speed.
All this can explain why a more 'benign' coupling might sound better or more natural, even if slightly less 'dynamic'.
Greetings, |
Hiho :-)
y.s.: >> Enough with wimpy toy motors already! <<
I guess you are fully aware that this type of wimpy motor is supposed to do the same thing as a soft (and long?) belt already. 'Mellow out' any kind of speed variation that's occurring. It screws the dynamics but it sure will be 'smooth'.
Greetings, |
Buconero117,
>>>... the cat will keep chasing its tail <<<
And so the cat is having some entertainment, what's wrong with this?
Cheers,
PS: by the way, I just like how SME tts go about it, a belt drive with dynamics! -- that's why I got one :-) |
Interesting this inertia talk.
That raises the (old?) question who should control the STEADYNESS of speed - inertia of the platter, or the motor AND IT'S CONTROLLER.
If the motor sux, or the controller sux, you have to look back to the platter's inertia. If you manage to make it THAT heavy (never mind the resulting bearing problems) there must come a point where any conceivable variation in friction-changes of the needle to vinyl interface become SO SMALL as to approach zero.
I have a notion we have to look for some mighty heavy platter to get there. One expert put two Micro-Seiki on top of each other --- and then waits 5 minutes for the darn thing to stabilize the speed.
You see, we are now starting to move big-time out of the practical useful user-application --- which in turn also sux.
So it's back to the more practical idea as was mentioned above platter-weight not much more then ~ 4.5kg, still using a belt for a tiny bit more forgivingness, than a DD which translates its little faults too immediate into the speed stability.
Lastly a motor / controller package with the best available feedback speed / loop to mankind :-)
A thing to note: that bearing friction has to be present at a controlled level to "damp" the controller feed-back loop, preventing feed-back resonance, so to speak.
Now have a look who is doing something like this, and I guess you'd have a 'best of breed' and still user friendly tt.
Greetings, |
Hi,
all said sound fine, -- BUT there is clearly a difference between colouration and dynamics!
The platter material / mats / pads / and other damping are ALL colouration items (excluding some really heavy lead-loaded mats adding more mass)
The drive-line performance is an issue with dynamics / timing / rhythm etc. I don't think both should be just dumped into on pot so to speak.
Axel |
Albertporter
thanks for at least questioning, that dynamics are not quite the same a colouration.
I yet have to hear a system sounding more on-the-point/dynamic as is with a 'harder' connected drive, by simply using a different platter or platter-mat.
That's wishful thinking to me.
It can sound 'cleaner' and may leave this impression? But lack of 'slam' and 'drive' is more related to the drive then a platter-mat, in my current experience. |
Hiho,
you reflect my own listening experience and thank you for sharing your own findings on that.
Even with quite, or REALLY powerful motors like I've heard on an Transrotor Z3 or on a Thorens 2010 (motors where modified, with beefed-up controller power-supplies), due to the long thin belts they remained still more laid-back then e.g. my SME, even though one could notice some improvement in the dynamics department. Two motor yet did a little more but still just don't seem to get there.
Problem with a lot (more affordable?) DD's is the 'affordable' motor/controller as I understand it. It seems VERY difficult to get this completely right, because of the DD's 'unforgiving' 1:1 coupling.
Despite some of the ~ strange Linn 'behaviours' (some love it some don't), I think they got the motor to platter coupling just right I.E. sub-platter, short belt, powerful enough motor.
SME I think went a step further, smallish as the Papast-motor is, it pulls like a train, has a lot of torque --- BUT they had to spend some time and money on a very good motor-controller without it, it would NOT work.
The spec.: Reference oscillator is a 10Mhz quartz crystal, multiplied by 4 to obtain 40Mhz microprocessor clock speed. Driver stage has CMOS buffers/MosFet drivers with 1.2 Amp peak drive capability.
Power output stage is six high power complimentary MosFets in a 3 Phase Bridge Driver configuration.
Close loop speed control is implemented using pseudo sine wave commutation sequence and a proportional-plus-integral (PI) algorithm.
So, there you go. This is not some wall-wart using the power-line cycle for speed control. With a long 'forgiving' belt it will work fine, but the closer you get to 1:1 drive-line coupling the more need to have a close to cog-free drive with torque to boot.
Greetings, |
Atmasphere,
hope I don't sound boring by now?
Ever bothered to look at that funny platter-pad material of the SMEs at all?
Re: >> I find it astonishing that platter pads have received little or no attention in the last 2 decades <<
Not so, I'd say.
Bonded copper-pad of TW, bonded vinyl-pad of TransRotor, bonded cork-pad by Acutus, bonded glass by Brinkmann, non-bonded felt by Linn :-), etc. those are all pads on the platter, even though they are bonded except Linn.
Does that make the difference with your definition?
Axel |
Mark,
since you ARE in the know about PL(L), servo loops, 3 phase conversion, quartz reference, current supply ability, and on.
Have you any comment on the SME controller implementation, from what I posted earlier or any of your own more detailed insights?
Axel |
Hiho,
well, well, well.
What you seem to overlook is the reality of it all. Just have a look at HOW MANY tt manufacturers use exactly that 'rubbished' approach and then ask yourself why.
I think a STABLE AC motor (not DC which is prone to drifting) is just cogging, some more, some less, even 3 phase, and so along comes the soft, long, or what ever, belt to 'fix' it. At the same time mass is added, has to be added to the platter, to counter act the soft belt drives lacking dynamic performance.
Practically ALL tt's that make the top grades (Hi-End rating > 100 points) in all known to me German Audio Magazines are designed that way.
Then a 'controller' may be added (in some cases more of the name then the real thing), at extra expense.
The question: how much does one actually hear the difference?
Point to add: it was one of these 're-worked' Garrarde's (by Loricaft) the wound up pretty much on top of the heap. It was superior DYNAMIC performance that did it to the testers... alas not the high price with some questionable suspension on squash-ball, and other sundry items.
Greetings, |
Hiho,
y.s:
>> I rather have a better stronger motor to get the dynamic I want than to get it from a high mass platter <<
As you have noted I am with you actually. BUT without (and I said it much earlier) a VERY! good motor controller your wish is not going to be much of an improvement over a high mass platter - maybe quite the opposite!
The same applies to DD tables if not even more so.
Hard drive-line + so, so, controller = incoherent sound.
There are hardly any VERY good motor controllers commercially offered for all I know. So be careful what you wish for.
To my knowledge there is nowhere near close a solution, even with 'upper-class budget' , to replace soft belt and mass platter -- also supported by my mentioning these Audio magazines.
But if you are fine blowing ~ 25k plus, then you might even get a decent controller with a lighter = more dynamic! platter.
Therefore my point = simply - a Reality-Check!
Greetings, |
Lewm,
that 'Clear Audio' magnet repulsion is comprised of two ring-magnets ~ 2 1/2" outer diameter and ~ 1/4" in of magnet width. They then replaced the centre bearing pin with a ceramic pin (as you noted, I think). All it now does is not sit on a tungsten ball down the bearing well, but ALMOST float - presto.
This system is pretty much the same thing also use with the 'Pro-Ject 10' and some others like Transrotor that sells it as an upgrade purchase for e.g. the Fat Bob and Z3 etc.
This is in COMPETE contradiction to the 'Platine Verdier' tt which on purpose applies a constant bearing friction-load to stabilise their high-mass platter.
From experience I can tell, that the SME motor/controller is loop-locked much quicker when a small degree of friction is present. In fact if the controller is still trying to lock (can see on the controller's light indicator) and you only put the stylus in the start groove - voila, it's locked!
The looser the bearing the longer it takes the controller to lock (SME main-bearings are conical and can be adjusted for more or less friction)
Go figure...
Axel |
Lewm
what Quiddity is relating, as I seem to understand it, is that eddy current 'friction' is very much on the minimal side with the magnetic repulsion, almost levitation, ring magnet concepts. Also recall those magnets are only about 1/4" wide rings. To support this, it is told, that if these platter are (disconnected from the drive) pushed by hand seem to run 'forever' and thereby VERY MUCH differently behaving the 'Platine Verdier' mentioned by example.
Now go figure yet some more ... :-)
Axel
PS: a difference in VFT of .75g, now I'm running at 0.75g with an Empire S1000ZE/X (0.25g! - 1.25g spec) as compared to 1.5g spec. for a 'M20FL super' give the my controller a lot more 'pain in the a...' - it take just longer to settle. This is for me a clear indication about what friction (needle and/or bearing) does in terms of motor/controller loop-feedback/response... |
Lewm,
I know it's more PT to wire it up, but most of these switches work with a relay. Press once it comes in (switches on), press again it trips (switches off) :-)
Have fun, |
