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EMT 927

kjt239 said:
There are of course many differences! First a "broadcast" turntable is built (as you say) for reliability, and so is built to precision industrial standards - like a cutting lathe (that everyone forgets about).

keith
Click to expand...

That's nice supposition regarding an EMT being as well made as a lathe, but sadly it's not backed up by their relative cost at the time of purchase or by any form of measurement.
 
A few points about Neuman lathes. They are not the same as a broadcast turntable, just share the industrial requirements pertinent to their application. (not the additional pressures brought on by commercial products which could reduce their effective performance).
Using a lathe as a turntable is OK but you still have the problem with the pickup and its arm, together with the mechanical (acoustic?) coupling between the arm and the turntable, which is an important part of the arm/pickup/turntable performance. This is then your problem, as against the solution presented by the manufacturer in a broadcast turntable.
The other point about a Neumann lathe is that it weighs a ton!

keith
 
Steely Dan..Aja. Now that is a track worth playing on an EMT. 'Gaucho' is another. I am very impressed by the sheer dedication of the people working on the EMT stuff. I pursue all things Voigt (corner horns) but one day I shall investigate the EMT deck, real German enginering. A thorens 224 is my great dream.....
 
Hi all! Some time gao there was a bit of controversy as to what kind of motor EMT 927 and 930 have.
All the signs on the earth and the sky suggested induction motor while one of the reputable EMT servicemen (HM)
kept telling me it is synchronous.
Here is one example of such statements from some (official??) leaflet at the site of another reputable serviceman:
www.emt-profi.de/Dusch-pdf/emt930-e.pdf
and one more:
http://www.google.com/url?sa=t&rct=...sg=AFQjCNHp_7CP0yvrTzLmmCeJKOt5aezO0w&cad=rja

I've recently came accross these articles by Mark Kelly, which may give a hint:

http://www.clarisonus.com/blog/?p=92
http://www.clarisonus.com/blog/?p=96

I have not done the generator test he describes in Part I as I do not want to mess my alignment again,
but a couple of symptoms coincide, suggesting eddy current induction motor:

-applying extra load by fingers slows the motor down
-big power: 30W 930 and IIRC 50W 927

Another symptom is the voltage-speed constant curve Kelly mentions in Part II. According to HM 930's motor "locks at" (provided this is indeed EC motor, most probably he means "maintains a constant speed down to") 90V. I have not checked that myself yet as my controller is still in statu nascendi.

On a related note here is an extract from VPI's SDS motor controller description:

"During motor startup, the SDS increases its output voltage in order to bring the platter up to speed quickly. Once the desired platter speed has been reached, the SDS ramps the output voltage down in order to reduce motor vibration and, therefore, the systems noise floor."

I'm wondering why lowering the voltage reduces the vibration? Although SDS is primarly for synch motors, if Kelly's observation of a constant spped vs voltage applies to EMT motors one may try the same with EMT, reducing the voltage from 210V to approx. 90V to see if there is any detectable reduction in vibration.

Cheers,
phi
 
phixphi said:
Hi all! Some time gao there was a bit of controversy as to what kind of motor EMT 927 and 930 have.
All the signs on the earth and the sky suggested induction motor while one of the reputable EMT servicemen (HM)
kept telling me it is synchronous.
Here is one example of such statements from some (official??) leaflet at the site of another reputable serviceman:
www.emt-profi.de/Dusch-pdf/emt930-e.pdf
and one more:
http://www.google.com/url?sa=t&rct=...sg=AFQjCNHp_7CP0yvrTzLmmCeJKOt5aezO0w&cad=rja

I've recently came accross these articles by Mark Kelly, which may give a hint:

http://www.clarisonus.com/blog/?p=92
http://www.clarisonus.com/blog/?p=96

I have not done the generator test he describes in Part I as I do not want to mess my alignment again,
but a couple of symptoms coincide, suggesting eddy current induction motor:

-pllying extra load by fingers slows the motor down
-big power: 30W 930 and IIRC 50W 927

Another symptom is the voltage-speed constant curve Kelly mentions in Part II. According to HM 930's motor "locks" (i.e. most probably he means "maintains a constant speed" if the motor is EC) at 90V. I have not checked that myself yet as my controller is still in statu nascendi.

On a related note here is an extract from VPI's SDS motor controller description:

"During motor startup, the SDS increases its output voltage in order to bring the platter up to speed quickly. Once the desired platter speed has been reached, the SDS ramps the output voltage down in order to reduce motor vibration and, therefore, the systems noise floor."

I'm wondering why lowering the voltage reduces the vibration? Although SDS is primarly for synch motors, Kelly's observation (provided EMT motors are EC) suggests one may try the same with EMT, reducing the voltage from 210V to approx. 90V.

Cheers,
phi
Click to expand...





nice

:)
 
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