Linn LP12 motor malaise ?

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Mozfet,

there is quite a row of maxons which can be used. All DC types can be considered but it is adviseable to use a motor with a higher max. supply voltage if a wide variety of speeds is desired.

I would avoid EC motors, they do not run as smooth as the DC motors, are more expensive, have twice the rotational inertia. I use a maxaon EC motor for a small, powerful milling and drilling machine, but not to drive a TT.

The maxon's speed goes linearly with supply voltage. If for instance the motor shall cover all speeds from 16 to 120 rpm and still have a tiny amount of speed headroom, then a 9 Volt/6000rpm version could cause you trouble to get a linear voltage regulator like LM317 or L200 or LT1085 properly working at 2 Volts for 33 rpm or 1 Volt for 16 rpm. Much better to use a 42V/6000rpm version; then you are most likely to get the reg working proplerly.

One thing, it is wise to choose a speed of 1200 or below for 33 rpm. This is 20Hz wobble frequency (the motor's shaft has wobble, even if this is only a few µm). Then for 45 and 78 rpm you have the wobble frequency in the audible range, but how many records are 45 and 78? If you do not need 16 rpm, you could go down to 600 rpm, but methinks the motor does not run that smooth at 600 and below 600 it becomes even worse.

The maxon i recently picked up has the code 2028.949-61.121-025 .

949 means this motor has a 42V winding.
But i guess that any 24 V (code 941) or 30 V (code 942) will do fine.

Please contact maxon ( www.maxonmotor.com ), they are helpful and cooperative and maybe you can talk them in mailing you a catalogue if you avoid to mention you need this catalogue to peg motor's type at thrift stores and do not intend to buy some new motor. :)
 
Goetz Wilimzig

Klaus,
where do I find the Verdier tuning articles from Goetz Wilimzig in the net ?
You better don't. From reading his article in SoundPractices #10, and from recalling his articles in "Das Ohr", i would consider GW as a guy showing how knowledgeable he is (and implicitely, how dumb a fool you are) and i sense the intention to keep the reader stuck in mystery. In the SP10 article he delivers a mixture of unbackupped statements and some evident truths.

Although i have professional education and practical experience in this field, i've got no clue how he came to his statements and figures in the tabular.

If i now look at the Verdier displayed in the SP10 article, i see magnetic tape (that's good, but for other reasons than those GW claimed) but i see no means of keeping the belt at a well defined tension. Which would have been sooo easy, look at the beautifully milled parts, no problem to let the motor sit on a sled with ball race and have a string and a weight pull the sled away from the platter spindle, thus keeping the belt tight. And if the weight is changed, the belt's tension is changed, too. Adjustable by ears an then remaining at that value for years.

What i read in this SP article is work of a sorcerer's apprentice IMO :mad: , no matter if this sorcerer's apprentice is permitted to put a "Dr." in front of his name.
 
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