[denverartist]

I have a turntable I built, which I will call a "Quasi-Linn" LP12. it is made from Linn platters, Linn sub-chassis, Linn bearing, and Linn motor with original Linn pulley. (The base, top and armboard are DIY).  I set it up with old-style  circuit - new capacitors, etc as in the original 1970s Pre-Valhalla tables.  I'm in US and I believe the motor is for North American turntables but it spins too fast - about 38 rpm on the platter (obviously out of range of any pulley-tilt adjustment or belt change).  I suspect this motor is only for Valhalla LP12s.  Voltage change doesn't affect the speed so it is either the pulley or the 50 or 60 Hz difference.   Motor # 9904 111 04802, printed 250-300rpm, 50 60 Hz.

Any advice about what I can do to get speeds to 33 1/3rpm? Thanks.

Pete

[FullRangeMan]

I not a expert but you are located in a 50 or 60Hz area ?
If the motor match your outlet cicling its something else.

[denverartist]

With advice from other sources I see I need a 17mm pulley. This one is 21mm for 1980s Valhalla tables.

Pete

[andyr]

With advice from other sources I see I need a 17mm pulley. This one is 21mm for 1980s Valhalla tables.

Pete

That doesn't sound right to me - if a 21mm pulley is pushing your platter round at 38rpm then a 17mm diameter pulley will push it round at 17/21 * 38 ... which is just under 31rpm.  NOT 33.3333333!

Then there's the issue of removing the current pulley from your motor and putting a new one on.  I suggest you will destroy the motor bearings, attempting to do this.     (Been there ... done that!    )

I suggest you need to contact a Linn dealer and buy a new motor appropriate for your country and your power.

Or buy an Edmund Chan DC motor and PS.

Andy

[planet10]

cool.

i have the same set of parts. A 50 Hz motor, i will need to buil/get a speed controller.

A controller probably the eay fix for denver.

dave

[andyr]

i will need to build a speed controller.

dave

I'm not sure you will be able to find a kit to build an AC motor speed controller?   

i have the same set of parts. A 50 Hz motor, i will need to get a speed controller.

As the Eagle/Roadrunner is no longer available ... I suggest the best choice is Edmund Chan's 'Mose/Hercules' - which is basically the Linn Valhalla ... extended to cover 45rpm as well.

Or his newer DC power supply (you'll need a new motor!).

Andy

[planet10]

I think that all that is needed is a sin wave generator with sufficient drive. Check diyAudio.com

dave

[Mike B.]

I have a MB 10 motor and the simple control board out of my LP 12. I replaced both with a Origin Live DC motor and Controller. It was stable at 33rpm

[denverartist]

Mike B - Do you have a motor with a 17mm pulley you'd sell?

Thanks
Pete

[Mike B.]

Mike B - Do you have a motor with a 17mm pulley you'd sell?

Thanks
Pete

PM sent Pete

[planet10]

This might be of interest. A speed controller designed to replace Valhalla:

https://www.diyaudio.com/forums/group-buys/349742-turntable-tachometer-motor-speed-controller.html#post6086530

dave

[puroagave]

This might be of interest. A speed controller designed to replace Valhalla:

https://www.diyaudio.com/forums/group-buys/349742-turntable-tachometer-motor-speed-controller.html#post6086530

dave

Thanks for the link! this looks like the answer to many prayers. A SOTA speed controller for the LP12 on the cheap.

[andyr]

Looks very good!   

Andy

[denverartist]

Thank you for that tip and link, Planet 10