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Old 7th November 2013, 06:23 PM   #1
Jay1234 is offline Jay1234  United Kingdom
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Default Power for an LP 12

Hello All,

Does anyone know If an LP 12 will run without its Valhalla / Hercules / Lingo Power supply ?
ie just with a couple of capacitors ?

If so how is the speed maintained accurately ?

Jay
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Old 7th November 2013, 07:41 PM   #2
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How about a DIY Armageddon:

DIY Geddon - LP12 power supply - pink fish media

jeff
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Old 7th November 2013, 08:07 PM   #3
Jay1234 is offline Jay1234  United Kingdom
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Thanks Jeff,

For the link I will most certainly be checking this out. I knew of the Armageddon but always thought it to be as complex as the the Valhalla board.

If Naim can design a power supply for the LP 12 as simple as this why didn't Linn do something similar.

Can I ask one question, dose this circuit hold the motor / deck speed stable

Jay
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Old 7th November 2013, 08:23 PM   #4
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Quote:
Originally Posted by Jay1234 View Post
If Naim can design a power supply for the LP 12 as simple as this why didn't Linn do something similar.
That's a good question. Why don't you ask them, I'd love to read their response.

Quote:
Originally Posted by Jay1234 View Post
Can I ask one question, dose this circuit hold the motor / deck speed stable
Yes, the AC synchronous motor will "lock on" to the mains frequency.

Synchronous motor - Wikipedia, the free encyclopedia

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Old 7th November 2013, 08:35 PM   #5
Jay1234 is offline Jay1234  United Kingdom
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Jeff,

You just know your NOT going to get an answer from Linn about this....

But thanks so much for a very simple answer & great link.

I know of an LP 12 really quite close to me (& silent as it's Valhalla recently died RIP ) thats going to be Gedded soon.

Jay
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Old 7th November 2013, 09:57 PM   #6
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Quote:
Originally Posted by Jay1234 View Post
I knew of the Armageddon but always thought it to be as complex as the the Valhalla board.
There's NOTHING complex on the Armageddon. It's almost as simple as the LP12 BASIK PSU,
which the LP12 came with as standard (noth Valhalla and Lingo as an option).
This Basik PSU is basically the same as on any other turntable with an AC syncronous motor,
such as Rega, Thorens and some dozens more. It contains two resistors and two capacitors,
to decrease voltage and generate the phase shift.

Linn LP12 Basik:

Click the image to open in full size.

an earlier one:

Click the image to open in full size.

Not to forget, the former Linn entry-level table called "Linn Basik" (~1990) had a similar PSU.
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Old 7th November 2013, 10:05 PM   #7
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Quote:
Originally Posted by Jay1234 View Post
I know of an LP 12 really quite close to me (& silent as it's Valhalla recently died RIP ) that's going to be Gedded soon.
That's the perfect way to buy a late 80's pre Cirkus Valhalla deck. Just don't tell the owner the Valhalla can be fixed with $20 worth of caps and resistors.

Post up a pic for us when you have it in hand.

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Old 7th November 2013, 11:01 PM   #8
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Default Variations

I've found there's a lot of discussion on various sites about the 'geddon PSU. A few interesting ideas:

1- Tweak the running voltage of your motor to find the voltage that achieves minimum vibration. Some writers suggest removing the motor and holding it to feel the minimum vibration. Your test range could be 84 to 60 Volts. Some diy’ers say 72V is ideal, some 64V, others in-between. When you get your first approximation, fine tune the phase shift as well, to optimize entire “run” circuit, i.e., two voltages approximately equal, one 90 degrees shifted from the phase of the other. Adjust phase shift capacitor as needed, realizing correct value may be 0.18 uF – 0.22 uF. Use your scope if you have one to determine 90 degree point.

2- Add a varistor and/or an inline mains filter. (Not sure if either is needed).

3- Install a 10nF, 600v capacitor in series with a 100R, 0.5W resistor across each pole of the switch to eliminate switch on/off thumps.

I’ll build one for my TT when I can. Right now I’m too thick into studies (a return to grad school, retooling for a new career).
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Old 8th November 2013, 08:12 AM   #9
Jay1234 is offline Jay1234  United Kingdom
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Hi All,
& thanks for all the info,

It's my understanding that the Armageddon had a large isolation transformer.
& thats what increases the cost.
Check this out..
*
pink fish media
DIY Geddon - LP12 power supply

all you need to know about Naim clone psu for LP12

Jay
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Old 8th November 2013, 09:45 AM   #10
andyr is offline andyr  Australia
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Quote:
Originally Posted by Jay1234 View Post

Does anyone know If an LP 12 will run without its Valhalla / Hercules / Lingo power supply?
ie. just with a couple of capacitors ?

If so how is the speed maintained accurately ?

Jay
I thought I'd extend what others have said.

The LP12 motor has 4 wires - 2 grey, 1 red and 1 blue. The original LP12 PS was simply a series resistor to reduce (UK) mains voltage to around 110v, plus a 220nF cap to provide a phase difference.

IOW, you don't need a Valhalla / Lingo / Hercules / Armageddon to drive an LP12. But some of the above give you 45rpm, as well as 33.

The resistor (10K in my case, in Oz) goes in series with the 2 x grey wires and the cap goes between the blue and the red wires. The LP12 will sound pretty damn good with this basic PS - because the motor has great torque, because it's being fed direct from the mains ... not as an output from a sine-wave generator. However, the Lingo provides some supposed sophistication because (as well as giving 45rpm) it reduces the voltage getting to the motor, once it's up and spinning, which reduces the vibration generated in the motor.

And the speed is maintained by the mains frequency.

Regards,

Andy
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