Hi
Finally finished my motor controllers.Thanks Daniel for the help and excellent project.As well as rock steady speed I now have really quick start and stop and 45 rpm at the touch of a button for my Rega 24v motor.I can even play 78's using the 45 pully
I made two of these.One for a friend but he is short of cash now so If anyone is interested in the other for cost of parts please PM me
Rich
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Finally finished my motor controllers.Thanks Daniel for the help and excellent project.As well as rock steady speed I now have really quick start and stop and 45 rpm at the touch of a button for my Rega 24v motor.I can even play 78's using the 45 pully
I made two of these.One for a friend but he is short of cash now so If anyone is interested in the other for cost of parts please PM me
Rich
A JVC TT 81 would be worth a look. I am told it is related to the JVC cutting machine by the man who should know when at JVC. The L3E and 5E are cheaper versions. Belt drive has many problems that motors will not cure. It is almost the case that no 1960's bearing is out of date and that no belt is good enough. Out of Denon, Technics and JVC the latter were the experts. They also were important in pick up design. I fancy the L5E is better than SP10 to my ears. It looks like junk so has scope to be better. To my ears no DD problems unlike the 1210 that I still very much like.
I suggest you try one of Daniels controllers with a 24v rega motor and the thickest bearing oil your turntable will allow.
My lp12 bearing running 3K silicon oil offers stability that embarrasses many dd decks. It's all too easy to generalise about drive types, when it's all down to implementation.
My lp12 bearing running 3K silicon oil offers stability that embarrasses many dd decks. It's all too easy to generalise about drive types, when it's all down to implementation.
As said by Mr Verdier many years ago. He also liked the magnetic brake of the Garrard 401 for similar reasons as oil. Verdier felt that if drag could be for example 10 times that of stylus friction ( highly variable, dynamic wow ) the effect of the stylus can be minimised. For some reason JVC did a better job of DD without telling the world. Verdier disliked belts without having a better solution. His answer was a cord. My first ever high grade turntable was a ERA mk6. As far as I know one of his. My feeling is the Lenco is the best value high grade turntable. It's only defect of note helps it in other ways. That is where and how the motor is placed. In some ways the verve of a Garrard SP25 is to put an LP12 to shame. Belt drive is a way of making a very cheap drive system work. Alas the belt does the same job with stylus vibration as motor vibration. The quest for a good motor is thwarted by the belt. Happy Christmas everyone.
I try to make people think. The sad bit for me is few realte the technical to what they hear. I rearly get a return of serve. The new year truely happened on the 21st to 22nd, Happy New Year all the same. I suspect the one we use is based on Christmas. Christmas was predicted from the most likely point of conception ( when light and dark equal ), that's worse than some of my conjectures.
I spent 23 years of my life repairing things, that stopped in 1997. The time since then designing things. It gave me plenty of chanes to hear without buying. It makes a big difference. Simple designs with high grade parts always were impressive. Sometimes complex sounded good. That was very rare.
I spent 23 years of my life repairing things, that stopped in 1997. The time since then designing things. It gave me plenty of chanes to hear without buying. It makes a big difference. Simple designs with high grade parts always were impressive. Sometimes complex sounded good. That was very rare.
That's easy. When building a Linn LP12 power supply for a friend I was interested as to the phase angle on the blue phase ( 220 nF ). I was very surprised to find it wasn't a big deal so tried all options including 130VAC and 66VAC as per Lingo ( 66V not my taste, too thin ). The really big deal was the voltage ( 80 to 90 ). I had the phase capacitor so bad at one point that the plinth of the LP12 was vibrating, yet the sound was very OK.
The step that changed my thinking was inverting the LP12 outer platter to see the belt working. It was flapping in a very controlled way on the dreadful phase cap. This means the LP12 has a remarkable spring and belt set up for this problem. The next part of the understanding came from owning a Garrard 401. It is very much like the LP12 in the good and the bad of it. The bad is very small in my view. Better than LP12 is the solidity of images and a sound usually only heard on first class analogue tape decks. As someone said the LP12 sounds like a slightly drunk yet polished performer who never makes it obvious as he is a pro. The Garrard motor is about 20 times larger in power output if taking the Lingo solution and 16 watt ( 28 in reality ) Garrard motor. The Garrard is almost DD in how it works except to have the advantage of gearing. LP12 250 RPM , Garrard Circa 1350 ( 1/4 inch to 10 1/2 inch ), DD real speed.
It isn't a big leap to say the belt removing the flap vibation must also do the same to the LP vibrations. It isn't hard to come up with cures for this. Stiffer belt, better motor ( Old Papst ? ). More bearing drag. And the 1954 Philips idea of a belt tensioner. The idea that the flywheel is a cure seems not to be the whole story. My thinking is belt drive is for very cheap high quality turntables ( AR ). However to take it to the highest grade is very hard. Whilst DD's are not perfect they answer the question of Verve. The Lenco is near perfect. I suspect it could be made much better for very little money.
I have been using an LP12 for about a year now ( Ekos, DL110, own preamp ). It's great, still hear the drunkeness. Have a 401 I must build.
If the cut of an LP is played on it's cutting lathe the sound is more like a 401. The little JVC has a similar sound. My girlfriend has one I found. At times I am jealous. Unlike most DD's it has no obvious high frequency problems and an excellent midband. Even the arm is ultra solid. It looks awful and cheaply made, which it isn't.
Back to the vibrations on LP. These are not constant. Sometimes called dynamic wow when slowing slightly under load. If the speed when LP12 is checked at 66V or 130V there is no change in speed as it has a synchronous motor, yet the sound is very different. Thus the flywheel is not the store of energy for this problem. LP12 has a supurb flywheel and bearing if asking.
The step that changed my thinking was inverting the LP12 outer platter to see the belt working. It was flapping in a very controlled way on the dreadful phase cap. This means the LP12 has a remarkable spring and belt set up for this problem. The next part of the understanding came from owning a Garrard 401. It is very much like the LP12 in the good and the bad of it. The bad is very small in my view. Better than LP12 is the solidity of images and a sound usually only heard on first class analogue tape decks. As someone said the LP12 sounds like a slightly drunk yet polished performer who never makes it obvious as he is a pro. The Garrard motor is about 20 times larger in power output if taking the Lingo solution and 16 watt ( 28 in reality ) Garrard motor. The Garrard is almost DD in how it works except to have the advantage of gearing. LP12 250 RPM , Garrard Circa 1350 ( 1/4 inch to 10 1/2 inch ), DD real speed.
It isn't a big leap to say the belt removing the flap vibation must also do the same to the LP vibrations. It isn't hard to come up with cures for this. Stiffer belt, better motor ( Old Papst ? ). More bearing drag. And the 1954 Philips idea of a belt tensioner. The idea that the flywheel is a cure seems not to be the whole story. My thinking is belt drive is for very cheap high quality turntables ( AR ). However to take it to the highest grade is very hard. Whilst DD's are not perfect they answer the question of Verve. The Lenco is near perfect. I suspect it could be made much better for very little money.
I have been using an LP12 for about a year now ( Ekos, DL110, own preamp ). It's great, still hear the drunkeness. Have a 401 I must build.
If the cut of an LP is played on it's cutting lathe the sound is more like a 401. The little JVC has a similar sound. My girlfriend has one I found. At times I am jealous. Unlike most DD's it has no obvious high frequency problems and an excellent midband. Even the arm is ultra solid. It looks awful and cheaply made, which it isn't.
Back to the vibrations on LP. These are not constant. Sometimes called dynamic wow when slowing slightly under load. If the speed when LP12 is checked at 66V or 130V there is no change in speed as it has a synchronous motor, yet the sound is very different. Thus the flywheel is not the store of energy for this problem. LP12 has a supurb flywheel and bearing if asking.
Very interesting post, Nigel - my comments are interposed:
AIUI, it is not so much the value of this phasing cap which sets the phase difference between the red & blue wires on a Premotec but the fact that it is a cap ... hence delivers 90 deg phase difference.
Unfortunately, the optimum phase difference for Premotec motors - which produces the minimum motor vibration - is not 90 deg!
How do I know this? Bcoz for the last 12 months I've been running a prototype of the 'Number9' motor speed controller - which is about to have its Production release. This allows you to adjust the phase angle in 0.01 deg increments ... you simply hold the motor in your hand and adjust the phase angle - so you can feel when you have selected the right value.
The 'Number9' also allows you to increase the voltage being fed to the motor. My understanding is that Linn chose 80v for the Lingo in order to minimise motor vibration. The higher the voltage fed to the motor, the more it vibrates ... and because they were not using the optimum phase difference for the motor windings (as I said, not 90 deg), they had to reduce the voltage from the nominal 110v.
I agree the Lingo delivers thin sound - that's the penalty for low motor voltage! What Steve (the designer of the ' Number9') and I found is that increasing the voltage increases the motor's "drive" ... torque ... whatever - and this produces a definite increase in SQ. I'm feeding 30v to a 24v (Rega) Premotec atm - so equivalent to feeding 140v to a 110v (Linn) Premotec.
Absolutely agree - but you need to try an LP12 running a standard 110v Premotec at 140v ... when using a 'Number9' to get the phase angle optimised.
In my own " SkeletaLinn" I run 2 motors (the 'Number9' controls 2 motors independently, with a selectable phase angle between them) - and Steve and I reckon the result is almost DD in delivery!
With the 'Number9' I've always used silicone O-ring belts (D70) about the same circular diameter as a Linn flat belt. Have no idea whether they are in fact stiffer than a Linn flat belt ... or not. However, next experiment is to use a pair of 300rpm / 60Hz Hurst motors that Steve has located (not the ones that VPI use). These are double the horsepower of the Premotecs I've been using so, if the voltage experiments are anything to go by, they should deliver even better SQ than I'm getting at present.
Andy
AIUI, it is not so much the value of this phasing cap which sets the phase difference between the red & blue wires on a Premotec but the fact that it is a cap ... hence delivers 90 deg phase difference.
Unfortunately, the optimum phase difference for Premotec motors - which produces the minimum motor vibration - is not 90 deg!
How do I know this? Bcoz for the last 12 months I've been running a prototype of the 'Number9' motor speed controller - which is about to have its Production release. This allows you to adjust the phase angle in 0.01 deg increments ... you simply hold the motor in your hand and adjust the phase angle - so you can feel when you have selected the right value.
The 'Number9' also allows you to increase the voltage being fed to the motor. My understanding is that Linn chose 80v for the Lingo in order to minimise motor vibration. The higher the voltage fed to the motor, the more it vibrates ... and because they were not using the optimum phase difference for the motor windings (as I said, not 90 deg), they had to reduce the voltage from the nominal 110v.
I agree the Lingo delivers thin sound - that's the penalty for low motor voltage! What Steve (the designer of the ' Number9') and I found is that increasing the voltage increases the motor's "drive" ... torque ... whatever - and this produces a definite increase in SQ. I'm feeding 30v to a 24v (Rega) Premotec atm - so equivalent to feeding 140v to a 110v (Linn) Premotec.
Absolutely agree - but you need to try an LP12 running a standard 110v Premotec at 140v ... when using a 'Number9' to get the phase angle optimised.
In my own " SkeletaLinn" I run 2 motors (the 'Number9' controls 2 motors independently, with a selectable phase angle between them) - and Steve and I reckon the result is almost DD in delivery!
With the 'Number9' I've always used silicone O-ring belts (D70) about the same circular diameter as a Linn flat belt. Have no idea whether they are in fact stiffer than a Linn flat belt ... or not. However, next experiment is to use a pair of 300rpm / 60Hz Hurst motors that Steve has located (not the ones that VPI use). These are double the horsepower of the Premotecs I've been using so, if the voltage experiments are anything to go by, they should deliver even better SQ than I'm getting at present.
Andy
I'm happy with my looks like new 1989 LP12. I never updated it above the glued chassis point as the drive system is not good enough. I heard the later LP12 a year or two ago and realised it has moved nearer to lets say the Lenco sound. Cost says Lenco is the better option, even the Lenco arm is OK for entry level PU's.
I measured the LP12 motor as a current waveform. From memory about 10% THD. This is what needs to be better if vibration is to be far lower. I did consider recording the waveform and then constructing a mirror image version as if the output of negative feedback. As the wave is repetetive any full wave sample would be enough. This is called predistortion. If a square wave is fed to the LP12 motor the current waveform looks very similar. Both look like triangle waves. Even Valhalla is only 0.05%THD at the drive end so not the reason for doubt ( voltage waveform ). This sort of suggests the predistortion won't do much, without trying it is hard to say. This motor is a resonant device which for normal mains helps, for improved power it holds it back. Valhalla's 47 uF 250V are too small and 220 uF works better ( Hetrodynes of mains and 50Hz at circa - 40 dB, - 57 dB at 220 uF ). A floating 230 or 115 V gets 6 dB when worst case. In the UK 110V is cheaper to buy as a rule and Valhalla has the option. Centre grounding ( 55-0-55 ) makes it worse!
The Lenco motor at my best guess is 0.5% THD current wave distortion. The Garrard 501 is < 0.1% at the third harmonic which includes all distortions of the power unit. The 2nd is less than 1%, this is a good trade off as this type of vibration is almost unimportant and does not show in the -79dB weighted rumble ( LP12 about -72 dB ). A very good Garrrard 401 is about -60 dB, the 501 has the same drive system. This shows attention to detail pays off. I doubt the LP12 would show +/-3 dB regardless of trying very hard. The 501 idler is nearly solid as are it's motor mountings ( pure madness to do that, worth it ). If the mounting of a 401 were made solid I suspect the -60 dB would not be possible. The 501 motor is built in house. The 501 prototype had a 301 motor. It was good for two weeks before noise showed up even after a careful rebuild. The 501 looked at that problem and cured it. To my astonishment the Lenco is good in this regard. However the Lenco makes new problems with it's solution. I could live with that.
I measured the LP12 motor as a current waveform. From memory about 10% THD. This is what needs to be better if vibration is to be far lower. I did consider recording the waveform and then constructing a mirror image version as if the output of negative feedback. As the wave is repetetive any full wave sample would be enough. This is called predistortion. If a square wave is fed to the LP12 motor the current waveform looks very similar. Both look like triangle waves. Even Valhalla is only 0.05%THD at the drive end so not the reason for doubt ( voltage waveform ). This sort of suggests the predistortion won't do much, without trying it is hard to say. This motor is a resonant device which for normal mains helps, for improved power it holds it back. Valhalla's 47 uF 250V are too small and 220 uF works better ( Hetrodynes of mains and 50Hz at circa - 40 dB, - 57 dB at 220 uF ). A floating 230 or 115 V gets 6 dB when worst case. In the UK 110V is cheaper to buy as a rule and Valhalla has the option. Centre grounding ( 55-0-55 ) makes it worse!
The Lenco motor at my best guess is 0.5% THD current wave distortion. The Garrard 501 is < 0.1% at the third harmonic which includes all distortions of the power unit. The 2nd is less than 1%, this is a good trade off as this type of vibration is almost unimportant and does not show in the -79dB weighted rumble ( LP12 about -72 dB ). A very good Garrrard 401 is about -60 dB, the 501 has the same drive system. This shows attention to detail pays off. I doubt the LP12 would show +/-3 dB regardless of trying very hard. The 501 idler is nearly solid as are it's motor mountings ( pure madness to do that, worth it ). If the mounting of a 401 were made solid I suspect the -60 dB would not be possible. The 501 motor is built in house. The 501 prototype had a 301 motor. It was good for two weeks before noise showed up even after a careful rebuild. The 501 looked at that problem and cured it. To my astonishment the Lenco is good in this regard. However the Lenco makes new problems with it's solution. I could live with that.
Very interesting post, Nigel - my comments are interposed:
AIUI, it is not so much the value of this phasing cap which sets the phase difference between the red & blue wires on a Premotec but the fact that it is a cap ... hence delivers 90 deg phase difference.
Unfortunately, the optimum phase difference for Premotec motors - which produces the minimum motor vibration - is not 90 deg!
How do I know this? Bcoz for the last 12 months I've been running a prototype of the 'Number9' motor speed controller - which is about to have its Production release. This allows you to adjust the phase angle in 0.01 deg increments ... you simply hold the motor in your hand and adjust the phase angle - so you can feel when you have selected the right value.
The 'Number9' also allows you to increase the voltage being fed to the motor. My understanding is that Linn chose 80v for the Lingo in order to minimise motor vibration. The higher the voltage fed to the motor, the more it vibrates ... and because they were not using the optimum phase difference for the motor windings (as I said, not 90 deg), they had to reduce the voltage from the nominal 110v.
I agree the Lingo delivers thin sound - that's the penalty for low motor voltage! What Steve (the designer of the ' Number9') and I found is that increasing the voltage increases the motor's "drive" ... torque ... whatever - and this produces a definite increase in SQ. I'm feeding 30v to a 24v (Rega) Premotec atm - so equivalent to feeding 140v to a 110v (Linn) Premotec.
Absolutely agree - but you need to try an LP12 running a standard 110v Premotec at 140v ... when using a 'Number9' to get the phase angle optimised.
In my own " SkeletaLinn" I run 2 motors (the 'Number9' controls 2 motors independently, with a selectable phase angle between them) - and Steve and I reckon the result is almost DD in delivery!
With the 'Number9' I've always used silicone O-ring belts (D70) about the same circular diameter as a Linn flat belt. Have no idea whether they are in fact stiffer than a Linn flat belt ... or not. However, next experiment is to use a pair of 300rpm / 60Hz Hurst motors that Steve has located (not the ones that VPI use). These are double the horsepower of the Premotecs I've been using so, if the voltage experiments are anything to go by, they should deliver even better SQ than I'm getting at present.
Andy
Yes all these motors are different I have done more then 250 Thorens TD160 motors for tuning on min.vibration some are the same but most times the phase cap need individual tuning. A two phase supply is the best solution.
There are a wide range of motor control units for synchronous motors, of those I know provide the topology of Dr. Fuß (sine wave oscillator based on SVF) best sonic results - go to post #12 under
Homebrew Motor Control Linn LP12 - Circuit Description wanted for Sine Wave Osc.
for the impressions while a listening test and #16 for the associated schematics.
I would be interested in how the difference is while listening against Meldano's ac controller is. Maybe one of the members know both.
Check also this thread:
Linn Lingo vs. Dr. Fuß or Square-Wave vs. Sine Wave Oscillator for Motor Control
P.S.:I am looking for the schematic of this Hercules motor control unit:
…and Steve says… Breathing Life into an Old Linn LP12 – The Hercules II and Mose + Hercules Power Supplies - Positive Feedback
Linn LP12 motor stutters at startup (reaches speed)- Vinyl Engine
As said before the motor current waveform is dominant. The sine wave is very like baby food. It can not add vibration if pure, like babies it isn't really required. Valhalla in later types was 0.05% THD ( current use 10 % THD ? ) . The only error is phase shift of the 0.22 uF. Voltage and PSU ripple matter most. Valhalla will work on pure DC. That can't be a bad idea? Why not 12V to 300V SMPS boost converter for $10? The 30 kHz or whatever needs to be kept away from other things.
I read a war time engineering report on the RR Merlin engine. It should be a very bad engine. It wasn't because RR knew what worked. The crank was too fragile by analysis. It wasn't because the link to the propellor was harmonically tuned. The Merlin is very crude in places. That saved weight if my guess is right. I suspect the output gearbox was exchanged in the routine servicing. It was OHC mostly to get good filling of fuel ( I totally doubt that ). They did it because they could is my guess. RR could not cast cylinder blocks as easilly as Ford V8 flat head. That's because Ford had 99% rejects at first. RR went half way on that. Most RR staff were unskilled. RR trained them !
Electronics was next to Marine Diesel engines in our library. I read vibration of diesel engines for fun. Section 621 in UK libraries in the past. Even now I would guess?
The reviewer liked the Napier Lion best. Alas none were taken to 2000 BHP. This was 1943 and used DB 601 as reference. RR exhausts were very expensive to make. The materials could be reused so no problem. Noise, thrust, drag compromise. Reading aero engines helps as like LP they are not great engineering until understood. Personally I feel the Napier Lion was better, it's designer went to RR.
I read a war time engineering report on the RR Merlin engine. It should be a very bad engine. It wasn't because RR knew what worked. The crank was too fragile by analysis. It wasn't because the link to the propellor was harmonically tuned. The Merlin is very crude in places. That saved weight if my guess is right. I suspect the output gearbox was exchanged in the routine servicing. It was OHC mostly to get good filling of fuel ( I totally doubt that ). They did it because they could is my guess. RR could not cast cylinder blocks as easilly as Ford V8 flat head. That's because Ford had 99% rejects at first. RR went half way on that. Most RR staff were unskilled. RR trained them !
Electronics was next to Marine Diesel engines in our library. I read vibration of diesel engines for fun. Section 621 in UK libraries in the past. Even now I would guess?
The reviewer liked the Napier Lion best. Alas none were taken to 2000 BHP. This was 1943 and used DB 601 as reference. RR exhausts were very expensive to make. The materials could be reused so no problem. Noise, thrust, drag compromise. Reading aero engines helps as like LP they are not great engineering until understood. Personally I feel the Napier Lion was better, it's designer went to RR.