I guess the simplest solution would be to try finding a 50Hz
motor. Check out what a spare motor would cost, although it
would probably be quite expensive. A better way may be to
track down a whole TT that somebody doesn't use anymore.
If you get a functional one cheap, then fine, otherwise, if it
is not working but the motor is OK, then you can probably make
a good deal.
Other alternative, build an electronic motor control.
motor. Check out what a spare motor would cost, although it
would probably be quite expensive. A better way may be to
track down a whole TT that somebody doesn't use anymore.
If you get a functional one cheap, then fine, otherwise, if it
is not working but the motor is OK, then you can probably make
a good deal.
Other alternative, build an electronic motor control.
Freq. converter
Hi,
I've found this in another thread:
Quote
A simple Wien-bridge using opamp (1/2 of 5532) and a pair of low power PNP/NPN transistors driving a step-up ( 10:200) transformer. The dc supply to the opamp and PNP/NPN is +/- 15 volt.
The output frequency is adjusted to 50 Hz by adjusting the R in the RC Wien-bridge. The output voltage is adjusted to 110 volt by adjusting the R in the amplitude-ratio (R-ratio) of the Wien-bridge. The output power is about 1 to 1.5 watt which is enough for the TD160 motor.
The output waveform is as sinusoidal as my signal generator and is very stable. TD160 runs happier with this electronic 50Hz supply than a raw 50 Hz supply. It does give a better sonic effect to my system.
Unquote
MAybe this is my solution!! Does anyone know how this works? Any scheme? What is a Wien-bridge?
Thanks
Hi,
I've found this in another thread:
Quote
A simple Wien-bridge using opamp (1/2 of 5532) and a pair of low power PNP/NPN transistors driving a step-up ( 10:200) transformer. The dc supply to the opamp and PNP/NPN is +/- 15 volt.
The output frequency is adjusted to 50 Hz by adjusting the R in the RC Wien-bridge. The output voltage is adjusted to 110 volt by adjusting the R in the amplitude-ratio (R-ratio) of the Wien-bridge. The output power is about 1 to 1.5 watt which is enough for the TD160 motor.
The output waveform is as sinusoidal as my signal generator and is very stable. TD160 runs happier with this electronic 50Hz supply than a raw 50 Hz supply. It does give a better sonic effect to my system.
Unquote
MAybe this is my solution!! Does anyone know how this works? Any scheme? What is a Wien-bridge?
Thanks
Easiest solution is probably to change the pulley to one for 50Hz. Very likely the motor can be set to work at 220v. That said you'll get a much improved sound if you build a low-distortion oscillator. Wien bridge is fine if you don't mind lo-tech and don't require a variable frequency. Any electronics textbook will teach you how to calculate the values. Use low pass filter and a chip-amp/STK module before the transformer. This was the first PS i built and it still works fine. Then i got a bit more enthusiastic and replaced the Wien bridge with an 8015 AVR which generates the sine out of a look-up table, then a DAC and a more complex lo-pass. Is it worth the trouble? Probably not as then you have to deal with filtering digital noise as well.
cheers
peter
cheers
peter
And another thing. The example above with the 5532/complementary pair is not a very good idea. You should get as high an output voltage as possible before the step-up transformer. This will alow you to use a step-up with a low ratio and minimise the transformer distortion.
The digital approach also allows for easy generation of a second phase-shifted wave if you decide to drive each winding of the motor directly instead of relying on the capacitor.
cheers
peter
The digital approach also allows for easy generation of a second phase-shifted wave if you decide to drive each winding of the motor directly instead of relying on the capacitor.
cheers
peter
Raka said:
Have you checked SAIA synchrone motors? Maybe they'll fit? Check SAIA's website.
Which speed? Is it 250 rpm (24-pole)? Could also try this (just the motor).
http://www.elfa.se/elfa/produkter/se/20/2006853.htm?_54_490_12
Pulley dismountling
Thanks for the links
If I decide to change the pulley, I'll have to dismount the pulley from the original motor, won't I? I tried to do it with a tape deck motor lying around, thinking that the pulley system would be the same, and I couldn't. I didn't see anything to catch, no screws. I tried and tried, but all I got was a broken rotor.
Does anyone know how to do this with a thorens motor?
Thanks for the links
If I decide to change the pulley, I'll have to dismount the pulley from the original motor, won't I? I tried to do it with a tape deck motor lying around, thinking that the pulley system would be the same, and I couldn't. I didn't see anything to catch, no screws. I tried and tried, but all I got was a broken rotor.
Does anyone know how to do this with a thorens motor?
I don't know about this particular motor, but my experience suggests that the pulley was probably "heat shrunk" onto the shaft.
I so, you'll have to cut it off, as heating may damage the motor.
Fitting a new one won't have the same problem. You can heat the pulley alone, then drop it onto the shaft. Make sure to get the position exact - no second chance.
Good luck.
I so, you'll have to cut it off, as heating may damage the motor.
Fitting a new one won't have the same problem. You can heat the pulley alone, then drop it onto the shaft. Make sure to get the position exact - no second chance.
Good luck.
Lucky this time
Yes, I was because the pulley has a couple of screws and goes out easily. One point for Thorens!
All I have to do now is to discover the poles must have the spare motor.
Nevertheless, the wien bridge is appealing to me. Why the 5532 is not a good solution? I have to step up to 110V so a 10:1 ratio will be enough. Has anyone implemented this option?
Yes, I was because the pulley has a couple of screws and goes out easily. One point for Thorens!
All I have to do now is to discover the poles must have the spare motor.
Nevertheless, the wien bridge is appealing to me. Why the 5532 is not a good solution? I have to step up to 110V so a 10:1 ratio will be enough. Has anyone implemented this option?
Thorens do provide pulleys for 50/60Hz operation. It's a very simple procedure to replace for any user. Of course the sine oscillator is the better option as it will improve the sound considerably. Yes, i have tried it on my ex- Thorens 160S and the sound got a lot more refined with even, believe it or not, reasonable bass. My oscillator has THD at output in the region of 0.1% mostly due to the step-up transformer, compared to 5-6% from the mains.
Another, probably better solution is to copy Linn's Valhalla. Not much worth copying as far as the oscillator is concerned, just the discrete high voltage amp in place of the step-up. I saw someone selling the circuit on ebay (?!) but i'll probably take it off the board whenever i get the time.
If you do make the oscillator the next worthwile step will be providing a second phase-shifted sine and getting rid of the capacitor. My AVR is happy to generate a second sine, only i've never really bothered building a second DAC/AMP/stepup to test it. Will probably do that once i have a Valhalla clone working
cheers
peter
Another, probably better solution is to copy Linn's Valhalla. Not much worth copying as far as the oscillator is concerned, just the discrete high voltage amp in place of the step-up. I saw someone selling the circuit on ebay (?!) but i'll probably take it off the board whenever i get the time.
If you do make the oscillator the next worthwile step will be providing a second phase-shifted sine and getting rid of the capacitor. My AVR is happy to generate a second sine, only i've never really bothered building a second DAC/AMP/stepup to test it. Will probably do that once i have a Valhalla clone working
cheers
peter
Wien
Could you send me the scheme you used? You don't change to 45rpm, do you?
As far I see the problem is the step-up stage. isn't it? Is a transformerso such a bad thing ?
The sonic advantages are so big, eh? well, then I'll forget about the pulley change and I'll follow the DIY path, and build an oscillator.
Besides, I'm thinking about the voltage applied to the motor. The torque follows a square law for the voltage (triple the voltage means 9 times torque) but I don't know the advantages of the torque ratio. I read somewhere that low torque is better, once the platter is in motion. The starting is not a problem since there is always a hand to help and not let the belt to suffer tracking loss. I will search in the DIY TT thread.
What are the advantages of getting rid of the cap? Maybe that adjusting the angle between signals can improve the vibration of the motor?
You have to tell me more about your TD160. The main bearing of mine is close to perfection. Is a nice tt, what do you think?
Could you send me the scheme you used? You don't change to 45rpm, do you?
As far I see the problem is the step-up stage. isn't it? Is a transformerso such a bad thing ?
The sonic advantages are so big, eh? well, then I'll forget about the pulley change and I'll follow the DIY path, and build an oscillator.
Besides, I'm thinking about the voltage applied to the motor. The torque follows a square law for the voltage (triple the voltage means 9 times torque) but I don't know the advantages of the torque ratio. I read somewhere that low torque is better, once the platter is in motion. The starting is not a problem since there is always a hand to help and not let the belt to suffer tracking loss. I will search in the DIY TT thread.
What are the advantages of getting rid of the cap? Maybe that adjusting the angle between signals can improve the vibration of the motor?
You have to tell me more about your TD160. The main bearing of mine is close to perfection. Is a nice tt, what do you think?
Raka said:
Um, try Thorens web site, www.thorens.ch and see if there's a distributor near you.
Cheers, Keith
Raka
The building blocks of the DIY PS are very simple, so i've never drawn a circuit. The Wien bridge is described in most electronics textbooks, like 'The Art of Electronics'. Use a simple RC filter set to around 100-150Hz at output and your choice of power amp. Initially i used a Rotel, then an LM3886 and an STK. My case is more demanding as the Garrard 301 takes full 16W.
Spinning at lower than nominal voltage probably reduces vibration as it certainly improves the sound. There is however an optimum voltage which you can determine by listening.
The TD 160 is not my favourite Thorens and that's why i sold mine. It is a nice turntable but i seem to prefer 124 and 125 by a large margin. I also prefer the Linn and the old Garrards (301/401). Yes, i have them all.
cheers
peter
The building blocks of the DIY PS are very simple, so i've never drawn a circuit. The Wien bridge is described in most electronics textbooks, like 'The Art of Electronics'. Use a simple RC filter set to around 100-150Hz at output and your choice of power amp. Initially i used a Rotel, then an LM3886 and an STK. My case is more demanding as the Garrard 301 takes full 16W.
Spinning at lower than nominal voltage probably reduces vibration as it certainly improves the sound. There is however an optimum voltage which you can determine by listening.
The TD 160 is not my favourite Thorens and that's why i sold mine. It is a nice turntable but i seem to prefer 124 and 125 by a large margin. I also prefer the Linn and the old Garrards (301/401). Yes, i have them all.
cheers
peter
Thanks for posting the link Bret. I was trying to remember where i've seen this. It will do with minor mods. Replace the 741 with a 5534 or anything respectable if you really want low distortion. Place a capacitor between the oscillator o/p and the LM3886 i/p in order to eliminate DC. It's now not essential to use the electrolytics at the o/p, just connect the step-up directly to 3886. I also see absolutely no point in the 1ohm/10W resistors in the PS, it will work fine without them (actually better).
As with any Wien bridge osc, care and attention are required to obtain stable and undistorted o/p. Some means of measuring distortion will be invaluable.
cheers
peter
As with any Wien bridge osc, care and attention are required to obtain stable and undistorted o/p. Some means of measuring distortion will be invaluable.
cheers
peter
50/60Hz Wien bridges (and Garrard 301's)
Although you can make a 50/60Hz Wien bridge, it can be difficult to keep the distortion down because of thermal cycling of the thermistor/lamp. In this instance, a lamp is likely to be better than the traditional R53 bead thermistor. Another possibility is the state variable oscillator described in Ian Hickman's "Analog Electronics."
A Garrard 301 doesn't have to consume 16W even though the chassis plate specifies 14VA. I assume that you have disabled the eddy current brake? If you resonate the motor by placing a 1.84uF (50Hz) 1.29uF (60Hz) capacitor in series (240V settings), you obtain a nice resistive load. If you drop the voltage to 108V across the motor terminals (reduces vibration), the measured power dissipation in the motor is only 4W. Under these conditions, I thought that quiet bits were slightly quieter and record noise was reduced.
Although you can make a 50/60Hz Wien bridge, it can be difficult to keep the distortion down because of thermal cycling of the thermistor/lamp. In this instance, a lamp is likely to be better than the traditional R53 bead thermistor. Another possibility is the state variable oscillator described in Ian Hickman's "Analog Electronics."
A Garrard 301 doesn't have to consume 16W even though the chassis plate specifies 14VA. I assume that you have disabled the eddy current brake? If you resonate the motor by placing a 1.84uF (50Hz) 1.29uF (60Hz) capacitor in series (240V settings), you obtain a nice resistive load. If you drop the voltage to 108V across the motor terminals (reduces vibration), the measured power dissipation in the motor is only 4W. Under these conditions, I thought that quiet bits were slightly quieter and record noise was reduced.
Hi,
Although I know nothing about vinyl:
Several years ago I used to supply a "maker" with a 50 / 60 Hz 25 watt power supply for the 301 & 401.
The circuit had 2 parts:
1) A crystal osc, a 50 /60 Hz switchable divider and a Butterworth filter to produce quite a clean sine wave at the reference frequency.
2) A Bridge Tied Load VFET amp, producing 120V per side, antiphase.
The reference osc uses a standard 15VA 2 secondary transformer, and is properly mains isolated.
The BTL circuit was not mains isolated and depended on being mounted in a well insulated and earthed box, and all tests being carried out in an earth free and isolated environment.
I cannot recommend the BTL amp for home construction, but I have no hesitation in recommending the reference oscillator circuit.
I have just 6 PCB's left, which I'm prepared to pass on gratis in the UK, or at US$1, or 1Euro, to cover postage cost elsewhere.
I'll supply the reference circuit, but not the BTL circuit. I suggest that for home construction, a transformer is more appropriate.
It's up to you to work out the power amp bit, but it's only like audio.
The PCB's are double sided copper PTH, with legend. They measure 100mm x 120mm.
E-mail me if you want one. I'll work on the basis of 1 for each request until the're gone.
Please only ask for one if you're sure you'll use it
Cheers,
Although I know nothing about vinyl:
Several years ago I used to supply a "maker" with a 50 / 60 Hz 25 watt power supply for the 301 & 401.
The circuit had 2 parts:
1) A crystal osc, a 50 /60 Hz switchable divider and a Butterworth filter to produce quite a clean sine wave at the reference frequency.
2) A Bridge Tied Load VFET amp, producing 120V per side, antiphase.
The reference osc uses a standard 15VA 2 secondary transformer, and is properly mains isolated.
The BTL circuit was not mains isolated and depended on being mounted in a well insulated and earthed box, and all tests being carried out in an earth free and isolated environment.
I cannot recommend the BTL amp for home construction, but I have no hesitation in recommending the reference oscillator circuit.
I have just 6 PCB's left, which I'm prepared to pass on gratis in the UK, or at US$1, or 1Euro, to cover postage cost elsewhere.
I'll supply the reference circuit, but not the BTL circuit. I suggest that for home construction, a transformer is more appropriate.
It's up to you to work out the power amp bit, but it's only like audio.
The PCB's are double sided copper PTH, with legend. They measure 100mm x 120mm.
E-mail me if you want one. I'll work on the basis of 1 for each request until the're gone.
Please only ask for one if you're sure you'll use it
Cheers,
Attachments
Here's the schematic of the reference oscillator:
http://www.dhaen.org.uk/vdocs/PHsch_ref.gif
Cheers,
http://www.dhaen.org.uk/vdocs/PHsch_ref.gif
Cheers,
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