I think both Thorens and Garrard were counting pennies. Despite the genius belt system TD124 doesn't have better than average rumble figures. The metal on the Garrard motors is more to do with vibration damping rather than magnetic field. Doubtless the cast iron of 401 is a good magnetic shield. 401 should be outstandingly better than 301. Overal it isn't. 501 takes the best of both 301 and 401. The 501 motor has more metal in the motor which gives a better magnetic field. The motor in itself has less harmonic distortion. The TD124 motor has least metal. As simplistic as that is it is how it works. The two companies were very experianced in these things.
Without wishing to upset people I would say the TD124 belt is both it's strong point and it's weak point. For 90% of users the belt filters harmonics of motor or mains. If the motor is made quieter using a regenerator the belt stops some of that being heard. The same PSU on a Garrard 301 is night and day. More matertape than turntable sound.
The two magnetic speed adjusers on TD124/301/401 do more good than harm. They as Mr Verdier pointed out make for a liquid like resistance that dominates stylus forces ( 10 : 1 ? ). The graph is like a liquid except in slope. A PSU allows fine tuning. You could even program in a warm up phase. Aim for no quantity being > 0.1% in the voltage domain ( normal measurements like amplifiers ). You most likely will need complex feedback as in my example which can go badly wrong. Without feedback -48 dB would be reasonable which is 8 dB better than m,ains electricity could ever be. I am told the USA can be - 20 dB.
This is the noise on my mains. I live very near the the large and local substations. The transformers are of very high quality from a long time ago. I have nothing of note under 250 Hz. - 37 dB is just over 1 %. For me a PSU is marginal. As they saay, don't try this at home.
This is my new home. My Woodstock home had the more typical flat top wave. Don't swallow all that is said about that. It's most how voltage is regulated. That's a long story, trust me when I say mostly it's misunderstood.
Without wishing to upset people I would say the TD124 belt is both it's strong point and it's weak point. For 90% of users the belt filters harmonics of motor or mains. If the motor is made quieter using a regenerator the belt stops some of that being heard. The same PSU on a Garrard 301 is night and day. More matertape than turntable sound.
The two magnetic speed adjusers on TD124/301/401 do more good than harm. They as Mr Verdier pointed out make for a liquid like resistance that dominates stylus forces ( 10 : 1 ? ). The graph is like a liquid except in slope. A PSU allows fine tuning. You could even program in a warm up phase. Aim for no quantity being > 0.1% in the voltage domain ( normal measurements like amplifiers ). You most likely will need complex feedback as in my example which can go badly wrong. Without feedback -48 dB would be reasonable which is 8 dB better than m,ains electricity could ever be. I am told the USA can be - 20 dB.
This is the noise on my mains. I live very near the the large and local substations. The transformers are of very high quality from a long time ago. I have nothing of note under 250 Hz. - 37 dB is just over 1 %. For me a PSU is marginal. As they saay, don't try this at home.
This is my new home. My Woodstock home had the more typical flat top wave. Don't swallow all that is said about that. It's most how voltage is regulated. That's a long story, trust me when I say mostly it's misunderstood.
This is a similar test using a low cost Velleman scope. Compare with the previous. 10 dB per block vertical. It shows mains distortion at my house. It also shows that a so called low THD inverter would be no better and likely worse. This Velleman scope whilst being of very limited bandwidth is every bit as good as the expensive scope in that range. The range is 10 times better than we might need. Being USB is no bad thing.
https://cpc.farnell.com/velleman-instruments/pcsu01/pc-scope/dp/IN07777
https://cpc.farnell.com/multicomp/m...st=50va 2 output chassis mounting transformer
The results are close to the expensive scope and safer for the user and computer. Velleman have a free demo version. It adopts the real device if you buy it. The demo is very like what you might use.
https://cpc.farnell.com/velleman-instruments/pcsu01/pc-scope/dp/IN07777
https://cpc.farnell.com/multicomp/m...st=50va 2 output chassis mounting transformer
The results are close to the expensive scope and safer for the user and computer. Velleman have a free demo version. It adopts the real device if you buy it. The demo is very like what you might use.
To sum up.
If your bearings are OK ( and 90% are ) give them some oil. 3 in 1 SAE20 motor oil seems OK. A new belt of original quality is important. Old bearings are often better than replacements. Worn bearings often tick. Alas bad mains electricity makes a similar noise.
The only big deal up grade is a pure sine wave PSU of better than 0.1% THD if possible. 1% if mostly second harmonic would be OK.
Due to the belt mostly this will be an ear near motor upgrade. For a Garrard 301 it's a more obvious upgrade. Jazz sounds more real.
The low cost Velleman oscilloscope is fine for PSU design work if an isolation transformer is used. I will help anyone who gets that far. In the 501 project a world record for idler rumble was set. I now know that the low cost Velleman scope would be good enough to design 501. Believe it or not you now know how in many details.
The metal I refer to is motor steel. M6 alloy might well be better on a TD124. An inductor I had made went from 3 mH to 13 mH using M6. I would expect the motor to have more torque in M6. It might need a lower voltage. It should have a lower self THD. Apart from being a bit mean on metal the TD124 motor is an ideal design. Having worked on a few I never really saw a way of simply upgrading them. The 501 finds it's exact magnetic centre. If you space off the TD124 bottom bearing by 2 mm and switch on see if it centres where it is forced to. It needs to be on it's side to do this. I bet it won't centre in it's old position. It has more torque when correct. This is not unlike how a linear AC locomotive motor works for monorails. It also self centres.
The TD124 as designed is a perfect workhorse. The belt is both good and bad. I often thought of 15 Vrms windings ( 2 x 8 Vrms in bridge ). Worth a thought.
If your bearings are OK ( and 90% are ) give them some oil. 3 in 1 SAE20 motor oil seems OK. A new belt of original quality is important. Old bearings are often better than replacements. Worn bearings often tick. Alas bad mains electricity makes a similar noise.
The only big deal up grade is a pure sine wave PSU of better than 0.1% THD if possible. 1% if mostly second harmonic would be OK.
Due to the belt mostly this will be an ear near motor upgrade. For a Garrard 301 it's a more obvious upgrade. Jazz sounds more real.
The low cost Velleman oscilloscope is fine for PSU design work if an isolation transformer is used. I will help anyone who gets that far. In the 501 project a world record for idler rumble was set. I now know that the low cost Velleman scope would be good enough to design 501. Believe it or not you now know how in many details.
The metal I refer to is motor steel. M6 alloy might well be better on a TD124. An inductor I had made went from 3 mH to 13 mH using M6. I would expect the motor to have more torque in M6. It might need a lower voltage. It should have a lower self THD. Apart from being a bit mean on metal the TD124 motor is an ideal design. Having worked on a few I never really saw a way of simply upgrading them. The 501 finds it's exact magnetic centre. If you space off the TD124 bottom bearing by 2 mm and switch on see if it centres where it is forced to. It needs to be on it's side to do this. I bet it won't centre in it's old position. It has more torque when correct. This is not unlike how a linear AC locomotive motor works for monorails. It also self centres.
The TD124 as designed is a perfect workhorse. The belt is both good and bad. I often thought of 15 Vrms windings ( 2 x 8 Vrms in bridge ). Worth a thought.
Thanks for all this input Nigel. It helps to get some insight from an industry professional.
When considering the Thorens belt/idler layout I have come to regard it as a compromise and not any sort of genius idea. On the one hand motor vibes are filtered by the belt and don't reach as much into the idler wheel/platter. And the eddy brake betwixt the stepped idler and motor pulley does indeed serve to smooth the flow of power going in.
On the other hand, however it is the architecture of this belt/idler design that leads to a second intrusion of vibrations going into the chassis. But not just any place on the chassis. The obvious fly in the design is the proximity of the stepped pulley/idler wheel to the armboard.
When listening to an operating TD124 with a newly bought stethoscope in order to understand how drive train vibrations migrate throughout the chassis it became readily appearant that vibrations are as strong at the armboard as they are near the motor mounting. Perhaps even a bit stronger. This has been discussed on this thread before so I am just repeating old news here. Every sample TD124 I've had over here did exhibit vibrations at the armboard. I imagine its designer knew this from before they had a working prototype, but considered it acceptible.
I suppose this long thread has gone on long enough to lose interest for its original poster. And it truly is a long thread chock full of very useful information to those wanting to understand theiry newly bought but old and in need of refurbishment TD124 players. All they have to do is read the thing through and mark the places where the info applies to them.
-Steve
100%.
Some slightly odd choices slightly ruined it. 301 is more fun than TD124/401. It is strictly speaking slighly below a hi fi standard. So is the typical LP. The 301 has verve. 501 is is a high end performer which retains the verve. It would need a book to explain that. I sketched the 501 motor and sent it by Fax! I think Terry still has it! 1990 or slightly before. The rest was finding the money to do it and eat. 501 is based on a Colchester lathe. Would you believe SME couldn't go that large ( they made the 501 bearing ). The platter as you can see is a modern lathe. None of the F1 boys could or would do it. Body scanners uses things that large. Oxford is famous for that. I have built the big coils for them. My old boss my contact. All harder than you would think. I am not a mechanical engineer. I took to it like a duck to water. I find mechanical engineers more my type of people.
Just as the 501 is an improved 301 a better TD124 possible. Reducing the motor vibration using a low distortion PSU is the easier route.
My TD124 is or was the photo in the back of Hi Fi World. It came from Sunshine Records Jericho Oxford. I bought my ECM jazz LP's there. The rightly famous Michael Gerzon lived nearby and was a friend ( lossless digital compression and microphones ). I seem to remember he had a TD124. Percy Wilson also lived in nearby Plantation Road ( 401 or SP10 my guess ). He invented many LP things. 119 mm 63.5 mm zero points were his and the Loricraft PCR ( my baby ) now SME. The best PRC science was from the Mormon Church ! They did microscope tests.
Some slightly odd choices slightly ruined it. 301 is more fun than TD124/401. It is strictly speaking slighly below a hi fi standard. So is the typical LP. The 301 has verve. 501 is is a high end performer which retains the verve. It would need a book to explain that. I sketched the 501 motor and sent it by Fax! I think Terry still has it! 1990 or slightly before. The rest was finding the money to do it and eat. 501 is based on a Colchester lathe. Would you believe SME couldn't go that large ( they made the 501 bearing ). The platter as you can see is a modern lathe. None of the F1 boys could or would do it. Body scanners uses things that large. Oxford is famous for that. I have built the big coils for them. My old boss my contact. All harder than you would think. I am not a mechanical engineer. I took to it like a duck to water. I find mechanical engineers more my type of people.
Just as the 501 is an improved 301 a better TD124 possible. Reducing the motor vibration using a low distortion PSU is the easier route.
My TD124 is or was the photo in the back of Hi Fi World. It came from Sunshine Records Jericho Oxford. I bought my ECM jazz LP's there. The rightly famous Michael Gerzon lived nearby and was a friend ( lossless digital compression and microphones ). I seem to remember he had a TD124. Percy Wilson also lived in nearby Plantation Road ( 401 or SP10 my guess ). He invented many LP things. 119 mm 63.5 mm zero points were his and the Loricraft PCR ( my baby ) now SME. The best PRC science was from the Mormon Church ! They did microscope tests.
I said that the TD124 belt cum idler is a genius design. It is, but is nothing like as good as it should be.
The Rolls Royce Merlin was the other way. The German engineers thought that the Merlin looked wrong. RR used many little engineering tricks to get reliable power. To Germany eyes the crank pins were too small. The Germans realised RR thought differently. In 1943 it was too late to unlearn.
The Rolls Royce Merlin was the other way. The German engineers thought that the Merlin looked wrong. RR used many little engineering tricks to get reliable power. To Germany eyes the crank pins were too small. The Germans realised RR thought differently. In 1943 it was too late to unlearn.
After a long time of not having followed this thread here are some measurements to show that it is not a luxury to replace the bearings of the E50 motor.
First a E 50 motor current spectrum with rotational sidebands of a cleaned and re-oiled motor with original sinterbushings , measured diameter 4.767 mm .
and flutter figure from the motor itself.
Second a revised motor with new sinterbushings 4.750 mm and the flutter
measurement.
Results speak for themselfs,
First a E 50 motor current spectrum with rotational sidebands of a cleaned and re-oiled motor with original sinterbushings , measured diameter 4.767 mm .
and flutter figure from the motor itself.
Second a revised motor with new sinterbushings 4.750 mm and the flutter
measurement.
Results speak for themselfs,
Attachments
A word of warning about new bearings. Check the motor shaft end where it meets the ball bearing. If there is a noticable dent it might be wise to stick with what you have. At Loricraft we never really found an easy fix for that. A SAE 30 oil could help. Grinding and re-hardning wasn't 100% sucessful. The TD124 belt helps reduce the noise it makes. A Garrard 301 is in big trouble if this happens. Always assume the Thorens motor can be made to work as is. 90% can be made to work very well. Mine couldn't. I completely messed up some 501 motor bearings ( about 10 sets ). I learnt a lot from that. I was rushing the work to go home. What usually was OK, wasn't. The next bearings we made improved due to it. All were perfect when built up as the 501 is very critical on this, if wrong it is very obvious. I don't doubt TD124 motor bearings can be improved.
If you have a new spindle made you might not centre it well enough to retain balance. Likely it can be pushed out. Having never done this to a TD124 I could not say.
If you have a new spindle made you might not centre it well enough to retain balance. Likely it can be pushed out. Having never done this to a TD124 I could not say.
Question for you all,
I lubricated my stepped pulley (MKI with the first step pulley design), with 3-4 drops into the well.
Now my stepped pulley is running way too fast, and the strobe speed is not steady.
My motor has a 30 second spin down time and 1760 RPM, and gets up to speed in 1/2 Revolution. It has the MKI coils.
Any thoughts on how to correct my overlubrication, and what's causing the speed drift here?
I put on a fresh belt but it didn't make a difference.
I lubricated my stepped pulley (MKI with the first step pulley design), with 3-4 drops into the well.
Now my stepped pulley is running way too fast, and the strobe speed is not steady.
My motor has a 30 second spin down time and 1760 RPM, and gets up to speed in 1/2 Revolution. It has the MKI coils.
Any thoughts on how to correct my overlubrication, and what's causing the speed drift here?
I put on a fresh belt but it didn't make a difference.
Steve will probably have a pretty good idea of what's going on here.
I'm thinking the bearing is worn and when you lubricated it the internal sludge got washed out of the bearing, and it's now loose and wobbly. (Would account for the fast and erratic behavior. )The other possibility with that oil has gotten somewhere it should not have like on the idler pulley and running surfaces of the intermediate pulley.
Has the eddy current brake been adjusted or disturbed recently?
I'm thinking the bearing is worn and when you lubricated it the internal sludge got washed out of the bearing, and it's now loose and wobbly. (Would account for the fast and erratic behavior. )The other possibility with that oil has gotten somewhere it should not have like on the idler pulley and running surfaces of the intermediate pulley.
Has the eddy current brake been adjusted or disturbed recently?
Kevin,
Thx for the reply. The Eddy current hasn't been adjusted or disturbed.
The TT will start fast, then slow down to stabilizing, then run a bit slow, even though I can make it run fast.
Yet, the motor shows 1760 RPM and that long spin down time, so I don't think it is the motor. I checked that RPM with the belt off after and hour of runtime and it held constant as well.
I want to get the coils (to audiosilente) and switch (to a microswitch) changed anyway so perhaps I will take it to Greg Metz and have him look at it...
Thx for the reply. The Eddy current hasn't been adjusted or disturbed.
The TT will start fast, then slow down to stabilizing, then run a bit slow, even though I can make it run fast.
Yet, the motor shows 1760 RPM and that long spin down time, so I don't think it is the motor. I checked that RPM with the belt off after and hour of runtime and it held constant as well.
I want to get the coils (to audiosilente) and switch (to a microswitch) changed anyway so perhaps I will take it to Greg Metz and have him look at it...
You should not use grease in the oilite bushing in the top of your step pulley - if it is sloppy you should replace the bushing or get someone to do it for you. (Use 20 weight electric motor oil or similar) Audiosilente (Simone Luchetti) made an excellent replacement, but I am not sure you can get it currently.
They offer a replacement step pulley for the MKI if there is no alternative.
New Stepped Pulley for Thorens 124 Mk1 Made in Italy by Audiosilente 7426765971691 | eBay
You can contact Simone directly from his site, note that his online store is not currently open to the public, but he has stuff on eBay.
idler wheel thorens td124 (contact email addresses are on this page)
If you have a strong magnet and moving it closer to the pulley has no effect either the magnet is not as strong as you think, it's actually too far away or the internal shutter is not moving when you turn the speed control knob.
How about some pictures?
They offer a replacement step pulley for the MKI if there is no alternative.
New Stepped Pulley for Thorens 124 Mk1 Made in Italy by Audiosilente 7426765971691 | eBay
You can contact Simone directly from his site, note that his online store is not currently open to the public, but he has stuff on eBay.
idler wheel thorens td124 (contact email addresses are on this page)
If you have a strong magnet and moving it closer to the pulley has no effect either the magnet is not as strong as you think, it's actually too far away or the internal shutter is not moving when you turn the speed control knob.
How about some pictures?
Kevin,
Thx for the reply and advice/your time, I appreciate it. I asked Simone and he suggested moving the Eddy Brake closer as well, so I will try that again.
Listening to records today, what is actually happening is my 124 starts fast, and then slows down over the next several sides, to proper speed, so I can achieve the speed, it's not that it's running too fast all the time. Running fast is never audible though, only seen by the strobe.
I also tested for play in my bearing, and there is no play pushing down on the pulley. Given the motor has been revised, perhaps this is just normal warm up fluctuation
Thx for the reply and advice/your time, I appreciate it. I asked Simone and he suggested moving the Eddy Brake closer as well, so I will try that again.
Listening to records today, what is actually happening is my 124 starts fast, and then slows down over the next several sides, to proper speed, so I can achieve the speed, it's not that it's running too fast all the time. Running fast is never audible though, only seen by the strobe.
I also tested for play in my bearing, and there is no play pushing down on the pulley. Given the motor has been revised, perhaps this is just normal warm up fluctuation
Additionally, my strobe has not been stabilizing, it will gradually run slightly slow.
One thing I noticed with the platter off tonight:
It looks like the belt is wobbly (on the portion as it heads toward the step pulley, away from the motor pulley), when I try to clean the motor pulley the belt falls off the pulley.
I hope I don't have a bent motor spindle, based on that belt wobbling. I do think I should have a specialist look at it
One thing I noticed with the platter off tonight:
It looks like the belt is wobbly (on the portion as it heads toward the step pulley, away from the motor pulley), when I try to clean the motor pulley the belt falls off the pulley.
I hope I don't have a bent motor spindle, based on that belt wobbling. I do think I should have a specialist look at it
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Did you replace the belt? Hanze HiFi has belts that work well, many others don't. I had a lot of problems with belts.
Also what about the motor mounting bushings? Replaced and with what?
The belt oscillating up and down on the step pulley is a possible indication that the oilite bearing (earlier 124 prior to 2 bearing design in chassis) is worn out and needs to be replaced. Contact Simone at AudioSilente and see if he has any.
Remove belt before cleaning the pulley surfaces. The belt should not be handled with oily fingers. If you can get talc powder this helps a lot with the belt sticking as it leaves the stepped pulley.
What did you use to lubricate the motor? I had similar problems with it running fast when cold and slower when warmed up and it was the lubricants used were a bit too light.
It is all a bit of a juggling act. I have mostly given up on tinkering with mine, I just let them do their own thing - the one with 3 phase drive is not finicky, the 124 MKII needs a full 30 minutes to get fully up to speed in cold weather so I don't use it much. Eventually I will take it apart and try to figure out the problem. I will probably get new motor coils because I have always had more trouble with speed stability and warm up with MKII motors than with any of the earlier motors. (There are at least 2 earlier revisions)
Also what about the motor mounting bushings? Replaced and with what?
The belt oscillating up and down on the step pulley is a possible indication that the oilite bearing (earlier 124 prior to 2 bearing design in chassis) is worn out and needs to be replaced. Contact Simone at AudioSilente and see if he has any.
Remove belt before cleaning the pulley surfaces. The belt should not be handled with oily fingers. If you can get talc powder this helps a lot with the belt sticking as it leaves the stepped pulley.
What did you use to lubricate the motor? I had similar problems with it running fast when cold and slower when warmed up and it was the lubricants used were a bit too light.
It is all a bit of a juggling act. I have mostly given up on tinkering with mine, I just let them do their own thing - the one with 3 phase drive is not finicky, the 124 MKII needs a full 30 minutes to get fully up to speed in cold weather so I don't use it much. Eventually I will take it apart and try to figure out the problem. I will probably get new motor coils because I have always had more trouble with speed stability and warm up with MKII motors than with any of the earlier motors. (There are at least 2 earlier revisions)
I am using the Schopper Belt, and their oil. I'm thinking this is due to belt slippage of some kind, perhaps I should try a Hanze belt instead. (The motor was done by Schopper several years ago).
I just find it interesting the belt is wobbling only on the portion going away from the motor pulley, but towards the step pulley.
Kevin, thanks for your suggestions, I appreciate your time and advice.
I just find it interesting the belt is wobbling only on the portion going away from the motor pulley, but towards the step pulley.
Kevin, thanks for your suggestions, I appreciate your time and advice.
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Ah, that does sound familiar. Definitely try the Hanze HiFi belt, and inspect and clean the motor pulley carefully. Talc helps but is a temporary fix IMLE.
The belt material, thickness, and tension all play a role in the issue you describe. I have some original OEM belts which generally behave better than modern replacements with a few exceptions.
The belt material, thickness, and tension all play a role in the issue you describe. I have some original OEM belts which generally behave better than modern replacements with a few exceptions.