Hi, From my understanding, closed loop looks better on paper. But the correction of speed happens fractionally after the function is needed. Which we can perceive & some people perceive it as tiring or hard.
Open circuit's on T/T require a massive platter to enable the smoothing out of motor variation, but you cannot hear this in the listening position. My Mylar belt drive & SP15 when listening I cannot tell which is which in a blind test.
Again all 3 have speed stability in the 0.05 to 0.07 range. When the stability gets of over 0.11 is when I can hear speed variation.
cheers
Open circuit's on T/T require a massive platter to enable the smoothing out of motor variation, but you cannot hear this in the listening position. My Mylar belt drive & SP15 when listening I cannot tell which is which in a blind test.
Again all 3 have speed stability in the 0.05 to 0.07 range. When the stability gets of over 0.11 is when I can hear speed variation.
cheers
Good questions, Panos.
Yes, the Chinese DC Bench Supply had both course and fine adjustments, but I could not achieve 33.33RPM. I should also mention that although the speed stability was high, the music did not sound as good as our OL Advance DC Speed Controller.
SPEED-DRIFT:
Platter speed changes. That is to say that the platter speed after playing an LP for some time, is different from the starting speed.
Typically, on our LP12, this speed-drift takes the form of acceleration.
Whilst very occasionally we might enjoy a complete LP side without speed-drift - and it sounds superb - invariably the platter speed will change within the time it takes to play one LP side.
Often - if we are focused on the music - this platter speed change will be easily heard as a change in pitch, most readily apparent on sustained piano notes and massed string chords.
Personally, I've never considered that I am unusually sensitive to pitch change - as to me, it is patently obvious when pitch changes mid-song - but I suppose it is possible that it is my own sensibility.
Nevertheless, a quick check with the strobe confirms that I am NOT imagining it.
For what it is worth, I would normally strobe check platter-speed with the stylus in the groove.
Occasionally - when I am conducting multiple speed tests - I will strobe check the platter speed without the stylus in the groove, for convenience. In testing for speed stability, I don't think it matters too much, as long as I am consistent in this method - at start and end.
Frankly, I am more concerned with getting speed "stability" [no speed variation] than speed "accuracy" [speed exactly 33.333 RPM] - but achieving both would be ideal.
As for the OL trim pots, my original OL PCB was replaced in September 2018, with a MK12 PCB. So, my trim pots are less than five years old. I don't think they are the problem, as to my knowledge, most pots - even old ones - don't drift in value, while static. Happy to be corrected on this.
Meanwhile...
I have been testing our wall outlet iFi iPower AC-DC 9V transformer - that feeds our OL Advanced DC Motor Speed Controller.
This little iFi iPower unit delivered a healthy improvement to sound quality, when we first installed it around 10-years ago - presumably by lowering "noise" reaching the DC motor.
The iFi iPower is supposed to remove noise AND stabilise voltage. My testing shows that it is delivering 9.13V / 9.14V / 9.15V and wandering around following the AC-Mains fluctuations - so it seems to be a lot better at removing noise, than stabilising voltage supply.
I am wondering if this voltage variation is NOT being managed well by the (seemingly) fairly basic OL Advanced DC Motor Speed Controller circuit - and is the possible cause of our speed-drift issues.
On this basis, I have ordered a new 25W AC-DC 9V Linear Power Transformer, to feed 9V (solid) to the OL Advanced DC Motor Speed Controller, to see if this can remedy the problem - or at least help.
It should arrive in a day or two and I will have a 7-day right-of-return, if it does not solve the problem.
Let's see...
As an interesting aside, whilst OL recommends a DC 9V supply for the DC-100 motor we are running, this new 25W Linear Power Supply ALSO offers the ability to adjust voltage - right up to 20V. So, I may be able to have a play with this too, adding a few more volts to see if our DC motor performance improves.
(I'll NOT be trying the maximum 20V supply to OL Advanced DC Motor Speed Controller, obviously...)
I have been testing our wall outlet iFi iPower AC-DC 9V transformer - that feeds our OL Advanced DC Motor Speed Controller.
This little iFi iPower unit delivered a healthy improvement to sound quality, when we first installed it around 10-years ago - presumably by lowering "noise" reaching the DC motor.
The iFi iPower is supposed to remove noise AND stabilise voltage. My testing shows that it is delivering 9.13V / 9.14V / 9.15V and wandering around following the AC-Mains fluctuations - so it seems to be a lot better at removing noise, than stabilising voltage supply.
I am wondering if this voltage variation is NOT being managed well by the (seemingly) fairly basic OL Advanced DC Motor Speed Controller circuit - and is the possible cause of our speed-drift issues.
On this basis, I have ordered a new 25W AC-DC 9V Linear Power Transformer, to feed 9V (solid) to the OL Advanced DC Motor Speed Controller, to see if this can remedy the problem - or at least help.
It should arrive in a day or two and I will have a 7-day right-of-return, if it does not solve the problem.
Let's see...
As an interesting aside, whilst OL recommends a DC 9V supply for the DC-100 motor we are running, this new 25W Linear Power Supply ALSO offers the ability to adjust voltage - right up to 20V. So, I may be able to have a play with this too, adding a few more volts to see if our DC motor performance improves.
(I'll NOT be trying the maximum 20V supply to OL Advanced DC Motor Speed Controller, obviously...)
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A decent bench power supply has near zero output resistance.
A properly designed motor controller can have negative output resistance to give some motor load compensation
A properly designed motor controller can have negative output resistance to give some motor load compensation
Panos,
I think David is saying that a decent Bench Power Supply is not necessarily designed with the required output resistance to correctly control the speed of a specific DC motor.
I’m guessing that each different DC motor probably has its own unique requirements, in this regard.
I think David is saying that a decent Bench Power Supply is not necessarily designed with the required output resistance to correctly control the speed of a specific DC motor.
I’m guessing that each different DC motor probably has its own unique requirements, in this regard.
I tried feeding my OL Advanced controller from a range of different DC voltages. I found that the sound quality was best when it was fed with 24v. When using 9v the sound became very soft with the dynamics of a wet noodle and speed stability became rather vague. The OL outbound power supplies are just a transformer in a box. The transformers are 15v which results in around 24v DC after rectification. The supply that I am currently using is a 24v linear supply using a 120VA torroid and 24 x 2200μf Vishay capacitors bypassed with a 100nf polycap. There is also a bit of mains filtering built in as my mains supply isn't the best. This supply sounds notably better than OLs Top ~£400 offering.
Going from the Advanced controller with OLs supply and DC200 motor to my current setup of the Ultra controller with my DIY power supply and Maxon 226764 motor has been a massive upgrade.
I'd say that 75% of the improvement is due to the motor, 15% the power supply and 10% the controller.
I have tried the Advanced controller against a couple of others makes and it has comfortable beaten them all but only when using a better supply, either OLs upgrade or my own. The OLs performance is VERY dependant on the quality of the power you feed it.
A friend of mine is in the process of upgrading his deck with the Linn Radikal. When he has I will be making an adapter lead so that I can run the Radikal's motor from my OL controller and supply. It will be interesting to see how the OL compares to something that costs over 5 times as much.
Niffy
Going from the Advanced controller with OLs supply and DC200 motor to my current setup of the Ultra controller with my DIY power supply and Maxon 226764 motor has been a massive upgrade.
I'd say that 75% of the improvement is due to the motor, 15% the power supply and 10% the controller.
I have tried the Advanced controller against a couple of others makes and it has comfortable beaten them all but only when using a better supply, either OLs upgrade or my own. The OLs performance is VERY dependant on the quality of the power you feed it.
A friend of mine is in the process of upgrading his deck with the Linn Radikal. When he has I will be making an adapter lead so that I can run the Radikal's motor from my OL controller and supply. It will be interesting to see how the OL compares to something that costs over 5 times as much.
Niffy
After considering specs, customer feedback, etc, I have finally taken the decision and just ordered a Maxon RE-max 226764 motor (with precious metal brushes, sintered sleeve bearings and CLL. Model: RE-max29 EBCLL 15W SL 1WE), which is actually the same one Niffy uses and is obviously so happy with. I've decided to pass on the DCX22L, because of some comments about the bearings failing prematurely.
As a matter of fact, I've received similar, very positive feedback from another friend, Boris (planet IX), about the RE-max motor. Boris was also kind enough to help me build a negative impedance controller, which I am going to test (when ready) instead of the Origin Live Advanced controller.
So, now I will be waiting for a new motor and a new controller.
In the meantime, I've taken some wow & flutter measurements, which i will repeat after I've changed the motor and/or the controller. Curious to see whether I will see any changes in the measurements or whether wow & flutter is primarily affected by the platter and the bearing...
Panos
As a matter of fact, I've received similar, very positive feedback from another friend, Boris (planet IX), about the RE-max motor. Boris was also kind enough to help me build a negative impedance controller, which I am going to test (when ready) instead of the Origin Live Advanced controller.
So, now I will be waiting for a new motor and a new controller.
In the meantime, I've taken some wow & flutter measurements, which i will repeat after I've changed the motor and/or the controller. Curious to see whether I will see any changes in the measurements or whether wow & flutter is primarily affected by the platter and the bearing...
Panos
Congrats Panos!
It will be super-interesting to see how your new MAXON RE-max 226764 DC motor goes - and whether your homebake speed controller can better the OL Advanced.
I'll be waiting in the wings, reading with interest, to help determine my own next move.
Exciting times!
😊
It will be super-interesting to see how your new MAXON RE-max 226764 DC motor goes - and whether your homebake speed controller can better the OL Advanced.
I'll be waiting in the wings, reading with interest, to help determine my own next move.
Exciting times!
😊
Thanks for the great intel, Niffy.
Loads of great info you have shared here and you have now convinced me to at least try the 20V (max) feed on my inbound DC Power Supply, just to see if it offers some improvement to the OL Advanced DC Motor Speed Controller performance.
If the results are positive, I might spring for a bigger (again) Linear Power Supply. Let's see.
The OL / RADIKAL controller shootout will be absolutely compulsive reading.
Unmissable!
I am really interested myself, Sondeknz. As a matter of fact, I will start changing each link of the chain, one by one. First the motor, then the controller and then the power supply. Initially I was reluctant to go for a motor with a high nominal voltage (i.e. higher than 12V), but it seems that my fears may have been unjustified.
I am as curious as you are about the results!
😉
Yeah, I'm with you, Panos.
Step-by-step is the only way to really understanding what's cooking.
I'm hoping my own version of the OL Advanced DC Motor Speed Controller has the ability to manage the higher voltage - without overloading any PCB components.
That said, we are only talking fairly low DC voltage - even at DC 20V.
The good news is that the OL PCB is populated with through-hole components, so any repairs would be a doddle.
Step-by-step is the only way to really understanding what's cooking.
I'm hoping my own version of the OL Advanced DC Motor Speed Controller has the ability to manage the higher voltage - without overloading any PCB components.
That said, we are only talking fairly low DC voltage - even at DC 20V.
The good news is that the OL PCB is populated with through-hole components, so any repairs would be a doddle.
Certainly each motor type will have its own loaded speed drop vs supply current curve at a given rpm.
Belt slip then adds another layer of complication
This means that any controller needs to be customised to set the best negative resistance
Seems like our DC Motor Speed Controllers need to have a second “load” pot next to each current fine-tune speed pot - 33RPM pot and 45RPM pot - in order to dial-in best load for each speed.
Just out of interest, does anyone have an informed or empirical opinion on whether competent SWITCH-MODE (DIGITAL) POWER SUPPLY or competent LINEAR (ANALOG) POWER SUPPLY is superior for the specific purpose of providing stable DC to a DC Motor Speed Controller?
The OL controllers seem to be quite happy with a wide range of different motors operating over quite a wide voltage range.
The DC200 (Premotec 18105) has a terminal resistance of 12.5Ω and speed constant of ~320rpm/v. With OLs pulley fitted I was running at ~1.5v, with my DIY pulley it was down to about a single volt.
The Maxon Re-Max 226764 has a terminal resistance of 104Ω and a speed constant of 56.8rpm/v resulting in an output voltage of over 5volts.
Speed seems to be very stable with both motors. The sound with the Maxon is "more rock solid" but think this is more tonal rather than speed stability.
Niffy
The DC200 (Premotec 18105) has a terminal resistance of 12.5Ω and speed constant of ~320rpm/v. With OLs pulley fitted I was running at ~1.5v, with my DIY pulley it was down to about a single volt.
The Maxon Re-Max 226764 has a terminal resistance of 104Ω and a speed constant of 56.8rpm/v resulting in an output voltage of over 5volts.
Speed seems to be very stable with both motors. The sound with the Maxon is "more rock solid" but think this is more tonal rather than speed stability.
Niffy
Niffy,
the question is how we can get the best out of a motor. If it is the O/L controller, can we further improve it with a linear power supply or a SMPS? Alternatively, instead of the O/L controller can we use a negative resistance controller, that may perhaps (or not) play better?
I am confident that by sharing our experiences, we may home in on the 'ideal' solution (if there is one).
Panos
the question is how we can get the best out of a motor. If it is the O/L controller, can we further improve it with a linear power supply or a SMPS? Alternatively, instead of the O/L controller can we use a negative resistance controller, that may perhaps (or not) play better?
I am confident that by sharing our experiences, we may home in on the 'ideal' solution (if there is one).
Panos
There shouldn't really be any difference between a well designed and built smps and a linear supply. There does seem to be a bias against smps as historically they have been noisy. High quality modern smps can be every bit as good as their linear counterparts. My power amps use smps. I built a linear supply for my controller for two reasons. I don't have the design skills to build a smps. I had most of the components required to make my linear supply. The OL controllers seem to like a supply with a high current capability.
Niffy
Niffy
David,
I suppose you are referring to speed drift, which could be mitigated by the controller.
Stylus drag may be impossible to counteract with the controller, because the controller will always 'react' to instantaneous decelerations due to drag. To mitigate stylus drag, probably it's better to have high platter mass, that is less prone to stylus drag effects in the first place.
My two cents.
Panos