Good to see our trusted team here.
I am convinced that we will solve the motor issue in one way or the other.
I am convinced that we will solve the motor issue in one way or the other.
MiiB,
And why, pray tell, would you have 20 motors for turntables? That sounds like more than a personal diy supply?
Steven
And why, pray tell, would you have 20 motors for turntables? That sounds like more than a personal diy supply?
Steven
Audio Asylum links
For the second time in two days I picked up a virus warning when I went to an AudioAsylum page. (This time in following the link) The warning says it's an HTML virus and labels it 0DAA0d01. Maybe nothing, maybe not. I don't know much about this stuff but I thought it worth mentioning just in case.
For the second time in two days I picked up a virus warning when I went to an AudioAsylum page. (This time in following the link) The warning says it's an HTML virus and labels it 0DAA0d01. Maybe nothing, maybe not. I don't know much about this stuff but I thought it worth mentioning just in case.
When I found out that Pabst stopped making the two pole "Ausenlaufer", I bought some of the remaining stock. It runs on 24 V AC.
How about forward-feeding the audio signal to the motor controller? That way,, heavy bass pulses (slowing down the platter) could be compensated at least to a first order. Won't work with belt drive because of the time delay and the "lowpass" function of the belt. Also, the audio signal arriving is after the fact - the platter has already slowed down at that moment. But this might make a small improvement....
thoughts?
thoughts?
That is a crazy idea. That would require to delay the audio signal.
Over at the Frickelfest Forum we are working on something that could do it.
It is an A/D converter where we do the EQ in the digital domain. It is called Pandium.
We could implement delay in the DSP.
On the other hand our platter is really heavy and i think it will not slow down with heavy pulses.
Over at the Frickelfest Forum we are working on something that could do it.
It is an A/D converter where we do the EQ in the digital domain. It is called Pandium.
We could implement delay in the DSP.
On the other hand our platter is really heavy and i think it will not slow down with heavy pulses.
Premotec has ironless brush less DC motors with good torque and low revolutions, I used some of those in a CD loader/tray I designed for a well known Danish company. Current controls the RPM.
http://www.premotec.com/pdf/coreless/CL29-3 Watt.pdf
A superb solution could be to make a FLY wheel and optically read the speed of that, then close loop controlling the current through the motor(s)
http://www.premotec.com/pdf/coreless/CL29-3 Watt.pdf
A superb solution could be to make a FLY wheel and optically read the speed of that, then close loop controlling the current through the motor(s)
Mmmm... 🙂 I'm not so sure about that. A frequency locked AC motor can only run on one speed, and this speed is dictated by the power supply frequency. When using a AC generator you have all control in the world over the running speed, and being frequency locked, the motor can not run at an other speed then the requested one. DC motors can run at any speed and this speed is not controlled by the DC-supply voltage and/or current, the speed average is set by the DC-supply, and the mass of the motor (if belt driven (I think)) will give it some stability. In my opinion a AC motor is a safer bet. Where are those ATL guy's when you need them 🙂
In other words, I would like a high mass AC motor (one of those 'ausenlaufers' would be great).
Roehren-und-Hoeren :: Thema anzeigen - Luxusnetzteil für Synchronmotoren mal anders
This is good for a 24v motor, very good indeed. In fact it's the second best TT psu I've tried.
This is good for a 24v motor, very good indeed. In fact it's the second best TT psu I've tried.
The problem with AC-motors is that they need a fixed phase shift but a variance in currents so it's difficult to have a pure sine and cosine linked to the same angle through a capacitor switch, current distortion gives motor vibrations.
SO A capacitor phase shift is only the second best option, better is to make an adjustable oscillator with opamps where you have the corresponding sine/cosine, then the signals can be amplified to +-24V through two TDA amplifiers. Think there may be some usable schematics here at DIY.
The KING solution would be a FLYwheel driven by three "ausenlaufers" each driven by its own sine/cosine shifted 120 degrees, so the two pole motor gets the smoothness of 6 poles, while maintaining the speed of the 2 pole
SO A capacitor phase shift is only the second best option, better is to make an adjustable oscillator with opamps where you have the corresponding sine/cosine, then the signals can be amplified to +-24V through two TDA amplifiers. Think there may be some usable schematics here at DIY.
The KING solution would be a FLYwheel driven by three "ausenlaufers" each driven by its own sine/cosine shifted 120 degrees, so the two pole motor gets the smoothness of 6 poles, while maintaining the speed of the 2 pole
We may be able to find a nice 3 phase AC motor. Then use a signal generator, probably digital control (as stated before).
As an other thought, what about a motor like the one's that are used in lenses (like Canon ultrasonic motor), we could have many, many, many poles, They have good torque, and can be speed controlled. Any one? thoughts about this please.
High pole count is not really good unless you want to drive the platter directly. What you really want is many poles with the speed of few.
The taco controlled Ironless DC motor is not a bad choice, that Premotec motor runs really smooth, but in terms of regulation you need something that is intelligent so it reduces current as speed approaches correct. That way you can avoid the low frequency speed fluctuations that can occur when you try to regulate a heavy and slow system with a fast and powerful regulator.
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