I already provided pyramid with the "ultimate" psu design. Last I talk to him, he was available to modify his existing code with tachometer.
The thing is this, the circuit needs to be prototyped and certainly tweaked by me for max stability, so if we move forward I and pyramid have to invest a good amount of time in this, therefore I want to make sure that we have support for the mechanical design. Who will build the housing and pulley? I am not happy with a little rough tubular, I mean something well thought and design.
Also we have to settle for a specific DC motor and pulleys dim before committing to anything else.
Tonight hopefully I will find some time, I will sketch a proposal! If there are consensus we will move forward! Sounds like a plan?
The thing is this, the circuit needs to be prototyped and certainly tweaked by me for max stability, so if we move forward I and pyramid have to invest a good amount of time in this, therefore I want to make sure that we have support for the mechanical design. Who will build the housing and pulley? I am not happy with a little rough tubular, I mean something well thought and design.
Also we have to settle for a specific DC motor and pulleys dim before committing to anything else.
Tonight hopefully I will find some time, I will sketch a proposal! If there are consensus we will move forward! Sounds like a plan?
another one to throw into the pot.
why don't we use the actual record to set the speed. as far as i'm aware an ipad has an app that can tell the variation in speed by listening to tones so why don't we utilise that. A-D converter-app-motor control. this would solve the problem of variations in record production.
why don't we use the actual record to set the speed. as far as i'm aware an ipad has an app that can tell the variation in speed by listening to tones so why don't we utilise that. A-D converter-app-motor control. this would solve the problem of variations in record production.
What is the difference with plater speed provided that vinyl won't slip?
Know thing to note, the idea is to only correct for long drift not to apply continuous feedback.
Know thing to note, the idea is to only correct for long drift not to apply continuous feedback.
Bibio-
Can you expand on that a little more? Is the record a test disc with a specific tone or does it look for a periodic signal in the music? What's the resolution? Do I need to have an iPad (500 iBucks) to use it (I'd be out of luck, I don't even own a cell phone)? Where do you take the output from the app, and what format is it (analog, SPI, CAN, I²C, firewire, USB...)?
Can you expand on that a little more? Is the record a test disc with a specific tone or does it look for a periodic signal in the music? What's the resolution? Do I need to have an iPad (500 iBucks) to use it (I'd be out of luck, I don't even own a cell phone)? Where do you take the output from the app, and what format is it (analog, SPI, CAN, I²C, firewire, USB...)?
i have not got a clue about technical details i just had an idea. your probably right about a test tone so it's more that a useless idea... lol
you can get the same type of app for Android OS as well.
you can get the same type of app for Android OS as well.
long drift is not a problem any more for DC motors. much of the information 'on the net' is fairly old technology and people with the new methods tend to keep it close to their chest as there is a looooot of money to be made.
Yep I know there is a big market for DC controllers and motors.... 😉
Anyway, if you read in OL users you will see people note that it drifts overtime. L
Regarding checking vinyl speed has no useful info as you put a test note and the application determines the exact frequency. You would need to check periodically!
The tachometer is the best solution right under the platter or the pulley either way.
Maybe under the pulley gives more flexibility to most users that might not have enough clearance to accommodate the tachometer.
Stefano,
I can build the enclosure and pulleys, but as you said a decision on motor and PSU should come first. Enclosure and pulley design come from the decision of motor and PSU and motor characteristics. High torque, low torque. Quiet or noisy. Very good bushings for audio or general industrial bushings. Then we engineer the enclosure and pulleys around those conditions.
I think the motor selection should be driven by some general ideas about the platter. I think heavy and light platters have different drive requirements.
What kind of platter are you trying to drive? What is it's mass? What kind of motor do you want to use?
Is this a drive solution to retrofit retail TT's like the VPI or also for "from scratch" builds by DIYers. Is this solution to be quick, or should it have a longer vision to use newer technology like DC Brushless.
Jamie
I can build the enclosure and pulleys, but as you said a decision on motor and PSU should come first. Enclosure and pulley design come from the decision of motor and PSU and motor characteristics. High torque, low torque. Quiet or noisy. Very good bushings for audio or general industrial bushings. Then we engineer the enclosure and pulleys around those conditions.
I think the motor selection should be driven by some general ideas about the platter. I think heavy and light platters have different drive requirements.
What kind of platter are you trying to drive? What is it's mass? What kind of motor do you want to use?
Is this a drive solution to retrofit retail TT's like the VPI or also for "from scratch" builds by DIYers. Is this solution to be quick, or should it have a longer vision to use newer technology like DC Brushless.
Jamie
I think the criteria for a broadcast turntable in the 70's is much different than what this group is proposing. The 2 primary requirements for broadcasters were reliability and torque (get up to full speed in as short of time as possible). They were less concerned about noise, vibration or speed stability than we seem to be. They used big, well built powerful motors. I don't think that is the focus of this discussion. Also, 1800 RPM would pretty much leave out the (rim) belt drive crowd.
What are the design goals you guys are trying to meet? Maybe you should specify those first before deciding upon a solution.
1. Is this an aftermarket solution to address a specific table application, a broad (multiple tables/mfrs) solution, or are you looking to advance the state of the art by focusing on a particular (possibly new) TT design?
2. Is it going to be a DIY kit, finished PCB's, finished assembly with motor or complete solution including TT, tonearm and cartridge?
3. Although this thread started out as how to improve an AC synch Hurst motor, it seems that most are interested in pursuing a DC motor solution. If so, what are the requirements (volts, amps, torque, cost, etc.)? Will it have current monitoring feedback with negative resistance compensation? If so will it be analog based or digital? If digital, what is a reasonable sampling rate to remain accurate while not coloring the audio? If analog or digital, how to determine the motor conversion gain (ΔSpeed/ΔVolts) and how to adjust for this in order to incorporate a number of motors (or if this is to be an aftermarket application).
4. What is the drive configuration? Will it be (or be capable of) belt drive, idler drive, direct drive?
5. I have no experience with group buys, so I don't know this works. Should the electronics be SMT or thru-hole? What about IP? It looks as though everyone is comfortable donating their ideas; how do we keep someone from exploiting the design for commercial purposes?
Feel free to add to the list.....
Hi Jamie!
I had in mind a DC motor with high torque and low noise, very good bushing and bla bla bla...in short the works!
That's easier said than done!
I agree, we should first start on the motor choice, we can start on it today.
I will give some proposals and see what the people here think.
It would be beautiful it it was a retrofit for a table, but then it would defeat the purpose of being useful for a lot of people.
This is why I am saying that the pulley should have a clearance from the table that allows many users to use it.
Unfortunately I was extremely busy this weekend with projects that I didn't even have time to sketch anything useful. I will try to do it tonight.
For the drive, this should drive heavy platter, like 15+lbs.
I think we have the elements to move on, I will post some motors shortly ans see what the community thinks about it.
Stefano,
That sounds perfect. I really like the idea of building something more universal or something people might like for "scratch builds". But if we get something good, I can build you a nice enclosure for retrofit to a particular table. For example it could be a really nice CNC machined base that puts the motor at the right height for a particular table.
I'm very curious to learn what people think is the "best" DC motor currently available that we can use. I've been looking at only AC motors and it took forever to read everything then find out that people don't really like them anyway.
Cheers,
Jamie
That sounds perfect. I really like the idea of building something more universal or something people might like for "scratch builds". But if we get something good, I can build you a nice enclosure for retrofit to a particular table. For example it could be a really nice CNC machined base that puts the motor at the right height for a particular table.
I'm very curious to learn what people think is the "best" DC motor currently available that we can use. I've been looking at only AC motors and it took forever to read everything then find out that people don't really like them anyway.
Cheers,
Jamie
With multiple DC motors, how will you be sure that there is not one motor, or more, working as generator ?
Exactly what I was trying to say to him as well. hi-end requirements are way different from those from the 70-80s!
Let me now try to answer to your points:
1) this should be an aftermarket solution that works on multiple tables (no specific)
2) I would think that it is too complex and time consuming from the designer's side to support a kit and maybe too frustrating for people who try to build it. I feel it would be better to offer finished pre-tested assembly. For the motor assembly this will be Jamie's call.
3) You are right, this thread started by talking about something else and it turned out to be something even more interesting.Regarding the DC motor, we should just get the best (quality design is the key here). No current feedback compensation, excellent DC motor and state of art for PSU design will be rock solid. We said we are going to use a tachometer which will correct for major drifts. The goal should be to correct as little as possible. Once the model is up and running on the bench, we will be able to determine how much correction it will need to let's say achieve 0.3% or better (I think we should set a new standard for speed rotation based on quality design 🙂 ) and listening tests also will help determine what's the best approach.
4) Drive configuration will be RIM drive. With DC motor I am not sure we can allow both belt and RIM as speed will have to change significant and all the drive and code will be optimized for a certain speed of the DC motor.
RIM is the reason why we are using DC motor, otherwise we could have done a simple off board AC motor with belt, which is not the purpose of this implementation IMHO
5) This is the problem with DIY and you have a good point. GB are very easy once design is done you open up a GB thread and have people ask for as many set as they need I think the electrical designers here (you and I) should have the IP rights on this somehow to prevent other people/companies to commercialize it like any other things. The parts will be SM or TH, which I will decide when I actually start the real design work based on multiple factors. Since we are giving very likely fully assembled boards this won't matter much.
Please let me know your thoughts and all the guys here as well.
😎
we are going for the "simple" one motor solution. We felt 3 motors would be way too complex and time consuming at this point! 😉
😎
Wonderful! You are the man! I have no preference as far as enclosure. I have to study a bit different tables (which I am doing) and come out with a mechanical sketch of what the ideal pulley and enclosure will look like.
I will try to provide you with a first draft for everybody's approval.
Yes, there are a lot of DC motors out there and I am going to link some of the most significant shortly (some of them were already listed here).
Arch Stanton:
I can only speak about TW Acoustics 3 motor unit. The motors are set up in a triangular format and one motor run in reverse. It offers more than enough power to spin the 40lb platter with rock steady speed control.
Maxon offers probably the biggest selection of precision dc motors that I know. They are not cheap but high quality. Ebay at times has quite few also.
I can only speak about TW Acoustics 3 motor unit. The motors are set up in a triangular format and one motor run in reverse. It offers more than enough power to spin the 40lb platter with rock steady speed control.
Maxon offers probably the biggest selection of precision dc motors that I know. They are not cheap but high quality. Ebay at times has quite few also.
yes I am looking at maxon motors. I am looking for a powerful enough motor with low rpm/V constant with torque over 60mNm.
With the lower torque of DC motor compared to AC's, power rating has to go over 15W, which is not a problem except they cost significantly more but it is not our limiting factor in this case.
I just wonder if they are as quiet as let's say 7.5W 's one.
I talked to maxon and they were recommending the 7W motor, but I don't feel it has enough torque to make it universal and to allow us to set any type of standard of speed regulation of any sort.
Beside a good controller will need to boost more than 1V at the output and with the RIM application we want to run the motor very low RPM which technically keeps noise lower and also power dissipation on both motor and controller down.
For this reason it has to be a higher voltage DC motor.
I am thinking out loud so please feel free to comment on my criteria.
Thanks.
😎
With the lower torque of DC motor compared to AC's, power rating has to go over 15W, which is not a problem except they cost significantly more but it is not our limiting factor in this case.
I just wonder if they are as quiet as let's say 7.5W 's one.
I talked to maxon and they were recommending the 7W motor, but I don't feel it has enough torque to make it universal and to allow us to set any type of standard of speed regulation of any sort.
Beside a good controller will need to boost more than 1V at the output and with the RIM application we want to run the motor very low RPM which technically keeps noise lower and also power dissipation on both motor and controller down.
For this reason it has to be a higher voltage DC motor.
I am thinking out loud so please feel free to comment on my criteria.
Thanks.
😎
Alright, this is what I think we should use: the bad boy
http://www.maxonmotor.com/maxon/view/product/motor/dcmotor/re/re40/448591
The voltage/rpm constant is low enough to allow us to comfortably run it withe the best DC supply I can think of at about 3-4V for 33RPM 6-7 for 45RPM.
It seems to have enough torque to deal with a 45lbs platter and the bushes are the best maxon has to offer, which should translate in a quiet motor.
Running it at low revolution should make it very quiet.
Torque of the motor seems to be constant at any rated speed.
One other thing I like for this motor is the high temperature allowable, which means it has a low tempo and since we are going to run it at a fraction of the rated voltage, with a state of the art supply, the rotation should be rock solid.
The only thing I am worried about is the status shown on the specification (provisional) which I don't know if it means that the motor is yet not available or what.
Once we agree upon this one, I can call and find out.
I am thinking out loud again, so please feel free to comment. 😱
😎
http://www.maxonmotor.com/maxon/view/product/motor/dcmotor/re/re40/448591
The voltage/rpm constant is low enough to allow us to comfortably run it withe the best DC supply I can think of at about 3-4V for 33RPM 6-7 for 45RPM.
It seems to have enough torque to deal with a 45lbs platter and the bushes are the best maxon has to offer, which should translate in a quiet motor.
Running it at low revolution should make it very quiet.
Torque of the motor seems to be constant at any rated speed.
One other thing I like for this motor is the high temperature allowable, which means it has a low tempo and since we are going to run it at a fraction of the rated voltage, with a state of the art supply, the rotation should be rock solid.
The only thing I am worried about is the status shown on the specification (provisional) which I don't know if it means that the motor is yet not available or what.
Once we agree upon this one, I can call and find out.
I am thinking out loud again, so please feel free to comment. 😱
😎
- Status
- Not open for further replies.