I'm jumping in the deep end tackling a BLDC controller circuit to replace the original analogue controller of a Technics SP10 MkII turntable. If it is assumed that I can successfully emulate or even improve (!) upon the stock circuit's performance, what additional features would you deem desirable in such a controller?
It is likely to be (but needs not be) a stand-alone controller that bypasses the on-board switches and replaces the existing power supply.
Your ideas, please...
It is likely to be (but needs not be) a stand-alone controller that bypasses the on-board switches and replaces the existing power supply.
Your ideas, please...
Yikes!! No takers?
OK, let's start:
1. Start/stop button (single or separate?)
2. Variable speed dial/slider (variable by what %age?)
3. Four user-presetable speed buttons
4. Reverse function (could be dangerous!)
5. Electronic Brake for stop function
6. Hold/ free platter when stopped.
Questions:
Should the controller (or a version of the controller) use the existing on-board controls or be self-contained?
Should it use own power supply or the existing unit?
OK, let's start:
1. Start/stop button (single or separate?)
2. Variable speed dial/slider (variable by what %age?)
3. Four user-presetable speed buttons
4. Reverse function (could be dangerous!)
5. Electronic Brake for stop function
6. Hold/ free platter when stopped.
Questions:
Should the controller (or a version of the controller) use the existing on-board controls or be self-contained?
Should it use own power supply or the existing unit?
Hello Shaun,
Have you started on this project? I know that if you take this to other forums (vinyl asylum for example) you would get much more attention.
I for one would love to be able to have "
1.) a modern power supply
2.) speed control (at least within 0.1% increments, and with knob not slider)
3.) Remote control
4.) Would also like some sort of "umbelical cord" made so that the tables' electronics can be isolated from the plinth, giving it even better performace.
I have 2 SP-10 MKII's both mounted on the factory Obsidian plinths...
Keep in touch!
Rick
Have you started on this project? I know that if you take this to other forums (vinyl asylum for example) you would get much more attention.
I for one would love to be able to have "
1.) a modern power supply
2.) speed control (at least within 0.1% increments, and with knob not slider)
3.) Remote control
4.) Would also like some sort of "umbelical cord" made so that the tables' electronics can be isolated from the plinth, giving it even better performace.
I have 2 SP-10 MKII's both mounted on the factory Obsidian plinths...
Keep in touch!
Rick
Hi Rick
Finally(!) some interest! I have not really progressed beyond looking at what the options are among the various controller chips. The project is still on, though it is competing with others for available time. Over at VinylEngine there is a(nother) member developing a controller, though I suspect that it will be a commercial product.
Thanks for the encouragement. I'll post some info as soon as there is more movement on this project.
Finally(!) some interest! I have not really progressed beyond looking at what the options are among the various controller chips. The project is still on, though it is competing with others for available time. Over at VinylEngine there is a(nother) member developing a controller, though I suspect that it will be a commercial product.
Thanks for the encouragement. I'll post some info as soon as there is more movement on this project.
Hey Shaun
The motor I got at a spares shop close down sale - its an unused replacement for the SP10ii - the motor only, no plinth or platter.
One problem is that I dont have an original platter, so the mechanical characteristics of the motor/platter will be different from Technics' intended - hence a 'real' controller wouldn't work optimally anyway.
At some point I need to measure the behaviour of the motor to get all of its parameters!
I wanted to use a PIC (Microchip's all-in-one chip) so I can dial in the platter mass, and then use it with a variety of different ones.
The basic idea is a software PLL, with a software PID contoller - minimal analogue processing because I'm too lazy to do harware replacement of components if I need to adjust controller parameters!
First issue though is to build the three phase drive amplifier. Electrically thats not difficult, but I'd use a few op-amps rather tham all-transistor like the original. Only once I have that can I measure the motor behaviour.
The motor I got at a spares shop close down sale - its an unused replacement for the SP10ii - the motor only, no plinth or platter.
One problem is that I dont have an original platter, so the mechanical characteristics of the motor/platter will be different from Technics' intended - hence a 'real' controller wouldn't work optimally anyway.
At some point I need to measure the behaviour of the motor to get all of its parameters!
I wanted to use a PIC (Microchip's all-in-one chip) so I can dial in the platter mass, and then use it with a variety of different ones.
The basic idea is a software PLL, with a software PID contoller - minimal analogue processing because I'm too lazy to do harware replacement of components if I need to adjust controller parameters!
First issue though is to build the three phase drive amplifier. Electrically thats not difficult, but I'd use a few op-amps rather tham all-transistor like the original. Only once I have that can I measure the motor behaviour.
My eventual goal is to make an acrylic platter and plinth. To retain the quick start/stop characteristics I intend keeping the platter mass as close as possible to the original platter. If you're interested, I'd be willing to let go of my other SP10Mkii enclosure (I have two SP10's). PM me if you're interested.
Re: Shaun...
Nanook
I understood what you meant. My two SP10's are troublesome and they're not mint, being ex-ex-SABC. They also do not have original power supplies. My main gripe with the SP10's is that they are not 9- or 10-inch arm-friendly, forcing one to mount these arms at odd positions. Considering all of the above, I think I'll be forgiven for my intentions.
Nanook
I understood what you meant. My two SP10's are troublesome and they're not mint, being ex-ex-SABC. They also do not have original power supplies. My main gripe with the SP10's is that they are not 9- or 10-inch arm-friendly, forcing one to mount these arms at odd positions. Considering all of the above, I think I'll be forgiven for my intentions.
Steerpike said:
Would this be something you would sell to others that are intersted, that is, when you have finalised the prototype?
If so, would you also be able to adjust performance for different platter weights? I am planning on having a brass/aluminium platter built for one of my SP-10's, it will weigh around 28 lbs.
I would also like to seperate the electronics modules that are currentlly below the platter to a seperate box via some sort of "umbilical cable"... anyone thought about this?
On more thing, I have the "HI-FI World Supplement, Novemeber 1997, D.I.Y. Letters" printed off the net from a couple years ago. I have tried to find the site again, but no longer have the Web address, and "searchs" have turned up nothing.
Does anyone have the web address to this?
Thanks...
Rick
The project will be published for all to build. I'm not too sure how one would go about accommodating platters of differing mass. Perhaps it will turn out to be a simple setting. It seems the umbilical connection is a given.
I did stumble upon some articles once. IIRC, one suggested upgrading the regulators, and the other one recommended removing the rubber damping piece in the motor assembly. To be honest, I did not think much of those suggestions... but, as always, I could be wrong.
I did stumble upon some articles once. IIRC, one suggested upgrading the regulators, and the other one recommended removing the rubber damping piece in the motor assembly. To be honest, I did not think much of those suggestions... but, as always, I could be wrong.
I'm happy to give away freely anything information-wise I discover; but I wouldn't sell ready-made PC boards etc.
With a microprocessor driving it, adjusting the servo parameters for different masses would be a simple matter of pressing a few buttons and dialing in the number, shown on an LCD display. A display is a nice thing to have - can show the speed error, controller parameter setting etc.
I have one of the SABC "Mark3" turntables - without its motor;
my real fantasy was to get the SP10 motor into that, but at the same time not harming the Mark3 in any way - i.e., maybe a few under-platter holes drilled, but NO serious cutting of any metalwork.
The platter bearing puts the SP10 to shame!
Is it? Works for me every time even if I'm not logged into the VE - maybe VE's finding a cookie.
I doubt it would work - the Mark3 needs a FAST motor. Maybe I should keep the SP10 motor for a project on its own; the other plan was to put a PLL-controlled ReVox reel motor into the Mark3. The Mark3 has 3 idlers, one for each speed. It's quite severe on the motor bearings - there are no springs for the idlers, and no 'give' in the linkages, each selected idler is pulled hard against the motor pulley with a solenoid.
I'm in two minds about using a microprocessor in this project. The uP makes hardware things easier & simpler, but it does make it more of a niche project, since maybe not everyone has the tools and hardware to get the software into the chip.
If the software (HEX dump) is free on the WWW, would most (all?) readers have some access to a PIC or EEPROM programmer?
THEN what happens in 10 years when the particular microconroller chosen is obsolete?
If the software (HEX dump) is free on the WWW, would most (all?) readers have some access to a PIC or EEPROM programmer?
THEN what happens in 10 years when the particular microconroller chosen is obsolete?