TT Motor Controller

hagtech · « **on:** 4 Mar 2009, 05:13 am »

Starting a new thread for this, so I can ask for input. Decided this will be the next kit. My goal is to have working model for sale at RMAF09. Will have two variants, or perhaps one board can be built in two ways: single-phase or three-phase. Thinking about what features it needs. Voltage output will be variable, and of course frequency. But what should the display read? Instead of 60.0Hz, I'm thinking it should just be 33.3. What increments do you think are necessary? 33.3 to 33.4 or 33.33 to 33.34? I'm leaning towards that 0.01 rpm resolution. Rotary knobs such that it has an analog feel, even though the circuit is quartz locked digital.

Can be built for 50/60 Hz, 120Vac or 240Vac. I could add a strobe output (add external LED).

My friend Stu mentioned running 45 and 78 rpm too, so that would mean output frequencies of 81Hz and 140Hz. I'm wondering if the motors can handle this, or will they get too loud? I'll have to experiment on my Rega. Would be a really cool feature if you could do this with a flick of the switch, no pully or belt changes. I'll have to look into this, as the motor cap might be tuned to the one frequency. With the three-phase it's no problem.

The single-phase version would be plug-n-play. Just connect TT motor to it's outlet. Maybe I make a new UFO clamp to go with it.

jh

SHIF · « **Reply #1 on:** 4 Mar 2009, 05:26 am »

An excellent product idea, I'll buy one for sure.

I like the RPM display format, .01 resolution.

-S

My Cornet is five years old and sounding great!
Has the CCS mod, 370BX, and lots of boutique bits including the popular Russian FT-3 bypass caps.

galyons · « **Reply #2 on:** 4 Mar 2009, 06:14 am »

Jim,
This is great! 45 RPM would be convenient. 78 RPM, in my case, would not be of value. I suggest keeping the design simple, just to maximize TT speed consistency. I am assuming the LED stobe would be on an umbilical cord? Not sure if really necessary.

Thank you for soliciting input!

Cornet 2 is pretty much built. Mm DIY case is slowing my progress. Who da' thunk??!!

Cheers,
Geary

BobM · « **Reply #3 on:** 4 Mar 2009, 01:08 pm »

Jim, a couple of thoughts, after having built Mark Kelly's controller.

- 33 and definitely 45, but you should make them independently adjustable if possible
- you will need a startup period of about 7-10 seconds where the voltage is higher (@115-120V), then it can taper down to a cruising speed around 70-80V
- the display could prove interesting, since different spindles may need adjustment one way or another, so one tables 33.3RPM might spin faster than another, so Hz might prove to be more universal
- One problem that Mark tried to solve was to adjust each phase leg of the AC to smooth them out. As you know, the motors "approximate" the phase angle using a cap and resistor network. This is not ideal and can still cause vibrations in the motor if the legs are not exactly opposite phase from each other, and they rarely are with this approximation. Unfortunately this is not a plug and play option, requiring the builder to remove this cap and resistor network and hardwire the motor to the speed controller, where the phase could be independently adjustable. Not sure if it would be possible to make this plug and play or if it is something you just have to live with.
- It would be great if you could build the controller so that the adjustments are made in the digital domaine, where they would be more stable and precise and less prone to the AC variation coming from the wall, then convert to the AC "analogue" signal to drive the motor
- the incoming power supply should be regulated to assist with this incoming variation in power from our walls
- you'll probably need to provide a good quality cardboard speed disk with the kit with both 33 and 45 rings marked, or a UFO accompanyment
- 120V and 240V to accommodate all shores

Good project. Make sure you test it on a variety of tables/motors.

Bob

Dan_ed · « **Reply #4 on:** 4 Mar 2009, 02:07 pm »

Jim,

I like where this is going, especially for the 3-phase motors! I'm all set with DC. But I do have one question and I hope some of you guys might know the answer. Where can I source a suitable 3-phase motor?

The start up voltage that Bob mentioned isn't that big a deal to me since I always start my platter by hand for many reasons. But I realize I'm probably in the minority on this.

I like the speed resolution idea. I have a strobe disc marked in similar fashion.

reuben · « **Reply #5 on:** 4 Mar 2009, 02:09 pm »

I'm presently more interested in a DC motor stabilizer, but I don't know if there is a viable market.

Regards,
Tom

analog97 · « **Reply #6 on:** 4 Mar 2009, 02:36 pm »

Quote

Maybe I make a new UFO clamp to go with it.

Just a practical point. There a lot of TT's that require use of a reflex record clamp, e.g. VPI. Since I switched from a Rega to a VPI, I am no longer able to use the UFO. Hence, a UFO add-on should be optional I'd say.

MusicMtnMonkey · « **Reply #7 on:** 4 Mar 2009, 03:37 pm »

My opinion is don't worry about 78 RPM speed control. Many people would use an older TT that was originally designed for adjustable speed to play their 78's. Since those old 78's were meant to be played with a heavier arm and heavier cartridge, it's not really optimal to use a Rega or VPI anyway.

As a VPI owner, it would be really nice if the speed control would switch between 33 and 45 RPM (so I don't have to mess with moving the silly belt anymore). I think the VPI and possibly the Project speed controllers do this already, so maybe we can assume the motor is ok with it...

I didn't see the UFO on the Hagtech website, do you still sell them?

ecramer · « **Reply #8 on:** 4 Mar 2009, 04:04 pm »

now if the ufo came with a 1/4 20 screw down us VPI owners would be covered as an option of course. This is definitely a kit project that i would be interested in doing.

ED

ecir38 · « **Reply #9 on:** 5 Mar 2009, 03:45 am »

Quote from: Dan_ed on 4 Mar 2009, 02:07 pm

The start up voltage that Bob mentioned isn't that big a deal to me since I always start my platter by hand for many reasons. But I realize I'm probably in the minority on this.

A friend has a Nottingham spacedeck that starts and stops by hand. I don't have any first hand experience to offer but may find this little bit of info usefull.
http://www.aslgroup.com/nottingham/manual/faq.htm#WAVE_MECHANIC_POWER_SUPPLY

What about a line isolator like the Vpi? I have heard that the clean power it provides makes a big differance.
http://www.vpiindustries.com/products_sds.htm

We'll be following this one thanks Jim.

Brad

tubesforever · « **Reply #10 on:** 5 Mar 2009, 09:16 am »

For a three phase motor controller, i think just plain knobs for the control without any display would be fine. Jim, I plan to use a strobe to verify speed, so the display on the motor control might simply be too busy for a vintage analog guy like myself. Can you make the display part optional?

For a single phase motor control can you use the same circuitry for a shaded pole motor as for an AC synchronous motor? My Rek O Kuts uses shaded pole motors and these sound really good. The voltage determines the speed. It would be nice to have a wide voltage swing, so I can machine a larger pulley and run the motor closer to 75 to 100 volts to reduce resonance.

As Bob mentioned, the VPI controller starts at wall voltage and then drops to a lower voltage in order to reduce motor resonance. Can your kit provide the same start voltage with an automatic drop to the steady state voltage? Can you build that dropped down voltage level to be controllable like VPI has done on their SDS control?

If you can create the three phase motor kit I will be forever indebted! This is a very important project that would make a very favorable improvement in my system!

The single phase motor kit is nearly equally important to my vintage turntable projects as long as it will work with a shaded pole motor configuration.

Cheers!

Dan Ed....One of the best three phase motors ever built was the Papst Hysteresis motor. You find this on Empires, Rek O Kuts and Oracle tables. You also find a larger version of the motor in sellect R2R decks.

I have three of these now. I have two from Rek O Kut N-33H belt drives and one in a Rondine B12GH. I am using the Papst motor in my thread drive table. Here is a picture of the motor.

The faking cap is there to supply the third leg of the three phase supply. The three phase motor supply would provide a more stable and accurate phasing for the motor. You can see the inner drum of the hysteresis motor. This spinning portion produces a flywheel effect that provides for better inertial performance than a traditional motor.

I put this motor into a customized motor pod and machined a pulley for accurate thread drive speeds with my 120 v power.

This is my favorite record player at this time.

alpa6 · « **Reply #11 on:** 5 Mar 2009, 06:14 pm »

i'M NOT SURE about some of what you talking about jim but to me if you apeal to the widest range of people ypu will sell more.So i say 78,45,33.3 rpm.
As far as a display my scout depending on how tight i make the belt will run a different speed.
I would like the motor controler to run 33.3 no matter what.
If this is possible.
I dont care about fliping belts it's not big thing to move it.
Is this going to be a tube unit.
I figure it must be ss.

Dan_ed · « **Reply #12 on:** 5 Mar 2009, 08:11 pm »

Thanks, tubes. I'm looking for a source of new 3 phase motors.

As for the starting by hand, to me this is more of a means to save belt life rather than any deficiency with motor or controller. I use modified mylar for belts and the textured side lasts longer if I avoid the capstan spinning away while trying to get the 32 lbs platter up to speed.

SoundBound · « **Reply #13 on:** 5 Mar 2009, 08:19 pm »

Sounds like a great project. Once the kit comes out, I would really like it if you can suggest a supplier, or perhaps supply, some good motors (single and 3 phase) for use with the controller and if an LED is provided for strobe control, then the availability of an appropriate strobe disk or mat would be great.

Looking forward to see what come out of the 'witch's cauldron'.

SCompRacer · « **Reply #14 on:** 5 Mar 2009, 09:57 pm »

Quote

A friend has a Nottingham Spacedeck that starts and stops by hand.

Tom Fletcher of Nottingham believes in using low torque motors. I don't mind the starting and stopping of the platter by hand. I started out with a Spacedeck and then to a Space 294. The speed was near dead on with the Spacedeck, but near .3% fast with the 294, so I picked up a demo Wave Mechanic. Controllers sure can be pricey, so it will be interesting to see what Jim comes up with.

I’m with tubesforever; I don’t need a display. On my current controller, I just have a knob to adjust frequency (the voltage is fixed). I use a KAB Speed Strobe to monitor the platter speed. I check it now and then, but haven’t had to readjust it. I love the Speed Strobe as it is easier for me to look at the numbers instead of the hypnotic lines.

Perhaps a display would be nice once you find the best voltage/cycles setting for your motor and return to if they were changed. (I've never had a VPI controller so I don't know if you lose settings if the controller is powered off).

TheChairGuy · « **Reply #15 on:** 5 Mar 2009, 10:02 pm »

Quote from: SCompRacer on 5 Mar 2009, 09:57 pm

(I've never had a VPI controller so I don't know if you lose settings if the controller is powered off).

You don't lose the settings I don't think if powered off...I had one here for a month from a friend (nice fella' eh?) and it worked out quite well.

Jim (Hagerman) - would there by a fully constructed option, too for this if you produce it? Or would it not be plug in and play due to nature of the 3 phase regulation? In which case, it would be beyond my meager capabilities

John

SCompRacer · « **Reply #16 on:** 5 Mar 2009, 10:15 pm »

Quote from: TheChairGuy on 5 Mar 2009, 10:02 pm

I had one here for a month from a friend (nice fella' eh?) and it worked out quite well.

That is nice! Where would we be if it were not for our friends?

Tone Deaf · « **Reply #17 on:** 6 Mar 2009, 09:32 pm »

I'm eager with anticipation!

I have a Linn LP12 so interested in single phase I guess, running 240v @ 50hz. 33 & 45 rpm at flick of a switch would be fantastic.

Any plans to include some tubes Jim?

Glyn

Galibier_Numero_Un · « **Reply #18 on:** 16 Mar 2009, 06:56 pm »

Hi Jim,

It was good to catch up with you for a few turns at Breckenridge yesterday.

There's a small group of Galibier owners (amongst whom, Dan_ed is a key contributor) who has been experimenting with driving a turntable. To date, we've played onlly with the Mark Kelly controller (both AC and DC).

The group is diverse in their musical tastes and system architecutre (there are representatives of the box speaker, horn, and planar camp). Of course the commonality is the Galibier connection.

In any event, no clear preference has emerged, as far as conveying all types of music the "best". A three phase controller is certainly on the short list - if we can source a motor in current production. The Kelly controller to date has driven two different two phase motors.

One other theme that is just now beginning to emerge is to run the motors much faster than they have been specified for. Heresy you say? Well, it's already being done when you throw a higher frequency at the motors to spin the the platter at 45 rpm.

This higher speed has the effect of shifting residual vibration to a place the Galibier architecture is filtering it out. My guess is that even low mass, sprung designs would benefit from this as well - with their resonant frequency lying in the 4-5Hz range.

While I can of course manufacture any pulley size I care to, the question arises as to how the purchaser of a Hagtech product can do so as well.

Well, taking the LP12 for example, the Primotec motor uses a Europen standard, 3mm motor shaft - something I've been machining for the Maxon DC motors we've been using. The Hurst motor used in the VPI has a .125" shaft, and I've machined pulleys for these as well. When you begin prototyping this, I can send you pulleys to fit most motors, and manufacturing them for you would likely present no problem.

The intent of this thread is of course to consider an appropriate, adaptable architecture - to not close up ones design options prematurely.

I contend that we should not limit our choices of speed to those dictated by motor manufacturers. These motor manufacturers do not design their products for turntables. You'd be amazed at the discussions I've had with the Maxon engineers. More times than not, their recommendations have been 180 degrees opposed to what we've found to sound best.

Similarly, running AC motors out of spec could have its sonic advantages.

Cheers,
Thom @ Galibier

ecir38 · « **Reply #19 on:** 16 Mar 2009, 07:42 pm »

Thom, thanks for chiming in with your input. One of our local club members is having a meeting next week and has your Gavia turntable, Triplanar mk iv arm with a ZYX universe mc cartridge. Should be a treat.

Brad