TT Motor Controller

BlkNotes · « **Reply #20 on:** 16 Mar 2009, 08:25 pm »

Hello Jim;

What is the benefit of 3 phase over 1 phase? Would one not need 3 phase service coming into the house in order to accomadate the 3 phase motor. I know a 3 phase motor runs cooler and more efficiently then a comparable 1 phase. So I am presuming less vibration etc...

I would prefer 0.01 readablity with a digital display. Will it cost much more versus 0.1 ?

Thanks
BN

Galibier_Numero_Un · « **Reply #21 on:** 16 Mar 2009, 08:57 pm »

Thanks Brad. What part of the country are you located in?

When Jim decompresses from his vacation, I'm sure he'll have a whole lot more to say about three-phase, but here's the condensed version for BN and others ...

The output (3-phase) is unrelated to the electrical service feeding it. Ultimately, you're rectifying what's coming out of the wall and turning it into DC, or alternatively (my preference) you're starting with a battery supply and dispensing with the distortion in the AC waveform along with any residue ripple from the rectification process.

Jim can comment much more intelligently than I can, but the above is the gist of it.

The theoretical advantage of three-phase over two-phase is that the pulses pushing the motor are spaced 120 degrees apart (3 pushes per revoluton) instead of 180 degrees apart (2 pushes). Think in terms of the inherent smoothness of an inline 6 engine vs. an inline 4 (or a V-12 vs. a V-8). Larger motors tend to be three-phase, in part to control vibration.

Cheers,
Thom @ Galibier

ecir38 · « **Reply #22 on:** 16 Mar 2009, 09:08 pm »

Hey Thom,

I'm in Algiers, La. and the club member I was talking about (Tom) lives in Kenner. Both are just a few miles from the CBD of New Orleans.

Brad

hagtech · « **Reply #23 on:** 17 Mar 2009, 04:50 am »

Quote

What is the benefit of 3 phase over 1 phase?

Yes, it has to do with smoothness of torque. The interesting thing with three phases of sinewave, each 120 degrees apart, they add up to zero! That's a cool thing. Hence WYE-DELTA transformers and such. I have to look into this type of motor, but it might just end up with a relatively constant torque. You don't get that with single-phase, where the torque is most likely proportion to the sinewave shape.

Meanwhile, I did some thinking on the plane ride home. Came up with the idea to display both voltage and speed in percent. That is, for the 33.3 setting, a 60.000Hz output would correspond to 100.0%. Then you adjust up or down by up to a few percent, probably in increments of 0.1%. Output voltage would do the same thing, but over a greater range. On power up, the processor would measure the incoming frequency (50 or 60Hz) and automatically adjust accordingly.

jh

tubesforever · « **Reply #24 on:** 17 Mar 2009, 07:22 am »

A three phase motor will provide greater start up torque and the motor will potentially run with lower resonance.

In America we have a single phase power grid, so my 3 phase turntable motor uses a faking capacitor to provide the third leg so the motor will turn.

However the capacitor does not provide a perfect 120/240/360 signal so my motor runs hot and a little less than perfect timing wise. Jim can design a three phase motor control that will provide a high quality timed signal at 120, 240 and 360 degrees. This will provide smooth torque and that is good for an idler turntable. I have several Papst three phase AC hysteresis motors which are great turntable motors given the right contol timing. That is where Jim comes in.

BTW I also have the Ashland single phase hysteresis motor which also sounds amazingly nice. This is why I want Jim to build a single phase AC motor controller with frequency and voltage variability. This would also be great for those with a VPI since HW is using a 300 rpm AC motor in his upgraded turntable offerings.

For those with a DC synchronous motor, Jim can design something to give you better sound as well.

Here is a link to some information to get you started. This is just the basics. The important thing to remember is that the motor control will deliver better speed control, speed adjustment, and this means better bass lines, better midrange timing and just plain out FUN!

http://en.wikipedia.org/wiki/Three-phase

analog97 · « **Reply #25 on:** 18 Mar 2009, 11:27 pm »

Tubes,

Thanks for a helpful simplification of the advantages of this soon-to-be-released Hagerman product. I am all ears when it comes to potential improvements in analog reproduction. Put me down for a pre-order. If I gotta drill holes in a metal case, I'm ready now, having just bought a few step-drills.

dmcgown · « **Reply #26 on:** 30 Mar 2009, 11:51 pm »

Please add me as another interested party for the 3-phase controller. I am driving my Teres with a Pabst 3 phase motor (Tascam RtoR capstan motor), and have been considering a motor drive project for some time. Currently using a VPI SDS with the motor as a 2 phase motor (w/phasing cap).

David McGown

hagtech · « **Reply #27 on:** 31 Mar 2009, 06:58 am »

Oh no, been lazy lately. Spending all my time re-issuing the CHIME (in silver/black), filling orders. Haven't made any progress yet on motor controller. Right now I'd like to decide on the processor to use. I'm partial to the PIC, and pretty much selected one for that major HAGLABS preamp I never did. Also working with a Rabbit board for something else, which is very handy, but I think overkill and not quite right fit. I like the Harvard architecture of the PIC, as it lets me control timing explicity well for critical operations. Well, not so much for chips in this design. So far, I have lots of transformers. Thinking of running the whole thing high voltage (no step-downs). Just create some +/-170V rails, then 1:1 ratio for output trannys. Make myself a high voltage discrete FET amplifier to drive them. I think it will provide better coupling to motor. At the moment, trying to imagine all of the interactions / impedance / EMF etc. between motor, tranny, wiring, and amplifier.

jh

SoundBound · « **Reply #28 on:** 31 Mar 2009, 12:45 pm »

Hi Jim

Can't wait to see the motor controller project (hint, hint

). I see you were looking to use the PIC controller. I know that the Atmel AVR series of microcontrollers is very popular and uses a 'modified Harvard Architecture'. I like using it with my Arduino projects. Curious about whether you have familiarity with Atmel's AVRs and if you do, why you might prefer the PIC over them? The Atmel chips really provide many 'flavors' for a good design fit and the built-in ports and I/O features are quite amazing.

heartm8 · « **Reply #29 on:** 4 Apr 2009, 12:00 am »

disregard my Haglabs and Blog questions, Jim already answered them.

I haven't posted in a while, so I have a few comments. My first suggestion is play records on a Technics MKIV 1200 with an ortofon transcriptor cartridge. No cartridge adjustment, it works and measures better than any of the jillion-dollar belt drive contraptions out there with 80 kg machined acrylic platters and crazy tonearms. Many of the old wives tales about direct drive are just that, and tons of engineering research went into the design of these turntables. This is one area where DIY just cant match. I know Jim believes in measurements and IMHO, turntables is one area where measurements audibly matter. Wow and flutter directly affect sound greatly, and most belt drive guys wont even dare publish specs which are hundreds of times worse than a technics. I have probably $60k worth of gear, and I believe turntable tweeking is the genesis of the tube, cable and power supply tweek-o-philes. And yeah, I have a high-end belt drive, and its in a box in the closet, my Technics is what I use. I don't want to deny those of you who want to have a gleaming contraption and wash your records with a machine. I just bet in a double blind test, nobody could pick your turntable over my dishsoap and shammy and technics 1200.

I have one suggestion for Jim, because there are turntable DIY guys who will buy this. There are some very cheap clock-radios made by emerson, and I love the projection display. I would love to see a display which is a LED projection on the wall. If you're asking for input, project the track number (can you program a logic controller which can count gaps on an LP?) on the wall with the RPM speed, that would be cool. I wake up at night, and have the time and temp projected on the ceiling in 1 foot tall digits. BTW Jim, where's your blog? I miss it. I want to hear some Quad ESL-67's through that new mono amp you built with the 300B mod. I checked the haglabs site, its all gone? I guess the economy? Best wishes.

hagtech · « **Reply #30 on:** 4 Apr 2009, 11:25 pm »

Quote

display which is a LED projection on the wall

Well, it's not really my style.

Quote

BTW Jim, where's your blog?

Mostly the result of a divorce. When I can find the time, I'd like to start it up again.

jh

Galibier_Numero_Un · « **Reply #31 on:** 24 Apr 2009, 05:09 am »

Quote from: heartm8 on 4 Apr 2009, 12:00 am

Many of the old wives tales about direct drive are just that, and tons of engineering research went into the design of these turntables.

With all due respect, I beg to differ with your analysis. In audio, fashions shift almost as quickly as clothing fashions do - push-pull, single ended, direct drive, belt drive, idler drive, perfect sound forever, analog ... you name it.

In my experience, I continue to see convergence across seemingly competing architechtures, with no clear winner - only clear preferences. While the basic characteristics of a chosen architecture are evident, components designed by competent designers who have a clue about what music sounds like sound far more more alike than they do different.

Surely, differences will be heard. A box speaker will typically image better than a horn, and a horn will have superior dynamics and noise floor, and will charge a room with air the way that a box speaker cannot. The the better the expression from each design school, the more they will be alike than they will be different.

On the topic of the ineherrent inferiority of belt drive turntables, I offer the following annecdotal comments.

One of Frank Schroeder's good customers runs a Loricraft 401 and 501 - each with its own dedicated Schroeder Reference tonearm. The two turntables sit on a wide shelf, adjacent to each other. Frank suggested an experiment - that one turntable serve as a motor drive for the other one - linking the two with a thread serving as the drive belt. This customer hasn't looked back and continues to run his rig in this manner.

Do I look at this as an inherrent superiority of belt drive over idler drive? Not necessarily.

Another case ...

Most of Doug Sax's work was mastered with either a Scully or Neuman lathe. A few different motor drive systems were employed for the Scullys. One of them comprised a series of cloth belts. In another configuration at The Mastering Lab, he drove two lathes with a third one - in the manner of Frank Schroeder's experiment with his customer's Loricrafts.

There's more than one way to skin a cat.

Cheers,
Thom @ Galibier

Sonny · « **Reply #32 on:** 29 Apr 2009, 11:33 pm »

This thread is very interesting...I've been looking into the Mark Kelly controller and even tried contacting Mark, but have failed to get a reply. Therefore, I am absolutely interested in where this thread may lead!
Thanks and looking forward to it.
T

Berndt · « **Reply #33 on:** 29 Apr 2009, 11:57 pm »

ditto kiddo

somejoe · « **Reply #34 on:** 5 May 2009, 06:53 am »

Jim,

I volunteer to be one of your beta testers. I have the standard VPI motor on my TNT-5 and have been looking for a replacement for the VPI SDS for some time now. Last time the SDS went bad (speed started fluctuating) it cost me $400 for a replacement one - VPI says these units are not repairable, so they just replaced it.

BTW, I also have the Pabst 3-phase motors, so I could test that as well.

Let me know.

hagtech · « **Reply #35 on:** 6 May 2009, 05:26 am »

Ugh, sadly I've made no progress on this front yet. Hmmm, an unfixable item usually means it was made somewhere else?

jh

Sonny · « **Reply #36 on:** 6 May 2009, 02:17 pm »

Quote from: hagtech on 6 May 2009, 05:26 am

Ugh, sadly I've made no progress on this front yet. Hmmm, an unfixable item usually means it was made somewhere else?

jh

Jim, here's hoping you make some progress on it..we are all in anticipation of it!
Tuan

Berndt · « **Reply #37 on:** 7 May 2009, 01:38 am »

+1 for a controller adaptable for the Pabst in the empires...
I can do the major speed changes with pullies, fwiw.

bmckenney · « **Reply #38 on:** 28 May 2009, 11:50 pm »

The Walker speed controller also has an absolute phase switch apparently works quite well but I have no idea what absolute AC phase is.

And to me indicators aren't required and if it keeps the cost and complexity down, I would prefer not to have them. Provide the ability to adjust the frequency so a person can tune the speed of the table to exactly 33.3 and we check it with the likes of an DC strobe like the KAB. And throw the best technology at regenerating superb AC power.

If you want this to be popular, it should be as good as a Walker controller. I've tried a VPI SDS on a Nottingham motor and the benefit was marginal. And I've heard a Walker spanks a VPI with this motor. So thats the bench mark. If you can produce a kit that is as good as or better than a Walker, for a reasonable price, it should take the market by storm.

Bryan

hagtech · « **Reply #39 on:** 31 May 2009, 07:03 pm »

Thanks, I'll take a look at the Walker.

jh