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In Reply to: RE: Use with Lenco motor... posted by kentaja on December 17, 2016 at 08:02:52
Your first sentence says "it" works fine on your L75. I presume you are referring to the Phoenix Eagle power source. Yes? If yes, then you go on to say that you are not sure "it" will be a step forward, because of marginal power capability. That statement seems to undercut your first sentence. Can you clarify? I ask as a potential buyer.
From the reading I have now done, it appears that Phoenix developed the 25W power source precisely because their original amplifier only developed 15W which was obviously insufficient for the Lenco. If the 25W Eagle was designed with the Lenco in mind, it seems unlikely that such a capable engineer as the one at Phoenix would have got that wrong the second time around. (Not that I know this for sure.) I guess I can just go and measure the current drawn by my Lenco and calculate its power needs for myself, before going ahead with a purchase.
I've been running my Lenco L75 off of a Walker Audio Precision Motor Controller. It's a bit of a mystery how much power the Walker can deliver, but I think/thought it was somewhat less than 25W.
Follow Ups:
> I guess I can just go and measure the current drawn by my Lenco and calculate its power needs for myself, before going ahead with a purchase.
Power = Current x Voltage. Therefore, a current of 208-milliamps with a line voltage of 120-volts equals 25.0-watts.
I'd be interested in knowing what you measure. Can you keep us informed?
Thanks,
John Elison
On the same thread at Lenco Heaven where I learned to my surprise that the Lenco motor is an AC type, I also learned it draws 140mA at 110V. Thus should be no problem for the 25W Eagle.EDIT. That's about 15W.
Edits: 12/20/16
I haven't had a chance to perform this little experiment myself, yet, but searching on the internet reveals estimates of the power required by the Lenco L75 motor to be right around 20W, so there may be some substance to Kentaja's doubts, if you believe an excess of power is beneficial. Yet I also found posts by "Pyramid", which seems to be Bill Carlin's moniker on DIYAudio, to the effect that he designed the 25W version of the Eagle precisely to accommodate the Lenco, Garrard, Thorens TD124 groupies. Perhaps 25W is a conservative rating for the Eagle; for sure I do not find any dissatisfied customers using it to power their Lenco's.
I tried the Eagle/Roadrunner on my Thorens TD-124 and while the speed stability was excellent, the Eagle produced a hum into my system that was noticeable and I couldn't get rid of it regardless of what I tried.
The tachometer is what I am referring to. It works fine.
Like anything in audio 25watt may be sufficient on paper to drive the idle motor but it is not optimal. The motor will want a bigger supply.
See my response above to John Ellison.
However, I do take your reservations seriously, because I respect your experience. Can you say whether you have made measurements of the power requirements of the Lenco motor that would support your view? Or is this scuttlebutt from Lenco Heaven, which would also cut some ice with me?I've been running my Lenco off the Walker PMC, which by all accounts is slightly less powerful than the 25W Eagle. I don't notice any problem, no over-heating of the Walker or speed irregularities of the Lenco, that would point to power starvation. On the other hand, the Walker effect is not as profoundly obvious with the Lenco as it once was when I used the Walker to drive my previous Notts Hyperspace. On that tt, the Walker was a revelation.
I found this quote from "Pyramid" (Bill Carlin, I think) on DIYAudio:
"AC synchronous motors are locked to the driving frequency so the speed is controlled by changing frequency not voltage. The speed (RPM) is Freq x 60/#pole pairs. So for a 12 pole motor at 60 Hz, the speed is 3600/6 or 600 RPM. A 300 RPM motor (designed for 60 Hz) has 24 poles. We can change the frequency of the output signal in 35µHz steps so the speed control is very precise. The factory default frequency for 33.333 RPM is 60Hz, but in calibration mode, you can adjust this in 0.01 RPM steps. Once the base frequency is set, changing the "tempo" setting in 0.1 RPM steps using the +/- buttons is easy and the speed stays synchronized and accurate.AC synch motors also exhibit no loss in speed due to torque loads. They hold 100% of their speed until the cogging torque is exceeded at which point the speed drops to zero. This is not true with DC motors or AC induction motors. DC motor speed is controlled by voltage, therefore our controllers do not work with them; AC induction motor speed is a function of frequency and voltage, although the speed is not locked to the driving frequency as in AC synch motors, but is related so speed control is a little more difficult."
EDIT. I deleted a paragraph here where I said the Lenco motor was an induction type. I was wrong, apparently.
Edits: 12/18/16
I have not done any power measurements of the Lenco motor. I am sure the 25W Road Runner will run the Lenco motor just fine. And for the record I have not actually tried the RR 25W unit. My experience is with similar small wattage motor controllers.
The small wattage controllers that I have tried, i.e. 25-30W, did improve the performance of the Lenco in several areas. Better resolution, focus, less grain to the sound versus running the motor directly off the AC.
Where they fall apart for me is they reduce the qualities that make me want an idler in the first place. There is a reduction in drive, slam. Everything seems to close in on itself. Nothing terrible by any means but a step in the wrong direction IMO.
Perhaps this is the nature of the Lenco motor since as I understand it is not a true AC synchronous motor. I have a restored Garrard 401 from Grail Audio arriving this week so I can make motor controller evaluations with this machine as well.
I am still intrigued by the RR supply because of its ability to apply a feedback loop in conjunction with the tach. In this regard it is similar to the old Japanese direct drive but will not achieve the true quartz-lock performance of the better Japanese DD tables.
At the moment I am running the Lenco off a 500VA isolation transformer. This seems to give the improvement of the motor controllers, improved resolution, focus, less grain without screwing up what I like about idlers.
While RR designed the 25W unit for idlers I think there focus as a company has been more geared around belt drives and with these type tables I have no doubt it is a nice unit. The 25W unit may work very well with idlers including the Lenco. Skeptical given its limited output but no more than they cost willing to give it a try.
I plan on buying the RR 25W supply before they are all gone. If I don't like it on the Lenco, or Garrard, I can always try it on my Linn or sell it. Once the new units are gone no doubt there will be high demand for used unit.
I have a Monarchy supply on the way. This unit is rated at 100W. I have heard it on a friends Garrard 401 and liked the results. But you never know until you have it in your own system.
Then of course there are a certain number of folks that think any motor controller is a step in the wrong direction. I am thinking Linn as an example. With the introduction of the Valhalla supply there have been some that think the table sounds better with the older Basic supply. I have never tried my Linn this way just the Valhalla, Lingo II supplies. But I still have a 60Hz motor and may install this in the Linn and run it off the AC line.
What you say about the loss of "slam" and other qualities commonly attributed to idler drive turntables, when using an AC supply, is worth noting. I think the Garrard motor may be even more power hungry than the Lenco motor. Just to keep the terminology straight, the name of the power supply made by Phoenix is "Eagle". So far as I understand it, the tach made by Phoenix Eng is called the RoadRunner and apparently can be used on any turntable so long as it is possible to mount the two speed-sensing devices, one stationary beneath the platter and one on the underside of the platter. I think that's what John is doing. When you use the Eagle with the RoadRunner tach (which isn't required, so far as I can tell), it can feed info back to the Eagle so the Eagle can compensate for speed variation, up or down. My thought was that because the sensing is done only once per revolution, the corrections can only occur once every 1.8 seconds for a 33 rpm LP. This is where I would look for a change in the character of the sound of an idler driven by such a power supply, more than what might be due to watts alone. If I buy an Eagle, I may listen to it for a while as is before setting up the Roadrunner, to find out if I can hear any added or differential effects of the latter.Direct-drives differ from one another as to how speed is sensed and corrected. For example, the Kenwood L07D and the Yamaha GT2000 seem to do it once per revolution, whereas the Denon DP80 has a continuous sensor (and uses an AC synchronous motor, to boot). I am not sure how Technics does it, even though I own one.
Edits: 12/18/16
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