....there must be an adjustment to accommodate the precise weight/rotational mass of the platter + mat, to make the STOP button work exactly right. P.22 of the TT-10 Service Manual..... D. Quick stop adjustment:-
* With the turntable mounting two 30 cm LP records rotating at 33 1/3 rpm, depress the stop button, then adjust VR647 until the turntable stops without reverse movement.
* Set the turntable to 45 rpm and mount a 30 cm LP record (approx. 200 gm) then adjust in the same manner using VR646.
* Confirm that the turntable without a record and running at 33 1/3 or 45 rpm is stopped by the quick stop after slight movement forward. So by using any weight of mat desired....one may adjust the Quick Stop mechanism by way of the two variable resistors as Banquo mentioned earlier. This Quick Stop mechanism is independent of the platter speed and servo controls which can be easily verified by checking the speed consistency and accuracy with a variety of mats using the Timeline..... |
Apropos of the recent mention of how the reverse servo works to stop the platter of the TT101, when the "stop" button is engaged, I just noticed that when the platter mat is off the platter, the platter does exhibit a little counter-clockwise movement when stopped. WITH the platter mat in place, the platter comes to a dead stop when stopped. This fits exactly with what someone said above (Thekong, Harold, Halcro???), that there must be an adjustment to accommodate the precise weight/rotational mass of the platter + mat, to make the STOP button work exactly right. Thus I also suspect that if one were to use a mat that is heavier than Victor intended, the platter also would not stop exactly on a dime. This makes me worry/wonder whether the reverse servo would also need adjustment to make it work properly during LP play, in response to stylus drag, etc, with a heavier than OEM mat. I am going to stick with the OEM one for that reason, at least at first. |
Thekong, I have put the question to Bill Thalmann, 3 days ago. When he does respond, I will relay the information. I am pretty sure the SL1600 was a candidate, but let's wait for confirmation. |
However, the same chip was used in the SL1500, 1600, 1700 series, and some of those are so cheap that it is not a problem to buy a whole tt and cannabalize it for that part, in order to keep an SP10 in service. If you need specifics, I can try to find out exactly what models to buy. Lewm, I would be very grateful if you could find out which specific models to buy, thank! |
I believe Lewm is right that there must be a cold solder joint somewhere or a pot that needs lubrication where the wiper has intermittent contact or a crimp connector eroded over the years and lost contact. These kind of things require only the merest movement to knock it out of wack. The ghost is in the detail.
Happy witchhunt!
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Halcro, Luckily for me, I have two systems, one of which is on the same floor as our kitchen, if it should come to that. So push come to shove, I can as well use the TT101 in my "upstairs" listening room. But I really do not think there is anything going on related to the basement environment. I don't know why you are not convinced by my observation that malfunction occurs after the TT101 is physically picked up and moved from one room to another, or shipped, or transported in my car. It's just a fact, one of the only consistent findings. Also, once it is up and running properly, it very consistently runs properly from then on. Which is why the last repair guy never could duplicate the problem. He told me that what he did was to turn it on and leave it on, for a week in his shop. Since the problem only occurs at start-up, and not thereafter if start-up has gone well, it is no wonder he could not reproduce it. One could say he never really tried to reproduce it, since that requires starting and stopping the tt. But he treated me like I was a moron who needed hand-holding, so I am happy to have it back in my possession. (I am not referring to Bill Thalmann, who is a great guy and very attentive.)
No malfunctioning transistors. First, Bill checked them all. Second, a transistor does not give an intermittent failure; it's either good or bad. However, the wiring up to and out from a transistor could certainly be "cracked" or more likely cold-soldered.
Nilsvala, Any SP10 should be reparable, because the only unobtainable part in an SP10 is one single integrated circuit ("chip") that is no longer made. However, the same chip was used in the SL1500, 1600, 1700 series, and some of those are so cheap that it is not a problem to buy a whole tt and cannabalize it for that part, in order to keep an SP10 in service. If you need specifics, I can try to find out exactly what models to buy. Albert Porter has done this several times for himself and his friends. I believe he stockpiled a few extra chips salvaged in that manner. |
Thuchan sends his greetings......
The funny thing was that the Sony PS-X9 was located only 10 miles from where he lives.......so he drove it home very slowly.
He hasn't had time to listen to it as he leaves today for sunny climes..... |
Hllo Halcro
Yes.The Technics sp-10, is so complex that technicans even today¨s not quite shure, whats happend inside. |
Kind of gutsy for HW to point out the problems inherent in belt drive, elsewhere in this blurb, since he has made a living from belt drive heretofore. Yes.....seems kind of strange...? Almost like Linn coming out and saying they've finally seen the light......and it ain't belt-drive?! What is equally amusing to me is the fact that the motor Harry uses in his DD....is the same as that used by Continuum in their Caliburn and Criterium turntables designed over 10 years earlier whilst his 3D printed arm follows the Continuum Cobra and Copperhead initiative again produce 10 years earlier? Methinks Harry has had meaningful conversations with Mark Doehmann...the original design chief at Continuum? Sorry to hear of your continuing hassles with the TT-101..... One suggestion I have (as this intermittent fault will never seem to replicate itself in front of witnesses.....is for you to take the TT-101 downstairs to you listening room and remove the metal protective shroud, plug it in and play it. If it works like it does in the kitchen.......continue on till it misbehaves at which point touch and move all the connecting wiring and see if that affects it? I'm not convinced by your 'movement' theory.....but as the turntable CAN perform properly at various locations for long periods of time......there should be no reason why it can't be made to do so down in your listening room? Alternatively....when the problem presents itself.....follow the 'Troubleshooting' procedures outlined on p.25 of the Service Manual. They are very detailed and clear. From a brief scan of this page related to your problems.....I would bet on one cracked or broken wire or a malfunctioning transistor/s.... Both relatively easy fixes? |
Halcro´s quote from the DirectDrive website, essential reading. Those dinosaur made by Japanese engineers never died, they just fell in sleep... What an interesting thread this is. And a new world that awaits searchers for Analog of today. |
From the site referenced by Halcro:
..."The engineer quickly responded that the motor was the toughest challenge, which led to another series of discussions resulting in the design we see here in the Classic Direct, where the platter is actually the main component in the motor. In this case, the motor in the Classic Direct is an AC motor, which Weisfeld prefers over DC motors. He smiles and says, “An AC motor knows where it is, and a DC motor only knows where it was.”
The secret here is that a three-phase motor is used, eliminating the cogging effect that always plagues direct-drive designs. This uneven power delivery results in a slight unsteadiness to the music at worst and a shrinking soundstage at best. These issues are a thing of the past with the Classic Direct, as my listening quickly reveals."
Two little white lies: (1) Speaking of the new VPI Direct as if the platter being part of the motor was not a property of every direct drive that came before this one, and (2) the statement that a 3-phase motor per se has no cogging issues. It would have been better to stick to actual facts. Kind of gutsy for HW to point out the problems inherent in belt drive, elsewhere in this blurb, since he has made a living from belt drive heretofore. |
Yep, damn him! You can whisper some of the witchcraft his way. Ha!
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Only Thuchan would luck into a PS-X9 in what appears to be mint condition. Damn him!!! (Kidding of course.) |
Surprise, surprise! Thuchan is, his words, "now back to the DD camp." Welcome back! :-) PS, That's one lovely looking Sony PS-X9. . |
Lew.
You may be onto something with the multi-prong plugs. It is likely that the individual male and female pins are crimped. Over time with dissimilar metals, wire and pin, along with a bit of humidity, electrolysis is possible/probable. I have with some gear pulled these connectors apart, cut the wire and soldered it back on to the pin. It is a real PITA since the new connection has to fit back into the plastic holder.
You could of course simply bypass the plugs altogether and solder the pairs.
Good luck with the Witch hunt. |
"Witchcraft", written by Harold Arlen and Johnny Mercer, is absolutely one of my favorite songs from the Great American songbook. But no one is running her fingers through my hair when I contemplate the TT101. Nor does the TT101 give me a "sly come hither stare". Voodoo, maybe. |
Don't deny it. It is witchcraft!
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On the subject of "are we living dangerously", I would like to report to anyone who followed my travail with the TT101 on the "other" thread, where it was OT, that after my TT101 ran reliably for more than a week on our kitchen counter, I decided to spare my wife the sight of it and brought it down to my basement system, where I hope to use it. I plugged it in and turned on the Power, due to my (our?) conviction that keeping it powered on was advisable. I left it alone for about a week, because I was preoccupied with other issues. At that point, I tested the function again, ever the paranoid. Now the TT101 was malfunctioning again exactly as it had been doing previously: It starts up and runs for about 90 seconds. While running it displays speed errors, typically 33.32 or 33.34. Then it shuts itself down with no braking and the platter coasts to a stop. At this point, I have spent several hundred dollars with a machinist making alu parts to beef up the QL10 plinth, based on my previous confidence that the TT101 had healed itself. Out of curiosity, I moved the TT101 back up to our kitchen counter. In that locale, it malfunctioned for a while, just as it had done in the basement. However, within about a half hour, it had "healed" itself again, and now it is working perfectly, every time, on the kitchen counter. I am absolutely sure this problem is due to a poor electrical contact somewhere in the circuit, because the problem is associated with moving the unit around. I do not think this has anything to do with my basement or witchcraft. My plan is to take the top panel off and re-solder every contact on every switch. I am also concerned about the many multi-prong plugs that connect the various circuit boards. I don't know how to disassemble them in order to access the soldered joints within, but any one of them could be a culprit.
Thus I declare that the TT101 is the most "dangerous" vintage Japanese direct-drive tt of them all. I've never had any problems with any of the 5 or 6 others that I have owned that did not respond to the simple expedient of replacing the electrolytic capacitors. |
VPI DIRECTDirect Drive AND MM cartridge........are folks actually listening now.....? |
Lew.
Thought that you may find this amusing. Here on the perimeter of the world we spell gary, grey (Gray even comes up with an auto correct spelling error as I type this)
>>>>>>>>Gray vs. grey
Gray and grey are different spellings of the same word, and both are used throughout the English-speaking world. But gray is more common in American English, while grey is more common in all the other main varieties of English. In the U.K., for instance, grey appears about twenty times for every instance of gray. In the U.S. the ratio is reversed.
Both spellings, which have origins in the Old English grǽg, have existed hundreds of years.1 Grey gained ascendancy in all varieties of English in the early 18th century, but its dominance as the preferred form was checked when American writers adopted gray about a century later. As the Ngram below shows, this change in American English came around 1825. Since then, both forms have remained fairly common throughout the English-speaking world, but the favoring of gray in the U.S. and grey everywhere else has remained consistent.
Some people make their own distinctions between gray and grey. You can find some interesting examples in the comments below. There is nothing wrong with these preferences, but they are not borne out in broader usage. For most people, gray and grey are simply different spellings of the same word.
Both spellings are used for the participles, grayed/greyed and graying/greying, as well as for most of the words and phrases involving gray/grey. For instance, grey area/gray area, referring to an area having characteristics of two extremes, is commonly spelled both ways. So is graybeard/greybeard, referring to an older man with a beard, and gray squirrel/grey squirrel (which refer to closely related types of squirrels on opposite sides of the Atlantic). There are at least a couple of exceptions, though: greyhound, for the breed of dog, always has an e, while grayling, which refers to several types of fish, always has an a.<<<<<<<<<<<<<<<<<< |
Hiho, I do agree with you; no plinth can totally take away the coloration of the Mk2, but a good plinth can take away other colorations and leave one with only that and less of the other. Which is why I think the gray-ness was so evident in my pretty darn good slate plinth. Is it not interesting that when the adjective "gray" (or "grey") is used to describe this coloration, all or most of us who have owned or do own the Mk2 know exactly what the writer is describing? Which is to say that there are subjective judgements with objective truth of a sort. To think that the Krebs mods on the Mk2 are less expensive than the mods to the Mk3, around the cost of a medium price cartridge or vintage Japanese tonearm, makes it indispensible to the Mk2, I think. |
IMO, it is not in the design architecture, it is in the build. The two motors are fundamentally the same design but the MK3 has been fed growth steroids.
Richard what a good analogy. I thought that was what audiophiles want. The bigger the better.
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Hiho
I have a customer who has both a worked MK3 and MK2, giving him a unique perspective.
In his opinion the performance gap between then is reduced, post upgrade.
IMO, it is not in the design architecture, it is in the build. The two motors are fundamentally the same design but the MK3 has been fed growth steroids.
Cheers. |
Let me be clear that I never own an SP10Mk3 so I have no way of knowing whether it exhibits the gray-ish tone in Mk2. All my comments were referring to the Mk2 and the models below it. Just saying...
I have limited experience with Mk3 as my former employer has one and it's wonderful sounding every time I was at his house listening to it and since it's in unfamiliar situation I cannot make any valid judgment but at least it has been a positive experience. Lew's positive take only reinforce the notion.
I am only amused by all the Mk2 plinth making and trying to address something that has little to do with vibration control as if a magic plinth will miraculously fix the inherent design issue of the drive system. I'm sure a good plinth can improve noise level, transparency, etc... but that grayish tone aint gonna go away.
_______
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Lew.
Yes the SP10s are DC motors. Maybe the confusion arose when I said that they are 3 phase. The supply voltage does not swing across zero.
cheers. |
In this discussion of those horrible SP10 Mk2 and Mk3 turntables, let me point out, as I did to Richard privately, that there is a world of difference between Mk2 and Mk3. I think I can say that with some authority, as I have owned both, in similar plinths, serving as signal source for the same system in my home. The Mk3 is worlds better in the area of grayness or "irritation" compared to the Mk2. I could and can happily live with my un-modified Mk3, and I do not hear the problems I associated with the Mk2. With the Mk3, one has a very energetic sound that could be accused of erring on the "clinical" side, whereas I definitely did hear the gray-ish coloration with the Mk2. That said, I am a believer in the Krebs mods; I've just got to get the cash together. Every Mk3 owner who has had the Krebs work done is ecstatic, so far as I can determine. (Do you think I should sell a turntable, maybe?)
Richard, Did you refer to the Technics motors as AC synchronous types? Since the PS puts out pure DC, I assumed they were DC motors. |
Interesting story HiHo...... I agree with you about the sound of violins on a DD. Perhaps even more so than the piano.....the holding and modulation of a single string when bowed, can reveal the truth about accurate and consistent speed control of a turntable. More than with any strobe or even the Timeline.....with a solo violin there is nowhere a mediocre turntable can hide and if you haven't heard one on a great DD.....you may not even realise it? It does seem odd though to cram all the added circuitry of the 101 just for the sake of the readout. And to expect people to pay nearly $1k more for it in 1977. This is a quote from the DirectDrive Website.... At the end of the 70s the japanese audio-industry was in a unique position. They had gained control over the worldwide audio-market, the Yen was cheap and big numbers of well-educated engineers brought one innovation after the other out of their laboratories. The "golden age" of audio had risen - those were exciting times with many new models being developed and announced in regular intervals. At the end of the 70s there really was a sort of race between the mayor-players introducing ever bigger, better and more sophisticated turntables sometimes at very high prices. To understand this you have to know that the Compact-Disc at that time was close before introducing, almost every audiophile had a turntable already so the mid-class market was set. Apart from these reasons the analog flagships of that time were image- and prestige-products of the japanese companies often subzidized by their mass-market brothers.
Machines like the Sony PS-X9, the Trio/Kenwood L07D, the Technics SP-10MkII or the Denon DP-100 were built in a "cost-no-object" attitude that never again arises out of Japan. The best materials, excellent Build-quality, oversizing of all parts and innovative ideas were the characteristical ingredients of the top-decks at that time.
Those machines marked the end of an evolutionary process with non-measurable Wow & Flutter or noise-specifications and they had a sonic quality that even by nowadays standards is state-of-the-art. But 1982 the CD finally arrived and it was the beginning of the end for those machines. All japanese companies concentrated their engineering efforts towards "digital". Production-costs had risen and the Yen was standing higher making export of audio-gear more expensive. This was the time when the cost-cutters arrived and soon dominated the engineers. The analog-battleships developed in the late 70s and early 80s were the first products that were killed by this new ideology. Like Dinosaurs they had become bigger and bigger and now they're end had come. As you might already know, Halcro, the force of the reverse current can be calibrated via adjustment of variable resistors in the circuitry. I didn't know this Banquo...so thanks :-) |
Previously when the 'STOP' button was pressed...the platter instantly stopped due to the reverse current in the drive circuit....and then reverse spun for a second before stopping. This reverse spin was due to my removal of the stock heavy rubber platter mat which I have substituted with the lightweight Victor pigskin. As you might already know, Halcro, the force of the reverse current can be calibrated via adjustment of variable resistors in the circuitry. My tech told me that the adjustment would be a PITA to do because he would need to build something to lift the turntable up a couple feet so he can put his test probes underneath while the table is running. I guess if one wants a perfect table, it might be worth doing. But of course the calibration is tied to a specific weight mat; change the mat and one would need to recalibrate. I left well alone. |
Hiho
I think that the greyness is produced, amongst other things, by errors in the speed sensing mechanism. These are due to the way they are put together which can be corrected. I don't think that "pulse" is the correct term for this phenomenon.
IMO the technics TTs get into trouble because they have so much correction torque available. They can respond faster than most TTs to error signals. Even if these error signals themselves are erroneous.
My treatment method is applicable to any DD TT.
The term " jittery" you use is spot on and is what I use to describe the effect on my krebsupgrade web site.
Once heard it cannot be unheard! |
Thanks for elaborating, Richard. I am learning a lot about motor. Would you say the irritating "greyness" from the Technics is due to this high frequency "pulse" created by the feedback network? Can the remedy be applied to other brands of turntables?
Quite honestly, I don't really care what kind of motor is used in a turntable as long as it does not contribute that negative sound quality you mentioned. That jittery sound once heard is easily recognized but hard to ignore and I've been avoiding it ever since I switched to other smoother sounding tables. I'm glad there are technical people like you out there addressing the issue. It's about time to shut up the DD naysayers! :)
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Hiho
Thank you for your considered response.
Re the contentious subject of cogging.
Coreless motors cog, as accidentally powering up a Goldmund Studio without its platter, clearly demonstrated. ( JVC 4 pole, 2 phase, coreless motor). It was a dumb thing to do, but informative never the less.
The problem that you rightly ascribe to the SP range is not IMO cogging.
It is way too high in frequency to be so. The motors have 15 stator poles, don't know how many mag poles, but some higher number.
Making around the mid 200 HZ of power pulses per revolution. But they are 3 phase motors, each phase separated by 120 degrees. The sinusoid supplied phases slide into each other, improving linearity considerably, so "power pulse" would seem to be the wrong term to use.
The SP10s higher pole and phase count than a number of coreless DD motors, would imply, for a given output torque, lower amplitude but higher frequency cogging.
( The motor only delivers the torque asked of it under the load conditions at that moment in time). If it delivered higher torque than the load demand, the platter would accelerate.
I hear the problem in a standard SP10 in the kHz range. This is a feedback speed sense issue and is not intrinsic in the motors architecture and any cogging that it may produce.
It can be fixed. |
Richardkrebs, I agree with you on many points especially about torque. And I'm glad that you are able to enjoy a modified version of the Technics. I just wanted to add that the higher torque the higher cogging and it's a challenge to increase one without increasing the other. Your unit seems to overcome the sound that includes "a tension, stress if you will, to the presentation and a greyness that over time is downright irritating." Well said! I guess coreless motor offers a good compromise for me. Does that make me belong in the "low responsiveness camp"? Can I bring some Clash records for a spin? :)
I'm sorry that I sounded rather negative on the Technics line. I actually have fond memory of the SP10mk2 and, who knows, might even revisit it one day.
Happy listening!
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Regards, Lewm: Please re-read. Prominent mention of servo systems incorporated in the discussed JVC TTs. Also an acknowledgment that a correction was made to a hurried and unsupported comment. Would you kindly put your dog back under the porch?
Hiho: It's good to see that you actually viewed the Pio. links. The mention of a coreless drive in each of those links relating to the Exclusive series TTs should answer an earlier question. Their inclusion was intentional.
As to the specs given, it would seem likely that both manufacturers measured at least ONE unit that spec'ed as quoted. It would be interesting if anyone could provide contradictory figures.
Ya'll carry on &
Peace. |
Hiho et el
I feel that I need to put my two cents worth in on the subject of cored and cordless motors. Some one has to act as a champion for the Technics line. I should also state that I have a commercial interest in the subject, so feel free to discount entirely what I am about to say....
My take on the subject is not between cordless and cored but high torque relative to the platters moment of inertia and low torque relative to same, coupled with the feedback design.
In other words the motors grip on the platter. It's "responsiveness". The Kenwood and JVCs live in the low responsiveness camp. The technics SP 10 range are firmly in the high responsiveness camp.
The SP 10 range in standard from is noisy, not in the conventional sense but noise which is a function of the music being played. There is also a tension, stress if you will, to the presentation and a greyness that over time is downright irritating.
But these faults are not intrinsic in their design, rather it is in their build. These are two completely different things.
I want drive and punch when I am listening to popular music but I want finesse and nuance when I am listening to my favourite genire, baroque.
I listen to music to connect and feel an emotional response. To feel the joy of discovery when the violinist bends the note just..so.
I want it all.
I could not live with a standard SP10 MK 2 or 3. I don't have to, but I very happily live with my worked SP10 Mk 3.
Cheers. |
Lewm: "The earlier Denons with induction motors: did they employ servo feedback as well? It is hard to imagine how that would work well. Did DP6000 use induction motor?" The one I'm know for sure uses induction motor was a DP-755, an old table without quartz lock that I used to own and saw the gut myself. In the Amp8 website there's no picture of the DP-6000 motor but there's a similar looking DP-3000 that uses an induction motor. I believe all the 4 digit series tables have induction motor and they all use a tapehead reader for servo. The later 2 digit series such as DP-75, DP-80, etc... went back to motor with magnet but retained the tapehead servo system. Halcro: "HiHo, Your interest in the Victor motors seem to have been ignited by your experiences with the TT-71.....is that correct?" Long story. I can say it is one of the tables that got me interested in JVC products and DD genre again. Technics SP10Mk2 was my table for the longest time, over 10 years before the DD revival. Always got laughed at by my audiophile friends for not using an "audiophile approved" table a la Linn. But I ignored the noise. Then there was a period I didn't work so I had all the free time to experiment. For whatever reason I didn't use the SP10 and started exploring belt drive and got into the Empire 208, still an excellent table. I just missed the conciseness of the DD and low noise so I decided to give DD another try. I bought a bunch of DD tables for experiment, TT71 was one of them, also included models from brands like Pioneer, Denon, Kenwood, Sony, Technics, JVC, etc... Up to that point I hadn't encountered any table with coreless motor and then one day I got to listen to a dirt cheap Pioneer PL-300 and it had a smooth quality that reminds me of belt drive so I gutted it out and discovered it had a coreless motor. Ever since I started looking for tables with coreless motor and they always have that smoothness I crave for. There are some non coreless exceptions, of course, such as Sony PS-8750 and Denon DP-60. You can call this smooth quality euphony or distortion or whatever. All I know it has a sound I enjoy -- neutral or not, I couldn't care less. It was then I relistened to the Technics models, SP10Mk2, SP25, SP15, SL12000mk2, SLM3, SLM2, etc.... none satisfied me. (Although the sleeper in Technics is really the SP15.) When I started with the SP10mk2 -- college days? -- I was deeply into punk rock and the bass dynamic and tightness is perfect for that musical genre. Playing The Clash's "Police and Thieves"was great way to show off the Technics. But as my musical taste expanded, it no longer could satisfy me in other music, that often criticized sterile sound is true for me. Technics does not represent the best of DD tables, there are many options. It's unfortunate many people dismissed the DD genre just because they didn't like the Technics without thinking there are at least half dozen worthy brands out there.You just have to be open-minded about it. So, that's the gist of it. - - - - - - - - - - - - - - - - Some of the quoted specs Timeltel provided were from Pioneer P3 and P10 and had nothing to do with JVC. Wrong links! It appears the prose was written using Google Translate program with very awkward phrases. Happy Listening, |
I have more than five times the expense invested in my TT-101 over the TT-81....and would love to say that the performance difference is worth the cost....?
Unfortunately (or fortunately)...that is not the case and I can honestly say that I can hear no differences between them. Thanks for the honesty, Halcro; in the same situation, I probably couldn't bear to write those same sentences. ...according to the JVC flyer that timeltel linked to, there is no "significant difference" between the ql8 and the ql10, except the digital counter. So, you may be on to something in your comparative assessment? It does seem odd though to cram all the added circuitry of the 101 just for the sake of the readout. And to expect people to pay nearly $1k more for it in 1977. That was the going entry fee for digital, I guess. |
Wow! I am overwhelmed. But nowhere in your many quotations do I see the words "eddy current", so is it fair to guess that you agree with me? Also, and I have no dog in this fight, nor is it a fight, I had been led to believe from my own internet reading that the TT81 differs from the TT101 principally in the fact that it does not employ a "bidirectional" servo (Victor's parlance). But I always could be wrong. I believe I got that idea from Vintage Knob. (Where else?) The main reason I targeted the TT101 when I needed another tt like I need another... (name anything useless to have two of), was that coreless motor. I think it is key to what I like about the L07D, wanted to know whether that is a general property of coreless motors or some other magic of the L07D.
The earlier Denons with induction motors: did they employ servo feedback as well? It is hard to imagine how that would work well. Did DP6000 use induction motor? |
Throw away those specs. The real units don't meet them. They are pure craziness. they are about as good as amplifier specs of the day. |
Lewm,
The speed problems on my TT-101 were not caused by the Power Switch.
The Power Switch began playing up (not turning OFF) about 6 months ago....and that's when I discovered the benefits of leaving the Victor 'powered up' 24/7.
Surprisingly....when I began doing that (out of necessity).....the switch began working again but switching it OFF.....produced the fault again.
That's when I wrote about the benefits of 24/7 Power for solid state DD turntables.
My Tech replaced the switch which is activated by a gear drive which advances one click at every press of the POWER switch......however in doing so....a small glitch appeared whereby when the power switch is activated now.....the platter starts spinning immediately whereas previously one needed to press either the 33 or 45 to start the platter.
As I now keep the unit powered 'ON' 24/7....this is not an issue for me.
Another glitch since the repair is the brake function which you mentioned.
Previously when the 'STOP' button was pressed...the platter instantly stopped due to the reverse current in the drive circuit....and then reverse spun for a second before stopping. This reverse spin was due to my removal of the stock heavy rubber platter mat which I have substituted with the lightweight Victor pigskin.
Now however, when the 'STOP' button is pressed.....the platter instantly stops but reverse spins for a few seconds longer than it previously did.
I don't know whether to have this and the Power Switch issue looked into at the end of my 3 month Warranty period?
The reason I finally had to take the TT-101 to the Tech was that the digital speed read-out began indicating widely varying speeds at both 33.33 and 45 rpm.
Since the caps and soldering replacement.....this appears to be solved. |
Regards Lewm:
Retrieved from JVC literature:
Both the TT81 and 101 utilize a servo system operating in both positive and negative directions. A disc with either (dependent on model) 180 or 90 slits is opposed to a circuit board with the corresponding number of printed-coil elements. A phase comparator circuit reconciles the signal from a quartz frequency generator with the one built into the motor.
If my math is correct, for the TT101 at 33.3 RPM, speed is sampled and corrected every 0.003 seconds. This second "negative" servo system is absent in the TT71.
Speed deviation for the 101 & 81 is given as 0.002%
Drift stated as 0.00004%/hr.for the 101 & 81. 0.0002%/hr. for the 71.
From this source:
http://audio-database.com/PIONEER-EXCLUSIVE/player/p3-e.html
"Linear torque scheme of a slotless and a coreless structure by Quartz PLL is adopted as a phone motor and a bearing structure. Furthermore, by the conventional measuring method, the impossible rotation performance of 0.001% of less (---) rotation unevenness 0.003% (WRMS, the FG method) a rotational frequency precision is realized."
http://audio-database.com/PIONEER-EXCLUSIVE/player/p10-e.html
"Rotation unevenness, 0.007% (WRMS, the FG method) 0.015% (WRMS, the Japanese-Industrial-Standard record method)."
http://audio-database.com/PIONEER-EXCLUSIVE/player/pl-70lii-e.html
"Rotational frequency deflection 0.002% or less. Time drift : 0.00008%/h."
Again relating to the OP (and I'd not wish to put it to the test) by all references Pioneer is committed to service components bearing the "eXclusive" badge.
Apparently my "IIRC" function is somewhat out of phase. Apologies were offered in advance. In view of maintaining accurate information your comments are entirely appropriate.
Peace, |
Lewm: "Someone else suggested that Exclusive P3 and P3a did NOT have a coreless motor. My information says they both DID." It does not look like the traditional pancake style coreless motor. Judging by this picture in this webpage, it might be a linear motor, which has magnets on both side of the coils like maglev train, with a cylindrically shaped stator with coreless coils, it might be a coreless motors after all. In that picture, the top motor is just an illustration what a traditional motor looks like and the bottom motor is the EM-03 motor P3 uses. It's a novel way to making the stator much like the ThinGap motor used in the VPI Direct table. Lewm: "Denon tt's were said to have an "induction motor". That would be hard to do with a servo-controlled DD turntable; so far as I know the Denon DP80 has a 3-phase synchronous motor." DP-80 does not use induction motor but earlier models, pre-1975, some models used magnet-less induction motors. Chronology is the key here. _______ |
Dear Timeltel, You wrote, "the 71 lacks the reverse eddy current braking both the 81 and 101 implement in regulating overshoot incurred when correcting for speed". According to everything I have read and observed, that is not correct at least for the TT101. The TT101 is unique among 71, 81, 101, in that it has a reverse servo mechanism to correct for overshoot. Nowhere have I ever seen this described as eddy current based. I have no insight on whether or how the TT81 can slow down its platter. I do know that one sign that my TT101 is running as intended is that when I press the "stop" button, the platter comes to a dead halt. When I was having problems, the platter would stop but then rotate backwards for about half a turn before lazily stopping. This indicated to me that the reverse servo was not working properly.
Someone else suggested that Exclusive P3 and P3a did NOT have a coreless motor. My information says they both DID. (They were not really two different turntables; the way I hear it, there was a change in the way rumble was measured and Pioneer re-named the table from P3 to P3a so they could claim the new re-calculated lower number for rumble was associated with something they actually did to the table to improve it.)
Also, Denon tt's were said to have an "induction motor". That would be hard to do with a servo-controlled DD turntable; so far as I know the Denon DP80 has a 3-phase synchronous motor. |
Halcro, That's great news about your TT101, and it is useful to know yours was malfunctioning due to bad power switch. Can you describe again the symptom that it exhibited before repair? Bill Thalmann often wondered whether the switch on mine was bad as well, and that could account also for the fact that mine would work well off and on, once it had been re-capped and re-soldered. Also, it explains why leaving the Power ON is a form of solution to the problem short of replacing the switch. Where did he get a replacement switch; perhaps you can ask him what he used, just in case any of the rest of us has issues.
By Sunday, I will have completed my mods to the stock QL10 plinth. They are anti-Copernican. I will post photos, and best of all I will finally get to listen to a TT101. |
04-04-14: Banquo363:
"The english flyer for the jvc ql8 has a small black and white pic of the tt81 motor. Take a look and see if you can tell whether it's a coreless motor or not." Good find! TT-81 motor - & - TT-71 motorYep, just as I suspected. The TT-81 motor is indeed a core motor, same structure as the TT-71 motor. Notice the coils wrapping around an iron core? You just save Halcro the hassle of taking apart his TT-81. :) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Timeltel, I like your tinkerer's spirit. :) ______ |
Regards, Hiho: A TT71? Guilty. Picked up for little more than pocket change several years ago just to fiddle around with. A hard maple plinth & EPA-250 tonearm. Swapped around some mats (the OEM mat is terrible) & ended up with a Boston Audio Mat2. The basket shrouding the electronics rings, so strapped a couple of bungee cords around it. Cyro'd bungees are in short supply, used what was available. Bluejeans brand entry-level low capacitance cables & some Isonoe feet at the corners. Pulled the Pio. Exclusive PL-70L 11 & then sat for a semi-serious listen.
The little 71 lacks the ability to capture micro detail but is engaging and involving, I like your reference to flavors and colors :). You mentioned Raul; the gentleman also sampled the TT71 and actually praised it, I believe he used it "nude".
No Timeline available but out of curiosity the 71 was timed for eighteen minutes. From a cold start it immediately advanced a nominal four degrees and then remained spot on for the remainder. It's been a while since researching but IIRC the 71 lacks the reverse eddy current braking both the 81 and 101 implement in regulating overshoot incurred when correcting for speed. Other than the coreless motor, the only other difference for the 81/101 is the readout for the 101 is digital, the 81 is equipped with a strobe.
Just an enthusiast, I find critical listening a distraction. I've not read a negative comment concerning either the TT81 or 101, JVC seems to have gotten the series right. Of this I am certain, in spite of, or perhaps because of, the resonant character of the modest 71 it is somehow a captivating performer. Some day I'll return to the PL-70L 11 with it's "stable hanging rotor" drive and exquisitely engineered PA-70 tonearm and then experience a revelation as to what I've been missing.
In reference to Halcro's OP, among others I've a Tech. SP-15 which I expect to someday start spinning like a gyroscope and a Denon DP-60L (a carnival of resonances) with it's fragile magnetic tape attached to the platter.
Pardon the lack of references, corrections to any of the above are welcome.
Peace, |
04-04-14: Halcro:
"If the TT-71 and TT-81 motors are the same......why have the two models?" While I cannot confirm they are the same -- the motors have different model numbers but, I believe, have similar structure -- there's really nothing unusual about using the same motor in different models. JVC and others are giant corporations and they don't think like audiophiles. It was very common to use similar parts with different features. Sometimes with improved electronics they implemented into older models with added features to come up with a new model. That happens all the time in their integrated tables and I can think of at least 5 or 6 models share the same motor. The JVC QL-Y66F has the same motor and electronics as QL-A70, except one has automatic tonearm and the other with manual tonearm. Just look at Technics, the SL-1200Mk2 architecture had been used in 6 or 7 models with various features such as tonearm, plinth, suspension, automation, pitch control, etc.... The best view of the motor is actually from the top, remove the platter and motor cover and you can get a glimpse of the motor structure. Judging by the provided photos, the motor is canister type so it's very likely a variation of the TT71 motor which is a core motor. Please continue to provide us motor porn though. :-) At the end of the day, what matters is that you like the sound of the TT81 regardless of motor type. But the TT71, while decent, makes me desire more so I moved on to their integrated tables, which are sleepers but usually audiophiles are annoyed by their automatic tonearms. If many of these quality integrated tables have an armless version, history would have been rewritten. (If Lenco had more armless L75 models, audiophiles would not ignore them for so long. I know they do have the G-88 but...) The TT81 has advanced electronics so that might have pushed the performance to another level, evidenced by your approval. My own observation so far is that I tend to prefer tables with coreless motor, they pass the solo violin test, exceptions are ones with magnet-less motors as found in Denon induction motor a la DP-60 or Sony PS-8750 or older Sony drag-cup motors with a copper rotor. Aside from top of the line models, many DD tables with traditional core motors as found in models by Technics, Pioneer, Kenwood, etc... do not float my boat. Of course, the motor is just one part of the turntable but in a DD system it's a major contributor to the sound. One can easily argue that the weaker torque of a coreless motor has a less dynamic sound and less drive or "jump" factor in character. So at the end of the day, find what you like is what matters. Audio is like food for me, I'm all about flavors and colors. Lamb chop is great but on some days I just want a salad. That's why we have multiple turntables! I'm sure someone (Raul?) will jump at me about neutrality, faithful to the source, bla bla blah... ______ |
Hello Halcro,
I own 2 of the TT-81's. One is in storage sitting on the shelf. It has been completely rebuilt (including all caps.)
Your comment about it "must be the bargain of the century" is something I have to agree with. I also own a VPI Aries Extended with all mods. I prefer the TT-81!
Regards'
Don |
Hearing back from Antonis about his TT-81 plinth......I was wrong about the granite slabs I thought he used....... Instead of granite slabs.....he has designed and constructed some exotic stressed skin panels utilising bauxite balls and epoxy sandwiched between two sheets of aluminium. You can see it all here Who needs (new) turntable manufacturers when we have inventive and knowledgeable audiophiles able to utilise the best DD turntables ever made? |
HiHo,
Your interest in the Victor motors seem to have been ignited by your experiences with the TT-71.....is that correct?
Your research, photos and Links are certainly invaluable to this Data Base.
I haven't heard a TT-71...but I know the Professor (Timeltel) has one and is quite pleased......
I have more than five times the expense invested in my TT-101 over the TT-81....and would love to say that the performance difference is worth the cost....?
Unfortunately (or fortunately)...that is not the case and I can honestly say that I can hear no differences between them.
But is that really so strange?
Apart from the added complexity of the electronics and the coreless motor.....the rest of the architecture of the two TTs are identical.
Same platter....same materials...same dimensions and structure and same quality of electronic parts.
As you can see from the Timeline videos of the two TTs.....their speed accuracies and consistencies are identical....so why wouldn't they sound the same?
As they are the best sounding turntables I have heard in 40 years.....the TT-81 must be the bargain of the century? :-) |
Regards. Hiho is correct. For a description of JVC technology in the above TTs:
http://www.vinylengine.com/library/jvc/turntable-technology.shtml
A later catalogue states ALL TTs are equipped with coreless motors.
Peace, |
