Great post, Henry, and I was not aware of this thread until this moment. As you know, I was one of the many who was and is in disagreement with Raul regarding the necessity for or value of a heavy, dense plinth to go with a DD turntable. But as Pryso says, you have not addressed this issue here. What I would like to know, however, is what IS your Victor tt sitting on or in? Raul makes a point that he uses the rare, and no longer available new, Audio Technica feet under the chassis of his SP10 Mk2. (As an aside, altho Raul evidently did own a Mk3 in olden days, he does not now own one and has not owned one since before he began his and our MM/MI saga. I really defy anyone to use a Mk3 with no plinth at all, because the torque of that motor will rotate the unfettered chassis at every start-up, thanks to Newton's Third Law, and screw up the alignment of all those tonearms you have stuck on outboard arm pods.) I would also like to know what is the make-up of that white shelving upon which you place your gear. Is it possible there is some fortuitously beneficial coupling between the shelf and the un-plinthed Victor? And finally, were you ever at any point able to compare the same tonearm/cartridge combinations on any two of the turntables you tested? By the way, I would rank the Victor as high up among the best of the mid- to upper level Japanese DD's, but like the Denon DP80 and some of the Kenwoods and Sonys, it has not gotten much attention compared to the SP10s. It is not obvious to me that the TT81 would be inferior in any way to an SP10 Mk2. (I would rank the SP10 Mk3 on the highest plain, along with the P3, the L07D, etc. These tables DO kick ass.)
So far, we have you and Albert Porter who have each compared a "good" vintage dd turntable to a current top line belt-drive turntable, with surprising results. I would guess there are others who have done a similar comparison and reached the opposite conclusion, but since they heard what they expected to hear, they have not bothered to comment. As you know, I am firmly in the idler- and direct-drive camp based on my own experiments in my own system, but since I never owned a $10,000 belt-drive in the first place, there is always some residual curiosity. |
Uh-oh. Albert's got one? Is that in fact a photo of Albert's? (Looks like a 12-inch SME mounted in Panzerholz arm board, both favorites of AP, so I guess the answer is "yes".) Nuts! Now I have to ditch my SP10 Mk3.
Janis Joplin, where are you now?
(Channeling her lyric: "Oh Lord, won't you buy me a Mercedes Benz. My friends all got Porsches, I must make a-mends.")
Just kidding. No way I can afford an NVS. But that NVS structure qualifies as a plinth in my little turntable book. |
Dear Raul,
What mat? What tonearm? How was the tonearm mounted? What cartridge? What music?
Let's see: you pulled two turntables out of storage, set them up without a plinth and they sound "great". (I'll take your word for that.) And this proves something about whether or not a plinth can be used to good advantage with a direct-drive turntable? You are too smart to believe that this is good science.
Anyway, very glad to hear from you. As you know, I am very fond of my DP80, as well. On its excellence, we can agree. |
Apologies to Raul, I think I am guilty of asking Raul to prove a negative, which cannot be done. Anyway, more data would be nice. Particularly I would like to know what mat was in use on each turntable (75 vs 80).
So far as I know there is very little if any difference between the DP80 and DP75; I think the DP75 was essentially a DP80 motor supplied with a plinth and tonearm, usually the Denon DA307. T_bone would be the authority on this. If you hear a difference between the two tables, I would first suspect that the inferior sounding one might have a problem. Carry on, Raul. |
Raul,
Yes, i did notice your absence from these fora, and I was hoping that you had not left us and that you were not ill or something bad like that.
Also, I did not think you were not cognizant of the importance of the turntable mat, and it interests me to know that you guys have developed your own. Is it available "to the public"?
I always felt, and said so, that the DP80 gives away nothing to the SP10 Mk2, but to say that it is superior to the SP10 Mk3 means to me only that you need to re-acquire a Mk3 that is in bona fide good electrical condition and listen to it again using your acquired knowledge. Contrary to what you once told me, I hear a big difference between Mk2 and Mk3.
Since you are not shy about stating your negative opinions, please I ask you not to be insulted when I say that marble is not good material for a plinth (don't know about onyx) and that the stock Denon plinth, even the best one that came with my DP80, pales in comparison to slate. The Denon wood plinth imparts a dead/dull sound. (Yes, plinths can do harm,and I am not surprised that naked beats Denon wood plinth.) And I now know that slate can be made better by CLD'ing it with a hardwood base, as I have done for my SP10 Mk3. I am going to do the same for the DP80 plinth. These sentiments are all "IMHO", of course.
The differences between the spec sheets for the DP75 vs DP80 don't mean "spit" (American idiom for "nothing"). I even think the two tt's were measured by Denon back around 1979-1980 when the standards for measurement changed, and all tt's suddenly became 2-3 db quieter, just due to the new method of weighting. Example of that is the Exclusive P3 vs P3a, which looks quieter on paper but was subject to a different method of measurement vs P3. If you hear a diff between those two motors, it is not due to stuff you can find on the spec sheets. |
"What are in common between these TTs other that are TTs: Denon DP-80/75, Garrads, Kenwood Lo70, Technics SP10s, Sota ones, SME 20s, Michel, Roksans, VPIs, Project, Oracle, Exclusive, Linn, etc, etc, ?"
Some sound good. Some sound REALLY good. And some of them are not so good, IMO. But your point is well taken. Drive technology per se is not the sole determinant of what is going to give one pleasure.
Dear Dover, I would not go so far as to say that "wood" (any kind of wood) cannot make for a good plinth. Just that the laminate used by Denon was not so great, although the way they constructed the DK300 plinth was ahead of its time, I think. These days there are some excellent wood plinths being made and sold, by all accounts. I did not mean to start another "plinth war". |
Dear Inshore and Halcro, I dearly love my L07D, and I totally agree with you on the engineering. Those guys were way ahead of their time in designing and building that plinth. And what strikes me about the L07D in action is its inherent dead silence and neutrality and the (for want of a better word) smooth, unintrusive operation of that coreless motor. I even think highly of the tonearm. The only problem with the tonearm is the wiring. I plan to bypass all the internal wiring and the plug at the base of the tonearm, to make a "straight shot" from the cartridge all the way to the phono input. Yet, even with the stock wiring, the Stanton 980LZS on the L07D is a marriage made in audio heaven. |
Hiho, Now take THAT and mount it in a piece of slate or hardwood, and you've got something, IMO. Where are the electronics? Show us what is at the other end of those wires coming off the bottom of the motor. Thx.
You've given me further reason to hang on to my DP80. FWIW, the Technics Mk3 and the L07D are already in this configuration; all electronics are off-board. Steve Dobbins took the Mk3 one more step by eliminating the decorative "chassis" that houses the Mk3 motor and brake system. I don't think that would add much, because the Mk3 chassis is pretty much solid metal. There are no hollow spaces that could ever resonate. What it does do is to get that square escutcheon out of the way which would facilitate mounting of multiple tonearms on board the plinth or use of outboard armpods. I don't quite know how Steve managed to separate motor from chassis; it's not obvious from external inspection how that could be achieved without some cutting. |
Hiho, I have been inside my own Mk3, so I have seen those sights. I looked at a few of the URLs you provided and don't yet see how the Mk3 motor can be parted from the company of its chassis, but perhaps the info is there somewhere. I guarantee I will never do it. Doing it for the DP80 promises greater rewards, because there we do have the issue of a hollow space under and around the motor housing. But re-establishing the tape head reading system is a ticklish business, I would think. I did add damping to the underside of my DP80 chassis, in the form of beeswax melted out from an old KLH9 ESL power supply. There was a definite audible improvement.
I have also seen those websites and deeply regretted that I cannot read Japanese. My son could easily translate, but he hates for me to ask such favors and would therefore take forever to do it. Do you read Japanese? |
I take it that the two URLs you cite above show the top and bottom of the denuded Mk3 chassis. (Well actually I KNOW that the top photo shows the top view of a Mk3 motor cum chassis.) When I look at the two photos, I do not see where the chassis can be separated from the stators of the motor. Probably there is some way to do it and also to remove the bearing housing. Then you must re-seat those two in some sort of structure so that there is a PERFECT concentric relationship retained. (Otherwise, you will have wow problems like none of us could ever imagine.) Also, you must create that structure, which holds everything in this exact proper orientation, so the platter can fit over it. Not a job for Joe Amateur (or Lew Amateur). Steve Dobbins is an experienced machinist, which is how he can get away with explanting those items successfully. Alternative is to get out a saw and just cut away the decorative escutcheon. The Mk2 is a piece of cake by comparison. |
Hiho, I stand corrected. I am not sure the four screws you highlighted are the ones that do the trick. They may just secure the circumferential part of the brake system. However, the other photos clearly prove it can be done. Where the heck did you get these nice photos? I treated my Mk3 like it was inviolate, because it was NOS. I did not give much thought to explanting the motor. It would be very very easy to make a sturdy plinth for the motor alone, based on your photos. IMO, the major gain would be to facilitate the use of more than one tonearm, because the remainder of the chassis is very solid, not likely to be a source of resonance or noise. In stock form, if one wishes to use two tonearms, the secondary one will have to be at least a 10-incher, if not a 12". |
Merry Christmas and Happy Holidays and Happy New Year to you guys, including Henry. |
Henry, You are in Positano? A very attractive women whom I met on a train only two days ago was on her way to JFK airport to catch a flight to.... Positano, Italy. Look for her, very short blond hair cut like a man's, mid-40s, the rest of her definitely does not resemble anything male. Of course, now I remember that there may be a Positano in Australia, given that one of my best friends has a summer home in Sorrento, near Melbourne.
Aigenga, I hate myself for taking the bait, but the fact that an idler drive sounds best in a well-designed plinth does not make it inherently inferior to other drive systems. Other drive systems present different unique issues that also have to be dealt with. Also, what I was trying to say about belt drives, however badly I phrased it, was that many current generation belt drives could be said to follow the no-plinth dictum but in fact they do have very elaborate underpinnings. What has been done away with is the wide open deck surrounding the platter. Losing that deck seems to result in a more open sound, possibly because it reduces direct reflections of sound energy emanating from the stylus/LP interface. (That's completely off the top of my head and possibly complete BS.) I think that's the major benefit of what you guys are doing, getting rid of the open deck. It's what I liked about Nottingham Analog tts. Yet in the last few years, the conventional plinth has reappeared among mainstream (i.e., <$10,000) belt drives. To wit, the VPI Classic, Well Tempered Amadeus, etc. |
"It is now possible for me to design a circular aluminium frame cut and welded out of 10mm thick flats into which I can just 'drop' the Victor."
Be careful, Henry, that's what some of us call "a plinth".
If you want to take the time to describe in greater detail the events surrounding your disaster, perhaps I can help. I have quite a bit of DIY experience. From what you wrote, I don't have a clear idea. Was the Cu180 placed UNDER the TT101 prior to the event? And what exactly was the "event"? A burst of very high level signal is a danger to speakers primarily; I would not expect it to damage a phono stage or other electronic devices. An alternative hypothesis is that something blew in the phono stage, which is what you heard as a burst of loud noise. Nothing to do with acoustic feedback. But I don't know all the facts. |
Question: "I placed the 420STR on the record and hit the 'mute' and that's when an almighty noise erupted." Is this step #5? You just placed the 420STR on the LP and then un-muted?
I presume the tt was activated, platter was turning. Yes?
Can you characterize the crescendo of "noise"? Was it low frequency, high frequency, etc? Was it like what one hears at, say, a rock concert where the sound man is trying to adjust the mike and one can get that obvious microphone feedback between the bass player's speaker and the microphone, a "screech"?
Since your unit is already being repaired, I suppose all this is moot, but it might be a good idea to try to hash it out so the problem does not repeat itself, I guess. |
Henry, I see that you already started a separate thread to discuss the problem. Sorry for asking you to repeat yourself here. I will read what has already been asked and answered on the other thread. Almarg is a very knowledgeable and thoughtful guy, as are others who have responded on the other thread. |
Dear Nicola, I do think there is a qualitative difference between a real plinth (including the 3-legged skeletal one described by Henry) and using just footers of one kind or another under the bottom of the chassis proper (which by the way was never intended to support the weight of the entire object). I guess you know as well that "base" is a synonym for "plinth" in English. |
IMO, the Onedof turntable was designed around a novel idea for a bearing. The designer seems to know very little else about turntable design. Thus I think he is entitled to his opinion but that it is not much more relevant than that of any other moderately knowledgeable person. Sorry.
There are ways to couple the bearing and tonearm effectively. I do agree that the goal is a tricky one. In the process, you probably don't want to introduce tt motor vibrations.
Nicola, I know you are having a good time with your philosophical meanderings, but really, base = plinth, in English. It's that simple. |
Dear Nicola, Freud is widely quoted as having said, "Sometimes a cigar is just a cigar." If he said it, I don't know whether he said it in Viennese or English, but the meaning is left to the knowledgable listener to divine. A person who had no prior experience of Freud would miss the point entirely. Thus, among us guys, "plinth" means the same thing as "base". The argument is whether those footers constitute a legitimate base or plinth. Those 19th and early 20th century philosophes of whom you are so fond should have been watching more television.
Someone in my early and mid-life used to remind me that Socrates was forced to drink Hemlock. |
Aigenga, All this is leading to the revelation that Freud used a direct-drive turntable in a slate plinth. Given my ethnicity, I have/had no problem with the assumption of guilt. |
Dear Aigenga, Your listening is the final arbiter of whether any change is a good one, but I would only observe that by using a "spongy" washer where once was a solid washer, you have to some degree decoupled the motor from the rest of the chassis elements. This obviously can be a good thing. But it can also be a bad thing, because now the motor/bearing/platter as a unit are more free to move when the motor is called upon to increase torque in response to drag on the platter. Remember Newton's Laws of Motion: every action has an equal and opposite reaction. When the motor urges the platter in the clockwise direction, the motor itself has a tendency to move counter-clockwise. Plus, the Victor engineers had the option to anchor the motor assembly in any feasible way, and they chose what they chose. Just a thought.
Irrelevant if you are pleased with your modification. |
Halcro, Yes, that is a plinth. I like the idea of removing the chassis cover below. It looks cool, too. I think this set-up, along with your extraordinary tonearm pods, has the Lew seal of approval all the way. (Your pods are so solid and heavy that I won't carp about them, especially since the materials of the new plinth are similar to the materials of the arm pods.) I've been thinking about something exactly like what you have, EXCEPT I would have a firm linkage from arm pod to main plinth structure, and the arm pod(s) would therefore not have to make contact with the shelf.
I acquired some very heavy thick elastic bands which I was going to use to damp vibrations of the chassis cage that you've entirely removed. The only issue you may encounter might possibly be that the cage shields against RF.
May I suggest that you listen with and then without those rubber isolating grommets? I would be very interested to know what that does.
My TT101 has had a frustrating history. It had to go back to Bill Thalmann twice since the original re-cap was done. There is nothing wrong with any of the ICs, but Bill finally figured out that several of the PCB tracings and a few connectors had developed cracks causing intermittent short circuits, which led to crazy behavior of the mechanism. (It would work properly at Bill's shop for days. Then because the drive to my house is over bumpy roads, I guess, it would do nutty things in my house.) I've now got it home finally and all is well, after Bill sniffed out the problem areas. I do have a bunch of clock chips for anyone who has a Victor TT with a bum clock (Part #SC3042, made by NPC). (The same chip would work for TT81 and 101 and possibly for 71.) Mine never needed it. Contact me privately. They are cheap. |
I only suggest it would be interesting to listen to Halcro's TT101 with vs without the rubber isolators (or whatever they may be made of). Of course, Halcro has to do the dirty work, so it is easy for me to suggest it from 10,000 miles away.
And the reason I bring it up is that Garrard guys remove the stock rubber surround between the 301 chassis and its plinth, whatever the plinth material. They say that the insertion of the rubber between the chassis and the plinth impedes the capacity of the plinth to soak up motor vibrations, and indeed it makes a lot of sense that that would be so. In a DD, any tendency for servo action to cause relative motion of the chassis vs the platter must be countered, so the same principle applies.
Gosh, the TT101 is quite smooth and quiet. Just looking at it in operation, it HAS to sound great. Love those coreless motors. |
I think the word "hooker" comes from the USA. During the Civil War era, (1860s) there were prostitutes that followed the army of General Hooker, an officer of the Northern cause. Somehow, these ladies came to be known as hookers. I wonder whether General Hooker was ever aware of how his name lives on and why. Thus, if the Arabic countries use the word "hooker", I would be surprised and a little sad.
Halcro, I do not think you would hear any noise from the tt due to the lack OR the presence of an RFI shield. If the outer cage is a shield, it may as well be shielding the neighboring equipment from RFI emanating from the TT101 as vice-versa. RFI going in to the TT electronics from an external source might hypothetically affect function, but there would be no noise per se. I really doubt there is anything to worry about. By the way, based on my sample, dust gets in through the slits in the outer cage anyway; dust accumulation may not be any worse without it.
On the issue of rubber or similar isolators, John Nantais, a well known builder mainly of plinths for Lenco, also eschews the use of any such devices and for the reasons I gave above. On the other hand, he is building huge complex plinths specifically to enhance the performance of an idler, which has problems different to those of a DD table. And your "plinth" is minimalist and for a DD that has especially low amounts of motor energy that needs to be dissipated.
The EMT927 has a huge motor, a heavy platter with a high moment of inertia, and a built-in suspension. How does that work? Is the suspension built so as to resist twisting in the horizontal plane? |
Tim, Being a Connecticutian (a term of my own concoction) by birth and still a Connecticut Yankee at heart, I know Willimantic quite well. A prostitute could starve there, unless she also liked to babysit or cut grass.
As it turns out, I am wrong about the association between the word "hooker" and General Fighting Joe Hooker, even though he was notorious for his patronizing of prostitutes. Seems the slang may pre-date the civil war, back to the early 19th century New York or even to England in the 1500s. No one knows for sure.
Halcro, Could you be induced to make me one of those? How much does it weigh? I ask because if I were to modify your design in any way it would only be to maybe add another "ring" so as to enhance mass.
Now, as to the ferrous nature of the outer cage, that is interesting and it suggests to me either that Victor chose it as a matter of convenience or that it was indeed chosen for its shielding effect. Yes, I would like to know Al's opinion also, but being ferrous it would be a shield of sorts. Note that in the owners manual also they make a big point of connecting that ground lug on the outer cage to audio system ground. That WOULD be essential if it is functional as an RFI or EMI shield. How are you grounding the TT101 with no cage? With my balanced Atma-sphere phono stage, tt grounds have always been irrelevant. With my single-ended outboard phono, grounding is critical. |
Nandric, Are the moderators THAT prudish? Shame on them.
Halcro, Good on you that you did not agree with Ct to use compliant footers. We are not so far apart in our thinking.
I discussed with Bill Thalmann your finding that the cage is ferrous and therefore attracted by a magnet. Bill agreed with me that it must be meant as an EMI/RFI shield to protect the outside world from RFI generated from the TT101. (The quartz crystal oscillator is a prime source of RFI. Maybe that's why the clock oscillator is also tucked up into the upper metal structure, away from the rest of the circuitry.) As to the fact that you've observed an effect of the motor on your new steel plinth, I would submit that the ferrous outer cage would also soak up the magnetic lines of force from the motor and also protect the outside world from the magnetics. (But I find it odd that the magnetic effect would be so strong, maybe from the transformer, in some way?) Grounding the cage provides a way to drain RFI to ground, as well as electrical grounding. If you don't ground it, it cannot work so well as a shield. |
Chris, Without getting into the debatable issues, I am trying to figure out how your own description of that SP10 matches with what I think I see in the photo. From the photo, and the two smaller inset photos which I cannot get my computer to enlarge for me, I think I see that the SP10 sits on spikes that are inverted such that their pointy tips are going up into the threaded bolt inserts on the bottom surface of the SP10 escutcheon. I don't see anything "compliant" in that. Then I see also that you are a Copernican; your tonearm is on a heavy brass pod. Is all of the above correct? Just by eyeball, your brass pod appears to be canted with respect to the SP10 platter surface. Probably an optical illusion. |
Aigenga,
In the TT101 Service Manual it explicitly states that the bearing needs no service, which would include periodic lubrication. Bill Thalmann also strongly advised against trying to "lubricate" it. You may fairly respond, and I would agree, that Victor probably did not envision a 30-year lifespan for the product. Therefore, at this point in history, some attention to the bearing may be merited. What did you see when you first accessed the bearing? What was the condition of the lubricant, the bearing, the thrust plate? I am just curious; I don't think what you did was necessarily "wrong" in any way. What lubricant did you use when you serviced your bearing? Thanks.
Halcro,
I think what you have now is a "plinth" by my own definition. Many if not most of the best belt-drive turntables are built with solid, heavy bases that do not afford an open deck surrounding the plane subjacent to the platter; I always thought that was a good idea, as is yours. If I had it to do over, I might have fashioned my own slate and wood plinths in a more minimalist way, but I am not about to do it over. By the way, my Lenco most of all benefits from its dense slate plinth. Why re-open the argument? |
I am all for "education and hobby fun", dagnabbit!
The Denon DP80 bearing is also supposed to be "forever", so I've done nothing to the bearing in my DP80, as well. The fact that your bearing fluid was brown indicates it probably was a good idea to change it. However, I personally would be leery of over- or under-tightening that slot-head screw that forms the seal at the bottom of the bearing well (in the TT101). Anyway, you got away with it. The thrust plate might be teflon, probably not "soft plastic".
Did you mean to imply that you needed to access the innards of the bearing in order to install rubber/steel grommets between the motor and the frame? I am not sure why, if so. |
I agree with all that the metal chassis is a sonic problem and removing it entirely might be a good idea. I am going to try it. I had already come to the conclusion that the "pants" on the DP80 ought also to be removed, but first I am going to try damping the DP80 chassis with two thick strong rubber bands that were gifted to me.
The TI Shield won't do anything down there, especially since it is apparently not grounded. To ground it, just solder a bare wire to it anywhere on its surface and run that wire to tt ground. But in that position, it can't be of much help regardless.
The only downside to de-pants-ing is that it removes the RFI shielding afforded by the ferrous pants. Thus I would be cautious not to interpret changes you may hear in the sound solely to removal of resonances. There could be some RFI contamination via the cartridge. Sometimes any change to the sound that is new is also thought to be good, until you listen for a long while and realize you are fatigued by something irritating in the new sound. I hope this is not an issue, however. |
I guess Syntax might say that he is not surprised that you prefer the TT101 to the Raven for deepest bass response. I've never yet owned a BD tt with a platter that would meet Dertonearm's standard for mass, so I have no opinion (and in fairness, I may be misquoting the minimum mass, but the parameter "35 lbs" sticks in my mind). I did at the time take some issue with his explanation for the finding, which was not solely based on rotational inertia. |
Perhaps a thong. But then one's other turntables would be attracted.
I hope Halcro does not mind this diverting of his thread topic from nude to TT101 nude, but I have a TT101 question for other users: Even after Bill Thalmann blessed mine, I still have the following occasional problem. The TT will start up and go to 33.32. Then after 5-10 seconds, it goes to 33.33. After about a minute or two more, it will go to 33.34. Very shortly thereafter it will shut itself down. The tachometer reading disappears, and the brake effect does not occur. The platter spins freely until it loses momentum. If I manually press the STOP button BEFORE the unpremeditated shutdown, there IS a correct brake effect. I had been thinking that there is a problem with the reverse servo mechanism to explain this, but you guys have me thinking that there may be some inordinate drag on the platter, meaning my bearing may need service. On the other hand, if that were so, I would expect to hear a frictional sound (the table is dead silent) and I would not expect the platter to spin so freely and silently after shutdown. Comments?
I am embarrassed to tell Bill about this glitch, because it worked perfectly in his shop when I picked it up. But of course I will tell him eventually. He is a kind and patient man, moreso than I. |
Banquo, Your idea of the cause of the glitches in my TT101 operation is a good one. When we first got it to run at all, it exhibited all sorts of crazy forms of malfunction, even though every single electrolytic capacitor had been replaced, and Bill eventually tracked it down to bad solder joints or solder tracings, just as you say. He told me he spent a lot of time re-soldering various tracings (for which he did not charge), and his work resulted in what appeared to be complete success, based on how the table worked in his shop. It is quite possible that the mechanical trauma associated with travel from his place to mine (about 20 miles on the DC Beltway, which is not exactly cushion-y) put some stresses on other tracings that are now faulty. Can you be more explicit about what you mean when you say "feed through" tracings? I was thinking that soldering of the wires in one or more of the many multi-prong plugs that interconnect the various PCBs could be the source of the current problem.
Halcro, Of course you have every right to post on the subject of this thread (heh-heh). I personally have no desire to argue further about plinth, no-plinth, or arm pods. This is not because I don't care but rather because I can see now that your rig is very nicely done so as to mitigate any criticism I might have of the concepts. I still think that the basic structure of the L07D, with the rock solid connection between the bearing housing and the tonearm mount, is ideal, whether or not the L07D is top dog in all other ways. And as I've said several times, I do also think that getting rid of the "deck" structure surrounding the platter is beneficial. The more the tt chassis resembles a cylinder with the diameter only slightly greater than that of the platter, the better. This is one way toward good sound, not the only way. Fortunately for us, it is easy to achieve the latter goal with the Victor and Denon DD turntables. |
Ecir and Banquo, Before reading Ecir's post, I was about to say that I looked up the definition of "feed through eyelet" via Google, and to my amazement I found the definition. I had never heard that term before. Ecir, in one of those URLs I do see a number of short posts with wires wound or obviously soldered to them, on the various PCBs. There sure are several of those in the TT101. I will check them. But the formal definition of a "feed through eyelet" is a connector that goes through a PCB, connecting a circuit on one side to a circuit on the back side of the same PCB. Guess I will look for those too. (Or perhaps those posts do connect to tracings on the other side of those PCBs, which would not be visible in the photos.) Thanks to you both. |
Very informative. Thanks again. |
What does the app actually detect, EMI or "magnetic fields"? Those are two different phenomena. I would expect it detects EMI. I don't think this is endemic to every single DD turntable ever made; I would expect it is something to think about on a case by case basis with any particular DD. However, as Banquo mentioned, the L07D cognoscenti recommend implementing a shield between its motor and the platter. It seems to me that Kenwood already did that: the platter "mat" is actually a 5-lb piece of quarter-inch-thick stainless steel, which while not being a perfectly efficient shield, does act as a shield. Nevertheless, I did buy a piece of TI Shield from M Percy. I cut it in the shape of an LP and tucked it in under the stainless steel platter mat, so it does not show. I then was able to imagine that it made an improvement; I don't trust such uncontrolled observations when made by the guy who did the work and spent the money (me), but there you have it. One could do the same or similar for the TT101 or any other DD. A copper platter mat would do some good as an alternative. The SP10 Mk3 has a massive piece of bronze or brass in its surface, which probably affords some shielding. Unfortunately, last time I looked on M Percy's website, there is a notation to the effect that TI Shield is No Longer Available. I don't know whether that means it is out of production or only no longer sold by Percy. He does also sell ERS cloth, which could be made to do the job.
Note that any shield must be grounded to be fully effective. I am assuming that, since the TI Shield on my L07D is fully in contact with both the base platter and the SS mat, and since they are in continuity with the bearing, my shield is grounded. (TI Shield has layers of copper on both sides; it is quite conductive. Be careful.) |
Sounds like I was wrong in assuming the app measure EMI and not magnetic field strength, as "Gauss" is a unit of magnetism (but it might also be a unit of measure for EMI; I need to check). I have no evidence that magnetics is any problem with L07D or SP10 Mk3, the latter of which has a humongous magnet and a very powerful motor. Anything ferrous will block or absorb magnetic forces. When you did your measurements, was the TT101 fully assembled and running? Did you compare with and without the "pants"? Possibly blocking magnetic field from the transformer or motor is the primary or a secondary function of the pants, since we do know they are ferrous. ("Old Ironpants.")
The discussion of the awesome Final Audio tts and their relatives brings to mind another audio conundrum. Does a tt need a massive heavy platter to reproduce extreme low bass? Halcro may have an opinion on this, since he is running his TT101, which has one of the lightest platters I have seen on a TOTL DD tt, vs the Raven tt, which has a typical massive platter associated with the high end belt-drive tts. Henry, do you perceive a difference in bass reproduction between the Raven and the TT101? If so, in favor of which tt? Thanks. |
FWIW, "Gauss" are a unit of magnetism. EMI is measured either in Volts per meter or Watts per meter-squared. |
Halcro, I would not expect copper per se to do much to absorb or block a magnetic field, except by virtue of its thickness which would just physically space the LP and the cartridge that much further away from the source. I am glad to hear your report on the comparison between the TT101 and the Raven. There are many in the audio community who say otherwise, and I never could figure out a scientific basis for their claim, that you need a very massy platter to have good bass reproduction. It seems to me that a combination of torque and well done speed control would be as good. If you will recall, Dertonearm once wrote here that at minimum, a platter MUST weigh 35 lbs for good bass.
Lharasim. Are you certain that copper is not an effective EMI shield? TI Shield, which is a documented effective EMI shield, is composed of three layers: copper/permalloy/copper. True, it does not work unless the copper surface is grounded. Perhaps it is the permalloy layer that does the work. I don't actually know. |
I just went to the URL provided by Aigenga. The photos show exactly what I did, as well, to create an EMI shield for my L07D. However, I never heard any "wum-wum" when the brake activated, either before or after shielding was installed. That site is the one hosted by Howard Stearn, who is an orthopedist by day and an L07D Lover by night. |
Halcro, To reiterate, copper does not shield against magnetism, electro- or other, largely because, as you noted yourself, copper is non-magnetic. Also, electrical insulators that you list are not good insulators against magnetism. Stainless steel can be magnetized because it has a (low) iron content. Alu will be as good as rubber, i.e., not good. Distance from the source and ferrous materials are two ways to reduce the magnetic field.
Chris, I think you answered your own question re the Dynavector, if I understand you correctly. It seems there was no detectable contribution from the magnet at the rear of the DV pivot when your detector was at the headshell. Thus, I would think, there is nothing to worry about (based on the fact that you read the same value of 40-ish when the tonearm is not in the picture). Moreover, the DV magnet is actually two magnets held in place in apposition over the stabilizer blade that is fixed to the moving part of the tonearm. Most of the magnetic lines of force would stay localized to that area because of the interaction between the two apposed stationary magnets and the moving blade that is already deliberately created. Yes, I think DV knew what they were doing, as they have stuck with this basic design for nearly 30 years.
Same goes for the Verdier: it uses two huge magnets of opposite polarity to elevate the platter. The magnetic lines of force are therefore concentrated in that space between the two giant magnets. Stick your detector down there, and see what that does. Also, the thick platter gives distance from any possible problem up on the platter surface. |
Henry, Don't own a Garrard 301. Do own a highly modified Lenco L75. In fact the only parts from a stock Lenco that I use are the motor, the idler arm and wheel, and the platter. Where there is a motor, there is an electromagnetic field. Thus I am sure that one would be detected with a detector in the vicinity of the motor. However, I use the PTP plate, which is 4mm of solid steel between the motor and the underside of the platter. Moreover, there is about 2 to 3 inches of space between the motor and the platter, and the platter itself is heavy aluminum. So, the shielding is at least "pretty good", and the physical distance would help as well. These fields generally fall off in accordance with an inverse square law; the strength is inversely proportional to the square of the distance. In DD's with coreless motors, like the TT101 and the L07D, the potentially radiating elements of the motor are particularly up close to the platter. |
Dover, Funny you say that about "converting" the Verdier to thread drive. Nearly all, if not actually all, the Verdiers I have ever seen have been using thread drive. I actually thought it was "stock". One well known emporium near me that sells Verdier places the motor about 3 feet away from the platter and uses a thread drive. I've often wondered how the heck they can keep the thread from slipping down the smooth sides of the platter.
Richard, You voiced my own thoughts on the pitfall of a coreless motor; the orientation of the magnet and coils is at 90 degrees to that of a conventional motor, and this would result in max field strength in the vertical direction. Plus, the coreless motor is very close to the underside of the platter, much closer to the platter than a conventional motor in a Technics or other similar DD. I've noted that the L07D motor is a completely discrete unit, sealed in a casing shaped like a movie version of a flying saucer. Do you think the casing is made of mu metal or something with similar shielding properties? If so, why do we perceive that adding another shield under the platter mat makes a further improvement? |
By the way, the same might be said of the TT101 motor. It too is completely encased, top and bottom, maybe for the same reason??? |
I'm sure it does; I've never seen the thread slip on any of those. That was part of my point to Dover. I thought also you were going to take issue with his idea that the Verdier needs a "stronger" motor. To my way of thinking, the Verdier is one of those in the "hi mass/lo torque" grouping of belt-drive turntables, a grouping that I regard highly for sonics and which includes the Walker Proscenium. Whatever one might think of the Verdier, I believe it was designed "as a whole", and the use of a relatively weak motor is intentional. (Actually, isn't the Final Audio Parthenon also in this group? Maybe it has a high-torque motor. It sure has a high mass platter.) |
The Verdier is NOT "nude" by the original definition put forth by Halcro after Raul. (Please go back to the beginning of this thread.) Nude means or is a synonym for "no plinth". No plinth means that those who adopted the approach mounted their tt chassis' on "feet", most typically the AT616 feet, with no physical union except gravity between feet and chassis. The Verdier has a plinth of the kind commonly used for many BD turntables, e.g., most of the Nottinghams, the Galibier, Redpoint, Teres group, Simon Yorke, etc, etc. I doubt that the makers of those other BD tt's would call their products nude by that definition. But you can call it what you want; just change the dictionary. |
Yes, if your goal is to grow some beans. |
Dover, Whom are you addressing? If you are addressing me, then I was only referencing the definition of "nude" back to the beginning of this thread, whether you like the idea of nudity or not, in a turntable. Please recall that I was not a proponent of the approach at all, and still I am not. I agree that the definition has blurred in the course of 8 pages of posts.
Over about the last 25 years, a trend in the design of belt-drive turntables developed according to which the platter is mounted on a cylindrical plinth that is of about the same diameter as the platter, such that there is no rectangular "deck" area in the plane of the platter. Rather, the tonearm(s) are mounted outboard via structurally rigid supports that are anchored firmly to the heavy cylindrical plinth structure. It was my empirical observation that this idea is a good one. However, it is far from consonant with the concept of the "nude" turntable, set forth on page 1 of this thread. Actually, you and I do not disagree. I can live without the lectures. Thanks. |
Dover, Did you mean "EMF" or "EMI"? The discussion has gotten a bit confusing with the interchangeable use of the terms "EMI", "magnetism or magnetics", and "electromagnetics". Different manifestations of the same phenomena but with different consequences. I think of "EMF" as "electromotive force" = Volts. Units would not be "Gauss", I don't think.
Of course you would measure no EMI (or EMF) near the chassis of your belt-drive, where the motor is way outboard on the other end of the long belt. That is to be expected. Do you think the magnetic field or the EMI measurable in the vicinity of the platter of some DD turntables is damns them all, as a class? I am not even sure there is any consequence to it, and if there is, many have shown that the fields can be shielded.
Halcro, I have no bone to pick with Syntax, but I agree on the observation that he and a few others who are countrymen to Thomas Woschnick do seem to revile his Raven turntables to an inordinately passionate degree. It seems strange at times. He did not insult the TT101 so much as he did insult the Raven. Did TW kick someone's dog? |
Hi Henry, Did you consider slate, or is it difficult to source slate in Oz? I suppose bronze is even denser than slate, but I think slate competes with granite, for density. This is not to say that I have any way of knowing whether slate is better than granite for this application. |
