Dear Henry,
Most of the contents of the long passage you quoted are utter hogwash. (1) Because the TT101 looks complex to the uneducated, like you and me, is no reason to believe it cannot be worked on by a trained professional. It is not voodoo. (2) The very same chip for the SP10s is also used in a wide variety of later production versions of the Technics SL tt's, e.g., SL1500, SL1600, etc. There are thousands of those tt's around,and one can buy them cheaply, if one really needs the chip for one's much more valuable SP10. A certain SP10 aficionado from Texas has done that more than once. Moreover, if you renew the electrolytic capacitors in your SP10 before the chip gets blown, the problem will not arise. (3) I have a Denon DP80 that came to me with a partially defective IC. I was told the part was unobtainium, as you suggest. I took the part number off the chip and did a Google search. I found at least a dozen small electronics houses mostly in Hong Kong that had a supply of the needed Denon chip. (Mind you, this chip was made only up to 1983 and only for the Denon tts, so my results were quite amazing.) I acquired not only an NOS chip for my tt but two extra ones, for less than $25, and there were offers to sell that went as low as a couple of bucks. (I actually paid too much but went with the guy who wrote the most coherent English.) It seems there are thousands of those chips out there. The only problem is that those few who need them don't know how to find them or don't try because they believe they will be unsuccessful. (4) In general, in many cases where discrete transistor parts are no longer available it is because the part has been replaced by one that is functionally superior. Bill Thalmann (one of those "trained professionals") also replaced all the transistors in my DP80, not because any were bad but because Bill knew that the newer part was superior and more reliable and would improve the function of the tt.
So, don't panic or cause the rest of us to panic. You know what is really unobtainium?.... a 1957 Ferrari Testa Rossa.
By the way, I will gladly take a TT101 off anyone's hands, to allay fears that it will fail and can't be fixed. |
Dear Nandric, I read a little about the new data that call into question the actual speed of light. Compared to other previously existing data that confirm the Theory of Special Relativity, I think the data from CERN are rather weaker. I am going with Albert on this one. |
Hiho, FWIW, that's the first thing I noticed once I got my L07D up and running, an uncanny sense of "fluidity" (good word for what I hear), plus the L07D's signal to noise ratio seems to be unusually low, which adds to that same sense. The turntable gets out of the way, and the music is just "there". |
Dear Banquo, What I did point out is that the service manual of the TT101 is available on Vinyl Engine. With the service manual, a competent person can trace a problem to its source. That is the first step in the repair process. As to its possibly unobtainable chips, I would bet that like the ones we know about (Technics and Denon), Victor also used a family of parts that is common to several of their designs in that lineage. It might be a little more difficult to obtain the donor tt, for the Victor family, since so few of the best ones were exported, but it could be done, I would be bet. And then too we have the internet as an unprecedented way to find odd parts that our local distributor might say is "unobtainable". I would not be the least bit afraid to own a TT101, except I would prefer a TT801. Isn't that the very top of the line? Or is the TT101 uber?
Yes, after listening to my L07D, I suspect there is magic in coreless motors. Note that Brinkmann has chosen to use a coreless motor in its direct drive renaissance. But one can hardly make a firm conclusion based on one sampling, and I am sure motors with an iron core can sound great to. To wit, the SP10 Mk3. I have no idea about the NVS motor type or its speed control mechanism, except I think I read that they have eschewed the use of a servo. |
PS. Yes, coreless = slotless. Just found a site that confirmed my impression. And coreless motors do not exhibit cogging. |
A belated response to Henry's question about the complexity of the SP10 Mk3 vs the TT101: There are no on-board electronics in the Mk3 save for the on/off and speed selector switches and wiring thereto and the brake solenoid. All the electronics are housed in the outboard power supply, which is much larger and heavier than that of an SP10 Mk2, for that reason. This arrangement allowed Technics to build the chassis proper such that resonances are minimized. (No hollow cavity or thin-walled structures, etc) And I reckon it also allowed more room on board for the humongous motor. As to what's inside the Mk3 power supply, I deemed it to be so "special" that I did not want to mess around inside it. (As you may know, my Mk3 was acquired in NOS condition.) I simply handed it to Bill Thalmann and let him do the work. Ergo, I don't know what it looks like inside. But the schematic is available on VE. |
Henry, On that last post, one would have to peer into the brain of a Victor engineer to find out why all Victor tts were not equipped with coreless motors. The motor in the TT101 is not only coreless vs the TT81, it also has considerably higher torque, I believe. Those two characteristics definitely would add to the cost of producing the motors, for sure. It is more costly to make a high-torque coreless motor than a cored motor of similar torque characteristics. Also, coreless motors are more prone to overheating under stress, so that had to be considered in their design. And finally, what was the actual price difference between TT81 and TT101?
I know for Kenwood, their KD500 (I think that's the model), which was one very giant step down from the L07D in all other ways, nevertheless also came with a coreless motor. Pioneer used coreless motors in their Exclusive line of tt's; do the upper end of the Pioneer line tt's also have coreless motors? Don't know. Technics seems not to have used coreless motors at all, but as you pointed out, their best motors have 24 poles and the DC power supply could further reduce cogging to a non-issue. Motors and their power supplies are an art form unto themselves. |
Hiho, In some magazine or on the internet, I saw a photo of the Bardo motor with its coils exposed. It is striking how much the whole construction resembles either one of the L07D motors you showed in your photos. Makes you wonder whether Brinkmann intentionally took a page from that book.
Reference to "12 pole" in the description of the Monaco motor should tell us that it is a 12-pole motor, not coreless, if I my understanding of the jargon is correct. But I read in one of the original reviews that the motor is a very advanced modern space age design specifically aimed at eliminating cogging. I also read on the NVS website that they have eschewed the use of a servo system; I hope I am re-stating it correctly, but as I recall they make the motor operate against a specified drag, in order to keep speed stable. Much like the eddy current brake used in the Garrard 301/401.
On Technics. My early impression of my SP10 Mk3 suggests it lives up to the hype.
Has anyone here (hello, Shane) been listening to an Exclusive P3? I'd like to get a better feel for that thing. |
Far as I know, the motor with the symmetrically arranged coils is indicative of a second generation L07D. There are photos of such a tt on the LO7D website hosted by Howard Stern, who serviced both of my L07Ds. But in real life, I have never seen a second generation LO7D for sale or known one to be in the hands of an end-user. (It differs from the first generation type in other ways besides the motor structure; the tonearm rest and the adjustable support feet were also built differently, and there may be some differences in the electronics, or not.) I suppose if you canvas the LO7D email group, you might find one. Last year there might have been one for sale on the Hifido website. Which is a long-winded way of saying that my L07D(s) (both of them) are the much more common first generation type with the assymetrical coils. There has to be a reason why Kenwood chose to build it that way, but I cannot imagine it. Do you think it was to avoid infringing on Dual's patent? Note that the Bardo coils are not symmetrically placed around the spindle, either. |
Way cool! Did not know about the Dual. Perhaps I should have gone to R�MAF after all to hunt down each of the modern DD's that we know so little about.
I take it you were dissatisfied with your Mk2 on other grounds besides "bass dynamics and tightness", One big diff between my Mk2 and Mk3 is that I made a better more sophisticated plinth for the Mk3. The Mk2 was all slate. The Mk3 plinth is equal parts slate and cherry wood and weighs around 90 lbs. I found that the addition of the stiff hardwood dampens the slate, whereas the slate is very good for channeling energy away from the Mk3 chassis. Anyway, the Mk3 plinth is very neutral. The Mk3 itself imparts a little more energy than the Mk2 and has very low coloration, if any. However, I thought the Mk2 in slate was very fine and could have lived with it. I firmly believe there is such a thing as "good enough". After good enough, the rest is a hobby. |
Hiho, His second post was in response to something I must have written, since he is addressing me. Yet I have no recollection of ever reading this treatise before. Also, he talks about "poles" in coreless motors, so this means I am full of baloney (to put it nicely) when I said that the Teres (was it?) motor cannot be coreless if it has "12 poles". I have to do more reading on this subject because obviously I am not qualified to have any opinion. Now, where can I buy a Dual 5000CS? That would be a great motor for my Lenco. |
Avid. That's the name I was trying to think of. Nice stuff. Light-ish platters/high torque motors. |
A vibratory hum from the transformer is nothing to worry about, as long as it does not intrude on the listening experience. If you had an amplified hum coming thru the speakers, that is another story, but don't worry about the local mechanical hum. Why yours hums and Henry's does not is possibly only a function of the voltage and/or frequency of the current coming from your wall socket vs Henry's. (Don't know the voltage/frequency in Australia.)
Henry, are you using that stethoscope to identify nodes in your shelf? As a doctor, of course I was born with a stethoscope around my neck, and even though I never use one in my chosen field, I have always owned one or two. |
Yes, the direct-drive school does seem to have two camps, high torque motor/light platter vs low torque motor/heavy platter. And yes I think the LO7D is more in the latter camp, certainly compared to Technics stuff. There is an analogy in belt drive turntables too. Notts and Walker (to name two of many) favor weak motor/gigantic platter. SME and (argghh I can't remember the name, begins with an "A") would be in the light platter/powerful motor school.
The only guy I know for sure who would understand this stuff and could explain it to us is Mark Kelly, but he is preoccupied with other things at the mo'. |
Mind you, the Littman was preferred by cardiologists, not audiophiles. As I recall, it was quite good for picking up murmurs. But another virtue if you are schlepping it around a hospital all day is that it is very small and light compared to some others that have complex and heavy bells. (The bell is the business end of the scope.) |
Where to begin?
Dear Gary, Henry makes a VERY good point; if you have plugged your TT101 into the 120V wall outlet, that could very well be what is making your transformer hum. Even though the voltage is only slightly different from 100V, you had best use a step-down transformer. You may eventually damge the TT101, otherwise. They are available on eBay. You only need one that can handle 50W or slightly less.
BUT I am not clear on what you are hearing. In your last post it sounds like you may indeed be hearing hum through your speakers. If so, this is unlikely to be due to the power transformer. Look for another cause. As for EMF, the transformer and turntable motor are emitting EMF no matter whether they are noisy or not. I use a shield on my (coreless) LO7D motor (between the platter and the platter mat, made out of TI Shield available from Michael Percy). There never was any hum problem with LO7D; the shield reduces or removes a kind of gray-ish glare that colored the L07D output. TI Shield blocks both EMI and RFI. If you are hearing only a local mechanical hum directly from the tt, then go back to my first paragraph. If you are already using 100V step-down, then you just have one of those transformers that hums. Try reversing AC polarity; sometimes that helps.
Dear Henry, Of course you have to tap the shelf!!! The node will be at the same place regardless of how you stimulate the shelf to vibrate, so the result achieved by tapping and listening with the stethoscope is always valid. However, I do not think this has much if anything to do with airborne vibrations. This has to do with structure borne vibrations emanating from your environment. Even a wall is not inert, as you know better than I do. Plus there is the issue of micro-seismic activity. And your huge feet clumping around the room as you dance to the music.
When I was a medical student, everyone wanted a Littman stethoscope. But there is at least one other very good brand. I have not only two of my own but the one that belonged to my father, from before WWII. A�nd my wife would lend me hers in a pinch. (That is, if I pinched her.) |
Gary AND I should have written "EMI", not "EMF". EMF stands for ElectroMotive Force, which is another term for voltage. EMI stands for ElectroMagnetic Interference, which is undesired low frequency radiation from a transformer or motor. I picked up on Gary's error in my response. |
I finally do understand why you are concerned about the mechanical vibration of your transformer. A good platter mat can isolate the LP from such low level disturbance. Also, sometimes you can make mechanical transformer hum go away by judicious tightening of the bolts that hold the transformer laminations in place. You have to do this very carefully (don't just crank down on them with all your might) and symmetrically (tighten all of the usual four bolts a little at a time and see at each step whether the hum is reduced or finally gone).
Can you hear the hum with the bell of your stethoscope placed against the platter mat, where the LP sits? If not, no worries. |
A little stethoscope is a dangerous thing, because it imparts a little knowledge. |
My profound apologies.
That blather about thimerosal was in response to a post on another thread. As the late great Gilda Radnor might have said in the guise of her TV character, Emily LaTella, "Never mind." |
If you do it yourself, which I endorse also, it is worthwhile to invest in a "solder station". This is essentially a soldering iron with feedback, so it maintains a constant temperature, which you can set on a dial control. They cost more like $50 to $100 but a good one lasts forever and you can use it for other minor repairs in future.
Was the "reputable tech" named Bill Thalmann? If so, Bill would do much more than just R&R the caps, which is probably why his estimate seemed high, if it was Bill (but you already told us that Bill declined the job, so maybe not Bill). |
Banquo, If, God forbid, you ever do have a problem with the quartz clock or any other unobtainium ICs that may be lurking in the circuit, you are not necessarily out of luck. If Victor was anything like Technics, you will find that some of the individual parts of this type were also used in lesser models, often available at much lower cost vs the TT101. Thus you can probably find a lower level Victor to use as a parts mule for your TT101, if push comes to shove.
Henry, This time I emphatically agree with you; someone got a steal on that TT101. |
Dear Banquo, Based on your recent experience, it is possible that you have not yet fried irreplaceable parts or circuitry that is inscrutable to even Bill Thalmann. So it could not hurt and might help a lot if you just have someone remove and replace ALL the electrolytic capacitors. Bill is probably tired of spending most of his time repairing direct-drive turntables. If you can dig up a schematic or a service manual, you might eventually arouse his interest. You might try a Japanese source. But meantime, my advice is do the lytic caps; it is probably necessary and certainly cannot hurt. The parts cost will be well under $50.
Even Howard Stearn, the guy who runs the L07D website, has given up on repairing and restoring L07D's. I think my second one was the last that he was willing to do. He's an orthopedic surgeon by day, so one wonders why he ever got into it in the first place. There's more money in hip replacements. |
Let's say, at most he needs 3 hours. (I am fairly sure I could do it myself in less than 3 hours, and I know good techs are faster, neater, and better than I.) Let's say he charges $80 per hour. (I have no idea what they charge these days.) The capacitors might cost $30-$40, if that much. So you are talking around $300 for peace of mind and probably improved performance. One of those "no-brainers". |
Cat9, Capacitors are cheap, available, and better than ever. That's why I repeat ad nauseam that one ought to routinely replace electrolytic capacitors in the circuits of these old DD turntables, because failure of one of them can lead to destruction of a "microprocessor" that might be unobtainium. (In fact, your DP45 probably has only one IC, at most, but it controls major aspects of tt function. I found 3-4 years ago that it was not unobtainable, if one does a parts search on Google. I don't know whether it's still buy-able.) There are several discrete transistors in the Denon DD turntable circuits; all of those are either available or replaced by better versions. You will have no problems replacing the discrete transistors, if needed. It's that single IC you need to worry about. |
I've got two spares for my Denon DP80, but I believe it is not the same IC as what was used in most of the other models. If the caps are kept tip-top, and if one does not plug a 100V Denon into a 115V AC outlet, all should be well. (I am pretty sure someone who owned it before me blew the IC in my DP80 by doing that. Or, as he told me, "we always plugged it into the wall directly with no problems". This means that since the turntable continued to rotate, there could not be a problem. No matter that it was off speed and that the strobe light no longer functioned as a strobe.) |
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. |
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? |
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. |
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. |
Only Thuchan would luck into a PS-X9 in what appears to be mint condition. Damn him!!! (Kidding of course.) |
"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. |
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. |
I wonder how a perimeter ring could fit. The lip of the platter does not rise much above the surround. It looks cool that way but not very accommodating for a perimeter ring weight. Aigenga, Can you post a photo? Thanks.
I pretty near finished up my mods to the QL10 plinth last night. So, at last, I may actually hear a TT101 as Victor intended it, with a Victor UA 9-inch tonearm in the QL10 plinth. I will try to post a photo of the whole enchilada.
I also made, or had a machinist make, two extra alu armboards probably to be used for FR64S, Grace G714 (the wood version), or Dynavector DV501. |
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. |
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. |
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. |
Halcro, I think the important point you made by quoting the manual is that my concerns about a heavy mat upsetting the servo are unfounded, up to a point, I am sure. There will be some weight of mat that screws things up, but you can probably get away with heavier than OEM ones. Thanks. |
Thanks, Gary. So, basically because your mat is thicker than OEM, the peripheral ring works fine. I looked at your other photos, too. Under the platter I see first what looks like a EMI shield, a brushed silver metallic looking insert that covers everything. What is it made of? Then in some other photos, the brushed silver covering is not present, but instead the parts underneath appear wrapped in some black quilted looking material. What's that?
I have a shield between motor and platter on my L07D. Had not considered doing it also for the TT101, but I suppose it makes as much sense. |
Halcro, I would like to post those photos of my QL10 plinth here. Does that require first posting them somewhere on the internet, like Photobucket or Google photos? Or can I post them from my computer desktop? Thanks. It seems that I need to put them up on the internet first. |
Gary, I found on that thread or another DD-related thread that I first wrote about shielding the motor in my L07D, and you asked ME questions at that time. So I assume you proceeded from there, but to find out what exactly I am looking at in your photos, I will seek out the posts you cite. Sadly, the product "TI Shield" seems no longer to be available. One might use mu metal or ERS cloth or just a sheet of copper or stainless or etc. Each has slightly different properties as a shield. |
As Halcro and I know, there is NOTHING in turntable land quite as complex as a Victor TT101. I haven't seen a P3, but the Denon DP80, Kenwood L07D, Technics SP10 Mk2 and Mk3 are as simple as a belt-drive, by comparison to the TT101. |
This guy Chris must be a gem, for sure. And by all means, Downunder, DO replace all the electrolytics in your P3. Like Albert says, you may save yourself a much thornier dilemma at some point in the future, if leaky caps eventually kill off an unobtainable IC. (But maybe there are no ICs in a P3 to worry about.) Now, onto the subject of "IC"s. It seems to me that they are not all created equal. There are some enormously complex and highly specific ICs at work in both DD turntables and in CDPs. Some of them have 16 to 24 "legs", and there are not even solder guns available to remove them from a PCB. That's why the common mode of repair is to throw the whole PCB away and replace it with a new one. Then there are ICs that self-contain a very simple circuit; I have to assume it was one of that type that Chris was able to replicate. |
Fleib, another such arm that preceded the Rigid Float is the RS Labs RS-A1. As you say, it uses "under-hang" and thus achieves tangency at one point on the LP surface. Both of these arms are in the realm of the crazy, but I can say that the RS-A1 really works and sounds way better than I would have guessed. Thus I am curious about the Rigid Float. What bothers me about it is the question of whether the pivot is really held "Rigid" by the floating bearing arrangement. I don't see how it could be. The instructions that come with the RS-A1 suggest 21 mm of underhang is optimal (stylus hits the LP 21mm short of reaching the spindle) but this is more a suggestion than a rule.
Halcro, I agree that a 20-inch arm with a straight head shell would have very little tracking error because of its sheer length, and the skating force would be weaker than in most cases. But the trade-off is the potential for lack of rigidity of an arm that long, plus high effective mass. Interesting for sure, nevertheless. |
Peter, THAT is so cool I am going to ask PBN if they can mount my DP80 in their plinth. A two-armed version would do nicely. |
Doron, I agree with the others, it's probably best not to run the motor without the platter installed. It's definitely taboo for nearly all other DD turntables, for sure. However, I faintly remember that Bill Thalmann told me that where the TT101 is concerned, you can get away with it, because of how the circuit works. Even with that small qualifier, why worry about platter-less operation, if your TT101 works fine with the platter installed? If you follow Banquo's advice on how to raise up your platter by a few mm, via adjusting that screw below the bearing housing, you should be able to cure the scraping problem as well. Now, replace all electrolytic capacitors. |
Fleib, On 8/29 or thereabouts you wrote, "Lew,
You mean 21mm short of the lead-out groove, which would be about 80mm from the spindle?" Then Hi-ho made some further comments to indicate that 76mm is correct.
But if you guys will look at the diagram in the article quoted by Hiho, follow the arc formed by the dotted line. In order to achieve zero tracking error (stylus tangent to groove) at point B, as defined by the designer of the RS-A1 in that diagram, the stylus needs to hit the label or the run-out grooves of the LP where that arc comes closest to the spindle, which I think is indeed about 21mm from the spindle. Thus we were talking about two different things, in one case how to mount the arm, in the other case, where on the LP playing surface we wish to achieve the one point of zero tracking error.
As to the Rigid Float. All that babble about how the "bearing" is constructed does not allow me to form a picture in my mind of how it works, how something can be both "rigid" and "floating". I would need to play with one to convince myself. Well Tempered liked to sell the idea that their tonearms have no bearing and hence no bearing friction; the problem is that their bearing (which IS a bearing, semantics notwithstanding) has a fair amount of play and so low friction is achieved at the expense of wobble. |
Fleib, I fear we are still on different pages. I am talking about how to mount an RS-A1. To do so, you aim it at the spindle and let the stylus fall about 21mm short of reaching the spindle. It is my belief that thus you will obtain tangency somewhere near the middle of the playing surface, or wherever you prefer by adjusting the stylus underhang (i.e., the stylus hits the label a little closer than 21mm from the spindle or a little farther away, whatever suits you). If you look again at the diagram in Hiho's reference, see the arc that is shown as a dotted line. See that achieving tangency at point B will require you to adjust underhang such that the stylus falls on that dotted line arc some distance from the spindle, which I take to be about 21mm, from my memory of the RS-A1 instruction manual.
Doren, For caps in the circuit, I would not stray from the original values given in the parts manual available on Vinyl Engine. Voltage rating can be higher than original but not lower. For caps in the PS, you may wish to use slightly higher values of capacitance, but there is no need for it. Yes, replace all. Any one of them can fail any time, after 30 years. Digikey and Mouser are good sources for Panasonic, Nichicon, and other top quality brands. For only a few bucks you can buy them all. |
Fleib, RS-A1 is also surface mount with no fasteners to the TT plinth surface. Thus you can (all too easily) move it back and forth with respect to the spindle, if you want to fiddle with where on the LP surface you will achieve tangency. The saving grace is that alignment need not be at all exact, because the best you can do is to achieve a single point of tangency on the LP surface. Precise positioning only affects WHERE that single point will be located.
Resistors are ageless, except carbon composition ones (cylindrical in shape and brown in color, bearing circumferential colored rings that denote the value in ohms) which can indeed drift over time and due to temperature. I suppose it would not hurt to check carbon resistors to determine whether the value is within ~10% of the schematic value. If so, I would leave them alone. If not, replace. |
The impedance of any ESL is a complex function of many factors, but basically an ESL can be viewed as a giant capacitor. Thus it will tend to have high impedance at low frequencies, and the impedance will tend to fall off at the very highest audio frequencies. More than one ESL measures 2 ohms impedance or less at 20kHz, for example. However, that same panel may well measure 100 ohms at 20 Hz. The step-up ratio of the audio transformer is also a major factor in impedance; many if not most "modern" ESLs present a relatively low impedance load as a deliberate design choice, to make the speaker more friendly to solid state amplification. Martin-Logan speakers are a particular example of this. The impedance seen by the amplifier will vary inversely as the square of the step up ratio of the audio transformer. So choosing a high-ish step-up ratio will tend to result in low impedance even across the mid-band. Crossover networks also tend to reduce impedance around the crossover point. My point is that your Joule amps can certainly drive any ESL that is built or modified to work well with a tube amp, i.e., any ESL with a decent impedance curve (e.g., >8 ohms) at low and mid-frequencies. There is little electrical energy required at 20kHZ, so a very low impedance at such high frequencies is nothing to worry about. For example, my SL speakers measured impedance at ~500Hz in stock form was about 5 ohms or less, not good for an OTL. When I removed all the crossover parts from my SLs and substituted the treble audio transformer with a full-range audio transformer, the impedance now measures 20-25 ohms at mid-frequencies. Needless to say, my Atma amps are in OTL heaven driving my 845PX speakers. And the improvement in sound afforded by getting rid of the crossover brought tears of joy to my eyes.
Try an original Quad 57 or a KLH9. Those great speakers were made to mate with tube amps from the get-go. You will be amazed. |
