Idler Wheel Turntables |
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回覆 (46): Idler Wheel Turntables
 
This empirical test hardly proves anything as the one with the highest momentum (heavy platter and flywheel) would run longer invariably.  
 
It does not shed light either on the arguments put forth to explain why idler wheelers have the best “rock solid pitch”. Putting the idler wheeler to the same test, I am quite certain it would be the very first to come to a standstill.  
 
Stylus drag is a reality beyond question. What concerns us is whether or not it is strong enough to affect speed stability of good belt drive tables.  
 
limage
10-05-20
19:40:02
回覆 (45): Idler Wheel Turntables
About stylus drag, I think we can do a simple experiment on the subject. The requirement is a non-suspended BD table with a separate motor, or a DD, such as the SP 10, with the brake disabled.  
 
Play a lightly modulated LP, eg with a soft classical passage. For BD, move the motor closer to the plinth quickly and smoothly (ie. just let the belt drop but not disturbing the platter), and record the time requires for the platter to slow down to a stop. For DD with no brake, just turn it off and time it.  
 
Repeat the experiment with a highly modulated passage, such as the cannon shot in the 1812.  
 
Repeat once more with the arm raised, ie the stylus not touching the LP  
 
Then we can have at least a rough idea on the effect of stylus drag.  
 
thekong
10-05-20
17:50:48
回覆 (44): Idler Wheel Turntables
 
If the bearing is frictionless, the needle drag will result in large (theoretically infinite) speed variations  
_________________________________________  
 
Yes, only if you are using early Linn table or the like with tank cartridge ploughing heavily through the grooves.  
 
I would see it rather as a transitional drawback when engineers, so obsessed with rumble reduction at that time, went to extremes by putting in tiny motors with the hope of resolving the noise problem once and for all.  
 
Given today's high torque motors along with efficient flywheel offered by heavy platter assemblies, drag imposed by cartridges tracking at less than 2 grams should never again be an issue.  
 
limage
10-05-20
17:01:22
回覆 (43): Idler Wheel Turntables
Just to really create a natural disaster to all those high end turntables out there, The Modified Lenco is now Arthur Salvatore's Reference after 40 years of vinyl playback  
Of course Michael Fremer would not have a Lenco - "over his dead body" given the open friendship he has with Arthur ^__*  
............................................................................................................................  
 
MAY 2010  
 
NOW ADDED TO CLASS A (UPPER) TURNTABLES  
LENCO L 75 IDLER-DRIVE "REFERENCE" TURNTABLE  
(REBUILT BY JEAN NANTAIS)  
This is the finest turntable I have ever heard. Now I've heard countless turntables in the last 40+ years, in my own system as well as in private homes, showrooms and at audio shows, but none of them can match this turntable in its overall cumulative strengths. While it was inevitable that I would eventually discover a turntable to outperform my personal reference of more than 17 years, the Forsell, what is amazing is that this new reference uses a technology (and actual model!) from more than 4 decades ago. Adding to the mystery is that fact that I had long felt this approach was obsolete (based on my actual experiences of the past, and not just simple "theory").  
 
Accordingly, I now feel I have a considerable amount of "investigating" and "explaining" to do, to both my readers and to myself. My immediate goal is to understand and describe the underlying basis of what I (and others) am hearing. I will then attempt to put all of this into a reality-based perspective that will be both helpful in finding a direction/strategy for future component choice while also providing a rational foundation for that direction and choice. Based on my previous history when experiencing something that was radically different, I feel the best approach is to first take a step back and start from the beginning, with a short review of My Turntable History.  
 
read on with the link !!
http://www.high-endaudio.com/RECENT.html
daiwok
10-05-20
16:07:48
回覆 (42): Idler Wheel Turntables
Well gents, since meeting many friends here on 1PK, I might as well get back to my original thread without polluting others. Needless to say I have poisoned many and I am sure many here know that I am a big fan of idler drivers and building my own plinths and tweaks. So I decided to throw something into the fire just to stoke it up to iceland volcanic level  
 
Here is a posting on Arthur Salvatore's web site  
 
---------------------------------------------------------------------------  
 
Idler-Wheel Turntable Observations  
This interesting letter, from a veteran reader, brings up a number of issues concerning idler-drive turntables (and their competition). I've had only limited experience with my Lenco Idler-drive, but nothing I've heard so far allows me to challenge any of the reader's observations below. However, I must still reserve my own judgment at this time. There's only very minor editing and my bold:  
 
"...Having owned many high-end turntables, I ended up with a Garrard 301 for the past 5 years. It seems crazy that I sold my old TT that was worth almost 10 times the cost of the Garrard, but I never looked back. With my experience with the Garrard (and the EMT 930) in the past 5 years, I have accumulated some insights about turntable designs that are far away from mainstream thinking.  
 
The reason for using a belt drive system is to reduce motor noise without resorting to expensive measures. I am now convinced that belt drive was invented not because idler drive was noisy, but purely as a cost-cutting measure; I have measured my Garrard 301, and the amount of rumble is negligible. I am using a 110dB/W/m sensitive horn system, which is -3dB at 20 Hz, and I do NOT hear any rumble. With a good modern reissue LP, the perceived noise floor is no higher than that of a CD. The idler drives are NOT noisy even with a brute of a Garrard motor, if mounted on a proper plinth. Belt-driven TTs often sound unstable. Piano music is often unlistenable because of pitch instability. I have compared my Garrard with CDs of the same piano recordings, and I cannot detect any pitch instability. Rock solid.  
 
Suspended chassis is a disaster. All the suspended decks I have heard, esp. the lightweight ones such as the Linn, lacks the solid foundation necessary to portray large scale orchestral works. Electronic music and small scale vocal or instrumental music might sound OK, but it cannot deal with any large scale music. The combination of belt drive and suspended chassis is even worse, when you add pitch instability into the mix. The soundstage often collapses when things get a bit more complicated, and the imaging rapidly gets confused. The Garrard imaging is rock solid from the lowest PPP to the loudest FFF.  
 
The notion of a frictionless bearing is totally misguided. Noiseless, yes, but frictionless, no. The problem lies with the variable needle drag when a record is played. Is it easier to control your car speed driving on ice or on a proper road surface? If the bearing is frictionless, the needle drag will result in large (theoretically infinite) speed variations. You then have to rely on the motor (via a stretchable rubber band) to try and correct that speed variation.  
 
The engineers at Garrard understood this all those years ago, and added an eddy current brake to the drive mechanism. The brake imparts a constant drag on the platter for the motor to work against. Any variation in needle drag is tiny in comparison and has no effect on platter rotation speed. This results in rock solid pitch. The only modern TT design I have come across with a similar feature is Tim de Paravicini's magnetic drive design. Indeed, it was Tim who revealed this secret to me when I discussed TT design with him two years ago.  
 
The Garrard has obvious design weaknesses too. The motor is extremely powerful, and the energy needs to be sunk into a massive plinth or one with constrained layer damping. I went the massive route and used a backbreaking slab of marble. The bearing design is also ancient, running the spindle directly on a copper thrust plate. Analogue Tube Audio in Germany markets a ceramic ball bearing with bronze thrust plate replacement, which reduces the bearing noise to a negligible level. This bearing is state of the art and is comparable to any bearing on the best modern decks. The platter is also a bit resonant, but this can be overcome with damping and/or platter mat selection. I use a suede mat from Acoustic Solid, first suggested to me by Jean Hiraga.  
 
Even with escalating price that came with the Garrard craze, this turntable (and the 401) still represents remarkable value and is highly competitive or even superior to what is available today."  
 
daiwok
10-05-20
16:03:41
回覆 (41): Idler Wheel Turntables
 
 
My dear CP,  
 
Sorry I must have sent you the wrong file.  
 
He could not be me because judging from his agility of fingers in the rendition of the art of smoking, the beautiful phrasing, most admirable tempo changes interweaved with immaculate puff of majestic air, he is well approaching the paragon of perfection.  
 
The sheer grandeur of style should take me no less than 10 more years just to imitate !  
 
 
 
limage
09-02-04
19:33:00
回覆 (40): Idler Wheel Turntables
 
 
 
CP, how can you be sure that's a cigarette in young limage's hand?  
__________________________________________________________  
 
Because other than the photo that he showed us, he also sent me this video of his babyhood which he seems to be so proud of. :-)  
 
 
 
http://static.youku.com/v1.0.0002/v/swf/qplayer.swf?VideoIDS=17394250&embedid=-&showAd=0
cpsjj
09-02-04
16:05:41
回覆 (43): Idler Wheel Turntables
The Lenco drive system is really a lot niftier then we think.  
 
The short version of this story is:  
If it won’t start, lower the motor nose a bit.  
If it has an abrupt, loud, jerky start, raise the motor nose a bit.  
The idler arm spring is not the real problem, the motor position is.  
A jerky start can sometimes also be remedied by adjusting the power switch position, such that the motor only starts after the idler wheel makes contact.  
 
For those of us with a mechanical interest, here is the full story:  
Why doesn't my platter turn ? my motor is running fine  
Why does my platter only start on 78 rpm ??  
Why do I hear the motor springs move when I switch on?  
 
The poor idler arm spring is blamed for almost all Lenco idler drive problems.  
Most of the time, putting in a stronger spring solves the problem in the sense that it works after that, but that is not the whole story.  
This little spring is not supposed to provide the force needed to prevent “slippage” between the motor shaft (or the platter) and the idler wheel.  
The motor springs are supposed to provide that force.  
If that statement seems nonsensical, let’s look at how the Lenco design works, it’s quite clever:  
 
 
 
So, how does it work?  
Upon switch-on, the motor starts turning, and the idler arm spring gently pulls the idler wheel into contact with the platter and the motor shaft.  
Now, one of two things will happen, depending on where the motor shaft makes contact with the idler wheel. This "point of engagement" is the key. As you can see from the drawing, The distance between the platter and the motor shaft, as well as the diameter of the idler wheel determine where that point is.  
 
A) The point of engagement is on or above the 45 degree line in the drawing.  
In this case, the idler wheel will turn with the motor, but it will not drive the platter, it will slip there. IT DOESN’T WORK!. Twisted Evil  
 
B) The point of engagement is below the 45 degree line.  
This is the situation in the drawing. Now, magic happens.  
The idler wheel pulls itself tightly in between the platter and the motor shaft, pushing the motor down a bit in the process, and gets a 4 kg plateau up to speed in no time.  
IT WORKS! Dancing  
 
When you think about it, it takes a lot of energy to get that heavy plateau started, and thus we need to have a lot of friction between the idler wheel and the motor/platter. The little idler arm spring is in no way powerful enough to provide enough force to cause that much friction. So this is not how it works.  
The lenco mechanism is a nice example of a “grabbing” or "self-locking" mechanism, much like that employed in those machines that shoot tennis balls at you (or baseballs on this side of the ocean). If the motor was powerful enough, and could move downward far enough, it would actually throw the idler wheel right to the other side of the motor shaft. Shocked  
(Try feeding wood into a table saw the wrong way.... same thing)  
 
Any friction between the motor and the wheel would try to rotate the wheel. Friction between the platter and a wheel which is trying to rotate would try to push the wheel to the left. If the wheel moves to the left a bit, it also pushes the motor down a bit, in against the motor spring. This increases the friction at the motor and at the plateau, which causes more rotation, which causes more force to the left, which…. Well, you get it. Both frictions amplify each other, we have the mechanical equivalent of the famous feedback howl. The wheel will dig itself in, pushing the motor down as far as it needs to in order to maintain contact with both the shaft and the platter. Nifty, isn’t it?  
What is missing in the above scenario if the point of engagement is too high is an UPWARD component to the force on the idler wheel. The wheel is not pushed up against the platter, and that is exactly why it slips there.  
The 45 degree line is magical, because that is where the wheel can start "swinging around" the motor shaft without having to push the motor down first. (there must be better way to explain that, but I can't think of one right now..)  
 
So.. basically, the force to counteract the friction is supplied by the motor springs. They are not there merely to kill vibrations, they are an essential part of the drive system’s friction regulation mechanism. The little idler arm spring is only a catalyst, once the drive has “engaged”, you can take it out completely, the platter will keep on turning.  
The motor position will adjust to the amount of force needed to drive the plateau, is another way of putting it.  
 
Now that we understand how it works, let's look at the motor.  
The first thing to note is that the motor shaft is tapered, which means a different point of engagement at different rpm settings, unless the motor is angled upwards a bit in order to compensate for this. (which it is, or should be). If it will only start on 78 rpm, that’s the difference..  
The only real variable in positioning the motor are the nose springs. Lenco has gone through a few different lengths and strength of these springs. Now that we know the symptoms of an incorrect position, we can experiment to get it right.  
 
Ideally, you want the engagement point to be just below that magical 45 degree line. That will make for a nice, smooth start.  
If the motor hangs too low, there will be too much initial upwards force, which gives an abrupt, jerky start, with a lot of (audible) motor movement.  
If there is a difference in start up behaviour at different speeds, the motor's upward angle is not optimal.  
Of course, if the motor is not running yet when the idler wheel makes contact with it, the start will always be smooth, regardless of the point of engagement.  
On some models, it is possible to adjust the position of the power switch, such that power is only applied to the motor after the idler wheel makes contact.  
 
Why does a stronger idler arm spring help? A stronger spring gives enough starting friction to help get the motor below that magical line, where it should have been already.  
 
And finally, a note for those who swap a 50 hz motor for a 60 hz one:  
Because the diameter of the shafts is different, the point of engagement will shift, and you may have to tinker with the nose springs a bit.  
 
And another thing.... I have seen some Lencos with bent idler arms, perhaps because someone has tried to solve a start up problem. The idler wheel should be plumb vertical, and at a tangent to the platter, much like the cantilever to the record.  
 
 
Text by Sander  
Illustration by Trond
daiwok
09-02-04
01:41:27
回覆 (42): Idler Wheel Turntables
Kris - so Limage is smoking the plant behind the BC1 ? carpet match the speakers its all about the WAF (Wife Approval Factor) :-)
daiwok
09-02-04
01:04:48
回覆 (41): Idler Wheel Turntables
 
Sing,  
 
Yes I have seen the protoytype air bearing and suction turntable from Lin. I guess I better ask him to employ a rim drive :-)  
 
~~~~~~~~~~~~~~~~~~~~  
 
I ask Lin it costs more than USD2000 ~.~  
 
Cheers  
Sing
TaiMonSing
09-02-04
00:58:09
回覆 (40): Idler Wheel Turntables
 
 
 
 
Photo of limage's shoe in 2009
kris
09-02-04
00:48:47
回覆 (39): Idler Wheel Turntables
 
 
 
 
 
 
 
Good evening Gentlemen,  
 
Just retuned from my golf day, shocked by limage's photo of the young James Dean posing next to the BC-1 and obviously, interrupted my sleep. Before I surrender my highest compliment on his taste in fashion (and the color of the rug), CP, how can you be sure that's a cigarette in young limage's hand? And if you look closely at his shoes, this is the scary part, I saw him wearing almost exactly the same style shoes just the other day at jules in 2009!  
kris
09-02-04
00:46:23
回覆 (38): Idler Wheel Turntables
 
 
CP,  
 
The story went something like this: my girlfriend liked the B & O speakers because of the cute speaker stands. She paid half the cost. I got the Spendors, she got her stands. Fair deal, wasn't it?  
 
 
 
 
 
 
 
limage
09-02-04
00:39:36
回覆 (37): Idler Wheel Turntables
1973 was the year I left Hong Kong and ended up in UK
daiwok
09-02-04
00:28:38
回覆 (36): Idler Wheel Turntables
Driving a pair of Spendor BC-1 in the year 1973  
-----------------------------------------------------------------------------  
 
 
 1月4日 - 加拿大蒙特利尔博物馆被盗。  
  1月8日 - 谢赫·穆吉布·拉赫曼就任孟加拉国首任总统。  
  2月13日 - 新华社报道,1972年是解放以来中国电力发电站装机最多的一年。  
  3月7日 - 新华社报道,中国发展组合机床取得显著成就。  
  4月10日 - 中国决定建设邯邢钢铁、煤炭基地。  
  4月15日 - 中国春季广交会开幕,与中国发展贸易的国家和地区达140多个。  
  5月4日 - 中国日本共同投资施工建设中日海底电缆。  
  5月17日 - 美参议院专门小组开始水门事件听证会。  
  5月14日 - 美国宇航局 (NASA)在肯尼迪宇航中心用土星5号运载火箭发射了“天空实验室”  
  6月28日 - 中国成功进行了一次氢弹试验。  
  7月16日 - 中国成立计划生育领导小组。  
  7月20日 - 澳大利亚的悉尼歌剧院落成,同日李小龙逝世。  
  8月5日 - 中国全国环保会议召开,制定《关于保护和改善环境的若干规定》。  
  8月8日 - 金大中遭绑架事件。  
  8月22日 -基辛格出任国务卿。  
  8月27日 - 中国第一台百万次集成电路电子计算机研制成功。  
  9月3日 - 中国第一台天文测时、测纬光电等高仪研制成功。  
  11月8日 - 西藏军区在海拔3800米高寒地区大规模种植冬小麦丰收。这是西藏历史上农业发展的重要变革。  
  11月12日 - 蒋经国首先提出十大建设中之前九大建设。  
[编辑本段]出生  
  2月21日——曾宝仪,台湾主持人、歌手。  
  3月13日——黄金宝,香港自行车选手。  
  4月6日——宫泽里惠,日本演员,歌手。  
  4月10日——罗伯特·卡洛斯,巴西足球选手。  
  4月29日——杨牧青,著名书画家、文化学者。  
  7月4日——神威乐斗(Gackt),日本歌手。  
  8月19日——马高·马特拉斯,意大利足球球星。  
  9月11日—— 苏有朋,台湾著名演员,歌手。  
  9月13日——陈慧琳,香港著名歌手,演员。  
  9月18日——马克·舍特尔沃斯,南非企业家。  
  10月11日——金城武,演员。  
  10月13日——松岛菜菜子,日本演员。  
  10月22日——铃木一朗,日本旅美棒球选手。  
  10月22日——曾子墨,凤凰卫视主持。  
  11月17日——董卿,中国中央电视台主持。  
  11月21日——金玉婷,中国女演员。  
  12月19日——反町隆史,日本演员。  
[编辑本段]逝世  
  1月22日——林登·约翰逊,美国总统 (1908年8月27日生)  
  7月20日——李小龙,演员兼武术家 (1940年11月27日生)  
  9月11日——艾德华·伊凡普理查,英国人类学家  
  9月23日——聂鲁达,智利诗人,1971年诺贝尔文学奖得主 (1904年生)  
    
[编辑本段]诺贝尔奖  
  物理:江崎玲於奈、贾埃弗  
  化学:厄恩斯特·奥托·费歇尔、杰弗里·威尔金森  
  生理和医学:卡尔·冯·弗里奇、康拉德·洛伦兹、尼古拉斯·廷伯格、Tinbergen  
  文学:派屈克·怀特  
  和平:亨利·基辛格(Henry A. Kissinger)、黎德寿  
  经济:华西里·列昂惕夫  
    
[编辑本段]奥斯卡金像奖  
  (第46届,1974年颁发)  
  奥斯卡最佳影片奖——《骗》(The Sting)  
  奥斯卡最佳导演奖——乔治·罗伊·希尔(George Roy Hill) 《骗》  
  奥斯卡最佳男主角奖——杰克·莱蒙(Jack Lemmon) 《救虎记》  
  奥斯卡最佳女主角奖——格伦达·杰克逊(Glenda Jackson) 《接触社会》  
  奥斯卡最佳男配角奖——约翰·豪斯曼(John Houseman) 《追逐游戏》  
  奥斯卡最佳女配角奖——塔特姆·奥尼尔(Tatum O'Neal) 《纸月亮》  
  詹姆士布朗特(James blunt)---1973  
  Simona  
  希姆娜  
  You're getting older  
  青春不再眷顾你  
  Your journey's been  
  Etched on your skin  
  往昔印刻在你的容颜  
  Simona  
  希姆娜  
  Wish I had known that  
  我真希望我能明白  
  We seemed so strong  
  曾经存在于我们之间的默契  
  We've been there and gone  
  我们匆匆而来,又转身离去......  
  I will call you up everyday Saturday night  
  我会在每周六约你  
  And we both stayed out 'til the morning light  
  心手相连,直到天明  
  And we sang, "Here we go again"  
  我们一起吟唱着:“Here we go again”  
  And though time goes by  
  纵使青春不再  
  I will always be  
  In a club with you  
  我也会一直在那个酒吧陪着你  
  In 1973  
  在那个令人难忘的1973  
  Singing "Here we go again"  
  吟唱着:“Here we go again”  
  Simona  
  希姆娜  
  Wish I was sober  
  我希望我能保持清醒  
  So I could see clearly now  
  才能看清现实的一切  
  The rain has gone  
  暴风雨已经过去  
  Simona  
  希姆娜  
  I guess it's over  
  是否一切已经结束了  
  My memory plays our tune  
  The same old song  
  那首老歌还一直在我记忆中萦绕  
  I will call you up everyday Saturday night  
  我会在每周六约你  
  And we both stayed out 'til the morning light  
  心手相连,直到天明  
  And we sang, "Here we go again"  
  我们一起吟唱着:“Here we go again”  
  And though time goes by  
  纵使青春不再  
  I will always be  
  In a club with you  
  我也会一直在那个酒吧陪着你  
  In 1973  
  在那个令人难忘的1973  
  Singing "Here we go again"  
  吟唱着:“Here we go again”  
  I will call you up everyday Saturday night  
  我会在每周六约你  
  And we both stayed out 'til the morning light  
  心手相连,直到天明  
  And we sang, "Here we go again"  
  我们一起吟唱着:“Here we go again”a  
  And though time goes by  
  纵使青春不再  
  I will always be  
  In a club with you  
  我也会一直在那个酒吧陪着你  
  In 1973  
  在那个令人难忘的1973  
  Singing "Here we go again"  
  吟唱着:“Here we go again”  
  I will call you up everyday Saturday night  
  我会在每周六约你  
  And we both stayed out 'til the morning light  
  心手相连,直到天明  
  And we sang, "Here we go again"  
  我们一起吟唱着:“Here we go again”  
  And though time goes by  
  纵使青春不再  
  I will always be  
  In a club with you  
  我也会一直在那个酒吧陪着你  
  In 1973  
  在那个令人难忘的1973  
  Singing "Here we go again"  
  吟唱着:“Here we go again”  
  And though time goes by  
  纵使青春不再  
  I will always be  
  In a club with you  
  我也会一直在那个酒吧陪着你  
  In 1973  
  在那个令人难忘的1973......  
 
----------------------------------------------------------------------------------------  
 
Gingers
09-02-04
00:27:07
回覆 (35): Idler Wheel Turntables
 
 
 
My first generation LP12, still in use. There was no repalcement for the failed red light switch and I have to replace with a green light from Apliu Street.  
 
 
cpsjj
09-02-03
23:47:30
回覆 (34): Idler Wheel Turntables
Limage that is some fashion statement ! bewarn that young audiophiles will follow suite ! yes armed with with cigs and a LENCO and you will be a high hand in Hi Fi ;-)  
 
It is so bizzare what after all those years we seem to go back to the same routes ? I guess your visit was a shocking visit to see the LENCO again.  
 
The BC1 are splendid speakers- BTW CP, I have the original Spendor stands if you want to try.
daiwok
09-02-03
23:46:58
回覆 (34): Idler Wheel Turntables
 
 
 
Even a stand like this has bad result.  
 
 
 
cpsjj
09-02-03
23:41:53
回覆 (33): Idler Wheel Turntables
 
 
 
 
This is how the BC1 should be placed, or on any open frame, not too rigid stand.  
 
 
 
cpsjj
09-02-03
23:39:10
回覆 (32): Idler Wheel Turntables
 
 
 
I like the look with the cigarette though. :-)  
 
 
 
cpsjj
09-02-03
23:36:36
回覆 (31): Idler Wheel Turntables
 
 
 
limage,  
 
You put the BC1 on the wrong stand. No doubt you are not keeping it and wasted this excellent speaker.  
 
 
 
cpsjj
09-02-03
23:26:57
回覆 (30): Idler Wheel Turntables
 
 
Driving a pair of Spendor BC-1 in the year 1973  
 
 
limage
09-02-03
23:19:34
回覆 (29): Idler Wheel Turntables
 
 
The first turntable I ever owned was in fact a Lenco, whose model I cannot recall now. It came with an integrated arm, a piece of artifact yet having a pretentious anti-skating device resembling that of the world renowned SME.  
 
The second table I bought was the entrance level hifi grade EMT 150 bare table, where I had the SME 3009 finally installed.  
 
The third attempt, a reference calibre Sony table paired with a very fine Stax tonearm, itself a beauty to behold. The amp was a Luxman integrated unit, chosen because of its highly acclaimed OCL output at 0.05 % THD, a time when spec meant everything.  
 
 
limage
09-02-03
23:18:13
回覆 (28): Idler Wheel Turntables
For those interested in reading the Thread on the LENCO its here  
 
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1157059532&openflup&923&4&&st0  
 
bewarn - you need a few months to absorb all this, after a while it seems to be self glorification from the original poster.
daiwok
09-02-03
22:47:08
回覆 (27): Idler Wheel Turntables
Sing,  
 
Yes I have seen the protoytype air bearing and suction turntable from Lin. I guess I better ask him to employ a rim drive :-)
daiwok
09-02-03
22:23:02
回覆 (26): Idler Wheel Turntables
Frankly despite I'm impressed with the Lenco, I'm still puzzled by why it sounds nice  
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CP "sounds nice" is what it is all about. This is exactly how I felt when I first go the LENCO up and running, I was stunned, then asked why ?? all these years of belt drive - yet older technology sounds better ? my first turntable about 20 years ago was the LP12 Vahalla and since then I have had Michell ORBE, a few Alphason Sonatas, VOYD THE VOYD, and have heard countless turntables, matched with countless arms and carts. The LENCO motor is very simple, very smooth and as I read spins like 1800 rpm - I cannot qunatify this, the idler wheel is very light and has constant contact. The platter is actually even heavier than the Garrard platters ! The turntable rubber mat is heavy and is used to damp out the ringing and does a fine job. The original bearing is not as big as the Garrard, but still nicely precision made by the Swiss. Unlike the Garrard it has a ball bearing at the bottom of the main bearing. I sense the motor is not as powerful as the Garrard, which may cause less rumble, certainly smaller and vibrates much less. Both have sprung suspension to compensate such motor vibration. The springs on the Lenco are much bigger and stiffer than the Garrard springs. Does the motor contact wheel sound better ? I have not heard the VPI with and without the rim drive, may be someone here can share ? the Teres are obviously promoting their rim drive and take note that the Maxon motors they employed previously for their belt drives were also very serious motors.  
 
You even start looking at the question, no suspension is better ? All my previous turntables were suspension turntables, may be with the right plinth no suspension is necessary ? I mean spring suspension done wrong can provide micro oscillation - right ?
daiwok
09-02-03
21:36:29
回覆 (25): Idler Wheel Turntables
 
 
I am never good at memorizing figures, be it start time or 36-24-36. CP, the inquisitive, is right at last. It should be 0.25 second.  
 
Here is the specification sheet that should end this debate to return room to the idler wheels!  
 
 
limage
09-02-03
19:47:36
回覆 (24): Idler Wheel Turntables
Then "the platter to come to speed at 1/10th of a second" must be wrong.  
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what do i know? cp. you tell me. if the platter weighs 2.9 kg, the moment of inertia seems about right making the platter about 32cm diameter. the angular acceleration seems pretty small given the starting torque is only 6kg/cm-2.
drwkng
09-02-03
18:01:12
回覆 (23): Idler Wheel Turntables
 
 
these two statements can't be true at the same time. can it?  
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Then "the platter to come to speed at 1/10th of a second" must be wrong. Perhaps limage is not aware that it's the clutch working.  
 
 
 
cpsjj
09-02-03
17:53:53
回覆 (23): Idler Wheel Turntables
 
 
In 1970 National Panasonic (Technics) had introduced the SP10 direct drive turntable. It was a single unit with no separate power supply. Its speed was regulated by reading the minute fluctuations of the platter with a tachometer and so fluctuations in the turning of the motor could be corrected.  
 
In 1975 the SP-10 mk2 (together with its Power Supply SH-10E) was introduced. It was a great step forward if compared to the technique of the Mk1 and other DD-turntables. The functioning of the Mk2 was quite different, the motor was turning at a given speed which was steered by a set frequency which was generated by a quartz crystal. Hence the turntable's performance is not affected by any altering in the frequency of the mains nor any voltage fluctuation. A fluctuation in speed is instantly corrected by the motor itself without the use of a tachometer or a playback head which reads the magnetic imprints on the inside of the platter (a method Denon used in their DD turntables). This meant a mere perfect performance as far as speed accuracy, wow and flutter are concerned. In order to avoid fluctuations from temperature and those caused by mechanical parts no speed adjustment facility (variable pitch) was incorporated. This was a drawback for people with perfect pitch and for those music lovers who wanted to play a variety of old shellac records which are not always cut at 78 RPM.  
 
A new and unique feature of the SP 10 MkII was the incorporation of a mechanical and electronic brake not encountered on other DD turntables, not even the SP10MKI. It reminded of the direct start of the EMT turntables and the clutch of the Thorens TD-124 and it made the SP-10 Mk2 a true Studio Turntable. Manu radio stations installed the Mk2 for playing 33.33 and 45 rpm discs for the broadcast of music programs.  
 
By increasing the capabilities of the motor and designing refined and complex electronics to regulate the motor's rotation (for smoothing out the shocks when moving from one pole to the next) the SP10mk2 attained its practically incomparable specifications. Instead of the soft mat which was used on the earliest SP10 (SL1000) and SP110 (SL1100) now a hard mat adorned the heavy platter. The hardness is not without significance for the sound performance which is an essential feature of the SP10Mk2.  
 
The platter of the SP-10 mkii weighs 2.9 kg / 6.4 lb. To prevent a turntable platter from sounding like a bell, the inside has to be covered with a sound absorbing material. This can be a layer of a resin like substance as with the early Melco turntables or - as in the case of the Technics SP 10 mkii - with a relatively thick bithumous sheet.  
 
 
 
 
 
cpsjj
09-02-03
17:48:47
回覆 (22): Idler Wheel Turntables
he SP-10 Mk Two has been known for its smashing torque that allows the platter to come to speed at 1/10th of a second  
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The turntable has a starting torque of 6kg/cm-2 (5.2 lbs.inch-2). The moment of inertia is 380 kg/cm-2 (130 lbs.inch-2).  
 
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these two statements can't be true at the same time. can it?
drwkng
09-02-03
17:48:31
回覆 (22): Idler Wheel Turntables
 
 
 
FIRST DIRECT DRIVE PATENT  
 
Thorens developed a direct drive motor way back in the 1920's. Thorens applied for a patent for this direct drive turntable motor, tourne disque in French. On the document is written: "TD à commande directe". It was issued by the "Bureau fédéral de la propriété intellectuelle" (Federal Office of Intellectual Ownership) in Switzerland, on June 21, 1929 and was described in the "Exposé d'Invention". Thorens however refused to use a direct drive motor in the music lover's turntables. At the time the technique was probably too expensive to make it work to perfection. Thorens applied the direct drive technique in the 1970's in their studio turntable. And so did EMT. It was their answer to the success of the Technics direct drive turntables, especially the SP-10 mk2 turntable.  
 
 
 
 
cpsjj
09-02-03
17:39:04
回覆 (21): Idler Wheel Turntables
 
 
 
The SP-10 Mk Two has been known for its smashing torque that allows the platter to come to speed at 1/10th of a second  
___________________________________________________________________________________  
 
The turntable has a starting torque of 6kg/cm-2 (5.2 lbs.inch-2). The moment of inertia is 380 kg/cm-2 (130 lbs.inch-2).  
 
 
cpsjj
09-02-03
17:34:09
回覆 (23): Idler Wheel Turntables
 
 
daiwok,  
 
It's great to see you show up here and started the discussion on turntable construction. There must be many more interesting postings to come up.  
 
Frankly despite I'm impressed with the Lenco, I'm still puzzled by why it sounds nice. As said, every drive will have its own virtues and vices and it all depends on the implementation to enhance the virtues and assuage the vices. However, without knowing the basic reasons why it sounds good, we will be blind to ameliorate the device further. I'll be looking forward to the comparison of friction drive, belt drive and direct drive and hopefully that will shed some light on the basic attribute of different drive mechanisms that affects their sonic characters.  
 
 
 
cpsjj
09-02-03
16:43:43
回覆 (23): Idler Wheel Turntables
Yes Limage has kindly offered me to come to his Den !! I have to wait until I return from my biz trip which will be like end of Feb
daiwok
09-02-03
16:42:45
回覆 (22): Idler Wheel Turntables
Hi limage,  
 
I really envy you; your SP10 II is in impeccable condition. The one I have is also a MK II, but the condition (as least the appearance) is not even close :-(  
 
 
thekong
09-02-03
16:00:36
回覆 (21): Idler Wheel Turntables
 
 
The only table left with me now.........  
 
 
limage
09-02-03
15:45:02
回覆 (20): Idler Wheel Turntables
 
 
Kong,  
 
Yours may be the Mark One, which I also owned at the beginning of time, along with the earliest Linn LP12, EMT 150, Thorens 125 and a most exquisite model from Sony too.  
 
The SP-10 Mk Two has been known for its smashing torque that allows the platter to come to speed at 1/10th of a second, a feature much craved by disk jockeys of yester-years. That does not imply, however, that the Mk 2 is necessarily sounding any better than is the Mk One.  
 
Believe it or not, I find all models, excepting the EMT 150 which is hardly in the same league, sounding very much the same provided sufficient care has been exercised down to every minute detail of setting up. There are 101 ways to get to Rome.  
 
 
limage
09-02-03
15:42:53
回覆 (19): Idler Wheel Turntables
>thekong your a big guy picking on someone of smaller size than you :-) <  
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David,  
 
I would not dare to pick on our Honorary Chairman :-)  
 
The truth is I have learned much, especially speaker placement, from limage. Have you visited limage’s audio den yet? If not, that is something you shouldn’t miss. :-)  
 
 
thekong
09-02-03
15:25:34
回覆 (18): Idler Wheel Turntables
thekong your a big guy picking on someone of smaller size than you :-)  
 
Limage - yes your right, but from experiments overseas from a close friend on the belt drive does not have the same effect as the rim drive both sitting on the same plinth, same platter and same bearing etc. That said, you could argue that his belt drive motor is not on par with the rim drive - the argument can go on and on. I think if we take stock TT's idler and stock DD and just compare with same material plinth for now, then it would be fair to say this particular model "sounds" better than that particular model.
daiwok
09-02-03
15:15:30