Decoupling a counterweight (CW) creates a spring mass damper. The behavior of a spring mass damper is a peak followed by a reduction in level, there are loads of YouTube videos that will explain this in detail. The issue is the PEAK which will be a mechanical amplifier. This peak WILL be in the audio band amplifying the cartridge output at whatever the peak frequency is. If the CW is rigidly coupled to the stub and the stub is rigid to the arm then the only resonances to deal with are the arm/cart and the primary (including harmonics) bending mode of the arm wand. A good analogy here is a dog with a very heavy weight on its tail as the tail wags the tail will transfer the movement to the dogs body.
To turn LP groove modulation into an electrical signal the cartridge body is the Zero reference and stylus movement with respect to the cart body produces the signal. If the stylus and cartridge body both move the same then there will be NO signal output. So the cartridge body MUST remain absolutely still so the only part moving is the stylus to faithfully reproduce the amplitude portion of the audio signal. If the CW is decoupled it will at some frequency wag the tonearm so the cartridge is nolonger a Zero reference as it's moving, warps and eccentricity will compound this error.
Some low end Rega arms use a plastic CW stub so replacing this stub with a steel one is a good upgrade.
I modified a Technics EPA100, this arm has variable dynamic damping, which is a weight and spring with damping oil inside the CW and a dial on the outside to vary spring pressure. Replacing this with a rigidly attached CW provided significant improvement in performance both measured and audible.
That is typical language of a reviewer, it looks like the legs of the rhino stuck in the mud ......
By the way, the videos on YT are no guarantee, many big name turntables used decoupled counterweights with great results, the MA 707 arm I own is one of them.
Come on.... a heavier platter means more inertia. More inertia is more constant speed and less fluctuations. These 200 gr weights are not designed to strain the platter bearing. The plater bearing is the direct drive motor's shaft itself. I used direct drive turntables since 1982. It was a Dual CS606 wich had terrible feedback and I did not know how to alleviate it. I usually turned the gain from the subwoofer down. Until I discovered these weghts at Amazon. It cut the feedback from the speakers completely. I since have an Audio Technical LP-120. Also direct drive. It replaced the Dual CS606 which was in usage since 1982. No wear or functionality impairment all these years, except feedback for speakers. The weight works fanastically, cuts the vibration and feedback, and stabilizes the platter which is fairly light.
Not to mention that the direct drive Quartz PLL motor, is not impacted by the 200 gr weight. Aftert all it produces pulses that are then transformed into constant rotation of the platter, which is also stabilized by this central weight.
That is a topic that all the reviewers mention, it is also repeated by whoever wrote the review of which I attached the link above. Everyone says: "the problem with the DD is that the motor, being attached to the platter, transmits its vibrations directly to the plinth, and from there to the tonearm. Instead, a rubber strap absorbs all the vibrations of the motor, preventing it from transmit to the structure "
I ask: all the manufacturers of TT DD did not realize that? They are fools ? How many RPM does a belt drive motor turn compared to 33 1/3 or 45 RPM for a DD? What magnitude of vibrations are we talking about when we make this crude comparison? I think it is not supported by scientific data, I always find it very simplistic.
Has anyone had a chance to use the DD Teac TN400 platter here? Magnetic levitation...yes, just like Japanese trains! butoooooo the detractors say that it is not perfect because when it is levitating it can oscillate and rub against the walls of the shaft ..... and the friction of the belt does not rub at two points, the motor pulley and the platter?
Everything is debatable, but I don't like arguments without technical foundations.....the legs of a hippopotamus in the mud....., why not an elephant? , they would be better basses !
Here is information in the last post, I can not directly attach the file in Word
https://www.vintage-radio.net/forum/showthread.php?t=151890
PS:
I had the opportunity to use it with that same SME tonearm, Mc Intosh MA6100 - Altec Lansing Santana - Ortofon MC20 with step-up transformer. I remember how that setup hit me, great !
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Come on?..... what is that supposed to mean?
You've got 12 posts on here and you're telling me about things I am already enlightened about.
And for good reason, me being a now retired after 45 years in the service business professional, and having repaired/restored more equipment than you'd ever get your hands on.
Thousands of customer's turntables included.
As for your mention of what is known as cogging of DD motors, that's a worn out subject.
Besides, you've stated that "more inertia" platters are heavy, yes they are, and a DD motor driving one isn't affected by the tiny cogging anyway.
And answer me this....
My DD linear tracker has no hearable rotational problems, a W/F rating of a mere 0.025% with a lightweight 2.5 pound platter.
So.... it doesn't NEED a heavy platter, OR an added anti-feedback platter weight.
You're new on here, but before you go around spewing "come on now" to others, check their portfolio first.
Think, before you speak.
a50, I succeed in being misunderstood in my first language! - I found something I can do!
M
No matter what language I use, including foul, some people just don't understand me.
That's a picture of a clutch plate, not a brake. And a manual-clutch Lexus is rare.
tremendous braking
In my experience, if I say a 47 ohm resistor is used for something to limit current or balance out a circuit that I know works fine, I get a bunch of arguments and loads of other suggestions against my comment.That's true, but it has a simple explanation for me. There are people who always want to win the game, and in the exchanges of the forums it is quite common. I think it's called ego, but I don't care, since I always have the last word, for example at home. " Yes my love "
I don't understand why it has to be, or get so complicated, or changed.
Too many people nitpick trivial things endlessly.
I agree, criticizing is easy, but supporting a job done with a simple "Like" or "Well done", is seen less and less, these are difficult times, and all the common sense and solidarity of people who used to . For example this, some photos have been seen by 18 people, but not one comment. Of course, others correct me because I confused a brake disc with a clutch disc in a joke... Do you know how many gearboxes I had to go down to change clutches in my young years? In short, one thing is for sure, they are less and less willing to contribute, especially to me. because there are things that take me a long time because I don't speak English, and on top of that some make fun...
https://www.diyaudio.com/community/threads/turntable-cec-repair-antiskating.388961/#post-7088588
https://www.diyaudio.com/community/threads/turntable-cec-repair-antiskating.388961/#post-7088588
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wiseoldtech :
That "I like" would have been better in my link of the repair of the AS of the TT Cec, which shows that you demand from others what you are not willing to do yourself. But you show me your teeth as soon as you can........ I would tell you to go to .... But, I undestand you, that is a typical projection.
You wrote earlier that "I don't understand why ....." oh come on!
That "I like" would have been better in my link of the repair of the AS of the TT Cec, which shows that you demand from others what you are not willing to do yourself. But you show me your teeth as soon as you can........ I would tell you to go to ....
But, I undestand you, that is a typical projection.You wrote earlier that "I don't understand why ....." oh come on!
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PS:
I had the opportunity to use it with that same SME tonearm, Mc Intosh MA6100 - Altec Lansing Santana - Ortofon MC20 with step-up transformer. I remember how that setup hit me, great !
It wasn't the Santana model, it was this one! It occurred to me to google Santana and I said to myself: That 2-way was not what I heard! I hope you can apologize.
https://stereonomono.blogspot.com/2012/04/altec-lansing-model-nineteen.html
PS:
The critics of those years said that it did not reach 30 hz, which may be true, since in the specs it is not mentioned how many Db +/-
A little history about turntables .......
I bet many didn't know (like me) about the plate suspended in mercury, read, read...
http://www.soundfountain.com/beltdrive/belt-drive-turntable.html
I bet many didn't know (like me) about the plate suspended in mercury, read, read...
http://www.soundfountain.com/beltdrive/belt-drive-turntable.html