As lcsaszar mentioned in post #2, the delicate cantilever should not be hindered by any sort of friction.
Particularly horizontal.
A slightly off-center record would make the stylus rock back and forth, stressing the needle and possibly even the sonics.
I personally am against any type of damping, asides from the lowering of the tonearm to the record.
From then on, the arm must be friction-free.
Particularly horizontal.
A slightly off-center record would make the stylus rock back and forth, stressing the needle and possibly even the sonics.
I personally am against any type of damping, asides from the lowering of the tonearm to the record.
From then on, the arm must be friction-free.
It doesn't make sense to say if a uni-pivot arm needs damping, or what grade of damping fluid it needs without considering the construction of a particular uni-pivot arm. Damping can be done by damping fluid, gravity, or other means. Take the Graham arm as an example, its damping fluid is at least 8,000 Cst, but 8,000 Cst is undoubtedly too much for other arms such as the Kuzma 4Point arm. I know 4Point is not a uni-pivot arm. A uni-pivot arm needs damping more than a non-uni-pivot arm. For VPI, its heavy base is a device for damping by using gravity.
Generally speaking, damping is beneficiary for almost all pivot arms including uni-pivot arms. Friction is never a problem. All pivot arms including uni-pivot arms are almost fiction free. While playing an eccentric record, overshoot causes more issues than undershoot. Therefore, damping may be needed.
The question isn't whether or not a uni-pivot arm needs damping. The question is optimal damping.
Generally speaking, damping is beneficiary for almost all pivot arms including uni-pivot arms. Friction is never a problem. All pivot arms including uni-pivot arms are almost fiction free. While playing an eccentric record, overshoot causes more issues than undershoot. Therefore, damping may be needed.
The question isn't whether or not a uni-pivot arm needs damping. The question is optimal damping.
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The average (vintage) Dual turntable tonearms are quoted as having 0.015 grams of horizontal friction... and less than that vertically.
I'd say that is an accomplishment.
Well not necessarily true, yes you can overdamp. On my Temaad arm it advises not to go over 10,000cs. Well I tried it & found on what I call my good but not great pressings, an improvement. On my great pressing it became ''jarring & glary'' 7K & 10K together getting around 850K, and great pressings sounded great again.
But I suppose it very much depends on the arm you use.
Cheers
But I suppose it very much depends on the arm you use.
Cheers
Following this, as I have a Kuzma Stogi S 9" unipivot tonearm with its Kuzma oil. I tend to use a lot less oil in the well compared to standard level.
FWIW Kuzma states from its "quoted" Faq:
"Air Line and 4Point – 5,000 cSt ( centistokes)
Stogi S – 15,000 cSt"
Guess I'll need/want to try a thinner oil..
FWIW Kuzma states from its "quoted" Faq:
"Air Line and 4Point – 5,000 cSt ( centistokes)
Stogi S – 15,000 cSt"
Guess I'll need/want to try a thinner oil..
I am somewhat surprised to see Kuzma uses 5,000 Cst damping fluid for their Airline arm although the paddle on the airline arm is small. In my experience with air-bearing linear arms, I wouldn't use any damping fluid over 1,000 Cst. However, it depends on the construction. Even though, it seems very high to me. Walker Audio the Proscenium Black Diamond VI uses 30 Cst, the same as motor oil if I remember it correctly.
People mostly overdamp, wasting cartridge linear displacement following warps, so yes, there is such a thing as too much damping. You ideally need different damping in different directions. Least for vertical, more for swinging across eccentric records and following varigroove, most for the unwanted rotation suffered by unipivots. I arranged different dampings by having two paddles. I use STP engine oil. Much thinner than silicone fluid. See: https://web.archive.org/web/20110724034020/http://www.clarisonus.com/blog/?p=72
It really is every arm design for itself. The arm designers have no doubt spend a lot of listening time on what is best for their arm. received feedback from reviews & customers. So follow their recommendation.
For DIY arms, this is where the fun starts & depends on whether the arm uses a paddle of not, so all you can do is experiment with different oils, they are not expensive, just takes time.
Cheers
For DIY arms, this is where the fun starts & depends on whether the arm uses a paddle of not, so all you can do is experiment with different oils, they are not expensive, just takes time.
Cheers
The article in the link is a very interesting one. In the article, the author's views are following.
1. A uni-pivot only needs to have its center of gravity fractionally below the pivot point.
I agree. In fact, I think the center of gravity should be precisely on the same level as the pivot. It doesn't hurt if it is slightly lower.
2. The stylus tip is on the centre line of the tube.
For uni-pivot arms, it makes sense. However, since the existence of an offset angle, I am wondering if the tip of a cartridge may be needed to be off the center line a little bit in order to keep the balance.
3. The pivot height ought to be at the same height as the stylus tip.
I believe it as well even for non-uni-pivot. However, for short linear arms, it is not possible to do that physically. this is why I try to push the tip of a cartridge as high as possible for my air-bearing arms.
4. You need least damping for normal up and down motion following warps, a little more to follow record eccentricity (which is slower) and most to damp torsional movement of the arm.
It is probably true for a uni-pivot arm with a regular length such as 9" or 12". For short linear arms, I feel ( I use the word, feel, because I don't have any solid evidence to prove my point ) vertical damping may be more important than lateral damping. Furthermore, I believe that vertical damping may be as important as lateral damping for a regular-length uni-pivot arm, too.
Actually, motor oil is messy and difficult to clean. Both oil and silicone fluid will migrate over time. It is easy to deal with silicone fluid. There are many different grades of silicone fluid ranging from 15, 20, 25, and 30 CST. Motor oil is about 30 Cst.
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And do you think the manufacturing designers did not think about this point?
The tone arm needs to pivot, particularly on warped records.
Just like Wise says above.
And please describe the rest of the equipment in use, I would need very good speakers to make out the damping change from 150 to 100 milligrams...that is about the weight of a small pill, I think.
And a 33% change in tracking weight, which itself will mess up the playback characteristics.
Over damping will cause distortion.
Damping rates are discussed in the Control Engineering subject in Mechanical Engineering, also in Electrical Engineering, the over damping can be compared to a too big capacitor.
Our favored author was Prof. K.Ogata...U of Minnesota.
Just my 2 cents.
The tone arm needs to pivot, particularly on warped records.
Just like Wise says above.
And please describe the rest of the equipment in use, I would need very good speakers to make out the damping change from 150 to 100 milligrams...that is about the weight of a small pill, I think.
And a 33% change in tracking weight, which itself will mess up the playback characteristics.
Over damping will cause distortion.
Damping rates are discussed in the Control Engineering subject in Mechanical Engineering, also in Electrical Engineering, the over damping can be compared to a too big capacitor.
Our favored author was Prof. K.Ogata...U of Minnesota.
Just my 2 cents.
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Hi, That will depend on weather or not the arm design contains a paddle. If it does then the oil viscosity very much comes into play. My Temmad arm does not have a paddle, just a 4mm downward facing hardened steel pivot point. Comparing using engine oil filling the well to 8.5K silicon oil what I use now there was an immediate improvement especially in the soundstage & pin pointing instrument location & base response.
Cheers
Cheers
Paddles. Now that's another thing. Ideally, damping would involve a sheet of zero thickness slicing through the fluid with no sideways disturbance, thus providing damping force proportional to fluid viscosity. But a thin sheet will ring. An aerofoil shape would be better. Worse, traditional unipivots immersed a ring well below the pivot point so that rather than slicing, it moved from side to side and slopped the fluid around. Scarcely ideal.
In my opinion, it is not necessary to have a paddle with zero thickness. I don't think it will produce sideway disturbance at such a low speed. An aerofoil shape may defeat the purpose of a damping paddle. For a uni-pivot arm, there are many ways to design the damping mechanism.
For my air-bearing linear arms, I designed the paddles as it in the image. First, I used plastic. The reason to use plastic is to utilize the highly buoyant force of the plastic. Another consideration behind this design is to treat vertical and lateral damping equally. The shape of the paddle is to utilize lateral force and vertical force as well.