Success: Technics SL1200MKII Tonearm Rewire and Damping

[cat's squirrel]

I did a little experiment a few years ago to answer this question.

I added a plasticine-type material to a 100mm square of acrylic. The plasticine had a damping factor of >0.6. I added the material in increments of the same mass as the piece of acrylic, and measured the damping factor of the acrylic + plasticine after each increment added. Then I plotted a graph. I found that I needed at least 8 times the mass of the acrylic equivalent in plasticine to approach the damping factor of the damping compound.

This suggests that if one wants to increase the damping of a structure, to approach the damping factor required needs a lot of damping material. That amount is not practicable in most cases. The case where it is, is when the structure to be damped is ringing, and here, a very small amount of damping, applied in exactly the right position, can reduce the ringing considerably. This won't work if the structure is not ringing, I mean like a bell, like a metal platter.

So, I suppose the answer is, a lot of damping material is going to help, but to be really effective, expect to add a lot!

HTH

 

[musiklava79]

I did a little experiment a few years ago to answer this question.

I added a plasticine-type material to a 100mm square of acrylic. The plasticine had a damping factor of >0.6. I added the material in increments of the same mass as the piece of acrylic, and measured the damping factor of the acrylic + plasticine after each increment added. Then I plotted a graph. I found that I needed at least 8 times the mass of the acrylic equivalent in plasticine to approach the damping factor of the damping compound.

This suggests that if one wants to increase the damping of a structure, to approach the damping factor required needs a lot of damping material. That amount is not practicable in most cases. The case where it is, is when the structure to be damped is ringing, and here, a very small amount of damping, applied in exactly the right position, can reduce the ringing considerably. This won't work if the structure is not ringing, I mean like a bell, like a metal platter.

So, I suppose the answer is, a lot of damping material is going to help, but to be really effective, expect to add a lot!

HTH

You have not replied to my question - I had asked about damping of the tonearm and the wand using different materials, not about using boards. I think we are digressing from the point here. While you argue for the case of using thinner and harder (stiffer) materials, this line of thinking defeats your own purpose. Here you are saying that that resonance (the ringing) is desirable. Then you might as well have an all metal turntable!!! Of course, to my limited knowledge, the universal school of thought is to eliminate this very ringing!

I have read your article posted in another website about this observation using two graphs as statistics. But it will be real helpful if you will explain how you came about your findings. In any scientific paper, the kind of tests conducted, the method, the instruments used to arrive at the findings are at least given. You haven't. You say that a damping factor of .4 is desirable but rarely attainable because of the subtances/materials used. Here you have arrived at a damping factor that is >.6. How did you achieve that?



I'm sorry but I'm finding it hard to be convinced. You are only making a case for these hardwoods and some materials that will mostly not be used by most DIY builders. I had asked about tonearms. Can you imagine using plasticine and acrylic as materials for constructing a tonearm?

You have not taken into account a lot a other factors like the resonance frequencies of the TT motor, the motor and spindle bearings, the different metals used therein. Whether the motor shaft and the platter have been dynamically and statically balanced. Only longitudinal waves have been factored in. What about lateral waves, if any?

Will appreciateto hear your response.

 

[cat's squirrel]

You have not replied to my question - I had asked about damping of the tonearm and the wand using different materials, not about using boards. I think we are digressing from the point here. While you argue for the case of using thinner and harder (stiffer) materials, this line of thinking defeats your own purpose. Here you are saying that that resonance (the ringing) is desirable. Then you might as well have an all metal turntable!!! Of course, to my limited knowledge, the universal school of thought is to eliminate this very ringing!

I am sorry, musiklava, you are making some of this up. I have answered your questions. My point is that it is smarter to make structures of materials that have sufficient intrinsic damping than to use materials with poor damping, and trying to damp the structure with adding a material with more damping. For example, it is better to make a wand from carbon fibre with some damping than to use a metal with virtually none, and add some damping to it. I have never advocated ringing is a good thing in anything audio, but I have experimented with ringing structures, and find a little damping goes a long way.

I have read your article posted in another website about this observation using two graphs as statistics. But it will be real helpful if you will explain how you came about your findings. In any scientific paper, the kind of tests conducted, the method, the instruments used to arrive at the findings are at least given. You haven't. You say that a damping factor of .4 is desirable but rarely attainable because of the substances/materials used. Here you have arrived at a damping factor that is >.6. How did you achieve that?

I am not writing a scientific paper, nor would it help most people. I have outlined my method of determining damping factors of materials, here:
damping factor values : damping factor values

I'm sorry but I'm finding it hard to be convinced. You are only making a case for these hardwoods and some materials that will mostly not be used by most DIY builders. I had asked about tonearms. Can you imagine using plasticine and acrylic as materials for constructing a tonearm?

plasticine, no, acrylic yes! but it would not be my first choice, or my second.

if I am guilty of anything, it is making a case for clever thinking in making a suitable choice of suitable materials. It transpires that from the measurements I have made over many years, that suitable materials are not easy to source or manufacture, or are too expensive. Not my fault. If suitable materials were available to all, were cheap and easily worked, then I'm sure manufacturers of audio equipment would be using them!!

You have not taken into account a lot a other factors like the resonance frequencies of the TT motor, the motor and spindle bearings, the different metals used therein. Whether the motor shaft and the platter have been dynamically and statically balanced. Only longitudinal waves have been factored in. What about lateral waves, if any?

Will appreciate your response.

with regard to 'other factors'. It does not matter. Vibrations are vibrations, and are to be reduced if a non-coloured audio system is to be built. Longitudinal waves are not considered, as, for a plinth built using the above principles, lateral wavers are not a problem until the frequencies are above 1kHz in most cases for normal-sized plinths. The software I have developed calculates the transition frequency where lateral waves become important.


On a personal note, you come over as a little aggressive, I am only trying to answer your questions, whether you want to believe the answers or not is entirely your prerogative.

 

[musiklava79]

I am sorry, musiklava, you are making some of this up. I have answered your questions. My point is that it is smarter to make structures of materials that have sufficient intrinsic damping than to use materials with poor damping, and trying to damp the structure with adding a material with more damping. For example, it is better to make a wand from carbon fibre with some damping than to use a metal with virtually none, and add some damping to it. I have never advocated ringing is a good thing in anything audio, but I have experimented with ringing structures, and find a little damping goes a long way.

Where have I made up anything here? Please read my question in this thread and your reply. I've based my response on your very reply to my question. My intial question was about the use of materials like wood, bamboo and carbon fibre in the first place, to which your reply did not seem to have addressed.

I am not writing a scientific paper, nor would it help most people. I have outlined my method of determining damping factors of materials, here:
damping factor values : damping factor values

I'm referring to your article in damping factor - Audio qualia

plasticine, no, acrylic yes! but it would not be my first choice, or my second.

if I am guilty of anything, it is making a case for clever thinking in making a suitable choice of suitable materials. It transpires that from the measurements I have made over many years, that suitable materials are not easy to source or manufacture, or are too expensive. Not my fault. If suitable materials were available to all, were cheap and easily worked, then I'm sure manufacturers of audio equipment would be using them!!

The normal method for DIY'ers is to use cheap and practical articles of everyday use before resorting to other materials. While you are making a case for hardwood which is expensive in India, if they are available at all, I had suggested some replacements which can be acquired locally at reasonable prices. Please read my earlier post. I've have long experience is the use of timber. We use timber and bamboo almost all the time, hence my suggestion. There are competent Institutions in the area where I live to conduct the test for damping factor and resonance and I have already begun making contact with them. I also took up your kind offer but there seems to have been no reciprocal response from your end, hence the cynicism.

with regard to 'other factors'. It does not matter. Vibrations are vibrations, and are to be reduced if a non-coloured audio system is to be built. Longitudinal waves are not considered, as, for a plinth built using the above principles, lateral wavers are not a problem until the frequencies are above 1kHz in most cases for normal-sized plinths. The software I have developed calculates the transition frequency where lateral waves become important.

I don't know, but I think both of us require a crash course in resonance and vibrations, may be!

On a personal note, you come over as a little aggressive, I am only trying to answer your questions, whether you want to believe the answers or not is entirely your prerogative.

Perhaps those are your personal feelings, not mine. I only requested you to give me a logical answer to my doubts and somehow that seems to be found wanting!

 

[Hari Iyer]

I had a similar tonearm wire overhaul on my Thorens TD145 mk2 - not because i wanted to replace the wire, because the left channel had stopped playing music. I traced it to a badly dis-integrated tonearm wire. The table was vintage more than 45 years old. I unfortunately cannot rip open the tone arm like the OP but only could lay the tonearm wire from outside. Initially tried with the 24awg silver platted copper wire. This sounded awesome but did mask some of the mid bass and lower mids. Also this wire had some skating force having impact on the arm movement. Then i salvage from a usb charger cable which had very thin 32awg tin platted copper wire. Used it for 4 days and it never could breakin properly. They had a huge loss of bandwidth in the midrange and was sounding only lows and highs.

Later i salvaged a 30 year old telephone patch cord lying in my loft which had the exact wire that i was looking for. It was vintage wire with only 4 strands of maybe 48awg copper and each strand was twisted with a layer of cotton string on them. The 4 wires were twisted and had a PE dielectricy. This was bare copper wire and with just 4 strands of super thin wire. Suprisingly even after 30 years the copper had not oxidized. After wiring them from outside it sounded quite harsh but was flat in bandwidth throughout not over or underemphasising any frequency. it was harsh for the entire bandwidth. but i believed in this wire and continued playing my records for two days and afterward the harshness began to diminish and they sounded very smooth and open. I am happy that i went this route and now firmly believe that tonearm wire is as important as a cartridge or a stylus. This wire definetly sounds quite better than the original Thorens tonearm wire. The noise level is zero and there is zero rumble/ feedback even at full volume. I am not sure the cotton in each strand helps to absorb micro vibrations and reducing noise levels.


Thanks for looking.