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Old 17th November 2013, 10:01 AM   #1101
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Originally Posted by Brumm View Post
Ok, thanks for the explanation. The big question is if the inertia of the rod (be it glass or whatever) and the bearings on its ends would not be larger than the friction of the bearings against the rod. Otherwise stated: would the arm, moving up and down, be able to turn the rod? It would need bearings with very low resistance I think.
It would be worth to make an experiment, imho. Anyone having a 4-bearing arm up for checking this?

Greetings, Hansrudolf
Some are saying that the vertical armwand motion should be as stationary as posssible !! what seems to be the case with this arm ( Colin's design ) . ( at least to a certain degree ) .

It sounds plausible to me that we donot want the armwand to get launched during a warp .. or even at micro scale movements .

another thing : does a record cutter head remains stationary during the cutting process ??? well... make up your mind if that's the case .

Paul
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Old 17th November 2013, 04:22 PM   #1102
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Paul: Bo's original design with the rolling knife edge bearing was the extreme case of full and easy motion for the arm with respect to riding a warp as it could rock back and forth (note it is not really up and down but back and forth) easily. When Bo changed to the current version where the only play was that of the bearing race performance improved. The fact that if the arm had to drag the carriage up the wall of the glass tube to play a warp is a good thing. The less free motion the arm has in this plane the better. As for playing severely warped records, I have over a period of time come to understand and agree with Bo's position that this is simply a stupid thing to do and that it should not be a concern as far as arm design goes. No matter how well your arm will track a warm you can not and will not ever make it sound good. Buy a flat copy of the record and enjoy the music. Best regards Moray James.
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Last edited by moray james; 17th November 2013 at 04:28 PM.
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Old 17th November 2013, 06:44 PM   #1103
bgruhn is offline bgruhn  United States
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Originally Posted by moray james View Post
Paul: Bo's original design with the rolling knife edge bearing was the extreme case of full and easy motion for the arm with respect to riding a warp as it could rock back and forth (note it is not really up and down but back and forth) easily. When Bo changed to the current version where the only play was that of the bearing race performance improved. The fact that if the arm had to drag the carriage up the wall of the glass tube to play a warp is a good thing. The less free motion the arm has in this plane the better. As for playing severely warped records, I have over a period of time come to understand and agree with Bo's position that this is simply a stupid thing to do and that it should not be a concern as far as arm design goes. No matter how well your arm will track a warm you can not and will not ever make it sound good. Buy a flat copy of the record and enjoy the music. Best regards Moray James.
Hi Moray, Bravo! I second your comments almost in full. It is the up/down/forward/back interpretation that I will forever have problems with. Draw a circle or look at the front wheel on your bike. Draw or imagine a horizontal line extending out from the axle to the circumference of the wheel. Let this represent your tone arm. Put a stylus on the end of it and a warped record under it. Along comes the warp which being an inclined plane drives the stylus to assume the new position in space which is vertically displaced from the previous position, aka "up". Now let the arm wand and stylus tip remain located at the horizontal position. Pick a point on the wheel +90 deg from the previous position. Rotate the wheel the same amount that the warp lifted the arm wand in the first case. Now we observe that the point at the top of the wheel has moved ALMOST purely along a horizontal line, or forward or backward. Contrast that with the almost purely vertical displacement of the point on the horizontal axis.

To be fair in this discussion I recognize that these motions do follow a circular path (arc) and can not be taken as pure horizontal/vertical vs up/down motion. What you call them depends on where you look at the wheel. IMHO the motion of the arm wand at the record level is overwhelmingly UP/DOWN. I have the greatest respect for what Bo has created and subsequently how Colin has advanced Bo's work. Kudos to both. But I think that the forward/back, no up/down was a marketing ploy, perhaps even a red herring.
Respectfully submitted,
BillG
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Old 18th November 2013, 09:08 PM   #1104
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Originally Posted by bgruhn View Post
Hi Moray, Bravo! I second your comments almost in full. It is the up/down/forward/back interpretation that I will forever have problems with. Draw a circle or look at the front wheel on your bike. Draw or imagine a horizontal line extending out from the axle to the circumference of the wheel. Let this represent your tone arm. Put a stylus on the end of it and a warped record under it. Along comes the warp which being an inclined plane drives the stylus to assume the new position in space which is vertically displaced from the previous position, aka "up". Now let the arm wand and stylus tip remain located at the horizontal position. Pick a point on the wheel +90 deg from the previous position. Rotate the wheel the same amount that the warp lifted the arm wand in the first case. Now we observe that the point at the top of the wheel has moved ALMOST purely along a horizontal line, or forward or backward. Contrast that with the almost purely vertical displacement of the point on the horizontal axis.

To be fair in this discussion I recognize that these motions do follow a circular path (arc) and can not be taken as pure horizontal/vertical vs up/down motion. What you call them depends on where you look at the wheel. IMHO the motion of the arm wand at the record level is overwhelmingly UP/DOWN. I have the greatest respect for what Bo has created and subsequently how Colin has advanced Bo's work. Kudos to both. But I think that the forward/back, no up/down was a marketing ploy, perhaps even a red herring.
Respectfully submitted,
BillG
Yep ! I agree with the geometric thingy and it all makes sense and also not that hard to follow when we apply the math . I mentioned up and down motion as that's what the eye can see

I'm more interesting in what people say about the audible effects ... stationary vs smooth and easy vertical motion ??

THX for the inputs guys !

Paul
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Old 21st November 2013, 10:58 AM   #1105
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Bill,


I must say I'm flattered for any sort of reference to any advancement on Bo's work, judging by clearaudios latest offerings it appears it was seminal not to mention not referred to enough, funny enough we share some heritage in my 1/4th swede . For such a technically imperfect medium I think we have a lot to learn yet on playback of this medium. Pivoed arms didn't do it for me, perhaps it was phase anomalies even so slight, but as muh as there are huge gains in a linear arm there are just as huge gains in a well designed riaa stage, I've tried all active, no likes here. Still the most mmusical sounding was and is passive 2122hz filter followed by an active 50hz 500hz zero filter, of course with the debated 50khz time constant included, my ears tell me this is a must regardless of debate .



Colin

Last edited by vynuhl.addict; 21st November 2013 at 11:00 AM.
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Old 24th November 2013, 11:58 AM   #1106
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Hi Colin ,

Perhaps we should not pay too much attention to the technical tonearm subject , just enjoy it and have it tracking our precious record collections !
I fuly agree with you about the sonical superior advantage of the LT vs ordinairy gymbal , although many would like to kill me for saying this

As for the signal amplification / riaa etc. much , much more to discover at
that stage indeed . there's an interesting thing going on on this forum .. the salas jfet simple passive phono amp .

I'm using a jfet stage to boost the mc output level only , all the rest is build
up around vacuum tubes .

Paul
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Old 25th November 2013, 01:53 AM   #1107
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I couldn't have said it better Paul!. Much RIAA work has been done for us, it really ultimately comes down to taste and topology . Since we're.dealing at the micro level every bit counts!.


Colin
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Old 30th November 2013, 09:01 AM   #1108
kffern is offline kffern  Australia
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Default perseverence

Iíve been a bit quite for a while, some of you may have been wondering what I was up to?
DIY linear tonearm

I changed the wire to trans-fiís excellent wire and it still wouldnít track a single turn.
My suspicions were the bearings which I had just washed out. Tried washing them out in my WD40 alternative Ė Inox. Still no joy. Washed out in WD40, spun them slowly in a drill.
3 weeks of stuffing around with changes to the carriage and just a few more grey hair and a sniggering wife. Wasted another $40 on another set of sealed bearings from RS supplies. Went to the same routine of washing and spinning.
I was tempted to give up but that would only upset me even more so I kept going.
Today I decided to increase the spacer between the bearings from 6mm to 8mm (12mm glass tube).
Still no luck. Then went back to the 5mm spacer from when I used a 10mm steel rod.
Hasnít missed a track since then.
I had the Ė Ĺ the diameter in my head from somewhere in the thread.

Just goes to show you canít take anything for granted with this thing. It all depends on your particular carriage, bearings and rod.
Never give up!!
Kffern
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Old 30th November 2013, 01:41 PM   #1109
Pemo is offline Pemo  Mexico
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Quote:
Originally Posted by kffern View Post
Iíve been a bit quite for a while, some of you may have been wondering what I was up to?
DIY linear tonearm

I changed the wire to trans-fiís excellent wire and it still wouldnít track a single turn.
My suspicions were the bearings which I had just washed out. Tried washing them out in my WD40 alternative Ė Inox. Still no joy. Washed out in WD40, spun them slowly in a drill.
3 weeks of stuffing around with changes to the carriage and just a few more grey hair and a sniggering wife. Wasted another $40 on another set of sealed bearings from RS supplies. Went to the same routine of washing and spinning.
I was tempted to give up but that would only upset me even more so I kept going.
Today I decided to increase the spacer between the bearings from 6mm to 8mm (12mm glass tube).
Still no luck. Then went back to the 5mm spacer from when I used a 10mm steel rod.
Hasnít missed a track since then.
I had the Ė Ĺ the diameter in my head from somewhere in the thread.

Just goes to show you canít take anything for granted with this thing. It all depends on your particular carriage, bearings and rod.
Never give up!!
Kffern
Photos please
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Old 1st December 2013, 09:36 PM   #1110
kffern is offline kffern  Australia
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This is an old picture. It's currently disassembled.
I will change the wood dowel to aluminum in a week or so.
It consists of 3x10x4 bearings. using 3mm screws which have a long shank, blank brass standoffs as spacers with a transistor isolating tophat at the end,
3mm plexiglass. Riding on a 12mm glass tube held on a threaded bar with a few o rings and bolts. I will post a picture when finished.
My next attempt will use a Lenco collar with an old japanese arm riser.
Kffern

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