Arm cable dressing

We use the Tune Method to evaluate performance

Moderator: Staff

Post Reply
Mikeg
Active Member
Active Member
Posts: 76
Joined: 2007-04-09 19:17

Arm cable dressing

Post by Mikeg »

I came across these two pictures on Linn dealers websites showing two different ways to dress an arm cable. Which is the optimum way? does it make any difference as long as the cable to the p-clip is straight and doesn't impede the suspension?

I currently have mine flat into the new p-clip as per "arm cable 2" but exiting as per "arm cable 1"
You do not have the required permissions to view the files attached to this post.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

What happens after the P-clip doesn't really matter. The suspension doesn't see that part of the cable.

On the one hand yes, dressing the cable so that it doesn't kill the movement of the suspension is good but that is relatively easy to do. And you can achieve that but miss the other function of the cable.

The arm cable acts like a panhard rod on a car. It controls lateral movement of the sub-chassis. The belt is trying to rotate the platter, and the sub-chassis, clockwise. The arm cable resists this movement, or at least it should.

If you understand these two things which you are trying to achieve it's actually quite easy. Usually ;0)

I'm about to put a Rega arm on an LP12 and this is the hardest part about it. I've done it before but I'll admit I've never found a method I am truly happy with. It works, but it's not quite right.
User avatar
John
Very active member
Very active member
Posts: 369
Joined: 2012-02-23 13:42
Location: United States

Re: Arm cable dressing

Post by John »

Here’s a bit from a Linn setup manual:

38. Lock Arm Cable
When the cable is dressed such that it touches nothing between P-clip and arm pillar, does not affect the position of the arm board when plugged in, and does not affect the suspension operation, lock the plug in position with the set screw in the arm pillar using the 1.5mm (or 1.3 mm) Allen key.
Do not overtighten the set screw as this will destroy the tonearm cable.


Of course this process will be a challenge with tonearms that lack the 90 degree din plug which can be disconnected while the suspension is being setup.
User avatar
ThomasOK
Very active member
Very active member
Posts: 4358
Joined: 2007-02-02 18:41
Location: United States
Contact:

Re: Arm cable dressing

Post by ThomasOK »

Mikeg wrote: 2021-07-05 09:51 I came across these two pictures on Linn dealers websites showing two different ways to dress an arm cable. Which is the optimum way? does it make any difference as long as the cable to the p-clip is straight and doesn't impede the suspension?

I currently have mine flat into the new p-clip as per "arm cable 2" but exiting as per "arm cable 1"
I do it with the cable flat as in photo 2, but with the p-clip in the position in photo 1. Doing the arm cable as in photo 1 requires that you put a hard 90° twist at the arm plug which I don't think is optimum.
The LP12 Whisperer
Manufacturer, Distributor, Retailer and above all lover of music.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

ThomasOK wrote: 2021-07-08 22:15 Doing the arm cable as in photo 1 requires that you put a hard 90° twist at the arm plug which I don't think is optimum.
I seem to remember that the twist was the standard recommendation for the Ittok cable? I don't see how it would do any harm.
Mikeg
Active Member
Active Member
Posts: 76
Joined: 2007-04-09 19:17

Re: Arm cable dressing

Post by Mikeg »

Thanks Tom Just what I was after. I had originally set it up as per picture 2 with the cable doubled back after the p-clip but found putting the trampolin on after setting up for a perfect bounce sometimes put pressure on the exiting arm cable causing the armboard to move. With picture 1 there was no such problem.

Putting a twist in the cable is counterintuitive to me as, unless preformed, the cable would always be trying to untwist again putting pressure on the armboard/suspension. I know Linn's original instruction was to twist the cable but that was with the origional p-clip and the cable could only run vertically through it. The original cable was much stiffer than the current T-cable and the twist in the cable could be preformed with a hairdryer.

John is spot on. The suspension is setup with the arm cable attached and when it is attached it should have no effect on the suspension.
User avatar
ThomasOK
Very active member
Very active member
Posts: 4358
Joined: 2007-02-02 18:41
Location: United States
Contact:

Re: Arm cable dressing

Post by ThomasOK »

Yes, we did do the twist with the original cables. They had to go through the original P-clip parallel to the back of the plinth so twisting it at the arm plug had it being flat throughout most of its internal length. Seemingly less likely to put any sideways torque on the suspended parts. With the new P-clip you can have the cable parallel to the sub chassis as it passes through it. The original T.Kable (now Akito cable, but which I prefer to the new T.Kable) you are also dealing with a thicker and wider cable. It is more difficult to twist and is likely to put more stress on the internal wiring. With the new P-clip I don't see any need for it and think it might be detrimental. I haven't actually A/B compared it, however. If you like twisting things, have at it.
The LP12 Whisperer
Manufacturer, Distributor, Retailer and above all lover of music.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

ThomasOK wrote: 2021-07-09 16:28 The original T.Kable you are also dealing with a thicker and wider cable.
Do you think a stiffer cable works better than a softer one? The cables on the RB3000 are very soft and I was thinking of cable tying the two cables together.
User avatar
ThomasOK
Very active member
Very active member
Posts: 4358
Joined: 2007-02-02 18:41
Location: United States
Contact:

Re: Arm cable dressing

Post by ThomasOK »

I think overall softer is better. I don'y see any problem cable tying the cables together, or sliding heat shrink over it and shrinking it in a few places. I would just recommend against over-tightening cable ties as there is at least some indication that compressing the cables isn't good musically.
The LP12 Whisperer
Manufacturer, Distributor, Retailer and above all lover of music.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

ThomasOK wrote: 2021-07-09 17:53 I think overall softer is better.
Interesting. So you don't think the arm cable acts as a 'brace' to stop lateral movement of the sub-chassis?
User avatar
ThomasOK
Very active member
Very active member
Posts: 4358
Joined: 2007-02-02 18:41
Location: United States
Contact:

Re: Arm cable dressing

Post by ThomasOK »

Mr Pig wrote: 2021-07-09 19:43
ThomasOK wrote: 2021-07-09 17:53 I think overall softer is better.
Interesting. So you don't think the arm cable acts as a 'brace' to stop lateral movement of the sub-chassis?
I am very doubtful of that idea. I don't know if Linn ever stated it. It certainly isn't part of their Urika phono stages which have very thin and pliable wires going to the phono stage in a loop. I don't buy that the pull of the belt on the platter can cause lateral motions through the lubricated bearing once the platter is up to speed. Certainly it can on startup, which is sometimes quite visible, but once it is up to a steady 33.3/45RPM the belt relaxes as there is minimal work for the motor to do.

I believe the idea is to make sure the arm cable, as much as possible, has no effect on the suspension. It should neither push nor pull it and should make no change in the behavior of the springs (within reasonable limits of suspension travel). It should also be firmly clipped to the chassis (cross brace and plinth) to keep energy from traveling up the cable into the suspended parts of the table.
The LP12 Whisperer
Manufacturer, Distributor, Retailer and above all lover of music.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

Thank you Thomas, This is such useful information. I really appreciate your advice.
User avatar
lejonklou
Administrator
Administrator
Posts: 6524
Joined: 2007-01-30 10:38
Location: Sweden
Contact:

Re: Arm cable dressing

Post by lejonklou »

Sorry but I have to be contrarian here. When I took Linns courses in the LP12 and system installation in the early 90's, I was told that the arm cable orientation prevented rotational movement of the subchassis, exactly as Mr Pig has suggested in this thread. A proper arm dressing should both stop the subchassis from oscillating horizontally and let it move freely along the vertical axis.

That they later ignored this information (or revised their stance) after having released the Urika is something I questioned but never received an answer to.

Regarding the dressing of the cable, I still favour a 90 degree twist and the cable being completely vertical in the P-clip. But with the T-kable I make the twist over a longer piece of cable than on the old black cable, by partly cutting apart the left, right and ground conductors, so that they are free from one another and can be twisted 90 degrees.

Will try to remember to post a picture when I open an LP12 next time.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

lejonklou wrote: 2021-07-09 22:02 That they later ignored this information (or revised their stance) after having released the Urika is something I questioned but never received an answer to.
I think it's possible that the original AC motor puts noise, horizontal oscillation into the suspension., in fact I think it's pretty likely, and a steadying hand is beneficial. And that's what the arm cable can do.

With a better, smoother drive, as you might have on a later deck with a more sophisticated motor system, this might not be necessary. And removing that link between the suspension and ground may be beneficial.

Speculation but Linn couldn't really confirm this as it would mean admitting that the Urika compromised decks with the older motor. Guessing obviously.
Mr Pig
Active Member
Active Member
Posts: 57
Joined: 2020-05-05 21:42

Re: Arm cable dressing

Post by Mr Pig »

Just a little aside.

One of the issues often cited with putting a Rega arm on an LP12 is arm height. With Rega arms not having height adjustment, should they have spacers on the Linn, should they not?

I measured the height of the platter to the brace on my RP10 and it is 24.3mm. The RP10 was Rega's best deck with a unique ceramic platter so it seems reasonable to assume they could make that platter any height they like and also that they'd get it right on their top deck.

So if mounting a Rega arm on a Linn, that is the number I'd go for. I recon there will be a little variation in production but I reckon in that ball park of about 24.5mm is going to be about right. I had a lot of different cartridges on the RP10, both Rega ones and taller carts. I did at one point try it with a shim on a taller cart but it made little difference, and the lid hit the counterweight, so I'd get the arm at that sort of height and not worry about it.
User avatar
John
Very active member
Very active member
Posts: 369
Joined: 2012-02-23 13:42
Location: United States

Re: Arm cable dressing

Post by John »

lejonklou wrote: 2021-07-09 22:02 Sorry but I have to be contrarian here. When I took Linns courses in the LP12 and system installation in the early 90's, I was told that the arm cable orientation prevented rotational movement of the subchassis, exactly as Mr Pig has suggested in this thread. A proper arm dressing should both stop the subchassis from oscillating horizontally and let it move freely along the vertical axis.

That they later ignored this information (or revised their stance) after having released the Urika is something I questioned but never received an answer to.

Regarding the dressing of the cable, I still favour a 90 degree twist and the cable being completely vertical in the P-clip. But with the T-kable I make the twist over a longer piece of cable than on the old black cable, by partly cutting apart the left, right and ground conductors, so that they are free from one another and can be twisted 90 degrees.

Will try to remember to post a picture when I open an LP12 next time.
Would be interested in seeing how your arm cable is dressed. Mine is an Audio Origami arm cable and I find it easy to work with.

Image
User avatar
lejonklou
Administrator
Administrator
Posts: 6524
Joined: 2007-01-30 10:38
Location: Sweden
Contact:

Re: Arm cable dressing

Post by lejonklou »

That looks pretty much the same as how I dress the grey T-kable, John. The twist is in the same region, close to the DIN connector to the arm and far from the P-clip and the plinth exit point. Sorry I haven’t posted any picture of this in over a year since my post that you quoted. I keep forgetting to take a picture when being in the LP12-installation flow of mind.

That U-bend at the exit is probably not optimal, though. It would likely be better if it was a larger radius 90 degree bend. But I guess you need another exit hole then. Compromises!
Post Reply