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Balancing Thorens TP25 Tonearm

AngelAT

AngelAT

Well-Known Member
Hello fellow AKs!

Recently I acquired a nice Thorens TD 125 mk2. Restored the electronics, including replacing caps and pots. Relubed the moving parts, etc.

It came with a sagging tonearm weight so I bought a replacement rubber coupling part (iirc from Italy) and replaced it.

IMG_8780.jpeg

But now I cannot balance the tonearm - headshell flies in the sky. To balance it with the weight halfway I need to add about 6 grams. I am using a generic AT3600 cartridge.

IMG_8789.jpeg

Am I missing something or have I messed up?

Any ideas are appreciated!

Thanks in advance!
 
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How much does your counterweight weigh? It may be a heavier counterweight to be used with heavier cartridges. There is a similar looking cw on the bay that weighs 90 grams and being sold as the standard counterweight.
 
Thanks for stepping in @Blue Shadow !

Even though it felt almost impossible, comes out that my counterweight is 115 grams. ‍♂️

I will now try to find a solution- either find a 90 grams one or try to balance by adding weight at the headshell.
 
Nice turntable! I think it deserves a nicer cart than a 3600, a definite "lightweight" in the AT line, both figuratively and literally. Also what is the VTF for your cartridge? You might find that the counterweight works better with a higher compliance stylus with a lower tracking force.
 
AngelAT said:
Hello fellow AKs!

Recently I acquired a nice Thorens TD 125 mk2. Restored the electronics, including replacing caps and pots. Relubed the moving parts, etc.

It came with a sagging tonearm weight so I bought a replacement rubber coupling part (iirc from Italy) and replaced it.

View attachment 3815765

But now I cannot balance the tonearm - headshell flies in the sky. To balance it with the weight halfway I need to add about 6 grams. I am using a generic AT3600 cartridge.

View attachment 3815768

Am I missing something or have I messed up?

Any ideas are appreciated!

Thanks in advance!
Click to expand...

is there an auxiliary weight on the counterweight that can be removed?
 
AngelAT said:
Unfortunately no (or at least I cannot see it). Visually looks exactly like the lighter version.
Click to expand...
can you shave some diameter off the rubber washer so the counter weight can go closer to the tonearm pivot? Or substitute a thinner washer?
 
There might be the possibility of trading this heavier cw for the stock lighter one.

But it might be best to to just step up to a nice heavy cartridge. The manual for the arm should mention the weight range for the tonearm and mention the need for the heavy cw at a certain weight.

Or maybe drill a hole through the cw to remove metal.

The 99 gram weight does show up on eBay and your local audio shop might be able to help, too.
 
Last edited:
AngelAT said:
Hello fellow AKs!

Recently I acquired a nice Thorens TD 125 mk2. Restored the electronics, including replacing caps and pots. Relubed the moving parts, etc.

It came with a sagging tonearm weight so I bought a replacement rubber coupling part (iirc from Italy) and replaced it.

View attachment 3815765

But now I cannot balance the tonearm - headshell flies in the sky. To balance it with the weight halfway I need to add about 6 grams. I am using a generic AT3600 cartridge.

View attachment 3815768

Am I missing something or have I messed up?

Any ideas are appreciated!

Thanks in advance!
Click to expand...
Why does the weight have to be half way? Just balance it. wherever the weight ends up is fine.
 
curtisw99 said:
Why does the weight have to be half way? Just balance it. wherever the weight ends up is fine.
Click to expand...
His weight is too heavy to balance such a lightweight cartridge. This weight is like using a late 70s arm with a permanently mounted aux weight, only needed if the cartridge weighs more that 10-12 grams generally. Even all the way forward the arm is still pointed to the sky.
 
My recommendation would be some blue tack in the head shell to get it balanced, distributed as evenly as possible, while continuing the search for a lighter counterweight. I've done this with a few Ortofon SPU head shells that did not contain the lead weights pre mounted inside. My arm needs 31g total (spec from Ortofon) to balance and so far I've not noticed any problems with this approach.
 
captskippy said:
blue tack in the head shell
Click to expand...
He probably needs a sheet of lead because the at is under 6 grams and the heavy counterweight is probably for a cartridge heavier than 10-12 grams.

The OP info shows him in Switzerland. I expect he can find the right weight in Europe very easily but at a cost, bay examples are a c-note US. He might be able to find someone to trade with.

A 20 centimes coin might be able to make the arm/cartridge useable.
 
Blue Shadow said:
His weight is too heavy to balance such a lightweight cartridge. This weight is like using a late 70s arm with a permanently mounted aux weight, only needed if the cartridge weighs more that 10-12 grams generally. Even all the way forward the arm is still pointed to the sky.
Click to expand...
Something is off. It balanced before the sagging weight was fixed.
 
curtisw99 said:
Something is off. It balanced before the sagging weight was fixed.
Click to expand...
This was not mentioned.

He has the heavier counterweight for this arm at 115 grams, the stock cw is 90 grams. This is how the arm is adjusted to use with heavier cartridges. It does not have an auxiliary weight to use in addition to the regular weight.

He chosen to use a lightweight cartridge, the AT 3600 @ 5.3 grams.

Adding weight to the arm, a lead sheet for the headshell or lead tape, like for racketball rackets along the arm tube would allow balancing and adding proper tracking force.

Having a counterweight made to fit the arm that weighs about 90 grams would also work.
 
Looking at the pics a little more closely, and assuming pic one is before and pic 2 after, it appears that the new rubber sleeve is not allowing the counterweight shaft to slide all the way forward toward the pivot as it contains a collar. I am thinking removal of the counterweight shaft and the rubber sleeve and trimming off most of that collar or cutting it off completely may work (if it can be removed and reused) but an easier solution may be to simply take a measurement of the shaft and old rubber sleeve and go purchase some rubber tubing from HD or Lowes and fit new tubing...and then slide the shaft all the way forward to where the gap between the sleeve and the tube inside gimbal housing is roughly the size of the first pic? Unfortunately I do not know the proper size tubing for this tonearm.
 
captskippy said:
Looking at the pics a little more closely, and assuming pic one is before and pic 2 after, it appears that the new rubber sleeve is not allowing the counterweight shaft to slide all the way forward toward the pivot as it contains a collar. I am thinking removal of the counterweight shaft and the rubber sleeve and trimming off most of that collar or cutting it off completely may work (if it can be removed and reused) but an easier solution may be to simply take a measurement of the shaft and old rubber sleeve and go purchase some rubber tubing from HD or Lowes and fit new tubing...and then slide the shaft all the way forward to where the gap between the sleeve and the tube inside gimbal housing is roughly the size of the first pic? Unfortunately I do not know the proper size tubing for this tonearm.
Click to expand...
This is what I saw as well, the new washer is also twice as thick and pushes the weight rearwards
 
Simple logic says: The counterweight is ment to deal with higher masses or Thorens wouldn't put it on. Increase weight, either by adding something or going with a heavier headshell. Done.
 
borchee said:
Simple logic says: The counterweight is ment to deal with higher masses or Thorens wouldn't put it on. Increase weight, either by adding something or going with a heavier headshell. Done.
Click to expand...
Or as stated get the correct 90 gram counterweight.

We are dealing with a tonearm that uses different mass counterweights for the different weight cartridges and specifically a very lightweight cartridge and the counterweight for the heavier cartridges.

He is in Switzerland, the land of Thorens and readily available parts. Maybe even original parts for this but they are expensive, $100 plus shipping which since it is on the continent it won’t be the $70 I see in the bay listings.

Heck there may even be someone that is making replacement counterweights for this arm at a much reduced price. There is a US seller who offers a replacement weight but the listing says nothing about diameter of the hole to fit an arm or the mass of the weight. A worthless listing without critical information.

Maybe we can get @AngelAT to drop in and discuss the steps forward and hopefully a resolution to the problem.
 
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