Thorens bounce

p.robustini

p.robustini

Active Member
Hi guys.
I have a problem when tuning the suspensions of my modded Thorens TD-165.
The mods are a zinc subplatter from a TD-160 (my 165 has a 10 mm shaft) and Linn springs.
The TD-165 has a motor protection rod and the transport locks. Both prevent the subplatter and platter to ride low: either the platter hits the rod, or the subchassis sits on the wooden blocks where the locking screws are inserted.
The original springs had become too weak over time. Two of them were almost completely tightened even with the original resin subplatter. So I bought some new spring sold as Thorens but I found out they were actually Linns.
As expected, the Linn springs are stronger than the Thorens, and they locked the subchassis under the top plate.
Installing the zinc subplatter didn't help much. The subchassis had the tendency to be stuck under the top plate anyway. I added some adhesive tar sheets to the subchassis to make it heavier and I managed to level the it to float in the small space between the protection rod/locking blocks below and the top plate above.
There is a bounce but I'm not convinced it is good: I also have a TD-160 and another 165 in house now; they both lack a protection rod and the transport locks - their bounce is therefore way much freer, ample, and prolonged.
I've considered removing the protection rod but I don't know how much play would I gain from it, since the transport locks would hinder the subchassis to ride much lower anyway.
Is it normal to have a limited bounce amplitude in decks with those protections compared to those who don't have them?
Or am I getting something wrong?
I'd like to obtain the same bounce of the other two decks but it seems not possible with that limited play!
 
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My guess is the higher rate springs are messing things up for you. The post that keeps the motor from bending should not really play into it all that much unless you really push down hard. I actually measured mine once with and without the post in, and it was only about 1/4" of travel difference.
 
Might not be able to get it to the same suspension level. But... if it does bounce freely and doesn't touch you're ok, as long as it doesn't top out or bottom out when the normal amount of vibrations/footfalls/etc occur.
 
The seller told me he contacted the manufacturer of the springs (so apparently they are not even Linn but third party); according to the manufacturer, those springs are made to upgrade Thorens TTs of the 160 series from the sonic point of view, not from the quality of bounce. The higher rigidity of the suspensions would allow for an improved sound and a more stable suspension: in other words, it would sound better just because it is more rigid than the original.
Another point of the manufacturer is that the springs are meant to be used with the bundled grommets (no washers included). But being thicker than the originals, they increase the compression and it is impossible to detach the subchassis from the top plate!
I achieved a fairly good bounce with a TD-160 and a TD-165 with original springs. Although not 15 second bounces, when I tap the spindle during play the stylus doesn't skip; if I tap the 165 with these third party springs with the same amount of force it DOES skip, since it is a more rigid system...
According to the manufacturer, I shouldn't assess the kit from an aesthetic point of view or from an automotive point of view. Up to 40 Thorens users have thanked him for the sonic improvement after having installed his kit...
 
The spring suspension is supposed to isolate LF audio freqs from the TT to avoid LF feedback from the speakers, the spring rate idealized for that. Floor induced sway is another matter that varies, but is typical for most lighter sprung TTs on unstable floors.

Sent from my SM-N900V using Tapatalk
 
gip111 said:
I thought if the springs were longer perhaps get longer screws to keep the tension lower but I'm not sure how those screws are fixed to the top.
Click to expand...

The tension on the spring doesn't change once the mass is suspended. It's the suspended mass that sets the tension, and compression amount from static height. The Linn spring will be 3.2hz resonate frequency when it is mass loaded to a height of 30mm
 
marcmorin said:
The tension on the spring doesn't change once the mass is suspended. It's the suspended mass that sets the tension, and compression amount from static height. The Linn spring will be 3.2hz resonate frequency when it is mass loaded to a height of 30mm
Click to expand...

True but I was responding to the OP about the sub-chassis locking into the top plate and led me to think the springs were longer.

BTW, is there a way to check the proper tension or bounce on a stock TD-145/TD-160?
For the longest time my 145 with the slightest movement, the platter would rub on the rod. A half turn on all three springs took care of that.
 
I'd also like to know a better way than the "watch the bounce" method. I like things that involve measurements and such, not just "it looks right". I would also presume that the springs need to be compressed to the same amount in order for things to work right.
 
All you have to do is buy a record weight to add more mass to get a nice bounce. You'll have to always use the record weight then. I definitely wouldn't use the record weight on the original Thorens TD-160 platter mat, nothing is holding the record up on the record label underneath. You'll definitely dish the record then! A different platter mat you'll have to use then.

https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1280&bih=607&q=turntable+record+weight&oq=turntable+record+weight&gs_l=img.12..0i24.3523.8291.0.10538.23.20.0.0.0.0.608.3234.0j2j5j3j0j1.11.0.ekpsrh...0...1.1.64.img..12.11.3222.7pGwUHwdTLg
 
I've taken the original springs from another TD-165, just to understand if the original ones on my TT really had really weakened.
They appeared to be not able to sustain the added mass of the zinc subplatter.
So I reinstalled the resin subplatter and, guess what?
Same problems!
In order to distance the platter form the protection rod by 2-3 mm I had to compress the closest spring a lot. A few more compression would stuck the subplatter under the top plate.
Just to be clear: while doing all this attempts I'm using an original Thorens belt and the cartridge mounted, the Funk Firm Achromat and an old record on. I also check the distance to the protection stud by reversing the platter...

I tried to measure the gap between the top plate and the sub platter when the latter is resting on the wooden blocks with the transport screws. It appears to be about 2-3 mm! So I have 2-3 mm as vertical clearance to level the subplatter!? Is it normal?

I am considering:

1) removing the transport locks assembly (and maybe the motor spindle protection rod, too)
2) or abandon the idea of installing a TD-160's zinc subplatter in a TD-165 (I will maybe try this on the TD-165 with no locks and rod)
 
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Ilikevinyl said:
All you have to do is buy a record weight to add more mass to get a nice bounce. You'll have to always use the record weight then. I definitely wouldn't use the record weight on the original Thorens TD-160 platter mat, nothing is holding the record up on the record label underneath. You'll definitely dish the record then! A different platter mat you'll have to use then.

https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1280&bih=607&q=turntable+record+weight&oq=turntable+record+weight&gs_l=img.12..0i24.3523.8291.0.10538.23.20.0.0.0.0.608.3234.0j2j5j3j0j1.11.0.ekpsrh...0...1.1.64.img..12.11.3222.7pGwUHwdTLg
Click to expand...

I have a 300 g graphite clamp I stopped using after having bought a Funk Firm Achromat - it didn't improve the sound anymore.
But yes, I noticed a better suspension when I put it back on the modded thorens...
 
gip111 said:
True but I was responding to the OP about the sub-chassis locking into the top plate and led me to think the springs were longer.

BTW, is there a way to check the proper tension or bounce on a stock TD-145/TD-160?
For the longest time my 145 with the slightest movement, the platter would rub on the rod. A half turn on all three springs took care of that.
Click to expand...

I've read that one should turn the springs until the bottom end (the smaller side) of each spiral is directed towards the subchassis' spindle. This way the tonearm base will be centered and the bounce will be vertical.
This did not solve my problems, though... ;-)
 
Adjust the platterheight to about 6mm and you should be in the ball park. Measure this with the mat and a record on the platter. Finetune from there to ensure free floating and enough room for the suspension to work. It isnt much you need, in practical use the platter never bounces like when you tap it. I dont know the springs you have but unless they are so long and stiff they push the subchassis against the top no matter how you set them i think you should be able to set it up. If not, then you could add mass to make it work i suppose.
 
gadget73 said:
I'd also like to know a better way than the "watch the bounce" method. I like things that involve measurements and such, not just "it looks right". I would also presume that the springs need to be compressed to the same amount in order for things to work right.
Click to expand...

Absolutely correct. That's why I set all my suspensions up outside of the table first. I can take measurements,I can add mass as needed where, I can watch jounce, I can find best position of spring to negate "spine". etc.etc.etc.
 
marcmorin said:
Absolutely correct. That's why I set all my suspensions up outside of the table first. I can take measurements,I can add mass as needed where, I can watch jounce, I can find best position of spring to negate "spine". etc.etc.etc.
Click to expand...

Don't you agree that if I did this on this kind of deck I'd risk having the subchassis too low (resting on the transport lock assembly) when I'd put it back in the plinth?

Anyway, I got a fair bounce back by reisntalling original resin subplatter and Thorens springs. Kind of 5 second bounce, constrained in amplitude in those 3 mm clearance that the plith allows. And the springs are rather tightened!
So, is it nonsense to install a zinc subplatter in a TD-165?
 
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