Thorens TD 160: Subchassis damping

[Wes_in_VA]

I've installed cork on the subchassis of my TD 160 per the Chadwick mods. I'm curious how much damping I should get with that? There's much less ringing to the subchassis now, but it's not totally gone.
I'm wondering if I should have used more Permatex to get better adhesion of the cork to the metal all the way around...but I don't relish the thought of having to pull the cork off to redo it!

 

[bob06]

When i did my 160 i put cork on the top and bottom of the sub chassis.

 

[Wes_in_VA]

Yeah, that's what I did, too; I'm just curious how much of a difference I should expect.
For instance, when I damped the top plate with dynamat, it went from ringing substantially to being totally dead. Same thing when I damped the platter of my Technics SL 20.
With the subchassis on this, the cork definitely helped the ringing, but it's still there. I'm wondering if I should have heard more of a difference and that maybe I didn't adhere the cork well enough.

 

[bob06]

Mine made a big difference. I used a clear silicone that i spread a thin layer over the hole thing. Then used a small wooden roller and rolled it on. So maybe you didn't get good adhesion.:scratch2:

 

[marcmorin]

Yeah, that's what I did, too; I'm just curious how much of a difference I should expect.
For instance, when I damped the top plate with dynamat, it went from ringing substantially to being totally dead. Same thing when I damped the platter of my Technics SL 20.
With the subchassis on this, the cork definitely helped the ringing, but it's still there. I'm wondering if I should have heard more of a difference and that maybe I didn't adhere the cork well enough.

Just a silly question on my part, but what makes the subchassis ring during play? Who's in there tapping on the thing? Subchassis noise in the sprungy type I'm most familar with comes from A: motor vibration in the top plate fining its way to the springs via the studs, B: acoustic/mechanical energy finding its way to the springs/ subchassis via the studs. Platter/bearing noise
into the subchassis cannot be damped externally since that noise travels longitudinally through the metal.

 

[Wes_in_VA]

Just a silly question on my part, but what makes the subchassis ring during play? Who's in there tapping on the thing? Subchassis noise in the sprungy type I'm most familar with comes from A: motor vibration in the top plate fining its way to the springs via the studs, B: acoustic/mechanical energy finding its way to the springs/ subchassis via the studs. Platter/bearing noise
into the subchassis cannot be damped externally since that noise travels longitudinally through the metal.

:lmao:
Marc, you mean you don't have turntable trolls like I do????

My feeling after reading about the mods for the TD 160 was "why not" on the subchassis damping. I may just put things back together as is for now so that I don't have to go through the mess of removing this stuff.

 

[bob06]

It may not be needed but does it hirt it. :scratch2: I would think any dampening that would cut down on noise or vibrations would be a good thing.

 

[marcmorin]

It may not be needed but does it hirt it. :scratch2: I would think any dampening that would cut down on noise or vibrations would be a good thing.

I don't disagree, but finding what exactly is making noise and why, then addressing those issues seems the logical path instead of a shotgun approach. Not trying to tell anybody what is best for the Thorens, but in ARs I've gotten in that tons of stuff has been added to address what they thought may have been going on always has to be removed to "cure" the original ills. Most of the time adding material to the subchassis throws the suspension tuning so far off, that any "cure" is far outwieghed by the new "disease"

 

[Divotdog]

I don't disagree, but finding what exactly is making noise and why, then addressing those issues seems the logical path instead of a shotgun approach. Not trying to tell anybody what is best for the Thorens, but in ARs I've gotten in that tons of stuff has been added to address what they thought may have been going on always has to be removed to "cure" the original ills. Most of the time adding material to the subchassis throws the suspension tuning so far off, that any "cure" is far outwieghed by the new "disease"

If you are using cork, there is no significant weight added to the subchassis, considerably less weight than putting a LP on the table, I frankly can’t imagine why you wouldn’t add it. :scratch2:

 

[Ilikevinyl]

I put lightweight adhesive rubber foam on both sides of the subchassis. You can find it at craft stores. It's very lightweight and works great.

 

[marcmorin]

If you are using cork, there is no significant weight added to the subchassis, considerably less weight than putting a LP on the table, I frankly can’t imagine why you wouldn’t add it. :scratch2:

I understand........and really I should have posted the pounds of goop I've had to remove. And the fancy patterns the goop has been made into. :scratch2:

so actually back to the original question.......is this to stop soundwaves from bouncing around inside the plinth and subchassis?

 

[Divotdog]

I understand........and really I should have posted the pounds of goop I've had to remove. And the fancy patterns the goop has been made into. :scratch2:

so actually back to the original question.......is this to stop soundwaves from bouncing around inside the plinth and subchassis?

That would be the primary reason on the TD 160 & 145, unlike the AR and the TD 150 they have a large subchassis that will reflect vibrations all over the inside of the plinth.

 

[Wes_in_VA]

That would be the primary reason on the TD 160 & 145, unlike the AR and the TD 150 they have a large subchassis that will reflect vibrations all over the inside of the plinth.

Okay, so if this is the case, then my issue with the cork that I applied not "deadening" things enough really isn't a problem, since I'm more concerned about reflections? Is my thinking in line with this line of reasoning?

 

[marcmorin]

Okay, so if this is the case, then my issue with the cork that I applied not "deadening" things enough really isn't a problem, since I'm more concerned about reflections? Is my thinking in line with this line of reasoning?

Yeah, because once noise is in the metal all the goop in the world on the outside doesn't stop any sound traveling through the metal. Which is why you didn't have a bottom cover on the XB. That's just a reflecting board.

 

[Pio1980]

Just a silly question on my part, but what makes the subchassis ring during play? Who's in there tapping on the thing? Subchassis noise in the sprungy type I'm most familar with comes from A: motor vibration in the top plate fining its way to the springs via the studs, B: acoustic/mechanical energy finding its way to the springs/ subchassis via the studs. Platter/bearing noise
into the subchassis cannot be damped externally since that noise travels longitudinally through the metal.

As I see it, the arm terminates into the sub-chassis and lacks sufficient damped (dead) mass to suppress the modulation fed into it thru the stylus and it's termination in the cart. Listening to the gimbal thru a stethoscope will show how lively an individual example on a given TT may be and all that goes into the subchassis to excite it.

 

[bob06]

Thorens did it to there TD-160 Super and there TD-147 that I know of. Could be more. So if they did it then it's good enough for me.

 

[Wes_in_VA]

Well, I decided to suck it up and remove the cork I had already applied and redo it with a better layer of Permatex. I'm really having fun with this project, so why not spend a bit more time making it exactly what I want.

 

[bob06]

Right on. :thmbsp: