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Minty TD145 only bounces for 1 second

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Minty TD145 only bounces for 1 second

Postby doctor fuse » 04 Jul 2018 20:34

I have just received a minty TD145 that performs perfectly - except I cannot get the suspension to bounce for more than 1 second (let alone 15).

I have adjusted the springs by tightening and loosening the nuts. No difference, at least for duration of bounce.

Nothing is touching (wires, and I have put the platter locking metal piece facing downwards instead of upwards, etc).

Any advice appreciated.

EDIT/UPDATE: I've got it bouncing for around 7-8" seconds now. Can't get it more than that, no matter how much I fiddle.
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Re: Minty TD145 only bounces for 1 second

Postby Japi Roelofs » 04 Jul 2018 21:34

Perhaps stating the obvious, but do you have the tonearm 'loose', so not locked in the armrest?

FWIW I never could get a 15 second bounce on any of the Thorens models I worked on, a couple of seconds seems good enough to me.
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Re: Minty TD145 only bounces for 1 second

Postby doctor fuse » 04 Jul 2018 21:54

I tried both ways; arm loose and in the rest.

I am satisfied with 7-8". What I seemed to understand, was that the spring closer to the arm is tighter, and the other two are looser.
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Re: Minty TD145 only bounces for 1 second

Postby Alec124c41 » 05 Jul 2018 01:01

If there is damping material in the springs, that will cut the bounce time.
I have experimented with using a pinch of fiber, which can be easily adjusted, in a turntable that bounced too much when the arm lowered. It does affect the sound.

Cheers,
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Re: Minty TD145 only bounces for 1 second

Postby tlscapital » 06 Jul 2018 23:17

A little bounce is also all I get and all I need. That since I added mass on both the platter now chromed with 4 layers mats lasagna dampening and convert my tonearm into a heavy-heavy effective mass tonearm.

More important is the horizontality of it all and the 4 to 6 mil. gap between the platter and top plate. A little bounce will still decouple the platter and tonearm from the chassis and plinth. That is what is at stake there.
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Re: Minty TD145 only bounces for 1 second

Postby JDJX » 07 Jul 2018 00:31

What am I missing here?'

The springs are there simply to Help isolate the platter and tone arm from external vibrations from the motor and plinth.

Bouncing of the sprung, floating assembly is the last thing that you would want when playing an LP for obvious reasons.
So, why would anyone want to bounce for 15 times?
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Re: Minty TD145 only bounces for 1 second

Postby user510 » 07 Jul 2018 01:01

doctor fuse wrote:I have just received a minty TD145 that performs perfectly - except I cannot get the suspension to bounce for more than 1 second (let alone 15).

I have adjusted the springs by tightening and loosening the nuts. No difference, at least for duration of bounce.

Nothing is touching (wires, and I have put the platter locking metal piece facing downwards instead of upwards, etc).

Any advice appreciated.

EDIT/UPDATE: I've got it bouncing for around 7-8" seconds now. Can't get it more than that, no matter how much I fiddle.


Am I missing something here? Since when are we worried about how long the suspension bounces? Where is this bit of advise that suggested a 15 second bounce time. If there is one I suspect it is erroneous.

If, with the tonearm free of the parking clip, you get an even vertical bounce with less than slight sideways jiggle, that should be the target goal. Forget about how long the springs oscillate.

-Steve
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Re: Minty TD145 only bounces for 1 second

Postby doctor fuse » 07 Jul 2018 01:03

I have read postings where people swear that the sound gets unreal once the 15 second bounce is achieved. Can't recall where I saw it, but it seems many people were talking about it.

I just wanted to see if I could achieve it, so I could hear for myself.
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Re: Minty TD145 only bounces for 1 second

Postby user510 » 07 Jul 2018 01:17

I should think that the least amount of bounce is preferred. What we want is a stable (unchanging) distance from motor pulley to the platter. This will maintain a truer sense of time (more stable platter speed). Always of concern.

That said, the springs do isolate the subchassis from the motor board and this is essential to the design.

Btw, did the 7-8 second bounce sound any different?

-Steve
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Re: Minty TD145 only bounces for 1 second

Postby doctor fuse » 07 Jul 2018 01:49

FWIW, I couldn't hear any difference between different bounce times.
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Re: Minty TD145 only bounces for 1 second

Postby doctor fuse » 07 Jul 2018 01:51

Also, I am surprised that this TD145 handles footfall and vibrations as well as it does. My TD160 was so sensitive to these things, until I modded it with dollar store plasticine and a birch base.
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Re: Minty TD145 only bounces for 1 second

Postby Spinner45 » 07 Jul 2018 02:30

doctor fuse wrote:I have read postings where people swear that the sound gets unreal once the 15 second bounce is achieved. Can't recall where I saw it, but it seems many people were talking about it.

I just wanted to see if I could achieve it, so I could hear for myself.


Do yourself a favor....
Don't listen to everything spewed online, a lot of it is nonsense.
I agree with the others - too much bounce is a bad thing.
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Re: Minty TD145 only bounces for 1 second

Postby user510 » 07 Jul 2018 02:40

doctor fuse wrote:Also, I am surprised that this TD145 handles footfall and vibrations as well as it does. My TD160 was so sensitive to these things, until I modded it with dollar store plasticine and a birch base.


Often times, when you've got a bouncy floor, and then when footfall is involved, people overlook the one -other- thing that can be the biggest contributor to footfall issues on suspended subchassis turntables; Arm/cartridge compliance match-ups.

If you have a TT with an arm obviously too heavy for the cartridge suspension, like a high compliance cartridge matched to a high effective mass tonearm, it's footfall city...sometimes even when the turntable is not a suspended design. Same TT with a proper arm/cartridge matchup really doesn't have so many footfall issues. And this is on a bouncy floor.

Otherwise, even with a solid flooring, an arm/cartridge system with a resonance happening below the 8 - 12 hz happy range, there can be other problems with playback that take away from the optimal, like poor performance over warps and sensitivity to acoustic borne energies that would otherwise not be noticed. Woofer pumping can happen when the above match-up issues are present.

-Steve
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Re: Minty TD145 only bounces for 1 second

Postby doctor fuse » 07 Jul 2018 02:42

Spinner45 wrote:
doctor fuse wrote:I have read postings where people swear that the sound gets unreal once the 15 second bounce is achieved. Can't recall where I saw it, but it seems many people were talking about it.

I just wanted to see if I could achieve it, so I could hear for myself.


Do yourself a favor....
Don't listen to everything spewed online, a lot of it is nonsense.
I agree with the others - too much bounce is a bad thing.


But if it is on the internet, it must be true - right? :D :^o [-X =D>
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Re: Minty TD145 only bounces for 1 second

Postby vitw1844 » 08 Jul 2018 18:39

Greetings all on this post.

Here was where I first learned about the 15 second "bounce" or swing time needed for my TD150:

viewtopic.php?p=94615

I will repost the points here mentioned:

1) Please be shure to use a belt of correct length (min. 255 mm)
2) for the following steps you must have the belt mounted.
3) In order to get the correct adjustment, please mount the platter and
put the original plattermat and of course a vinyl disc on it.
4) Dismount the three springs
5) Dismantel the springs from the foam material cases
6) Afterwards remount the three springs and have a look for the correct
mounting position. The lower end of the springs must point to the platter
bearing.
7) Only for the older Thorens there is the need to mount an additional
swash plate between chassis and each spring.
Now screw everything together and adjust the three springs. Afterwards
the platter should float for about 6 mm in height parallel to the upper
edge of the chassis/ motorplate.
9) In case the platte is to high, please start the readjustment with the
spring on the motorside first.
10) In case you have the swash plates mounted it is possible to center
the spring by turning the swash plate.
11) Any time you correct the fitting or the preloading of the springs or by
turning the swash plates you have to readjust the height of the platter.
12) By pushing the platter on the spindle the platter must swing freely
and for about 15 seconds


I then posted the original thread almost 8 years ago about my findings on the 15 second "bounce" or oscillation time to aim for with certain Thorens suspended sub-chassis turntables:

viewtopic.php?f=17&t=33519

Note what Joel stated on this thread:

"The exact justage is a garantie for an efficient mechanical filter and to get the Chassis resonance lower as possible."

For the TD320, for example, he gave this explanation as to the reason why exact suspension tuning is important (which I have Google translated from German):

"How important is the dimensioning of the resonance frequency (4.6 Hz) of the mechanical filter. This filter has a slope of 12 dB / octave."

"One octave higher, at 10 Hz +/- 3 Hz, you set the depth resonance of the tonearm.
A well working mechanical filter allows the tonearm to work "undisturbed" at its most critical point! Another octave higher, at 20 Hz, begins about the linear transmission range of the useful signal."

And so this was not hearsay or nonsense, it is true.

From what I understood about his explanation I then posted this:

"Hello Joel, thank you for your expert explanation. Thus now it is all very clear to me. Correct suspension tuning allows the suspension system to act as an effective mechanical filter. The suspension is designed to Help mechanically filter any resonances that may try to find their way to the stylus down to inaudible levels, i.e. well below 20 Hz, so that they do not interfere with the audible frequency range.

This will also explain why the bass frequencies in particular clear up with proper tuning, the stereo image widens, and extra space is heard around the instruments when the suspension is properly tuned. There will be less vibration coming up through the platter to hinder stylus to groove adhesion.

And so it is all about learning the laws of transformation of energy, and, when having a knowledge of these principles, knowing how to apply them through mechanical engineering."

Turntable design is all about understanding about the laws of transformation of energy, and how to damp unwanted ones, as many far more learned contributors on this forum constantly state in their posts.

All the best,

vitw1844
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