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Old 11th October 2013, 07:51 AM   #21
volken is offline volken  Netherlands
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Default Testrecord rumble TD124.2

Rumble with a special testrecord from Germany DIN 45544 ! LAB 030 .
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Old 11th October 2013, 06:28 PM   #22
oshifis is offline oshifis  Hungary
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You don't have to use unmodulated groove or blank surface for rumble measurement. I would measure by normal playing conditions (using 330 Hz or 1 kHz test tone groove for amplitude reference).
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Old 12th October 2013, 09:25 PM   #23
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Indeed,

At very least modulated groove provides reference level for signal.

Combined with discless measurement, some manner of groove rumble level may be determined for disc.

Analysis of signal on computer provides much easier interpretation of tracking behavior.
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Old 13th October 2013, 01:53 PM   #24
volken is offline volken  Netherlands
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The drivetrain from the TD124 is rather complex to get a better insight I made a measurement with the messkoppler on the mainbearing without platter.
The max. frequence is 100 Hz and the vibration frequenties are clearly visible .
The next challenge is to link these different frequensies !
Step further is to make the measurement with a accellerometer to ,,bypass,, the tonearm.

The measurement with the rumble test record is limited because you get the interaction with the tonearm , cartridge etc.

Volken
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File Type: jpg IMG_7781.jpg (476.0 KB, 127 views)
File Type: bmp Rumble TD124.2 Messkoppler Motor and steppulley Schopper belt.bmp (104.1 KB, 145 views)
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Old 13th October 2013, 03:15 PM   #25
kevinkr is offline kevinkr  United States
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Volken, interesting motor suspension set up. Can you tell us more?
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Old 13th October 2013, 05:38 PM   #26
volken is offline volken  Netherlands
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Quote:
Originally Posted by kevinkr View Post
Volken, interesting motor suspension set up. Can you tell us more?
Yes these are a own development seems that Thorens used them in the early days here you can see the measurements
Hanze Hifi - TD124
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Old 13th October 2013, 05:52 PM   #27
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Quote:
The drivetrain from the TD124 is rather complex to get a better insight I made a measurement with the messkoppler on the mainbearing without platter.
The max. frequence is 100 Hz and the vibration frequenties are clearly visible .
The next challenge is to link these different frequensies !
Step further is to make the measurement with a accellerometer to ,,bypass,, the tonearm.

The measurement with the rumble test record is limited because you get the interaction with the tonearm , cartridge etc.

Volken
Click the image to open in full size.
Quote:
Originally Posted by kevinkr View Post
Volken, interesting motor suspension set up. Can you tell us more?
Click the image to open in full size.

In the "Restoring and Improving A Thorens TD-124 MKII" thread I found a couple more rumble plots from Volken. One plot of the TD124 with motor spring isolation (like in the photo), the other with rubber grommet isolation (factory method).
There probably wasn't enough discussion on this "mod" and the measurements from it. And now that I am searching for that particular post with the two plots, I can't seem to locate it. (need more coffee)

But as I recall looking at the two plots it appeared that the "spring plot" was a bit quieter than the grommet plot. Although then it might be appropriate to question if there aren't other areas of performance that might be affected by such a mod.

But this does beg comparison to the Garrard 301/401 motor isolation method which also uses springs to isolate. but that method employs springs in all the degrees of freedom that the motor has. for instance it uses springs at an angle to counteract torque force in addition to the pull of gravity. (vertical)

You know, on that TD124 thread of yours, it might be useful to organize each post made by volken. It seems that in every case he produces a measurement document to explain every question that arose in the thread. So a summary of those posts could become an important part of any method of restoration for the beast. At least I'm taking these to heart.

-Steve

Last edited by user510; 13th October 2013 at 05:58 PM.
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Old 14th October 2013, 10:14 PM   #28
AVWERK is offline AVWERK  United States
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Thanx for showing some real measurements that gives us a handle on different methods of reducing vibration.
Looking at the way the springs are touching a hard spacer, it seems practical to decouple even more by using the gel pads in some way to support the springs on both ends.
Might give some damping to the spring and should reduce higher frequency contributions.

Regards
David
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Old 14th October 2013, 11:07 PM   #29
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by volken View Post
Yes these are a own development seems that Thorens used them in the early days here you can see the measurements
Hanze Hifi - TD124
Hanze does not seem to offer these, I'd be extremely interested.. Any suggestions?
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Old 29th October 2013, 02:47 PM   #30
volken is offline volken  Netherlands
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Quote:
Originally Posted by kevinkr View Post
Hanze does not seem to offer these, I'd be extremely interested.. Any suggestions?
Hanze Hifi has the springs in the webshop see Thorens Motor decoupling springs

They ship to the USA too !!

Volken
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