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Old 3rd February 2018, 03:28 PM   #1011
gpapag is offline gpapag  Greece
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Turntable speed stabilty
This must be it Scott, as it was the only flexible arm then.
NAD offered the 5120 with two versions of tone arms: either with the flexible wand or with a typical alum tubular wand but kept the fluid damper and suspended mass on both. The arm assembly was plug-able. You could have one arm set for one cartridge.
The tubular arm was identical with the arm of the Lenco L-800.

One day I will get a friend’s 5120 with the flexible arm for some bench tests.

George
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Old 3rd February 2018, 03:51 PM   #1012
gpapag is offline gpapag  Greece
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Some tonearm porn reading enjoyment for the weekend
Tonearm Reviews | Stereophile.com

George
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Old 3rd February 2018, 05:08 PM   #1013
lcsaszar is offline lcsaszar  Hungary
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And some more about "The ugly duckling" from 1984 (sorry it was reviewed in the Hungarian audio magazine, but some online translation service might be able to translate the text to English):

Introducing
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Old 3rd February 2018, 05:43 PM   #1014
gpapag is offline gpapag  Greece
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Thank you Laszlo.
Unfortunatelly the Google translate needs some more work for to produce meaningful results.
Can you please describe only what is under the heading "Méréseinkhez" (measurements) ?

And here is what Audio magazine had to say about this TT (pages 34-40)
http://www.americanradiohistory.com/...io-1984-02.pdf


George
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Old 3rd February 2018, 05:50 PM   #1015
lcsaszar is offline lcsaszar  Hungary
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Well, something like this:

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Old 3rd February 2018, 06:00 PM   #1016
gpapag is offline gpapag  Greece
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Yes, I tried this but what I read is not meaningful enough to understand what the plots describe.

George
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Old 5th February 2018, 07:42 PM   #1017
Hans Polak is offline Hans Polak  Netherlands
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What to think of this image from the Hungarian test, resp. a Panasonic, a Pioneer and the NAD 5120 TT ?
No time scale (55 Hz square wave ?) and no amplitude, but the NAD does seem to be the worst damped of the three, resonating with a seemingly high frequency (1 Khz ?)
A translation could help to better understanding .

Hans
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Old 6th February 2018, 06:56 AM   #1018
lcsaszar is offline lcsaszar  Hungary
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Quick translation:

The measured data of the turntable are nothing special. The speed is accurate, the wow is higher than what today's modern machines produce, but still better than the rather modest factory specs. The noise is average. Interestingly the acoustic feedback curve is not nice either, we expected better from this machine. Not that the unwanted signal is too high, but it occurs in a rather broad band (20-55 Hz), and it even shows up beyond 10 kHz again.
We do not want to comment the frequency plot: we had a Tesla VM2102 pickup in our test sample, and we know that from the NC450 turntable test. The current curves are quite similar to those of the past.
The effect of the damping device can be measured very well. In order to demonstrate it, we gave 5 graphs instead of a single one on fig.12. On the flat arm first we set the damping to Q=2, then we started changing the resonance frequency. We got the upper graph at 7, the lower at 14 Hz. On the top graph hardly any peak — well known from the vast majority of turntables — can be seen. On the bottom curve the system is detuned, the shape of resonance resembles to what we know, apart from the dip at 7.5 Hz. Next we kept the frequency constant (around 9-10 Hz), and varied the damping: first disabled it (upper graph), that set it high (Q=2), resulting more even graph with less resonances. The last graph was taken from the tubular arm (resonance freq = 10 Hz, Q=2). The resonance remained moderate again. As we can see, the DVA system is really effective.


Graph 9 and 10: frequency plot and crosstalk, L and R
Graph 11: Acoustic feedback
Graph 12: left upper: Q=2, f=7Hz, left lower: Q=2, f=14Hz; middle upper: Q=0, f=10Hz, middle lower: Q=2, f=10Hz; right lower: tubular arm Q=2, f=10Hz

Square waves are at 1kHz

My comment is that the flexible flat arm (made of PCB :-)) is not the best idea. I prefer a lightweight but rigid arm.

Last edited by lcsaszar; 6th February 2018 at 07:03 AM. Reason: typos
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Old 6th February 2018, 08:01 AM   #1019
gpapag is offline gpapag  Greece
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Thank you Laszlo

George
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Old 9th February 2018, 03:59 AM   #1020
Hiten is offline Hiten  India
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Thanks Hans for explanation. And others for great links and information.

-x-x-x-

The NAD and Dual tonearms are wonderful. Specially Dual. NAD tonearm Patent link it says on page 9 (?) due to flat strip of tonearm the horizontal yield of resonance is very virtually zero. If vibration/resonance energy can only be transferred how come horizontal resonance/vibration yields to zero ?

How about using Rochelle Salt as damping material ? We can drain the energy by using this material by bulb, resistor or other load.

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