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Fun with vinyl measurements

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Balle Clorin

Balle Clorin

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@pma I use SpectraPlus as well. I used the logging function to capture time vs frequency and then took the data and made a linear plot. I've seen polar plots from other users for W&F, but I think I like the linear plot better. This was for 33 1/3 speed. And the sample rate was 48Khz.
View attachment 236018




Here is what my cheap Music Hall MMF 2.1 with AC sync'd motor and belt drive looks like under the same test parameters

View attachment 236020
Your sampling interval seem too long for the plot, looks likevyou are getting aliasing /beating on the mmf. I get a similar beat pattern with WFGUI plots
 

stereoplay

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Recently I got another turntable from Mitsubishi, the Linear Tracker LT-20. It is a more sophisticated motor and motor driver with PLL as the ITT HIFI 8013 (built by Mitsubishi around 1980).

Wow&Flutter:

Screenshot 2022-10-10 15.39.19.png
 
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Balle Clorin

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OK trying to test turntable isolation effects.
Method: Bouncing a ball next to the turntable, trying different set ups, mat on latter, rubber under feet etc, It is not easy to get exact identical ball bounce , even if I marked the spot to drop the ball and use a "guide" for the same elevation'

1667727017793.png


First result, hardly any difference with stylus on a stationary record. left Ball on TT support, middle ball bounced on floow, right, clapping hands next to arm/cartridge
1667729043009.png


With a running 3150Hz test track, with and without mat on platter
1667729199021.png


Can clearly see intermodulation effects form the ball bouncing vibrations below
1667729358613.png



In the recoring I can hear the "knock knock" from the bouncing ball when recording on a stationary record, but using simple earplugs from PC I cannot hear the bounce besides the 3150 tone with platter spinning ,A low pass filter at 1000hz look like this, NOTE. dot sure the differences are real or just a bounce to bounce variation
1667730449771.png


1667731495184.png




Conclusion, variations between bounces ar if the sama order as difference with and without mat, no really significant change, and I cannot relay her any difference either.
SRM rubber mat used witg Gyro clamp used with and without mat
 

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dlaloum

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OK trying to test turntable isolation effects.
Method: Bouncing a ball ned to the turntable, trying different ste ups, mat on latter, tubber under feedt etc, It is not east to get axcate identical ball baunce , even in I marked the spot to trop the mal and use a "guide" for the same elevation'

View attachment 241573
Depending on the construction of your home, bouncing or jumping on the floor near the TT can also be worthwhile - remove the belt from the TT, and gently rest the needle on the platter/record - then record and analyse the output - those needles are incredibly sensitive measurement instruments!
 
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Balle Clorin

Balle Clorin

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1667732337314.png


1667732369933.png



1667733787488.png



1667734108460.png



2mm mousemat rubber runder feed DOES soften/dampen impact of floor vibration from ball bounce form 80cm height



Mousemat rubber under both motor and feet is now best after some optimisation
1667738894449.png



1667748941920.png
 

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Thomas_A

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Not sure what you want to achieve. Impact-isolation (for dance-friendly floor), or acoustic sound-wave isolation?
 
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Balle Clorin

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I do not dance...trying to minimimize structural transmitted vibrations. Nothing I can do with airborne acoustic feedback, besides playing without turntable lid.
I have a theory that spikes are bad for vibration isolation, my TT has spiked feet ( and with spring suspended cassis- at mimimum suspesion during test and normally as that gives minumum w&F), so I tested with rubber and coin under spike.
but rubber under feet increased W&F, I suspect I need to readjust leveling and motor alignment with the use of rubber under feet. Leveling and belt aligment has a large effect on W&F on a Gyro
 
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Thomas_A

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I do not dance...trying to minimimize structural transmitted vibrations. Nothing I can do with airborne acoustic feedback, besides playing without turntable lid.
I have a theory that spikes are bad for vibration isolation, my TT has spiked feet, so I tested with rubber and coin under spike
Ok,

spikes couple so whatever they couple to needs to be inert and damped. A constrained layer board under the TT/spiked feet, and isolation pads under the board should do it.

(And you know, a lid can actually reduce the acoustic impact on the record surface. I measured this many years ago.)
 

dlaloum

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What I ended up with after many similar tests... in a solid brick house with suspended wooden floors (old style solid hardwood).

My Rack is made using several Ikea Lack side tables standing one on top of the other - the internal structure of these side tables, is hexagons of corrugated cardboard, it is very light weight, but is very efficient at damping/absorbing high frequencies - but does nothing at low frequencies. (the space between the lack table legs is precisely rack / component width)

At Floor level I have a large concrete paver, purchased from a garden store (I sealed it with wood oil, to ensure no concrete dust...)
Under the concrete paver, I have 5 of the largest size sorbothane pucks I could find
So heavy mass sitting on springs - very low resonant frequency - high absorbance of low frequency vibrations
An Ikea Lack Table top is then on top of the Paver, with a complete Lack Table on top of it - within this level I have a Power conditioner (glorified integrated power switch, but with some ability to absorb power spikes, and an insurance policy :) ) as well as my HTPC, and Power amp
Then I have another Ikea Lack Table, standing on some quite firm Sorbothane pucks - in this level I have the AVR, and the Phono Preamp.
On top of this Lack table I have the Turntable - the original feet have been removed and small firm silicone rubber ISO feet (5 of them) sit under the TT (the bottom board has a tendency to resonate - so the 5th foot in the middle made a substantial difference!
I also filled the TT plinth, and all available spaces that weren't needed for mechanicals or cooling, with plasticine... (oil modelling clay) - it is an excellent damper/absorber

I have a box hanging around with a wide range of different size silicone and sorbothane pucks and domes, also some magnetic ISO feet, spikes, vibrapods - I experimented with a lot of options - measuring them just as you are... (also did some walking and stomping around the room...)

Keep in mind that there are heaps of variables - and changing a component (eg: changing the Amp or AVR in the stack) would change the sprung mass of the entire rack - this in turn would change the rack's resonant frequency, which could bring it into a problem zone (or not).
A change such as this, could potentially require revisiting the various pucks and changing their springing constants (how firm/soft they are) for optimal results.... this is NOT a one size fits all situation - it is specific to YOUR equipment, YOUR cabinet, and YOUR floor/room.

But YES - remarkable results are achievable - and relatively economical turntables (new or vintage) can provide results that will shame many very very expensive TT's - simply through the benefits of isolation - a well set up isolated TT will always outperform a poorly isolated competitor, even if that competitor is much more expensive!!!

Of course, some such competitors, are expensive due to the extensive isolation and damping built into them... - but this sort of measurement can achieve equivalent results, at far more economical prices.... and it is an interesting and educational process... very rewarding too, when you hear the results!
 

JP

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(And you know, a lid can actually reduce the acoustic impact on the record surface. I measured this many years ago.)

Or just shift it.
 
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Balle Clorin

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..

(And you know, a lid can actually reduce the acoustic impact on the record surface. I measured this many years ago.)


I measured with a lid too, with opposite findings,much worse feedback and more microphony... on a Thorens TD125mkII
 

Thomas_A

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Thomas_A

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I measured with a lid too, with opposite findings,much worse feedback and more microphony... on a Thorens TD125mkII
Have you measured with your current setup (if there is a lid around)?
 

RayKay

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I use this for angles. Spec for AT-OC9ML/II is 23 degrees I have 21 here maybe rise the arm 8mm or so to get 23? The arm will be far from level with the platter then..... Kind of impossible to see SRA with all that glue
https://www.ginifab.com/feeds/angle_measurement/

Are you sure it's 21 degrees?

Shouldn't it be this:

ASR VTA.png


The VTA should be defined by the axis line between the stylus tip and the suspension/pivot point of the cantilever. It is the motion of the stylus tip deflecting this axis line that determines the electrical output of the cartridge. The suspension/pivot point is not visible in the photo so there is margin of error either way, blue or red, but the way I've drawn it more accurately pegs the VTA as 24 degrees, which is closer to AT's spec of 23. If you reposition the origin of the protractor onto the stylus point then the measurement will become apparent.

An example that clearly demonstrates the point is a Shure M44-7 which has a bow shape cantilever. The entire cantilever is curved, but the axis line between the stylus tip and the suspension/pivot point positively defines the VTA.

Shure M44-7 Cantilever.jpg


Ray
 
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Balle Clorin

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Have you measured with your current setup (if there is a lid around)?
Not on my current set up. The custom made lid and support I have now is loose and lid lifted away when playing, I can play with also but a bit cumbersome to lifte it off/on for every record. I may test and record with /without one day. My TD125mkII had a hinged lid that picked up the vibrations and transmitted it to the chassis. My present lid has no contract with the turntable and is probably better, but will transmit vibrations to the common support

1667925130252.png




Found and old feedback recording om my TD125MkII with lid UP and lid DOWN, first verse Deep Purple Highway Star played from CD. SME 3009 II Improved, and a Shure N75 I think
1667927858664.png
 
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Thomas_A

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Not on my current set up. The custom made lid and support I have now is loose and lid lifted away when playing, I can play with also but a bit cumbersome to lifte it off/on for every record. I may test and record with /without one day. My TD125mkII had a hinged lid that picked up the vibrations and transmitted it to the chassis. My present lid has no contract with the turntable and is probably better, but will transmit vibrations to the common support

View attachment 242010



Found and old feedback recording om my TD125MkII with lid UP and lid DOWN, first verse Deep Purple Highway Star played from CD. SME 3009 II Improved, and a Shure N75 I think
View attachment 242015
With a sweep playing from another source and playing a silent groove on the record player you can see the effect on acoustic sound waves. Usually the peaks are found in intervals of standing waves between record surface and the roof. A clever way to reduce this noise is to use heavy damping material at the roof above the record player. A lid makes the standing wave act on the lid and damps some of the peaks. It will be transmission from lid to the base and shifted in frequency due to the altered standing wave frequency.

Your custom made lid should rest on small soft feet!
 

fpitas

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Maybe tube microphonics will cancel out turntable microphonics ;)

/I'm a bad person
 
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