Fun with vinyl measurements

[Balle Clorin]

I think people , including me , forget to correct for FFT gain…when doing amateur measurements.

 

[Balle Clorin]

Here is my Measured effect of MC load on. RIAA signal level and noise, no SUT used here. 47k load have much more noise 5+dB so I did not include it…
Mint test record Toshiba LF-90001, ref level 3.5 cm/s seems to be lower than other reference records, 2.5db lower than CBS 3.5cm/s same 45 degree modulation.

In the range 10-200 ohm with my AT OC9MLii 200ohm gives highest signal level, highest SNR. Since I have already shown that the frequency response is NOT affected by MC loading, there is no point in using a lower load than 200ohm. The cartridge internal resistance is 11.6ohm …

 

[markstein]

Very interesting, thank you for sharing.

Surprising that SNR @47kOhm is worst. I would have expected the best SNR with highest input impedance as the insertion damping (correct term?) gets lower with higher input impedance, meaning the signal level gets higher.

 

[markstein]

Off topic - @Balle Clorin: How does the AT OC9ML II compare to the AT PTG33 II? Do you have both?

 

[Balle Clorin]

I was also surprised at the 47k result.
I have both PTGii and OC9MLii

I have posted sweeps in the cartridge library thread. My OC9 have a 9khz kink in Left channel that is isolated to my sample, PTG has a shorter and steeper cantilever that should track better(lower effective tip mass ), but several published sweeps show an anomaly on a particular test record, not on others. It seem like a bump in the record triggers some resonance or movement that cause a wavy frequency response . If it had not been for that the PTG could be the best cartridge..
I cannot hear anything bad on either PU, PTG is lower under 10k with a less pronounced peak above, OC9 is flatter below 10 and with a higher peak.
So PTG may sound a bit more relaxed or polite than OC9 depending on your age, OC9 sounds more detailed for older ears.

Otherwise both are very good cartridges for the money. OC9MLii has better specs than the new XML family, but the library here shows superb data, better than spec . There is a slight difference in compliance between the two.

Due to the sweep anomaly of PTG I will not by another, but rather go for a OC9XML or maybe a Shibata /Fine line version just to get that experience , and possibly less critical setup, but technically ML is the best there is.

 

[Thomas_A]

Extracted the audio and compared

Not much difference
View attachment 389623
View attachment 389624


Start in groove
View attachment 389627

The OMA seems to have a horrible tonearm/cartridge combination boosting both vertical/horisontal resonance (since it is not perfectly out of-phase, I would think that the arm goes wild here); even though the vacuum table seems to take care of flattening the warp. Another very "praised and unique new tonearm" that Fremer tested also shows horrible LF noise (guess which one?):

Fun with vinyl measurements

You mean a test records 3150 Hz? This is not what I mean to test though. I just mean testing speed with the load of the arm/cartridge friction. Any LP will do. sorry... you are true...": speak to fast"" ( just funny too compare too in real time two methods)

www.audiosciencereview.com

For those of us that don't have vacuum hold-down to flatten records, I wonder if you or someone else have tested the impact the Michell clamp and a concave turntable mat? Any measurable effects of noise and speed?

 

[Balle Clorin]

I have the Michell clamp on my Gyro SE, and the flattening of the record it does makes a measurable difference, both om wow&flutter and low end rubbish

 

[Thomas_A]

I have the Michell clamp on my Gyro SE, and the flattening of the record it does makes a measurable difference, both om wow&flutter and low end rubbish

Do you use it always or only sometimes? Not sure if you have published some results in this thread. Ideally one should use a slight concave mat as well. And there is one I looked at, the BR12. It is 5 mm thick and slopes 1 mm. Rather heavy and expensive. Or using the opposite way by a felt ring around the spindle and clamp the record the other way. A bit complex and azimuth might change half a degree or so.

 

[Balle Clorin]

Always, I read that the Gyro plattervis slightly concave, but I have not noticed it. anyway the record itself have thicker edges at label and edge.. so The Michell clamp uses a felt pad too at the spindle, if not you will just force the outer rim to lift and make things worse…

 

[Thomas_A]

Always, I read that the Gyro plattervis slightly concave, but I have not noticed it. anyway the record itself have thicker edges at label and edge.. so The Michell clamp uses a felt pad too at the spindle, if not you will just force the outer rim to lift and make things worse…

Does the felt pad come with the clamp and how thick is it?

 

[Balle Clorin]

Yes felt pad is part of it, came with my second hand TT

 

[Thomas_A]

So quite thick. So felt pad around spindle then record and last the clamp. It seems to me that the record would slope about 3 mm from center to outer rim if the pad yiields 1 mm? Or does it yield more than 1 mm?

 

[morillon]

View attachment 393135View attachment 393136View attachment 393137View attachment 393138
Yes felt pad is part of it, came with my second hand TT

vpi too
(clamp to aim and rubber washer)

 

[Balle Clorin]

No not really any visible slope, the felt is compressible, and the plates has a recess in center, it just pushes the record well down and flat, much more than any weight can do.

 

[morillon]

The old VPI of the annees is 90.. (seem this principle on recent ones...) The aspect view is little more effective and simple to clamp for serrage ( for me).....

 

[morillon]

It's still a hell of a mess... which always invites us to put things into perspective a little more ;-)

The iFi Micro iPhono - and Why All LPs Were Not Created EQual - Positive Feedback

Whatever the settings, the iFi Micro iPhono was notably quiet and smooth, free of edge and grain-but it wants an extended burn-in to be at its best.

positive-feedback.com

 

[Balle Clorin]

Not sure what you are asking..

 

[morillon]

Not sure what you are asking..

sorry I removed my pointless blabla ;-)

 

[Thomas_A]

I think I will go with a Pi instead. I have a few records with large warps and a bunch with smaller warping that perhaps could be perfectly flat after baking them in Pi. I want the simplest possible routine when playing records and it is easier to center LPs with just a felt mat.

 

[undeakyetonde]

It is easier to center LPs with just a felt mat.

What do you mean by that?