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Acoustic feedback effect on turntable ...
I put a stationary record on the TT and lowered the stylus onto it. I then play Pink noise from the speakers, while recording the cartridge/pick-up signal. This is what I get
Turntable 1 Michell Gyro SE, SME V AT-OC9MLii at 59db gain /200 ohm. No platter mat used,
Then another TT Denon 51F with Shure V15 IV Jico SAS-B at 39db gain /47k added to the plot=blue curves
Let's see if we can tell much in a comparison using 30 second samples, they go by very quickly :) This subject came up in the new AT cartridge thread...
Acoustic feedback effect on turntable ...
I put a stationary record on the TT and lowered the stylus onto it. I then play Pink noise from the speakers, while recording the cartridge/pick-up signal. This is what I get
Turntable 1 Michell Gyro SE, SME V AT-OC9MLii at 59db gain /200 ohm. No platter mat used,
To find out what compliance / resonance is on a pickup, you need to know what the effective mass of your tonearm is, and what it is with the pickup installed. Usually you take the stated effective mass and add the pickup weight. But effective mass is not just effective mass, is the stated effective mass with the arm balanced with or without the pickup going to make a difference. So to nerd out a little about this, I played around with some math and statics and torque.
It turns out that if you add mass to a balanced arm, the arm must be rebalanced and that entails a change=INCREASE in the effective mass, and after a lot of tinkering and checking and some mistakes and finally correcting the mistake I come up with the following formula:
dEM= Increase in effective mass=CM1+(CM1^2+2*H*CM1)/W
Where:
CM1=PU mass or other change in weight
H= Effective mass of the headshell end of the arm, typically 90 to 95% of the stated effective mass
W= Mass of counterweight
Let's take an example with a stated effective mass of 10 grams and add a pickup of 10 g with screws and all, and a counterweight of two hundred grams (which is quite hefty=high end counterweight)
New effective mass is therefore not 10+10=20 but 10+10+1.45=21.45 grams or a full 3.6% lower resonance frequency, (possibly the same % effect on calculated compliance from test plate resonance Hz). If you have a lighter counterweight, for example 100 grams, the addition is twice as much, almost 3 grams. This may be an explanation for those wondering why the resonance frequency was lower than they thought…
For simplicity I assumed a static balanced arm, but with a static balanced arm the effective mass will be slightly less due to counterweight adjustment, can be calculated from static balance equation…that can amount to 0.2 to 0.3 grams …
There is indeed a lot to worry about regarding vinyl reproduction
I will, looks good enough to try it out, Canada was the closest to me and price seems right. I have to confess, btw - Stereophile had an article on the turntables Unitra makes.
Though in my defense, I didn't read the full piece but went to the Unitra website and looked at their products myself, instead.
Haven't found a dealer, from the website of Unitra - that ships the WT-2 or any products from them for that matter, to the US.
I sent an e-mail to Unitra to find out who would be willing to sell and ship. Will take a while longer than I thought, I guess - still on it, though.
Fisher MT-6330 turntable speed stability and internal pictures. Not serviced-, but not bad. in fact close to the spec of 0.035 DIN W&F.
(The visual trend and data is very similar to the new Denon 3000NE=
It is a good 70usd replacement for my 30usd Sony PS-212 as as kitchen bench TT to try out cartridges and stuff.
Next I will service the simple tings myself , clean pots and set speed control and motor DC bias according to service manual
The slow oscillations once per rev are maybe from too high servo gain, but servo gain is not adjustable as it is on the 6250 model
(It is just a courtesy to the thread starter and the purpose of this thread to keep this thread as much as possible as a "database". But of course - the more cartridges measured the better, so it is welcome! But if there are problems that needs to be sorted out, keep it as a new thread or in the Fun... thread)
I totally agree, and didn't mean to clog up the topic. I just don't know if there are problems or not.
It turns out that to fill the topic of the library, a person must be a pro in scripting, audio recording and cartridge building . otherwise you can not understand if you have problems or not.
To all,
Please help in assessing if there are measurement problems with the Nagaoka MP-500. Starting post:
Hana Umami Red from December 2024. Used about 30 hours. Very difficult to get it right - I have done more adjustments on this cart setup than any other cart I have access to. Tracks 50mu (not very impressive) on the old Ortofon test record. Notice the "sparks" above 5k in the FR which add a...
I have seen such problems when using Focusite. Is is extremely easy to mess with the setup, you may think you are recording at 96k but PC is doing it at 48 or the opposite. You have setting in the sound card/ the interface , PC , and recording software for xxkhz , that all have to match. The problem is in the recording process it self so looking at the file may not help. Try to toggle “Allow exclusive control” in sound settings and see if it makes a difference. Try to record everything at 48k , an then 96 again.
Look at the spectrum for the 1khz pilot tone in Your recoding software, REW , or Audacity if you are desperate .?is it at 1khz?
Can you use something else than Focusrite Scarlet as an PC interface?My Solo was so erratic that I gave up using it…it turned out it was the “exclusive mode” in PC sound settings the cause a lot if problems, still do not trust it fully
My tonearm (Moerch) specifies 28 pF for the internal tonearm wire - then I have ≈100 pF for the RCA cable, and add 10 pF for the phono stage connectors getting around 140 pF. The results I get are quite consistent with that figure.
Did Korf specify (measured) values for the tonearm? You should also be adding 10-15 pF for the phono pre. It is never "zero", and can vary some depending on the connectors and the PCB layout.
I have seen such problems when using Focusite. Is is extremely easy to mess with the setup, you may think you are recording at 96k but PC is doing it at 48 or the opposite. You have setting in the sound card/ the interface , PC , and recording software for xxkhz , that all have to match. The problem is in the recording process it self so looking at the file may not help. Try to toggle “Allow exclusive control” in sound settings and see if it makes a difference. Try to record everything at 48k , an then 96 again.
Look at the spectrum for the 1khz pilot tone in Your recoding software, REW , or Audacity if you are desperate .?is it at 1khz?
Can you use something else than Focusrite Scarlet as an PC interface?My Solo was so erratic that I gave up using it…it turned out it was the “exclusive mode” in PC sound settings the cause a lot if problems, still do not trust it fully
All the settings are the same (win and 2i2). I even tried different drivers. At 48 and 96 the graph is the same, but offset within 1dB in places.
By analyzing the Audacity spectrum at a tonal 1kHz.
The only ADC I have is this one.
I have tried 192, 96 with different drivers and 48. the graph is similar.
I have a Shure v15v-mr a few copies. and have nos inserts to them and a sapphire jico. It's certainly light for a Korf, but with the damping brush it gave decent sound results. Maybe I'll try it on the 3012, it's a little lighter. And if the native nos stylus develops humps around 10k, then I and my adc definitely failed ....
I saw another thing. In the script program when it gives the graph data, there is a data skip. But it still plots the graph...
My tonearm (Moerch) specifies 28 pF for the internal tonearm wire - then I have ≈100 pF for the RCA cable, and add 10 pF for the phono stage connectors getting around 140 pF. The results I get are quite consistent with that figure.
Did Korf specify (measured) values for the tonearm? You should also be adding 10-15 pF for the phono pre. It is never "zero", and can vary some depending on the connectors and the PCB layout.
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