Hi Hans
Thanks for replying.
Regarding the setup for inductance measurement using the resonance method, all is OK in your LTSpice model. So it’s with the result. 5.7kHz is the resonance frequency. Why do you think it is wrong?
I will have another run with the same setup and a larger capacitor, to see if at low frequency there is a hint of inductance change with signal level.
Now about the cartridge self resonance case. You use a different setup from those I’ve used (attachment).
Although freq difference is alarming, I will run a test with you setup
Can you please re-post the equations for this?
George
Thanks for replying.
Regarding the setup for inductance measurement using the resonance method, all is OK in your LTSpice model. So it’s with the result. 5.7kHz is the resonance frequency. Why do you think it is wrong?
I will have another run with the same setup and a larger capacitor, to see if at low frequency there is a hint of inductance change with signal level.
Now about the cartridge self resonance case. You use a different setup from those I’ve used (attachment).
Although freq difference is alarming, I will run a test with you setup
Can you please re-post the equations for this?
George
Attachments
Hi George,
I have added some information to your images.
For the two images at the left you should know the input capacitances, because they are part of the equation.
V(r) is a real voltage and V(a) a complex voltage. You should know magnitude and phase in relation to V(r) to convert this into re and im.
Same is true for the set up at the right.
V1 is real and V2 should be converted into re and im from magnitude and phase in relation to V1.
The letter W used in the equation stands for 2*pi*freq.
Hans
Attachments
Could also be different oscillators a swept one vs a fixed one, but it is easily seen on a time domain plot with the fundamental removed. Maybe you could post 5sec or so of the 1kHz tone.
Even can see it with Audacity.
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Interesting to use 4.7k driver. I think that the results are more accurate using the actual cabling and signal levels on the cart closer to actual levels playing an LP. The lower signal level shows stronger capacitive loading effects.
I am scoping the cartridge output from the preamp.
I am scoping the cartridge output from the preamp.
Are you still banned at VE? There are some pics there, but if you don't have image view ability I can email them if interested.
Well, here it is (again resonance method for measuring inductance, this time with 2.12uF Cref)
At low frequencies, inductance does go up with signal level for this cartridge (Ortofon Super OM10), just like Hans plot showed in post #1355.
George
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Similar to cored inductors in equalizers, this problem unfortunately is fully multi-dimensional. You must repeat the measurements over a range of frequencies and levels in a full matrix.
Since the last upgrade you can only see images when logged in. I'll pull them off and post them here. Sure the others wont mind a small drift off topic 🙂
Edit: got it done. The concorde version is so rare a good shot isn't available, but the MC200 version is owned by a VE member in Denmark.
Edit: got it done. The concorde version is so rare a good shot isn't available, but the MC200 version is owned by a VE member in Denmark.
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Last edited:
Here is one for left channel; peak 1000 Hz is -16.7 dB, 2nd harmonic at -72.1 dB, 3rd at -74.4 dB. So difference is 55.4 dB for 2nd harmonic and 57.7 for the third.
But I found out why there are differences; when I split stereo tracks and measure left, I get -22.1 dB for the 1000 Hz signal and -68.0 for the 2nd harmonic, -79.7 for the third. Difference 45.9 dB and 57.6 dB, respectively.
Don't know why, I thought the FFT took the left channel by default when in stereo, but now I don't know how it calculates.
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Thanks. I would love to have the Concorde version. I don't know how the MC200 works - OM-style, but an MC- this one must be fixed in the arm?
MC 200 was a replacable MC built into the OM/concorde body, so the tip had the generator in it. MC 100 and 200 cartridges . the MC200 do come up for sale now and again and I do get tempted but resist as I really have no need for any more cartridges right now.
Scott, right. It is indeed a complex subject.
Hans has adequately displayed the effect for the Ortofon Super OM10 in posts #1294 and #1355.
I was only curious to spot check myself with a different method.
I will repeat the check on Bill's Dual ULM65E (Bill says it is a re-branded Ortofon OM10) and then I will try to test THD vs signal level on the electrical part of the cartridges.
George
Bleep-bleep-bleep
George
All right. Splendid job I have done 😀, so there has to be at least one serious mistake somewhere
The # 5 attachment in my post (#1394) has all the signal levels wrong.
Please consider it non valid and refer to the new attachment here.
Signal levels have been verified by re-measurement and are properly inserted in the spreadsheet.
Horizontal axis at the diagrams has been adjusted to suit the lower signal levels.
George
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Bill I have written a sw code to watch your behaviour here.
Anything in your posts containing “buy” OR “purchase” OR “I’m intrigued to [verb] this” OR “expand my collection” AND “cartridge”, will trigger an audio/visual alarm on my pc, send a warning SMS on my mobile and energize the mattress shaker in my bedroom.
George
Now I understand why Bill sent all his Carts to me, he is simply removing all evidence that can be used against him, preventing your mattress shaker coming int action.Bill I have written a sw code to watch your behaviour here.
Anything in your posts containing “buy” OR “purchase” OR “I’m intrigued to [verb] this” OR “expand my collection” AND “cartridge”, will trigger an audio/visual alarm on my pc, send a warning SMS on my mobile and energize the mattress shaker in my bedroom.
George
Hans
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