Cartridge Loading for a phono pre amp
Hello,
I have recently acquired a phono pre amp recommended by Michael Fremer. It is “THE VINYL”, from QHW audio, Spain. It got a great review. I have a Benz Micro Glider rated at 1.1MV. I have no idea how to set the dip switches for MC Load impedance for this cartridge. The options I have are as follows: 47K, 1K, 560R, 470R, 100R, and 47R. I have a solid state amp and pre-amp, and also have a sub that I use, rarely.
Any advice would be most appreciated!!
Dear @fundsgon : So you agree that 47k is standard for LOMC since appeared as is in the MM/MI cartridges ? How on earth did you infer that I agree that 47k is standard for anything? Certainly not in my previous post. |
If JCarr really said this, then he isn't aware of how balanced operation works. A dynamic microphone is a balanced source because its floating. An Ampex 351 tape machine has a balanced output because the secondary winding of its output transformer is floating. My Neumann U67 microphones are a balanced source because their output transformers have a floating output. Atma-Sphere was the first company anywhere in the world to offer balanced line components for home stereo use. The equipment supports the balanced standard, known as AES48. In a balanced connection, ground is ignored- its not part of the audio signal. This is why in a phono connection with RCAs, you have that weird ground wire that no other single-ended source seems to need. This is because you have a balanced source that is being fed to a single-ended input, and you have to do something with the ground, which otherwise isn't connected to the audio signal, but is its shield nevertheless- that being the tonearm tube of course. More on this topic: http://www.atma-sphere.com/en/resource-why-balanced.html Note in this article about halfway down the phrase
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Dear @fundsgon : Maybe the " grado gold " be really good in other regards but certainly not in this one.
Now give me a help for this @cleeds too: there is a man that in the last 5-6 years was spreading false information about the same issue and it's not only false but a lie. The spreading information was and is not only in Agon but on other internet audio forums. Spread the information with no real foundation and as here I gave and give examples that said almost all phono stage active high gain phono stages are designed with way different characteristic about. JC3 phono stage designed but famous J.Curl and reviewed by MF:
"the loading for moving-coil cartridges is limited to 100 ohms or 47k ohms, with 47k ohms also for the moving-magnet input. Curl believes that the vast majority of MC cartridges are suited for 100 ohm loading, and I concur. If you don't like that, leave it wide open at 47k, which I believe is almost never correct. "
CH Swiss 4 chasis phono stage ( around 95K dollars ). It comes with what CH named the Wizard. Please read:
" In illustration using a very low output cartridge vs a very high output cartridge connected to the Current Input vs Voltage Input on the P1
My Sonic Lab Ultra Eminent BC: 0.6Ω output 0.29mV
Voltage Input: At 0.29 mV, the Wizard determined the optimal gain level at +70 dB of gain. This setting has audible hiss coming from the speakers at 30% volume without any record playing. On careful listening, the gain level was sufficient. Optimal loading was determined to be 180Ω by the Wizard.
Current Input: At 0.6 Ω, the Wizard determined the optimal gain level to be I/V + 20 dB, but based on listening test I preferred a much lower setting of I/V + 5 dB.
According to Ohm's Law where I = V/R, Current = 0.29 / 0.6 = 483 Micro Amps, a very sufficient level of gain based on the low impedance of the cartridge.
Clearaudio Goldfinger Statement (GFS): 50Ω output 0.9mV
Voltage Input: At 0.9mV, the Wizard determined the optimal gain level to be 70dB of gain on the Voltage input. On listening test, I preferred +60 dB of gain, a much lower setting. Optimal loading was determined to be 330Ω by the Wizard.
Current Input: At 50Ω, the cartridge required IV+ 20 dB of gain.
According to Ohm's Law where I = V/R, Current = 0.9/50 = 18 micro amps, the GFS's high input impedance resulted in a very low level of gain regardless of the Goldfinger's output of 0.9mV, which is relatively high for an MC cartridge.
The P1 "Wizard"
As with all voltage amplification circuits, proper impedance loading is crucial to the resultant frequency response of the audio signal. The P1 provides a selection of five hundred resistance values from 20Ω all the way to 100kΩ in logarithmic increments; you'll have steps of 1 ohm in the 20 Ohms range and the gaps between the values are increasing as you go upwards. The steps around 24k Ohms or above, are at 500 ohm increments. While most manufacturers will tell you to "go with your ear" while choosing the right loading, CH has developed an approach based on scientific measurements. The P1 is built in with an ingenious two part "Wizard" which will determine the optimal settings for GAIN and MC loading resistance automatically.
The P1 comes with a test LP designed to work with the P1's internal distortion analyzer.
How reliable is the Wizard? I compared the results generated by the P1 versus the results from my own proprietary test LP and analog setup software currently under development. We arrived at the exact loading choice with a difference of only 10-20 ohms. Assuming we are relying on each other as the reliable benchmark, the results are close enough to be called scientifically verifiable! "
Swiss made too and expensive Dartzeel 18NS. MC load impedance up to 300ohms:
The phonolinepreamp in my room/system comes by default with 100 ohms. Levinson, Krell and the like have the same kind of load impedance characteristic.
We audiophiles have a lot of evidence about the LOMC cartridge loading. So, all those very well regarded designers are wrong? |
