Takk KJ, Var en tur i London på tur. Men har fått svar ifra Linn
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]Normally with a line level balanced stage, there are two phases of signal which are equal in magnitude, summed together which doubles the signal level out of the receiver, so 6dB attenuation is applied to correct for the effective doubling in level, this also attenuates the noise of the summation. At line level, balanced is a good thing. The cartridge is single ended, with a cartridge the source voltage into a balanced input is divided into the two phases so there would be no attenuation after the summing stage, the result is the summation noise is not attenuated so the signal to noise ratio is worse for being balanced. When designing the Urika we developed a balanced design but the design proved the theory true and the result was disappointing as summation of the two phases result in an increase in the noise floor which is undesirable. [/FONT][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]We also tried a full differential design, right through the RIAA Equalisation stage choosing to do the summation at the end of the design for an RCA output or keep it balanced all the way to the pre-amplifier. On listening this design was canned as it is fraught with problems and compromises, due channel matching of the gain and equalisation between the phases. The mismatch between left and right simple cause a <0.1dB difference in signal level however <0.1dB differences in equalisation of phases which at some stage are summed together at the pre amplifier resulted in ripple on the RIAA curve which is many times more obvious due to its variations to the signal phase.[/FONT][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]For Uphorik we’ve choosen to use an ultra low input noise single ended design derived from the Urika. however utilising the benefits of an XLR connected for a single ended phono signal. The cartridge is a source, there is a hot terminal and a cold terminal. The movement of the stylus results in a very small current in the coil. This current produces a tiny voltage across the coil. If you assume the coils cold terminal is the reference then all the wanted signal appears on the hot terminal. The job of the phono stage is to boost the wanted signal x1,500 times and apply EQ. The phono stage only knows about its own reference, 0v, and the incoming signal from the cartridge. To minimise losses the reference terminal of the cartridge must be as clean at the cartridge end of the arm lead as it is at the phono stage end.[/FONT][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]In a single ended cable the reference signal, 0v, is also used as the screen of the plug and of the cable itself. The screen acts to protect the inner core signal from noises outside the system, like speaker cables and mains cables, by acting as a low impedance current, I[/FONT][FONT=Calibri,sans-serif][SIZE=-1]noise[/FONT][FONT=Calibri,sans-serif], path for the noise to earth in the pre-amplifier. The cable has a resistance, R, and this therefore creates a noise voltage, V[/FONT][FONT=Calibri,sans-serif][SIZE=-1]noise[/SIZE][/FONT][FONT=Calibri,sans-serif] = I[/FONT][FONT=Calibri,sans-serif][SIZE=-1]noise[/SIZE][/FONT][FONT=Calibri,sans-serif] x R. So the reference of the wanted signal of the cartridge is now polluted by V[/FONT][FONT=Calibri,sans-serif][SIZE=-1]noise[/SIZE][/FONT][FONT=Calibri,sans-serif]. This is a bad thing.[/FONT][/SIZE][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]Using a 3 pin connector, like an XLR, the reference signal, 0v, is treated with the same care as the wanted signal from the cartridge. The screen of the cable and the plug body is kept at the earth potential, this creates a very effective screen, effectively creating a drain to earth for the unwanted noise current that is not connected to the signal reference or the signal voltage itself. A very obvious example of this is with MM cables, with a single ended cable, of you touch the body of the plug you can hear a change in the audio, for the worse, as you act as an antenna for noise which is then injected into the reference signal. Repeat with the balanced cable, not only is the initial performance better but there is no degradation to the performance when the connector is touched. Obviously this isn’t an everyday occurrence but it does illustrate the effectiveness of the screening benefits from the “balanced” arm cable.[/FONT][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]This is why the Uphorik uses XLR connectors as an effective screen for the single ended signal and it’s reference. The difference in performance is clearly demonstrable. The RCA connectors are there for backwards compatibility for customers who are unable to use our “balanced” arm-cable because they are not Linn tone-arms or compatible with our arm cable mounting.[/FONT][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]The term balanced has been used simply to differentiate the cable from a single ended cable.[/FONT][/FONT]
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[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]I hope this helps to clarify.[/FONT][/FONT]