Cartridge Imedance

[Hari Iyer]

After Selvin's EPC270C cartridge was received the first thing i did was to measure the R, L & C values using my LCR meter. I noted the following,

Left channel
R = 405 ohms
L = 435mH
C = 6.6nF

Right channel
R = 420 ohms
L = 492mH
C = 10nF

I was not much worried about the R & L values, but the capacitance of this cartridge looks a bit on the higher side. Compare the one with Ortofon cartridge is as below,

Left Channel
R = 740 ohms
L = 495mH
C = 82pF

Right Channel
R = 745 ohms
L = 492mH
C = 77pF

The Ortofon cartridge tolerance is also quite good in this respect.

To answer my curosity, i also tried to measure my Dual cartridge for one channel to find out more,
R = 700 ohms
L = 504mH
C = 3.2nF

In the dual cartridge too the capacitance is on the higher side.

My worries - if the capacitane is on the higher side, the resonance peak will fall in the 2KHz to 10KHz range which will be very peak in the midrange.
To address this i am thinking of adding a 100pF capacitor in series with the phono input to reduce the input capacitance to around 98pF instead of the 6.6nF.

Will this solution work - as i am blocking the inductance and resistance of the cartridge.

With my current Ortofon cartridge, the input capacitance including the cables + RCA is around 136pF which is quite okay.

Selvin has confirmed that the cartridge sounds great and there is nothing noticed SQ wise.

Suggestion / solutions welcomed.

 

[jls001]

@Hari: try the cartridge and hear how it sounds. Vinylengine database gives very minimal info about the 270C. It's silent on recommended C loading or R loading.

After hearing it if you feel the mids are peaky, you could try reducing the R loading to reduce the amplitude of the peak. Series C ought to push the resonance frequency further up the spectrum, but could also lead to added brightness.

 

[Hari Iyer]

@Hari: try the cartridge and hear how it sounds. Vinylengine database gives very minimal info about the 270C. It's silent on recommended C loading or R loading.

After hearing it if you feel the mids are peaky, you could try reducing the R loading to reduce the amplitude of the peak. Series C ought to push the resonance frequency further up the spectrum, but could also lead to added brightness.

I tried simulation of this cartridge using PhonoLCR and it gave me a nasty peak at 2.5KHz and roll-off quite steep after 8Khz.

Changing the capacitance to 98pF made the response flatter. But again I did not modify the L or R which is wrong as these will now become infinite.

I have not yet purchased the stylus and shall do so in a month or two.