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Matching Pre-amp Settings for Cartridge

Hello-

I have a Yamaha C-85 Pre-amp. I have a Sumiko Blackbird (High Output 2.5mV) moving coil cartridge.

The Yamaha offers 2 selections for a MC cartridge, they are 100 Ohm and 1K Ohm.

Some of the Sumiko specs are the following: Freq. Resp.= 10Hz - 50kHz, Internal Impedance = 135 Ohms, Load Impedance= 47k Ohms

Question; do I select 100 Ohm or 1k Ohm on my Pre-amp phono impedance selector ?

I have more specs if needed.

Also, on rear of Pre-amp, next to phono jacks, is a red button selector. Manual describes red button as follows: Use this switch to refine volume control with "high output  level cartridges". I assume my cart is high level. Press button in to lower signal from cart by 10 dB, press again to release button & return signal to normal. I have it set to normal. Is Normal correct setting for this Sumiko?

TIA, Robes-

128x128robes
robes's avatar
robes OP
23 posts
 

Thanks for the reply. Well that's interesting. After getting this Blackbird probably 4 years or so ago I used it on the MC 1K Ohm. probably within playing a total of 4 albums My Preamp burned out and I sent it in to be rebuilt. When I checked it out it was definitely to due with these impedance switches.

Took a year to get back and only yesterday have the system up & running. I have the same MC 1K ohm selected & played 1 album so far, no more. Sounded good but still fine tuning adjustments. So glad I asked this question!!

So, my MM choices are as follows: 47 kOhm 330pF or 47 kOhm 220 pF or 100 Ohm ? I don't know what pF is, and no mention of it in the spec book that came with the cart.

Since you used it at a 38dB gain, I'll leave mine at Normal since the only choice is -10 dB-

Thanks so much, Robes

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drrsutliff
858 posts
 

I would try it at 47k ohms (recommended in the carts specifications) and try either of the capacitance (pF) settings of 330 or 220.  Capacitance is much more critical for MM cartridges as a high capacitance can cause a rise in the treble. Most MC cartridges are immune to this issue.  

robes's avatar
robes OP
23 posts
 

Thank you once more for your expertise in this matter. You may very well have saved my preamp from overloading again. If I hear a difference between the two 47k selections I'll set to whichever sounds best.

Have a great day and take care! 

Robes

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