Highest output MC for Soundsmith MCP2

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farmstar72
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Highest output MC for Soundsmith MCP2

Post by farmstar72 » 12 Jan 2019 03:57

Hi,
I have a Soundsmith MCP2 phono preamp with 62db gain. What would be the highest output cartridge I should use. I'm looking for the mv value, not a cartridge recommendation.

Thanks,
Scott

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Re: Highest output MC for Soundsmith MCP2

Post by DeepEnd » 12 Jan 2019 17:41

Rather depends on two things -

One - the input sensitivity of the line input on your amp this would give a minimum figure

Two - the max output of the phono stage (8.3 V? from specs) combined with the amount of headroom you want to keep this would give the maximum figure.

However I did see an interesting note in the specs " Input overload levels for output clipping or non linearity - MCP-2 ~~~~ 20Hz - 1.4 mV; 1Khz - 5.3 mV; 20KHZ - 35 mV with input load set to 200 Ohms".

For One as an example using the 250mV sensitivity figure from my MF amp combined with the 62db gain (~x1,259) would give 199uV (0.2mV) as a minimum figure [250/1259=0.1985702].

For Two using the 8.3V and 62db figure gives max input of 6.6mV not the 5.3mV figure noted so this lower figure might be the transformers starting to saturate rather than the output stages starting to clip. If we said that you wanted to retain 20db of headroom (so you can play +18db test tracks or hot 45rpm records etc) this brings the maximum figure down to 0.53mV cleanly or possibly 0.66mV and and accept a 18db headroom clean at 1kHz and small amount of non linearity on extreme limits at +18 to 20db. Please note that at 20 Hz you have even less margin for headroom as the figure drops to +10db from a 0.53mV cartridge which is probably not a real issue in practice but does also point to transformer saturation as the practical limit.

Having looked at this I now know why my phono stage is only 60db gain with 11.5V max output as this would give 26db of headroom for the same 0.53mV output cartridge.

farmstar72
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Re: Highest output MC for Soundsmith MCP2

Post by farmstar72 » 12 Jan 2019 21:56

My integrated amp is a Primaluna Classic with an input sensitivity of 285mv. Where does that leave me?
Thanks in advance,
Scott

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Re: Highest output MC for Soundsmith MCP2

Post by DeepEnd » 12 Jan 2019 22:56

Minimum voltage needed 0.23mV, maximum 0.53 mV (or 0.65mV as a outside possibility)

farmstar72
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Re: Highest output MC for Soundsmith MCP2

Post by farmstar72 » 13 Jan 2019 00:44

Ok, the cartridge that has me wondering is a Lyra Dorian in need of a retip (.6mv). So I'm not sure I should invest in the retip if it's on the fringe like that.

Thanks for the info.
Scott

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