Increasing a Low output MM


Hi I have a low output MM cartridge.  I am looking at a low gain phono stage; a gift.

Is there anyway to increase the output of a low output MM cartridge?

Previous posts have suggested that a SUT will not work due to impedance changes produced by the SUT.  

Any other options, other a new cartridge?

Thanks

mdrone

@mdrone as you have a Soundsmith cartridge you may wish to consider a Soundsmith Phono. https://www.sound-smith.com/phono-preamps/soundsmith-mcp2-phono-preamp.

I’m using an MCP2 MKII with my Zephyr MIMC on my Gyrodec w/ SME M2-9-R tonearm and I’m very happy with it. In all honesty I expected this little SS phono to have a temporary place in my rig. It’s still here after 3 years.


That said, I’’d still like to try a Modwright 90x, @elliottbnewcombjr located a great deal on one. I’m tempted to explore it further.

Now that I look more closely at the cited phono stage -- as others are saying, this Leben RS - 30 EQ is spec’d at only 23.5dB gain, which is way too low, crazy low. I personally avoid MM stages below even 40dB. However, the picture gets much more rosy if we check out Stereophile’s actual measurements of a review unit:

The RS-30EQ phono preamplifier offered a voltage gain of 37.1dB, which is very much higher than the specified 23.5dB but is appropriate for moving-magnet cartridges.

37dB is serviceable. You may still desire for extra gain when using a lower output MM or high output MC (below 2.5mV), but it’s workable. The Hagerman Piccolo I previously suggested has a lowest gain setting of 12dB which would add up to 49dB -- a bit on the high side, but could be beneficial over 37dB in certain cases.

Unfortunately when we read a bit deeper into the Stereophile article the picture gets a bit less rosy again:

The wideband, unweighted signal/noise ratio, taken with the input shorted and ref. 1kHz at 5mV, was modest, at 40.3dB left and 43.9dB right, mainly due to some residual hum components. These ratios improved to 65 and 67.7dB, respectively, when A-weighted.

That’s poor signal-to-noise performance for an MM stage, much less one on the left side of the MM gain bell-curve. Adding an active head-amp gain stage will just make this worse. You might just try the phono stage as-is and see if your line stage + amp gain can cover for it. Given the measured performance of this unit, I think it would perform best with very high output MM’s 4mV - 5mV+. I know the Ortofon 2M series has a very high output level; I don’t know of others as I mostly stick to MC’s.

Stereophile reported high overload margins for this unit, which is good -- that means it should be able to take high output MM's, or medium output MC's plus a 10x - 20x SUT ratio, without distorting. If this phono stage had low overload margins, it would have to be considered a failed product. 

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Dear @mdrone  : Do it you a favor and don't put any $ on your phono stage is, is not woth to do it and a waste $.

Instead invest in a new unit as this one, please read the overall review including the measurements ( important. ):

 

https://www.stereophile.com/content/ps-audio-stellar-phono-phono-preamplifier

 

R.