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

You need a linear amp with added gain - a head amp. The Marcof PPA-1 will work! Battery-powered! I have one for use with low-output mc cartridges. Some Grado cartridges have 1 millivolt or less output. 

Actually not if you’re feeding an MM phono stage that provides the RIAA correction. But I agree it would be nice to know the name of the cartridge: Input impedance would have to be tailored to the cartridge specs.

the cartridge is a soundsmith Zephyr MK iii.

Output is 2.40 mV  Suggested Gain is 38-44.

The phono stage gain is only 28

Dear @mdrone  : Which phono stage do you own? , normally a MM phono stage comes with 40db gain.

 

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

I’m thinking, set yourself up for future MC cartridge while you solve this problem

This seems to be a versatile unit, I’m sure there are others

 

Pro-Ject A/D Box S2 MM/MC Phono Preamplifier

https://www.audioadvisor.com/pdf/Pro_Ject_AD_Box_S2_Phono_User_Manual.pdf

 

 

mdrone

I am using a Tavish Design Adagio with a Soundsmith Carmen II cartridge with an output voltage of  2.12mv ,  the MM ( MI ) gain is 44db . 

I was unsure if the gain was enough when I switched from a Grado with an output of 5mv since I am going thru a passive attenuator .  If you think that 44db is not enough I believe that Manley makes a phono pre that is adjustable up to 50db .

@mdrone  : Thank's. According the real time measurements made by J.Atkinson in theory the true gain is a little over 37db so you don't have to have a problem running  your cartridge other that maybe a higher than normal noise levels but the critical issue with your unit is that its RIAA accuracy is really poor and goes against the quality levels that your cartridge can shows:

 

https://www.stereophile.com/content/leben-rs-30eq-phono-preamplifier-measurements

 

R.

 

Paradox phono-30 amplification is done via a pair of LSK170 JFET to providing 30dB gain and an external plug for loading your cartridge with any value resistor.

 

You would need a head-amp with flexible loading and gain options. The Hagerman Piccolo is perfect for this, and not too expensive either. The only potential hang-up is it lacks capacitive loading options, though technically you can play with cables for this. 

What is the gain of the line stage that you are using? You should add that to the 28db gain of the phono stage!

+1 for yogi and mulvie. No self-respecting MM phono stage would offer only 28db gain, is an editorial opinion. But if you love it, and if your linestage doesn’t help enough, add an upfront gain stage. Not a SUT.

If you are considering the Marcof, I would really recommend the PPA2 over the PPA1. More load options,better parts.  Not sure but we may still have some new. I would have to get by Ed's, but I believe we a a couple 

If you're the patient type, keep a lookout for a used Herron VTPH-1MM. 44dB gain.

@mdrone 

The problem is that the Leben has abnormally low gain. Most MM phono stages offer around 40db of gain.

I have had the Leben in my system and quite frankly it is quite vague - not worth the money in my view. Even a cheapy Soundsmith phono at around $1k was significantly better. 

My suggestion would be to get another phono stage or if you have the Leben, sell it and use the money for another phono.

@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.