Will our MC for the festivities gain the stage?


Those of us who own preamps with phono stages are familiar with the phrase, “will handle MM cartridges and most MC cartridges”. The word “most” becomes critical when considering many of the low-output pickups available. My Kora Eclipse, for example, has separate MM and MC inputs and the MC stage is rated at .4mV/100ohm with a gain of 55dB. At what point is that 55dB gain insufficient to handle EFFICIENTLY a very low-output pickup? .5mV, .6mV? I know that it does depend upon actual output of the pickup and there are no hard and fast rules. I was given the following general guidelines some time ago which I post below. Does this seem like a good “rule of thumb” or is someone prepared to give it the finger, instead? Thanks.

0.2-0.5 mV needs 63dB gain
0.6-1.9 mV needs 50dB gain
2.0-5.0 mV needs 37dB gain
4yanx
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Yes, Marty, I had had been in e-mail discussions with Tom with respect to the Shelter pickups, among others. I posted here because I thought others may have the same general issues.

I had come to some conclusions, based on faulty info I had received stating that the gain for the MC phono section in my Eclipse was 70dB. I have since found out from Kora that the actual rating is 55dB. As such, the suitability of the Shelter came into question. I had not figured on the "additive" effect of the line stage gain and have a message in to Kora to determine this specification (the manual only provides line input S/N of 112 dB).

If the gain of the line stage is in the 20dB range, added to the 55dB of the MC phono stage, I am assuming that things should be hunky-dory, given the .4mv/100ohm specs of the MC phonostage in conjunction with the attributes of the Shelter.

Does ANYONE have any thoughts as to whether the general guidelines for gain posted above have any relevance?
4yanx, I think the table you were given is an acceptable minimum for those who strive for lowest noise in the phono stage. I myself would want even more gain if the noise floor of the phono gain circuit was up to it. Matching gain, impedance and noise is very important early in the signal path. Small imperfections in the source end are amplified and add up to big imperfections in sound. Please correct me if I am wrong but I reckon it make better engineering sense to use a low noise high gain phono stage designed to add little noise of its own and that of the MC cartridge (thermal noise) than relying on a high gain line stage which would amplify the noise of a low gain phono stage. Thus I prefer less gain (<20db) in the line stage of a preamp. With (SA)CD players and tuners easily putting out 2+ volts, more than 8 db in the line stage just isn't necessary to drive most amps. Perhaps an adjustable gain setting in the line stage is a sensible option.
One might also consider the system as a whole when trying to determine "sufficient gain." Obviously, the cartridge output, phono gain and pre-amp gain are important. Remember, your amplifier input sensitivity & gain, and speaker sensitivity will also play a role in what is perceived as sufficient source gain in terms of spl. Also, keep in mind that most volume controls (trimpots) will sound better when used in their upper regions as you are removing more of their conductive material from the direct signal path. Enjoy.
Twl, don't most transformers negate the performance advantages of low output MC's. I know that their are some out their that must be good. I was told that the Jensen transformers made in england are very good but where would you get one?. I have experience with mostly old stuff like the Varion(I think that's how it is spelled) and some old ortofon transformers.I never liked what they did. Bring me up into this century please!