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
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!
Maxgain, I have heard the stories about this being the case, but I have not found it to be true in my situation. A good step-up transformer should not get in the way of the sound at all. In fact, in some ways, it makes a better coupling than going straight into the phono section.

I think that sometimes people don't know how to use them, and then they sound bad. For instance, the loading is different when you load at the transformer, than when you load at the phono stage. Generally the loading at the transformer is much lower than what would be recommended going straight into the preamp. Alot of folks don't know this. In other cases, like cheaper transformers, they don't have loading capability at all, so they won't even have hardly a chance of sounding right. Or sometimes people don't know that there might be a pre-set loading on the transformer, and then they load the phono section too, and screw everything up that way. I think that user error is more likely the reason that some people don't think transformers work well for cartridge step-up.

It's a lot different than an amplifier output transformer. The cartridge signals are so low, that there is no way you're going to saturate that transformer, or roll anything off, as long as it's a decent transformer. And transformers in the right application are a really good thing. Look at the new Audio Note $15k preamps. They have something like 8 transformers in them. Input trannies, output trannies, interstage trannies. Good transformers in the right application can be very good performers.

And if you want to compare with direct input to the phono section, let's face it, you have to get the gain somewhere. If you don't have a transformer, you have to have alot more gain stages in the phono section. That can also lead to signal losses or more noise. So even if the transformer is not perfect, neither are the extra gain stages in the phono section. Also, by having the transformer located close to the pickup, it boosts those low level signals earlier, so their less likely to have loss. Take your pick. I like the transformer for my money.

I'll guarantee that anybody listening to my system is not going to be saying anything about signal losses in my step-up transformer clouding up the signal. This system is crystal clear.
Ok, for all of you "gain heads"

here is the calculator...

http://www.kabusa.com/pregain.htm