What's a phonostage, and do I need one?

Help a newbie make the right decisions. I'm almost finished putting together my beginner stereo system. All I have left is deciding on my turntable. I've been looking at the Audiogon discussions and pretty much decided on a Music Hall MMF-2.1 or 5 (I'm leaning towards the 5). My system is powered by an old Marantz 2270 (70 watts). It has a phono jack. One of the discussion threads concerned someone whose phono output was only putting out 1/2 the volume of his other sources. My question is, if I'm using my old receiver, am I going to need to purchase something else on top of what is included with the MMF-5 (or 2.1) for my turntable to sound comperable to my other sources? (my other sources are a marantz CC3000 5 disk changer and an old Nakamichi tape deck.) Thanks in advance.
The lower priced Music Hall TTs have Goldring MM cartridges in them, and will work fine into your Marantz built-in phono stage.
A phono stage/preamp does two things: 1) provide RIAA equalization and 2) provides extra gains for the lower output of cartridges. As a general guideline, you need 30-40db extra gain over line level for high output MM cartridge, 50-60db for high output MC and over 60db for low output MC.

The phono jack of your Marantz should give you RIAA equalization and enough gain for high output MM. As long as you are using a high output MM cartridge, you don’t need to buy anything. But if you want to use a low output MM or a MC cartridge, you will need a separate phono preamp and connect its output to a line level jack, usually marked as AUX in, and not to the phono jack.
In the 1970's, I had a Marantz 2270 receiver, and a Dual turntable (with Shure V15 cartridge). As Sid notes above, the phono stage in the 2270 has adequate gain to handle most moving-magnet and moving-iron cartridges (Grado cartridges), but it will not handle low-output moving coil cartridges (although it may have enough gain for high-output moving coils).

If you don't mind an unsolicited suggestion, it is probably past time for an upgrade from the 2270. While the 2270 was a very good receiver in the early days of solid state electronics, it is by now very dated. Since you are getting a new turntable, and therefore are presumably interested in having a high-resolution audio system, your next step in upgrading your system should be your receiver. Fortunately, there are some good receivers and some excellent integrated amps (if you can live without the tuner) available today. Look through the Audiogon archives for suggestions about receivers and integrated amps.
I agree with SDCampbell
Thanks for the info guys. I'll look into upgrading my receiver soon.
You have a very nice classic receiver and I wouldn't upgrade just because somebody says so. Of course you can do better, but give it a try before spending money needlessly.

One point about relative levels between phono and line level inputs: Most line level devices(like a cd player) put out on the order of 1-2 volts, whereas a phono cartridge outputs a few millivolts, and regardless how much gain you have you will ALMOST always have to turn your volume control up when phono is selected to match the other sources. And some records are cut at a much lower level than others which requires even more gain.

BTW, I have some vintage (70s) marantz separates that still serve me well in a bedroom system
Hi Nicko,
I still run my 1978 Marantz 2285 receiver in a system for my basement. You can plug your table right into the back of your unit. Don't forget to attach the ground wire. It will work just fine! These receivers were unique in that you can also run it as a pre amp if you wish. I recommend you purchase a good quality, used amp, here on Audiogon. This way you will still have all the function /features of the Marantz, but it itself doesn't have to work so hard to create music. I did the same thing and was very pleased with the results. Try Conrad Johnson products, for example the MF2250 or MF2500.