Slowly but surely I will create an FAQ here. Bear with me.
FAQ
1. Q: I want to play records. What do I need?
A: You need a turntable, with a known good or new phono cartridge (sometimes referred to as a "needle" or a "stylus", although those are only parts of a phono cartridge), and a phono preamp.
The turntable itself should be obvious. There are lots of new ones being made, and there are also lots of used ones that can work well, and often can be had for very cheap, although not all of the used ones will work well, and will require more care in set-up, as typically, when you buy a new turntable, it will come with the phono cartridge already set up and optimized.
The phono cartridge is what actually contacts the record. It is mounted on what is called the "tonearm". The majority of turntables come with a tonearm, but not all. However, someone buying their first turntable should ALWAYS buy a turntable that has a tonearm already. The cartridge has a "stylus" (I don't like the older term "Needle"), and this is the part of the cartridge what actually contacts the record. These are subject to gradual wear. Depending on the maker, they will last 1,000-3,000 hours. If you buy a used turntable, and you do not know the age/wear of the stylus, you need to buy a new one. A worn stylus can ruin records.
Phono cartridges have to be properly installed on a turntable and there are several important parameters here that I will discuss later, but the most critical of these by far is the vertical tracking force. The cartridge must be balanced on the tonearm so that it tracks with the right force (measured in grams). The exact process will vary from turntable to turntable, but I will address the basics later.
The phono preamp takes the very low voltage from the phono cartridge and steps that up to line level. Many modern stereo preamps, surround processors, integrated amps, and receivers do not have a built in phono preamps, although some of them do. Almost ALL preamps/integrateds receivers built prior to 1985 does in fact have one. It's almost universally labeled "phono", although on modern units it may be labeled "turntable". You cannot plug a turntable directly into a line level input like you would use for a DAC and have it work. It will not. You must have a phono preamp. Decent phono preamps can be purchased for as little as $50, although better units are much, much more expensive.
You need a phono preamp that will with your cartridge. Most of the less expensive cartridges are "Moving Magnet" (MM), which are high output. The other major kind are "Moving Coil" (MC), many of which are low output, and require a phono preamp that will accommodate a low output MC cartridge. There are other considerations here, but again I will table those for now.
2. Phono Cartridge Alignment
OK, so now you have your turntable working, and you would like to fine tune it. There are a bunch of important ways in which one can get a cartridge dialed in. There is an excellent explanation of these here:
http://www.deadwaxcafe.com/vzone/cartalign.asp
The most critical of these is VTF. You can really screw up your records and or cartridge if you don't do this. Only your turntable manual can really give you the complete instructions here. If you don't have the manual, do to vinylengine.com - they have a huge number of manuals for download.
The basic method of adjusting VTF involves moving the "counterbalance", which is the weight at the back end of the turntable, so that the cartridge tracks the record with a certain amount of downward pressure, measured just like weight, in grams. The most accurate way to measure this by far is with a stylus force gauge. Some of these get expensive, but they do not have to be.
For many older turntables, the tonearm was actually designed such that the tracking force could be set in a simpler way. If your turntable has a counterbalance that has numbers on it, than the simpler, albeit less accurate, method is to turn the counterbalance such that the arm basically "floats" like a balanced see-saw. Be VERY careful when doing this to have the cueing UP so you do not damage the stylus! Once balanced, first rotate the small plastic piece with the numbers (NOT the whole counterbalance) so that it is set to zero. THEN rotate the counterbalance to the number corresponding to the recommended tracking force per your TT's manufacturer. Note that if you do not have a tonearm designed for this type of adjustment, you MUST have a stylus force gauge to set VTF, and you CANNOT just "guess" at this.
If your VTF is a little too low, the sound may be bright; if the VTF is too high, the sound may be dull.
Most turntables also allow adjustment of antiskate. You also need to adjust that, which for many turntables is simply turning a knob to the same number as the VTF is in grams. Some are much more complex and actually involve little hanging weights. Again, you will need to refer to the manual. If the anti-skate is set too high, you can get distortion in the left channel, or you may hear the soundstage skew to the right. Conversely, If the anti-skate is set too low, you can get distortion in the right channel, or you may hear the soundstage skew to the left.
Zenith angle and overhang are also important (and are both related to where the cartridge sits in the tonearm). You need an alignment tool for this, or a specialized protractor. My favorite alignment tool is the Mobile Fidelity Geodisc, which is fairly inexpensive and very easy to use.
Here is a somewhat long but very thorough and helpful video on turntable basics and set-up: http://www.youtube.com/watch?v=CnskL8Pe6fk&feature=youtu.be