OK folks, no-one else seems to be motivated to start this so I figure I will. Let's start some turntable basics threads so we can explain the dark side to all those out there who want to know.
Firstly, a disclaimer: I have owned 2 turntables in my life, the current one for 20 years. I grew up with records but I don't think I know that much. So, if you need to correct anything I have written please put it in this thread, I'm not going to be insulted if someone points out where I am wrong. Also, the way I think is that I like to understand the basics so we're going right back to the basics here.
Now, on with the show.
The most important thing I think you need to understand is just how a turntable works. This will involve some explaining and I'm only going to deal with the actual Turntable in this thread (ie: not tonearms or cartridges except where I need to).
The first thing you need to understand is what exactly a turntable (hereafter abbreviated to a TT) is designed to do. To understand this let's look at how a record stores music as opposed to a CD.
A CD stores music as a digital file, effectively a series of ones and zeros - this is the information actually stored on a CD, just a series of ones and zeros. As such you need to convert this back to music when you play a CD (hence the need for a DAC or digital analogue converter).
A record is very different: it stores the actual music, etched into the vinyl disc. For a couple of nice little videos on how records are made and which may help you understand the nature of a record see these: http://www.youtube.com/watch?v=lDmBx4R-Gas&feature=related and http://www.youtube.com/watch?v=8rEmHkumWXI&feature=related
If you turn your amplifier off and listen closely to the needle running through the groove you can actually hear the music.
As such you can make sound from a record very simply, and even make a TT very simply, for example:
Yes this is made entirely of paper and it does work.
In fact, one thing you will notice about this record player is that it contains no electronics. The first phonographs also had no electronics. Look at this one:
You wind it up, the needle reads the groove, sound is amplified by the horn and you can listen to music. Great for stormy nights when the electricity is cut off.
This old phonograph played 78s which are called 78s as they turn at 78 revolutions per minute. One other aspect of 78s is that they had big wide grooves and tended to be made in the 10" (that's 10 inches or around 25cm) size. Since they had big grooves they used big needles such as:
No nude fine line styluses here! Since they revolved so fast and were only 10" they didn't play for long. As such you had to buy a whole pile of 78s to get one piece of music. This came in the form of an album, like so:
We now fit a whole album on one Long Play (yep, LPs) record and this is why they are called albums.
So, what exactly does the TT, as opposed to the tonearm and cartridge do?
Basically all a turntable does is to spin a record at precisely the correct speed (these days 33.3rpm and 45rpm) on a stable platter and form a platform to support the tonearm and the cartridge on the end of the tonearm, which picks up the music from the disc and transfers it to some sort of amplification.
Sounds simple doesn't it? Well it is and it isn't. It is so simple that you can make a turntable out of paper alone. It is also complicated for the reasons outlined below.
Since records have music etched into them and the cartridge must read these microscopic etchings there are a few inherent problems which need to be overcome.
Firstly: how do you turn the platter without introducing some sort of noise from the motor you must use to turn the platter?
This is where drive mechanisms come in. There are 3 main choices:
Belt Drive: this is where the motor is separated from the platter and the platted is driven by a belt. The idea is really an obvious way of decoupling the motor from the platter and varies from TTs which have the motor in the same housing (like mine) and motors which are physically separated from the TT itself, like this:
Idler Drive: Another way of driving the platter is to use an idler drive. This is where the motor runs a small wheel which directly drives the platter. Garrards are often like this and although I was brought up in the mean 1970s when idler drives were considered not very good, however, some of these are very good. I've noticed a number of radio station turntables seemed to be like this. More recently VPI have released an idler drive which turns the outside of the platter.
A couple of idler drives:
How the drive works:
Direct Drive: Wouldn't it be nice though, and possibly more accurate in terms of speed (no slipping belts or idler wheels) if we could couple the motor directly to the platter. If you can get rid of any interference from the motor this is a very good idea. In fact direct drive turntables can be very good, they certainly boast very good speed stability and accuracy and, depending on your opinion, the problem if interference from the motor has been solved to a degree where direct drive turntables are very good. Probably the most famous direct drive turntables are the Technics:
Too long, continued next post
DS
