Turntable Basics Part 1 - The Turntable

[davidsss]

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

[davidsss]

Continued . . .

Well that's enough for drive systems. But, wait a minute, I walk around the room and the record skips, this causes scratches and I can also hear footfalls through the speakers. What's the story?

Well, we need to isolate the TT from outside influences as well.

I know, I have an idea, why don't we put the TT on springs, better yet, why don't we just put the platter and tonearm on springs and leave the rest inside the plinth? Hey, there's an idea - an idea which you can see in many TTs, notably the Linns and Thorens TTs. These are called suspended turntables, you can see the suspension here:

This is from a Linn.

But all that adjusting of springs and getting it all right is a pain. Isn't there a better way?

The other way is to build the turntable with mass. In other words make it heavy enough that it does not transmit vibrations. The materials used can be very esoteric in this approach too as TT manufacturers seek to isolate the TT from outside vibrations. There would be too many TTs using mass to list but some rather interesting ideas have been used such as making a platter out of slate, massive stands and just massive turntables. Here is one of my favorites:

If anyone has a spare one of these please send it to me

Lastly, that platter has to turn and has to be supported somehow. The solution to this is for the platter to sit on a bearing. Now, this is an area I know next to nothing about. Most TTs have some sort of metal bearing such as this:

This is the bearing in it's housing on the TT.

The bearing pulled apart.

And, nicely cleaned up ready for clean lubrication. These are actually pics from a thread on the Vinyl Engine and the TT is the same model as mine (not bad for 35 years old hey!). These pics gave me the guts to service my bearing, and a very successful job it was.

Some TTs use more exotic bearing such as a magnetic bearing and variations on the above. The important thing is that the bearing be silent and move without drag. As such one of the big differences between a cheap turntable and a megabuck TT is the bearing as it is expensive to make a bearing which can meet the criteria for silence and free movement.

The main and really only job of the bearing is to support the platter while it is turning. This is not as easy as it sounds as some TT platters can be very heavy to aid isolation and reduce interference.

I'll leave it there. As you can see the actual turntable is a very simple thing, unfortunately it may be a simple concept but it can be very complicated to get it right.

I hope this helps some of you out there. See, it's not really all that complicated!

DS

[Mike.L]

excellent effort David

[davidsss]

Couple of things I probably should add.

As far as I can tell belt drive is now the most common drive system for TTs. However, there is one big exception, DJ turntables are almost invariably direct drive. Direct drive offers some compelling advantages for DJs such as being able to vary speed quickly and easily (you often see sliders up the side of the TT) and, with the use of a slip mat, you can stop the record on the mat while the platter keeps moving to "scratch". Also direct drives are quite rugged.

I would also say (although this may be my own biases showing) that mass loaded TTs are now more common than suspended decks. Linn and Thorens certainly still make suspended decks but just about all the other brands seem to be mass loaded with no suspension.

DS

[waricle]

good on you David!

Good info!

[Guest Muon]

Nice work David, is this getting stickied?

[Roberts]

Excellent read, David. Thank you.

[Jake]

How do we give gold stars? This deserves a whole jar of them. Great stuff David. It would be nice though to have it stickied without all of our comments through it.

Cheers,

Jake

[Keith_W]

Thanks for posting David I had a chat to 2sheds when he mentioned that you guys would be making a collaborative post. Unfortunately, can't sticky this thread, because I believe there will be 5 parts. I'll create one thread, with a link to this thread and any other subsequent threads or feature articles others may want to write, and sticky that. Otherwise the forum will be cluttered up with stickies. Don't worry, your work won't get lost!

[Aslan]

Excellent post David...............a great resource for those wanting to return to the Dark Side.

[Nostro]

Great effort David & am looking forward to your next instalments & how far you care to delve into the Dark Side.

[Alan Monro]

Continued . . .

Well that's enough for drive systems. But, wait a minute, I walk around the room and the record skips, this causes scratches and I can also hear footfalls through the speakers. What's the story?

Well, we need to isolate the TT from outside influences as well.

I know, I have an idea, why don't we put the TT on springs, better yet, why don't we just put the platter and tonearm on springs and leave the rest inside the plinth? Hey, there's an idea - an idea which you can see in many TTs, notably the Linns and Thorens TTs. These are called suspended turntables, you can see the suspension here:

This is from a Linn.

But all that adjusting of springs and getting it all right is a pain. Isn't there a better way?

The other way is to build the turntable with mass. In other words make it heavy enough that it does not transmit vibrations. The materials used can be very esoteric in this approach too as TT manufacturers seek to isolate the TT from outside vibrations. There would be too many TTs using mass to list but some rather interesting ideas have been used such as making a platter out of slate, massive stands and just massive turntables. Here is one of my favorites:

If anyone has a spare one of these please send it to me

Lastly, that platter has to turn and has to be supported somehow. The solution to this is for the platter to sit on a bearing. Now, this is an area I know next to nothing about. Most TTs have some sort of metal bearing such as this:

This is the bearing in it's housing on the TT.

The bearing pulled apart.

And, nicely cleaned up ready for clean lubrication. These are actually pics from a thread on the Vinyl Engine and the TT is the same model as mine (not bad for 35 years old hey!). These pics gave me the guts to service my bearing, and a very successful job it was.

Some TTs use more exotic bearing such as a magnetic bearing and variations on the above. The important thing is that the bearing be silent and move without drag. As such one of the big differences between a cheap turntable and a megabuck TT is the bearing as it is expensive to make a bearing which can meet the criteria for silence and free movement.

The main and really only job of the bearing is to support the platter while it is turning. This is not as easy as it sounds as some TT platters can be very heavy to aid isolation and reduce interference.

I'll leave it there. As you can see the actual turntable is a very simple thing, unfortunately it may be a simple concept but it can be very complicated to get it right.

I hope this helps some of you out there. See, it's not really all that complicated!

DS

Very well explained David . It brought back memories of many years ago . Thanks for a well done article . AlanM

[2sheds]

OK folks, no-one else seems to be motivated to start this so I figure I will.

DS

Ouch ! Looks like I've been gazumped

Anyway, good work DS

No need for 2 and I think it reads better from one author....anyone need a half finished Dummies Guide to Vinyl...?

cheers

2sheds

[Todd]

Thanks David!

As a newbie with no vinyl experience but an interest, this is a fab read.

cheers, Todd

[davidsss]

I hate to disappoint you 2sheds but I wrote this off the top of my head (I used to write for a living). Thanks for all the compliments, I'll think about what we could cover next.

Now, where are all those vinyl heavyweights to correct my mistakes?

DS

[mondie]

As others have already said, great post david, well written and excellent use of images. l am most intrigued by the paper TT, where did you see that?

Cheers Mondie

[Asteroid]

Woah excellent start, great work!

I too am intrigued by the paper tt.

[davidsss]

I saw it ages ago on YouTube and found a pic for this thread. What it shows is just how simple a turntable can be. The Voyager space craft has a record on it of human music, words, greetings etc. You just wouldn't put a CD in there are you would have to explain the red book standard. A record, though, contains the information etched into the vinyl (or gold in the case of the record on Voyager) and instructions on how to make a machine to play it on. It's simple technology, so it's simple to replicate.

DS

[2sheds]

I hate to disappoint you 2sheds but I wrote this off the top of my head (I used to write for a living). Thanks for all the compliments, I'll think about what we could cover next.

Now, where are all those vinyl heavyweights to correct my mistakes?

DS

DS,

Not just disappointed, annoyed that I seemingly wasted a week of my holidays writing an article I had mentioned I would write on these forums just over a week ago. Perhaps it is for the best, as I am not a professional writer...

2sheds

[andyr]

I know, I have an idea, why don't we put the TT on springs, better yet, why don't we just put the platter and tonearm on springs and leave the rest inside the plinth? Hey, there's an idea - an idea which you can see in many TTs, notably the Linns and Thorens TTs. These are called suspended turntables, you can see the suspension here:

This is from a Linn.

DS

Hi David,

Yes, that is from an LP12 ... but it's not the standard Linn subchassis. Is it the Funk "Charm" subchassis (seeing as it's a CF/balsa/CF sandwich)?

Regards,

Andy

[ENIGMA]

Well done, this is excellent.

It is amazing how simple the concept is, but yet so difficult to execute properly.

[wolster]

DS,

Not just disappointed, annoyed that I seemingly wasted a week of my holidays writing an article I had mentioned I would write on these forums just over a week ago. Perhaps it is for the best, as I am not a professional writer...

2sheds

Do you still have this article, 2sheds. I would really appreciate a copy.

Cheers

wolster

[RockandorRoll]

Very helpful, thanks

did someone ever write the others in the series?

i wouldnt mind learning some of this stuff

[Mick35]

David this is a 'BRILLIANT' write up and explanation. Now I know in this day and age we are all 'Time Poor', but I'm sure like all the other fellow members here that we would like to encourage you, if you get the time of course, to continue this very interesting thread.

Looking forward to your next installment

[Guest JohnA]

good work David

great write up and was a pleasure reading it