The Thing about Analog is the Analog Thing

[MiTT]

Mitt

I want to build my own TT. I've been thinking of some designs...

Does anyone have any ideas? material, bearing....

I was thinking of doing it out of aluminum. Thoughts?

BTW-I went with Solidworks. Works well but very different then what I'm used to. Now that my sub is done, this could be the next thing..

I think the SolidWorks route was a wise choice , especially if you're going to be sharing files with potential suppliers/vendors etc. It won't take you any time at all to come up to speed on it. If you learn one parametric tool it's kind of like riding a bike - provided you understand things like parent-child relationships, constraints and degrees of freedom.

Regarding the table design, that would be a FUN project I'd bet. Here are some of the things I'd consider in my scope if I were in your shoes:

Platter Material and Resonance:
Rega uses glass or ceramic. VPI uses aluminum, aluminum and acrylic or just acrylic. Basis and Clearaudio use primarily acrylic. Lots of folks use heavy metals like stainless or brass. I think it depends on your design goals. Do you want the material to have the same resonant frequency as the disc itself? Use acrylic. Do you want to just overcome any resonance issues by mass loading the whole enchilada? Make it a massive thing out of a very inert material and clamp the disc down with a heavy weight (or a vacuum or a perifiery ring, etc.). Bear in mind that different materials store and release energy in entirely different ways. Aluminum could be problematic depending on how you use it. In tubular and thin plate forms it tends to "ring", so you would probably want to go with thicker plate stock or consider a constrained layer approach.

Bearings
That might be the biggest factor of all. You want to be sure that a) the platter spins as smoothly as possible, b) the bearing is sufficient to withstand the load demands of your drive system, c) the bearing is sufficient to support the load of your platter, d) you have to decide on a bearing type - radial or thrust? Will it be parallel or perpendicular to the shaft? Ball or roller? What will the bearing material be? How will the bearing be lubricated? How about magnetic bearings al la Spiral Groove? If I were designing a turntable from the ground up, I'd likely design around my bearing and the drive system first.

Drive System
Pretty much everybody these days uses belts. If you go that route will you mount the drive motor on the table plinth or ourboard? Outboard gives you greater flexibility and is easier to isolate from the rest of the table. Motors are sources of vibration. Are you going to add a flywheel? Flywheels add mass inertia. The downside is that outboard motors and flywheels add complexity at setup. Complexity can lead to setup errors and that leads to poor sound and bad customer relations. Should you go direct drive? That was the hallmark of the 70's & 80's. The drawback is that you either don't have a method for controlling platter rotation speed at fine levels or you have to include complicated servo circuits that are constantly measuring the speed and feeding back commands to adjust accordingly. The difficulty is that as you are correcting for one bit of speed variation you are introducing another that then also needs correcting and so on and so on. It can of course be done, but to really do it "right", that takes some committment. Technics and Denon I think are still making DD tables, but the only others I'm aware of are the likes of Rockport and Continuum - and you know how much those solutions cost. If you really want to get radical you could use a magnetic system like EAR!

Chassis and Plinth
I guess the first question is should you have one. Kuzma, some of the Projects and Clearaudio's, Wilson Benesch and Mitchell all have models that eschew a conventional "chassis" all together. Chassis are another source of potential resonance. If you do have a chassis should you isolate that chassis by suspending it like Linn does with springs, or should you do it with air chambers like VPI does with the HRX and TNT, or mass load it like they do with the Aries and Scouts. Walker really goes the mass loading route by making his chassis out of a proprietary material that brings the weight of the chassis up to about 400 lbs. (the platter weighs another 80 lbs. or so).

Tonearms are a whole different series of problems to solve, but I'm assuming you would use an off the shelf tonearm (unless you're either a mascochist or genius). Don't tell me you're thinking about doing a tonearm too?!? Either way you'll need to provide for tonearm mounting/isolation/setup/wiring etc.

Lots of very cool stuff to consider. If I had the time I would LOVE to be involved in a project like that - but I can't even get my damn CLS stands built right now.

Good luck with it and please keep us in the loop as you move forward.

 

[User211]

First off, just what is going on here? Has everyone been taking clever pills or something? Is the average IQ of analogue users just way above the norm? Has the quality of Tim’s original post excited the neurological paths of otherwise normally fairly subdued posters?

The sort of anarchistic posts Dreamer is coming out with remind me much of the sort of attitude that many students had in the day I was one, which was a good while ago. Nowadays I simply watch the government with pure hate and revulsion. Dammit, I still haven’t changed!!! Since all our e-mails are being comprehensively logged and spied on, I figure if you are going to say anything, you might as well post it on a forum because the levels of privacy are about the same

Contrary to the differing point of view Justin and I have regarding vinyl "noise", I really enjoy it when I can put on an LP for someone who isn't used to vinyl and un-muting my phono stage. It blows folks away when the music starts from as quiet a background as my Escoteric universal player. People seem to expect that vinyl will be noisy, with lots of surface noise and clicks and pops. While all of that CAN be present on some LP's, it certainly isn't the norm on my setup with my albums.

Hm, maybe Aesthetix have implemented some sort of sly noise filter... but in all seriousness, a nice new pressing can be pretty noise free. But a knackered, poorly kept, scratched, dirty disk of some quiet classical music is an absolute nightmare. I am not trying to let the side down here, far from it; I am just dealing with the truth. Sometimes the truth hurts, but it is the truth! And I wouldn’t want people to be misled into believing that if they spent X million £££$$$ on a super cool analogue set up, their 30 year old record collection that has been sitting in the cellar for years is somehow going to turn into something magically quiet , when they never looked after the damn things in the first place.

Don’t get me wrong, as you should know I do love the sound of vinyl/analogue. It’s just it has problems. Really bad ones sometimes: broken cantilevers, worn out cartridges, loss of cantilever tip/diamond, high running costs, bad setup without the user being clued enough to realise it is etc etc.

I love Nine Inch Nails, but I always know I'm listening to heavily modified electronic music recorded in a studio and manipulated in a mixing board and computer. I don't expect to know how Trent is moving across the stage, I know there isn't one and I don't care.

Trent is close to God when it comes to digital recording/sound effects. The one above watches his every move, not purely for his apparent satanic leanings (it’s all a show), but to make sure that what he knocks out is pretty stunning. Clearly, the analogue rule book has to be thrown out here; this is 100% digital ville. Sometimes I prefer Trent’s material via vinyl, but for the most part, his recent catalogue since The Fragile onwards has sounded very compelling via the CD player. The SACD release of The Downward Spiral makes the heavier tracks on that album far more decipherable and therefore easier to listen too. And the fact that he gave The Slip away free shows some signs that he is not entirely in it for the money – or at least he wishes to give that impression. I’m sure he’s not short of a bob or two, as we say over here.

For a solid Reznor treat, be sure to check out disk 2 of And All That Could Have Been. A superb mixture of tension and beauty. Listen to it and you’ll know what I mean.

So where is this going? Slagging vinyl then really sounding quite pro-digital? Well, scratch a CD and it is &^$£ forever. No romantic clips/pops, just a piece of useless plastic. Archive all your CDs and downloads to a hard drive? Are you really going to do regular backups? The disk breaks and you have lost the lot/will have to start again unless you want to pay for some data retrieval service. No denying the convenience factor, though. The problems go on and on – sh*tty s/w managing your libraries (iTunes – I absolutely CANNOT STAND that piece of software – I literally cringe every time I fire it up), low bit rates, half missing downloads from P2P services, dodgy wireless Squeezebox’s that really don’t work that well (runs for cover), silly download times for high-def content etc etc.

Why oh why do we put up with all this rubbish? And put up with it we do...
The thing is we know why – we just wanna hear some decent music played back well, cos it floats our boat.

So, principally, what do we have? Two radically different playback formats and they are both sh*te. Apart from records, that is!

Hm... a bit pessimistic when I wrote this yesterday, I feel This post was lost, but I wrote it in Word for security & peace of mind it wouldn't be lost looking at the way the site was working! Was this the result of a dodgy Sun MySQL open source database upgrade, I wonder? Or a dodgy disk? Or just Hostgator doing something silly? Guess we'll never know.

 

[User211]

I want to build my own TT. I've been thinking of some designs...

All Tim's advice above is spot on excellent. Here's a few more points.

A common trick over here is to buy and old Garrard deck and mount it in a heavyweight plinth made of say, slate. Unfortunately, this has pushed the price of Garrard idler drive TTs up a lot. In fact checking ebay USA right now, the same has happened. So I suggest looking at other 2nd hand TTs that don't have such stigma attached to them, but were well engineered.

Another thing to do is look for shortcuts - can you find a cheap 2nd hand TT with a good bearing and drive system? Can you replace the platter with you're own design easily enough?

Seems like Clearaudio have a pretty nice magnetic bearing too. They sell it as an upgrade, so can you manage to get hold of one?

 

[User211]

On platter material - if you can cop hold of a piece of Lexan - about one inch thick, and drive it with high torque (I am thinking Voyd here) by using 3 motors, that sounds pretty bonkers. I'd try and keep the motors away from the main chassis to prevent noise/vibration problems for such a design, though.

Lexan is bullet proof and is supposed to dissipate energy really well. The Voyd sound was incredibly alive and in your face... so if that is what you are looking for, it might be an option.

Might be an idea to keep in mind adaptability. What I mean is you might not like the sound of the finished result. So being able to swap platter material, for instance, will really help in fine tuning the deck.

It is probably OK to use aluminium as long as you damp it using something like Densodamp. I have it under my GyroOrbe sub-chassis and a makes a very noticeable difference.

Hm... could go on a lot here. I always liked the idea of building my own TT too... Have never gotten round to it, though.

 

[Bernard]

On platter material - if you can cop hold of a piece of Lexan - about one inch thick, and drive it with high torque (I am thinking Voyd here) by using 3 motors, that sounds pretty bonkers. I'd try and keep the motors away from the main chassis to prevent noise/vibration problems for such a design, though.

Why would you want high torque? High torque is important just for startup, but what is more important is speed stability. There is one TT manufacturer (can't remember which one) that makes a 'table that you have to start up by hand; he claims that high torque motors and speed stability are mutually exclusive.

I would have no problem with a TT that came up to speed slowly so long as it stayed at that speed.

 

[RichTeer]

Why would you want high torque? High torque is important just for startup, but what is more important is speed stability. There is one TT manufacturer (can't remember which one) that makes a 'table that you have to start up by hand; he claims that high torque motors and speed stability are mutually exclusive.

I think you're thinking of Nottingham Analogue (of the Spacedeck fame).

 

[Dreamer]

There is one TT manufacturer (can't remember which one) that makes a 'table that you have to start up by hand; he claims that high torque motors and speed stability are mutually exclusive.

I imagine the manufacturers of Heidelberg printing presses, and the folks who make the turbine systems in nuclear submarines would have a thing or two to say to such a statement...

 

[tonepub]

What do Heidelberg printing presses have to do with turntables?

 

[User211]

Why would you want high torque? High torque is important just for startup, but what is more important is speed stability. There is one TT manufacturer (can't remember which one) that makes a 'table that you have to start up by hand; he claims that high torque motors and speed stability are mutually exclusive.

I would have no problem with a TT that came up to speed slowly so long as it stayed at that speed.

Isn't that because it has an insanely high platter mass? High mass = high inertia = speed stability.

The Voyd argument was the platter was quite light. Therefore, stylus drag during high groove modulation could cause speed instability. Solution? High torque drive to stop it.

Quite how true this is I don't know i.e. is stylus drag really that substantial?

Getting three motors to work in exact sync is probably not 100% achievable though.

Oh - maybe I don't look at the government with complete pure hate & revulsion all of the time - more sorrow, and "that isn't the right thing to do" a lot of the time.

 

[wrat]

What do Heidelberg printing presses have to do with turntables?

They print covers for albums?

 

[slowGEEZR]

I imagine the manufacturers of Heidelberg printing presses, and the folks who make the turbine systems in nuclear submarines would have a thing or two to say to such a statement...

Ha ha, good one Richard, apples to oranges though. The idea with the low torque motors in turntable usage is a little different. The idea is that if a heavy platter is properly spinning on a well designed bearing then all you need is a very little effort to keep it turning and that motors with high torque might actually introduce more fluctuation. Of course, if the bearings were not very well designed and there was more resistance, then a higher torque motor would be beneficial.