Attempting to cut the World's Largest Record

[cogzoid]

First, a little background. I am an engineer/artist in Los Angeles. Our company gets hired to build bizarre things for events, commercials, music videos, etc. It's not our only line of work, but it's usually the most challenging/fun. We've been hired to build the world's largest record and record player, for a charity (http://www.musack.org). The record will be decorated by an artist and they're hoping the press will draw attention to the charity.

Currently Guinness doesn't have a record for the World's Largest Playable Record, so the bar is low. Considering the budget constraints, we're going to shoot for a 4' record. It doesn't need to play back super hi-fi. But, the music should be decent enough to be convincing.

I'm in the process of designing a 4' diameter turntable. The RPM will be controllable, and the inertia should make for a nice platter.
I'm planning on bolting on a mount for a screw to drive a cutting head across the record. This is pretty standard stuff, so I don't foresee a big problem here. (let me know if there are devils in the details I should look out for!)
The cutting head is more of the magic. I need help in building a DIY head. Buying a used one is cost prohibitive, if not extremely difficult. It looks like you guys have some diy versions in the forum. It'll take me some time to read up on all of them. If there are designs that worked well, I'd greatly appreciate some direction... Remember, I'm only looking for decent, not necessarily the best. Time/money are a factor in this project.

If by chance anyone lives in LA and wants to be a part of the project, we do have a small budget that we can compensate for your work!

I'll keep you guys posted with the progress as I figure things out.

Thanks in advance for any advice.

[opcode66]

I live in LA now. I do professional vinyl mastering. I also invent, innovote, modify, computer control, repair gear, etc. Check out my youtube channel for all sorts of videos of my work.

http://www.youtube.com/opcode66

[cogzoid]

Awesome stuff! Let me PM you my deets. Let's talk!

[ROLANDJAYS]

That sounds pretty cool.
Can't wait for the results

[diamone]

Trying to cut a four foot record with a normal size groove and cutterhead is going to be severely problematic.

Although mastered on wax - look at the problems they had cutting the 50CM center start 120RPM Pathe's around the turn of the 20th Century. The groove had to be so wide (6-8 mils) as well as so shallow (30-40 μM) just for it to track properly without a lead screw as on a cylinder player.

To get something stable enough to engrave, and stiff enough not to bend when loading and unloading the disc, the aluminum substrate is going to have to be in the neighborhood of a quarter-inch thick.

The lacquer coating similarly needs to be four or five times as thick as that on a conventional lacquer.

The groove is going to have to be 8-12 mils wide and 150-300 μM deep just to track.
Most of the 2 minute super-hot 45's from the 60's were 100-120 μM vs 70-90 on a normal cut.

Have to get somebody at a precision aluminum company to make you the substrates and somebody at Apollo/Transco to coat the blanks for you.

Same thing with the platter and vacuum system have to be equally oversized as does the gearbox.

Look at the 1966 American Printing House for the Blind research leading into the proposed production of 4 RPM discs - half of the eventual 8 RPM talking book speed and read up on the problems they had.

Divide out the varying linear speed on a four foot disc recording at 4 RPM starting inside at maybe the one-foot mark and you will find it to be sufficient for your needs. Any faster and you risk destroying your cutting stylus unless both your substrate and your lacquer coating can be made to medical-grade smoothness - and even then it's still risky.

This is one reason you will never in your life find a sixteen inch electrical transcription recorded at 78 RPM.

Good luck.

P.S. You're in L.A. - Stop by Len Horowitz's mastering studio in Culver City on Washington Blvd and pick his brain if he has time.

[Bahndahn]

To cut the worlds largest record does not necessarily require the worlds largest cutterhead, stylus, so on, and so forth. It would still be the worlds largest record without every detail to scale. However, if everything was in fact scaled up x:x, it should be able to dig on into some polycarbonate and behave rather similarly. It seems like working with lacquer would be a little cumbersome.

If you build the largest cutterhead, groove format, and cut grooves with it, you will need to also build the worlds largest playback stylus/transducer to provide 'proof'. You could startle two birds with one stone that way.

You could cut standard grooves of some sort [and it would still be the worlds largest record] and play it back with less trouble, yet trouble is not necessarily something this project is worried about!

This is weirdo-cool stuff folks; please keep sharing your progress here.

[diamone]

Too bad those gigantic advertising models of phono styli and cartridges that graced the walls and counters of stereo stores in the 70's are only made out of plexiglas. I think I still have the one for nude square shank hyper elliptic stylus not in a cantilever. It's like a foot tall and maybe 3x3 inches square.

[opcode66]

- Polycarb disc cnc cut from a 4x8 sheet.

- I can scale and print my cutterhead to whatever size ends up working best.

- I can even make a custom cartridge to any size required. with coils wound by yours truly with flat wire

- I can have a custom cutting stylus made to any size required by my styli folks.

- I can also have any custom sized playback styli created by them.

For every problem there is a creative solution and a crafty innovator!

[EpicenterBryan]

And once the project is successful ...

Record head board.jpg

[tape]

skip all the problems involved in cutting and either lasercut/ or CNC a hill and dale record (made of plastic)
This will be low fidelty and mono, but, I think fine for this project.
Then the challange is to make a playback device, a standard pickup could be used, and some motor as turntable.
You would 'just' need a very long tone arm.

I am not sure why people are suggesting supersize laquers etc - when you only need one record.
Let us know how it progresses!

[opcode66]

I think this will be standard groove. Why must it be mono? I disagree there. Would appreciate understanding your reasoning.

My 3d printed stereo cutterhead scalled up in size will work fine in my opinion. We will find out...

A custom playback decice is in the works. The tonearem will be two staged with a pivot point. The first stage is fixed. The second swivels.

The project is being completed for a worthy charity. I'm donating my time.

Low-fi with background noise is totally acceptable. It just has to play once.

[tape]

was just some thoughts regarding this
I imagined a hill and dale record (mono) as most suitable.
But if you have a recording head done that's awesome!

Going to be exciting to see what come out of this!

I have seen picures of, I belive 24 inch records, used on broadcasting, never seen anything bigger

- btw: the worlds largest record is already in LA, on top of the stadium
But not playable ofcourse, it's a dummy

[opcode66]

The thread title should really be world's largest playable record.

My cutterhead project thread.
http://lathetrolls.com/viewtopic.php?f=15&t=5250&start=160