Cyclic noise when cutting laquers

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eav987
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Joined: Wed Nov 24, 2010 9:33 am

Cyclic noise when cutting laquers

Post: # 24786Unread post eav987
Tue Apr 16, 2013 8:14 am

Good day!

We need the advise.

We have the cyclic noise when we cut the lacquers without any signal injection.
And if our SAL74B and SP172 is switch off, we have the noise too.

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opcode66
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Re: Cyclic noise when cutting laquers

Post: # 24788Unread post opcode66
Tue Apr 16, 2013 10:06 am

FYI, you will hear a lot of noise in an unmodulated groove if you cut with your amp off. You will also get noise if the amp is on but the Oper buttons are not illuminated. It is a constant scraping noise. From what I gather it is because when the amp is on the stylus is held rigidly steady. When the amp is of the stylus has some play. And, when actually applied to discs with the amp off it wiggles about while cutting and produces the noise.

But, it sounds to me like you are having a repeated noise once per revolution. That sounds more like something is not balanced/leveled/alligned. I would go over you platter alignment. Be sure it is flat in two dimensions. Make sure your suspension is flat. Make sure the suspension rides the line straight through to the center spindle.

Finally, check you dash pot. There is an adjustable nut in the dash pot that governs the flow of oil. Too tight and not much flow. Too loose and too much flow. You have to get it just right and that setting is unique for each lathe. If you don't adjust this correctly you will hear a swooshing noise in your cuts once per revolution.

If you are hearing a high pitched whining sort of noise and it is constant through the cut then your culprit is the small vacuum tube on the bottom of the cutterhead. It is either too close to the stylus or it is not at the right angle. It needs to be slightly back of the stylus. And, the oval opening must be clear of the torque tube that holds the stylus. If the oval opening is in any way overlapping the torque tube you will get a whistle from the air rushing over the tube and into the oval opening. This whistling causes the stylus to vibrate and is captured in the unmodulated groove being cut.

A final source of noise could be your audio source. In the case of computer users, the computer power supply or the monitor might not be shielded very well. I had line noise and ground loop hums that I had to deal with coming from my computer. I added a HumX to my monitor power cord which solved the issue for me. It was a very high pitched noise. It would happen more intensely whenever I moved the mouse around or whenever anything repainted heavily on screen.
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concretecowboy71
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Re: Cyclic noise when cutting laquers

Post: # 24795Unread post concretecowboy71
Tue Apr 16, 2013 11:11 am

I agree with all of Opcode's suggestions. I have been down each of those roads before.

Good luck and eliminate one potential problem at a time so you know exactly what you changed when the sound finally goes away!
Cutting Masters in Bristol,Virginia, USA
Well Made Music / Gotta Groove Records

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