Patterns and low frequency

[sunkingrecords]

Hello all:

I'm having this problem, embossing on CD, if you can see in the picture:

IMG_4661.JPG

IMG_4662.JPG

On the outer edge of the CD, now I'm getting this low freq which appears out of nowhere (is not in the audio signal). It seems to be related to te weight of cutting, if I use less weight tends to dissapear but the grooves are too shallow to track properly if I do that.
I'm using a backwards saphire with an inclination.

The rest of the disc sounds "fine" for my own lo fi standard. I cut perhaps 30 or 40 tests, before this started to happen, and I don't seem to be able to get rid of it.

Any clues?

Kind regards

Miguel

[Jccc]

Hello. from what it looks like it could be that your feedscrew is not fully mounted correctly.
i had similar groove patterns and low frequency sounds on dubplates only to realize that i did not fully mount my feedscrew on my Presto 6n.

Maybe that could be the issue. post your results and maybe someone can help you out

[sunkingrecords]

Hi Jccc!

I will check that!
On the microscope it looks like I have a vertical modulation, as the grooves get wide and thin even though the audio feed is silence.
Perhaps an up and down movement of the CD could be causing this?
I lock it in place using double sided tape, but that is around the middle of the cd, the outer edge just sits there thanks to the flatness of the medium.

Kind regards

Miguel