HARA 805/ATOM diamond cutting setup. Distortion and shallow groove depth.

[Liam walker 82]

Hi everyone,
I am setting up my HARA 805 to cut with a head from an ATOM.
I have had various results and to be honest I’ve been shooting in the dark to get a decent result.
The main problem I’m having is distortion on playback.
I have adjusted the input signal level, the input gain on the lathe, the groove depth, stylus position and disc temp.
This either changes nothing or makes it worse.
The main problem I’m having is I am told the internal amp in the HARA is a class B 10w 8ohm amp and the cutterhead is from an ATOM which is 2ohm. I was also told by the seller that if I keep the input below -6db on the HARA VU meter then the head will work fine.
What is confusing me it that when I watch videos of cutting with mono heads you can clearly hear the audio coming through the cutterhead as it’s cutting. On my set up you can’t hear the audio but under the scope it’s cutting wildly. Crashing grooves etc etc,
I may just be overdriving the amp and have a low stylus weight.
I have created an RIAA curve and applied a limiter/comp to the input signal which I have yet to try.
Is there a base line starting point that I’m way off??
Here are some images of my badly crashing grooves through a signal sweep at 1k 0db.
Any thought and advice would be greatly appreciated.

[12bitcuts]

Hi,

On the Atom, I have to use aggressive EQ/filter on some of the midrange bands going in to allow for a better cut (using diamond w/ heater).
I also tend to cut pretty hot, but overall getting a good sounding cut with an Atom cutterhead on an actual Atom disc cutter is a challenge in itself.

FYI: the Atom/Vanrock uses an STK011 power amplifier which according to the data sheet is rated 6.5W @ 8 ohms.

https://pdf1.alldatasheet.com/datasheet-pdf/view/169285/ETC2/STK011.html

Here are a couple pics of the main PCB for reference.





I just picked up a Dayton DATS setup and ran the Impedance Sweep on the cutter head.
No idea if I am doing this correctly so take these results with that in mind.




Bypassing the internal amplifier / audio path of the Hara might be worth experimenting with.
I am getting ready to test some external amp options with my Atom soon.
I also want to learn a bit more about the cutter head itself and if it can be improved or modified.

Ideally, a retrofit where I can use a different cutter head altogether would be ideal.
That might be an option for your Hara as well with some modification.

Check this post out:

https://www.lathetrolls.com/viewtopic.php?f=1&t=9493&p=60530&hilit=Hara+805#p60530