Charts...Disc cutting timing per LPI at 3 speeds

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Re: Charts...Disc cutting timing per lines per inch at 3 spe

Unread postby Steve E. » Sat Jul 13, 2013 1:34 am

tagged: Impact Sound Recording Studio of 7102 1/2 Castor Ave in Philadelphia, Pennsylvania, 19149 USA.

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Re: Charts...Disc cutting timing per lines per inch at 3 spe

Unread postby ejemmons » Sun Jul 14, 2013 2:12 pm

Beautiful! Thank you very much, Steve! [To be framed]
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Re: Charts...Disc cutting timing per lines per inch at 3 spe

Unread postby Steve E. » Thu Jan 02, 2014 1:02 pm

I'm thinking of updating these charts again.

Questions:

1) Which of these is the most useful to YOU? (I'd leave the measurements alone on the "IMPACT" one.

2) It sounds like my "extreme" version should have a larger cutting area for 7" records

3) It seems to me that the "total rotations" columns aren't really necessary. Does ANYONE use those? I sure don't. They are interesting to look at once, but they don't help you cut.

4) I think it might be useful to include a columns featuring the RIAA standards for location of inner locked grooves. I WOULD use those.

5) It would be helpful to include data on the absolute distance between grooves at a given LPI. Maybe I'd call this "Absolute mils." or "Groove Spacing" ... looking at boogievan's thread here: viewtopic.php?f=9&t=3863&p=26013#p26013
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Re: Charts...Disc cutting timing per lines per inch at 3 spe

Unread postby Steve E. » Wed Jan 08, 2014 2:07 pm

I'm just about to post a radically revised version of the charts....new data, new columns (groove widths!), new calculations, new headings....but don't worry, I'll leave the old ones available.

One thing I'd still REALLY like feedback on is anyone's preferred "Extreme Max" cutting space for 7" records. piaptk? tragwag? The idea is that this last chart is for records that make no efforts to conform to RIAA standards or even decent fidelity.

What versions of the chart do people use? I am finding that the FIRST one, old "Conservative" Impact Sound, is actually the only one that gives me helpful data for doing 12" dub cuts at 33 1/3. Everything else is too extreme; in fact, I wonder if I shouldn't make one that is more quite a bit MORE conservative than Impact Sound, as I do get pretty low-fi on my Presto in the final couple of minutes, if I use that as a guideline.
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Re: HELP: Charts...Disc cutting timing per LPI at 3 speeds

Unread postby tragwag » Thu Jan 09, 2014 12:37 pm

I use the "more safe" one as a guide, especially trying to stay away from the very inner 1/2" before the label.
the longest I've cut at 224 LPI is about 7:15 give or take.
I also make my blanks myself, so they are slightly variable but most nearly 6 7/8".

One vague measurement on a disc I cut all the way to the center hold down, measures 1 and 3/16" from the edge.

Also I can't remember exactly how it helped, but looking at your chart with total lines, etc helped me time out an 8" cut I was making.
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Re: HELP: Charts...Disc cutting timing per LPI at 3 speeds

Unread postby Steve E. » Fri Jan 17, 2014 11:10 am

I think you must have cut 1 1/2 " to get 7:15 on a record at 224 lpi.
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Re: HELP: Charts...Disc cutting timing per LPI at 3 speeds

Unread postby ejemmons » Sat Apr 19, 2014 9:38 pm

I use the most conservative version, and tweak up from there.
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Re: HELP: Charts...Disc cutting timing per LPI at 3 speeds

Unread postby Steve E. » Mon Jul 14, 2014 1:36 pm

This was the version I was "about" to post, back in January. I was sending it around privately in the hopes of getting some feedback, but as happens, I lost the plot.

It's an intense revision, but still very much a work in progress. You will see that I've added a lot of info based on RIAA specs, plus a column devoted to "pitch", as well as the groove widths in mils you will get with different groove/land ratios.

I suspect that chart #3 is almost useless. I think it might also make sense to have an even more conservative version of this, designed for "hi fi" cuts. Even charts 1 and 2 push the numbers, and you're better off lopping off a couple minutes of running time per LPI to get best-sounding results. Any data that people can supply will help.

See those three purple/pink boxes in the "ratios" section of the chart? Those are based on rough rule-of-thumb suggestions from Len Horowitz. The idea being that as you are packing grooves tighter, the groove/land ratio might change so you can get a deeper cut. You will have to modify your audio levels, or roll off the bass, to accommodate the tighter ratio.

I have not double-checked this as of late, but I am going to guess that on the "extreme" chart, the cutting area might run over the listed label area, esp for 7" records. Caveat emptor.
Attachments
disc cutting timing chart_2014_jan v3b.pdf
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Re: HELP: Charts...Disc cutting timing per LPI at 3 speeds

Unread postby Steve E. » Tue Jul 15, 2014 12:22 pm

Same exact content as the pdf. The pdf may print better, and it is a smaller file. Clicking on these thumbnails should allow them to fill your screen. Clicking again will allow zooming in. (Works on Firefox, at least.)

disc-cutting-timing-chart_2014_jan-v3b-1.jpg

disc-cutting-timing-chart_2014_jan-v3b-2.jpg

disc-cutting-timing-chart_2014_jan-v3b-3.jpg

disc-cutting-timing-chart_2014_jan-v3b-4.jpg
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Re: Charts...Disc cutting timing per LPI at 3 speeds

Unread postby sakuszi » Thu Mar 24, 2016 9:42 am

Sheriff thanks! This is very helpful information!
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