The Secret Society of Lathe Trolls

the graphs from post #13 have helped me to get on solid ground what the functionality of an elliptical equaliser, that follows my approach, should be. starting out with the graph of the depth of the groove on the record vs frequency; the iRIAA applied to the cutter head: RIAA & cutter.png in thi...

it is déjà vu all over again . I am going to repeat the 8 graphs of my previous post, but this time the right channel gets attenuated in 1dB steps, down to -20dB. first setup: fully-mono towards only-one-channel the right channel is always in phase with the left one. left channel output: L+ mono–one...

let’s have a detailed look at that fully-mono to only-one-channel to fully-out-of-phase transition. for clarity’s sake that will be done in two separate transitions: fully-mono to only-one-channel and only-one-channel to fully-out-of-phase. I took dmills’ SPICE model and set the EE frequency to 300H...

btw, you asked if I was sure about -1dB one octave out. here is a plot of a first order high pass: roll-off.png horizontal: octaves, vertical: decibels. pretty much spot on— +1 octave, -1dB +1.5 octaves, -0.5dB +2 octaves, -0.25dB +2.5 octaves, 0.125dB not that I am disputing that you can hear the n...

my messed-up posts from yesterday (damn ‘Submit’ button) and you replies from today made me realise there is more to it. so I made some graphs. I made an RIAA curve, that you apply during cutting: RIAA.png in this and all the following graphs, the horizontal axis is frequency in octaves (zero is 50H...

OK, the post above looks confusing, because I was not even half done, and the graph belongs to the text that follows below — second what does the EE do for the vertical cutting amplitude ? that is what is in the graph above. the horizontal axis is frequency in octaves, zero is 50Hz. vertical is deci...

you know what, let’s have look at what a traditional elliptical equaliser— first order filter, 75, 150, 300Hz—does. first , what does it do to the music ? well, turns low frequencies to mono. how much is it actually reducing the S component? at 20Hz, the 300Hz EE has taken off 23.5dB (17.5dB for 150...

before I jump in: thanks for the thoughts! I will not in this post go into my design too much, but more give my thoughts on the other things brought up. Add to that a high enough order that the effect is mostly gone by the time we get up where stereo direction cues start to matter. This IMHO was alw...

OK, so an elliptical equaliser is something one only wants to use when necessary. but if it is necessary, let’s have a look at how to do the least amount of damage to the music. just to be clear: all the things I describe below are only applied to the S/vertical component, unless noted. here is my l...

thanks mills and dubcutter89 for giving me a picture of the low end limitations. I have got a new appreciation for how all kind of factors determine the low-end spectrum that is actually cut on the record. also a new appreciation for the decisions, both practical and musical, that the cutting engine...

the new replies are really helping to get a grip on the whole issue, but there is one piece of information that is missing: there must be an overall hpf on the stereo signal . I certainly cannot fathom that the cutter electronics are DC-coupled from the input to the cutter head. so there must be a d...

thanks for the replies; we are getting closer to (me understanding) the heart of the matter. it will alter the stereo image (because that's what it should do!) and only rarely improves on the source... almost like: if you need it you'll hear it, and if you don't hear it you prbably don't need it (or...

thanks to Phinster and dmills for jumping in. I have got an understanding of the technical side of the EE—keeping the context of the RIAA curve and the transducer nature of cutter heads in mind—and found another approach of doing EE with much more control. but that is actually quite meaningless with...

hey everybody, I am peter sikking and I design and build studio gear at 51dB audio. I was researching (the modern use of) the elliptical equaliser over on GS —in order to design new one from the ground up—and I got told two things: very few vinyl cutters over there, try at Lathe Trolls; an elliptica...