interesting phenomena in the cutting room


We've (my friend Bob and myself) been working on an LP cutting lathe for some years. Its been a while refurbishing the lathe itself, finding parts and solving problems/puzzles, rebuilding the electronics, etc.

The lathe itself is a Scully, the cutterhead a Westerex 3D and the electronics the 1700 series built for the cutterhead by Westerex.

About 6 weeks ago we finally hit upon the magic combination of stylus temperature, vacuum, depth of cut, etc. It works beautifully! So we have been playing with parameters, including different amplifiers. The stock amplifiers were built about 1972 and are solid state.

Now those of you that know me know that I am all about tubes. But the stock amps worked quite well! As we gained familiarity with the system, we found out why: the Westerex cutting system is a high efficiency cutterhead- it does not take a lot of power to make the head work. It can easily cut grooves that no cartridge could ever keep up with, and do so without breaking a sweat. So the amps, which can make 125 watts, are loafing through the most difficult passages.

I had a Dyna ST-70 that I had rebuilt so for fun we swapped that amplifier in and it did quite well. Our next step is to use a set of our M-60s, as the cutterhead is an easy load relative to most loudspeakers.

What is interesting about this is that we can make cuts that literally demonstrate the audible differences between amplifiers, something that can be demonstrated on any playback system.

Its also apparent that the cutting process is relatively unlimited as a media compared to any other recording system. The dynamic range is well beyond that of analog tape or any digital system- like I said, it can cut grooves with such range that no cartridge could possibly keep up, yet is dead silent (if the lacquer is OK, that is). The real limitation in LP recording is the playback apparatus, not the cutters.

There is a fun little forum website for more information called 'Secrets of the Lathe Trolls'. Here's a post on that side made by my friend Bob (Bob has run a recording studio for some 20 years and was a roommate of mine in college):

http://lathetrolls.phpbbweb.com/viewtopic.php?p=19435&mforum=lathetrolls#19435
128x128atmasphere

Showing 3 responses by bdp24

Wouldn't it be great to have the same recording available on all three formats---analog reel-to-reel, LP, and CD/SACD, produced with the care necessary to insure they sound as much alike as possible? One could then compare, for instance, the sound of a recording from it's master tape to the sound of that recording as reproduced by a given phono cartridge/phono amp/digital player under review.

There is an excellent documentary film entitled Tom Dowd & The Language of Music. Tom, recording engineer at Atlantic, Stax, and other labels, would go into the studio, walk around the room, stand in front of each instrument, then go back into the control room and attempt to replicate the live sound he had just heard via his recording equipment. He recorded a lot of the greats---Ray Charles, Aretha Franklin, Derek & The Dominoes, lots of Jazz.

Doug Sax of Sheffield Records and The Mastering Lab evaluated a piece of recording equipment by passing a mic feed through it and then into the monitor system in his control room, then by-passing the piece, listening for any change in sound, referenced to the sound of the live mic feed (from a source in the studio itself). Doug was looking for transparency.  

Right Myles, the comparison would be of not only the formats themselves, but of the playback gear as well. It was in the latter sense I was suggesting a recording be made available in the three formats. I believe it possible to produce them all in such a way as to insure equivalency amongst them. One could then compare the sound of a recording on, say, two different CD players, and the one producing sound most like that of the tape the CD was sourced from would then be judged the more accurate, at least in one way or another. Of course, if neither player is perfect, each might be better than the other in different ways.