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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
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Showing 11 responses by atmasphere

atmasphere's avatar
atmasphere OP
11,615 posts
 
Hi Peter, what we have found about that pesky RTA is its not really a standard. The problem is variance in the cutting stylus. Under the scope they all look a little different, and to get them to behave you have to adjust the head up and down a little. But for the most part the stylus temperature seems to play a bigger role. We did shoot for about 2 degrees negative but you can't count on that to work with every single lacquer. Plus the stylus is only good for about 10 hours and during that time you have to compensate for its wear. So RTA is more of a thing to try for as long as everything *else* is working :)

Mofi, the intent is for sure to release projects. I expect that most of them will be local initially, in fact we already have several lined up. But the plan has been all along to have the first transformerless vacuum tube LP mastering setup. Its nice to say we are finally there...

To that end we modified a set of M-60s to operate entirely without feedback. The system itself provides 30 db, which is needed to kill resonance in the head, and without it you can't get channel separation! This has to do with how the mechanism is suspended. Anyway, the stock amps employ feedback but in any servo design, nested feedback loops are usually a recipe for stability issues. But so far we've not run into any of that, once we started dialing in the trackball height, stylus depth, temperature and the like, its actually been pretty well behaved.
atmasphere's avatar
atmasphere OP
11,615 posts
 
We master LPs for other labels. Most of our work has been for Nero's Neptune, which is a local label in Minnesota. We've also done a number of independent projects. Most of them have not been what I would call audiophile, for example we mastered a reissue of a Spider John Koerner LP called 'Folk Songs Like they Used to'... The label was happy because we got it sounding better than the original. Fortunately in that case we had the master tapes which were in excellent condition.

That does not always happen. We did a project for a punk band that was recorded in mono on an old Ampex 300 tape machine, which should have turned out spectacular, but I don't think the mics used in the recording were all that good. We also figured out that the tape machine must of had a microphonic tube as we could see an intermittent signal in the grooves that was at about 16KHz.

So we've been pretty happy about the results- but so much depends on the master tape or master file!
atmasphere's avatar
atmasphere OP
11,615 posts
 
Do you have one you want mastered to LP?

For some reason I can't do a PM to you via your moniker.
atmasphere's avatar
atmasphere OP
11,615 posts
 
With out importance level in that process and with out know almost nothing about I list some limitations on that normal process ( not " audiophile " but normal. ):

- quality level of microphone.
- microphones place during recording.
- use of limiters, equalizers, reververation or other electronics artefacts.
- quality level of monitoring system.
- bias of the recording engineers or recording producer to some kind of sounds.
- edition work.
-dubbing.
-mastering and platting.
-quality level of all the electronics surrounded the recordings: microphone amps, cables, connectors, amps and preamps, overall recording consoles, etc, etc.
-quality of pressing.
-and many other " characteristics " where you can put some light to ignorants as me trying to learn.
Of the things listed most have nothing to do with the LP except the mastering, plating and the resulting quality of the pressings. IME the quality of mastering means a lot more about the pressing quality than the work of the actual plant.

We did one job where the customer was doing the pressing at United, which is not known for pressing quality. I knew some people that got a project done there and the finished LP seemed kind of .... compressed. But in our case when we got the finished pressings back they sounded fine. We didn't add any compression to the recording- usually with LP there's no point to it.
atmasphere's avatar
atmasphere OP
11,615 posts
 
Hello Raul, I didn't know there were new posts to this thread. I'm still trying to sort out this new format Audiogon is using and one of the things that is frustrating is it does not use a good 'new post' system!

Regarding your comments, they were in fact addressed quite well in halcro's response just above. Most of what you commented about is a commonality with all good recordings- you want the recording to be as good as possible regardless of the format.

We've resorted to building our own equipment for the recording process as well. Its not to accommodate anything to do with the LP so much as it is to know that we are giving the signal from the mics the best chance that we can give it!

Overall otherwise I've found the LP format to be pretty accommodating
It has wider dynamic range than tape, and effectively has wider range than CD as well, despite the CD having greater dynamic range on paper. As is often seen in this sport, what is practical and what is on paper are often two very different things!

Y'all have a Happy New Year!
atmasphere's avatar
atmasphere OP
11,615 posts
 
Hello Raul, The acronym 'TEA' returns 67 different hits on Google, none of which make any sense in your post.

But I can say with a great degree of confidence that you are talking about recording challenges and not anything that is specific to the LP.

FWIW we have been experimenting with the direct-to-disc process. We have also been using our OTL amps in the mastering process (still refining that).




atmasphere's avatar
atmasphere OP
11,615 posts
 
The quality of the recording has more to do with the producer than anything else. We've done some projects where the recording was clearly not up to snuff but that is what the band or label wanted, and its client/vendor relationship. We've tried to to the best job we can, and so far not had to use any processing on any of the projects we've seen (which has meant that in some cases it took several tries).

Most labels don't want to spend the extra time it takes with a project to do that so the result if often some sort of limitation in the recording.

FWIW, we've done some projects through QRP (Acoustic Sounds' pressing plant) and the results have been spectacular. The groove noise is nearly non-existent compared to other pressing plants- the sound literally erupts from silence, much like playing a lacquer for the first time. But my experience in general sounds like it is very different from yours- I've yet to buy a defective LP from Acoustic Sounds- is it possible you have simply had a run of bad luck??


atmasphere's avatar
atmasphere OP
11,615 posts
 
How difficult in terms of budget, contract etc to re-issue let's say Hank Mobley "Soul Station" or Oliver Nelson "Nocturne" from original tapes? Did you try any of a kind?
To do this you have to gain permission to do the project (usually with some sort of financial consideration); once done then its fairly nuts and bolts.

We did a release of a Michael Rother project about 18 years ago that went fairly well. On small projects the mastering is the major cost and the pressings a smaller but significant percentage. So there's no good answer until you know how many LPs are to be made; experience says that you should have a really good means of selling them set up before you embark on the process!
atmasphere's avatar
atmasphere OP
11,615 posts
 
What's a True Expert Audiophile??

Regarding 'accuracy': a big problem in knowing accuracy is your reference. I use an LP that I recorded myself, and having the master tapes know how its supposed to sound. So the LP is very useful in that regard- in playing it I can instantly tell how well a system is playing in a number of regards. I am however convinced that one needs such an LP in order to understand what accuracy is all about. So you must have some similar reference that you made. Is it available?
atmasphere's avatar
atmasphere OP
11,615 posts
 
Raul, IMO/IME as soon as someone tries to set themselves up as an expert in this field, they run the risk of Audiophile Guru Syndrome (AGS), wherein if the knowledge does not emit from their mouths then it must be some form of blasphemy. I think we have all seen this at one point or another. IMO true mastery is the understanding of how little one actually knows.


atmasphere's avatar
atmasphere OP
11,615 posts
 
To really get that right though the LP should be recorded Direct to Disc so that the limitations of the other formats aren't built into the recording.

We did our Canto General recording on both LP and CD, both made from the master tapes. Which means that at best, they sound pretty close to the master tapes, which sound great. But take away the tape hiss and bandwidth limitations and it could have been better. But the magic of tape is that you can re-record if you don't like it the first time through...
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