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Topic: Mastering Vinyl (Read 59290 times) previous topic - next topic
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Mastering Vinyl

Reply #51
The problem is with the baggage that comes with calling something a vinyl simulator. There is a market for a vinyl simulator. Just look at the prices of the old DCC CDs and consider some of the comments Steve Hoffman has made about how he went to great lengths the make the CDs and the LPs sound as much like each other as possible.

Of course the other problem is you need a mastering simulator to go with the vinyl simulator. Good luck with that.


That's it in a nutshell. From the consumer viewpoint the mastering and the baggage that the medium adds all by itself are inseparable. You hear the two inextricably mixed together.  In very many cases the mastering is the stronger effect, but there's no way to know that based on evidence that consumers receive as a retail product.

In the  days of vinyl, the whole process of making a record, often starting back when the music was arranged or even written, was designed to optimize consumer saitifact with the finished product. This was exactly as it should be.

When digital became the primary delivery format, some of the optimization for vinyl logically went away because the develpment process typically remained the same through mixdown.

When someone has a preference for music developed a certain way it would be fanciful to try to break the delivered product down into its individual production steps to try to determine which was the best or even just the strongest determiner of the outcome, because the outcome is just a personal preference.

From an audibility standpoint it doesn't matter whether you are mastering for CD, DVD-A or SACD, so-called high rez formats make no difference. The original source material isn't necesasrily audibly degraded by being 16/44.  Tracking and mxing are the only steps of the production process where hi rez formats could possibly make an audible difference.


Mastering Vinyl

Reply #53
For this title a "compressed" CD version was mastered first. Then when they came to master the vinyl they cut it compressed and uncompressed. The powers that be prefered the uncompressed LP test pressing and so it was decided that they would use the uncompressed cut. They then decided to include an uncompressed CD packaged with the LP.  The "compressed" version was not "hypercompressed." This was considered to be a good mid point between sound quality and market forces.

Mastering Vinyl

Reply #54
Read what I said - my question what about production process, not the chronology of producer's choices.

Mastering Vinyl

Reply #55
I read what you said Arny. Not sure how mastering is not part of the "production process." But anyway... The only "fork" was in the mastering. Every version, the compressed CD, the compressed LP test pressing, the uncompressed LP, the uncompressed CD and the MP3 all came from the same master tape.

Mastering Vinyl

Reply #56
Article in the NY Times about Tom Petty's "Mudcrutch", and the difference between the "normal" CD and the less compressed vinyl/CD special edition:

http://www.nytimes.com/2008/06/23/business...q=vinyl%20audio

Has anyone got any comparison samples to listen to?

If it's as reported, this is great - except that to get the decent CD, it seems you have to buy the vinyl! I suppose if the record sleeve was pretty, you could hang it on the wall.

Cheers,
David.

Mastering Vinyl

Reply #57
I think it's important to keep the timeline of predominant mastering practices clear in the wiki.

Up to about 1980, as I understand it, it was typical in LP cutting to sum the bass to mono, reduce the low bass, compress 2:1 or higher, and so forth.  Starting ca. 1970, it was typical to make a cutting master that was made from a feed split from what went to the lathe when the LP was first mastered.  Subsequent LP masterings were made straight from this cutting master without other intervention (so they were identical to originals except 1 generation down).  Many first generation cds were made from these same cutting masters.  In some cases, where the actual masters are inaccessible, these tapes are the source for all cd issues.

Around 1980, digital preview heads became prevalent.  These, plus a general proliferation of higher performance phono cartridges allowed less draconian processing of the master tape to fit on vinyl and longer, less compressed records to be cut.  But they mean that almost all vinyl since the 1980s is actually cut from a 16-bit signal.  The differences between 1980s vinyl and CD are quixotic.  Sometimes the LP is very long, say 60 minutes on a (quiet or bass-reduced) single disc.  Other times tracks were cut from the running order.  Often one mastering house did the CD and another the vinyl--and often this was not credited but discernible only from the mastering stamp on the vinyl.  Sometimes the credit on the sleeve is for the vinyl (even on the cd version), sometimes vice versa.  As one example of mastering protocol for high-profile bands, releases from Guns'n'Roses were mastered for cd in-house by Barry Diament, and for LP at Masterdisk.  But often, the same cutting house did both.  In many cases the vinyl was cut from the cd, in other cases from the master tape (or a digital copy) used to make the CD.  There is no firm rule but in general LP vs. CD masterings from this era are very similar in tonality.  [The gearslutz quotes from the Soundgarden mastering engineer reflect what I understand was typical.]

In the 1990s, major labels stopped making vinyl except for a few one-off pressings or licensing for bands that had a vinyl fanbase.  Typically the mastering house that did CD would send 16/44 files to the vinyl cutting house.  Indie labels continued to sell vinyl, and typically used the the same master (and mastering house) for CD and LP.  Again, these usually sound very very close if using top flight equipment.

Thus, the vast majority of vinyl releases made since 1980 were made from the 16/44 digital--either as source tape or as feed from the digital preview.

Things changed a bit with the vinyl revival--which occurred at roughly the same time as the loudness wars.  Sometimes, instead of using a hypercompressed file that is identical to the cd, LP mastering houses are given pre-[CD] mastered files, 16/44 or higher, and thus create a higher fidelity version, though it may also have different eq.  And audiophile reissues often eschew or minimize compression and filtering, as well as eq'ing to taste, creating an audibly different sound.  And that is where this wiki comes in, to explain that in some select cases, the vinyl master is higher fidelity.

As an aside, I believe it is the relatively gentle compression used in LP mastering that is largely responsible for the "sound" of vinyl that people like [leaving aside placebo issues].  I believe this also explains the popularity of "first pressing" and "Japanese first pressing" cds that were often mastered from pre-processed (for vinyl) "cutting masters".

Mastering Vinyl

Reply #58
Nice idea usernaim but trying to generalise like that is pretty meaningless. At any given point in time the equipment used in pressing plants was not standard. So a wide variety of equipment of varying levels of quality and sophistication were in use across the industry.  I'm talking about up to the end of the 80's when I left the industry, maybe it's more straight-forward now - and say, since the 90's - with volumes being lower and pressing plants fewer.
Also, while cutting a lacquer is a bit of a black art a cutting engineer would never "sum bass to mono", apply eq, compression or anything else without the OK from the artist or producer. The last thing you want is for your test pressings to be rejected and have to re-cut. Any "preparation for production" like that would usually have been done by the mastering engineer who produced the tape from which the lacquer was cut. That would invariably be a different person, probably working in a recording studio or simlar rather than a record manufacturing plant, though it was not unheard of for last minute adjustments to be requested by the artist or producer at the cutting stage.

Edit : for clarity (hopefully)

Mastering Vinyl

Reply #59
Nice idea usernaim but trying to generalise like that is pretty meaningless. At any given point in time the equipment used in pressing plants was not standard. So a wide variety of equipment of varying levels of quality and sophistication were in use across the industry.  I'm talking about up to the end of the 80's when I left the industry, maybe it's more straight-forward now - and say, since the 90's - with volumes being lower and pressing plants fewer.
Also, while cutting a lacquer is a bit of a black art a cutting engineer would never "sum bass to mono", apply eq, compression or anything else without the OK from the artist or producer. The last thing you want is for your test pressings to be rejected and have to re-cut. Any "preparation for production" like that would usually have been done by the mastering engineer who produced the tape from which the lacquer was cut. That would invariably be a different person, probably working in a recording studio or simlar rather than a record manufacturing plant, though it was not unheard of for last minute adjustments to be requested by the artist or producer at the cutting stage.

Edit : for clarity (hopefully)



It is just as difficult to generalize things from the late 80s on. Much of the "new" vinyl from that point on was actually old titles reissued on vinyl. The sources and methodologies used for those reissues vary widely. As for the digital preview, that does not mean the signal sent to the cutting head has to be digitized. Over at Stevehoffman.tv they compiled a list of cutting facilities that had an all analog path between the cutting head and the input feed. It was a pretty lengthy and substantial list.

Mastering Vinyl

Reply #60
Also, while cutting a lacquer is a bit of a black art a cutting engineer would never "sum bass to mono", apply eq, compression or anything else without the OK from the artist or producer. The last thing you want is for your test pressings to be rejected and have to re-cut. Any "preparation for production" like that would usually have been done by the mastering engineer who produced the tape from which the lacquer was cut. That would invariably be a different person, probably working in a recording studio or simlar rather than a record manufacturing plant, though it was not unheard of for last minute adjustments to be requested by the artist or producer at the cutting stage.)


Cutting engineer? Mastering engineer? They used to be the same person. Strictly speaking, they still are. 
Reflect a moment on the LP production process, and from what part the "mastering" engineer took his name.
If you were in the business pre 1980, I'd have thought you'd remember that. Or maybe you're like me - Memory is the second thing to go with age. I forget what the first one was...
Regards,
   Don Hills
"People hear what they see." - Doris Day

Mastering Vinyl

Reply #61
Cutting engineer? Mastering engineer? They used to be the same person. Strictly speaking, they still are. 
Reflect a moment on the LP production process, and from what part the "mastering" engineer took his name.



Yes!  "Mastering' was basically invented because of limitations of the distribution media, and the home systems used to play them.








Mastering Vinyl

Reply #62
Also, while cutting a lacquer is a bit of a black art a cutting engineer would never "sum bass to mono", apply eq, compression or anything else without the OK from the artist or producer. The last thing you want is for your test pressings to be rejected and have to re-cut. Any "preparation for production" like that would usually have been done by the mastering engineer who produced the tape from which the lacquer was cut. That would invariably be a different person, probably working in a recording studio or simlar rather than a record manufacturing plant, though it was not unheard of for last minute adjustments to be requested by the artist or producer at the cutting stage.)


Cutting engineer? Mastering engineer? They used to be the same person. Strictly speaking, they still are. 
Reflect a moment on the LP production process, and from what part the "mastering" engineer took his name.
If you were in the business pre 1980, I'd have thought you'd remember that. Or maybe you're like me - Memory is the second thing to go with age. I forget what the first one was...

Well, where I used to work a tape would arrive in the cutting room that had already been mastered elsewhere. The cutting engineer would then cut the lacquer from that tape. The "mastering engineer" was so-called because he produced the master tape. Maybe you called the cutting engineer the mastering engineer because he produced the master disc - well, he didn't really it was actually grown by electrolysis from the lacquer but maybe that's spitting hairs

Mastering Vinyl

Reply #63
Scott, all flaming aside, I would like to thank you for your detailed criticisms of the page, and I am working through them as I find the time/words to say.

As I see it the two most basic catagories of reasons why the mastering may be different can be divided into two


1. Differences in the signal fed to the converter and cutter preamp.
2. Differences in how any given converter or the cutting lathe that was used will handle that signal.

Differences in the signal can stem form choice of source, equipment used for the source, and deliberate manipulation of the signal ie compression, summing bass to mono, noise reduction, eq, other signal processors etc etc.
Differences in how a given converter or cutting lathe handles the signal can depend both on the equipment itself and the signal being fed to it. One can not forget that over the span of the existence of CDs and vinyl there have been any number of changes and variations in this hardware.

If you start citing specific causes for differences you will end up with a very long article.
.. Eh. I think the complete list of possible differences is going to be very long, but I can't imagine how listing the detailed differences which account for 95% of all mastering cases would be a whole lot larger than the ~7 we're talking about. Some classes of differences, like acceleration limiting in the cutting amplifier and pre-eq in the master to compensate for frequency losses in the cutting/playback process, tend to be ridiculously complex and/or have very obscure behavior at a detailed level, but their general audible effect seems easy enough to explain, as is a basic model of behavior (with a little handwaving of course).

Regardless, I think it's very important to explain to people the down and dirty of what goes on in the vinyl signal chain, precisely because of misapprehensions from both sides of the debate - some people think that there's any sort of purity in what goes on in cutting a record, and others think it's some ridiculously dirty sausage-grinding fest that is wholly unsuitable for the reproduction of audio. The truth is obviously well away from both, and I think that even if only a subset of detailed differences are discussed, all readers will benefit.




I found this link over at Audio Asylum. Looks like a pretty awesome data base of hardware. Might be a good starting point.
http://www.floka.com/cutpage.html

Mastering Vinyl

Reply #64
Well, where I used to work a tape would arrive in the cutting room that had already been mastered elsewhere. The cutting engineer would then cut the lacquer from that tape. The "mastering engineer" was so-called because he produced the master tape. Maybe you called the cutting engineer the mastering engineer because he produced the master disc - well, he didn't really it was actually grown by electrolysis from the lacquer but maybe that's spitting hairs


You weren't at the "master plant", then.

Step 1: Recording (tracking), with optional processing (eq, compression).
Step 2: Mixdown to stereo, with optional processing at track and bus levels.
These two steps were often done by the same engineer. For big productions, there could be separate tracking and mixdown engineers. 

Step 3: Cut to lacquer (and process as required to make it cuttable and trackable).
Step 4: Make several copies of the tape with cutting processing included and distribute to other plants.
Step 5: Each plant would then cut from the tape, make a safety copy and pass the tape on to the next plant in the chain.

(But what often happened was that the plant would keep the original and pass down the safety copy. Several generations later, the result at the end of the chain often sounded nasty.)

Note that the processing in Step 3 had to be done using a lathe. It was an iterative process - set up the processing via best guess and experience, cut, examine the result. If not satisfactory, adjust the processing and try again. Some mixdown engineers did have a good understanding of what was needed and could deliver a tape that required little or no processing. 


Regards,
   Don Hills
"People hear what they see." - Doris Day

Mastering Vinyl

Reply #65
Step 1: Recording (tracking), with optional processing (eq, compression).
Step 2: Mixdown to stereo, with optional processing at track and bus levels.
These two steps were often done by the same engineer. For big productions, there could be separate tracking and mixdown engineers. 

Step 3: Cut to lacquer (and process as required to make it cuttable and trackable).
Step 4: Make several copies of the tape with cutting processing included and distribute to other plants.
Step 5: Each plant would then cut from the tape, make a safety copy and pass the tape on to the next plant in the chain.


To clarify:

Step 1: Recording (tracking). Sometimes eq and/or dynamics processing would be applied here, but usually not so much.
Step 2: Mixdown to stereo, with optional processing (eq, dynamics) at track, bus and stereo mix stages of mixing. Create stereo mixdown master, evaluate, tweak.
Step 3: Create cutting master by applying additional eq and/or dynamics processing to ensure cuttability and tackability

Step 4: Check cutting master to see if it requires additional tweaking to correct problems that only showed up after cutting the lacquer. If needed, go back to step 3
Step 5: Tested cutting masters are duplicated at the central production facility. Safety copy is kept there and other duplicates get sent to pressing plants.
Step 6: Cutting masters are used to cut laquers at pressing plants as they are needed.

none of this is cut into stone, but this is the baseline path from which everybody deviaated if they deviated.



Mastering Vinyl

Reply #66
Step 1: Recording (tracking), with optional processing (eq, compression).
Step 2: Mixdown to stereo, with optional processing at track and bus levels.
These two steps were often done by the same engineer. For big productions, there could be separate tracking and mixdown engineers. 

Step 3: Cut to lacquer (and process as required to make it cuttable and trackable).
Step 4: Make several copies of the tape with cutting processing included and distribute to other plants.
Step 5: Each plant would then cut from the tape, make a safety copy and pass the tape on to the next plant in the chain.


To clarify:

Step 1: Recording (tracking). Sometimes eq and/or dynamics processing would be applied here, but usually not so much.
Step 2: Mixdown to stereo, with optional processing (eq, dynamics) at track, bus and stereo mix stages of mixing. Create stereo mixdown master, evaluate, tweak.
Step 3: Create cutting master by applying additional eq and/or dynamics processing to ensure cuttability and tackability

Step 4: Check cutting master to see if it requires additional tweaking to correct problems that only showed up after cutting the lacquer. If needed, go back to step 3
Step 5: Tested cutting masters are duplicated at the central production facility. Safety copy is kept there and other duplicates get sent to pressing plants.
Step 6: Cutting masters are used to cut laquers at pressing plants as they are needed.

none of this is cut into stone, but this is the baseline path from which everybody deviaated if they deviated.


And which particular masterings of which particular titles can we actually cite as having gone through this specific pathology? Can we name any specific titles? Recording engineers with first hand accounts of the eq and/or dynamics processing? First hand accounts of the creation of the cutting master? First hand accounts of the duplication of the cutting masters at a specific central production facility? Any first hand accounts of duplicate cutting masters being stocked and used to cut masters at pressing plants as needed? What about the equipment used? What specific equipment was used with any specific titles we can trace? These are the questions that need to be answered if we are going to say anything about how any particular LP was mastered. One can find a lot of info in the dead wax that will tell much of the story but even then we need a lot of info from the mouths of the proverbial horses to even begin to know what processes went into the mastering.

And of course many of these questions are just as relevant to a vast number of CDs out there. I highly recomend the Dennis Drake paper about the work that went into the mastering of the Mercury Living Presence CDs he mastered with Wilma Cozart back in the nineties.

Mastering Vinyl

Reply #67
These are the questions that need to be answered if we are going to say anything about how any particular LP was mastered.

Do you have any evidence to suggest Arnold is not right in saying:
this is the baseline path from which everybody deviaated if they deviated.
???

To me it seems you're just trolling again.

Mastering Vinyl

Reply #68
These are the questions that need to be answered if we are going to say anything about how any particular LP was mastered.

Do you have any evidence to suggest Arnold is not right in saying:
this is the baseline path from which everybody deviaated if they deviated.
???

To me it seems you're just trolling again.


1. Why would you ask for evidence for something I have not asserted? Axon was talking about getting "down and dirty" in citing the differences one can find in mastering. Remember this from Axon? " Regardless, I think it's very important to explain to people the down and dirty of what goes on in the vinyl signal chain, precisely because of misapprehensions from both sides of the debate - some people think that there's any sort of purity in what goes on in cutting a record, and others think it's some ridiculously dirty sausage-grinding fest that is wholly unsuitable for the reproduction of audio. The truth is obviously well away from both, and I think that even if only a subset of detailed differences are discussed, all readers will benefit."

So my point isn't to question the baseline path Arny has outlined. My point is to try to make some connection between that outline and what actually went into mastering real world LPs. If one really wants to get "down and dirty" then one has to get specific and gather actual facts. Axon does talk about "detailed differences." What is the connection between this baseline path and the detailed differences in mastering of any real world LP? Without some attempt to make that connection we are not addressing that which Axon is trying to cover in his wiki article.


Now I can actually give you fact filled pathologies of the mastering of several hundred of my own LPs. For the most part there is a substantial disconnect between the actual pathologies of the mastering of those LPs and Arny's baseline path. But that is not meant to say that this baseline path is not the path that many other LPs have followed. Most of the LPs which have a well documented pathology of mastering are of the audiophile/audiophile reissue flavor. Many of the others are from various labels that have gained favor among audiophiles and as a result have been well documented through out the years. I am talking about labels like the Mercuries, London Deccas and RCAs of the golden age of classical recording and other labels like Blue Note and other notables in Jazz. At least we can get "down and dirty" with facts surrounding their mastering and maybe make some corolation between their sound and the mastering that went into them. How can we do that just with Arny's baseline path?  If you want to get down and dirty you have to get down and dirty and disect these things individually based on gathered reliable intel. As it is, Arny's baseline path really tells us nothing about the mastering process of any given LP.


Mastering Vinyl

Reply #69
If one really wants to get "down and dirty" then one has to get specific and gather actual facts.

Do you have any reason to believe that the information provided to you by splice and Arnold (two people I believe are far more intimately associated with the music business than either you or I) about how masters for vinyl were typically created is not actual fact?

Now I can actually give you fact filled pathologies of the mastering of several hundred of my own LPs. For the most part there is a substantial disconnect between the actual pathologies of the mastering of those LPs and Arny's baseline path.

Then why not provide us with a typical example from your vast wealth of information to move the discussion along?

At least we can get "down and dirty" with facts surrounding their mastering and maybe make some corolation between their sound and the mastering that went into them.

So what is keeping you?

Mastering Vinyl

Reply #70
When all else fails good ole ad hominem....so predictable

The only failure here is your ability to be constructive.  You obviously feel that such an article cannot be written in an informative and terse way.  I'm merely suggesting that it may be beyond your capabilities.  Based on what you've said, it is clearly not within your vision.  If this is the case and if you, Arnold, or anyone else cannot find it within yourselves to provide help without it devolving into a food fight, then my best recommendation for you is to leave the discussion.

Isn't this where you stop me from any further posting?

As I have warned you in the past, if you are here simply to bog discussions down with petty arguing (very little of your input on this forum thus far has resulted in anything more than this), then yes, though this time you're looking at a permanent ban.

Mastering Vinyl

Reply #71
As far as the two PDFs that we now have  links to, neither is about how LPs were mastered back in the day.

Somehow this essential point was overlooked.

Don't take this as support for your extremely weak and completely unnecessary off-topic contortion act over EQ and compression, however.

Mastering Vinyl

Reply #72
As far as the two PDFs that we now have  links to, neither is about how LPs were mastered back in the day.

Somehow this essential point was overlooked.

Don't take this as support for your extremely weak and completely unnecessary off-topic contortion act over EQ and compression, however.



One of the questions asked by Axon in his OP was "How can a vinyl master be accurately observed as being the same or different as a CD master?" Can't really answer that question without looking into how CDs were mastered.

Mastering Vinyl

Reply #73
You brought these papers up in a direct response to Arnold's refinement of splice's outline.  If you learned how craft a post with proper quotations and transitional phrases, these things might be avoided.

The bottom line is that we don't need justifications or excuses for posts that have started off-topic conversation.  Be clear, to the point and on topic or don't post.

Mastering Vinyl

Reply #74
If one really wants to get "down and dirty" then one has to get specific and gather actual facts.

Do you have any reason to believe that the information provided to you by splice and Arnold (two people I believe are far more intimately associated with the music business than either you or I) about how masters for vinyl were typically created is not actual fact?

Now I can actually give you fact filled pathologies of the mastering of several hundred of my own LPs. For the most part there is a substantial disconnect between the actual pathologies of the mastering of those LPs and Arny's baseline path.

Then why not provide us with a typical example from your vast wealth of information to move the discussion along?

At least we can get "down and dirty" with facts surrounding their mastering and maybe make some corolation between their sound and the mastering that went into them.

So what is keeping you?



here is something from a few sources about the mercury Living Presence LPs.

http://en.wikipedia.org/wiki/Mercury_Records

In 1955, Mercury began using 3 omni-directional microphones to make stereo recordings on 3-track tape. The technique was an expansion on the mono process—center was still paramount. Once the center, single microphone was set, the sides were set to provide the depth and width heard in the stereo recordings. The center mike still fed the mono LP releases, which accompanied stereo LPs into the 1960s. In 1961, Mercury enhanced the three-microphone stereo technique by using 35 mm magnetic film instead of half-inch tape for recording. The greater emulsion thickness, track width and speed (90 feet per min or 18 ips) of 35 mm magnetic film increased prevention of tape layer print-through and pre-echo and gained in addition extended frequency range and transient response. The Mercury 'Living Presence' stereo records were mastered directly from the 3-track tapes or films, with a 3-2 mix occurring in the mastering room. The same technique—and restored vintage equipment of the same type—was used during the CD reissues. Specifically, 3-track tapes were recorded on Ampex 300-3½" machines at 15 IPS. 35 mm magnetic film recordings were made on 3-track Westrex film recorders. The 3-2 mixdown was done on a modified Westrex mixer. For the original LPs, the mixer directly fed the custom cutting chain. At Fine Recording in NY, the Westrex cutter head on a Scully lathe was fed by modified McIntosh 200W tube amplifiers with very little feedback in the system. Older mono records were made with a Miller cutter head. For the CD reissues, the output of the Westrex mixer directly fed a DCS analog-to-digital converter and the CDs were mastered on Sony 1630 tapes. No digital enhancement or noise reduction was used.

The original LP releases of the classical recordings continued through 1968. The Mercury classical music catalogue is currently managed by Decca Music Group through Philips Records, which reissued the recordings on LP and then CD.

In 2003 Speakers Corner Records began issuing 180 gram audiophile quality LP reissues. The LPs are mastered from 2-track tapes made at the time of the original LP mastering, thus one generation removed from the edited session master used to produce the original LP master and the CD master."

This web page has an amazing wealth of information on the Mercury recordings and mastering of the original LPs
http://www.soundfountain.com/amb/mercury.html

Some information about how the original LPs were cut including citation of George Piros as the mastering engineer

"With minimal editing, the session tape was mastered for LP pressing by the redoubtable George Piros. Using the highest cutting levels he could get by with, Piros found several ways to get cutting levels up and distortion products down. His use of something called "variable groove spacing", proved especially useful in reducing distortion prone inner groove problems. In addition, all details of the cutting process were re-analyzed. The in-house tweaked cutting head boasted a heated cutting stylus and was driven with a custom-designed McIntosh Labs cutting amplifier which allowed higher drive current to the cutting head with lower distortion. Predictably, the variable pitch cutter drive, combined with superb lathes and specially formulated cutting lacquers yielded magnificent results. "

http://www.positive-feedback.com/Issue4/pearsall.htm

Some information about dead wax matrix codes and how they relate to the mastering of the LPs

http://microgroove.jp/mercury/Matrix6.shtml