Is That New Vinyl Release Truly Analog?

[MylesBAstor]

Even if it says mastered from the the original master tapes? And kept in the analog domain?

Sadly not necessarily!

Another complicating factor that I was reminded of by a conversation with Chad on Monday.

Is the mastering engineer using a digital delay line to space the grooves? Then the LP isn't analog. (See Ultratape thread for a picture of Chad's specially built Ampex ATR-102 machine.)

We know Chad's reissues are the real deal. I assume Bernie Grundman's cuts are pure analog. MOFI? But how many others are?

I attached an article from Mikey outlining the issue too!

[david k]

Thanks for that, it does explain a lot.

david

[squasher]

The cutting of the lacquer is still done with the signal fed from the repro head of the Mastering tape deck, right? (i.e. an analog process).

Please explain to me how the insertion of a digital process to control the spacing of the grooves compromises the sound quality?

Other than no longer being able to call it an "all-Analog process", I can't fathom how this would change the quality of the signal that you extract from vinyl playback. Please educate me....

[MylesBAstor]

OK I'll assume everybody knows about why grooves need to be spaced apart eg. low frequencies require wider grooves.

In the old days--or say in the case of D2D recordings--the mastering engineer stood by the lathe with sheet music and adjusted the spacing of the grooves manually. Today, the grooves are automatically spaced using a computer attached to the cutting lathe. To do this, a preview signal is sent "ahead" of the main signal so the computer can analyze the music and adjust the groove spacing for the upcoming musical passage.

Scenario 1: The signal is first converted to digital, split in two with one part going to the workstation and computer and the other, digitally delayed, to the cutting lathe. This of course involves a A-->D and D--A conversion step before cutting the lacquer.

Scenario 2: A special tape machine with two sets of output heads and electronics is used. The tape passes over the first set of heads and that signal is fed to the computer to adjust groove spacing. Then using the right spacing between head blocks and appropriate delay, the tape then passes over a second set of heads whose signal is fed to the cutting lathe.

Hope that helps.

PS. IIRC also anything cut DMM using a digital signal. So now one wonders whether the "brightness" of DMM pressing is the actual process or because of the A-->D and D-->A conversion.

[Bill Hart]

If i'm reading this correctly, Myles, you are saying that the digital preview process, which controls the lathe settings, affects the sonics. How do we know that in this arrangement, the signal being fed to the cutter for inscription into the grooves was subject to digital conversion? Can't a feed for the preview process be digitized for that purpose, but the signal for inscription still come from the tape, i.e., remain in the analog domain? If that is so, then why would setting the lathe parameters digitally affect the sonics in a dramatic way if the signal to the cutting head itself remains in the analog domain and is never converted to "D"? Or am I tripping here? You seem to be suggesting that to digitally preview the signal fed to the cutter must be converted to 'D' for both purposes- preview for setting and for cutting the grooves.

[squasher]

Scenario 2: A special tape machine with two sets of output heads and electronics is used. The tape passes over the first set of heads and that signal is fed to the computer to adjust groove spacing. Then using the right spacing between head blocks and appropriate delay, the tape then passes over a second set of heads whose signal is fed to the cutting lathe.

Yes, of course Scenario 1 is not ideal.

Who cares whether the groove spacing process in Scenario 2 is done digitally or in the analog domain?

[squasher]

Bill's question is exactly as mine but stated in a different way.

[david k]

From what I understand (not quite sure), in this case the digitized signal is what get's converted to analog by the cutting head and not the original analog master.

david

[MylesBAstor]

Or the digitized signal is reconverted to the analog domain and that signal is then fed to the lathe.

[MylesBAstor]

If i'm reading this correctly, Myles, you are saying that the digital preview process, which controls the lathe settings, affects the sonics. How do we know that in this arrangement, the signal being fed to the cutter for inscription into the grooves was subject to digital conversion? Can't a feed for the preview process be digitized for that purpose, but the signal for inscription still come from the tape, i.e., remain in the analog domain? If that is so, then why would setting the lathe parameters digitally affect the sonics in a dramatic way if the signal to the cutting head itself remains in the analog domain and is never converted to "D"? Or am I tripping here? You seem to be suggesting that to digitally preview the signal fed to the cutter must be converted to 'D' for both purposes- preview for setting and for cutting the grooves.

Yes, because there's only one set of heads and the signal must be delayed (around 0.9 sec) to allow the computer to adjust for the coming musical passage. Hence they use a digital delay line. I guess it's kinda like that 5 sec delay they use on radio.

Maybe there is another way but these are the only two ways I know of that are currently being used.

Hope that answers the question.

[MylesBAstor]

Yes, of course Scenario 1 is not ideal.

Who cares whether the groove spacing process in Scenario 2 is done digitally or in the analog domain?

Theoretically maybe but in reality it isn't done that way because the mastering engineer needs to delay the signal sent to the cutting lathe.

[MylesBAstor]

From what I understand (not quite sure), in this case the digitized signal is what get's converted to analog by the cutting head and not the original analog master.

david

Yes and delayed in time to allow the computer to do its thing.

[MylesBAstor]

Also look at the attached piece about Masterdisk.

[Johnny Vinyl]

I would never question the method or the belief of it, but it sounds to me like a case of splitting hairs. How this somehow would be audible is beyond my comprehension.

[david k]

I would never question the method or the belief of it, but it sounds to me like a case of splitting hairs. How this somehow would be audible is beyond my comprehension.

Something is always lost in translation!

david

[squasher]

This discussion is fascinating but has become confusing because we all are
1) reading different things from the original article,
2) making assumptions about where the A/D, D/A processes are occurring
3) don't know enough about the Mastering process.

I'm guilty of all of the above.

Scenario 1: If this is truly the way most Mastering is accomplished, I see the whole point of Myles's original post and understand why we should care about this. I do wonder, however, in this case where the A/D and D/A processing occurs. Is it in a box that sits between the Mastering deck and the Cutting lathe or is it all in the Cutting lathe? What are the inputs to the cutting lathe?

Scenario 2: This was where I am confused. I had assumed the "purists" were arguing the subtleties between using an all-analog process to determine the groove spacing versus calculating the spacing digitally. There are such things as analog computers after all..... The cutting of the lacquer is still done with the analog signal from the repro head. If this is the argument (digital vs analog spacing calculation), I don't know why it matters other than to say it's "all-analog" and satisfy the Mikey Fremer's of the world.

[Johnny Vinyl]

Guilty as charged. Learning more however.