Troubleshooting: Lacquer rip coming up short

[naive]

Hi everyone!

I'm new here and was referred to this Wonderful World of Vinyl Wisdom by a vinyl mastering engineer I use regularly. He told me you guys would be the surest bet on solving the problem I have.

So here it goes: I ordered a lacquer rip (wav) of a section of a song that had some pitch wobble issues on the first test pressing. I asked the project's vinyl mastering engineer (not the person who referred me here) to have a look at it and run it through Izotope. He told me the issues were way less prominent but still there to some degree. Here's his screenshot:
https://drive.google.com/open?id=1Ko0iS5VNPu2NsRh0fM_Y8fUuUc25tSab

The answer I got from the plant to this was the following:
"Slight vibrato/wobble from lacquer rip are related with small jumps of electricity (it’s never stable 50 Hz in electrical outlet) which causes little differentials in rotating plate during cutting.
This analogy variance is our limitation and best what we can provide assuming that vinyl is perfectly centric."

Now my humble question to you guys is whether what the cutting engineer at the plant is saying is acceptable per se for a professional vinyl plant and whether it's also an acceptable explanation for the wobble issues detected in the screenshot?
Also – and I have no idea if this is relevant for this kind of problem – my go-to vinyl mastering engineer thought the original digital vinyl master employed a bit more limiting than he would put on a vinyl master, but he wasn't able to say whether this could be a source of the pitch wobble problem (as well) or not.

Thanks so much for your help on this!
And if this is the wrong forum, Mods; please feel free to move me and mine!

Cheers,
naive

[markrob]

Hi,

The image you linked to doesn't really tell us much of anything. To make a judgement we would need:

1. An audio sample of the original source material.
2. An audio sample of the rip.
3. Some information on the equipment used by the mastering house to make the cut. Was this done on a VR, Presto, Scully, VMS, etc.? Cut from tape or a digital source?
4. What was used to playback the cut?
5. Were there any problems with the eccentricity of the lacquer during the playback or cutting?

Mark

[naive]

Hi Mark,

thanks for the reply. I'll get the info to the questions I can't answer right off the bat and get back to you!

Cheers,
naive

[naive]

Hi again,

here we go.

1. Audio sample of original digital master: https://drive.google.com/open?id=13wAbotqqMGC383i9nYFRDjJ5u6cifBGI
2. Audio sample of the lacquer rip: https://drive.google.com/open?id=1TcF6qWmJoPwawJo3_FZ9dfPWxUiLc-4h
3. Neumann VMS 70 used for cutting. Cut from digital source (wav).
4. Lacquer checked and played back on Pro-Ject Classic record player with Ortofon 2M black stylus.
5. No problems with eccentricity of the lacquer during playback or cutting.

Thanks so much for the help!

Cheers,
naive / Jon

[boryo]

Scandinavia is far away from California but this is some dope Scandinavian g-funk like music. Who is the artist? I would like to buy that record. Love it!

Best,
Bob

[naive]

Hi Bob,

glad you like it! Here's his Bandcamp page: https://phunkymrolavi.bandcamp.com
He's got a new CD out and the vinyl is...well, almost around the corner

Cheers,
Jon

[petermontg]

Random thought....Misalignment of the punch hole in metalwork?

[naive]

Thanks Peter, I'll add that to the list of possibles!

Cheers,
Jon

[Aussie0zborn]

First things first. Off-centre test pressing usually means that the hole in the centre of the stamper is not exactly in the centre, or the stamper was not fitted to the moulds properly or the moulds in the press are off-centre but more than likely an off-centre stamper. So, I’m not sure why a reference cut was ordered.

Secondly, I’ve noticed that when a half-cut Transco 12” lacquer is taken off the VMS70 and placed back on to make another cut on the same lacquer, the first cut, when viewed through the microscope, is often off centre with eccentricity exceeding 100 micrometers.

This no doubt relates to the size of the lacquer’s centre hole. So, playing a cut lacquer on another turntable would exhibit the same eccentricity, especially if you have pitch-perfect hearing. I didn’t listen to your music.

To date, I have never heard of anybody complaining about off-centre acetates. maybe it’s their playback turntable. Try asking the pressing plant or the stamper maker if they have a stamper eccentricity tester and ask for the measured eccentricity of your stampers.

[naive]

First things first. Off-centre test pressing usually means that the hole in the centre of the stamper is not exactly in the centre, or the stamper was not fitted to the moulds properly or the moulds in the press are off-centre but more than likely an off-centre stamper. So, I’m not sure why a reference cut was ordered.

Secondly, I’ve noticed that when a half-cut Transco 12” lacquer is taken off the VMS70 and placed back on to make another cut on the same lacquer, the first cut, when viewed through the microscope, is often off centre with eccentricity exceeding 100 micrometers.

This no doubt relates to the size of the lacquer’s centre hole. So, playing a cut lacquer on another turntable would exhibit the same eccentricity, especially if you have pitch-perfect hearing. I didn’t listen to your music.

To date, I have never heard of anybody complaining about off-centre acetates. maybe it’s their playback turntable. Try asking the pressing plant or the stamper maker if they have a stamper eccentricity tester and ask for the measured eccentricity of your stampers.

Thanks man, this is really insightful!

I've got to be honest, I can't hear the difference between the original digital master and the test press or lacquer rip, except for the obvious bell curves on the analog playbacks. And I'm a musician who spends a lot of his time at his DAW on all kinds of music, so I would like to think I've got at least somewhat trained ears when it comes to picking up this kind of stuff.

I guess the main thing I'm really trying to figure out is whether the artist has got unreasonably high expectations regarding their vinyl (which, of course, is not entirely uncommon) or whether there's actually some kind of flaw in the production chain of the vinyl itself that I haven't figured out, and that you, the pros, could maybe point me towards.

I just requested a measurement of their stamper eccentricity from the plant. I'll get back to you with their answer!

Thanks so much for the help,
Jon

[naive]

Answer from the plant regarding the eccentricity of the stampers:

"There was a mistake in determining the centrality on the galvanizing - it has already been repaired, which has already been physically confirmed"
I'm guessing the repaired version they're referring to is the lacquer rip from the first post.

So I guess what I'm left now wondering is whether the remaining pitch wobble – that I'm personally unable to hear but is still detectable with software (Izotope) – can be attributed to what the cutting engineer at the plant refers to "small jumps of electricity (it’s never stable 50 Hz in electrical outlet) which causes little differentials in rotating plate during cutting. This analogy variance is our limitation and best what we can provide assuming that vinyl is perfectly centric."

Do you reckon this is an acceptable explanation by the plant?

Cheers,
Jon

[markrob]

Hi,

I did some listening and analysis using my old version of Adobe Audition. As with you, I was not able to hear the issue, but my 63 old ears are suspect. Diving into the spectrum, I was able to see the drift:

The Source file:

Source.jpg

The Rip:

Lacquer.jpg

I used a 16385 point FFT for the measurement, so the frequency resolution is pretty high. The drift is about 5hz peak to peak on a center frequency of about 1Khz. That seems high. Around +/- 2.5% based on the 1Khz fundamental and looks sinusoidal. It seems to happen over about one revolution of the lacquer (1.8 sec at 33.33 RPM). This makes me think its still an out of round issue not normal wow or flutter due to random mains variation.

It would be interesting to have them cut a 3150 hz tone to a lacquer and run the cut through a wow and flutter meter to try to get more quantitative numbers. Even doing that is open to interpenetration as you will be measuring eccentricity, wow, and flutter on the lathe and playback turntable combined.

If you are interested, I developed a software (PC based) wow and flutter meter that I can provide that may be helpful. I haven't vetted it against a commercial hardware meter, buy as best I can measure its accurate. It has a scope view so you can see if the pitch variations are cyclical or random.

Mark

[naive]

Mark,

I can't thank you enough for digging into the nuts and bolts of this (is there a way I can buy you a beer?!?)! This is truly a huge help. I've just e-mailed the plant with your findings and it'll be interesting to hear back from them. With the equipment they're using you'd think they'd be able to get this sorted.

Does your Wow and Flutter metre software work on Mac as well? It seems that a software like yours or the Izotope/Adobe ones might come in handy if I continue this dive into the world of vinyl...

I bow my head in Thanks to you,
Jon

[markrob]

Hi,

Sorry, the program is PC only.

Also, a correction. 5hz out of 1000 hz is +/- .25%, not 2.5%. So the error is not that bad. Probably why I can't hear it give the program material. If it were solo piano, I'm sure it would be much easier to hear. .25% is still a bit on the high side for a pro setup, but if I'm right that this is some sort of "out of round" problem, its more likely mechanical rather than mains based. Still might be good to do a wow and flutter test of the lathe.

Do you know if the lathe motor is a DC servo or AC synchronous type?

Mark

[naive]

Alright, pity about the software. Would've loved to try it!

I've just sent them the question concerning the lathe motor.

Thanks again,
Jon

[handcut]

It seems that a software like yours or the Izotope/Adobe ones might come in handy if I continue this dive into the world of vinyl...

+1 for Adobe Audition. I've been using it since it was called Cool Edit back in the late 90's. Great wave editor with excellent analysis tools such as the spectral editor Mark has demonstrated. Runs VSTs. Very stable (on PC anyway). I believe there's an Apple version now... Only downside is you have to buy in to the Creative Cloud nonsense...

[naive]

It seems that a software like yours or the Izotope/Adobe ones might come in handy if I continue this dive into the world of vinyl...

+1 for Adobe Audition. I've been using it since it was called Cool Edit back in the late 90's. Great wave editor with excellent analysis tools such as the spectral editor Mark has demonstrated. Runs VSTs. Very stable (on PC anyway). I believe there's an Apple version now... Only downside is you have to buy in to the Creative Cloud nonsense...

Oh man, I hate that cloud bull... I want to actually own my stuff and not pay for it indefinitely. Maybe I'm old school that way... But I'll give it a look nonetheless, thanks!

– Jon

[naive]

Thanks so much for the help so far guys!

The cutting engineer just sent me ("the customer" in this message) the following message:

"If the customer thinks that it makes sense, we can send him also post-production varnishes used for production. He will be able to compare vinyl to production varnish."

Can anyone tell me how this would be of benefit to me? I can't see it myself, but maybe someone can enlighten me?

Cheers again,
Jon