GZ Vinyl in the Czech Republic

[gold]

I'll ask the question again. What is the spec in dBm I am looking for? Should I be measuring wide band response, A weighted, C weighted? How do you quantify impulse noise like crackle?

[opcode66]

It is so much simpler than all that. You could simply watch a VU meter.... Adjust the heat until you see the most minimal reading. Not rocket science my friend.

[gold]

IAdjust the heat until you see the most minimal reading. Not rocket science my friend.

If there is no spec and I always adjust for lowest noise how do I know when there is too much noise? Are you sure I'm always supposed to adjust for lowest noise?

[opcode66]

Seeing as though too much noise is not what you are going for.... This is a best case scenario man. I think that is the point. Saying there is no standard so why bother trying to reduce it would represent the shortest and laziest path. I would hope that your standards are like my own. As high as possible given the circumstances.

So, back to being realistic. Adjust the heat until your monitoring indicates the least amount of overall level from playback. Capiche? I think that is what GZ is saying and asking for.

[gold]

Seeing as though too much noise is not what you are going for.... This is a best case scenario man. I think that is the point. Saying there is no standard so why bother trying to reduce it would represent the shortest and laziest path. I would hope that your standards are like my own. As high as possible given the circumstances.

So, back to being realistic. Adjust the heat until your monitoring indicates the least amount of overall level from playback. Capiche? I think that is what GZ is saying and asking for.

Let me get this straight. There is no standard but I should keep the highest possible standard. I love making up my own standards. They are always right. I now don't have to worry about too much heat and producing horns. That's great I'll keep that in mind and cut the unmodulated groove.

[concretecowboy71]

We adjust heat every time we put a new stylus on. We run heat at .4 .45.5 .55. .6 and listen back for the lowest noise floor.

This method has yielded good results and we have never had a complaint about noise.

Checking groove depth on the outside of a 14" lacquer does not work so well for me, the outside is usually not flat and I find the depth changes on some lacquers as you get closer to the center. I set my cutting depth on the fly under the scope after the head drops and before I start the music. Not hard to do after some practice.

The standard I apply is Joe Meek's..."if it sounds good...it is good". We all use our ears and to me that is the best judge for noise floor.

[opcode66]

Thank you Clint. Another realistic person...

Paul, thouh there is no standard for noise you should be cutting to the height of your own personal standard. Do you get it now? Or possibly you just don't care that much???

[dubcutter89]

I guess Paul is talking of the compromise between least noise and clean grooves free from horns - That's 2 things that don't have to meet...
Also to watch the needle for least "output" may also not get best noise figure: Assume a system with some gear-noise or a slight signal hum at low frequency (ie 50/60Hz). This low frequency noise can be above wide band groove noise and keep the VU needle above a certain level no matter how good or bad heating is adjusted...

Just some food for thoughts...

Lukas

[opcode66]

I am simultaneously watching the grooves as I monitor them to dial in either heat or depth of cut. I also inspect after cutting with the platter stopped. All is accounted for... Both noise floor, groove walls and tops (horns if cut poorly). There is a sweet spot. It is not one or the other. I am using my ears to determine noise floor as is Clint it seems.

[gold]

I am using my ears to determine noise floor as is Clint it seems.

Do you send your ears with the blank groove? I still don't understand how cutting blank groove helps GZ with outside lacquers other than in a touchy feelie "I do it because I care" kind of way

[concretecowboy71]

I heard Van Gogh sent an ear in!

I don't see much need for the extra groove on the out side. I usually do a short drop on the outside to check my chip pick up, but I don't rely on it for anything substantial.

[opcode66]

No I don't send my ears. That would be ridiculous.

Do you package a scowl and sarcasm in with yours?

[mossboss]

Well that's a nice thread aright, lots of scepticism by some good input from others,
Really what's the big deal over a simple step in the whole scheme of things?
It seems that this thread has now taken a life of its own
Todd
You are admitting the variation in thickness on any or some lacquers and yet you don't adjust heat per lacquer, is that so?
Have a a bit of reflection, would the stylus cut through the thicker part the same as the thinner part?
Also, the production batch number may be a good indicator of consistency but our experience has shown otherwise
Best

[gold]

Really what's the big deal over a simple step in the whole scheme of things?

I think it should be a requirement to incorporate a pirouette and a downward dog in to the lacquer cutting routine as it helps keep everyone in tip top shape to cut the best lacquer possible.

[mossboss]

Argh Paul, what can any one say here?
Best

[opcode66]

Todd
You are admitting the variation in thickness on any or some lacquers and yet you don't adjust heat per lacquer, is that so?
Have a a bit of reflection, would the stylus cut through the thicker part the same as the thinner part?
Also, the production batch number may be a good indicator of consistency but our experience has shown otherwise
Best

You missunderstand. don't mean a variation of the thickness through diameters of an individual disc. I mean a variation in thickness from disc to the next in the same box with the same lot number. In that respect, you would certainly end up with grooves that were either more thin or more thick from one disc to the next without adjusting cutterhead height. Therefore, the groove width check on each master cut.

If the discs are being rushed out the door then they would have less consistency in their individual coating thickness from disc to disc in the same production run. However, the lacquer compound being used was likely just prepared for that run specifically. So, one can safely assume that the consistency of the lacquer compound is more reliable than the thickness of it from disc to disc in the same run. Now, one can take those two pieces of data and synthesize the following conclusion (knowing that the heat required is more of a factor of the exact compound than its thickness). It is more important to check depth (groove width) from disc to disc than it is to check heat within a sampling from the same box and same lot number.

I think it should be a requirement to incorporate a pirouette and a downward dog in to the lacquer cutting routine as it helps keep everyone in tip top shape to cut the best lacquer possible.

Until you can achieve this, all the rest is pedestrian.

[mossboss]

Fantastic well done
I suppose you did this pirouetting, as some suggest one ought to do, and please tell me, did you do this having some kind of a dog hanging around?
Best

[opcode66]

Done

[GeorgeZ]

Nah none at all, just like GZ, neither of us have a clue
Best

What is the noise spec I am going for when I adjust the heat per lacquer? How do I measure to make sure I meet the spec?

We use Neumann RUMS 77 (with the A curve added as an external filter) and Sennheiser UPM 550-1 units for noise measurements.

RUMS 77 can be seen here:
http://www.preservationsound.com/wp-content/uploads/2013/09/Gotham_Audio_1979.pdf
http://lcweb2.loc.gov/master/mbrs/recording_preservation/manuals/Gotham%20Catalog%20%281981-1982%29.pdf

Sennheiser UPM 550-1 can be seen here:
http://app.sennheiser.com/sennheiser/old_manual.nsf/resources/UPM_550_oNr_1179_Sp3.pdf/$File/UPM_550_oNr_1179_Sp3.pdf
Measurement is done with the A curve on and using effective RMS values.

Best values for Cu plates are -74 dB on 40um grooves and around -70 dB for lacquers. Values up to -60 dB are considered acceptable for lacquers (often between -65 dB and -68 dB) and for wide grooves on Cu plates. Higher noise is claimed or we cut again (internal claims).

Similar results are obtained using our software metering on digitized signals through DA converters.

[gold]

We use Neumann RUMS 77 (with the A curve added as an external filter) and Sennheiser UPM 550-1 units for noise measurements.

Best values for Cu plates are -74 dB on 40um grooves and around -70 dB for lacquers. Values up to -60 dB are considered acceptable for lacquers (often between -65 dB and -68 dB) and for wide grooves on Cu plates. Higher noise is claimed or we cut again (internal claims).

The RUMS77 is for measuring low frequency noise (rumble). I have an RUMS 75. When adjusting heat on a lacquer you are mostly listening for high frequency noise, although low frequency noise is affected somewhat. Rumble is more of a constant for a particular system in my experience. The numbers above seem right to me and would be what I would expect.

I am not aware of a standard way of measuring high frequency stylus noise or crackle. Using your best judgement is the only way I'm aware of.

I'm not familiar with the Sennheiser unit. It looks like the UPM 550-1 is an AC level meter with a bunch of different weighting curves. Nice unit. I guess A weighting is as good as anything else for an all inclusive noise measurement. The Neumann VG66 doesn't promise better than -65dBM