Dmm metal disks?

[mossboss]

The ever changing crystalline structure found on the copper blanks has been a source of troubles for DMM
There was a lot of work done on the matter so as to find a way of having a stable soft deposit
Unfortunately copper has a tendency to plate as a crystal worst still it changes over a short period of time until lets say its "happy"
When it reaches this happy state it becomes quite hard
Dut it its re aligning of the crystals it gets to the point that it causes chattering when it is cut producing a chip that looks like a very fine toothed saw under the microscope
This holds on to the Nickel like grim death making separation of the Master impossible
Never mind the sound it is bad
The aim of course is to have an amorphous deposit which is hard to achieve in a copper plating bath
The best one can hope for or achieve is extremely small crystals using various additives to the baths which are troublesome
They are very hard to monitor so as to keep them in relative % proportions
Now days with electronic devices one could certainly achieve an ongoing monitoring situation with adjustments on the run so as to maintain additives at correct levels
However the very few people who attempted this found that the additives deteriorate quite quick on an ongoing plating system giving inconsistent results
This than necessitates they removal via a complete renewal of the bath or a complete filtering and treatment of the solution quite a painful exercise
Using the blanks as soon as they were done was one solution but impractical
Storing them in a refrigerator at low temperature was again a partial solution to the problem, it is still used today
Of course the diamond cutting stylus had to be tough enough so as to deal with the problem to the extent that it sits at a 15 degree angle from vertical
This of course bought in whole host of other issues not excluding cutting angle excursion been limiting factor compared to or as against a lacquer
The best blanks still suffer from the very issues mentioned even though a lot of work has been done
This now days is carried out by very few people invariably in house R&D so it becomes a well kept secret
No doubt that if Teldec and Neumann had continued with further development of DMM most of these issues would have been solved long ago
Alas this is not the case so it is up to the few DMM owners who also make the blanks to find various solutions
They have solved or partially solved quite a few of them so DMM cuts are still here with us today
By the way Tarnished copper blanks are easily polished up with Brasso or Silvo, a good alternative is Auto body paint polish, it works quite well, but I am Not sure we want to go back to etching, Ha
Cheers

[cgb]

Hi y'all,

I am a bit stunned about these remarks:

Anything up to 8 dB loss can be occur on lacquers that have been cut and left out of the refrigerator

It's clear to me that cut lacquers deteriorate over time, more so in a warm environment. But a loss of 8 dB? That seems rather exaggerated to me. Please correct me if I'm wrong...

Usually we ship our lacquers daily, they are plated the next day. But sometimes it happens the customer can't decide on a pressing plant or there is some other issue, so the lacquers may stay for a prolonged time. We nearly never had any complaints about those cuts in 17 years.

Also, what use is it to cool the lacquers and then having them going around in a truck in direct sunlight, sometimes being parked there for hours? Aren't these drastic changes in temperature going to be more damaging than a steady temperature, even if higher on average?

There is a loss regardless as the material that has not been "cut" but rather pushed wants to go back where it was pushed from
The cooling down slows that effect down quite effectively

I am not an expert in the field of plating / pressing, but isn't the de-horning supposed to get rid of that? And the stylus heating from preventing it to become too much of a problem in the first place?

Also, some older guys from Neumann / Polygram that I knew never mentioned refridgerating the lacquers, only to store them in a cool place during the summer months (when we still had summers) and not waiting too long to get them plated.

Another guy who used to cut at Teldec / Polygram told me some years ago that they always used the three-stage-plating process with DMM, because they couldn't be bothered with cutting again due to some mishap at a later stage.

So they were giving away one of the core advantages of DMM compared to lacquer.

On the other hand I know of some pressing plants here in Germany that only do one-step-plating with lacquer cuts, due to the small runs of 300 to 500 and to keep the cost down. Might be ok if nothing goes wrong in the press....

On the Scientology issue: I guess the level of quality doesn't have to be that high, it's only spoken words, some recordings may even have been made with a dictaphone or whatever, so a very limited frequency range.

Regards,

cgb

[opcode66]

Also, what use is it to cool the lacquers and then having them going around in a truck in direct sunlight, sometimes being parked there for hours? Aren't these drastic changes in temperature going to be more damaging than a steady temperature, even if higher on average?

I was wondering this myself. For sure FedEx doesn't have air conditioned trucks.

On the Scientology issue: I guess the level of quality doesn't have to be that high, it's only spoken words, some recordings may even have been made with a dictaphone or whatever, so a very limited frequency range.

The quality of most of the recordings are actually quite good. Seems someone knew what they were doing. Also, the group itself had access to a lot of very nice equipment over the years and still do. In fact, they have a top notch production facility for audio and video today.

So, definitely not recorded on dictaphones. It was generally recorded from the board/pa that their mic was plugged into for his lectures. There is usually a bit of intro and outro music. So, mostly limited frequency range. But, at the beginning and end of a lecture the full frequency range would be used.

Interested to see how Philip Seymour Hoffman portrays the man in The Master.

[Aussie0zborn]

... they always used the three-stage-plating process with DMM, ...
So they were giving away one of the core advantages of DMM compared to lacquer.

Maybe, but they still have these advantages:

1. No lacquer springback effect with DMM
2. Less chance of horns with loud cuts
2. Eliminating the silvering process.

These are three big benefits that they still took advantage of.

Using direct stampers (US: one-step process) today is probably justified due to the small runs and no chance of a repeat order. As many plants are owner-operated, who is going to sit down and listen to the mother before making a stamper from it?

[cgb]

As I said, one of the advantages. Also, lacquer has some advantages over DMM, but that's for another time....

Still not sure about that ominous 8 dB loss, though....

Best,

C

[gold]

Still not sure about that ominous 8 dB loss, though....

I'd like to know how this was determined and get some specifics wrt frequency response. 8dB loss is pretty vague.

To test with a phono cartridge you would first have to characterize the frequency response of the cartridge and overlay that on top of the frequency response of the record. Pretty complicated.

Are there any papers on this?

[dubcutter89]

To test with a phono cartridge you would first have to characterize the frequency response of the cartridge...

afaik there is only a loss in the highs. to check that frequency range properly you should use light beam measurements...
maybe i find something...

Lukas

[gold]

afaik there is only a loss in the highs. to check that frequency range properly you should use light beam measurements...
maybe i find something...

Can I see your calibrated light beam measurement system? I don't have one. I'd have to measure the frequency response of a cartridge by using a test record and then comparing that to recorded tones on a lacquer.

[dubcutter89]

Sorry, I don't have one either...

But (in theory!) for a quick test it should be ok to use a torch (or any other spotlight
= parallel light beams), your eyes and maybe a ruler.
This won't give you 100% accurate measurement down to 0.5dB,
but it will give you a good direction...

so if your nominal level makes a light beam of 2" (fresh after cut),
and after storage the highs are down by lets say 6dB then you would
only see a 1" pattern - I guess you don't need a interferometric super device for this...

I have a few papers on light beam measuring of mono and stereo discs published by neumann engineers - will translate them and make a summary when i got the time.

Lukas

[gold]

That sounds way more complicated than my method. We don't need an absolute value. Only a ratio in dB.