100% correct stylus heating

[Nickou]

I have been surprised the first time I saw that on the vms 80 , and I did some test of noise.
increasing the current with the diameter gives less noise.

the heating has not so much effect at the begening of a side , you can cut with nearly no heating and you won t have so much noise , at more than 50 % of the diameter , yes you realy need it if you want a silent cut

[gold]

the heating has not so much effect at the begening of a side , you can cut with nearly no heating and you won t have so much noise , at more than 50 % of the diameter , yes you realy need it if you want a silent cut

Interesting! I always check stylus wear at the inside diameter.

[boogievan]

I have been surprised the first time I saw that on the vms 80 , and I did some test of noise.
increasing the current with the diameter gives less noise.

the heating has not so much effect at the begening of a side , you can cut with nearly no heating and you won t have so much noise , at more than 50 % of the diameter , yes you realy need it if you want a silent cut

Surely it will not be possible to set the stylus heat by ear, listening only for minimum hiss, if the problem doesn't rear its head until the inner radii. There is a correlation between loss of treble fidelity and inner radii since this is where the linear velocity of the blank surface decreases compared to that of the outer radii. In fact, there is a 2 dB loss at around 8 kHz between the first band and the last band on an LP even when using heat on the stylus. It's much worse without heat. But the hiss, which is what one is controlling when adjusting heat, is throughout the side on our planetary systems. hehe


-Tim E.

[Serif]

I think what Nickou was might have been alluding to was an increase in Gaussian noise or hiss with the diameter effects of the spiral's speed you describe, Tim E. There is a distortion in treble loss, but are there also added sidebands when we speak of the noise? Self-erasure doesn't forcibly imply harmonic stacking or revoicing (of partials).

Doubtless, you'll not want to set or increase where horning is forming, and this means cold, as well as too hot, cuts.

Your meter may very.E

- Serif

[opcode66]

On VMS70 this could be done a number of ways really easily that I can think of. You could use one of the fly wheels on the back of the lathe body that has the wire for the carriage. The wheel could be used to drive a multiturn trimmer pot in series with some other resister for form a nice roll up in heat as you get to the center diameters. That would be a very quick and dirty way to get there.

You could alternatively put an optical rotary encoder on it and use a pic programmed to take the setting from the VMS pannel as a base setting and then ramp up as the optical rotary encoder turned so many times. Once the pic registers a Brake/Stop signal it resets to base heat setting.

I've also considered adding a laser to my lathe. That way I could know carriage delta (amount its moved) extremely accurately. This could be useful for a number of things. I won't go into too many details. Suffice it to say, it could also be used for this sort of application.

[gold]

Surely it will not be possible to set the stylus heat by ear, listening only for minimum hiss, if the problem doesn't rear its head until the inner radii.

I haven't seen much of a difference between lacquers of the same batch and very little difference with different batches. I'll check stylus heat as well as stylus wear at the inner diameter from now on. The top side of the first lacquer is usually unusable because of marking from the paper. It would be fine for checking heat.

[gold]

On VMS70 this could be done a number of ways really easily that I can think of.

The easiest way I can think of is to turn the knob.

[opcode66]

I meant in an automated and repeatable fashion of course...

[Nickou]

Yes , you can automat that , or doing it manualy ... it is not so much diificult ... you only have to turn a knob ... it is not a such big deal to automate it ... ( I won t do it)

To boogievan :Yes , frequencie response change with the diameter , with the speed too ... and not only at , or around , 8 k Hz... but in all the spectrum ...we know that ...
Yes you can set that by ear , of course ... and if we do that , it is only because we hear noise ... so ... I use my ears and it is all I need ...

the best is doing test ... if neumann did that , it is probably for something ...
hmm ... 0.3 is ok at the begining of a record and at the end 0.6 or a bit more is perfect ...
if you don t want to change the current during the cut , a current of 0.45 amp is ok ...
If you cut at 45 , you need less current ...

[Hamilton]

Hi,happened like never before in 10yaers a default Adamanta Stylus,at the the end my personal conclusion hope help,the impedance of the Adamant is 3.6 ohm OK waste 4 amp so feed for brilant cutter 1,3/1,6 Volt DC,cutting a record blow a resistor and heat 2.6 Volts and the laquer smoked beware.

Keep on the groove
Hamilton
http://www.hamiltonrecords.com.ar

[Serif]

Hi,

Unfortunately, adding heat during a cut is flirting with both chip fire and the very horning one is trying to preclude by heating the stylus in the first place. One trusts the current meter for reference, but the only way to verify that the heat is not too low is to do a test cut on the lacquer coating under test while listening to the hiss level via the pickup cartridge during cutting.

{From the Westrex 3DII manual: (Section IV, p.3)

"...It is not advisable to use too much stylus heat [awkwardly phrased - of course too much anything is not advisable!...], as this will cause chips to burn. The burned chips may adhere to the hot stylus so tightly that removal is impossible without damage to the stylus. The suction pump must be operating whenever the heater coil is energized; otherwise the chips will burn and adhere.}

One might get lucky for a while if the meter response is consistent and the batch under test is uniform. However, the same batch of lacquers can possibly have variable characteristics. They are packaged normally first in first out, but there's no guarantee of that barring physical differences, as far as I know, as something could change during the creation of a "batch" which renders discs 20-25 different from discs 1-19, wrt hiss or suction success.


While it would be nice to be able to do hiss tests at the inner radii, where the problems of wiggle-packing are confounded by slowing land, one can't really avail herself of that luxury since she needs that land for the cut. The non-preferred side is not quite a perfect test site at inner radii, either, since the ideal heat needed on the non-preferred side could be slightly different from the ideal heat needed on the preferred side since the two sides of the same blank are dried and cured during separate cycles which could have varying effects in the event of different conditions having occurred during manufacturing (in spite of their valiant efforts to preclude such differences).

Whatever heat is applied which is less than that which risks chip burn or horning (which can happen with either too much or too little heat) will still always result in lower treble loss at the inner radii than if heat is not applied (at all). At least one isn't normally doing cold cuts, since that results in a huge droop in high frequency response at the slower radii.

Only setting the heat by ear (for least surface hiss) at the lowest effective setting at the start of the cut is safe and convenient (due to the oversizing of grandmother discs). Any change, other than slightly lowering the heat in the low-fi section of the groove to avoid chip burn or heat horning, if heat runaway is suspected, could poke through to thermal crises. We might infer that a li'l bump of heat is safe, but dishing out that li'l bump, in the heat of battle, after almost a mile of successful revolutions, seems more maniacal, given the risk of overshooting the bump deflection and wrecking the side or the jewel or both.

If you want the music to sound best without risk of destroying a blank, or having chip foul a stylus, don't increase the heat at the inside of the disk - simply cut to more sides without filling up all the land. If treble is your thing, I recommend no more than 1.8 inches effective radius starting at 11.75". Ymmv...

I happen to like the sound of diameter loss as a welcome sonic pillow. My favorite word for tone is "dulcet." While brass horns are usually hard to handle when close-miking is used (and the players should be wearing musician's ear plugs), the last song on one of the sides of Songs in the Key of Life, "Sir Duke," came off loud, proud, but not strident at all. And they obviously finished that side without burns of severe horning... I site diameter loss as the producer's friend... Viva l'atenuación!

-Serif

[boogievan]

Clearly there's less friction at the inner radii which are passing land more slowly under the stylus and this makes the heated cut a little colder at the end of the side if heater coil heat hasn't built up during the cutting of a long side (a big IF...). I think I read that the loss at 8 kHz by the end of a side of a cold cut is around 12 dB versus a loss of about 2 dB @ 8 kHz when sufficient heat is applied. So, heating some tends to swamp the effect of diameter loss, even when no increase in heat is applied compared to the start of the side's setting. Therefore, I agree that, wrt to heat increases during cutting, it might work a treat for those who like to play Jack jump over the candlestick, but the horse has left the barn, since we don't know for sure what the stylus temperature is (and we only suppose that the current meter is holding true), nor do we know what the lacquer's burn point surely is. Since we're working between the rock of too little heat and the hard place of too much heat, we should probably, indeed, just set it and forget it at before the start of cut, unless there's an issue (and then it's too late)... Thanks, Serif.


- Tim E.

[Serif]

Here's the problem with just improving the sound by heat: Too much (or no) heat - as seen at GS:

http://www.gearslutz.com/board/attachments/mastering-forum/325114d1358005193-lead-groove-45-rpm-vinyl-test-pressing-img041.jpg


Same as can happen when no heat is applied, curiously. But at conditions where the outer groove, where friction is higher, still don't thermally sum to make horns, having dialed in the least heat with the best sound, one can be relatively assured of avoiding thermal horning. This is the premastering answer to the problem, as distinguished from the dubbing answer, perhaps.. Since horns only really vex galvanoplasty and pressing.

Serif

[vmspoland]

hi Laquer cutters!

yesterday, I noticed a small problem with my stylus heating circuit,
and finally, I am not sure if it works 100% correctly.
As far as I know, there must be a voltage of 5V DC with an amperage
of approx. 0.4-0.5 Ampere (adjustable). (so, approx. 2 Watts)
But, I measured only 2Volt @ 0.5 Ampere, that´s only 1 Watt.
If I raise the amperage/voltage up to 0.8Ampere @ 2.4 Volt (approx. 1.9 Watts),
the groove is not looking clear anymore. (the valley looks more white)
Then, I leveled the ampere down to 0.2, I had a clear groove...
All was done with transco stylus and apollo laquers.

I am interested in the original regulation circuit for the laquer styluses, anybody
has them? I think, with mine, is something wrong...

Thanks for your help!

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