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JayDC
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CV for pitch and depth on mastering lathes

Post: # 14459Unread post JayDC
Thu Apr 21, 2011 6:48 pm

anyone have any information on this, I am working on a piece of hardware to control this on my presto, and i want to make sure it works with other lathes too.

the system i'm designing outputs 0-5V analog. which will control the servos that will eventually automate my overhead. I would guess vms lathes use the same idea..

i <3 my new basic stamp kit :D
generally its for reproduction.. but i like to play wif it sometimes.. :P

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opcode66
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Post: # 14461Unread post opcode66
Thu Apr 21, 2011 7:18 pm

Depth control on the VMS is measured in milli-Amps. So, it is variable current, not voltage.
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JayDC
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Post: # 14462Unread post JayDC
Thu Apr 21, 2011 7:33 pm

ok cool.. how about the pitch?
generally its for reproduction.. but i like to play wif it sometimes.. :P

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opcode66
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Post: # 14471Unread post opcode66
Fri Apr 22, 2011 1:35 am

Pitch is voltage controlled. But, it is variable and computer controlled. Three movements are calculated: lateral as the result of lateral, lateral as the result of vertical and vertical movement of the cutting stylus are predicted and accounted for in order to change the pitch voltage and thus pack grooves as tightly as possible. The voltage therefore changes in accordance with a preview signal that is sent to the picth computer ahead of the program signal that is amplified and sent to the cutterhead. A new Pitch/Depth computer is one project I'm currently working on. :wink:

Are you modeling a system after a VMS for other lathes? I'm just thinking that it is unlikely anyone with a VMS would replace the their depth control. And, unless you are making a variable groove system, a fixed pitch replacement would also not be a draw for a VMS owner.
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JayDC
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Post: # 14475Unread post JayDC
Fri Apr 22, 2011 2:00 am

its a variable pitch computer, that allows for fixed pitch selection, also incorporates 24bit 192k AD conversion with tos optical or standard 1/4" analog input.

I dunno if it'll run a vms or not, i am planing to make a kit to retro fit old presto lathes. Automated overhead, crystal locked turntable speed, stylus heat control, and stereo preamp with feedback control and monitoring.

Planned to fit in 19" rack mount, optional motor and servo package.

I dont own or have access to a vms, it would be nice to have this unit work with them too though.

this along with a caruso, and some amps will make complete mastering lathes out of presto 6 and 8 series machines..
generally its for reproduction.. but i like to play wif it sometimes.. :P

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opcode66
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Post: # 14484Unread post opcode66
Fri Apr 22, 2011 11:03 am

All variable pitch systems are fixed pitch if no preview signal is supplied.

I'll say to you what everyone has said to me. Good luck. It is some tricky math. Do you know any of the calculations? They aren't in the AES anthology... I'll tell you that. Were you going to empoly peak to peak comparison or realtime point to point?

I've been tinkering on my project for 6 or 7 months. I do everything is c or assembly language. PicBasic is slow slow slow.

You are going to have a tough time trying to make a system that could go on older lathes as well as a VMS. And, I think it would be doubly hard if you don't actually have a VMS. For instance, saying that pitch is controlled by a single voltage is a simplification.

Another point that everone on the board stuck me with repeatedly is that this has all been done before. Blah blah blah. Pitch98 from Vinylium and Zuma pitch computers exist so why try to make another one. Especially since those have been around for 10 plus years and have all that dev time put into them.

I say why not? And, why not do something different or more. That is why I'm moving forward with the design I proposed. The direction I'm going in now will actually be doing something that hasn't been done before and will allow for features never offered on any prior system.
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JayDC
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Post: # 14491Unread post JayDC
Fri Apr 22, 2011 12:31 pm

umm as i said previously, the main intent is to retro fit older lathes.

zuma and pitch98 cost majors dollars.. i plan to price around the idea of the caruso.

motor and servos will cost extra.

My system will probably be a more simple design then those. My theory is to have it react like a vu meter to control the pitch, and the input delay on the head output based on the turntable speed.

then have a selector for 88 112 120 160 etc.. lpi's if you want a fixed pitch instead of a variable pitch and a mono switch on the preamp for people still using grampains etc..

Lead-in, Lead-out, Lock groove, and space buttons, with adjustable space width.

I really could careless if this is needed or not, since in reality, i am only doing this for myself.

You can nay say all you want, it will not discourage me.. So I could really care less on your opinions if i should or not.

since caruso is going to fit presto's, why not make them capable of cutting a good master.

and i never said a steady voltage.. I said 0-5v analog, which is what CV is referring too. analog means its variable voltage.. not ttl, or digital or 5v on and off..
generally its for reproduction.. but i like to play wif it sometimes.. :P

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opcode66
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Post: # 14500Unread post opcode66
Fri Apr 22, 2011 6:19 pm

Wow, man. A little defensive. I didn't nay say you at all. In fact, I wished you luck. Did I say you shouldn't do this? No. Read my post and tell me where I said don't do it. Why be a jerk to someone who is encouraging you and could actually help you? A direct quoute is "I say why not?".

Read my post again. I said "single" voltage. Not "steady" voltage. So, the minor lecture on what variable voltage is was totally unecessary. Before I bought my lathe I invented/designed/fabricated custom MIDI hardware. I've created my own MIDI to CV/Gate converters. So, you're right, I have no idea what variable voltage is. Certainly not from 0v to 5v. You must be genious to understand that...

Whatever man. Your idea is slightly flawed and would never work with stereo cutterheads. It doesn't account for the movement of the stylus. But, that's ok. Obvisouly you grasp all that since you are the master of variable voltage.

I won't bother to continue to respond with relevant info to your posts.
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JayDC
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Post: # 14505Unread post JayDC
Fri Apr 22, 2011 7:58 pm

dood.. cv/gate is a variable voltage analog signal.. just like how my old 303 was driven from a computer via a converter..


if you need to refresh your memory:
http://en.wikipedia.org/wiki/CV/Gate

and i'm pretty sure, my idea is not flawed, just coz its simple..

we are talking about a squiggly line that is spiraled, and can't collide with itself. Like the old game "snake"..

it's not rocket science..
I won't bother to continue to respond with relevant info to your posts.
do you ever? I mean every time you try to act like a know it all, and you lace negativity in your posts all the time.. no offense, I just wanted to know how it works.. just coz ur working on a similar piece of gear, doesn't mean you have to try to shoot down my simple method..
generally its for reproduction.. but i like to play wif it sometimes.. :P

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opcode66
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Post: # 14507Unread post opcode66
Fri Apr 22, 2011 9:01 pm

JayDC wrote:dood.. cv/gate is a variable voltage analog signal.. just like how my old 303 was driven from a computer via a converter..
dood... I know. That was entirely my point. I understand what variable voltage is and even how to generate it under computer/pic control.
JayDC wrote: if you need to refresh your memory:
http://en.wikipedia.org/wiki/CV/Gate
Nope. Know what it is. I've got my custom midi to cv/gate converter hooked up to an sh-101 right now in my studio. That is how midi notes get translated to the pitch control voltage. 1 volt per octave. each note = 1/12 V step up. 5 octaves = 0 to 5V DC.

If you want to make a p/d system you will need to generate a variable voltage form a pic. Sounds exactly like what is done in my cv/gate converter doesn't it??? dood...
JayDC wrote: and i'm pretty sure, my idea is not flawed, just coz its simple..

we are talking about a squiggly line that is spiraled, and can't collide with itself. Like the old game "snake"..

it's not rocket science..
For lateral mono (not Edison Hill and Dale), I suppose you are right. However, there is another component which is depth. Depth adds to the lateral space required for a groove. In a 45/45 stereo head this becomes more of a factor since there is more than lateral movement in response to the program signal.

I was in fact encouraging you to make your system. I was trying to pose questions to you to put you on a good track. And, I've even given you pertinent information. My previous post on 4-22 at 10 am reads pretty clear.

Clearly I don't know it all. Why else would I be on this board?
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Post: # 14521Unread post markrob
Sat Apr 23, 2011 11:04 am

Hi Guys,

I'm interested in the method to do this. Have you seen US patent 4157460? This is a modern digital approach to the problem (1979), with very detailed flow charts and block diagrams of a possbile solution. Looks very easy to implement and expand on with current technology. It also lists most of the prior art on the subject. I'm sure that with current higher speed CPU's, you could eliminate most, if not all of the external analog circuitry shown in the patent. If you plan to market a solution, you would need to do some digging to make sure you are not re-inventing and/or infringing on prior art. For a one off system, feel free to pillage as needed.

Mark

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JayDC
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Post: # 14525Unread post JayDC
Sat Apr 23, 2011 3:32 pm

markrob wrote:Hi Guys,

I'm interested in the method to do this. Have you seen US patent 4157460? This is a modern digital approach to the problem (1979), with very detailed flow charts and block diagrams of a possbile solution. Looks very easy to implement and expand on with current technology. It also lists most of the prior art on the subject. I'm sure that with current higher speed CPU's, you could eliminate most, if not all of the external analog circuitry shown in the patent. If you plan to market a solution, you would need to do some digging to make sure you are not re-inventing and/or infringing on prior art. For a one off system, feel free to pillage as needed.

Mark
werd.. tis sounds cool..
generally its for reproduction.. but i like to play wif it sometimes.. :P

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JayDC
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Post: # 14719Unread post JayDC
Mon May 02, 2011 3:55 pm

little update:

2 servos are working, and i have them controlling the head up and down leaver, and the overhead engage knife on my 6n.

I have also programmed the lock groove code.. Works well..

waiting for the 4x20 LCD, and a stepper motor, so i can continue.

going to start coding fixed pitches, then move into a variable pitch.

after that its on to controlling a new TT motor.

then its on to the preamp section, figured out a method to control analog vu meters with a switch to select vu/ppm..

photo's soon, i'm getting a new phone this week, it should have a camera...
generally its for reproduction.. but i like to play wif it sometimes.. :P

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subkontrabob
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Post: # 14729Unread post subkontrabob
Tue May 03, 2011 4:30 am

JayDC wrote: I have also programmed the lock groove code.. Works well..
Now that's a useful feature! I managed to screw up the final locked groove on one of the cuts I did during the last session. A few cm missing to complete it. :?

Very annoying. And I thought I had already mastered this part of the process. Same old lesson: concentrate and focus, keep the Zen/Flow/Force and don't let anything distract you........

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JayDC
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Post: # 14737Unread post JayDC
Tue May 03, 2011 10:15 am

yea I feel ya.. I made a mark on the platter mat with a paint marker, so i could watch for one rotation. I feel automating this will save us presto users styli. Also will allow us to cut those cool locked groove records, where all the tracks are locked grooves.

I might take off the servo controlling the overhead knife, since once the feedscrew is controlled via a motor, there is no need to touch the overhead, except to change styli. I can program the motor to control forward and backward movement of the overhead. Which will allow o/i i/o cuts, and will also move the overhead to the rest position when the tasks are completed.
generally its for reproduction.. but i like to play wif it sometimes.. :P

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cymbalism
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Post: # 14738Unread post cymbalism
Tue May 03, 2011 10:29 am

Sounding positive jay!

If you get them fully functioning and easy to install I might take you up on three of em :)
all the best!
- tommie 'plan 9' emmi
poly-cut lathe cuts / cymbalism recordings

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Post: # 14741Unread post monkey1553
Tue May 03, 2011 6:16 pm

Nice work Jay! Continue to keep us updated!

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JayDC
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Post: # 14750Unread post JayDC
Thu May 05, 2011 12:55 pm

cymbalism wrote:Sounding positive jay!

If you get them fully functioning and easy to install I might take you up on three of em :)
actually working on a way to control multiple lathes with one unit..

Although, not exactly sure how to have the preamp react to this, since i wanted to have the ability to control the feedback. The automation is the easy part.

The easy answer to this would to add in the manual something that states to not use the feedback control on the preamp, and then split off the preamp outputs to each lathe, using a little mixer to add feedback to each head individually.

I guess the question is:

What happens if you take the feedback from head1 and apply it to head2 and 3.


I am under the impression that each head is a little different, and this is not the best option. The easy way would most likely yield a better, result.
generally its for reproduction.. but i like to play wif it sometimes.. :P

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