New Pitch Computer

[opcode66]

I am researching how the systems work. I have the tech specs for VMS70, ZUMA as well as the AES anthology vol. 1.

I don't understand why everyone is approaching me like this. Yes, clearly I don't have the knowledge you all have. Otherwise I wouldn't be asking questions or making posts. So, why not share what you know instead of pointing out what I don't?

If I want to make a pitch computer for myself who cares? Why tell me no don't do it? Why try to put a brother down?

I want to understand the process to a finite degree. That is why I'm doing what I'm doing. I could care less if I never sell one. I do quite well at my day job. And, I already have a design for a MIDI device that I'm in the process of patenting and selling. So, I am by no means looking at this as a business. To be honest, I've purchased a VMS70 from Al and it wouldn't matter a lick to me if I never make a dime from it. This is a passion for me. And, I will continue to pursue my passion regardless of who tells me not to.

It only makes sense for me to figure out the nuts and volts (pun intended) before getting into the technical end of pitch computation. It's been a minute since I've tried to do ADC on a pic which is undeniably part of a pitch computer. So, why not get this figured out first?

Since I'm only getting dumped on for my current efforts I will stop posting to this particular thread. I will keep my work to myself.

Thanks,

Opcode66

[d]

Hey,

it seems the world goes that way....

Someone say - go do it, others - you will never gonna make it so stop shittin around.

I wish I could help, but i have not much information about it, maybe you have already most of it.

I think if you want to do it - do it and don't listen other telling not to!
If you are working with uC and similar stuff you know your possibilities.

I really wish you best luck.

[mossboss]

Hey Opcode
Dont do that mate Pleeeeease
I would not be to worried about some of the comments that have been posted here
It goes something like this:
If one has parted with $10-12 k and there is a better mouse trap out there or coming up they feel somehow that they should protect that investment withholding information as well as being self protective
It is to be noted that most comments come from people that have a pitch computer already and an expensive one at that
It no different than some people paying $25 K for a Fairchild compressor because it is that and it has the unobtainable factor built into the price
So any one that has one boasts about it No?
What does that tell you?
There are quite a few of us out there who are fully supportive of your efforts following your post's as well as other comments which I may say may not seem to be encouraging
However
Paul Gold has pitched in Dietrich has I think I have and I can assure you there are quite a few others out there closely watching this thread
Be assured of that
I have 3 off VMS 70's 4th one coming up so here you are I am in regardless of any comments made so far by others
I trully believe you got more than a grip on it and you are asking the right questions however you are getting quite a few answers ((as well as the justification why it should not be done by you or anyone else for that matter), (crap))
If some people have shot this down Let me tell you this, in their post's they have also let out quite a few usefull bits as well
I would not worry about some comment about the 14 Years that Neumann spend developing the pitch for the VMS 80 it is a whole load of crap
They had it loooooong before, but Zuma filled the gap so there was no market for existing systems so it come out on the short lived 80 as not even an option it was part and partial of the machine
Now I can get you in touch with a few people who can give you the very low down on this, every aspect, the ins and outs the full catastrophy
They have been working on this for a very long time as a part time project
To the extent that there is a full vms 80 rack available to friends (I qualify) built by them as recent as 2 years ago (only a couple)
Tested proven with high quality modern components all at a spec much higher than Neumann ever did as they where not available than and it sounds like it to
So here is an incentive for you to keep posting my friend
Also pm me if you wish
So please do not stop
Cheers

[mossboss]

Hey Opcode
It's started already man
In two hours you got two replies
So what do you think mate?
What does that tell you?
We are behind you man quite a lot of us
We are watching your progress with interest
Keep at it
Cheers

[opcode66]

Thank you mossboss!

[mossboss]

Hey Opcode
You are most welcome
Cheers

[gold]

Your approach seems to be trying to build a better mouse trap before you know why the mousetrap was built the way it was, and if it needs improvement. I suggested early on in the thread that you try to reverse engineer the Zuma. This will not be easy and it will teach you a lot. I myself can't do this so I can't be of much help. I thought it was a constructive suggestion.

You have to learn how the basic concepts work for yourself. This is a mixture of theoretical and practical knowledge. No one can do this for you. You have been talking about how you are going to make a great computer with modern parts and improve the working of the VMS70. Maybe I missed the questions you asked.

I gave you good hints in the last posts directly related to figuring out the technical requirements of the AD and computing power. I was both pointing out what you don't know and leading you in the direction to find out.

Pointing out flaws in your approach is not 'putting you down'. But there is no way like the hard way...

[opcode66]

I am looking to make something better than the stock VMS70 pitch computer. I am not necessary looking to make something better than the Zuma or Vinylium Pitch computer. But at least comparable. The only advatages would be using modern chips and so I can offer modern conveniences with respect to flash updates and 24 bit audio processing.

Also, I want to make something cheap and affordable. I might even make the design open source and post it.

I do understand the concepts of pitch/depth control. If you look at some of my posts on other threads here I think you will see that I understand the concept. I do need to figure out some specifics, but all in good time...

I feel as though I am well on my way to a good start. Maybe not... I certainly respect your experience/knowledge/opinions Mr. Gold.

[gold]

The only advatages would be using modern chips and so I can offer modern conveniences with respect to flash updates and 24 bit audio processing.

Okay, I'll spell it out. A 24 bit converter has a dynamic range of 144dB. On a great day vinyl has a dynamic range of about 65dB. In practical terms I'd say it's more like 40dB. So your 10 bit converter has all the dynamic range necessary.

I'm not trying to be discouraging. I'm sure you are capable of doing it. I'm just trying to reorient the position of the cart and the horse. And I generally go by Paul.

[opcode66]

From past experience ive found the higher bit rate adc's to be more accurate and more reliable. Just seem to bd made to more exacting standards. That's the reasoning for stepping it up. I am doing adc right now with good results with the 10 bit converter on the 16f887.

[mossboss]

OK Opcode
This thread has had around 1000 views Now by comparisson to other threads it has a lot of interest Now any technical input good or bad has been provided by experienced cutters But let me say this there are a lot of others following this thread closely and chewing over whats been posted here
Youd be surprised, when all the arguments have been settled one way or another you will see further input from a few more who may just be waiting for the dust to settle
Quite a bit of input already as Paul has done in his last couple of post's
I am sorry I am not in a position to give you any digital stuff I am stuck in days paaaaast
So you keep at it will happen because its worthwhile
I am not sure if this makes sense but there are more users here of archaic gear than pro's on "modern" cutting lathes If having made 30 odd years ago still modern
So if your proposed mouse trap can do the tricks for some of the Scullys or and the Prestos at least you would pleaseantly surprised at the response
It is my view that as the discussion so far has been centered around the VMS these guys are holding back So may we have your thoughts on this please If it is positive you will open a stream of input as there are some pretty smart cookies here who do a great job on these old dear machines
I am sure we will get to see the mouse trap even if it is restricted to VMS's
cheers

[gold]

Double post

[mossboss]

Gold, Aright, Frugal NY post's, Thomas, Dietrich, You, Me? Positive. C

[opcode66]

The value reads 1023 when there is no signal. When there is signal, the value goes down from 1023. I can reverse that so the value starts at zero and goes up when there is signal. I'll get to it later...

http://www.youtube.com/watch?v=VegUN2NuclE

FYI, the audio is a recording of me performing a Live PA. And, yes, that is a real Roland TB-303 you hear and not a clone or VST plugin.

[Simon]

It is a great project and you need to crack on with it.

Would it not be great to have something that you could attach or modify for different lathes.

[opcode66]

Working on the audio input circuit to balance and amp the input signal properly. Using the Zuma schamtics as a guide.

Going to spend some more time on code this week. Want to get sensing of two signal simultaneously done. Also want to write code to perform the following steps every 1.8 seconds (one rev at 33.3):

1. Clear all samples for left and right channel.
2. Monitor the input audio. Store and display the highest value withing the first .45 seconds.
3. Do same as step 2 for following 3 quarter segments.
4. Repeat steps 1 -3.

Once that is done then I can move forward with interpreting the values and generating the proper output voltages via PWM and a rc circtui.

Finally I add code to sense the status signals from the lathe.


Keep you all posted.

Opcode66

[mossboss]

Hey Opcode
I am following all this with great interest But my own exposure to digital music is one big fat ZERO I am getting the drift of it but I am afraid you will get no input from me on the fine points of it
All I would like to see is the ability to set a minimum depth of cut without any of the input whatever it is interfering with it
Than the bigest bugbear of a dissapearing groove due to an out of phase signal would be dealt a death blow never to bother us again with the added benefit that the music is not interfered with
Cut as submitted
That would be the answer to all my prayers as it is the only thing that concerns me most
Cooking the head my other concern can be dealt with We allways cut at 0 ref may be if the materiaal allows we give it an extra dB so it is not a real big issue
Having a cut that you missed some out of phase bits and loosing your groove is a pain
By the way Deliberate static introduced into the music as some doom metal stuff seems to have an uncanny ability to by-pass all safety precautions already on the VMS 70, SAL 74 B rack with all the extras in it
My own experience has been a bad one since it cooked around 26 MJ output trannies on the main amp output cards for no apparent reason
The head temp indicator was less than 60 C way bellow the 200 C that Neumann suggest for the 74 head, cutting level on this album was at +1 dB bass was monoed and split
It was loaded and cut after a good look at the freq analyzer it seemd to be OK Well it send the whole system into a high frequency overdrive
Real weird so after replacing all the cooked trannies anything above 16 k was cut but that was after the damage was done
So may be that is something that you may want to look into as well since you are taking the input chain right from the start
Since the feedback gets rolled off at around 14 khz from the head and we have that set as such (there is a jumper setting on the boards for this) and since the 74 has a mechanical reasonance at 22khz a complete cut off of anyhing above say 20 K would be a very good safety measure
A choice in the range of 14K to the 20K range for the cutter to decide what he wants through would certainly be a worthwhile addition
I can hear/see the onslaught on this request comming However Yan De had something worthwhile to say in his post "The Music" and that is the whole point
In my view lets protect our gear but lets do it doing justice to whatever was submitted by the artist
We are not to pass judgment or interfere with what has been given to cut as original material, we should stay within acceptable parameters given the limitations of the medium that is for sure but we should really leave well mastered music alone as it was already approved by the client
To often we see post's here of what can and cannot be done cutting levels as well as all sort of request's by cutting guys that to me make no sense
A mastering guy well versed with the industry standard VMS would already have taken all the necessary steps so as to provide material ready for the lathe
The issue becomes cloudy when the "bedroom" mixes as well as the plethora of "Plug In's" are used to provide the end result
One look at the analyzer screen tells you that there are things lurking there that you just have no idea what they will do therefore the request
Sure there is enough gear on the input chain to allow one to do that any way but you have either a wholesale cut interfere with what has been submitted or take a risk with certain stuff
What I am suggesting is:
Avoid wholesale cuts prevent damage to the head/Gear
By the way
There is a post on the net by Stan Ricker where he suggests that the SX 74 with some fancy amps built by a coloborator of his is capable of cutting at 120 odd Khz!!!!
The head picked up the AC bias of some music recorded on tape which was visible on the lacquer
Kevin Gray confirmed in a post here that he has seen that himself I have never seen it myself
If you think about it it seems reasonable that a clean well generated AC signal as used on tape deck bias circuitry would get through the chain given that the amplifiers are good enough to reproduce it
It is most likely in its fundamental frequency as it certainly would not be seen at its second or third order
4 track quad records used a similar technique with coders and decoder so as extract the info out of the other two channels out of the cut
Be that as it may I doubt very much I want to see it on a lacquer that is cut on a lathe I own
Since you have now made a very substantial investment on your VMS it would certainly be to your benefit and advantage as well to do something along the lines suggested
I am sure others would also have some input on this as well
There are quite a few cutters here that have cooked heads in their first few months of cutting
Most of the time they never really have a clear understanding why the head was cooked
Most say they drove it to hard but I have my doubts about that it is most likely high freq stuff that sends it ballistic
If it was just straight out high cutting levels the protection already inherent on the VMS rack would prevent any damage to it
They just fork out a few $k and get it rewound and keep on cutting
An expensive escersise indeed one to be avoided at all cost's
Ok now lets see what comes out of this

Cheers

[Steve E.]

I have been missing this thread, because it is in the wrong location. I am going to move it to the top forum.

--Steve (Admin)

[flozki]

to mossboss:
"My own experience has been a bad one since it cooked around 26 MJ output trannies..."

welcome to the 2nd life of your sal-rack. with growing age it starts to oscillate on a few MHz.

most people destroy their heads because they buy a $20k-30k equipment which is 30 or more years old and think they can use it just as it is new..

neumann sal74 amps are close to hf transmitters. because of their construction 6 cards per amp. long cards. approx. 200 connectors from input to the drivecoils....a highenders nightmare.
you dont see that on the current meter. and often it is too fast even for your circuit breaker. as a consequence you blow your headcoils. or the output trannies or both..

so i can just say once more:
spending 2-3k on someone who knows to fix the stuff (unfortunately there arent too many out there who really know how to fix and not just talk and ask big money....) would prevent blowing heads.and output transistors. and much more.
its even cheaper than fixing heads. after 30 years a big service is more than necessary. and it is not only the caps....
or just buy a new set of amps...

[mossboss]

Hey Flo
Thanks man I know exactly what you are talking about I agree with you 100%
Now having said that why is it not possible for a reasonable technician to be able to look after this beast
Sure as you said it is not only caps you are right By the way the highest quality caps we could get still measured leakage more than the ones already there even after 30 years
So after removing them and checking them out both passively as well as under power we just put them back again
To be honest the lathe has been extremelly reliable so far and without that incident that got me by surprise we had no more than a few relays that switch from the console to the main rack gone not quite gone bad just bad contacts
I have sufficient spares to keep it going for a while yet It is not a complex system to fix things on so long you know what you are doing that is
Now having cut around the 8 thousand odd sides plus the rejects for whatever reason that would add another say 500 as well as a heap of dub plates and having a hick up through our own stupidity does not call for a major rethink of lathe maintenance in my view
Sure it will break into oscilation just like you describe but its got to have a damn good reason to do so and guess what we gave it to it That's all
We have a UPS with a stack of batteries from the power supply to the lathe all components including the console as well as all other auxillary equipment are supplied from the UPS
The ups is a doubled up one 240 V in down to 12 V dc storage on sealed lead acid accumulators Out at 12 V dc to the inverer and back up to 240 AC Wave is a litle off but so what it gets converted back to the required voltages
This way any glitzes as well as any stray currents as well as brown outs or spikes including any HF stuff that may be injected by large capacity VFR's elswhwere are held away from the lathe being sunk in the first conversion of the 240V to 12 V dc
Nothing gets through the batteries regardless any way
Everything is grounded even if the gear is double insulated we will run an earth to a common point including any metal stands around the lathe
So unless some dude stands out side our cutting room with around 3 KW of RF coming out of his CB at around the 27 MHZ and something on the lathe picks it up when it is turned on the likelyhood of it breaking into oscilation is very remote indeed
Now why do I do all these things It is exactly what you said This thing is just one big hf transmitter and being an ex amature radio operator I know one when I see one Flo
May be this post of yours as well as my reply will help others following this thread
There is a funny twist in all this When the output trannies went down I checked out my spares box My stock of MJ was around the 6 units I breathed a sigh of releif thinking it will be one or two Well when the real situation was established panic set in
On to the net and start looking for Motorola manufactured units around the 1970-75 era Plenty in stock all around the world but not the right dates and expensive as well besides the time delay
So I remembered an outlet up the road that deal in surplus components One phone call and guess what they had 52 in stock the right dates as well as made by Motorola So I asked them how much money do they want for the lot the amswer was You can have the lot for $50 mate They have been there for 30 years No one wants them any more
I think I broke the speed limit more than once getting there just in case they went or he changed his mind
So we matched them up replaced all of them on any card that had any fallen soldiers ie, the dead ones and back in buisiness, Relief
Sometimes ones stupidity is rewarded with a bit of good luck just to ballance it out
Well, May be, I would not try that again that is for sure
Cheers