I am running multiple VRs and wanting to get things running a little tighter across them collectively. I map each of my cutter heads and use my own iRIAA curves to bring them all together soundwise, but now want to replace the main unit (i do not use the EQ, just heat and pitch) and wondering if anyone has any tips for a simple solution for both diamond heat and pitch, with a digital read out for more accuracy.
Thanks!
Replace main unit power for heat and pitch
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Re: Replace main unit power for heat and pitch
Hi,
I don't own a VR, but I did work on and repair the pitch section of that unit for a friend.
IIRC, the pitch control was just an LM317 adjustable regulator circuit with a provision made to allow the voltage to be adjusted via a pot and/or via an external voltage control. At first glance, you might consider that a single central adjustable power supply bussed to all of your lathes would give you tight control. However, the pitch motor is run open loop and so I would not expect that each lathe would require the same voltage to obtain the same pitch. The same is true for a typical stylus heating system. Each stylus will likely need its own adjustable supply to dial in the correct heating. You could easily roll your own central power supply that has two adjustments for each lathe, but I suspect that would not be very convenient since you probably want to be at each lathe location to make the adjustments. I could be wrong here, so take what I way with a grain of salt. Hope you find this helpful.
Mark
I don't own a VR, but I did work on and repair the pitch section of that unit for a friend.
IIRC, the pitch control was just an LM317 adjustable regulator circuit with a provision made to allow the voltage to be adjusted via a pot and/or via an external voltage control. At first glance, you might consider that a single central adjustable power supply bussed to all of your lathes would give you tight control. However, the pitch motor is run open loop and so I would not expect that each lathe would require the same voltage to obtain the same pitch. The same is true for a typical stylus heating system. Each stylus will likely need its own adjustable supply to dial in the correct heating. You could easily roll your own central power supply that has two adjustments for each lathe, but I suspect that would not be very convenient since you probably want to be at each lathe location to make the adjustments. I could be wrong here, so take what I way with a grain of salt. Hope you find this helpful.
Mark
Re: Replace main unit power for heat and pitch
Hi Mark!
I worded this badly. I want a control for each lathe, separately, i just want a digital read out so that i can get them accurate, rather than the knobs and stickers. So i will be building a separate unit for each lathe.
I worded this badly. I want a control for each lathe, separately, i just want a digital read out so that i can get them accurate, rather than the knobs and stickers. So i will be building a separate unit for each lathe.
Re: Replace main unit power for heat and pitch
I should add, the main issue is pitch. I cut a lot of records, about 300 or 400 a month and when calibrating for a run it would be ideal if I could dial in the pitch so that the same voltage is easily achievable to each lathe. Currently my 3 main units are all totally different and it’s purely just to save time, getting each unit replaced with something more precise. If doing this I might as well do the diamond heat too and replace the full unit
Re: Replace main unit power for heat and pitch
Hi,
I see. A couple of options for you:
1. Add a digital panel meter to the exiting VR box to allow you to read the motor voltage digitally. My concern with this approach is that the repeatability might be poor. The voltage will be very repeatable, but the actual motor speed will probably not be (especially at higher LPI settings). You would have to run some tests to qualify things. I also would not expect setting to the same motor voltage on each lathe would yield the same LPI.
2. Measure the actual pitch motor RPM with an optical tach. I don't know what RPM the pitch motor runs at for your target LPI on a VR. I suspect its pretty low. There are low cost optical tach's available from around $20 that read down to 2 RPM. At that low RPM, the resolution suffers to the point that it may not be accurate enough.
https://www.amazon.com/Digital-Photo-Laser-Tachometer-Contact/dp/B001N4QY66
You could increase the RPM reading (and resolution) by adding multiple reflective tape dots around sensing shaft. Sensing the shaft RPM would directly relate to LPI and would be very repeatable. If you have some hardware chops, you could coble an optical tach using an Arduino with a display and have it scale the tach pulses to LPI for direct readout. The best approach would be to add an optical encoder (200 pules per rev or higher) to the pitch shaft. But you get the idea.
Mark
I see. A couple of options for you:
1. Add a digital panel meter to the exiting VR box to allow you to read the motor voltage digitally. My concern with this approach is that the repeatability might be poor. The voltage will be very repeatable, but the actual motor speed will probably not be (especially at higher LPI settings). You would have to run some tests to qualify things. I also would not expect setting to the same motor voltage on each lathe would yield the same LPI.
2. Measure the actual pitch motor RPM with an optical tach. I don't know what RPM the pitch motor runs at for your target LPI on a VR. I suspect its pretty low. There are low cost optical tach's available from around $20 that read down to 2 RPM. At that low RPM, the resolution suffers to the point that it may not be accurate enough.
https://www.amazon.com/Digital-Photo-Laser-Tachometer-Contact/dp/B001N4QY66
You could increase the RPM reading (and resolution) by adding multiple reflective tape dots around sensing shaft. Sensing the shaft RPM would directly relate to LPI and would be very repeatable. If you have some hardware chops, you could coble an optical tach using an Arduino with a display and have it scale the tach pulses to LPI for direct readout. The best approach would be to add an optical encoder (200 pules per rev or higher) to the pitch shaft. But you get the idea.
Mark
Re: Replace main unit power for heat and pitch
Thinking of a VR version of how Doug Sax famously 'entrained' the carriages of multiple lathes so that multiple masters or a master with identical refs could be cut simultaneously. Although his lathes were not the 'overhead' / Lyrec type - rather, the Neumann type with leadscrew driving a wheeled carriage, whereas the VR looks like an 'overhead' type with the elevated leadscrew driving the saddle, directly, yes?... But what if the leadscrews of the additional VRs in your room didn't have their threads but instead were smooth and lubed and the saddle of the master VR was physically connected somehow to pull the slave saddles of the other VRs along with it, across their respective, smooth lead-bars? Is that feasible? The electrical signal for the master VR's depth coil (if appl.) could possibly be multed to the slave VRs' depth coils... That's what the Sax machine did from the Sontec Compudisk, innit?
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trailerparkjesus
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Re: Replace main unit power for heat and pitch
Following this thread... I am also interested in this