The Secret Society of Lathe Trolls

Hi, Here's an idea for a quick way to implement one. I seem to recall that the VR has an input jack that takes a analog control voltage that modulates the groove pitch. If you buy an off the shelf MIDI to CV convertor used for analog synths and Euro Rack setups, you can setup a DAW to add a MIDI tra...

Hi, I would think a single impulse measurement would have a very low S/N ratio. If you average many impulses you can improve the S/N , but that's not so easy to do. I guess if you window out the single impulse to be very short in duration, you would effectively filter out all of the low frequency no...

Hi, I'm thinking that you could remove the magnet from the head so that the stylus no longer moves when a signal is fed to the drive coil. If you monitor the feedback signal with an analyzer while feeding the head, you will only see magnetic leakage pickup from the the drive coil. If you adjust the ...

Hi,

Congrats on the book and disk!

They don't write em like that anymore!

https://www.youtube.com/watch?v=Y3JVTBFgi1w

Mark

Wow! Thanks for posting!

Mark

Hi, The two driver heads are indeed typically stereo, but they can cut mono if you feed them a mono signal. They are in fact wired in reverse polarity so that if you feed them an identical signal on both drivers, you get a lateral cut mono groove cut. If you wired them with the same polarity, they w...

Hi,

Should be a good primer before you get into the big build. Let me know if you have any questions.

Mark

Hi, When I first listened to the link, I thought it was stereo as the clips and pops were left and right. The music is definitely mono. The quality was way better than you would have obtained from the built in speaker. I read down in the comments and saw that he replaced the original dead crystal pi...

Hi, Have you tried driving the stock head from a higher powered modern amp? You should be able to push the response a bit with more power. You still have to make sure you keep the average power low to keep from smoking the head, but moving to an high power amp and more drastic high frequency EQ than...

Hi Everyone,

This looks like some really big news in the one off lathe cut world:

https://www.youtube.com/watch?v=yV1egpbrg90

Mark

Hi,

Here is an Imperial II manual. Hope that helps.

Mark

Hi, If you get it to null out the drive coil over the entire frequency range and are able to prove that it is really picking up the armature motion like in the video, you will need to run an open loop frequency and phase plot to determine if you can just sum it or if you will need some form of loop ...

Hi, The 2208 and 2209 are very similar. There are some differences, but if the 2208 works for you, I would not change to the 2209. Here is a nice rundown of the differences. https://www.utmel.com/components/tmc2208-vs-tmc2209-what-differences-is-between-them?id=1378 Here is my spread sheet with valu...

Hi, You should be able to get a handle on the required torque if you attach a lever off of the feed screw shaft so its parallel to the surface of the table. Hang weights off of the end end of the lever see how much it takes to break free. Measure the length of the lever and the torque is the weight ...

Hi,

Very cool idea. Eddie Celetti is a legendary audio tech guy. I like they way he is testing to make sure he is picking up the motion of the stylus rather than the drive current into the coil.

Mark

Hi, AC or DC should not matter for a heater. As far as voltage goes, I'd measure the coil resistance and bring it up on a Variac slowly to see if that is really a heater an if the switch is a thermostat. You could also try heating the "thermostat" with a heat gun or hair dryer and monitor the contac...

Hi,

I'm wondering if it is a heater and thermostat combination to keep the damping material at a constant durometer so that is better controls the resonance of the head. Just a guess.

Mark

Hi,

Next time you have things apart, post a picture. There may well be a difference.

Mark

Hi, You might have a tolerance issue between the bottom white pulley and the platter. The shaft of the white pulley has a key slot that engages the platter. The metal center pin is also keyed and should be a bit shorter than the surface of the white pulley. When you add the keyed overhead pulley and...

Hi, The reason for cutting inside out was to make the transition from a multiple disc performance seamless for broadcast. If you start cutting inside, you have lower fidelity. As you move to the outer diameters, the fidelity improves. When you reach the end of the side, the next disc starts its reco...