The Secret Society of Lathe Trolls

Thanks for posting that. It was interesting. It sounded to me like the second recording started off very similar to the first and then the highs dropped out slowly. Maybe the damping heated up and changed its properties??

Mark

Hi Steve, That seems odd to me. Most moving iron heads have much higher main resonances. For example, the Presto 1C/D is up in the 4Khz range IIRC. I don't know the RCA heads well, but I wonder if it has lost its stiffness due to an incorrect mechanical adjustment or maybe metal fatigue?? How is the...

Hi,

You might get a better response if you indicate where you are located and what types of tubes you have to offer. Are they audio types like 6L6, EL34, 12AX7, KT88, etc.? Or, are they random TV and radio tubes.

Regards,

Mark

Hi Estacaco, 8 ohm is fine as long as you have an amp that can drive enough power into the head. The driver can only handle about 3 watts on a continuous basis. But, to cut a decent levels you could need 50-100 watts for short duration peaks to cut the high frequencies. When using an amp with that m...

Hi, The screws don't need to be very long. I only had 1/8" long 2-56 setscrews here and they worked fine. Once you get them so they just protrude from the surface, you are not moving them much higher. One turn is probably quite a bit of adjustment. A small change in height at the center of the platt...

Hi Everyone, I have an update to my 7" platter mod. One of the big issues was getting the platter to run true. I tried various solutions involving some sort of post processing to the 3D print to get the top face of the platter to run without up and down run out. Some methods worked ok, but are not v...

Hi,

Here is a link to a post I made several years ago that may help.

https://www.lathetrolls.com/viewtopic.php?f=1&t=8561&p=54602&hilit=LM317#p54602

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...