My homemade stereo embosser

[Blazin Studios]

Hello trolls,
I started my journey in January by browsing YT and other sources about creating records. I came across Davids video (Pentlandsound) and that really got me started in February. I do have some experience in audio electronics and simple mechanics so what could possibly go wrong….. I built my fist lathe on a linear rail I got through the Dutch ebay, not even knowing how to power a stepper motor… My goal was to build something “as analogue as possible” so I chose to power a 8825 stepper driver with a small NE555 set up. This worked rather well actually so it was time to build a stereohead, some audio electronics and a stylus. The preamp I built more or less follows the inverted RIAA curve. At first the stylus clamp was mounted in soft rubber to allow easy movement…. But after some testing I realized this rather moves the clamp than the stylus and even rotated the clamp a bit as to swing the stylus in the x- direction. So I made very scratchy trials, even with a heated stylus. I used weights between 30 and 80 grams, exciters in and out of phase, stylus angles of 90-75 degrees, polycarbonate temperatures between roomtemp and 50 deg C….. WD40, and results were still meager. The frequency spectrum was limited to 5 kHz. Sometime in March I found this forum and read a lot about the details involved (thanks Thomas, the farmer and his plow). So, after making a lot of mistakes and learning about the differences between cutting and embossing, steel and tungsten, looking through the microscope trying to understand what was wrong I came up with a new design which allows the correct stylus movement, and limits the unwanted movements (still without the famous V-spring). The head is made from plywood, and the clamp is aluminium. The coil exciters (5 Watt) are connected through tin beer can cones and a small steel rod to make the connection to the stylus clamp (torque tube). Here is a picture of my rudimentary embossing head:

[Blazin Studios]

To review the stylus movement in detail I made a macro video in slow motion by filming at 25 fps, lighting with a strobe light at 300 Hz, and powering the exciters with 295 Hz at 3Volts. The stylus is tungsten 1,6mm. Here is the video:

[Blazin Studios]

Although a lot of tweaking is still required the results with the new head are actually promising and the stereo effect is not too bad - although not like the original input. When testing with tones and white noise I measured results up to 19kHz (max 20dB above noise floor). Here are two music sound files embossed at 33 1/3 rpm, room temp polycarbonate, stylus at 85 degrees angle, 38 grams. The core 2 (Eric Clapton) has a nice silent groove, whereas The core 3 is rather noisy (no WD40) and has lower volume. In both cases the balance slider has been moved to L, then to R, and back to center, at some point during the recording. At the beginning of The core 3 you can hear the stepper slowing down because this recording is the first one on a new blank. The wider starting groove progression of 1mm/rev needed to slow down to my current normal progression of 130 mu/rev.

So, this is where we are today. Still a lot to do! Any comments or tips would be appreciated!

Greetings from the Netherlands,
Tom

[kugelblitz]

Nice results! Can you post a picture of the rest of your lathe as well?

[Blazin Studios]

Thanks!
Pictures of the setup are below.
The white plastic icecreambox contains the stepper driver and the pulse generator. The switches are for 1. start stepping, 2. direction, 3. switch from 1/32 to 1/4 step. The groove advancement is regulated by the potentiometer that defines the pulse frequency to the stepper driver.

Tom

[farmersplow]

What looks so simple can be so difficult. You have built a cutter with simple means and with a not so bad sound! I congratulate you and hope you continue to uncover more secrets of the lathe. If you have questions, there are many in this forum who can help you with one or another suggestion.
The video with the stylus (Left-Right Center) I find great!
Keep up the good work and greetings from Austria
Thomas

[Blazin Studios]

Thanks Thomas, let's keep on plowing!
Tom

[jjwharris]

To review the stylus movement in detail I made a macro video in slow motion by filming at 25 fps, lighting with a strobe light at 300 Hz, and powering the exciters with 295 Hz at 3Volts. The stylus is tungsten 1,6mm. Here is the video:

This is such a great video! Amazing method/process to capture the movement too!

It's hard to describe the 45/45 movement but this video does it so quickly.

[Groovecutter]

what did you use to make the cutter head move up and down connecting to the lead screw?

[Blazin Studios]

I use 2 ball bearings to pivot the head. There's a stainless steel rod connecting the bearings to the frame. The frame is bolted to the linear rail. See pictures.

[Blazin Studios]

Hi trolls,
It took some time due to other projects, but I finally got to explore one of my ideas to implement a de-esser. Since I want to make my embosser as analogue as possible, the idea was to take one of my old cassette decks and put the Dolby system to use. While in record-mode the Dolby compresses the higher frequencies, hence limits the extreme peaks in the esses. So I found my 1973 Akai deck, opened it up and searched for the Dolby output to the recording circuit. I evaluated the output with white noise in the spectrum analyser and found out that the best results were obtained when peaks were at -10dB on the decks VU. Higher freqs are boosted now so I had to adjust the EQ accordingly. The system works, but I still have to find the sweet spot…. Next phases are optimization, and working on the stepper rumble….
Pictures of the deck are attached, as well as links to my youtube channel where I uploaded 2 playbacks (when headphones are used the stereo can be heard beautifully).
Greetings from the Netherlands,
Tom

[JoelSD]

Hey Tom,

Congratulations! That's sound great. What exciters do you use in your cutterhead?

Best regards
Joel

[Blazin Studios]

Hi Joel, I use Dayton Audio's 19 mm DAEX19CT-4 coin type exciter.
Regards, Tom