The Secret Society of Lathe Trolls

Hi, Yes. I think you have the idea. I'm doing a bunch of hacking to the PO-80. I've updated the motor on mine with a small NEMA 14 stepper and Arduino based controller. Its not quite ready for prime time yet, but keep an eye out in the thread I've been posting to on this subject. I'm also looking to...

Hi,

Instead of removing material, you basically empress or indent a groove. Does that make sense?

Mark

Hi, I flip the stylus 180 degrees and emboss on CD-R blanks rather than cut. They stylus lasts quite long and the blanks are cheap. You will have to make a simple adaptor to reduce the center hole of the CD-R to the standard record hole diameter. I 3D print them. Here is an STL file I created that w...

Hi,

Thanks so much for posting this!

Mark

If you value your records, you won't try that. Also note that the RIAA curve you see published is for a typical modern magnetic pickup. If the Astatic is a crystal or ceramic, that curve does not apply. See the article below with some more info. ceramic_cart_1.jpg ceramic_cart_2.jpg ceramic_cart_3.j...

Hi, My thinking is that if you want to attract investment money, you need to cobble up the simplest proof of concept prototype be it playback or recording that can demonstrate the merits both technical and economic. Do the least amount of work required using off the shelf parts. Something even as si...

Hi,

Could this method be reversed to work as an optical pickup?

Mark

Hi,

I think that's right. I would assume if you measure the DC resistance at the terminals that connect to the head, it will be quite high as compared with the 8 and even 500 ohm taps.

Hi,

So it is a matching transformer. Do the two black wires go to the cutter head or the power amp output?

Mark

Hi,

Looks interesting. How would this approach create the groove geometry needed to be compatible with a standard phonograph record? Have you built up a prototype? Are you aware of the HDVinyl endeavor? The were not able to bring it to market despite a great deal of funding.

Mark

Hi,

Looks like a matching transformer. I can see what appears to be an 8 ohm tap and a common. Can't see the other terminal markings.

Hi, No need to experiment with the resistor. You are not trying to match impedances here. They added some external resistance to make the amp happy. 1.2 ohms is too low for this amp. This comes at the expense of wasting power in the resistor that could have been applied to the head. It would have be...

Hi, That makes sense. That would bring the load impedance up into a better range. The cap bridging the resistor will increase the high frequencies as it will bypass the resistor. The down side is that you are wasting quite a bit of power through the resistor (note the 5W rating). An external high wa...

Hi, I was looking at the datasheet on the STK011 and it seems to be rated at 6.5W into 8 ohms with a 24Vdc supply. I'm not sure if it can drive such a low impedance load. That was why I asked if there was a series resistor added to raise the impedance. The datasheet I found on line is not very good,...

Hi,

That DC Resistance is pretty low. I assume you measured the head out of circuit. Is this correct? I see that a STK011 amplifier is used in some of these machines. Can you determine if the head has any external series resistance added between the amp and the head?

Mark

Hi, All of the heads you see here are electromagnetic based. You are thinking of a moving magnet design vs a moving coil. Both are still electromagnetic. The places of the coil and magnet are reversed in the two designs. In the moving magnet style, you need a big enough magnet to be able to generate...

Hi, Looks like it uses a TPA3255 which can support the power they are claiming as long as you provide the proper external power supply. These class D amps are quite cheap now and it should work fine if the the design and build quality is sound. I'd give it a shot. Let us know how it works out for yo...

Hi, You will need a ton of high frequency boost to get the performance I was getting. Also, you should not use a full IRIAA curve in your signal path as this will kill the lows. Only some slight boost below 50 hz is needed as the head already has the required response from its resonance (about 800Hz...

Hi, See the attached photo. I first attach the ring to the driver. This acts as an adapter as the driver does not have any mounting holes. After the glue sets, attach this assembly to the frame. There is a gap in the frame to allow the driver terminals to be accessed. The driver ring should be flush...

Hi,

Did that rotatable 3D model I posted a link to not work or was it confusing or need more clarification?

Mark