New ADB Soundbox replacement

Started by barcher174, March 04, 2018, 01:46:41 AM

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Quote from: "Andreas"
Quote from: "barcher174"Either way, the video is probably not very useful anyway.

As far as i understood, this board makes it possible to power on a Turbo slab and use it with (Apple)? ADB keyb/mouse and VGA video - or not?
So i think the video-out is essential.

Yes, your understanding is correct. The problem is almost certainly with my cable. The Next original 19pin cable I have with no ADB connection displays fine. Rob is sending me one of the later cables with ADB to verify.


I received a proper cable from Rob today:

Part number: 4535.00

I had forgotten that even with B&W, the ADB connection makes the monitor run at a weird 72.5hz which my LCD can process, but not well. Trying another monitor I get a crystal clear image.

So the good news is that everything is working as expected now.

On the non-ADB front, I received parts this week to start a prototype. Based on what I've learned in the past week I'm feeling pretty confident that we can replace the soundbox entirely.

My plan is to use a rasperry pi to prove the communication protocol. While it's weird to use a computer to boot a computer, we can look into replacing it with a more compact solution after we have proof of concept.


Any plans on making the project files or gerbers available?  Just picked up a Mono Turbo without a monitor and looking for a cheap way to get it up and going.


I've still been working on this in my spare time. I put a socket for the custom ASIC which is found in both the first revision megapixels and all B&W laser printers. The board can now optionally do nonADB when this chip is installed, otherwise it does just ADB. Eventually I hope to replace the ASIC with my own implementation.

I made a few mistakes which I've corrected on the bottom (I rushed to get it done to coincide with some time off. Never rush it...), so I plan of doing one more spin.  

The drakenware solution looks much further along than mine (hopefully almost done?) so I don't feel any pressure to finish quickly. I'm going to keep working on this just for the fun of it.


Good job! The online port solution is certainly more practical than the previous revision of the board.
With the ports aligned on one side, it will be easier to find a suitable case for this board, or print a 3D replica of the original SoundBox case.


great project -  Congrats!
I would like to buy one if still available.
Best regards



Wow, what a great project.  Perfect for those who who just want to play around with a slab.  Are these boards going to be available for sale?
would love to play around with one. :)



I sent a batch to Rob at blackhole and I believe they are currently still available for sale.


I figured out how to pass the sound test using the NeXT ASIC. The ASIC requires a 8.4672MHz clock signal applied to pin 5 to verify the sound circuit is complete. I made a simple clock circuit to test:

For anyone interested I'm collecting pinout information here:


First sound output test:

The missing input clock was the key to getting it working. Now I need to work on cleaning up the output.

Rob Blessin Black Hole

Amazing this is a game changer  for legacy NeXT hardware.
Rob Blessin President computerpowwow ebay  [email protected]
303-741-9998 Serving the NeXT Community  since 2/9/93


Will this board fit into a Soundbox replica ?


The current board is the same length as the next soundboard, so it would fit with port modifications. I will try to keep the same board dimensions with sound.

Rob Blessin Black Hole

Hello Brian: Do you have Sound, Music and Signal Processing on a NeXT Computer Concepts and Reference manuals... if you don't I have both and would donate a set to you for the project as they have a lot of useful information of what goes on behind the scene with the software.  For both recording and playback :)
Does that sound chip have an amp or will it be possible to go out to powered speakers.
What about for recording a sound is that a whole new can of worms? I know the original sound card just had a powered microphone plugin where that later 4000A had a microphone attached.

 Best regards Rob Blessin
Rob Blessin President computerpowwow ebay  [email protected]
303-741-9998 Serving the NeXT Community  since 2/9/93


Hi Rob,

Yes, I already have a copy. I am going to use an off the shelf audio amplifier circuit. In this way you can plug in whatever output configuration you want. I have tested with both an original Mono amp and speaker as well as a stereo output to powered speakers. Audio in is another beast entirely. It's certainly a possibility, but honestly not high on my list of features, because I'm not sure anyone would really use it outside of a moment of curiosity. After another board revision I will probably shelf this for a while and get back to the DSP module.