So I’m thinking about a new project to work on, and I’ve got a fairly ambitious idea: Build A Drum Sequencer

After looking around and talking with via some forums, I’ve come to realize that there really is a lack of any sort of stand-alone step sequencer for use with drums, especially in kit form.

Thinking about it, I believe that I could probably take the digital part of the x0xb0x, add or remove LEDs and buttons as needed, then rework about half of the software so it works a bit differently. Using a few resistor networks I think I could simplify the panel a bit too…

So, I think there’s a couple of (major) steps to doing this. Then I could even sell the thing in kit form. Those steps are:

· Settle on a feature set and the buttons and LEDs this will require.
· Rework the x0xb0x schematic to reflect this.
· Design a panel layout which will be usable, fit a readily available enclosure, and will allow the parts to fit around each other on the PCB.
· Order some sample PCBs and build a prototype.
· Rework the x0xb0x software to do what is needed.
· Look into selling either PCB sets w/ parts lists or full kits.

I wonder if this is within my abilities.

I think as a test I may to write some new x0xb0x software which will sort of implement this functionality, just to see if I can manage that part…

Tonight I got the modifications to my PAiA FatMan all implemented. Unfortunately, after powering it back up I realized that it wasn’t quite working any more.

When I press a key, I’m getting a single shot of sound for each key press, in a way which almost sounds to be as if the synth is generating a single wave and then stopping. Both VCOs are doing this.

The VCF still seems fine as does the VCA, and I’ve triple-checked everything. I even went so far as to individually remove all the lines which actually implement the various modifications in order to rule them out.

My current thought is that when attaching the wires to the back of the PCB I fried both of the new CMOS 555’s which I put in. My thinking is that non-functional timer, things can’t repeat, etc… It’s also the only thing I’ve touched since I had it working last night.

I’m fairly confidant that all the digital stuff on the board is still good, all the way through the midi -> cv part of it. The MIDI light blinks, the gate LED goes solid whenever a key is held down. Also, the VCF and VCA change the sound appropriately when one fiddles with the knobs. If I crank the release on the VCF way up, a sustained sound is heard. Even the modifications I made seem to be working, just for a very brief period of time.

Fortunately I had ordered four 555’s (originally only used two) and I’ve got some DIP8 sockets laying around, so tomorrow I’ll just replace them with socketed parts. I’ll also do one, test, then go from there…

I really, really hope that is the problem. I’d love to hear ideas if any of you think it could be something else. The schematic can be found near the end of this PDF.

However, the only points I did anything with on the board since it was working last night are the 555s, part of the VCF to provide audio in (soldered to a pin of an IC), and half of a resistor, so the 555s will be the first to be swapped tomorrow.

Oh, and it sounds really, really cool with these modifications. Much improved over the original.

UPDATE: Gur. I’m an idiot. Of course you’ll just get a burst of sound with ‘sustain’ in the VCF turned all the way down. Guh. Yeah, it’s working fine… I just need a new EPROM with new software on it to work around the FATMOP v1.8 (or whatever) MIDI bug.

After another night of working on synths, I have something to show for it. Tonight I got the PAiA FatMan I am rebuilding (photo gallery retired) working, and as a test I had my x0xb0x triggering it, and both of their audio mixed together.

Listen here: http://www.nuxx.net/files/x0xb0x_and_fatman.mp3

Also, flying wires to a front panel are a pain in the ass. Photos later of why.

Error in my x0xb0x Panel Overlays

Well, this is good. I’ve been in touch with MaverickLabels.com about the error in the printing of the x0xb0x panel overlays. I’ve been told that the reprinted panels will either ship today or tomorrow. This makes me quite happy, because hopefully I’ll have the synth finished by the end of the week. So, while there was a problem with the printing, that company is definitely doing a great job getting it sorted out. I feel a lot better about this all now.

Now, just two more synths to finish… Well, that’s before the 9090 project (and this will be a HUGE project) begins. More on these other two later.

[This is a cross-post from here in the ladyada.net Forums, redone in HTML instead of BBCode.]

Well, that should whet people’s appetites.

That photo above means that I’ve received the panels from MaverickLabels.com. There are both good and bad things about this…

First, the good:

– The panels look excellent. The colors are exactly what I wanted, and the print quality is outstanding.
– Everything appears to align nicely to my x0xb0x panel.

Now, the bad:

– See the image above? See how it is missing the lines from the bank indicator switch through hole to the numbers? They aren’t right.

This means that I’m not going to sell / ship them yet… MaverickLabels.com is closed until Monday, at which time I’ll be calling them and seeing what they will do to sort out the problem. I find it interesting that these lines are missing, as the digital proof which MaverickLabel.com sent has them in there.

I am hoping that they will sort out the problem and get corrected labels shipped to me quickly.

In the mean time, here’s a few more photos involving the finishing of my x0xb0x and the panel overlays:

– High res scan of one of the panel overlays I received tonight to show the detail of the printing and the error. (Please note that the colors aren’t accurate, and the sparkly appearance is because of the texture of the Lexan.)
– Stack of all 12 panels, not long after they were removed from the shipping package.
– The original proof sent by MaverickLabels.com.
– Glare-filled comparison of an x0xb0x panel overlay (with error) and the original x0xb0x panel.
– A smaller version of the scan of the panel, with the missing lines pointed out. This was made so I could send it to MaverickLabels.com.

So, that’s that. Everything is on hold until Monday when I can talk to the Customer Care people and see what they are going to do to sort out the problem. I don’t see a problem with things getting sorted out, especially if they are willing to put a guarantee like this on their site. But, we’ll see…

Per usual, I’ll keep posting updates here.

-Steve

The traces are nowhere near as clear as they should be.

So, yeah. Tonight I tried to make the printed circuit board detailed in this PDF on this page for making it possible to trigger my Casio SK-1 via MIDI.

Well, I learned two lessons in doing this…

First, my technique for registering the two sides on a double-sided PCB appears to be successful.

Second, my method of laser printing the mask on vellum and exposing to fluorescent light for 10 minutes isn’t good enough for fine lines. As you can see above, something went awry and the photo resist between the lines wasn’t exposed to enough light.

I think I’m going to try an experiment with various levels of detail and a smaller single-sided PCB with a piece of laser printer transparency, just to see how well this method will work. I don’t think it’ll work out so well, but it can’t hurt to try…

If this doesn’t work, I guess I’ll have to order some special paper just for doing this kind of thing. That won’t be cheap…

Well, at least I’ve got a few more unexposed boards to play with.

Hmm… Should I build a 9090?

In short, it is the synth portion of a TR-909, but without a sequencer…