Friday, November 21, 2008

x0xb0x SS#01. Component Log

All components in bold are considered important to optimize the x0x.

2SA733P hFE ratings
  • q8: 225
  • q9: 220
  • q10: 218
  • q27: 198

x0xb0x SS#01: Day 2. VCO

Since the PSU went relatively quickly, I went ahead and started on the VCO as well. Overall this was a much bigger task. While I'm not entirely new to electronics, I also don't have expert ... or even real intermediate skills doing this. A good chunk of my time in this phase involved troubleshooting, trying to get my homemade probe to work with the software scope (unsuccessfully), and trying to follow the steps and instructions really carefully. Total time spent was about 10 hours, four of which involved the above. I also socketed all the ICs and 'rare parts' and made my own cabling as per subatomic's x0xl0g. That also added to my overall time.

Because the scope never did fully work, I had to go the headphone route to test the VCOs. Again - a bit more time was spent on that. Thankfully I got to hear a saw wave before calling it quits for the night. I was quite thankful for that :) I slept better for sure! One unfortunate aspect in this is that the 2SA733Ps I have are all really low hFE. The highest ones I have are 225 so q8 has one of them in there now. I'll certainly be replacing these. It'll be interesting to hear what such low hFE will sound like though. So just as a note:

  • q8: 225 hFE
  • q27: 198 hFE

Day 2 was spent troubleshooting some more and filling out the rest (i.e. majority) of the VCO section. I continued to use the headphones as my 'scope' but I don't entirely trust the results. It really would be nice to see it on the scope just to be sure it's working as it should and that the frequencies are set just so. My multimeter and variable PSU have been quite good but I will need to get the scope up and running to really get the results I want.

One thing that baffled me was that the instructions for the VCO section are also not entirely complete. I had to double check the last round of resistors, caps, and ICs that would have to be added. I learned that I've been relying too heavily on the images at the site. I was a good exercise to have to track things down on my own and place the components correctly. These first two section taught me to have a clearer strategy before embarking on upcoming sections. I can see where I can be more efficient in this process.

All in all it was really nice to hear both the square and saw running. They're tuned quite well so far. Once the scope is up and running I can fine tune them some more.

x0xb0x SS#01: Day 1. Power Supply

I finally had a chance to get things started yesterday. Pulling parts on a per-section basis has been a little more finicky than I had hoped. I may still go ahead and sort sections after all.

Building the power supply unit wasn't too tough. I spend 4 hours building it. I have been working on it cautiously though so despite being a bit slower than I had originally thought, the results have been quite satisfying. I was interrupted numerous times as well so having to walk away so much meant that I'd have to review where I stopped before picking up again.

All the tests outlined in the instructions went just fine. I was able to dial in the correct voltage without any fuss. I did omit the power switch at this stage but after doing so many tests with the VCO I'm just going to add it in before I start the next round. It really *is* a pain to keep pulling the jack out every time.

Tuesday, November 18, 2008

x0xb0x SS#01: Day 0. Parts & Sorting

Very, very excited! Today the last set of parts arrived.

It was among the more important shipments: all the resistors as well as sockets for all the rare parts and a few other bits. Futurlec had the best prices by far, where 1/4W metal film resistors were $0.02 a piece, sold in quantities of 10. I decided to make the purchase worth my while so I picked up enough resistors for three units. If I decide not to make three I can just sell a round to another x0x builder for a good price. I also picked up a power switch from them ($0.65) but I'm pretty disappointed by the quality. It feels loose, flimsy, and cheap. I'll keep it around for breadboard tests but it looks like a bit if a waste of $. I won't rule it out yet but I think a nicer quality switch is in order.

My first statement wasn't quite true. There is actually a very small handful of parts I need to have everything on hand. I still need the following:

  • 74HC126 Quad Buffer IC
  • all the screws, washers, and standoffs
  • IC Socket strips (which are ordered but being shipped direct, so there's a slight delay)
  • knobs
The IC was the one thing I missed. The error was nothing more than me passing over it in the xls sheet. A1 Parts, a shop that's relatively close to me, has it for $0.99 so I'm not too worried about it. They also have some knobs and switches so I may be able to fill those gaps there.

I'm pretty critical about the knobs. It irks me that there isn't a supplier for really cool options. Most are pretty standard black knobs with or without a cap, maybe a line. I'd like something much more unique but it just seems like no one wants to stock any of them. Manufacturers make 1000 or 5000 minimum runs so that's out. There has to be a good source out there. I'm still looking and am prepared to hold out until I find it. It obviously won't affect the x0x's ability to function.

I also now have flat LEDs in white, blue, and UV. They look really good. I just need to work out what the appropriate resistance will be for them. I'll get to that soon.

So - the big task today was to test all the resistor values and sort all the parts into general categories. (Done! and Done!). x0xlog has everything neatly sorted on sheets. I considered doing that but frankly all the parts are already labelled. I'm going to leave them as is and see how I do.
I did bag them into groups though:

  • Adafruit parts
  • Rare parts
  • Chips & ICs
  • Resistors
  • Capacitors
  • Sockets and connectors
  • Pots, trimmers, encoders, switches
  • LEDs and LED standoffs
  • Miscellaneaous parts: switch caps, wall wart, wires, etc.
Obviously it's a very general grouping structure. It all lands into a bag or box each so it's quite manageable thouhg. If it becomes tedious I'll group them the same way it was done on x0xl0g. That's certainly well organized. I can't argue with that.

So - without a further delay - it's time to start! I couldn't be more excited.

Sunday, October 26, 2008

x0xb0x SS#01: ii. Goals

I signed up to the x0x waiting list in April of this year. By my humble estimation it looks like I may not actually see an official kit until about one year from now, November 2009 (if at all!). If that actually does come around, I'll pay for an official kit for sure. For now though, my goal is to self-source this unit. I want it up and running for about Christmas time so I can gift it to myself :) I've done quite a bit of reading about the project already and have sourced some of the rare parts too. I have some ideas about how it should look so I'm going to go outside of the official Bill Of Materials. Actually - I've been basing my research on an updated version of the bill of materials, BOM v1.8, which includes numerous updates and notes on alternative parts.

In terms of the project as a whole, I have the following goals:
  • keep the hard costs as close to zero as possible,
  • source as many of the parts locally and from within Canada,
  • minimize (or at least be aware of) hidden costs,
  • document time and cost.
$Zero. I've been unloading stuff via Ebay, Kijiji, and Craigs to fund this project. I figure a tit for tat approach will just make the whole project more interesting. Not only do I get to get rid of stuff I don't need, I reward myself with a 303 :) I've been able to pool a healthy chunk of change into my pocket and paypal account so x0x SS#01 may very well cost $zero out of pocket when all is said and done. Here's hoping!

Get as many parts from Canada as possible, relative to overall cost that is. I'm sure there are a good handful of Canadians building a x0xb0x too. From what I have found so far, there are a several reliable sources here to cover the list. Because this is my first build, I do hesitate to go out on a limb with alternative parts and make approximations. I want a working unit first and foremost. I do need to rely on what has been proven to work. The other thing to note is that because the exchange is shifting gears these days, buying form within the country is getting to be the preferred method again. Since I'm working with a pool of US dollars, I'm not feeling the crunch yet but I will be taking into account what it would have cost based on exchange.

Minimize shipping costs and duty from these multiple sources. This is just one of those hidden costs that can really add up if one isn't paying attention to it. If I can make strategic purchases to minimize cost, all the better.

I want track the time and cost of this project. This mainly out of personal interest. What does it really take to build this thing? What did I pay for it and how much time did it really take? I've already made the mistake of not documenting the time I spent researching it. Because I've now taken on the additional task of documenting it, I want to account for that too. The advantage of tracking all of this is that I can at least separate what was actual build time and what was an 'external cost' of the project, such as writing this blog.

Now - the actual x0xb0x! My goals for this are fairly straightforward:
  • build a fairly 'normal' x0xb0x based on existing documentation,
  • add a power switch,
  • add connectors to all ribbon cables and main wiring for easy assembly / disassembly,
  • add sockets for rare parts and any other spots where it may be necessary or advantageous,
  • use different LEDs on first build,
  • use different knobs on the first build,
  • customize the ABS case with color,
  • customize the acrylic top and back panels,
  • try both the BA6110 & BA662A chips and decide on my preference,
  • review other documented mods that may improve the 'original' characteristics of the 303 sound and apply it here if the process is fairly painless.
I think this is good start. It's challenging enough, primarily aesthetic, and will produce a working instrument that will be ready to be modded even further if it interests me. I imagine building the first one will take a healthy amount of time anyway, so I would rather have an instrument I can enjoy first. Since I have to solder things like 40 LEDs into place, I'd rather do that the way I want it on the first pass.

x0xb0x SS#01: i. Preface

Like many electronic musicians, I've wanted a TB-303 for quite some time. Software emulation is all well and good (with the D16 Phoscyon taking the top spot for me these days) but after years and years of using virtual versions and junky presets on other synths and modules, I figured it was high time to stop chasing the dream and just go out and get one. It appears that my appetite for the true 303 sound can only be tamed by having at least one silver box in the studio.

This last year and a half has seen a significant price jump for a 303 though. For years a 303 cost about $1000. Now it's at least $500 more and appears to reach $3000. Someone called it a one trick pony somewhere and I couldn't agree more. Because $2000 is, imho, difficult to justify for this type of synth, I began ruling out the possibility of getting an original. Dammit! It looks like the real thing may be just beyond reach.

In my search for other alternatives the x0xbox came up. Other than it not being a "real" 303, it looks like it has everything I want and more: cloned circuitry, midi, DIN Sync for my 606, usb, options for mods, a healthy and helpful community, and plenty of documentation. Considering the total cost (minus my time) will likely be somewhere nearing the original price of a 303, I'd say this is the logical place to start. If I'm still not truly satisfied, I'll keep looking at the originals.

Since I've been getting back into electronics this last year, the x0xb0x will be perfect project because building it will be a great learning experience, it will achieve the same sound I'm after, and I won't feel like I'm sacrificing a classic instrument if I want to mod it.

this.onload {trace 'hello world!';}

So blogs are already out of style and twitter is the way to communicate with the world these days. How fitting that I'm starting this process now.

Personally I don't have time for either and I get the feeling I'm not missing out on that much. I'm not known for my writing skills. I find it a task. Ironically I talk too much so when I do have to convey my ideas to print, they tend to get long [but perhaps not interesting :)].

I do like stumbling onto the odd discussion that relates to a subject that interests me though. I owe heaps of thanks to all sorts of anonymous people out there who have helped me troubleshoot any number of issues. Thanks to those many blogs, I've been able to lurk on the web and find the answers I'm looking for.

So what I am doing here is keeping track of some of my projects. I just want a way to able to have some form of recall with ideas and projects I'm taking on. If this can become yet another resource for like minded people, all the better. You've helped me with your personal experience. Maybe I can help you with mine.