m00dawg

Muratic Acid is available at the local hardware stores here, or probably pool stores. I don't think you would need to important and certainly don't need to be going to eBay - HCl is a fairly common acid and you don't need it in a concentrated form. With Muratic Acid (which I think is 30%) and peroxide, boards etch extremely quick until you start making the Cupric Chloride. Here is some further instruction on how the whole process works. It's rather detailed depending on how interested you are in the chemistry. I did indeed find the boards in the gallery :) I'm going a tad bit more modular with my I/O boards but otherwise we appear to be mostly on the same page. I am still debating on the best option for the PSU though. I already have an MB-6582 compatible PSU which I can likely retrofit into my rackmount SID and use until I need to start doing the bipolar stuff. I'll need that for any op-amps or line-drivers I have and for the AOUT stuff but it may get me going while I work on the control surface and things.

Hmm that sounds to me like something going on with the filter section perhaps? Have you tried making a simple patch that sweeps along the filter range on both L and R? Also how about a patch that doesn't use the filter at all to see if that sounds clear. If you swapped your SIDs out than it probably isn't that so maybe a bad solder join on your filter caps? Sort of thinking out loud so I could be off-base but can't hurt to check.

Where exactly did you post them? :) As far as the S/N, good point, although I may stick with 12V for simplicity sake since the AOUT_NG requires 12V (and I assume the SSM stuff does too) and I already have to juggle 5V, 9V, -/+ 12V. At some point, space may be an issue if I wanted to stuff the synth with everything I want to cram into it :) In terms of FeCl, have you considered Cupric Chloride? It can be started by using Muriatic Acid (HCl) and Hydrogen Peroxide (O3) as a starter solution. It will etch super quick with that but will slow down considerably, and require oxygenation (or continual adding of peroxide, which can dilute the solution) so it takes a bit more work. The benefit is that it will last far longer as it can be used multiple times before you need to add more HCl or dispose of it. Slower etch times but better bang for your buck as far as home etchants go. Plus it makes a pretty green liquid when it's properly saturated with oxygen (that's how you know when it's good for etching).

Thanks! Since I originally posted this, we also released Cloud People Assassins. As the name implies, it's about those damn annoying flying guys in a few of the platform games (including Super Mario Bros).

Sounds reasonable to me.

Wow that PSU design sounds *nice*. A design like that is one reason I was thinking of just buying an off the shelf linear PSU, though they come with a non-trivial price-tag. I didn't think about the 6V swing between 12 and 15, good point. I went with 12 just because that's a popular choice with the filtering stuff (the AOUT, CV, SSM stuff). Don't know if 15 would be tolerable for those but if it would I could just as easily use that. All my outs will be going into my digital capture stuff so loudness isn't as much of an issue as it is to have clean audio. But "clean" is perhaps a loaded term when it comes to a SID chip :) As far as my designs, not all of them have been done on a protoboard or anything but most of them are simple enough to know it works in theory. There was one design of my audio jack module that had the pins on the wrong side, oops :) but other than that those boards can't really be any more simple. For the modular boards, I am wanting to use a wire-bus such that there is a single run of copper from start to finish (SID1 to my op-amp board as an example). Each board in the middle would simply tap into the wire. That was suggested from my local hardware group here because it is easier to debug and, while you can have modules fail, the audio bus as a whole will be fairly sturdy. The problem is that I was going to use the compression crimp DIL connectors but if I go with a mono solution, I would be wasting cables and connectors since I would only need to have 2 wires. So I'm trying to think of something that will do the same thing but perhaps with a bigger gauge wire and which would work with just 2 wires.

I mean the single MIDI port Windows sees would be limited to the speed MIDI typically runs at (if using a single port in Windows and using CORE to logically segment that out)? In regards to using multiple LPCXPRESSO's, you mean independently or somehow connected together? (The LPCXPRESSO is still very new to me :) ). This is more idle food for thought for me - I was fortunate enough to be able to get in on some GM5 action :) Though I had thought of retrofitting my SID and FM synths (once they are finished) so I can rock USB for them. GM5 makes that just a nice to have though.

Is it possible to simply map different channels of a single logical MIDI port to multiple MIDI ports on the hardware? So like channel 1-4 goes to MIDI 1; 5-8, MIDI2, etc.? Obviously can cause problems when you have a device that can use all 16 channels, and I'm guessing it could be easy to saturate the data rate when using one logical port. Still, could be a potential work-around?

Happy to share my work! You can find some info but I'll probably do yet another redesign. I want to go with a modular solution which I could use both for my MBSID and MBFM projects, as well as pretty much anything in the future, although I've gone back and forth on that. I like the modular idea because I can decide how I want to orient the plugs on the back and such and you never know when that might come in handy. The idea I had was to have direct outs which have a 1/4" jack and resistors to a mix out header. I tap the output of that header into a wire that runs the length of all the direct outs into a final mix out board which has an op-amp or line-driver. I've included my stereo version of the line-driver mix out but I rather like the idea of making the boards single channel which gives me some interesting options down the line. For my MB-SID, I would just have one row for left and one for right. Not the cheapest option, but I think it might prove to be useful in the future. Anyways I'm happy to share everything I have. I was going to throw this up on my MB-SID synth =sidr8tr]wiki page. If you want them before them, just let me know and I can post them here or PM them to you. I keep tweaking the designs (like going from stereo to mono out) so it's a work in progress :) )

Yeah I was going to go with +12, -12, +5, +9 PSU. I may use one of those linear ones found in the epic PSU thread a while ago, or I might make my own. Not sure yet. I'll post info about my stuff in the other thread (and yes, I'm happy to share!)

Hah oops I posted on the wrong thread :) (Removed and put it in the right place)

This may be worth checking out. They do it in three's typically so may not be ideal for boards you know you will only need one of but otherwise it is $5 per sq. in. for 3 boards. Not bad and, though I haven't used them myself yet, they have been recommended both here on these forums and from my local hardware group. It's nice to see options other than BatchPCB and Advanced Electronics, among others, for sure!

The IIC stuff could be used here as well, no? So that could allow tons of MIDI I/O at first guess :) I thought about using the STM32 core for MIDI I/O but it was too early in the design phase for it and overbuilt perhaps. Having an LPC doing MIDI I/O, maybe even with a neat display and routing capabilities would be pretty awesome I think!

Have you checked out CrystalFontz?

Have any info on balanced outputs with transformers? I was thinking of using an integrated audio line driver, but only for the mix out (which I don't expect to be all that amazing since, as you mention, it is a passive mixer design). I was thinking about adding volume pots to help adjust the mix out but typically I just live with the audio levels being all over the place until I go to master the track anyway. I'd like to have balanced outs for everything but that could push up the costs quite a bit, particularly if I rock transformers. Since the synth will be in the same rack as my sound card (probably right above or below it), the cables will be probably 1-2 feet. I thought about XLR connections but the sound card I plan on upgrading to has 1/4" anyway so might as well keep with it. I don't plan on moving things around much and if I ever did a gig, I'd just pick the whole rack up and move it.

=sammichSID#sammichSID_power_supply]Here is the PSU I use for what it's worth.

Some of those noises, while they are louder than they seem to be on mine, are just the nature of the beast. My 6581 in particular is one noisy dude. My 6582's are, by comparison, very quiet. The only thing I notice is small pops when loading or dumping patches and quieter ones when switching. I'm sure some of what you are hearing is also in my output, but I haven't noticed it much. Since you have 8580's yours should be quieter than the 6581's and, in fact, I thought 8580's and 6582's were basically the same for the most part. You may want to check to make sure the SIDs functionally work (all the oscillators work, filters work, etc.). As far as the temps, 55C is getting up there but a 12V linear-regulated wall-wart is what is typically recommended. The rectifier will drop the voltage a bit before it gets to the 7809 but the 7805 is just going to have to throw off a lot of heat. No good away around it on the Sammich since it was designed to be rather easy to build and one of the design trade-offs was using a simple wall-wart to power it (I assume anyway). I heard about some folks trying to put a fan inside but haven't seen any pics or anything. You could doublecheck your thermal compound to make sure you have a sufficient amount (but not too much) so that the heat is being conducted into the heatsinks properly. I'd be more worried about the SIDs myself :) I've been looking for very low profile heatsinks to use as the ones I used in the MB-6582 are too tall, but haven't found much.

Diggin' the FM sounds you have going on there! What did you use for the vocoder?

Looking snazzy! Looks like you put a good chunk of work into etching all that yourself. I certainly can't make my own boards look that good :P Excited to see the enclosure!

w00t well I'll have to redo my audio out board a bit now but sounds like that will work well. I think I'll keep with my modular idea (trying to figure out if I should have each module be a stereo pair or just make it mono which would make things require more space but lead to more flexibility)...hmm..

That was my thought as well. I think my mix out might be balanced though just for funzies since I was going to use an op-amp anyway (and the line drivers have op-amps in them). For the mono, I assume you hook RS to ground (so the tip is the audio)?

Good to hear! I'm definitely going to try him out for at least one set of boards I need for my modular passive mixer I've been working on. I actually need multiple copies of the board so the minimum quantity actually works in my favor :) And for this bulk order it means that, if people don't mind paying a bit more, we can order a small batch (20 at $10 a board or as little as 3 at $15 by my math).

I can't say if it will be enough, but heatsinks will make a substantial difference. It doesn't take much for regulators to get super hot without one which can be understandable since all the extra heat is only being radiated out a relative small metal tab compared to the size of even a small TO-220 heatsink. I was able to reign in heat from my first MB-6582 PSU by using just power resistors and heatsinks on everything and things were actually pretty stable.

The setup fees for BatchPCB irritate me. I'd rather they just roll that into the price because I never end up ordering anything from them because I'm waiting to lump all my boards together. But I don't finish some of those boards without first having boards so it ends up being this vicious cycle :) Certainly nothing against BatchPCB as I have had boards made from them and they do good work but these guys are good on price, seem friendly, are easy to work with - it's fantastic! As far as 50 boards, I just don't see hitting 50 for this run but yes at that size, Advanced Circuits starts to become quite economical. They irritated me earlier today though by not giving me the usual customer service treatment I am used to when I have asked them questions in the past. Their responses just seemed hurried and vague...

A friend at my local hardware meetup group recommended this place for doing some orders. They can both compete with BatchPCB for one off (with slightly different requirements) or medium-orders. In doing the match, 20 boards would be about $10/board which isn't bad. Otherwise it would be about $17 per board so if we can't get to 20 or 25 boards for the bulk order, this may be a feasible option depending on how much folks want to pay since it's still less than BatchPCB. I think they might be using a purple soldermask as well so that's fun! It's a smaller shop than BatchPCB and certainly than Advanced Circuits but it's much easier to submit designs and have real feedback so I'm inclined to give these guys a go. I may be getting some smaller boards done sooner than this bulk order may be ready and if I do I'll certainly share my thoughts.