Jurbo

What happens to the sound when the filter capacitors differ in value? Does it cause two separate resonance peak frequencies? Does it cause a softer cutoff, less abrupt filtering? Does someone know the theory on this? I'm asking this because after some cap fiddling, I found a very nice sound on my 6581 with ceramic caps (probably not too closely matched), as opposed to somewhat closely matched (5% tolerance) plastic ones. The filter felt softer in character around the cutoff using the ceramics than the plastics which gave an almost on/off character to a sound fluctuating around the cutoff frequency. 6581 filter seems to be very sharp at the cutoff, I'd like less abruptcy. So, anyone with actual theoretical knowledge on this? Thanks!

@DrBunsen - Now there's a wild idea! Haven't tried it, might give crazy results... I suppose you could get the benefits of the stronger 8580 filter plus the warmer basic sound of the 6581. Of course, in such a loop there might also be massive self-oscillations to watch out for... Hmm, maybe I'll try it in the near future!

Sorry for bumping ;) Just checked a bit how this loop thing works - a lot of different textures can be achived with a 8580, but with a 6581 (week 4183), seems there's no self-oscillation and little effect at all (I was able to get just a little gurgling effects on some sounds). On the 8580, I thought it might be good (for guys like me who don't like huge high frequency self-oscillations) to limit the effect of the feedback loop (possibly with a 100 kohm resistor in series with the pot). Just wanted to share my quick thoughts on the matter... :)

Hmm, yes the 22 nF works ok, and the low end blockiness of the filter definitely went away, while introducing a slight blockiness to the higher mid area. However, I felt the upper end just a bit restricted, so I'll test with 15 nF and 10 nF when I get some of those in my sweaty palms... Any comments on the Wima FKP2 range of capacitors - should be high quality, but does someone have actual SID experience of them?

Whoops, it totally is so! So I've been happily wailing away on my 8580 with just 4,7 nF for a couple of years... Thinking that even they were "a bit larger than usual" for the SID... I'll definitely have to check where the 22 nF's will take me! Thanks a lot for the clarification, I think I have some things to try and find out... ;D

Hello! After a silence of a couple of years I'm back lurking the forum, getting ready to upgrade my MBSID V1 to V2. I think I have pretty much understood what supplies I need for the upgrade and will be ordering stuff soon. But to the topic - the default filter caps for the 8580 are often referred as 22 nF on this forum but also in many places around the net. Is this really correct, or should it actually be 2,2 nF? I found a schematic: http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/252312-right.gif and it clearly states 2200 pF as the caps, doesn't this mean 2,2 nF? My MBSID 8580 caps say 4700 on them (value chosen by testing different caps way back then, number means pF's I think), meaning 4,7 nF, right?

Heh, it's nice to see my box getting some attention again! Not that there's much going on with it, just some occasional, pleasurable jamming. Euphoricgrey - Don't know what size leds you SHOULD use, but I used 3 mm ones. ;D

Correct me if I'm wrong, but wasn't the E board ("short board") only equipped with 8580's? That would mean that the SID socket gives 9 V DC. 6581's were used on the earlier, longer board, although housed in a similar newer style case. 12 V DC at the SID socket. Here's a tip: case held together with plastic clips means short board, case held together with screws means older board revisions.

You can use a c64 without a sound chip. Joysticks will work, too. What will not work, are paddle controllers (controllers with a potentiometer).

I have only seen socketed SIDs, both 6581 and 8580. This means about seven machines. Then, I have seen only socketed roms, all other chips have always been soldered to motherboards. Weird... :)

Rotary encoder = datawheel, yes. About your order - I'd say get more ribbon cable, to make sure you're ok. I was really surprised at the total amount of wire I spent. And the MIDI cables are really cheap at Joerg's, too. Other than that, your order seems fine, as you said you'll get the rest of the components from a friend (I wonder how anyone can build a full control surface without having some connections in the business as some of the parts will be hard to get or just insanely priced). This is just a thought: I burned the bootloader myself with the JDM module I built (the MBHP burner is its up-to-date replacement), and I really got a confidence boost from realizing that I was able to build a working device from a bag of little tidbits. So making the burner was good practice and a lot of encouragement for the actual MBSID project. :)

Is the 7809 regulator in correct orientation? Have you checked the PSU that the 9VAC lines work? If I remember correctly, there is a fuse for 5 VDC and another one for 9 VAC inside the PSU.

TK - The slave core doesn't need to be updated? Hmm... Then there must be something else wrong with my box, as the joystick didn't change the slave filter. Well, I'll have to look into it more closely. Anyway, did some SID jamming yesterday night and damn it was cool... ;)

Okay, finally got to test the hack, and damn, it does work! :) :D ;D 8) The pots are in different order (earlier I had up/down cutoff and left/right resonance, now it's swapped) but I'll probably be able to figure that out myself - if not, I'll do some light soldering! The display doesn't update when using the joystick? Is it meant so? I mean, I'm glad it doesn't, as now my default filter values stay intact and the stick doesn't "edit" but allows "live" modification. Do I have to load a new version of the slave file, too? The slave sid doesn't seem to be controlled by the stick, only the main one. I'm asking this, because my main sid is a 8580 and the slave is a 6581, and somehow when I run Convert.bat to create the syx files, I only get a changed main.syx file. Anyway, great job, Offe, this really cheered my night up! :)

8580 + 6581, rocks big time. 8) I enjoy playing the same patch in stereo, I love the effect that the small differences of the chips make. By the way, there is so much to be drawn even from a single oscillator, that four sids are really needed only for some heavier sequencer use, in my opinion. The key is to have the full control surface, because it makes morphing the sound easy and intuitive. You get the SID's soul at your fingertips! :P The filter changes a lot by using different capacitors, mine are a bit larger in value than the stock ones (I use 4,7 nF on the 8580 insted of 2,2 nF and 1000 pF on the 6581 insted of 470 pF). I think I get the filter range more usable, as the original values give too much playground in the highest treble, where I find it less useful. Oh, the initial issue on different chips - whatever you like best. You'll know once you have played with both (and you will probably want both after that...). For regular C64 use, the 8580 sucks because the digi-sounds are useless (imagine loading up Skate Or Die with the title music lacking the crushing guitar chord)...

Damn, I'll have to try this out tonight! Huge thanks, Offe (I guess there are others that will benefit, too)! 8) Offe, as you seem to be able to get around the code, do you think it would be possible to use the remaining AIN pins for the LFO wavefrom thing that TK has introduced?

Yep, the casing is the hardest part, although there are less difficult solutions, as browsing through other people's boxes will show. Take a tour around the gallery. And then take another tour of the gallery. And then take... You get my drift, I'm sure. :) Some pointers that might help - Think what materials you have easy/cheap access to - Think what tools you have easy/cheap access to - Think who you know who might be able to help you with skills / materials - Think where you will place your box when using it (easy reach, a fitting size) Then the more detailed planning: - Plan the casing very thoroughly before doing any actual work on any materials (you could even make a cardboard preview version!) - Measure how much room does an encoder/button/lcd/module need on the inside - How far apart must the encoders/buttons/leds etc be to be usable (depeds on hand size etc) I'd go as far as saying that good planning is two thirds of the job. And don't be afraid to try many things you have never done before!!! ;)

dcreatorx - You can use RCA (cinch) or 6,3 mm (1/4 inch) jack, whatever suits you best. What decides this is the equipment you are going to use to get the sound out. Most mixers accept a 6,3 mm jack, so that's what I went with. Jack->jack cables are thick and durable. And, when you are connecting to RCA equipment, the jack->RCA adapters (with RCA->RCA cable) are less clumsy and give a better connection than RCA->jack adapters. Although I'm sure other opinions exist... ;)

@ Ringmod45 - thanks a lot! The three extra buttons (the one next to the encoder is the menu return button) don't do anything right now, but they can be wired and programmed for extra functions. I basically added them for future expandability and cosmetics. But, as Thorsten has said, he will be making future changes to MBSID application in such a way that the default control surface will need no changes. So it's up to me to change the application if I want to use the extra buttons - they probably won't be seeing much use... ;D

Offe - I'd be extatic if the joystick system will work again... I wish much success to your experiment!!! Thorsten - You are definitely giving more possibilities with your new system, I understand that after giving this thread more thought. However, I'm still hoping that Offe's hack will work and the joystick will work like before. And by the way, there are seven analog inputs on the Core, right? In my wishful dreams this would equal two inputs for Cut/Res pots, five for LFO sources... ;D

Hi (speak of the devil...)! My lovely MBSID has been lying in the corner of my very messy table for a few months, because I haven't been able to figure out the filter joystick implementation for 1.7a... I tried several ways to include the old driver code in the main file (?) but I just managed to crash the whole MIOS. I have been scared to post stupid questions so the box has been lying silent... Well, I've also been busy with other projects like building a wooden slot car track etc. Ok, so the filter joystick can't be done anymore? Oh, bugger... Yes, the resonance is not that finely tunable and not all that effective, but I did find it usable anyway (on 8580 at least). But can the cutoff still be implemented through the joystick? The reason I still would want to get the stick to work is (besides the obvious fact that I have it built...) that I did enjoy making small variations at the "nasal edge" of a fat lead tone in real time... Anyway, once I have the box running again, I will donate some sounds for the MBSIDders...

Yep, the thing doesn't have a separate soundchip, so you can't make a MBSid from it... However, there's something you probably could do: As you have probably seen at several hacking sites, you can attach a PS/2 keyboard to it, and a Commodore disk drive. Download the Prophet 64 software synth, and you will be able to jam with the emulated SID on the PS/2 keyboard. 8) Haven't done this myself - but I'm going to get one of those sticks for hacking purposes (nothing MBSid related, though).

Wow, that Thorsten sure has an ace up his sleeve for every situation! 8)

Kokoon, you are right about the blocky behaviour of the 8580 filter in the lower end - a fast sweep causes a metallic boinging sound and a slow sweep goes in audible steps. It's one of the reasons I switched from 2x8580 to 8580/6581configuration. The 6581 filter seems to go through the cutoff range smoother, and the 6581 filter doesn't turn the sound completely off in the lowest values like the 8580 filter does. Then again, the 8580 filter is more pronounced and effective with a better resonance, so there is good and bad in both chip types. :)

From Finland, yes... I work in advertising / signmaking / decoration so we use a cutter all the time at work. Cutters use vector graphics as cutting paths so if you want to try the method, find a local signmaker's and ask what kind of file format they can use. I'm happy about using the method, but I used it mainly because I had easy access to it. Otherwise I probably would have done it some other way (printing and many other methods will surely be less work and cheaper, too).