Hello and some questions

[dorremifasol]

Hi everybody!

This is my first post here. I have finished mounting the basic of my first Midibox SID v2 ( bought in http://www.avishowtech.com ). I plan to make one box with all the chip revisions inside. I must say that I'm an absolute dumb with electronics, but my soldering skills seem to be good enough to build this fabulous instrument.

Yesterday at last I could test the PCBs and they seem to work. I couldn't edit any sound because I don't have a control surface yet. I expected to find at least a simple computer program to edit presets for the SID v2 version, but I could only find JSynthLib which only works with Midibox SID v1.

- First question, is there any computer editor to work with Midibox SID v2?

- Second one, how could I change the engine on the fly? I haven't found any CC or NRPN to change between bass, lead and multi engines.

And now with the filter. My first unit uses a 6581R4 which I really like for its distorted filter. The problem is that it seems that I can not change the cutoff frequency. When applying resonance I hear that it increases the distortion, which was expected, but changing the cutoff doesn't seem to produce brighter and darker sounds, it's always set at low level but audible (nice sound by the way).

I have read here in the forum that the capacitors C1 and C2 are used to control the cutoff frequency range.

- Do they have positive and negative poles? May I have soldered them in a wrong way?

- What would be the symptom of a broken filter?

- What can I also check in the PCB?

For now I'm using an external power supply at 9 volts and 500ma for both PCBS and the LCD (http://shop.tuxgraphics.org/electronic/lcd.html?id=1c552a the blue one), and it seems to work fine, but the 7805 seems to heat up a lot. Is this normal?

Thanks in advance for your answers!

EDIT: I have attached an audio file of my 6581r4, in case someone could indentify the filter problem by ear.

this is how it should sound in a 6581r4: http://www.se2a1.net:40000/soasc/MOS6581R4/MUSICIANS/F/Follin_Geoff/Solar_Jetman_T01.sid.mp3

8580r5 here: http://www.se2a1.net:40000/soasc/CSG8580R5/MUSICIANS/F/Follin_Geoff/Solar_Jetman_T01.sid.mp3

Isn't that tune wonderful? :)

Cheers,

Albert

solar jetman.mp3

[dorremifasol]

UPDATE:

As there were no responses I started to try things... I replaced the filter Caps with the ones found in the C64, with the same result. Then, when I was almost sure that I had a defective SID, I realized that the power supply was set to 9 volts (to be safe), so I set it to 12 volts. I also put a small heatsink in the core module since the same power supply is feeding both circuits. And now the filter works exactly as I expected!

So after all, the amount of power feeding the SID PCB is very important for the filter to work. I will attach a new audio file.

Anyway, my first two questions remain unanswered:

- Is there any computer editor to work with Midibox SID v2?

- How could I change the engine on the fly? I haven't found any CC or NRPN to change between bass, lead and multi engines.

I'm really eager to start programming my own sounds and I still don't know how to do it :/

I guess I will continue listening to Follin SIDs until then (^_^ )

Next step... optimized power supply, control surface and the 8580r5.

Cheers,

Albert

solar jetman v2.mp3

[napierzaza]

Yes,

Your chip revision takes 12v.

jsynthlib should have a virtual control surface for the SID.

http://www.ucapps.de/jsynthlib.html

Not sure about the cutoff.

The caps aren't polar.

The 7805 should be fine, it get's hotter if you're using a large current or are going down from a higher voltage because it "eats" the extra volts. So if it's 12v to 5v it's a 7v difference, as opposed to 9v which is 4v.

Also make sure you are running a "linear" power supply and not a "switching" type.