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Posted

Can´t wait to start build again...

Right now i´m middle of changing flat so everything are in boxes..(Not midiboxes) ;)

But now I have something to look forward to. ;D

Christoffer

Posted

Thank you! :)

I've good news: I found out the trick how the original C64 power supply unit shifts the 9V AC to a higher voltage level in order to power the SID. It just adds the 5V DC via a 1N4001 diode - this DC voltage is not used to power the C64 logic...

Schematics can be found here:

http://www.ucapps.de/mbhp/mbhp_sid_c64_psu.pdf

http://www.ucapps.de/mbhp/mbhp_4xsid_c64_psu.pdf

Note that the ground connections have to be wired like shown above in order to avoid 50 Hz buzz on the Audio Outs.

sid_cs_psu.jpg

Next step will be the integration of 4 Audio Outs, a USB plug and a second MIDI In/Out into the C64 case... ;-)

Best Regards, Thorsten.

Posted

Hi Matteo,

possibly yes - I've programmed the MIOS based firmware in a way which allows me to use all algorithms with multiple databases, so that another SID could be driven in parallel - in theory. But in practise I expect some effort for the details. First I want to finish all the planned features and projects before I do such a step.

From my personal point of view this is a low-priority task

Every additional core module just only costs about 20 EUR

As I already built the 4-core solution, I don't need it for myself, it would only be some kind of sport to demonstrate the power of the PIC18F...

A PIC18F core which drives 2 SIDs will not be able to handle the control surface in parallel (due to RAM limitations). And controlling SIDs without the control surface makes no fun. So at least two cores would be prefered anyhow.

So in fact, please don't expect a release this year.

But if somebody else with programming skills would like to modify the application for this option - step forward :) (I can provide some more technical details if required)

Best Regards, Thorsten.

Posted

Fast, faster, TK!!!

Just build the case this weekend for my 4xSID and designed the frontplate in advance.

Coming back here: Tadaaa! Man, thats timing. Really BIG thnx!!! (again...  ;D)

/edit: Am I right that the open DOUT Pins are just multiplexed for the LEDs of the Modulation Matrix? Just cant wait to solder that stuff...

Posted

Hey, TK: Is there something like a Pan Control planned for the single SIDs? Something digital?

If not, I will build some additional analog pots in there to control the pan of every SID (since this is not much additional work). Then I just cant save those settings. And something like a Pan controlled by a LFO or so is always great (especially with 4 SIDs  ;D).

  • 2 weeks later...
Posted

Pan control will be possible with the AOUT extension :)

In the meantime I've revised the PSU circuit for the best signal/noise ratio. No 50/60 Hz hum and no digital HF noise in the background anymore.

http://www.ucapps.de/mbhp/mbhp_4xsid_c64_psu_optimized.pdf

Results:

  • no heat source within the case anymore, since the +5V are regulated by the external C64 PSU
  • 6581: -76 dB signal/noise ratio
  • 8580: -90 dB signal/noise ratio (CD quality!)

Please don't ask if your own PSU variant brings the same results - it was a long try and error session until I found out this solution ;-)

midibox_sid_cs_inside.jpg

Best Regards, Thorsten.

Posted

unbelievable!  ;D BTW TK, the new mb sid page is very nice, I like Ian's pile of c64's, but I'm not sure if I can cannibalise my old c64 :'(, but then again....

BTW, what is wavetable synthesis? is it loading a waveform into the chip or something? (If this requires a long explanation, then just tell me to look on the net somewhere!)

Posted

Hi Steven,

the term "wavetable" is an artefact from the good old C64 days. It has nothing to do with audio samples, but with CC controllers which are played sequently - so fast, that the resulting noise sounds like a new waveform. There is a lot potential in this kind of synthesis, especially when you are able to control any parameter (not only the pitch, the waveform, the sync/ringmodulation switch, but also LFO/envelope/filters and also the wavetable CC assignments and the rate --- really any parameter) like with the MIDIbox SID ;-)

Here are four short preset examples:

http://www.ucapps.de/midibox_sid/mbsid_wt_demo.mp3

First three sound patches: the wavetable rate (speed) is varried from 0 to 119

Last sound patch: this is one SID playing one patch - it should demonstrate that wavetables are not only usable for C64 like drum sounds.

Best Regards, Thorsten.

Guest Xcen
Posted

Good work TK :) Very nice panel as well!

Can't wait to get home and listen to this mp3

oh and you should switch to OGG :) hehe

Posted

Yes, it will. I built my first part of the SID just with two SIDs and Cores. Everything fine. You can change to SID 3 and 4, but naturally nothing happens there.

The first two SIDs worked without problems,

Posted

wow! Just saw the new section on the site!!

I want more pictures hehe :D

This is really a cool box, kudos again TK!

Posted

Hey T...

On the powerfix pdf you've done, I'm assuming thats for the older C64 psu ye?? Can the 8580's be used with the 6581 psu too or is the 8580 wallplug good to be used too (with the 8580s o course)?

Reason i ask is cos you've said you had both the 6581's and 8580's working - are you using them with they're own wallplugs, but with the fix as in your pdf?

One more thing, are u still running with the 6n8 caps on the 8580's or have you found another value?

Great work!

Dan

Posted

Hi Dan,

no, an additional PSU is not required for the 6581 and you can also use the C64-II PSU instead of the old one. See also this article:

http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=parts_q;action=display;num=1057652794

You cannot improve the filters by changing the caps. But MBSID V1.5 will come with a special option for the 8580 which enhances the filter range. In the meantime I've realized that the 8580 filter is better than the 6581 filter - see also this MP3 which has been recorded with a single 8580:

http://www.ucapps.de/midibox_sid/mbsid_v1_5_wt+arp2.mp3

(MBSID V1.5 Presets, Patch #64 :-))

Best Regards, Thorsten.

Posted

But please tell me that this feature will be somehow also available for the 6581. After you said that the 6581 is better, I bought four of them on ebay and now the 8580 is better? *ARGH*

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