Project 'Mbox SID'

[Flying Panther]

While an old C64 is resting and waiting for someone to rescue it's characteristic sound, I though now would be the time to give the SID a new life. At that point I came across the Mbox SID project, and now there's no turning back :)

At this point I'm planning on the functions I should implement and where to buy which parts.

I'm quite new to micro-electronics, so I might be going to say some stupid things (according to the Mbox SID-building veterans around here), but I hope you will correct me at those points ;)

Project outline:

What I'm planning to build is 4 times the SID with a Step C controlsurface plus some minor alterations. I will include an 8x bankstick-board as well as the LTC board for MIDI I/O monitoring and the MIDI Thru port. I also would like to include a mono 'mix-out' and headphone output, both with volume control. I have some rough ideas about this, but no clue if it's possible to (easily) realize this feature. The whole project should be packed in a desktop metal case, with the option to attach rack-ears.

The PSU:

I saw there are many topics about the PSU, but I couln't really find a satisfying answer to my questions.

I have the original C64 PSU, so it should defenatly be possible to use the 'optimized PSU'. But... The C64 PSU hasn't really proven it's stability for me in the past and I really dislike external adapters / transformers. From what I've read, the main issue with using another PSU is the voltage diffrence (5V and 14V) and the signal/noise ratio. For the purpose of testing I could still use the optimised C64 PSU, but in the end I'd prefer something more stable, safe and 'new'.

Would it be a good idea to get 2 separated PSU's, like a 14V DC and 5V DC PSU or maybe a 5V DC and 9V AC PSU using the optimized PSU scheme? I couldn't find a real 9V AC PSU, only external adapters or 230-9V transformers. The transformers are quite cheap (€3-10 compared to €30 for a 5V PSU) but I have the feeling it can't be that simple: Putting a transformer on 230V and have 9V without the risks a real PSU will exclude. Also 14V DC PSU's seem to be non-existing or hard to find.

The mix and headphone out with volume control:

What I had in mind is to route the 4 individual outputs to a volume pot-meter. The resulting (mono) audio will be forwarded to one mono output (mix-out) and also to a stereo output for the headphones. (ofcourse no true-stereo will be achieved here, just the same mono-signal on the left and right channel). My 'only' problem is that I expect the 4 SID outputs to be at line-level and don't know how to combine these four channels and get line-level again. I also must say that I didn't really read myself into this, which mainly is because at this moment this isn't a big issue, but it would be nice if it's possible at a later stage 8)

The controlsurface and design:

When building, testing and completing the Mbox SID I will use a cheap plastic box; There's need to look beautifull at this stage. This will also give me some space to make adjustments to the layout without making a new metal frontplate. I'd like to change some minor things to the Step C controlsurface. I'm thinking of replacing the detented menu encoder with a pushable one. The knob function will be replacing the menu button. I also like to have knobs with integrated leds for the SID-selection, CC, Link and Edit selection, since those buttons will only trigger one LED. Buttons that will switch multiple leds will still be 'blind' knobs with independent LED's. These adjustments are not essential, but just a nice thing to implement and give the design some 'personal touch'.

The parts:

I'm planning to get the main parts from www.mikes-elektronikseite.de and the rest from the local electronics shop and www.conrad.nl.

Parts to get from Mikes':

1x MIDIbox SID 8580 / 6581 + CS (Kit)

3x MIDIbox SID 8580 / 6581 (Kit)

4x PIC18F452 (Bootloader)

1x LTC_V2 (Kit)

1x Bankstick board

1x Eeprom 24LC512 for banksticks (8x)

Other parts to get:

- 2x20 LCD

- Buttons

- Potmeters

- LED's

- Vectorboards (for the buttons, pots and LED's)

- (Ribbon)cables

- Cable connectors for prints

- Midi port connectors

- Jack connectors

- Parts for the optimezed PSU, or other solution

- Some ugly plastic box ;)

I've read in other topics that people ordered PIC's from SmashTV, even when they live in europe. Are there any diffrences between the PIC's Mike offers and the ones from SmashTV, or are there other reasons why the PIC's from SmashTV seem to be preferred?

In addition to all this, are there things I spefically should or shouldn't do (like adding or removing / combining features to the controlsurface)?

Ofcourse all comments are very much appreciated :)

[Twin-X]

There is a diffrence yes but it does not influence the project.

My pcb's were from mike. I had no problems with it.

If you like silk screening (where the compenents are printed on the pcb) then buy the stuff from smash.

[toneburst]

Also, Smash's kits have a 'solder mask'- a surface coating so solder only sticks to the pads around component holes. Makes it nice and easy to solder, but I've found it tends to melt and make the surface of the PCB look messy when desoldering stuff. Hopefully you won't make as many mistakes as me, so you won't ever have to desolder ;)

I bought kits from Mike and SmashTV. My SmashTV Core and SID modules are now both working, but I haven't so far managed to get the Mike's MIDIShop Core board to play ball. Think this is more a reflection on my incompetence than the quality of Mike's boards though....

Alex

http://www.toneburst.net

[Flying Panther]

First of all, Twin-X and toneburst, thnx for the reply's and help with the prints :)

So it's been a while since I first posted here, but there is some progress in the project! I made a plan on how the final result should look like (it might turn out a little diffrent but hey, plans can change ;)). This is how it should look like when finished (4HE 19").

At the moment I'm collecting all the parts and tools needed to start and complete the project. I got most of the parts, and I found a nice red backlit 2x20 LCD (about $27,-) on www.crystalfontz.com, but using their calculations the shipping will be around $37,50. Since I don't need other parts or anything from crystalfontz, the lcd will cost me about 65 dollar :/. Maybe someone here knows a place in europe where they sell similar LCD's so I can reduce the shippingcosts a bit?

Now for the PSU. The main problem is I want to build-in an active mixer which combines the four sid outputs and creates a mono 'mix' output and a headphone out. This means I have to use an op-amp and need a symmetrical power supply. I'm not sure what to do with all the psu's because now I will need a 5v DC for the cores, a 12v AC or DC for the sids (8580 needs only 12v input if i'm right), and a 9-12v symmetrical DC for the mixer.

I'm thinking of using a 5v DC and 12V DC PSU from Cincon and this kit (or maybe build a similar schematic myself) with a 2x15VAC transformator for the symmetrical psu. Only problem is that this option uses a lot of space. Are there any options to improve this?

I thought of the option of getting a big 15VAC transformator, which can feed the sids and the symmetrical-schematic-thing. But it's stated everywhere you'll need a 2x15VAC transformator for that, so I don't think that will work very well.. ???

All help will be appreciated!! :)

[b-funk]

hi,

i just had a short look at your last post, so i can´t give you answers, BUT: i realized that you said you will supply the 8580 with 12vdc. please DON´T do that. it needs 9vdc.

best wishes,

tobias.

[Flying Panther]

i just had a short look at your last post, so i can´t give you answers, BUT: i realized that you said you will supply the 8580 with 12vdc. please DON´T do that. it needs 9vdc.

Ah, I forgot to mention that I will use the 7809. But that might indeed be a bit double, having a DC psu and stuffing the 7809's. Maybe it would make more sense to use a 9v DC psu and leave the 7809's out?

[Flying Panther]

Maybe I should just attach the image, instead of linking to it ;)

[SLP]

In V2 the "Link"-Button will have another function.

I think It will be used to switch the clock-sources.

You should change the text.

[Wilba]

I think the "Link" button will be showing a menu for controlling L/R SIDs, which engine to use, etc. I'd hold off making a panel until V2 is released (or close to release).

For example, now there's no fixed modulation matrix, there are modulators which could be a combination of envelopes, LFOs, analog inputs, another modulator output, velocity/pitch value etc. Modulator 1 could be LFO3 * Env2  ;D  So the static E1, E2, L1, L2,... text up the top is only the default setup, it could just be 1 to 8 for the modulators. Similarly, you can output to the three oscs' pitch and PW and filter and also volume (for L/R or both SIDs) so an 8x8 matrix might be useful to have. If you're not afraid of doing some custom coding, go for dual colour LEDs on the matrix to show L/R or both SIDs ;D

[Flying Panther]

It seems I have to read in on the Sid V2 options ;) My plan was already to first complete the inside of the box and then, when V2 is (almost) ready to make the casing (and adjust the frontplate if necessary). But.. I thought V2 didn't involve hardware changes (exept for extra 2x Sid per Core and new Core PIC's). Since that thought seems to be wrong, I'm going to read into that again, and check the customizations I might need in the control panel.

Just to be sure, If I make my Core and Sid modules now, I can reuse the Core boards (swap the old PIC with the new V2 version), add an extra SID to each core and leave the 'old' Sid modules as they are?

[SLP]

Similarly, you can output to the three oscs' pitch and PW and filter and also volume

I think TK didn't want to offer the Volume as a Modulation target since the resolution

is only 4 bit

[TK.]

Yes, the resolution is very poor and you can hear some zipper noise when the volume is modulated.

On the other hand some cool stereo effects can be realised - like this one:

http://www.midibox.org/midibox_sid/mbsidv2_demo2.mp3

Who needs a Leslie? ;-)

Best Regards, Thorsten.

[Wilba]

Flying Panther: It's been stated many times by TK that the firmware will be compatible to existing control surfaces like his one... I'm only suggesting that you might like to put in a few V2 features into your panel. You don't have to, it's just a suggestion.

You will be able to reuse your PCBs, the only hardware change is the CAN bus, which you can add later.

[Flying Panther]

The stereo volume effects sound great! Too bad it also comes with noise, but I guess we can't have it all ;)

Wilba: Thanks for the explanation :) I'll consider the extra V2 features on the layout, don't know yet what to implement and what not, but hey, dual color leds are always a cool feature :D

[Flying Panther]

I'm still struggling with the PSU and I thought of a new way to power all components (see the attached scheme). I'm not sure this will work, but I'd like to use a  230V to 2x12V transformer, with 12V out one and 12V out two. Both 12V one and two will go to a circuit that transforms the two 12V AC inputs to a symmetrical 9V DC output for the opamp. The 12V one will also connect to the four Core modules, and the 12V two will connect to the eight SID modules (V2-setup).

If this will work, would a 2x1A transformer do the job? Or should I get a 2x1.5A one just to be sure?

(SID's will consume about 100mA each, Core's, LED's and LCD also around 800mA total I think?, don't know about the opamp-circuit)

[Wisefire]

if im correct.. you want to connect a 12v line to a core with a 7805.. thats not a good idea.. the 7805 will run very hot..

[Flying Panther]

Hmm.. I was hoping that if I supplied every core module with a separate 7805 it wouldn't get that hot. So this means I'll have to get the voltage to about 7 or 8 V before feeding it to the Core's?

To get an idea of the heat, what kind of temperatures can I expect when I connect 12V to a 7805?

[Wisefire]

expect that if you touch it. itll burn your finger.. and that you'll damage your 7805.. it depends of how much current your setup behind the 7805 is pulling.. but expect a core with an LCD to get it hot enough to burn the 7805 out..

[Flying Panther]

In that case, I might not connect the 7805's directly to the 12v AC ;) Thnx