Perplexed Newbie. Need help.

Design Concepts
1

Hi everyone. I am new to the MIDIBox forum although, I have been popping in every so often for several years now and I (like many others I see) am curious as to how I could implement a MIDI Controlled Programmable Guitar FX Switcher something akin to the GigRig or Carl Martin’s Combinator2. I have been going thru many of the threads on here and other sites (GEO FX and the DIY Stompbox forum in particular) and my head is spinning. I have nonetheless came to the initial conclusion that I could probably start off with GeoFX’s “Remote Footswitch Bypass with Relays and CMOS - Conceptual Design” as that seems more easily expandable but, I would still need a way to program patches and banks. This is where I believe the MIDIbox can be used. Basically, I was figuring I could double up on GEOFX’s “Local Footswitch Box” design, thereby increasing it to a total of 12 Loops/Stompboxes (which is what I need) and then, use a MIDI Core module and DOUTx4 to switch whatever combination of FX I wanted in or out (Patches/Banks) via footswitches. Obviously, I could theoretically have 144 patches (12 x 12) but, I’m sure I could live with half of that. :slight_smile: Of course, this assumes I even know what the hell i’m talking about which…, I don’t. For example, i’m assuming that I don’t need the “Remote Footswitch Box”, which has one 74C14 and 3 CD4013 chips in it, as I will be replacing that part of the circuit with the Core and DOUT modules. I also don’t know what the output voltages of the DOUTx4 will be or, if they will be capable of driving and switching the relays on or off in whatever combination I set. Should I use the AOUT module instead? What modules do I need to create and save the patches and banks to? Ultimatley, I want to be able to switch from say, a clean/phase/echo patch to a fuzz-face/uni-vibe/octavia/echo patch back to a bluesbraker/envelope filter/echo patch at the press of one footswitch. I figure a pedalboard with 8 footswitches for selecting patches in a bank plus, 2 switches for bank up and bank down, as well as, some way of saving and editing patches via footswitch. Of course, an LCD for use as a simple UI showing Patch numbers and Bank numbers, etc… Maybe some LED’s for each switch. Am I reaching too far? I have no idea if i’m on the right track but, i’m sure it’s possible so, any help would be appreciated. Maybe, if someone could at least tell me what my limitations are with the Core and DOUT mudules, that would be a start.

Thanks again, everyone.

2

Hello!

You’re probably in the wrong topic but I leave that to the moderators.

You could have a look at:

“FX looper with MidiBox”

http://www.midibox.org/dokuwiki/flo

<___base_url___>/index.php?/topic/10910-guitar-fx-switcher-with-midibox/page__hl__fx%20looper&do=embed

It’s a design idea I did a while back but never did a complete build. I’m currently too busy with other projects (like tube guitar amps) to finish it.

Would be great if somebody picked it up and continued it. :slight_smile:

Another idea would be:

“The Pedal Box and Pedal Board Thread”

<___base_url___>/index.php?/topic/9081-the-pedal-box-and-pedal-board-thread/&do=embed

Regards,

flo

3

Hey Flo. It’s a small world, huh? What tube amps are you building? I built a few from the AX84 community. I started with the Hi-Octane kit, which I then upgraded to an SEL 20W with an EL34 in it. A couple of months ago I built an L2L Club which is a 20W Push-Pull amp with a set of 6V6’s in there. Presently, one of the members from the community is taking a look at it, as I just can’t seem to find the source of this annoying squeal I get when I plug a guitar in and dime the knobs. I was able to get it to about 1/4 MV without any squealing and then, once I tried to get any more volume out of it, it would start to squeal. I’ve tried all sorts of stuff and was going back and forth on the forum for a while. Hence, one of the designers of that project eventually offered to take a stab at it. I’ve also built about 20 pedals and my own pedalboard but now, I need something to put it all together without tap dancing on stage.

So yeah, I defintely want to pick this up but, like I said in my first post, right now I need some basic info about the Core and DOUTx4 modules before I proceed. First off, i’m assuming I only need one DOUTx4 module, of which i’ll only be needing 1 and 1/2 of the 74HC595’s, in order to run 12 relays/loops/pedals, correct? If that is so, I can just vectorboard 2 74HC595’s and associated components, correct? Will I be limited to 7 patches per bank using the Core and DOUTx4 module? This is important as I was hoping to have 8 switches (one for each of 8 patches) on my pedalboard. How many banks can I get out of the 2 modules? I am shooting for something like 8 banks with 8 patches in each. Is it neccessary to use the ULN2803 to drive the relays? What other relay drivers could I use? You suggest using Mini DPDT relays but, which ones should I use? 5V or 12V? Does it matter which one I use? I’m assuming the banks and patches will get stored on the Core unit. Is that correct? If not, then I guess I will need some Banksticks in order to store all these patches and banks, correct?

I have a lot more questions but, if someone can answer these few questions, I will have a good start. Again, I am new to PIC based electronics and MIDI so please, have mercy. I know these questions probably sound dumb to some of you but, as you know, it’s not easy to navigate thru stuff you just aren’t familiar with. Ask me about scales, modes, polyrhythyms and the sort and i’ll have no problems but, MIDI and PIC? Anyway, I appreciate any help.

Thanks

Hello!

You’re probably in the wrong topic but I leave that to the moderators.

You could have a look at:

“FX looper with MidiBox”

http://www.midibox.org/dokuwiki/flo

<___base_url___>/index.php?/topic/10910-guitar-fx-switcher-with-midibox/page__hl__fx%20looper&do=embed

It’s a design idea I did a while back but never did a complete build. I’m currently too busy with other projects (like tube guitar amps) to finish it.

Would be great if somebody picked it up and continued it. :slight_smile:

Another idea would be:

“The Pedal Box and Pedal Board Thread”

<___base_url___>/index.php?/topic/9081-the-pedal-box-and-pedal-board-thread/&do=embed

Regards,

flo

4

If you have no experience with MidiBox nor with PICs I suggest to make it a bit simpler like I minimized it in:

“FX looper with MidiBox”

http://www.midibox.org/dokuwiki/flo

<___base_url___>/index.php?/topic/10910-guitar-fx-switcher-with-midibox/page__hl__fx%20looper&do=embed

which is:

You can always extent later. Remember there’s a lot to learn and do before even the simple one is done.

About using relays see: http://www.midibox.org/dokuwiki/flo#using_dpdt_relays

I wanted to use the ULN2803 Relay Driver Chip because its simple to use and cheap.

You can use a transistor and do it yourself (like explained on Geofex: http://www.geofex.com/Article_Folders/rmtswtch/rmtsw.htm) but why do it the hard way? :wink:

You can use 5V or 12V types. Both will work as long if you have the power supply for it. I choose 5V types because the whole MidiBox runs on 5V.

If you want to discuss that project please go to:

<___base_url___>/index.php?/topic/10910-guitar-fx-switcher-with-midibox/page__hl__fx%20looper&do=embed

Regards,

flo

5

Hey Flo. That sounds like a plan. I will order a Core unit today but, when you say I only need one DOUT, you’re saying i’ll only need 1/4th of the DOUTx4 unit, correct? That would make sense as each 74HC595 can control 8 relays, correct? That being said, I could vectorboard that easily and be on my way. Could use some part numbers for an appropiate relay. I normally order stuff like this from Mouser so, if you know of an appropiate part number, I would appreciate it.

Allrighty then, I think it’s time I get right into it, blow up a few chips and see how far I get. :slight_smile: I will continue this on the FX Looper thread. See you there.

6

See:

<___base_url___>/index.php?/topic/10910-guitar-fx-switcher-with-midibox/page__view__findpost__p__126526&do=embed