Searching for midi eq schematic

[Esppse]

Hello,

I was wondering if anyone successfully built an analog midi preset controlled EQ like the Payne labs MEQ. 5 bands or more is what Im looking to do. I've looked high and low for knowledge to get this done in a small pedal the size of the MXR 10 band eq. Can anyone help me with this?

Thanks!

[Redvers]

Not the answer you want but what's wrong with using a line6 M5?

[ElectricDruid]

Given the size of the Payne Labs unit, doing the same thing in a 1590B like the MXR 10-band is a bit of an ask!

It's probably doable, but you'd have to go SMD.

If I was approaching such a thing, I'd look for a simple graphic EQ circuit based on 10K, 50K, or 100K pots (since those are the values frequently available as digipots) and then I'd look at a PIC processor to read the control pots via the ADC inputs and set the levels of the various bands. Once that's in place, you've got a system you can add MIDI and programability to. You'd need a PIC with a UART (virtually all of them) and you'd need some EEPROM (either on the PIC, or external).

It's going to involve significant coding as well as a schematic. You'll need to program SPI or I2C comms with the digipots, you'll need to be able to do EEPROM long term storage, and you'll need to be able to decode MIDI messages coming from the UART. There's probably usable Arduino code for most of that that could be repurposed, but then it's unlikely to fit into your little box.

HTH,
Tom

[Esppse]

Ah thanks so much! You just made me realize it's impossible. I have no experience coding, it was just the last smallest spot in my rack system.

And I actually have the m5 as well, but was looking analog, I can always tell the difference.

[Esppse]

OHHH, better yet, is there a way to mod this to accept foot controller PC changes?

http://www.flexwaves.com/flex_eq7.html

Just stumbled on this, perfect size, it has presets programmable, and is analog, however no midi. I wonder how difficult it is to implement this option. Wow, they are all analog pedals with presets!

Would it be difficult to mod?

[ElectricDruid]

Depends what they're sending down that stereo cable to make the boxes talk to each other.

It might be really dumb, like just a switch-contact-close that indicates "move to next preset",in which case, you're stuffed. Or it might be something much more sophisticated, in which case you'd stand a chance, but it'd a be a pain to reverse-engineer their comms.

My best bet is that the presets are stored in each individual pedal and the most you can control from outside is which preset you're on. In which case, modding it isn't possible.

Tom

[Esppse]

OK thanks alot, midi seems like a very tricky thing to implement. I can see why many builders just stay analog. I appreciate the help#

[ElectricDruid]

OK thanks alot, midi seems like a very tricky thing to implement. I can see why many builders just stay analog. I appreciate the help#

MIDI might seem tricky to implement, but it really isn't. And often, you don't have to deal with all of it (for example, if you just want to send, or you just want to receive one particular message, like Program Changes or MIDI Clock).
It uses a UART which is about as basic as serial comms gets, and then it's at a really low rate, which means that you don't have to worry much about how you route it, and it's opto-isolated, which means you don't have to worry about ground loops. Honestly, it's as good as you get.
Builders stay analog because they're not programmers is all (or don't think they are, or have other things they'd rather learn). That's fair enough, but it doesn't say much about how easy or difficult MIDI is.

Tom

[PRR]

Tom, what is the minimum he'd need to get specific a single MIDI off/on code and work a relay?

[ElectricDruid]

Tom, what is the minimum he'd need to get specific a single MIDI off/on code and work a relay?

One PIC (could be an 8-pin chip - doesn't need to be massive) and an optoisolator for the MIDI input, like a 6N139. The hardware would look much like this:



If you don't mind driving your relay from MIDI "Start" and "Stop" messages, that'd probably do it (the "Running" output goes high when started, low when stopped). MIDI Realtime messages are about the most simple to handle because they're all single bytes and you don't have to worry about storing anything like you do with the multi-byte messages.

http://electricdruid.net/midi-clock-to-analog-gate-pulses/

What have you got in mind?

[PRR]

> What have you got in mind?

Another thread. Guy wants to program mike-mute with his MIDI which does settings for all his songs.

Your scheme is simple, but you do not sell the board or the programmed chip? This may be beyond his present skill-set.

As I understand, the mod would be this?


Let's continue on the mike-mute thread rather than drift this one.