MIDIBox Mixer - A PGAx311 Audio Mixer

[Orkspalter]

Ok heres my attempt to make my thought a bit more understandable;-)

....hmm...i haven´t thought about the whole impedance problem until now:-(

....by the way, this routing is just a quick way how to use the mixer as a guitar pedal router. If anyone does know a more clever resolution please share your thoughts. Of course the downside when doing this is, that all pedal in each channel will only be running in parallel and would not be able to feed into each other which is normally done if pedals are connected in series and are sitched on and off via true bypass.

Maybe it would be better to make the pedal channels full mixer channels, but that way i would need about 25 PGA chips and routing an effect channel via effect send straight to delay and reverb doesn´t make sense, as the effect pedal signal has to pass the preamps. Hmm....or doing an third effect send channel for all channel 1 to 12???

[Orkspalter]

Usage for my intends:

A total of 22 Guitar effect pedals (distortion, booster, compressor etc.)can be connected to the 12 channels, having one on each stereo side of each stereo channel. The volume can be adjusted of course by the PGA chip and via the panning function of each channel, L signal or R signal can be panned between the 2 guitar preamps, not complete control but making it kind of routable more to preamp 1 or more signal to preamp 2.

Feeding the signal back into the mixer i am able to add after-preamp effects, like modulation and time based, reverb, delay, phaser...which have to be placed AFTER the guitarpreamp. Via effects return 1 and 2 i am able to control how much effect signal is added to the untouched guitar amplifier signal, so a great way get rid of the downsides of digital effect processing

[lylehaze]

Cool. I get it now.

You are setting up all your effects pedals in parallel (side by side).

So your "input stage" from the guitar will be driving 20-odd different input channels.

Well, you'll have a better chance of doing that if you get to build it yourself, so you don't have to deal with 20-odd impedance resistors in parallel. That part should work.

What you will be missing is the chance to connect your effects in series. As I understand it, that's how it's usually done. "Clean" guitar goes into effect 1, effect 1 out goes to effect 2 in, etc..

I figured you could do something similar, with each effect output having a mix into the mains (at that point) and also 2 outputs into the "next" effect(s)..

That would be some kind of Pyramid thing..

Channel board 1 feeds into Left (clean), Right(clean), and the FX1 and FX2 outputs each feed clean into two different effects inputs.. Say, for example, a compressor and a reverb unit.

Each of those effects outputs(mono) can be mixed into Left, Right, and branches into Two more possible effects chains... Not every effect would HAVE to split wider, but the potential is there.

You would end up summing a wide variety of effects levels, from pure, clean from just the first channel board, to a endless combination of effects feeds..

All of this could be done by just removing the stackpins from the C and D mix outputs(FX1 and FX2) and wiring each boards FX outputs to other effects.

What you could NOT do is to re-arrange the order of the effects, they would stay in the same sequence unless you manually re-connect them.

Either way, it would be a lot of fun.

Discussion Please? I'm not a guitar player.. but it seems like it could get really diverse.

Have Fun,

LyleHaze

[lylehaze]

I have a GIF that I drew, not sure how to insert it in the forum..

already I have other ideas too.

LyleHaze

[Orkspalter]

Do you now understand my last EMAIL as i said, this drives my crazy as there are soooo many ways to configure it?!!:-D

Maybe Flo (Floris) should come up here as he has done an Effects Pedal Looper here on the forum. Flo were are you??!! :P

[lylehaze]

OK,I figured a way, with a bit of hardware wiring, to do this:

The first channel board has the guitar input pre, and it's outputs are Left and Right clean, and the FX outputs feed two possible effects chains. Simple enough.. Now it gets twisted..

Each of the additional channel boards serves one effect, using the FX1 and FX2 controls to mix the SEND (to the effect) between clean and the FX output of the previous stage.. the Left and Right outputs control the mix of the RETURN(from effect) to the audio mix. This effect return is also passed to the FX input of the next stage.

Because only the first channel board actually needs its input preamps, we have four "available" op-amps on each channel board unused. This hack will use one of those to combine the clean and FX input signals into the SEND for the effect.

Nice thing is, it will work with the existing "full mixer" software, no changes needed there. There will be a few jumper wires between the channel boards, but not too bad.

Controls will work something like this:

Channel 1 Level and pan are "clean" guitar into the mix. Channel 1 FX1 and FX2 allow playing with the starting levels of the two effects chains..

For each effects channel (2-16):

Main Level and pan will control mix from the return from that effect into the outputs (left and right) as you'd expect. FX1 and FX2 will allow you to select the balance of input, from "clean" on FX1 to the output of the previous effect with FX2. Instead of controlling outputs, these are actually mixing up the signal going out to the effect for this channel..(weird, but useful)

So, If you set all the effect channels main levels to Zero, Set all FX1 to zero, and turn up all FX2s, you'll get all your effects in series, one after the other. You WILL have a gain setting between each one, using FX2.(turn up main level on the last effect to hear the result)

If you turn off all the FX2s and turn on all the FX1s, then each effect will get a "clean" input, and you can control the input drive for each effect with FX1, and combine all the outputs using the main level controls.

But the best part is that you can combine and re-arrange the above, doing everything except re-order the effects chain. Not too bad. Now "play" with the settings live with a sequencer.. MIDI control rules!

I think this will be the most flexible option.

You should be able to remove one wire and handle stereo effects returns too.. as long as you don't need to swap left and right in software.. But we'd need to sum the stereo returns to create the feed to the next effect.

One possible problem, some effects have a inverting output, some are non-inverting. Combining their outputs might start cancelling each other out.. could sound weird. Easy enough to fix it, but that is another topic.

This could really kick ass.. I hope I have explained it well enough..

Thoughts??

LyleHaze

[stryd_one]

Every well worded question contains it's own answer:

This could really kick ass..

Thoughts??

'nuff said ;)

[matoz]

Hi Lylehaze, in the Wiki at MB Mixer description, you say "Circuit boards are available".

Where are they available?

[nILS]

Hi Lylehaze, in the Wiki at MB Mixer description, you say "Circuit boards are available".

Where are they available?

They _will_ be available.

[lylehaze]

Hi Lylehaze, in the Wiki at MB Mixer description, you say "Circuit boards are available".

Where are they available?

You are right. I have edited the wiki, and it now says:

The circuit board designs have been provided to SmashTV, and will be available in his web shop. If you are interested, please let him know!

I should probably include a link to his shop, but I'm kinda busy today, and I have little time to figure out how to add external links to the WIKI page. Maybe tonight if I get some free time.

I would like to add that Smash has cleaned up the design a bit, and added a LOT of time tracking down better parts for these than I used in the original. This is a great benefit to everyone that will be building with these. It's not a simple project, and some of the parts are unusual and hard to find.

Thanks for your interest,

LyleHaze

[matoz]

I already asked him at the beginning of year, I don't want to badger him…

I think Smash knows that a lot of people are interested by this project and they are waiting for boards availability.

Thanks

best regards

[nILS]

...I don't want to badger him…

Good move! ;)

[Orkspalter]

Lyle, i checked both types of channel meters, but it looks like the bargraph version won´t work with my display, numbers are fine. I still have to connect the digital input board with the encoder, i used the MIOS Studio Keyboard to change channels and volume/ PAN but can´t make program changes and test patches.

CIMG0965.JPG

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[Orkspalter]

Volume meters in numbers

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[Orkspalter]

Channel mute

CIMG0968.JPG

CIMG0968.JPG

[Orkspalter]

Bargraph

CIMG0962.JPG

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[Orkspalter]

Backlight stolen

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CIMG0955.JPG

[lylehaze]

Very nice..

I guessed that the meter code wouldn't work on most displays.. But the dB code from Pilo should work with everything.

It should be possible to define the special characters for the meter in software, but I got busy working on other parts of the project.

Lately I've been busy moving. Most of the furniture is already gone, and there is nothing at all left in my office. Now the audio rack with MBMixer and Amp are sitting in the living room along with a pair of 12" stage monitors, and are connected to the television. My wife is getting spoiled by the "Big Sound" we have for movies now. I may never get my stuff back for my office!

That also explains why I'm working on a remote control receiver with MIDI out, so I can adjust the volume without getting up from my chair.

Thanks for posting the pictures. Once the boards are available I hope we'll get a few more builders interested.

LyleHaze

[matoz]

"Once the boards are available I hope we'll get a few more builders interested."

Hi Lylehaze, don' t worry, i think these concept will make some noise in internet when boards will be available!! It is the first DIY midi controlled mixer and it has a lot of possibilities!!

I envisaged to build a 52 tracks mixer (6 mixers of 8 mono boards into one mixer of 8 stereo boards) , controlled by MB 64 (3* 16 midi tracks).

I think there will be more posts on this thread when we will have boards...

best regards

[lylehaze]

i think these concept will make some noise

I REALLY hope you are wrong. I went to great lengths to separate the digital and analog circuitry, and even mapped out four separate ground circuits when I designed the circuit boards, all to reduce noise to the lowest possible levels!

OK, so I know that's not the noise you meant. I'm just trying to be funny here.

I'm really proud of the work, it has taken a few years to get it just the way I want it.

I am a bit scared of how many different directions it might go in.  At first I thought Orkspalter was a bit crazy about using it for guitar effects, but now I see a way to do some really neat stuff with that. I'm even thinking of making a guitar effects hub myself, even though I sold my guitar two months ago.

I was asked about using it in a church, just because the presets are so easy to use. That's not a bad idea, even for animatronics shows like Chuck-E-Cheese, or theme parks. It makes audio control as easy as adding a MIDI port, and it's smaller than a board with motorized faders.

And I'm still wondering when "Home Automation" will take off. I expected that to be big business twenty years ago, and I'm still waiting. This would be a great start on the audio part of that.

I think the  biggest problem right now is that the software only goes up to 16 channels. That's really easy to get around, but I'm sticking with 16 because that's how many channels MIDI has. To do anything different would be moving away from the "standard". As it is now, you can plug a stock BCR or BCF deck into it and it just works. Same for whatever software mixing boards you might have.

Hey, maybe it'll get popular enough that someone will offer me a job! now THAT would be cool.

And I'm still adding "stuff" to it. I have an MP3 player and USB file access (see MBStor),

I am adding a remote control receiver to it now, just because I'm lazy. The remote will connect to the mixer by a regular MIDI  jack.

I'm kicking around the idea of supporting VU meters, even though that will mean adding a bit of hardware.

Once the VU meters are working, maybe a volume correction option (slow compression) for television channels that blast commercials... That would be all software.

Maybe tone controls too. That would add an extra 4311 for each channel board, but you'd get

a 4 band EQ for that channel.

Yeah, the ideas keep coming.

I'll shut up now.. Thanks for the interest! The future is getting closer every day..

LyleHaze

[matoz]

"I'll shut up now.."

you have said too much to excite my curiosity!

"Maybe tone controls too. That would add an extra 4311 for each channel board, but you'd get a 4 band EQ for that channel."

that is very a good idea!! do you prepare another board that could be connected to the other boards?

That board must be more expensive with an extra 4311 but I think it worth the cost easily and, of course, it would complete your concept seriously.

[lylehaze]

Adding a 4 band EQ is easy enough,  but the changes to the board would make it a "full mixer" only, so we would lose the ability to use that board as a stereo line mixer, as the EQ would be for a mono channel only.

That would make it less flexible, so not as good for the hobbyist bunch.

How far can it go? Way too far to be affordable.

If I was to design without care for cost, I'd have a channel strip with:

PGA2500 front end, including balanced / phantom power options

PGA4311 for 4 channel EQ

PGA4311 for 4 effects sends

PGA4311 for main and monitor stereo feeds.

VU metering of all levels (input, post-EQ, and each output) available in the DATA STREAM (no local LEDS)

local processor for control, networked by MIDI messages over CANBUS.

Funny enough, I'd want to keep the same channel board size, as it's still getting packed into a cabinet without much (or any) local controls. Can you imagine designing a control surface for a monster like that?

But, it's not really a great idea when you get too expensive. It would be over $75 per channel strip just for the big chips. by the time it all got added up, nobody could afford the damn thing.

Also, at SOME point, it's a better idea to go digital. But what I like about the way it is now is that the audio is all analog. Since that's a big part of what makes this special from other mixing boards, I'd hate to lose that.

SO we are back to where we are now. I made it as flexible as possible, and I get to wait and see how many different directions it goes in. The rest is all just dreaming. :-)

LyleHaze

[lylehaze]

The bargraph display option..

It's not that important, as the dB display is more accurate and it works with all display types.

But if you are looking for a display that will support the bargraph option also, I have found

the following at electronicsgoldmine.com: 2X20 Vacuum Fluorescent display. for about $25.

It is almost identical to the display I'm using, and includes the vertical bars from 0x10 to 0x18

It's a Noritake Itron, part number CU20029ECPB-W1J

I like VFD displays, but they do use a bit more power than the LCD types.

Have Fun,

LyleHaze

[matoz]

Hi LyleHaze,

Have you got some news, have you made more tests?

[lylehaze]

My personal life has been very busy, including moving twice in the past six weeks.

I am working ten hour days now, so I won't be online as much, BUT,

Smash and I were working a bit just last week on ways to make the project better.

It is still very much "alive", we have not forgotten it yet.

We just want to get it as good as we can for the very first version, so everyone

can be happy the first time around. :-)

It's not ready yet, but we are still getting closer.

LyleHaze