Some questions about building a SeqV4

[jumpatron]

Hello everyone,

 

I’ve been looking into building a Midibox SeqV4. I’ve built some DIY synths in the past (the common ones) so I think I’m up to the task. Still, I’m a newbie in many areas so I have a few questions regarding building the thing:

 

To build a Midibox like the one shown on the main website I need to get these parts?:

 

PCBs:

• CoreLPC17 Module PCB (from Smash’s shop)

• SEQ CS PCB (from Smash’s shop once they are available)

• Quad IIc_MIDI PCB (from Smash’s shop)

 

Chips and microcontrollers:

• LPCXPRESSO (from embeddedartists)

• 4 x PIC16F88 (from Smash’s shop)

 

Basic parts:

Encoders, buttons from Digikey/Mouser/wherever

Resistors, LEDs etc. from Reichelt (or from Digikey/Mouser/wherever if it comes to same price (customs…))

2x LCDs (will any brand of LCD do?)

SD Card

 

 

To make things easier:

parts kit for CoreLPC17(from Smash’s shop) (long wait time?)

parts kit for Quad IIc_MIDI PCB(from Smash’s shop) (long wait time?)

 

 

Case:

Order one somewhere

 

 

The second thing regards customization. If I were a pro, I would want to build a SeqV4 with a small 2-octave xoxbox-style keyboard with LEDs that show which notes are being played in the current step. It would have octave up and down buttons (with leds indicating which one is active) + rest, slide and accent buttons + last and next step buttons. Although frankly just the keyboard with leds would be great. The keys would be the same buttons used everywhere else on the front panel, just turned vertically (I can paint the black ones white if they don’t sell white versions).

 

Of course the problem is I’m not a pro and I don’t know how I would go about making this, because I don’t know how to code or to make PCBs. So if it were a quick and easy task (probably not) I would ask someone on the forum to help me make this. If it’s not easy for someone to impliment then I’m happy to “just” make a basic SeqV4.

 

Thank you for your time.

[EsotericLabs]

Hello Jumpatron,

 

Yes you’ll need a CORE LPC17 and a LPCXPRESSO (plus parts of course). I would say a Quad IIC is optional, only if you really need the extra midi out ports. The Core LPC17 has two midi out connectors plus USB midi out. Any hd44780 compatible 40x2 LCD will work. Some eat more current than others though.

 

The control surface has three options:

a) wait for Smash TV SEQ CS PCB. This will surely work, but hardware customization will be more difficult - i guess

b) build a control surface yourself with cheaper standard buttons with straight wiring (see www.ucapps.de / seq v4 / manual / hardware options  / how many buttons - leds do I need /  check link to pinning diagrams).  For this you need 3x DINX4 and 1x DOUTX4.  You can add buttons and leds easily  (hardware wise) but you’ll need to go deep down in the code to add the functionality you want.

http://discourse.midibox.org/t/topic/14670

 

In any case, the butttons won’t work without code customization. I’m looking into code changes for extra buttons myself, but this will not be ready soon. 

 

Your sketch looks cool, for sure, but isn’t is easier to buy a small keyboard and hook it up? You will have velocity sensitivity, maybe extra buttons and sliders for control.  I guess this is difficult if not impossible with the CS buttons.

 

There is a midibox KB project and some people even found commercial keyboards with plenty of space for inbuilt midiboxes as well.

[latigid_on]

Hello, and welcome to the forum.

 

You have some good ideas for expansion of the SEQ concept but I am not sure exactly how you would go about implementing them.

 

The parts kit for the Quad IIC is not as extensive for the SEQ, and there is no waiting list for this or the SEQ PCB as far as I know. LCDs can range from cheap and generic to quite expensive; you should check the backlight polarity and interface type (Hitachi HD44780) before ordering.

 

It should be no trouble to build a simple control surface expansion on veroboard or even a custom PCB. There is a chain connection for additional shift registers on the main board which you can connect DIN and DOUT modules to in order to scan extra buttons or LEDs. Keep in mind that without (semi-complicated) matrix wiring the maximum number of inputs/outputs is 32 per module, you have 34 buttons in your design.

 

The panel could be easily remodelled for the extra functions. The case is always more work than the panel, it is worth trying to locate this part first.

 

The software side is where it gets tricky. I wouldn’t expect anyone (TK) to program these changes for you as it is a single use-case feature set. It is also unlikely that everything can be run on the same core module due to memory considerations; additional routines may affect the timing performance. In my opinion, your best bet would be to use a keyboard program running on a separate core, even an 8-bit one. Then you can forward the MIDI into the SEQ for note editing.

 

The SEQ does have a step-edit (303ish) mode, but I think what you are describing is a different application, and one which you would have to program yourself. The current interface is very powerful and there are many layers for accents and so on. Notes can be added with a standard MIDI keyboard.

 

It is great that you are thinking about something different and applicable to you, but if you say that this is your first project I suggest that you start with a basic SEQ build and see how that goes first. It would be possible to build an expansion later if you found the current interface too limiting.

 

 

 

 

 

 

 

 

[jumpatron]

Thank you for the replies.

 

I think I will need the Quad IIC, as I have many small synths I would like to control, so 6 MIDI outs would be very useful.

 

The SEQ PCB is currently sold out at Smash’s shop (production run in progress).

 

The main reason for having the xox keyboard on the SEQ is that it makes composition a lot easier, I find it distracting to look away when I’m “in the zone”. But I can see that the keyboard would be a bit difficult to impliment. I guess just having the LEDs showing the notes currently played would be enough (24 LEDs for two octaves, perhaps positioned above the LCDs), and that would be doable using a DIN and DOUT module? But again I don’t know if all this would require coding.

 

As for the case, aluminium panels look a bit expensive, although they obviously look and feel cool. But I’m scared I’ll screw something up and waste a bunch of money so it might be safer to get a lasercut acrylic case for my first SEQ.

[T.K]

Implementing the LED functions is actually a bit more difficult like the buttons, because the output routine has to differ between different layer modes and configurations.

 

I could help you on this, especially since with the 303 edit view the basics exist: http://www.ucapps.de/midibox_seq/cs4/edit16.gif

And I would be interested on a special HW extension for this purpose by myself

 

 

 

with a small 2-octave xoxbox-style keyboard with LEDs that show which notes are being played in the current step. It would have octave up and down buttons (with leds indicating which one is active) + rest, slide and accent buttons + last and next step buttons

 

What is “rest” in MBSEQ terminology?

(resp. what is a “rest” function?)

 

Best Regards, Thorsten.

[jumpatron]

Thorsten, that would be great! The 303-view actually is what made me think that it might possible to implement this. BTW I don’t have an urgent need to build a SEQ right now so if you are going to work on some of the features you certainly don’t need to rush on my behalf.

 

By “rest” I meant no note, empty note, skip note or whatever. Although I guess this could be accomplished by not entering a note and just pressing the “next” button. However I noticed that a “tie note” button is missing, and also my keyboard design appears to have invented a new note between B and C By getting rid of that note there is more room to space out the buttons (although there would be even more room if I moved the keyboard all the way to the right, but my brain demands that it be symmetrical with the big central encoder).

 

Here is a slightly updated design (including the perhaps redundant “rest” button):

 

[T.K]

Alright.

 

It makes sense that you wait for my version of this extension, because it could be that I will add some additional button functions which you would hardly miss in your layout…

 

To your functions:

Glide: ok

Accent: ok

Tie: is technically the same like Slide for a MIDI sequencer, therefore redundant

Rest: is called “Gate” in MBSEQ (with inverted function: note will be played when active)

The “last/next step” function (I would call it “Previous/Next step”) is redundant, because the datawheel and the Up/Down buttons have the same purpose. But it doesn’t hurt to duplicate them.

They are at a better reachable position for fast entry with the left hand, while notes are entered with the right hand.

 

I would order the functions differently:

 

Gate     Glide

Accent  Fx

Prev     Next

 

Fx: this will allow you to enable/disable the MIDI effects for certain steps.

Very useful especially in conjunction with MIDI Echo and Humanizer.

 

For the case that polyphonic steps are entered, additional indicators would be helpful to notify, that there are notes outside the displayed octave range. 

Duo-Colour LEDs for Octave Up/Down could be used for this.

And while writing about this: actually Duo-Colour LEDs also make sense for the keyboard so that “normal notes” are green, and “accented notes” are red.

 

Best Regards, Thorsten.

[jumpatron]

Thorsten, I like your style! I agree with everything you say.

 

 

Tie: is technically the same like Slide for a MIDI sequencer, therefore redundant

 

I had a feeling this might be the case.

 

Btw, how do you slide to the next step in a polyphonic sequence? Say you are playing three notes on one step and two notes on the next? Or say you play three notes on the first step (C D E) and three on the next (C# D# F), and want to slide:

 

1st         2nd

C     ->    F

D     ->    C#

E     ->    D#

 

Is that doable in the interface?

 

 

Accent: ok

 

How is accent defined in MBSEQ btw? Is it just 127 Velocity, or does it also affect filter envelope settings - in which case one would have to define the related CCs for each synth one is using (so basically a user-defined button)?

 

 

They are at a better reachable position for fast entry with the left hand, while notes are entered with the right hand.

 

This is what I imagined, too.

 

 

For the case that polyphonic steps are entered, additional indicators would be helpful to notify, that there are notes outside the displayed octave range. 

Duo-Colour LEDs for Octave Up/Down could be used for this.

And while writing about this: actually Duo-Colour LEDs also make sense for the keyboard so that “normal notes” are green, and “accented notes” are red.

 

Haha, I was thinking about these originally as well, but I thought I’d leave them out because the feature list was already getting long.

[latigid_on]

I’m interested in whether this is planned as a) an add-on for the SEQ (new box), b) an integrated solution in the same case, or c) an iPad/tablet controller. The latter would be neat as you could switch between this and the BLM. 

[jumpatron]

Another possible use for Duo-Colour LEDs:

 

Instead of showing accent (as accent is indicated by the accent button led, though it doesn’t show which notes) ,they could show octave. The keyboard could have two different duo-colour LEDs e.g. the lower octave Green/Red and higher octave Green/Blue.

 

So the keyboard shows e.g C3-C5. When you play a note below the range the LED colour is red. When you play a note above this range it shows up as a blue LED.

 

D2 = D3 key with red LED

D3 = D3 key with green LED

D4 = D4 key with green LED

D5 = D4 key with blue LED

 

So you end up with a keyboard that has a 4-octave range.

 

The problem with this approach is if you are playing several octaves of the same note. If you play D2 and D3 there would be no correct way to show this as they occupy the same key on the interface. Or three octaves of the same note. But I guess this is a problem with any approach.

[T.K]

Btw.: I noticed that MBSEQ calls the slide function glide (as you called it before)…  so let’s take this term.

 

 

 

Btw, how do you slide to the next step in a polyphonic sequence? Say you are playing three notes on one step and two notes on the next? Or say you play three notes on the first step (C D E) and three on the next (C# D# F), and want to slide:

 

1st         2nd

C     ->    F

D     ->    C#

E     ->    D#

 

Is that doable in the interface?

 

 

 

In order to get Glide working, your synth has to support the so called “SusKey” function (sometimes also called “Fingered Portamento”).

The synth will activate portamento whenever keys are overlapping.

For some synths (like MBSID V2 in Multi mode) this will also work correctly for polyphonic chords.

So: whenever Glide is activated, MBSEQ will play the new notes of a step, and then release the previously played notes to activate glide.

If Glide is not active, the length will be played according to the Length Layer (which could overlap as well, or also stretch notes over multiple steps)

 

 

How is accent defined in MBSEQ btw? Is it just 127 Velocity, or does it also affect filter envelope settings

 

It sets the velocity to 127.

All good synths (such as MBSID ;-)) allow you to assign various parameters to velocity.

E.g. MBSID in Bassline mode assigns not only the VCA sustain, but also Filter ENV Decay rate to velocity.

 

Using velocity assignments is the best way, because this ensures that the parameter is changed exactly at the same moment where a new note is played.

 

 

 - in which case one would have to define the related CCs for each synth one is using (so basically a user-defined button)?

 

You can assign one or more parameter layers to CCs to control this as well.

But in this case, you would have to set the CC values as usual in the EDIT page.

There is no relationship between the ACCENT trigger and CCs

 

@latigid on

 

I’m interested in whether this is planned as a) an add-on for the SEQ (new box), b) an integrated solution in the same case, or c) an iPad/tablet controller. The latter would be neat as you could switch between this and the BLM. 

 

Prototyping this extension on an iPad is a good idea!

 

Back to Jumpatron:

 

Instead of showing accent (as accent is indicated by the accent button led, though it doesn’t show which notes)

yes, you are right!

 

 

Another possible use for Duo-Colour LEDs:

 

Instead of showing accent (as accent is indicated by the accent button led, though it doesn’t show which notes) ,they could show octave. The keyboard could have two different duo-colour LEDs e.g. the lower octave Green/Red and higher octave Green/Blue.

 

Note that a Duo-Colour LED can only display green, red or yellow (mixed colour when both LEDs are active)

 

 

 

The problem with this approach is if you are playing several octaves of the same note. If you play D2 and D3 there would be no correct way to show this as they occupy the same key on the interface. Or three octaves of the same note. But I guess this is a problem with any approach.

 

How about following approach:

Red: one or more notes are played outside the displayed octave range, but not in the visible range

Green: one or more notes are played in the displayed octave range and not outside the range

Yellow: notes are played in multiple octave range (so, partly displayed, partly not displayed)

 

And then use color coding for the octave buttons as well.

It could make sense to spend 5 LEDs for the octave buttons for the 5 available octave ranges (they would span 120 notes).

This would allow to display the octave ranges, in which notes are played, with yellow colour.

And the green colour would display the selected octave

 

Speaking about number of LED/button functions (resp.: DIN/DOUT shift registers):

it definitely makes sense to connect the LEDs and Buttons in a matrix configuration.

With 1 DIN and 2 DOUTs, up to 64 buttons and 64 LEDs (Duo-LEDs: 32) could be accessed.

The MBHP_DIO_MATRIX module fits perfectly for this purpose.

 

For the current keyboard extension layout we would need 32 buttons.

32 inputs are currently free for additional button functions.

 

LEDs:

• 2*24 for the notes (Duo-Colour LEDs)

• 2*5 for octave selection (Duo-Colour LEDs)

• 4 for Gate/Glide/Accent/Fx

makes 62

 

Two LEDs are currently free for other purposes.

 

Best Regards, Thorsten.

[T.K]

The non-functional prototype for Lemur
 

 
How about dedicated octave buttons?

 

And two additional buttons/LEDs could be used to enable Recording or Live Playing mode.

 
Best Regards, Thorsten.

[SiliconHeaven]

O_o I must look away…but I can’t.

I’m in the same boat as Jumpatron, patiently awaiting CS PCB’s to arrive in SmashTV shop…but I think I better wait around to see how this develops.

@TK will you be posting the modded firmware in the future for others to attempt this as well? MBSEQ 4.1?

[latigid_on]

 

 

Is it possible to map an extra parameter on the y axis? :rolleyes:

[jumpatron]

Thanks for the clarifications regarding glide and accent.

 

How about following approach:

Red: one or more notes are played outside the displayed octave range, but not in the visible range

Green: one or more notes are played in the displayed octave range and not outside the range

Yellow: notes are played in multiple octave range (so, partly displayed, partly not displayed)

 

Sounds good.

 

 

And then use color coding for the octave buttons as well.

It could make sense to spend 5 LEDs for the octave buttons for the 5 available octave ranges (they would span 120 notes).

This would allow to display the octave ranges, in which notes are played, with yellow colour.

And the green colour would display the selected octave

 

That sounds sensible.

 

 

Regarding extra buttons:

 

• Would the octave buttons be hard to fit on the interface?

• A button to jump into 303 mode from whatever page/view you are in (and pressing it again jumps you back to where you were before, so you can easily switch between two pages). Or would live/record buttons serve the same function?

• Midi remote functions button? So you can use the keyboard buttons to launch patterns, input characters or whatever (maybe a feature for the “do later” pile)

 

Here’s a sketch with a few more buttons (octave buttons + live and record). The octave leds would probably make more sense in a horizontal line, e.g. under the central encoder, but it would be difficult to place any buttons near it without moving the keyboard down a lot (thereby making the the whole thing much bigger than it needs to be). So I’ve placed them on the side for the time being. I also coloured some of the LEDs, but they’re kinda hard to see.

 

 

[T.K]

• Would the octave buttons be hard to fit on the interface?

 

it seems that you found solutions. I like the third layout where the octave buttons are at the right side.

 

 

 

• A button to jump into 303 mode from whatever page/view you are in (and pressing it again jumps you back to where you were before, so you can easily switch between two pages).

 

it will be displayed when you push the EDIT button (and selected the 303 view)

There is no jump-back function, but in practice it isn’t really required (and could be confusing)

 

 

 

 

• Midi remote functions button? So you can use the keyboard buttons to launch patterns, input characters or whatever (maybe a feature for the “do later” pile)

 

I don’t find this really useful - it’s better to use the GP buttons under the LCD for this, so that you see what you are doing…

 

More ideas (e.g. also from other interested people)?

 

Best Regards, Thorsten.

[jumpatron]

it seems that you found solutions. I like the third layout where the octave buttons are at the right side.

 

I think this might the best layout of the ones presented, too. I imagine they are buttons that one would press quite often, so at the right they are easy to access and not in the way. In fact it might better than having them horizontally, because then you’re hand would be constantly blocking the keyboard when pressing them.

 

Oh and obviously the octaves will follow the buttons, with the highest octave keyboard at the top and the lowest at the bottom.

 

 

it will be displayed when you push the EDIT button (and selected the 303 view)

There is no jump-back function, but in practice it isn’t really required (and could be confusing

I don’t find this really useful - it’s better to use the GP buttons under the LCD for this, so that you see what you are doing…

 

I can see that my unfamiliarity with Midibox is showing. Still, I wonder if there are pages where the keyboard and its LEDs could provide some additional functions (arpeggiator, custom delays (e.g. if your delay repeats 8 times you’ll see 8 green LEDs on the keyboard, pressing a key turns the LED red and mutes that repeat, so you could have 6 repeats - mute - one repeat) or easy access to presets on certain pages)?

[ilmenator]

With the octave keys, is it really necessary to have a two-octave keyboard?

 

I am thinking of having this “module” sitting next to a TPD module, which is around 8cm wide and 9.5cm in height. Unless the keyboard is slightly “condensed”, having a two-octave keyboard might get a little too wide overall?

[T.K]

I can see that my unfamiliarity with Midibox is showing. Still, I wonder if there are pages where the keyboard and its LEDs could provide some additional functions (arpeggiator, custom delays (e.g. if your delay repeats 8 times you’ll see 8 green LEDs on the keyboard, pressing a key turns the LED red and mutes that repeat, so you could have 6 repeats - mute - one repeat) or easy access to presets on certain pages)?

 

It would be very difficult for me to provide fully customizable functions which allow to select preset parameters in a configuration file.

In MBSEQ V4 Lite we’ve this - but here I directly programmed this into the source code.

Of course, if you have programming skills, you could do the appr. modifications in the source code by yourself…

 

However, with the “Bookmarks” feature a semi-customisation is available. It doesn’t provide exactly the possibilities that you requested, but at least it could be useful for alternative keyboard assignments:

See also the end of this page: http://www.ucapps.de/midibox_seq_manual_m.html

 

 

 

With the octave keys, is it really necessary to have a two-octave keyboard?

 

I could provide a one-octave option.

I guess that you don’t want to add 10 octave buttons (and LEDs) in this case, so that the octave range would have to be reduced for such an option (e.g. only play notes between C-1 to B-5)

 

Best Regards, Thorsten.

[jumpatron]

Thanks for the answers.

 

The only thing I can still think of regards drums - will they show up on the keyboard LEDs?