MBCV v2.01 alternative concept

[latigid on]

We've seen the for the time being there aren't any working examples. The LRE8x2 boards are unfortunately not readily available, and there are a few issues with getting components mounted (GLCDs) and at the correct height. 

 

I would like to propose an alternative front panel, here are some rough concepts below. The window size is the previous idea, with the frame representing a smaller PCB.

 

 

 

Some differences:

1. Smaller PCB. This should fit in a 3U case, just like the SEQ v4

2. Illuminated encoders in place of LED rings. Different encoder layout

3. GLCDs mounted above SCS and accessed with the same buttons

4. All DIN(/DOUT) on board. Optional open collector buffers (7407) or other level shifters to allow for higher voltage gate/clock signals.

 

 

 

Illuminated encoders would be something new for MIDIbox. These would consume less power and DOUT pins, and require only one hole per encoder. Metal panels would be an option. I would have to check the illumination and quality before committing to a design. Two methods of controlling them are either special PWM code through a DOUT (about 4 levels per colour) or a dedicated PCA9635 (or other) driver running off the I2C buss (256 levels per colour). TK notes that the update rate would be slower with the second option, although the PWM clock is 1 MHz. Encoder types could be RGB or RG, this is something to discuss.

 

With a custom PCB we can have a purpose-built front panel, so I welcome proposals for encoder and button layout. People familiar with MBCV should note what the most important/useful functions are and we can go from there.

Edited July 21, 2015 by latigid on

[latigid on]

Note: I've just re-remembered sneakthief's MBCV enclosure in the other thread. It would be good to know if the button layout is optimal. My plan is to use encoders with push buttons, so there's a few extra degrees of freedom.

[Shuriken]

I think that FantomXR is working on a solution for the ledrings without the use of the LRE8x2 boards:

Edited July 21, 2015 by Shuriken

[latigid on]

Hi, yes I've seen this, many thanks. I will probably develop a single PCB version at least for my own needs, but community feedback is always welcome :)

[latigid on]

Why not go for the maximum PCB size?

 

 

A bit more symmetrical this way.

Edited July 21, 2015 by latigid on

[latigid on]

Okay, I've thought about a new MBCV v2 implementation after a chat with TK. and some time on my train journeys. I've followed the Lemur templates and here is what I've come up with. We don't have a panel or PCB yet so all assignments are flexible! But as I imagine multiple pages I've tried to group similar functions.

 

Here with channel 1 selected, the encoders adjust the amount of each modulator applied to it. Bipolar control could be quite interesting!

 

 

 

The right hand column of encoders is kind of a "meta mod." Instead of these fixed assignments (as currently in the Lemur concept) two modulators could be applied for each of of LFOA/LFOB/ENVA/ENVB and sent to any destination on the MBCV. This is a bit redundant considering the actual MOD section, but could free MOD up for interesting combinations, also for AIN control. Easier to label this way!

 

 

 

+ destination?

 

The aim would be to build a new control surface for MBCV without LED rings but using illuminated encoders as supported by TK. This way the PCB routing is simpler with less DOUT pins and less space/holes are required on the panel.

The layout has:

• Left hand buttons for selecting CV channel, and choosing the section (CONFIG, LFO, ENV, MOD, SEQ). I discussed with Thorsten about different "banks" and "scenes" although I'm not yet sure how these are implemented. Would a scene be like a preset of CV assignments?
• 4x OLEDs for scopes
• SCS (standard control surface of LCD, encoder and 6 buttons)
• Dedicated octave/fine tuning
• Chromatic keyboard layout for transpose and SEQ programming, with some dual purpose buttons
• Bank of 4x4 encoders which change parameters depending on which modulator is selected

 

As far as I can tell there are two possible uses of MBCV, either as a MIDI to CV converter or as a crazy LFO/ENV/SEQ source for a modular synth. Here are some possible architectures:

• 8 channel mono: 8(VCO; Gate), so 8 monophonic synths. Probably the best option as a modulation box. Could also operate as 8 voices on one channel, but I think few synths would use this
• 4 channel: 4(VCO, VCA; Gate, Trig). This could be controlled over 4 separate channels or 1 channel of 4 voices. (Trig is a short pulse sent at note on.)
• 2 channel: 2(VCO, VCA, VCF, MOD; Gate, Trig, Retrig, /Trig). Again two separate monophonic channels or one duophonic. (Retrig is a second pulse sent after a fixed delay time or using another threshold such as aftertouch or a modulator. /Trig sends a pulse when a note is released.)

 

Anyway, those are my thoughts without too much consideration into what's possible on the programming side :). Please feel free to add ideas or critique.

 

 

Edited October 9, 2015 by latigid on

[Rowan]

Im sure you guys have already thought about this...... But, will this design be eurorack friendly? i.e. Fit in a 3U rack?

[latigid on]

Im sure you guys have already thought about this...... But, will this design be eurorack friendly? i.e. Fit in a 3U rack?

I'm aiming for 3U, although I don't have definite PCB dimensions yet. Not quite sure if it will go between a pair of rails. The next question is: should it? The older idea with lots of LED rings consumes about 700mA if I remember correctly. And it would be around a whole block of 86 HP. But the IO is flexible. Either you can use the line drivers and connect up a breakout panel in the rack or else put your jacks/bananas/whatever on the box itself. As I've mentioned before my plan is to enclose a SEQ and CV in some sort of 19" case with a breakout panel and a decent PSU.

[Rowan]

The next question is: should it? 

Of course it should!

We both know if it fits a eurorack the number of people interested in the project will increase by an order of magnitude.

 

[TK.]

Please note: LFOA, LFOB, ENVA, ENVB, MODA..D are actually called LFO1, LFO2, ENV1, ENV2, MOD1..4, please change the graphics accordingly to avoid confusion.

From my point of view, the encoder assignments are too much channel-related.

I would prefer the configuration 2(VCO, VCA, VCF, MOD; Gate, Trig, Retrig, /Trig) with encoder assignments which change the most important parameters of an "instrument", such as:

CV1: VCO1 Pitch
CV2: VCA1 Amplitude
CV3: VCF1 CutOff
CV4: Aux1
CV5: VCO2 Pitch
CV6: VCA2 Amplitude
CV7: VCF2 CutOff
CV8: Aux2

And the default encoder assignments could be:
ENC1: CV1 Octave
ENC2: CV1 Semitone
ENC3: CV1 Finetune
ENC4: CV1 Portamento
ENC5: CV2 LFO1 Depth
ENC6: CV2 LFO2 Depth
ENC7: CV2 ENV1 Depth
ENC8: CV2 ENV2 Depth
ENC9: CV3 LFO1 Depth
ENC10: CV3 LFO2 Depth
ENC11: CV3 ENV1 Depth
ENC12: CV3 ENV2 Depth
ENC13: CV3 Value (Changes Octave/Semitone/Finetune)
ENC14: CV4 Value (Changes Octave/Semitone/Finetune)
ENC15: CV4 MOD1 Depth
ENC16: CV4 MOD2 Depth

I don't see the need to configure the MOD parameters with the 4x4 encoder matrix, it's much easier to change them from the appr. configuration page.

Same for the ARP and SEQ configuration.

Best Regards, Thorsten.

[latigid on]

 

Please note: LFOA, LFOB, ENVA, ENVB, MODA..D are actually called LFO1, LFO2, ENV1, ENV2, MOD1..4, please change the graphics accordingly to avoid confusion.

I think it will be simpler to identify modulators this way. I.e. Channel 1 LFOA = LFO1A, Channel 5 MOD C = MOD5C. Then the MOD is easy to assign across Channels.

From my point of view, the encoder assignments are too much channel-related.

Can you explain what you mean by this? I'm thinking about the following structure hierarchy, sorry if the pictures weren't clear:

Choose a channel. Here on one page you can adjust all 8 modulators, activate the sequencer and apply velocity/aftertouch.
Click "Config" and you have a second page of options.
Bank+channel number will select each ENV, LFO, MOD and SEQ, some have two pages switched by Config such as the 16 steps of ENV2/B and SEQ. To me this is the most intuitive way to access all parameters of a modulator.

 

I would prefer the configuration 2(VCO, VCA, VCF, MOD; Gate, Trig, Retrig, /Trig) with encoder assignments which change the most important parameters of an "instrument", such as

I think a more flexible approach would allow 2, 4 or 8 voices. Especially in a modular setup the concept of 8 CVs is very powerful, going beyond just a MIDI to CV converter.

 

And the default encoder assignments could be:
ENC1: CV1 Octave
ENC2: CV1 Semitone
ENC3: CV1 Finetune
ENC4: CV1 Portamento
ENC5: CV2 LFO1 Depth
ENC6: CV2 LFO2 Depth
ENC7: CV2 ENV1 Depth
ENC8: CV2 ENV2 Depth
ENC9: CV3 LFO1 Depth
ENC10: CV3 LFO2 Depth
ENC11: CV3 ENV1 Depth
ENC12: CV3 ENV2 Depth
ENC13: CV3 Value (Changes Octave/Semitone/Finetune)
ENC14: CV4 Value (Changes Octave/Semitone/Finetune)
ENC15: CV4 MOD1 Depth
ENC16: CV4 MOD2 Depth

ENC1-3: not required as there is a dedicated octave/fine encoder + a chromatic keyboard for semitone transpose

ENC5-16: for the most flexibility I suggest all modulators of a channel are accessible on one "bank" 

Same for the ARP and SEQ configuration.

Is it not better to have all 16 steps on their own encoders?

 

Edited October 11, 2015 by latigid on
Pictures appeared?

[latigid on]

Don't know what happened, so I'll put the pictures back in here:

[TK.]

I think it will be simpler to identify modulators this way. I.e. Channel 1 LFOA = LFO1A, Channel 5 MOD C = MOD5C. Then the MOD is easy to assign across Channels.

This kind of enumeration is legacy (e.g. same is used in MBSID and MBFM), please don't enforce a change (I won't do it anyhow ;-)

Whenever a value is changed, the related CV1..8 channel + the parameter name is print on screen. No need to think about a different approach.

 Can you explain what you mean by this? I'm thinking about the following structure hierarchy, sorry if the pictures weren't clear:

Choose a channel. Here on one page you can adjust all 8 modulators, activate the sequencer and apply velocity/aftertouch.
Click "Config" and you have a second page of options.
Bank+channel number will select each ENV, LFO, MOD and SEQ, some have two pages switched by Config such as the 16 steps of ENV2/B and SEQ. To me this is the most intuitive way to access all parameters of a modulator.

this won't work in live situations, where you want to have immediate access to parameter splitted over different channels

Your idea actually goes into a direction from where I wanted to get rid of.
The purpose of the 4x4 encoder field shouldn't be to replicate that what can already be configured with the menu interface.
Instead they should give you direct access to all parameters that you want to tweak live while playing sounds w/o switching banks or channels.

I think a more flexible approach would allow 2, 4 or 8 voices. Especially in a modular setup the concept of 8 CVs is very powerful, going beyond just a MIDI to CV converter.

Actually the firmware is constructed for 8 voices which work independent from each other.
The idea is to customize the access to voice parameters in order to simplify the usage - the frontpanel design should consider this.
 

ENC1-3: not required as there is a dedicated octave/fine encoder + a chromatic keyboard for semitone transpose

ENC5-16: for the most flexibility I suggest all modulators of a channel are accessible on one "bank" 

I think the biggest problem is, that you want to customize your MBCV for 8 voice usage and quick access to all configuration parameters.
And that I'm looking for something different, tailored around my own use case.

I fear that I've to create an alternative frontpanel design for my own usecase... :-/

 Is it not better to have all 16 steps on their own encoders?

That's ok, but the second layer which allows to change SEQ configuration parameters isn't necessary.
It's much easier to change these parameters from the menu interface, nobody will use the 4x4 encoder field for this purpose.

Best Regards, Thorsten. 

Edited October 11, 2015 by TK.

[latigid on]

I fear that I've to create an alternative frontpanel design for my own usecase... :-/

If we can agree on the hardware there's no reason why two different front panels couldn't be created. My approach places editable parameters for each modulator on its own encoder bank, on a per channel basis. It also needs a paging key for a second set of controls on the 4x4 encoders. Note your proposed encoder assignments do not include rate controls for the LFOs, A/D/S/R for the envelopes etc. -- how would you adjust these parameters?

[TK.]

Note your proposed encoder assignments do not include rate controls for the LFOs, A/D/S/R for the envelopes etc. -- how would you adjust these parameters?

Whenever the LFOx or ENVx depth is changed, or the LFO1/LFO2/ENV1/ENV2 button is pushed, the appr. menu page will be selected which then allows to edit the remaining parameters.
If somebody prefers to control a certain parameter directly, e.g. LFOx rate or ENVx decay, he has to change the encoder assignments.

I think that at the end we might be able to use the same frontpanel, but labels need to be customized based on personal preferences.

Best Regards, Thorsten.

[latigid on]

I see we are coming from different points of view: menu-based vs. knob-per-function. I know that I prefer the latter approach, for instance the sammichFM is a great compact synth but editing parameters on a 2x20 LCD and one encoder is quite unergonomic for me. I can see how having only depth controls makes panel labelling easier, but I prefer full access using the encoders (albeit requiring ninja skills to learn where each parameter is positioned). Selecting each channel one at a time and the configuration of its LFOs, ENVs, SEQ (also amounts from MIDI data such as velocity, AT, CC) etc. is also my preferred workflow.

For example, I would see that Channel 5 is active from its illuminated button, so I would know the encoder banks adjust the modulators' depths for this Channel. To change parameters for ENV5B (using my nomenclature) I press the left hand buttons "B+2" which shifts the encoder bank to ENV control. LFO5A = "B+3." These could be indicated with multicolour LEDs e.g. Channel Selected = green, "Bank" Selected (in my concept one of CONFIG, ENV, LFO etc.) = blue, and if the Channel and Bank numbers happen to match you will get cyan.

So you do have some multipurpose buttons, but thinking on the idea for a while this is the best "full control" solution IMO.

 

 

I think that at the end we might be able to use the same frontpanel, but labels need to be customized based on personal preferences.

I agree, there could be one PCB/PCB set with different faceplates depending on your preference :). Buttons/encoders could also be left out for instance if you didn't want a dedicated tuning control.

[TK.]

The sammichFM is maybe a bad example, because the user interface doesn't allow to select the pages directly (like for example a MIDIBox SID (not sammichSID).

However, it makes sense to collect opinions from future users.

It should be possible to implement different CS approaches for the same hardware, just the frontpanel silkscreen will be different.

Best Regards, Thorsten.

Edited October 11, 2015 by TK.

[latigid on]

Any further thoughts? Is the concept workable/what people want in MIDIbox CV?

I think at this stage it will be a good idea to create several small PCBs, that way the component heights are not so critical and it's more flexible (can even be used in other MIDIbox projects). I've also looked at getting RGB tact switches. 

The tricky part is still the OLEDs, I want to get them very close together which is difficult with the breakout boards. More expensive too. Soldering the 0.7mm ribbon is known to be troublesome but I'll try to find a way.

[latigid on]

Suggested spacing for the 4x4 encoder bank: 30mm horizontal 25.33mm vertical. This should fit on a 100x120mm PCB (3U friendly). Or is it a bit tight?

[TK.]

Similar spacing like on the MBSID panel, this should work

Best Regards, Thorsten.

[docljunior]

Hello you guys!

I've read your posts with great interest and I do have some thoughts.

1. It should fit in a 3u Eurorack.
2. I agree with TK concerning encoder behaviour and layout - touch an encoder and the apropriate menu page pops up. Works like a charm on Audiothingies P6 and Shruthi XT (wich is more similar - dedicated buttons for instant access and the value displayed + a clean user interface with a few buttons and encoders for navigation etc). Changing several layers that alters the behaviour of all the encoders can be very confusing - like the LXR or even worse the desktop Evolver. Although I do see the need for layers in order to implement all theese features.
3. Same front panel and pcb for whatever use you have. Custom labeling/screening.

Anyway. Good work both of you ;)

The only MB-project I have built is the SeqV4l and that is four years ago. I'm currently in the process of building a two or pherhaps three story 19" desktop eurorack case and I have been searching for a decent and flexible sequencer to put in it - so I obviously had to check in to see what was going on over here :)

Here's a (very) raw and unfinished sketch...

 

Finally I must say that I really find the v2 concept interesting and just perfect for my setup.

Best regards

Kolbjørn

Edited December 8, 2015 by docljunior

[latigid on]

Thanks for your input!

The next step will be to design and build the PCBs. I'm experimenting with colour as a means of easily recognising parameter groups

provisional, some things have changed already

[latigid on]

 

Okay, here's the three boards routed up:

4*4 matrix using WS2812s and Sparkfun button pads
CS board with 29 buttons, 4 OLEDs, space for a CLCD (more likely a 2*20 OLED) and 4 encoders -- with push switches or WS2812 depending on the configuration.
-- it's even symmetrical = lefty friendly!
4*4 encoder bank, also illuminated

It should be possible to use common DIN/DOUT boards, but to make things simpler I've made another board with 6 DIN, 4 DOUT and 2*5 headers which line up with the ribbon connectors. It mounts on the back of the CS PCB and saves two ribbons to the CS. Also included are level shifters for the DOUT gates and clocks using 2981 source drivers. Thanks @tashikoma for the tests re: current limiting using 1k resistors! If 5V gates are okay it will be possible to omit these chips and instead span a resistor over the relevant pads. 

It is a strange mix of DIP and SOIC, but all attempts to use regular 6-pin resistor networks for DIN pull ups were very tight and had inflexible PCB routing. I chose to keep the 595s through hole as these will interface with modulars and could be blown up! I hope this is okay, but if you're adverse to SMT it will still be possible to use smashTV boards. 

 

Another thing to note: assuming the concept works well enough these could be suitable for standalone NG builds or even MBProgramma . There's a thought of another PCB to mount the 45 degree displays on top of the encoders.

 

China is closed for their New Year, so I will mull over the design for a few weeks before fabrication. If there's any suggestions, please let me know.

 

[tashikoma]

YEAH!!! AWESOME
nice job!

YOU ROCK!

[latigid on]

Mechanical fits are good :)

 

 

Next up is getting the switch matrices working properly, deciding on the button assignments and thinking about colour coding.

 

This one's already in the RGB hue sweep thread, but I'll post it again for posterity: