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Is xoxbox receiving portamento?
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Is xoxbox receiving portamento?

by c_04 on Sun Jan 22, 2017 11:25 pm

Hi
I would like to build xoxbox but in rack enclosure working only in midi mode. Im courius that it can receive portamento CC via midi. I foud somewhere midi chart and there was stated that receives note on/off, probably 2 levels of velocity (accent) but no info abut additional CCs.
Cheers
Greg

c_04
 
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Re: Is xoxbox receiving portamento?

by antto on Mon Jan 23, 2017 1:38 pm

the x0xb0x is mainly a clone of the TB-303
it has "slide" but that's not exactly what most people would expect from portamento

in normal conditions, the 303 sequencer never causes the "slide" to be enabled at the beginning of a new note

you can get around this in a number of ways (via mods) and you can get the "slide" enabled at all times, which will be one step closer to what i'd call "portamento"
the simplest way i can think of is by cutting away the SLIDE control signal from the x0xb0x sequencer, and feeding 5V onwards to the rest of the circuit, which should be equivalent as if the sequencer itself is keeping the slide enabled all the time
(note: this would work in the x0xb0x but might not work on the 303, because the slide signal is also used for some extra things)

now, even if you enable the slide permanently - you will not be able to control the "portamento time" ... unless you mod that too

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Re: Is xoxbox receiving portamento?

by c_04 on Mon Jan 23, 2017 11:01 pm

Hi
Thanks for your reply.
Fortunately portamento called here slide is switched on/off by controlling processor. I know that portamento time cannot be changed (it can be modded to achieve that) but turning on/off could be also available via midi. And im asking about that. Slide mode also has another feature: when played constantly in sequencer mode: souds like one legato played note. I mean it should be like that. Also im not sure that xoxbox receives pitch bend control change. It could be similar effect to portamento/slide. When you open schematic, you can clearly see that processor sends to analog part - i could name it as "lines" which are: note pitch (DAC), accent, portamento and gate. So if this all works in sequencer mode why then not in midi mode? I do not need this entire part of sequencer - what i really want is 1U rack unit controlled via midi.
Cheers
Greg

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Re: Is xoxbox receiving portamento?

by rv0 on Tue Jan 24, 2017 9:46 am

Actually it does work in midi mode, but it's not portamento.

Your initial question asks for portamento, not slides.
Slides are possible with midi (overlap notes) but there's no "slide on/off" command. Same for accent, possible (through velocity) but no "accent on/off" command.
Of course you can mod the firmware to do this.

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Re: Is xoxbox receiving portamento?

by c_04 on Tue Jan 24, 2017 7:09 pm

Hi
And these are what i wanted to know.
Slide or glide or no matter how its called its always the same - portamento. When you open schematic there is a cap C35 220nf. And then if you open schematic for example of Korg MS10, you can clearly find the same circuit. In Korg also we can find how its made changable portamento time. Its simple - just put CV voltage thru variable resistor to capacitor.
In xoxbox portamento is turned on/off via 4066 switch and that complicate some things.
Anyway i just wanted to know what receives uC when in midi mode. Looks that not much.
Of course i could reprogram uC but i dont know how to programming. Maybe some day;)

So thank you very much. :)
Cheers
G

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