question about the FM

[ladybug]

hi...

i m about to purchase a set of the chips that Airmailed bulk-ordered, but wanted to know some things :

- will this FM synth have stages?? as the SID have A B and C... will i have the option to build it first with no controls/display at all (step A) and than add some pots (step B) and after go for the full interface (step C) ?

- is one set sufficient ?? or should i take 2 sets ?? is it same idea as the SID ??

- is it such a problem to desolder ?? why not just "bake" the Soundblaster untill the chips fall off ??

THANX

(off topic : please see my post on the Miscellaneous board = "in search of a FM STEREO transmitter" )

[Davo]

- is it such a problem to desolder ?? why not just "bake" the Soundblaster untill the chips fall off ??

I don't reccomend it.

1)  Any oven you use will be permanently contaminated by solder and flux fumes.

2)  The surface tension of surface-mount solder is very high.  This allows parts to be attached to both sides of the board without risk of parts falling off.

3)  It's very difficult to regulate an oven's temperature the way you need to for surface-mount work.  There are ways around that, but deal with mounting parts rather than removing them.

4)  Simply laying desoldering wick over the connection and pressing with a hot iron has always worked for me.

[shed]

From what I can read 1 set will be fine for the synth that tk has built with 4 audio channels

[TK.]

Hi rasOfir,

- will this FM synth have stages?? as the SID have A B and C... will i have the option to build it first with no controls/display at all (step A) and than add some pots (step B) and after go for the full interface (step C) ?

there won't be explicit steps - but of course, you can build the synth step by step in a similar manner like MIDIbox SID.

It's only important to know about the strict hardware requirements. I won't support the same flexibility like for MIDIbox SID - the higher complexity requires a large display, 8 soft buttons, etc...

MIDIbox FM will already run with a single MBHP_CORE and MBHP_OPL3 board + at least one BankStick. In this case all parameters have to be controlled via SysEx (-> JSynthLib). Most of them can also be controlled via CC

"CS Step A": requires one DINX4, one DOUTX4, a 2x40 LCD, 8 "soft button", one ESC button, one shortcut button, 4 INSTR/OP buttons, one INSTR/OP select button, 10 LEDs and one detented rotary encoder

"CS Step B": requires 10 selection matrix buttons + 24 LEDs + 4 rotary encoders

and thats all, you will have a complete MIDIbox FM

Best Regards, Thorsten.

P.S.: all schematics and interconnection diagramms are already published

[airmailed]

hi thorsten..

would you say a little about how you wired up the led matrix? (i looked at the photo but it wasn't totally clear to me from that).. it looks to me like a wire soldered to each led in the row.. is it as simple as that?

i had been thinking of other ways to do this since seeing the sid photos.. i wondered about using stripboard (with the anode or cathode poked into each row..) thinking about it now, it seems like this method would need 2 layers of board.. or stripboard cut into very fine strips ;-)

best wishes

adam

[TK.]

Hi,

yes, the wiring of the LEDs is very simple when you are *not* using a stripboard. I took 4 long blank cables for the cathodes (in a row), and 6 shorter blank cables for the anodes (in a column). These cables are directly connected to the DOUT module. Since the LEDs are clued into the panel and sitting very stable, the danger for shorts is very low.

The clueing and wiring was a job of about 1..2 hours

Best Regards, Thorsten.

[airmailed]

thanks Thorsten..

and thanks for creating the step b option without the matrix like i asked

best wishes

adam

[Julian]

i've got a question as well...

as FM synthesis doesn't include filters i thought about adding an gate out to the MBFM.

Wouldn't it be possible to make one (or 4) pins on the dout module to send a signal whenever a voice plays a note?

then you could use a simple circuit to make a standard gate signal out of it to control external ADSRs thus giving you the power of FM synthesis combined with smooth analog filters without the need for an expensive AOUt module...

best,

julian

[TK.]

Hi Julian,

8 AOUTs and 8 gates are planned

Best Regards, Thorsten,

(P.S.: the user manual is finished: http://www.ucapps.de/midibox_fm_manual.html)

[Echopraxia]

Big bump here

the wiring of the LEDs is very simple when you are *not* using a stripboard. I took 4 long blank cables for the cathodes (in a row), and 6 shorter blank cables for the anodes (in a column). These cables are directly connected to the DOUT module. Since the LEDs are clued into the panel and sitting very stable, the danger for shorts is very low.

The clueing and wiring was a job of about 1..2 hours

TK,

Looking at your picture of the led matrix it looks like the row (left to right) has its wire touching the panel and the column (up and down) are raised from the panel. Is it ok to run your leads touching the panel or am i not see correctly?  Are they both elevated from the panel? Did you use cut resistor leads or whats the trick?

Regards,

echo