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#61
Everything else / Re: Post your songs!
Last post by ToyKeeper - July 13, 2018, 04:56:17 AM
Much of the reason for the delay earlier is because I wanted to finish the song.  So earlier this week I decided to give it another try, using the Digitakt to do drums and MIDI sequencing.  This time things went much better.  The Atmegatron still helped make a nice dirty growling bassline, but I ended up using other instruments for the other parts because I only have one Atmegatron and it's all played realtime.

So here is "Easy Does It", finally finished:

https://youtu.be/9uHgZqewFFE

I would love to hear what people think of this.  It's my first attempt at making an actual song on a hardware sequencer, driving other synths in real time.
#62
Everything else / Re: Post your songs!
Last post by ToyKeeper - July 13, 2018, 04:51:04 AM
Quote from: rio on June 22, 2018, 11:39:26 PM
hey ToyKeeper,

after I could hear the songs in peace at home :D - here are some thoughts about it:

easy does it draft 1:
  these are really nice lead sounds and melodies that you created there. The recording sounds a bit overdriven, but maybe it was your intention. Personally, I think it would sound better, if not so distorted - especially in the bass area, there is a lot lost by that. You can certainly rasp at one point or another, otherwise thats quite passable... I would cut it a bit more. The combination of the bass melody with the lead sounds is really cool ...

digitest 1: is the arpeggio sound by atmegatron? it sounds nice melodic ... although the part is quite strong. the other sounds in the background are not bad either;)

...do not misunderstand me - I really like both tunes;)

Thanks for listening!  It really does mean a lot.  Also, sorry for the delay...

Let's see...  the main instrument in both songs is the "atmegabrute", which is two synths going through a delay effect.  The Atmegatron provides a chiptune sound, which is routed into a Microbrute as an external oscillator.  The Microbrute mixes this with a folded triangle wave, a PWM'd square wave, and an octave-lower sub-oscillator.  The mix goes through a variable resonant filter, then to a beat-matched delay effect.

To shape the sound, I only modified three parameters while recording:
* Atmegatron volume (from zero to massively overdriven)
* Sub-oscillator volume (from zero to massively overdriven)
* Filter base frequency (on mod wheel)

This provided three dimensions worth of expressive space to explore.  Most of it relied heavily on overdriven waveforms with the edge taken off by a filter...  because overdriven distorted basslines are what the Microbrute really excels at.  That's why all its knobs go up to 200%, and why it has a "brute factor" knob to feed the signal into itself.  I have the line in adjusted similarly, so the Atmegatron hits full volume a bit less than halfway up, and then gets distorted as I turn it up further.

As long as I'm using an intentionally-dirty analog subtractive synth, I'm making its spectrum very messy and cutting or emphasizing the relevant frequencies pretty heavily.
#63
miniAtmegatron / Re: Build problems. Fried boar...
Last post by paulsoulsby - July 05, 2018, 10:49:57 AM
Hi - what temperature did you have your soldering iron on?  As long as it wasn't on mega-hot mode, I'm sure the board will be fine.
R.e. the capacitor you replaced:  if the metal pads have been totally destroyed, you will need to use bits of wire to attach the cap to the traces.  Which cap was it that you replaced?
R.e. the LEDs.  Nearly all these pins are bridged!  I recommend buying some desoldering braid to remove the excess solder. There must not be any contact between the pads.
Also, there's no header in CONN4!  Don't forget to put this in - it won't work without it!
#64
ok thanks, for your great explanation...
#65
1) Yes these 3 are definitely logarithmic.  The others are linear
2) The codes are explained in the datasheet: https://www.mouser.co.uk/datasheet/2/54/tv09-777818.pdf
The 4 in "4225F" means that there is no sleeve to the pot, so it will wobble (some early units actually have this type, because I could not get stock of the other type)
The first 2 in "4225F"  means that there is a centre detent.  There isn't any need for a centre detent with any of the pots.  You use a detent when middle = 0 (but the Atmegatron only uses anti-clockwise = 0).
So technically and electrically PTV09A-4225F-B102 is fine, by you may find the differences annoying!

PTV09A-1025F-A203 will not fit the logarithmic pot holes.  They must be "dual gang" with 6 pins.

#66
ok, it looks like they are: "Cutoff", "Reso", "Filter LFO":



1. So can I use "Alps RK12L12C0A0E" as a replacement? - they have 15A taper -> they are logarithmic - Are you sure? I ask, because the 3 others are linear.

2. For the boost poti: I don't find Bourns PTV09A-1025F-B102  --> only PTV09A-4225F-B102 (can I take these as replacement therefor?)
they are linear, right?

PS: With that middle number 1025F, I can only find these "logarithmic" ones: "PTV09A-1025F-A203" <--- but these are not the right ones, right?

Please, I need more details about these both potentiometer types...

Greetings,
rio
#67
oh - no 3 of them are different.  You'll see they are bigger.  Here's the part:  Alps RK12L12C0A0E

The bass boost pot is 1k:  Bourns PTV09A-1025F-B102
Rest are 10 k.
#68
miniAtmegatron / Build problems. Fried board?
Last post by CatizenSnaps - July 03, 2018, 12:53:43 AM
Hello folks,

I recently sat down and put together a mini-Atmegatron kit and, upon completion, have found that it's completely functionless, won't power up at all. During the build, I had to desolder and refit one capacitor, and I fear I may have overheated and fried the board in the process - the metal circuit bit on the PCB peeled off slightly and I had a tough time getting the solder to stick again. I also had a little difficulty soldering the LEDs and I think I've bridged the three pins on one of them - I have a yet to correct this as I'm a little wary of desoldering following the prior problem. Is there anything I can do to try to fix it or is it likely that the board is irreparably damaged? If so, is there any way that I can purchase just a new board without the rest of the kit - the components and Arduino all seem fine. I've attached some pictures of the board for illustration. Still getting the hang of soldering and this is my first kit build, so please bear with me if this is more obvious than it seems. All feedback greatly appreciated!
#69
I think ALPS RK09D1130C2P should fit.

The 6 potentiometer at the top are all the same, right?
What are the "values/parameter" for the volume and boost potentiometers?

Greetings, rio
#70
ok thx.

greetings,
rio