Uploaded by MICHhimself on Jul 5, 2011
Yet another FPGA MIDI synth video, indeed!
My recent work on it was to enable it to play multiple voices at once, to make it polyphonic. I've converted the digital design so the digital audio is ouput through PWM, which only requires one wire per audio stream. This way, I can have 8 audio outs with just 8 wires.
The breadboard basically holds 8 low pass filters, which filter out the high frequency component of the outputs, and create a resulting analog voltage. Also on the breadboard is a typical summing circuit around a 741 operation amplifier. I need to tweak it a little bit, namely try some other resistor values, because it tends to distort a bit when using more than 3 voices, as you can probably hear.
More work is left to be done on the new Midi interpretation part of the digital design, since it tends to miss some key releases, which results in unwanted sustained notes. (You can see me pressing a button here and there; that's the reset button which sets all the voices back to the default status, and thus quiets down any playing notes).
Some more information: Since we're now using PWM, the previous 8 bit DAC is no longer required. That DAC was also connected up to an audio amplifier and the vintage speaker you could see in my previous two synth videos. Now I've replaced that amp + speaker with a 3.5mm jack plug which is connected to my speakers.
Uploader Comments (MICHhimself)
All Comments (9)
-
This is so cool. I wanna hear some other MiDi files played through this thing.
I'd love to have one as a kit. Seriously. I do MiDi stuff ALL the time.
-
K'NEXT! <3
-
Cool! I so much have to try this some day :P
-
Hot butter tag <3
-
that is epic
-
sounds great
-
congrats, it kind of sounds like a real synth now
19 videosYouTube Mix for Hot Butter- 3:55
Hot Butter - Popcorn 8 bit versionby HYP3R33725,277 views
- 2:36
Hot Butter Popcorn - 8-bit versionby SnydermanMusic927 views
- 1:45
Spartan 3 Simon Game Implementationby davidjtn1,731 views
- 0:41
Airbourne AVS04 Modular Synthesizer (FPGA based) Part 1/2by Moogulator1,331 views
- 2:34
FPGA MIDI synth demonstrationby MICHhimself1,275 views
- 9:47
Sound Lab ULTIMATEby theraywilsonshow20,478 views
- 4:10
Korg 05R/W Return to the Red Planetby robinj51,652 views
- 3:13
Scavenger - Reader's Digest (YM2149 ATARI ST)by 8bitbubsy1,204 views
- 4:18
Techno - Popcorn remix (best version)by havalito478381,444 views
- 2:39
Mc-202 tutorial #2: portamento, accents and accent modeby johnisfaster897 views
- 12:32
Home-made computer based on FPGA & ARMby MrLambdaUser7,161 views
- 0:56
Hot Butter - Popcorn (On Synthesizer, By: Wishful Thinking!)by ImPuLsE93483 views
- 5:17
Doepfer Dark Energy - The first try outby repeatle20,282 views
- 4:46
Judie Tzuke - We'll Go Dreamingby johnrabbit831,225 views
- 3:31
Wille and the Bandits - Chilloutby willeandthebandits2,631 views
- 3:03
waldorf microWAVE XT #01by a7soundlab64,204 views
- 2:48
Hot Butter - Popcorn (C64 SID Tune by BAT)by C64SIDTube1,062 views
- 8:21
PNW2008: Jim Patchell Demos the DSM1 FPGA synthesizerby matrixsynth1,290 views
- 4:12
FPGA Synth and Space Babyby WoosterAudio660 views
Sounds amazing :)
Is it too hard to output the sum of all channels through PWM?
NinoScript 7 months ago
@NinoScript Thanks!
It's the digital addition of the channels that poses problems. It may be due to the differing sample rates of different pitches, or just because I can't properly divide each channel's amplitude before adding them together, I'm not too sure. The way it's set up now provides an analogue addition, so I don't even have to sacrifice the resolution of the channels. :)
MICHhimself 7 months ago