KVR Audio

justin3am · Post by **justin3am** » Thu Jul 24, 2014 6:50 am

Update 07/31: First sound example!
http://soundcloud.com/justin3am/ambika- ... -and-stuff

Update 08/07
http://soundcloud.com/justin3am/ambika-arp

Hey,

It's been a while since I posted here. I thought I might share a project I'm working on.

I just received the PCBs and electrical parts for an Ambika from Mutable Instruments. Ambika is a 6 voice poly-synth with digital oscillators and analog filters and VCAs. One of the many cool features of this synth is that there are different flavors of voice cards which can be used interchangeably. You can even use different types of voices cards at the same time. I'm building 6 of the SVF voice cards.

The voice allocation, preset system and global modulations are controlled by an ATMega644p and each voice has it's own ATMega328p for sound generation and per-voice modulations. The state variable filter is based around the Cool Audio version of the SSM 2164 quad VCA. It has a Low Pass, High Pass and Band Pass modes.

The first thing I do is check the packing slip from Mouser against the BOM to make sure that I have all the parts I need.

This took a while, but I'm glad I did because I quickly discovered that I didn't order enough 20MHz crystals for all of the voice boards.

Next I collected my tools and threw together a make-shift work bench (I don't have a permanent work space right now).

I started the build by populating the resistors on the motherboard.

I didn't have much time for assembly tonight so I only got through the resistors and diodes.

That's all for tonight. I'll try to post daily with my progress but I can't make any promises. I'm already having a lot of fun with this project.

Hink · Post by **Hink** » Thu Jul 24, 2014 11:20 pm

cool Justin

justin3am · Post by **justin3am** » Fri Jul 25, 2014 1:08 am

Thanks Hink!
For anyone interested, here are some sound demos of the Ambika.
http://soundcloud.com/mutable-instrumen ... nts-ambika

justin3am · Post by **justin3am** » Sat Jul 26, 2014 6:25 am

I fell asleep before I could post an update last night.

Yesterday I added the ceramic caps, IC sockets and shift register ICs.

justin3am · Post by **justin3am** » Sat Jul 26, 2014 6:41 am

Tonight I added the most of the remaining components to the motherboard. Voltage regulators, electrolytic caps, connectors, pots, switches and LEDs.

The only things left to install are the socketed ICs and the display. Before I do that, I have to test the power rails and make sure there aren't any shorts.

The +3.3v, +5v, +8v and -8v rails are all working!

I decided I don't like the green display that was listed in the BOM, so I'm going to order this one: 40 x 2 black and white display

When I get the new display, I'll install the socketed ICs and fire it up. Tomorrow, I'll start working on the first voice card.

Hink · Post by **Hink** » Sun Jul 27, 2014 3:15 am

a lot to populate

justin3am · Post by **justin3am** » Sun Jul 27, 2014 4:03 am

No kidding!

I finished building the first voice card today.

I have 5 more of these to go.

I couldn't resist installing the socketed ICs and checking if the voiced booted up.

Success!

Hink · Post by **Hink** » Sun Jul 27, 2014 4:18 am

Did the boards come with all the parts or did you have to order them from mouser?

justin3am · Post by **justin3am** » Sun Jul 27, 2014 4:26 am

I ordered most of the parts from Mouser. I had some of the more common parts on hand. Only the PCBs and acrylic case are available from the Mutable Instruments store.
He has really detailed BOMs with references to part numbers for a few different suppliers.
Here are links to the building instructions for the motherboard and the voice cards:
http://mutable-instruments.net/ambika/build/mobo
http://mutable-instruments.net/ambika/build/voicecards

The whole project is open source, so I could make my own PCBs if I were so inclined.

justin3am · Post by **justin3am** » Mon Jul 28, 2014 2:57 am

I finished two more voice cards today. I still need to add the 20MHz crystals, they are due to arrive on Tuesday.

3 more to go!

MWSOS · Post by **MWSOS** » Mon Jul 28, 2014 3:51 pm

Hi Justin!

Great project - I still LURVE my Shruthi with its SMR4 mkII filter board, which I've since heavily modified with a host of extra features (all the details are documented here if you're interested, along with some Soundcloud demos http://mutable-instruments.net/wiki/Shruthi-1_SDE

Good luck with your final voiceboards, and we look forward to hearing your polyphony in action soon

Martin

justin3am · Post by **justin3am** » Tue Jul 29, 2014 12:55 am

Hi Martin, thanks for stopping by!

Your Shruthi mods for the SMR-4 are really awesome. I've been tempted to build a Shruthi-1 for a long time (back when it was called Shruti-1) but I wasn't really in the market for a mono synth. I may have to build one now, just to experiment with all the cool mods.

I've been investigating the possibility of adding filter FM to the Ambika, but since it's not practical to add a individual pot for each voice so I've been trying to hack the firmware to make it work. Olivier says that the control rate for the filter is limited to 1kHz, after which aliasing kicks in but I'm not deterred.

I'm really intrigued by your Res CMP mod. If I build the SMR-4 voices for Ambika (which I probably will), I may experiment with that mod and add jumpers for the different settings (since this probably isn't something I'd want to change frequently).

I have some ideas for my own Ambika mods but they mostly involve firmware changes.

bftucker · Post by **bftucker** » Tue Jul 29, 2014 2:01 am

Justin3am: Thanks for posting these. You make it look easy. If I were to attempt something similar, where would I have the biggest problems in your obviously expert opinion?

justin3am · Post by **justin3am** » Tue Jul 29, 2014 6:46 am

My wife and I went out, so no progress tonight.

bftucker wrote:Justin3am: Thanks for posting these. You make it look easy. If I were to attempt something similar, where would I have the biggest problems in your obviously expert opinion?

Ha! I'm no expert, just and enthusiastic nerd. I solder 0603 surface mount parts at work, so this is pretty easy by comparison. All the parts are through-hole, the build instructions are incredibly detailed for such a big project and the engineer behind the project (Olivier Gillet) is very active on his forum.

If you are new to building, this probably isn't the project to start with. The voice cards are pretty dense, so a careful hand is necessary. It's not a kit, so you have to source your own parts. I think there are some saved 'carts' which include all the necessary parts, so you can click on a link and get all the parts at once. That said, a lot of parts I needed weren't in stock at just one place so I had to find them from other suppliers. If you don't get the V2164d chips from Mutable Instruments, they will be >$5 a piece.

You might want to look at the Shruthi-1 kits. The kits include all necessary parts.

justin3am · Post by **justin3am** » Wed Jul 30, 2014 6:07 am

I received the mechanical parts (fasteners, stand-offs, etc.) today and finished two more voice cards, bringing the total to five. One more to go.

They all boot up and make noise.

The display will arrive on Friday. If all goes well, I'll post demos this weekend.

justin3am's Mutable Instruments Ambika build now w/sound!