What is it?
The Ambika is a DIY hybrid 6-voice polysynth with a digital oscillator section and analog filter and amplifier (VCF and VCA). You can also choose from 3 different filter choices, which include: a Roland-like analog 4-pole LPF (SMR4); a second more edgy 4-pole LPF (4P); and a multi-mode 2-pole SVF filter. You can also combine different soudcards inside a single unit. The operational system is open source and can also be edited and hacked by the user.

I can't really tell you how difficult it was to build it because I didn't build it myself - living in Brazil, it wouldn't cost me any less than U$2000 to import all the materials and pay some heavy taxes, so I decided to buy it from an authorized builders list available at Mutable Instruments' forum.


Hardware
Considering that this is DIY thing, build quality is pretty much subjective, but I think that one can evaluate the overall feeling of the synth, and what I can say is that it is very good. A beautiful translucent/transparent case, correctly sized LCD, good interface with a button press - page change style.

Connection-wise, you get MIDI IN and OUT, one mono mixed output for a mix of all voices, a single mono output per voice individually. There's no headphone out or audio in, which is a shame. You can't run external audio thru the filter like you can with the Shruthi... this is probably due to the small footprint of each soundcard (there's no more space on the back of the unity too).

Power supply is provided externally by an AC 1A 9V with a 2,1 mm barrel connector, which wasn't hard to find, but it's large and adds some weight to the thing. It is good to notice that the unit doesn't get considerably hot by using this power supply, not even after hours of fun.


Interface and specs
As said before, the synth has a digital oscillator section that goes to a VCF and VCA. The interface used to control each section of the synth is pretty good. No, you don't get the control you would with something with lots and lots of knobs, but they've done a good job with restricting the size, making it affordable and very intuitive when tweaking.

The whole interface is based on a page system that is pretty intuitive. You press a button and gets the parameter of each section on the screen. The switch 1 gets you to the oscillator page 1, and a second press takes you to page 2. You can also navigate thru pages by using the encoder on the right side of the display, which can also be used to tweak the parameters in a more precise way. Every switch is coupled with its own led that shows where you are by changing its color (yellow, orange, green). Besides that, there's also a few shortcuts that make our lives easier.


Voice allocation
This is one of the best features found within this synth. The Ambika allows pretty much everything one would hope on a polyphonic synthesizer. You can use it as a 6-voice polyphonic synth, 6 monophonic synth and everything in between. You get a freely selectable voice allocation!

Not only it is able to provide you 6 different monophonic sounds, but that sounds carries everything you'd want, such as arpegiattor configuration, sequencer notes and modulation values. It's having 6 individual sounds completely, which may be accessible at different MIDI channels. This is the most powerful voice distribution system I've ever used on a polysynth.

Before you start wondering... yes, you can mix up voicecards with different filter flavours. You can use for example, the combination of a 4-voice polysynth SMR4 + bass monosynth 4P + highpassed mono lead SVF. As I've said before: freely assignable voices - the voicecards can act together but also independently.


Oscillator section
The most notorious part that makes the Ambika an hybrid is the oscillator section (although envelopes, LFOs and other modulation/arpeggio stuff are also digital). This is one sums up a lot of great wavetable oscillators, having some more traditional options as well.

Considering traditional waveforms, there's not much aliasing to high pitched notes, since they're band limited.this doesn't mean that you don't get some artifacts, which you do, but they're not gigantic. On the other wavetables, aliasing may be huge, and the synth acts better on the mid to lower-range sounds.

Since the most important feature of the oscillators is not using them raw, most of the available wavetables grants a very good start to making our own sounds, and they blend beautifully with the VCF, which removes a lot of the aliasing dirt, leaving only a "pleasant dirt" on the overall sound.

As for the wavetables, they include a few special waveforms, including Casio CZ-like, PPG inspired, metallic tones, EP and organ, filtered waveforms and more. It's an amazing choice of wavetables, richly described in the user manual.

The basic features of the wavetables include scanning the wavetable (parameter), tuning +/-24 semi-tones, detune of +/- half semi-tone. Other than that, you get oscillator modulation (with ring, sync, x-mod and fold), noise, sub-oscillator OR transient generator (which adds a fast and percussive attack sound), fuzz and bitcrush.

A special attention should be given to the amazing digital fuzz. This thing can act as a destructive effect, but also to give warmth to the digital oscillators, and it sounds GOOD. Small amounts can give rich and beautiful analog-like sounds.

Another important thing to remember is that you can modulate almost every parameter described here, as specified ahead when we talk about modulations.


Filter section
My Ambika is a 6xSMR4 filter, so this is the one I'm going to rate. Tone-wise, this filter is one of the most pleasant I've ever heard, and has a very Rolandish sound. It ranges from soft and creamy to almost aggressive, but never really reaches that screaming sound you get from a vintage Korg MS-20 or Polivoks. It is just beautiful, and marries perfectly with the oscillators.

It has some other interesting sonic capabilities, being able to sound close to the TB-303 sometimes (it's not something that I love and would really know how good it does a TB sound), but it sounds more close to a vintage Juno.

One thing that bothers me a bit, is that when fully open, the filter reveals a background noise on the oscillators (only when they're ON) that isn't really appealing. My filter wasn't perfectly calibrated either, so it's pretty much impossible to use it polyphonically as a sound source. Maybe I'll try fixing this to use it when needed...

Although it is able to do some percussive bass drums, one weird aspect of it is that is looses volume, and its quite hard to match a sound that uses the oscillators... it's simply low, and I don't know why that happens.

The available parameters for the filter are few: cutoff, resonance, envelope to filter and LFO to filter. You can rout other things to the filter via modulation matrix, but I think that having them on the filter page would be even nicer (and also make space for other modulation routings on the mod matrix). There's currently a few OS hacks that adds velocity to filter and keyboard tracking, directly at the filter's page.

There's one last thing I'd like to see implemented: audio-range modulation to the filter. I don't know if its possible, but it would be very nice to have oscillator 1 being used to modulate the filter cutoff. To me, this is an amazing feature and would expand the sonic possibilities.


Envelopes and LFOs section
This is an interesting part, although not the richest one. The interesting side of it, is how they've implemented an easy way to tweak the 3 available envelopes and LFOs on the fly. In a single page, you have the first knob to change between the 3 different sources and the rest of them are responsible for editing things... you can edit envelope 1 and LFO1 in the same page, and you don't need to click anything to navigate between different sets of envelopes and LFOs (1, 2 and 3). It's really easy to use...

The envelope speed is very good, and you can get some very fast percussive sounds with them. The overall range is pretty good too, which allows a great scale of sounds. Snappy drum sounds or long pads, you can have both.

LFOs aren't so fast as they should've. To me, being limited and not achieving audio-range frequencies is not a good thing and its one of the limitations that I don't enjoy. In the end, they're just as fast as the many other available VAs on the market - I'm just getting used to have this, since I'm spoiled by my Moog synthesizers. Although rate-limited, theres a very good selection of available LFO waveforms, which make the LFOs more impressive then they seem to be at first... some unconventional waveforms really add a lot of amazing possibilities to the synth. It's also important that the 3 aforementioned LFOs are all synced in all voicecards.

You have one free envelope/LFO (1), and the others (2 and 3), are hard wired to VCF and VCA, but can also be used to modulate other things via mod matrix. To me, not the strongest side of the Ambika, but its good enough to provide a wide range of sounds.

There's an additional LFO, named voice LFO, on the next page. This LFO is individual per voice and unsynced, which provides a moving sound for each individual voice. It's a good way to give the Ambika some analog mojo if you use it to discreetly affect the oscillators pitch. This LFO doesn't have all the rich waveforms available on the other 3, being limited to the more traditional triangle, square, saw and sample&hold.


Modulation Matrix
Mod matrix On the Ambika is pretty much simple to describe: there's 14 available slots and you can use pretty much anything you think (besides the oscillators itself) as sources and almost everything as destination (almost every available parameter).

Here is where you can really start playing to get some unconventional synth sounds, and really makes this little beast even more powerful. You can use envelopes and LFOs to control the wavetable scanning, sequences to modulate cutoff/resonance, velocity to control envelope to LFO amount, just to name a few... it's pretty much deep and the end results are endless.

The other interesting thing is the available 4 operators... these are math operations used to combine two modulation sources in some interesting ways (like the product of both) and use it as modulation source on the 14 available slots. Although hard to really describe it in all its complexity, using it may get it easier to understand. The user manual is pretty poor on describing how to use these operations, but with time, one can get to understand it all.


Arpeggiator and sequencer
Another nice addition to the Ambika... a very nice arpeggiator combined with a limited, but powerful sequencer. As said before, everything is individually configured in each part, and if you want, you can use 6 combined arpeggios/sequencer for each of the 6 parts, creating 1-finger instant music/jamming sounds.

The arpeggiator is a fully featured basic arpeggiator, with note division, selectable octave range and everything you'd hope for, but also has 22 different arpeggio variations which add an immense variety to it.

Sequencer-wise, you have a 16 steps note sequencer and a parameter sequencer that must be set to modulate parameters on the mod matrix. The note sequencer would be better if included 32 steps, but 16 is enough to allow some basic electronic music patterns than can be transposed while playing. The other sequencer is a combination of 2 16 step sequencers that may be combined to get the maximum of 32 different steps. The overall size is pretty much a mystery, and combining different sizes for sequencer A and B can give unrepeatable patterns for more than 20000 steps.

Since its not my objective, I'm not going to extend myself with this, trying to explain how to get these unrepeatable patterns. What is important is that you can do it!

One thing that one should notice... editing this sequences can be quite a pain in the ass, and as it is, there's no way to use an external controller to adjust the steps in the current OS.

With all this, you can combine different arpeggio/sequencer lines and create interesting beats using nothing more than the Ambika. TB-style patterns are also easy to acquire, since the note sequencer has control for velocity and linking notes.


Keyboard and polyphony handling
The voice allocation part of this review explains how voices are handled within the Ambika. Here, we'll talk more of how you can use it considering how you play the keyboard.

The available options are poly, mono and duo. The polyphonic uses the desired and selected voices polyphonically. The duo assignment makes use of two voicecards per voice, making a 6-voice polyphonic a 3-voice polysynth. The monophonic uses the selected voice for a single sound, providing both traditional mono sounds and unison sounds (with 2 to 6 voices). For both mono and duo, there's a parameter to control detune between the voices. You can also control if legato is on or off, and also glide amount, which can be used with polyphonic sounds too.


Library
This is where the Ambika allows the user to save a few different kind of data. There’s program, patch and multi. For this review we will only look to program and multi. A program is a single sound, saved with it’s own synthesis parameters. A multi is the combination of a program and all other configurations, such as sequencer, but also saving the voice allocation configuration (which part is what).

Using multi is a nice way to keep complete combinations of sounds. It’s interesting to notice that you can use your saved programs to be a part of a multi. You can save a program and use it several times in a combination of sounds… imagine that favorite lead or bass sound - you can use it several times without having to save it once again.

The amount of data that the Ambika can handle is pretty huge. You have A-Z soundbanks with 128 sounds in each one. This A-Z thing isn’t limited only to programs. There are dedicated banks for programs, patches and multis. This gives the user a lot of blank banks to fill with sounds.

Presets… the included factory ones are GREAT. The programs (there’s pretty much nothing in the multi department) explore deep sonic possibilities with the Ambika, and most of the available demonstrations for the Ambika are using them. You get almost 250 sounds with a great quality, ready to be used, easy to tweak to get new results. One of the Ambika’s highlights.


Performance page
Another great addiction to be used when performing live or even tweaking things. The performance page gives the opportunity to save eight parameters from all the possible ones, to be tweaked in the same page, even for different parts. You can set up this page to control the filter cutoff for two different sounds within the same page. It’s a really a good idea.

Although you have this, there’s no dedicated performance mode or something that stores sounds in a correct order to be used live. Recalling sounds also require pressing the library switch and turning the encoder. It’s not really practical in a live ambient, but similar to other high-end gears such as Dave Smith Instruments’ ones.


Sound-wise, is it good?
Good? It’s amazing. Even with all the aforementioned “flaws and missed things”, one thing is certain: the Ambika is a titan sound-wise.

There’s a large selection of possible sounds and they all sound amazing. This thing isn’t a Moog bass-wise, but sounds better than the Prophet '08 for example. I didn’t expect it to be so good at the bass frequencies, but it is. The available wavetables combined with all other features are also able to give some interesting metallic tones and great drone sounds.

In the end, the digital oscillators gives the Ambika a wide range of sounds, that combined with the marvelous filter design, provides a sound that is not only beautiful but also powerful. I’m totally in love with it, and I think that it is already one of my favorite synths.


Final considerations
Considering that this is a DIY synthesizer, I think that Olivier, responsible for Mutable Instruments, did an amazing job by providing us this. It is so amazing that it is not only a toy, but a serious instrument that can hold its own against several pro-hardware such as Moog or DSI synths. It’s certainly incredible in all levels.

When you take a good look, it provides something that for the asked price (~U$600 to do it yourself to U$1250 to get it done for you), is uncomparable. Having a powerful instrument in such a small footprint is also impressive.

A fully-featured synthesizer, with a strong and characterful sound, that provides the musician ways to be creative and explore several synthesis approaches - this is the Ambika.