It already has been a few years since old hack Dave Smith started putting out new analog synthesizers on the market. This renaissance of analog synths means having more instruments to pick from for us musicians. Funny enough it just was short after the FM synthesizer patents of Yamaha ended which were responsible for the major part of the decline of the analog synthesizer market during that time.
Evolvers where the first relatively simple models which were picked up by the users fast. After that they started to design more models with keys and polyphonic versions which were also a success. After that he decided to release the current flagship synthesizer the Prophet 08. A common day version of the legendary Prophet synths from the 80ies. The call for smaller cheaper units resulted into the Mopho and the Tetr4. The Tetr4 in fact is 4 times a Mopho put together in one case without the analog filter input.
The Tetr4 is a 4 voice digital controlled 2 oscillator synths with analog signal path including 2-pole or 4-pole analog filters. Also included are 4 LFO, 4 sequencers, modulation matrix, midi, USB, 4 assignable controllers and an option to chain them with other DSI synths. Extra’s are that both oscillators have a sub (square waveform) oscillator and that it can be use as a multi-timbral synth as well with every voice having it own output (4 in total).
I started checking out the presets to get an impression of the sounds this small box could make. Plenty of bas, leads and FX sounds. The basses have lot of firm low end. Leads tend to scream a bit. There are also quite a few of brass type of sounds.
While checking out sounds you tend to edit the sounds a bit. The editing itself is inspired by the 90ies a bit but way more practical. There are 4 assignable knobs which can be used to assign parameters to at assign mode. In normal mode you can change the values of these knobs and the 4 fixed controller knobs for cutoff, resonance, attack and decay as well. The extra pitch controller knob doesn’t make sense to me because I would use it that often.
The editing is quite extensive because of the many parameters you can adjust including the 4 sequencers. Starting to use the editor you can download to do this will make a lot easier. This editor is made by a 3rd party company called Soundtower and you can use the USB or Midi to communicate with the Tetr4. The ‘light’ editor you can download for free for PC (XP/Vista) and Mac(OSX). With this you can edit all parameters of this synth. The pro-version has more options for patch management.
You also can use the 4 voice in combinations. As unison patch or as layered/split A/B duo phonic patch. Or combining separate patches as a multi-timbral combo. This last combo mode eats up those 4 voices very fast.
After trying the 4×128 presets I started to dig deeper into the bowels of this synthesizer. I notice that the oscillators only have a saw,tri and puls waveforms (99 variations). I’m missing the sinus and square. 50% pulse doesn’t sound like a square that I’m used from your typical analog synth. You can use the square waveform from the sub oscillator though. You can create a sinus by filtering a triangle or using the self osciallation of the filters. The filters really sound analog and start to self oscillate at high resonance values. The cutoff frequencies has values 0 to 164 so it will require NRPN midi message to control since normal midi controls can go from 0 to 127. You don’t hear any stepping during turning the cuttoff knob btw.
The presets themselves only give away a small amount of sounds this synth can produce. You can get way more out of it when you invest some time into it. Especially when you use the editor to keep an overview.
In a test I tried to layer the Tetr4 with an Alesis Andromeda A6. Also a contempory analog synth. But trying to fit these sounds together was extremely difficult. The sonic character of both synths differ way to much for that.
Personally I think that every polyphonic analog synth should be able to produce decent analog string sounds which the Tetr4 only can do to some extend. The sound that comes closest to that are brassy type of strings.
To my surprise the Tetr4 can be use as a replacement version of a SID chip. This is also a digital controlled analog synthesizer on a chip. With some creativity and smart programming you can get far. Using the editor to edit the internal sequencers gives it an extra dimension. It took me a tip from DSI that the number of sequencer steps can be changed by using the reset function for each step. Might be interesting to add the return function so you could have ping/pong like sequencing. The fact that you can route sequencer parameters to values gives the synth engine an extra dimension.
Also not so common for a common day synth is the lack of internal effects. If you use other effects it works fine. But for the people with a limited budget it will mean having to invest into extra effect unit(s) or extra IO’s on the computer. The Tetr4 sounds raw so not all effect units are suitable for this synth.
The Tetr4 is a very useable synth with limitations. It excels in bases, leads and FX type of sounds. In terms of styles you can think of Electro pop or dance types where deep/subtle base sounds are usefull. They are way better than your typical software synth type of base sounds. The way you have to handle the waveforms differs a bit what you should expect from a typical analog synth.
The dimension of the synth and the ease of use make it suited for live gigs. But then you probably would have like an analog filter input as well which the Mopho has.
People willing to spend time digging deep into this synth and like turning knobs will enjoy this small relatively cheap synth with an authentic analog sound.
We would like to thank Dave Smith for the review unit. More info about Dave Smith’s gear at www.davesmithinstruments.com