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REVIEW: Dave Smith Instruments OB-6

A modern classic with a toe in the past

2021 Sep 29     
2 Bit Thugs

When two of the world's top synth designers team up, the results have got to be worth investigating…

The OB-6 is the brainchild of two of the most respected synth designers in the game, Sequential’s Dave Smith and Tom Oberheim. For those that know, there is no need to stress the importance of these two figures; for those who don't, just be aware that between them they've been responsible for designing some of the finest electronic instruments ever made. 

The keener-eyed among you may have noted that the OB-6 looks very similar to the Dave Smith Prophet-6: well, that's not an accident. Seeing no need to reinvent the wheel, Dave and Tom have taken the very robust chassis of the Prophet-6 and popped in an SEM-driven Oberheim synth engine. 

I first discovered Oberheim because I'm a huge Prince fan: many of his trademark sounds came from a variety of Oberheims, often the Four Voice and the OB series. But with there being very few old Oberheims on the secondhand market, your chances of getting your hands on one are slim – and it'll be expensive if you do. So will this collaboration finally fill the dream analogue polysynth void?

Let's see…

Synth engine
One of the many factors that inspires such devotion to analogue synths is the tactile, intuitive layout. Everything that you need to play and perform is right there on the front panel. There are no hidden functions, everything has its own dedicated knob, and such is very much the case with the OB-6. This makes the process of crafting your own sounds an easy and immersive one. 

On a performance level, the knobs are calibrated to perfection, and the filters are a joy to modulate: just set the arpeggiator running and you may find that you have lost a good chunk of time down the filterscape rabbit hole! 

The immediacy and responsiveness of having everything laid-out like this cannot be overstated: anyone who's ever scrolled through menus on a digital synth or edited a VST with a mouse will attest to the fact that it can be a daunting, laborious experience. There’s none of that here: the OB-6's quick, inspiring functionality will keep you coming back to it time after time. 

The science bit
The OB-6's synth engine is inspired by Tom Oberheim’s SEM module, which was originally designed to compliment other synthesizers, but later came into its own as a great- sounding synth in its own right, as on the Oberheim Four Voice. Its unique filter has become something of a unicorn in the analogue synth world as it allowed you to sweep from low-pass to high-pass, giving it a sound that no other had.

The OB-6 features two discrete voltage-controlled oscillators (plus sub-oscillator) per voice, with continuously variable wave shapes: sawtooth and variable-width pulse, plus a triangle wave on oscillator two. The classic Oberheim-inspired two-pole, state-variable resonant filter provides low-pass, high-pass, band-pass and notch functionality. Voltage controlled amplifiers complete the all-analogue signal path.

In use
The sonic character of a synth matters a whole lot, and due to the SEM cards the OB-6 has a particularly unique one. 

The raw tone of the oscillators somehow manages to be simultaneously warm, bright and biting, and they sound massive! This allows them to cut through the mix and stay big and present in a way I've rarely encountered. Many synths find it difficult to poke through a dense mix and tend to get lost without a liberal helping of EQ, but the OB-6 slices through like a lightsaber when required. The drifting instability of the VCO is gorgeous and is a reminder of how hard software developers work to try to emulate this analogue behaviour.

I've mentioned how raw and cutting the sound of the OB-6 can be, but don't get the impression that it sounds harsh. It certainly can do, if such is your intention, but this is such an expressive instrument that it can turn its hand to anything. To my ears it's pure 1979 analogue: thick, creamy and rich, just like your Nan’s custard. 

The pads that can be conjured are pure bliss: warm, fat and detailed with massive width and presence. Put on a pair of cans, hold a chord and turn up the pan spread knob for the ultimate in widescreen sound design. For bass as well it's perfect, and anyone who has a penchant for Italo-disco will be smitten with the lush grit it spits out at you. 

The sonic depth of the OB-6 is incredible: it's every bit as likely to be used for film scores as it is for techno, and it's as happy in the world of experimental atonal composition as it is serving up Prince-like brass hits.

While we're not talking about reverbs in the same league as dedicated units like Lexicon or Eventide, the ones onboard here are of very good quality and are perfect for adding a little more depth and space when required, The distortion is great for adding more bite and warmth, and works well on bass and percussion. 

The delays predictably are also on point and will have your sounds splintering and shattering into controlled chaos without too much sweat on your behalf. The ring modulator in particular is amazing for pushing the sound design envelope into the realms of brutal techno filth!

Performance functions
The arpeggiator section is fairly comprehensive, giving you selectable note values of 16th note, 8th note triplet, 8th note, dotted 8th note and quarter note. You can also span one-, two- or three-octave ranges, and try different note order combos with up, down, up/down, random and assign modes. 

If you want to hold a chord or arpeggiation, just hit the Hold button to free up both hands for tweaking, while if you're looking to lay out something a little more structured then the polyphonic step sequencer will come in very handy, giving you up to 64 steps and rests. 

The chord memory function is a joy to use as well, and is great for generating pads and stabs.

With a pretty hefty asking price of around £2,000 for the desktop model we reviewed or £2,500-ish for its keyboard-toting sibling, it would be a dereliction of duty on our part not to point out the OB-6's weaknesses – though there are honestly very few. 

It would be nice to have a full LCD screen to give your patches names and to help facilitate some of the under-the-hood features such as alternative tunings, but here we are limited to a three-digit numerical system – so either a good memory or pen and paper will be required for keeping a record of your favourite patches. 

Also, the Blade Runner-style blue-on-black colour scheme may not be ideal if you are performing in a dark environment: the letters don't exactly jump out at you Whether or not this particular design is the most practical will greatly depend on how you wish to use it, but if you are playing live, be aware you may need a torch…

In conclusion
Put aside any prejudices you may have about modern synths not being as good as vintage ones. The OB-6 is more stable, cost-effective and flexible than any other synth in its class: many modern analogues sound great, to be fair, but this one sounds spectacular!

Conjuring those much-loved Oberheim sounds from the vintage era, the OB-6 is a modern classic with a toe in the past.

Words: Chris Lyth





Tags: Dave Smith Instruments, Tom Oberheim, OB-6, Prophet-6, synthesizer, analogue synth, review