Review: Brainworx bx_oberhausen

Brainworx bx_oberhausen Msrp $249 (introductory offer $179)

Best SEM emulation out there but also most pricey one to both your wallet as your CPU. This is an emulation of hardware with some valuable additions and not your run of the mill plugin instrument.

Afters years of implementing the most wonderful sounding emulations of world-famous analogue effects units Brainworx releases their first emulation of another analogue legend called the Oberheim SEM.

Since I’ve owned a SEM pro for several years now, I’ll be doing a comparison between the hardware the bx_oberhausen and the SEM2 from Arturia. The thing is that the SEM is an odd little box that unlike many of its contemporaries is not a one trick pony. Probably the main reason why this model has that many hardware reproductions or copies of the filters and oscillators. To reproduce this unique sound is quite the challenge in the digital realm and Brainworx put their teeth in that.
The instrument itself is pretty straightforward and by looking at the various parts of this instrument we can see what it’s made off. But in this case, there is more under the hood.

Two saw, pulse oscillators with pulse width modulation (PWM) on the pulse. A hard sync between the two oscillators used in combination with a pitched envelope on VCO2 can give you the typical hard sync sound the SEM is famous for. Additional are a FM mode and stereo spread modes (not on the hardware) which is very useful in unison mode. PWM linked to and LFO also delivers a sonic bliss that the SEM is know for. The FM mode tends to be more for sound design purposes IMHO.

One 12dB filter (VCF) with the modes low pass, band pass and high pass. The resonance goes well into self oscillation and sounds very convincing compare to the original hardware. It even matches this sharpish sounds that you can get when you use the filter for more extreme sounds. If you don’t like that sound too much and are looking more for a vintage sound you can add a 24dB low pass filter at 12kHz to take out the high nastiness. The filter also has a Mid Side option that seems to be more tailored for sound design purposes. Especially for polyphonic purposes a 24dB filter option might be interesting.

Two (ADS) envelopes and two low frequency oscillators (LFO) (the hardware only has one). LFO1 has a variable rate and is a saw just like the hardware. LFO2 can be synced to the host tempo, retrigger on note mode and has sine, square and saw shapes. LFO2 typically can be used in the mod matrix to give the sound a different spin. With the SEM pro you can do something similar if you have additional modular gear you can patch. To that extend sample and hold, saw up/down variants for LFO2 also could be interesting.

Next to the portamento mode you also can adjust the transpose and number of voices. From 2 voice to 32 voice unison is possible. You really unleash the beast when you use the unison mode with 4 or 8 voices. To that regard is a bit shame you cannot use polyphony and unison at the same time since any unison above 8 voices is hardly useful. When I tried a 32-voice unison voice my I9 (14-core) CPU was almost maxed out. So, this plugin tends to be a bit CPU hungry.

Brainworx added the Tolerance Modelling Technology (TMT) to reproduce that analogue imperfection and to me its the switch that makes this thing sound analogue organic or very plain. You’d never want to turn this off IMHO. If there is any resemblance to Yamaha’s virtual component modelling (VCM) is not clear to me but the idea is pretty much the same. The difference to CPU usages on or off is hardly noticeable so to that extend that should not be a reason to turn it off.

Mod matrix
Similar to the SEM pro here you also have a 9-point mod matrix to route the separate sources to other destinations and bypass the default routings. To that extend you’d really like to use this plugin in a virtual modular setup like Softube modular or VCV because SEM work so well in modular environments. The bx_oberhausen mod matrix also allows for different scaling options than linear for routings as well. Could be interesting to have both bipolar as unipolar variants for them.

The arpeggiator is pretty much straight forward and very useful. One thing about the time division is that the ordering of the time divisions is grouped in common, triplet and dotted. That doesn’t seem to be useful in a live environment where you want to play with the arpeggiator and time division values linked to a midi controller. Another thing I would like to see added would be a sequencer mode or phrase mode where you can play/edit sequences or phrases. That should work very well for ominous bass lines.

Unlike the hardware the bx_oberhausen also has a few effects built in to colour the sound. Overdrive, digital delay, EQ, flanger, chorus and reverb are presented like little stomp boxes and can be arranged in any order. Very straightforward and easy to use. The sound is what you would expect from Brainworx.

Midi learn
If you click the midi learn option right above you can link all coloured controls to any midi controller. You even can save the settings and attach them to other patches. Downside is that you have to do that for all separate patches. If you could make a midi setting globally might be helpful. Next to it is the global tuning option I’d wish all synths have.

The presets
The browser sections allow you to categorize and search for certain types of sounds
The bx_oberhausen has this unique feature to skip presets every 1-8 bars. Ideal when looking for a sound to match a midi track.

While playing with the bx_oberhausen I also loaded up an instance of Arturia SEM2 and added my SEM pro. One thing I noticed immediately that all did react differently to the same settings. So, if you want to make a comparison you need to tweak every unit to its unique settings and go from there. As far as the filter goes, they all sound very close. The differences are more about the different overtones the self oscillating filter makes. Obviously, the SEM pro sounds the most natural one with that. Then the bx_oberhausen came most close to that. But if you would put all in a mix you most likely will lose all sense of detail for both the SEM pro and bx_oberhausen.
Another patch I made for all units was a typical hard synced sound and they all sounded very close as well. Order of personal preferences didn’t change here as well. You start to spot the difference between the Arturia and Brainworx when you turn into polyphonic mode. The SEM2 sounds pretty balanced but the bx_oberhausen sounds much warmer. The difference in CPU usage is very significant though.


  • Warm sound
  • Added options


  • CPU usage
  • Price

The bx_oberhausen is the closest emulation of a SEM I came across. The TMT technology really gives it character that so may plugin instruments miss. The additions Brainworx made are very useful. Hopefully my suggestions also will be added in future updates together for more optimizations for CPU usage. Price wise the SEM2 is the cheapest and difference in price compared to the bx_oberhausen. The introductory offer of $179 is nice but $249 seems to be too high and $199 seems fair to me. It boils down to your personal preference which version you want to use in your projects. Myself I absolutely adore the SEM pro and for polyphonic duties have the OB-6 as well. Both plugins are very useful to anyone who likes to add the typical SEM sound. The bx_oberhausen just sounds better.

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