LushOne Base – High pass filter mod

Changes to convert the LushOne Base filter from low-pass to high-pass

Once the LushOne had a fairly complete set of basic synthesizer functions available I always intended to built a powerful multi-oscillator and multi-filter system. You may laugh, but in the back of my mind I had the brief-case sized systems built on the boutique Mattson Mini Modular components.

Once you start thinking about building a full system then you are going to want a high pass filter option to complement the low pass filter in the LushOne Base. Fortunately it is easy to modify the LushOne Base filter to be high pass instead of low pass. Here are the changes:

• Omit R218 and C210 and instead link the two footprints with a wire as shown on the left.
• Change the value of C208 to 2.2nF. This is the same value as C210 so you can do a substitution there. Obviously this capacitor is now non-polar so ignore the polarity markings on the PCB.
• Change R221 to 4.7k
• Change R220 to 47k

That’s all there is to it! Sit back and enjoy some new sounds.

Generally the low pass filter is more useful so if you only have one LushOne Base then I wouldn’t make this a permanent change. However if you want to build a system with more than one LushOne base, or if you want to take the LushOne Base schematic and build your own filter on vero-board then it’s well worth having a high pass option.

If you are using both the filters I recommend putting the high pass first in the signal path and then the low pass. This will reduce the risk of any high-frequency noise getting though in to the output. This arrangement can produce quite natural sounding instruments from the LushOne oscillators.

Remember that with both a high pass and a low pass filter it is rather easy to cut the signal off all together by having non-overlapping filter bands!

Here’s a little multi-tracked sample from a dual-filter LushOne: