Bubblesound LP40 & HP40, new filter modules based on the SSI2140 chip

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Bubblesound LP40 & HP40 are two new slim format filter modules for Eurorack powered by Dave Rossum’s updated SSI2140 chip.

Filters come in many different designs. With more or less features or other chips. One of the well-known is the SSM2040 chip from that is installed in the iconic Sequential Prophet 5. In 2020, Sound Semiconductor updated Dave Rossum’s chip and released the SSI2140, which is also built into the new Prophet-5.

Bubblesound has now also built these new chips into new slim analog Eurorack filter modules.

Bubblesound Instruments LP40 HP40

Bubblesound LP40 & HP40

LP40 & HP40 are new compact 4HP lowpass and high pass filters based around the new SSI2140 filters, the successors to the legendary SSM2040. This chip can be found, for example, in the vintage Sequential Circuit Prophet 5. Its beloved by many because of its unique behaviour.

The feature set is very similar in both modules. You get cutoff and resonance controls. The cutoff is CV-controllable with both positive and negative voltages while the resonance offers CV control with 0-10V. The developer says the input is set up like on the Dual SeM20 module: “when the indicator line is straight up the input is at full, anything past that will over drive the input”.  Both filters also track 1V/Oct with internal temperature compensation.

Then, you get three different output types and 4 outputs: 12 and 18dB have one output each and there are 2 24bB outputs. Clever, if you are using a single 24dB output, you can take the second and create a variable band width band pass type by sending it to the HP40 module.

Further, the LP40 has a bass compensation feature that keeps the resonance and signal level balanced all the way down. These filters are pretty unique. The LP40 is capable to create smooth and creamy filtering sounds but also dripping acid timbres with a simple turn of the resonance pot.

On the other side, the HP40 is unique filters that makes Roland-style HP timbres possible. And not forget, it can resonate and thus create unique, magical timbres. From fragile, and band brittle leads that vanish into the air to sweeps and hollow thumping kick drums .


There are currently no sound demos, a pity, but two interesting compact filters powered by a legendary chip.

The Bubblesound LP40 and HP40 will be available soon and will cost $169 USD each.

More information here: Bubblesound Instruments

BS Instruments are available at our partner

Perfect Circuit

Eurorack News

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