Sound Semiconductor Intros Updated Version Of Classic SSM2040 Analog Filter Chip

Sound Semiconductor has announced a major addition to its product family with the SSI2140, an improved version of the classic SSM2040 chip design, by original designer Dave Rossum.

The SSM2040 Voltage Controlled Filter is considered by many to be one of the best-sounding synthesizer filter ICs ever produced. It was notably used in the Sequential Circuit Prophet 5 Rev. 1 and 2.

“When we started this enterprise, a SSM2040 update was on our short list,” stated Dan Parks, President of Sound Semiconductor. “Dave Rossum was anxious to take this on, and as the project progressed he devised new ways to improve functionality. Early users have attested to preservation of SSM2040 sound, and some claim that Q Compensation ‘sounds huge’.”

Here’s what Sound Semiconductor has to say about it:

“Following completion of the SSI2144, which is an update to SSM’s other famous filter, Sound Semiconductor turned its attention to the SSM2040. First and foremost, the basic transconductance core was left unchanged to retain its sound characteristics. However, process technology and design know-how advances permitted the addition of new features.

Like the SSM2040, the SSI2140 contains four independent transconductance cells that can be connected for a wide variety of filter pole and mode configurations such as low-pass, high-pass, all-pass, band-pass, Sallen & Key, State Variable, Cauer, and many others. To improve temperature sensitivity, gain core cells are temperature-compensated.

Similarly, optional temperature compensation is available for the exponential port that provides a wide range of control using the SSM2040’s same constant of -18mV/OCT.

A major addition is an on-chip “Q-VCA”, also temperature compensated, that allows easy control of resonance (“Q”) and supports numerous optional Q compensation schemes to overcome attenuation of passband frequencies as resonance increases. Should the Q-VCA not be needed for resonance or compensation, it can be put to work for traditional VCA or VCF applications such as, for example, a single-pole high-pass filter.

Finally, like the SSM2040, the SSI2140 has an input overdrive characteristic that many believe contributes to the filter’s coveted sound.

Due to a different package type and pin connections, the SSI2140 won’t directly retrofit SSM2040 PCB positions, but third parties are already developing adapter boards. One outfit has even developed a single board to adapt the SSI2140 to Rev. 3 Prophet 5’s.”

Pricing and Availability

The SSI2140 is offered in a 20-lead Shrink Small Outline Package (SSOP). Priced at $1.18 for 1000 pieces, the SSI2140 is in stock for immediate shipment. Samples are available to qualified OEMs; hobby and DIY enthusiasts are served through Sound Semiconductor’s authorized resellers.

21 thoughts on “Sound Semiconductor Intros Updated Version Of Classic SSM2040 Analog Filter Chip

  1. “Like the SSM2040, the SSI2140 contains four independent transconductance cells that can be connected for a wide variety of filter pole and mode configurations such as low-pass, high-pass, all-pass, band-pass, Sallen & Key, State Variable, Cauer, and many others.”

    So when are we going to get synthesizers with switches and dials that allow us to choose between all of these filter configurations on one machine? It’s about time there was a successor to the Matrix 12 / Xpander in terms of functionality, and now that there are so many different oscillator technologies (both digital and analogue) it seems as though several different manufacturers could implement this kind of versatile filter while still offering their own unique take on the oscillators.

    1. When the average synth buyer are willing to pay for R&D rather than a race to the bottom like some companies I won’t name.

        1. Bill

          As noted in the article, the updated chip was designed by the original designer, synth guru Dave Rossum. The company is run by Dan Parks, who is the the same guy that ran SSM.

        2. Bill, are you really accusing Dave Rossum of ripping off his own work? Unlike the people at The Companies We Won’t Name, he actually understands his designs.

      1. Agree with this. RTTB in high volume not only impacts big brands but it takes away customers from small companies which could to bring products to the market using off the shelf parts at comparable prices. Companies who have the capability to make custom, proprietary hardware have a big advantage. Unfortunately this also stiffles creativity and innovation by not making those available to 3rd parties.The larger music industry technological companies should support artistic creations by sharing technology but unfortunately most of them are hugely self centered.

      1. The application notes for the SSI2164 are amazing, thanks for posting them! I can only assume the application notes for the SSI2140 are similar.

        I’d love to see a synth where each voice has both an SSI2164, with switches for all possible filter implementations, and an SSI2140, with switches for all possible filter implementations, and the ability to route oscillators to the filters in series or in parallel. *Now* I might be getting carried-away, but that would make for an absolutely awesome filter section… and there would still be so much that could be done with the oscillator section (analogue, wavetable, FM, wavefolders, rompler, sampler… the list goes on).

    2. The reason for using a single chip is mainly cost. So if your adding a lot of peripheral components such as relays, transistors and control logic to switch between states that defeats the purpose of having it all in one cheap chip.
      But there are synths like the MFB Dominion 1 for example that offer more than 15 filter types.
      My bet is that the majority of users still put it in low-pass mode and are done with it, so in a lot of products the cost and R&D is not motivated.

  2. SSI is a solid company. They make improvements to the old parts such as negative rail protection for the 2164 (powerup) and better temperature compensation in 2144 and 2140. For a good while they were simply too expensive to compete with Coolaudio and BOM costs would skyrocket when trying to use SSI. At some point the prices dropped significantly and they are now competitive with coolaudio. Been using the 2144 with no problems and looking to switch over to their 2164’s.
    Some of the parts are SSOP vs SOIC so have to pick SSI, Coolaudio or other during design phase.
    I hope they continue to do well and release more stuff. Helps when you have DSI/Sequential to order 100k pcs to kick off production!

  3. The application notes for the SSI2164 are amazing, thanks for posting them! I can only assume the application notes for the SSI2140 are similar.

    I’d love to see a synth where each voice has both an SSI2164, with switches for all possible filter implementations, and an SSI2140, with switches for all possible filter implementations, and the ability to route oscillators to the filters in series or in parallel. *Now* I might be getting carried-away, but that would make for an absolutely awesome filter section… and there would still be so much that could be done with the oscillator section (analogue, wavetable, FM, wavefolders, rompler, sampler… the list goes on).

    1. exactly, the next Sequential will be another prophet w/ the 2130 VCO & 2140 VCF… sort of a Prophet 5 rev1/2. There is really no debate about it, I’m 100% certain. They already have the platform w/ the P6 and OB-6 and only need to change the voice cards. I think Sequential is a huge factor in SSI making these parts. They are local in the San Francisco area and they’re all old friends… I think Sequential helps fund the manufacturing of these chip by placing very large initial orders.

      1. not sure about that. Dave has already do the Prophet 6. He won’t revisit it again I think… If he would that would be a kick in the teeth of the Prophet 6 users. Let’s hope he”ll try something new. He said during an ITW that his next instrument will be for another type of musician (in comparison to the Pro3).

        1. Don’t know about the REV2, but it could be hardware architecture (excluding the voice) behind it might be very similar to the OB6/P6 as REV2 , as it has integrated chips that save space to cramp those 16 voices in a small box. The problem might be more a marketing thing how to name this thing, Prophet 10X ?

    1. modular grid (i think? or someone else) make a through hole attachment for the SSI2144 I am sure a similar thing is coming here.

  4. I have a complicated relationship with SSM synths. I(‘ve) own(ed) a Siel Opera, Siel DK80, Korg Mono/Poly, Crumar Bit One and Kawai K3 with SSM IC’s. The filter always sounds really wet and juicy, but at a certain cutoff/resonance ratio the amplitude suddenly drops. I hope this is what the “Q-VCA” feature is adressing.

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