SA-432

The holy grail of mastering equalizers. A 1:1 replica of iconic Sontec MES-432.

The Sontec MES-432 was one of the first fully parametric stereo studio equalizers built in the mid 70’s. With fully stepped switches, surgical precision and extremely musical op-amps, this EQ made its way on to virtually every single successful record in the 80’s and 90’s and it’s still used till this day as the go to equalizer for mastering engineers around the world.

The Op-Amps

At the heart of every Sontec MES-432 you will find six HS2030 and six HS6000 discrete op-amps. No other op-amp sounds the same and no other op-amp should be used in this circuit. After 2 years of meticulous measurements, auditioning parts and listening tests we successfully reverse engineered these amplifiers which are fully compatible with the originals. The original DOA’s were famously known for being unreliable and unstable so we took this opportunity to improve the original design with better heat dissipation leaving them unpotted for more stability and longevity which was one of the main concerns with the original. Just like the original unit they run at +-28V for extended headroom and are fully discrete with 13 transistors in each op-amp. The SA-432 features a total of six reverse engineered HS2030 and six HS6000 per unit.

The Circuit

Utilizing the original DOA’s plus respecting the original schematic and circuit allowed us to bring this legendary unit back to life in a stable and faithful way. The Q has been respected and is 100% faithful to the original. Fully stepped switches with 1% tolerance resistors have been implemented for perfect and surgical stereo matching and easy recallability. With its 0.5 dB steps for the first 3 dBs, it is perfectly suited for mastering work. The three parametric bands offer wide, overlapping frequency ranges for musical tone shaping.

The filter design is a Bridged-T-filter in the feedback loop of an op-amp. If you enable the bypass only the filter section is bypassed. The amp section with its HS2030 opamps is still active, just like in the original. A switchable Mid-Side matrix added for mastering engineers is available as an optional upgrade (500 USD)

Superior Components

Each SA-432 comes with a UK made toroidal transformer with a high-grade core and state-of-the-art power supply to ensure complete silent operation with Panasonic capacitors. Each band uses 1% tolerance resistors and matched WIMA MPK and Polystyrene capacitors as well as Neutrik XLR connectors have been implemented with period-correct knobs.

100% satisfaction guarantee – if you don’t love your SA-432, we’ll refund you

If you’ve used an original Sontec 432C before, we’re extremely confident the Stam Audio SA-432 will put a big smile on your face every time you use it. However, if you’ve never touched the original before, as gear-lovers ourselves, we understand that the only way to really know if this compressor is for you, is to put it through its paces. That’s why the SA-432 comes with a 30 day money back guarantee. This allows you to get it into your rack and see how it impacts your recordings. If you love it (and we think you will!), great…keep the unit and create amazing music with it. If not, no problems. Just send it back to us and we’ll fully refund your purchase.