The Stam Audio SA-3A+ is a dual-channel optical compressor that combines two of the most celebrated solid-state opto designs in recording history—the aggressive mid-range punch of the UREI LA-3A and the ultra-transparent levelling of the UREI LA-4—into a single 2U rackmount unit. Handcrafted in Chile using period-correct componentry, the SA-3A+ addresses the original hardware’s noise-floor limitations while expanding its operational range for modern hybrid tracking and mixing rigs.

What elevates the SA-3A+ above typical vintage clones is Stam Audio’s component selection and hybrid circuit design. At its core, the unit utilizes super-stereo matched Kenetek T4B optical cells alongside custom US-made autoformers, custom input transformers, and UK-made Carnhill output transformers. By providing discrete switching between the classic T4B opto circuit (LA-3A mode) and an integrated Vactrol circuit (LA-4 mode)—complete with selectable ratio switching ($4:1$ and $8:1$), high/low gain modes, high-frequency compression contouring, and front-panel stereo linking—the SA-3A+ acts as a complete solid-state opto workstation.

The Stam Audio SA-3A+ is an outstanding dual-channel dynamics processor for engineers seeking true vintage solid-state opto performance without paying astronomical prices for original UREI units. Whether slamming electric guitars for mid-range bite in LA-3A mode, smoothing out delicate acoustic instruments in LA-4 mode, or running full stereo buses through Carnhill output iron, the SA-3A+ delivers reference-grade analog authority and unmatched versatility.

Solid State Opto Compressor

Unlike any other LA-3A replica in the market, the SA-3A+ actually replicates the low-end and time constants with maximum precision thanks to its larger transformers and the best T4B’s in the market: Kennetek Pro Audio.

The Stam Audio SA-3A+ is also the only 1:1 sounding replica in the world of the beloved UREI LA-3A and UREI LA-4. Being the LA-3A the all time favorito electric guitar compressor and the LA-4 one of the greatest acoustic guitar comps in the planet it made sense to build both of them into a single unit.

Using custom wound US-made transformers, the absolute best T4B in the market made by Kenetek Pro Audio in Kentucky and a UK made Carnhill output transformer we can confidently say this is not only the most accurate sounding vintage LA-3A and LA-4 replica in the market but also the most versatile at any price point you will ever find.

Kennetek’s Super Stereo Matched T4B

Being the single most important part on a LA-2A and LA-3A and having tested every single T4B under the sun (including our own!!) we always come back to Bill Jones’s US hand-made T4B’s. It is simply identical to an original T4B from the 70’s and every SA-3A+ comes with a matched pair of them that exceed any matching out there. They are so meticously matched that you could even mix a stereo track though them. Without this component there is no accurate LA-3A replica. The SA-3A Plus also includes a Opto element found in the LA-4 which produces a more transparent compression.

The Iron

Since both circuits shared the same transformers, it was a no brainer to go the extra mile and give you two iconic compressors for the price of one by including the revered LA-4 compressor into the same unit. The LA-4 is famously known for its cleaner sound and all-time favorite acoustic guitar compressor. Each unit comes with a precise US-made input transformer and auto former replicas and a large Carnhill VTB11148 output transformers giving you the exact same character and frequency response as an old LA-3A.

Hand made with added features

Each SA-3A+ is hand built at our lab in Chile one by one with the highest quality components available. No shortcuts have been taken to ensure you can use them interchangeably with an old LA-3A or LA-4. The SA-3A+ now comes with a stereo link switch that allows you to use two of them in stereo, a high and low gain setting, a flat and high frequency compression selector, a bypass switch and a limit/comp selector which also acts as a ratio switch on the LA-4 circuit changing the ratio from 4:1 (comp) to 8:1 (limit).

The ultimate cure for “digititis”

While plugins have come a long way and are incredibly useful, there’s a reason the top engineers still have analog gear in their racks. And some of the biggest gains to be made if you’re mixing “in the box” is to use quality hardware on your tracks.

Legendary on vocals, magic on bass and a must have for electric and acoustic guitars the LA-3A and LA-4 are one of those rare pieces that just make things sound better.

• LA-3A and LA-4 in one unit (original schematic)
• Kenetek US made T4B optical cell
• Custom US made input transformer
• Custom US made autoformer
• Carnhill UK made output transformer
• LA-4 Vactrol Compressor
• High and Low gain
• Stereo Link for both compressors
• Limit and Comp switch (switches ratio 4:1 to 8:1 on LA-4)
• HF and Flat switch for both compressors
• Period correct knobs
• Bypass switch
• Vishay capacitors
• Hand made in Chile