The Urei LA-4 has always been the quiet sibling of the LA-2A and LA-3A. Same optical lineage, same smooth levelling behavior, but held back by the realities of 1970s integrated circuit design. Stock units can sound a little dark, a little veiled, and a little noisy when pushed.

The Siret Mod is what happens when you take that classic opto heart and give it some fresh air.

Inside, the original RC4136 quad op-amp is replaced with modern high-slew, low-noise circuitry that finally lets the optical cell breathe. Power supply rails are rebuilt, the entire audio path is re-capped, and the unit is recalibrated from the ground up. What you get is not a different compressor, you get the LA-4 that modern productions cal for.

The difference is immediate:

- the top end opens up.
- the midrange steps forward.
- the low end tightens.
- the noise floor drops by a shocking margin.

Instead of haze on vocals or bass, the modded unit delivers a warm, clear and beautifully transparent tone with the same unmistakable LA-series levelling action. Transients are faster, the stereo image snaps into focus, and the unit handles hotter material without folding in the highs.

Engineers who rarely touched their stock LA-4s often describe the modded version as a “secret weapon” opto. Smooth on vocals, authoritative on bass, gentle on guitars, and clean enough for mix-bus glue. It’s still an LA-4, but finally operating at full bandwidth and full musicality.

Serial No: #3592A & #4654A

PSU is switchable between 100V and 240V, currently set to work on 240V. Fuse has to be changed for 100V operation. EU power cord included.

We ship worldwide, feel free to ask for a precise shipping quote.

The listed ex VAT / VAT0% price applies if you have a company with a valid EU VAT number or if you're based outside of EU. Non-EU buyer pays the import duty and tax as regulated by their local customs. Private buyers in EU are a subject to VAT. We would have to add and charge 24% VAT tax part from private buyers in EU.