Universal Audio 1176LN

Mono limiting amplifier

Universal Audio 1176LN Mono limiting amplifier

Review by George Shilling

It is over two years since I reviewed the Purple Audio MC76, an enhanced recreation of the Urei 1176LN, my absolute favourite desert-island compressor/limiter. Perhaps awakened by the continued demand for this design, the two sons of original designer, the late M.T. "Bill" Putnam, sprang into action to reissue the original model under its original brand name. And a pretty good job they appear to have made of it.

Every last detail has been faithfully reproduced: even the manual cover has been copied, including the textured paper. The spec-sheets make similar reading, with virtually every figure identical, and the circuit diagrams show a similar design, although they are no longer hand-drawn.

The front panel is black, recreating the look of the more favoured versions of the original 1176. The originals went through several revisions, designated A to G: this unit has been based on the D/E black-faced models. Later units replaced the Class A output stage with a Class AB push-pull stage, and the transformer input was replaced with a differential op-amp circuit.

All controls feel similar, the unit featuring wonderfully large Input and Output knobs, and Attack and Release pots, which are all smooth in operation, the Attack retaining its bypass click-off setting. This removes any compression, but leaves the gain controls active, turning the unit into a characterful line amplifier. The illuminated meter is similar in appearance to later Urei designs, with the re-created UA logo featured, and a recessed trim pot across the other side of the panel for re-calibrating zero. And old-fashioned radio-bands style pushbuttons all work exactly the same as on the originals, except that they feel a little stiff and 'new'. Ratios of 4:1, 8:1, 12:1 and 20:1 are available with the central row of buttons, and on the right are selections for meter: Gain Reduction mode, Output Level at +4 or +8, and by pressing the bottom button the unit is powered off.

Universal Audio 1176LN Mono limiting amplifier

The OFF legending had been mysteriously stickered with on/off symbols, no doubt to satisfy some pernickety modern safety rules. Although, talking of safety, upon removing the cover, I was surprised to see unshrouded bare wires on the mains connections - a nuisance for any service engineer. However, the approach is admirable: the circuit layout looks similar in every respect, with plug-in transistors inserted into sockets mounted on the board. On the rear panel are tag connectors, exactly like the original, with connections for signal and also remote metering, although I would imagine this to rarely be required. Apart from a fuse holding IEC mains socket, the only addition to the original design is a pair of XLR signal connectors. The previously available Model 301 bolt-on box attached to the tag strip to provide XLRs, but many owners made their own modifications and attached sockets directly to the case. The phono socket for stereo operation is retained. This is labelled 1176SA, and the stereo adapter must be connected between two units for stereo operation. The timing capacitors are in parallel, so doing this doubles the fastest speed of the Attack time, and stereo operation is fiddly to set up, especially between units of different vintage, due to differing transconductance in the FET. Perhaps the 1176SA circuitry could have been included inside the case, as with the Purple model.

In use the unit feels very much like one of the originals. I was fortunate to have the luxury of David Gilmour's Astoria studio, which boasts several original black faced and grey Haeco-badged 1176s examples for comparison, not to mention excellent monitoring for comparisons. The 1176 uses a FET as a variable resistor to control gain, (there are no valves here), and this is the main reason for its unique character. All units were slightly different, but the new model's Output gain pot was noticeably changed, with perhaps a slightly different value - I had to turn it further clockwise to match levels. However, in most other respects, operation was identical, and the sound was very similar, with perhaps a little extra clarity from the new unit. Vocals sounded wonderfully enhanced by this compressor, and in normal use it was hard to hear any difference between the new and old models.

Attack and Release characteristics seem to have been accurately retained, with an Attack range of 20 to 800ms and Release times of 50 to 1100ms. The only really obvious sonic difference was in overdrive mode - the legendary technique of pressing all four Ratio buttons in simultaneously to give a really over-the-top distorted compression. The character of the new unit in this situation was quite different from any of the older models, with much brighter and nastier distortion, and less warmth, especially on fast settings. By backing off the Release speed, a more similar sound could be achieved, but there was still an obvious difference, and although the older units may have been somewhat out of alignment, this was the sound I preferred.

The 1176LN sounds great, but the lower-priced Purple competitor is sonically very similar, and features many improvements over the original design. However, as a 'strictly authentic' official reissue with indisputable credentials, the UA is the box to have.

Reproduced with kind permission from Copyright ©

Visit George's website to find more great reviews.