REVIEW: Rupert Neve Designs 5254 diode bridge compressor

Is the new compressor from Rupert Neve Designs destined to become a future classic? Music technology author and lecturer Stephen Bennett finds out…

What is it?
A new take on Rupert Neve Designs’ diode bridge compressors.

What’s great?
Excellent engineering. Controls that inspire confidence. Great metering. The sound, the sound!

What’s not?
It would have been useful if the side-chain filter went up a bit higher.

The bottom line
Rupert Neve designs continue the tradition of producing beautifully built, audio processors with a sonic signature that will stay with you for a lifetime.

The diode bridge compressor is something of an undiscovered country in engineering circles. While processors using Field Effect Transistors (FET), optical or vari-mu technology are common, those based on diode bridge less so. Many of the compressors found in studios using this technology will bear the Neve name—but not all are made by Mr Neve’s company. The unit under review here is the Rupert Neve Designs 5254 and, as the name suggests, it is manufactured by the venerable engineer’s own firm. We won’t go into the reasons why there are two companies that share the Neve name—but suffice it to say that Rupert Neve’s current thinking around compressor design runs through the 5254. It’s based on Neve’s 1970s’ 2254 compressor and shares DNA with the company’s Shelford channel.

Build quality
The 5254 is a stereo 1U 19” compressor with in-bult power supply. It’s a Class-A, all-analog affair, with custom Rupert Neve Designs transformers on the inputs and outputs. Rear panel connections are via XLR and XLR/TRS, while the side chain connections are on Neutrik TRS. A power switch and ground lift are also located here. The front panel is split into two sections for left and right compressors and both sides sport ‘traditional’ Threshold and Ratio potentiometers—the latter running from 1:5:1 to 8:1.

The ‘Timing’ knob sets the Attack and Release controls simultaneously, running from Fast to Slow—but their actual values depend on the ratio settings and the enclosed manual details typical figures for each of these. The Attack and Release parameters can be further modified by depressing the Fast button—which has the effect of ‘speeding up’ the time constants by 70%—and there’s also a programme-dependent Auto setting. The High Pass Filter (HPF) is a 12dB per octave Sallen-Key design, whose range—from 20Hz to 250Hz—helps reduce the effect of frequencies on the compression. This sits over a Side Chain button that routes the audio in and out of the compressor. A Blend knob controls the mix of compressed and dry signal for quick parallel processing.

Makeup gain is really important on this type of compressor, as the input signal feeding the diode bridge needs to be reduced by 40dB and made back up on the output for it to function successfully. I can confirm that the 5254 generates no extraneous noise in use, even at high gain settings. The centre section features two (signed!) illuminated VU meters that can display both output and gain reduction and with peak LEDs set to flash at 3dB below clipping, A ‘Comp in’ button that toggles both channels together and a stereo link button complete the front panel controls.

I don’t own an AMS Neve 33609 diode bridge compressor, but I do have a lot of audio processed through one, so I tried to set up the 5254 to emulate the 33906 with the same unprocessed recordings. I couldn’t really get there, which does suggest there are different technical decisions going on here—in fact, I felt that my Heritage Audio Successor stereo diode bridge compressor was closer in sound to the 5254 than the 33609. The way both the 5254 and Successor processed the audio is similar—you can really get the compressor pumping with very few undesirable artefacts, alongside a lovely, for want of a better word, ‘vintage’ tone. Yet, the 5254 has that almost indescribable sense of sonic ‘heft’ that comes equipment with this heritage. Drums, especially, benefit from being passed through the 5254, but the compressor adds a certain something that just makes things sound better whatever you process with it. The 5254 shouldn’t be considered as a replacement for other types of compressor though—it sounds and processes audio quite differently from my SSL-type, 1176 and LA2A compressors.

Daily use
While some of the rotary controls are switched, others have 31-step ‘detents’, so I had no real issues with reproducibility between sessions. As usual, the best way to set these controls is to use your ears anyway and not worry too much about the absolute values. Compared with my Heritage Audio Successor, the 5254 proved more flexible with its two sets of separate controls—you effectively get two mono compressors for the price. Otherwise, the 5254 was a joy to use and always sounded wonderful.

The Bottom Line
I’m not sure there is really such a thing as a ‘transparent’ compressor, but the 5254 certainly isn’t that. It’s one of those devices that make everything you run through it sound better. It adds weight and richness while remaining useful even at extreme settings. The diode bridge does something quite different to the audio than other compressor types and I suspect that if you add one of these to your studio, I’d quickly become an essential tool and permanent fixture.

Rupert Neve Designs 5254 Diode bridge Compressor is available now, priced at £2,749, $3,599 (excluding taxes).