New Gear Review: Radial Twin Servo 500 Mic Preamp

The new Twin Servo 500 from Radial Engineering brings the astonishingly hi-fi performance of the Jensen Twin Servo to a compact 500-series package.

Those of you lucky enough to know what a Jensen Twin Servo 990 or John Hardy preamp sounds like will probably be very exited to hear about the new Twin Servo 500 series microphone preamp from Radial.

My first encounter with the original Jensen Twin Servo 990 was back at RPM Studios in NYC when I was just starting out. The Jensen was always the first choice when recording very quiet sound sources or anything that required a lot of gain without distortion.

Although I know it was the go-to tool for so many great engineers in these situations, I never understood why it performed so well with these kind of sources until recently, when I had the opportunity to test drive a Twin Servo from Radial.

In Use

The basic theory behind the original Jensen 990 Twin Servo is that there are two Op Amps that share the work of amplification. This means that each Op Amp is “working” half as much, and therefore, results in a lower noise floor and half the distortion. I learned that Radial is faithfully reproducing the Twin Servo preamp in the 500 series package. Radial Engineering acquired Jensen in 2014, so this is not just an attempt at replicating or reverse-engineering the original design—it is the original design, updated and ported over to a new, compact format.

I figured the only real way to test this guy was to A/B it with an original. So, using a Radial Pro MS2 mic splitter, I sent the signal from a Neuman U87 to both a Jensen 990 Twin Servo and the new Radial Jensen Twin Servo. I recorded everything from vocals, to cymbals, to snares, to a glock (enspiel). I have included samples of these here so you can hear them for yourself.

The difference was actually a little bit surprising. I was not expecting too much of a difference, but as you can hear, there is. At the same settings, the new Radial Jensen Twin Servo seemed crisper, sharper clearer and louder to my ear.

To make things more fair, I have level-matched the examples here by normalizing the audio files to make the subtle difference in tone apparent I am going to attribute this difference to the fact that the Jensen 990 Twin Servo I had access to was about thirty years old, and could be in need of service. Who knows if an off-the-shelf Jensen might have sounded more identical? Either way, I preferred the accuracy of the new Radial Twin Servo.

Click here and fire up some good headphones or speakers if you’d like to download the full resolution WAV files and hear the subtle difference for yourself.

Cutaway view of an original Jensen Twin Servo, a design now acquired by Radial.

Features

One of the improvements Radial has made over the original is the size of the gain pot. While this is a small step up, it is worth noting.

It is much nicer to grab a big knob (double entendre intended / #AudioNerdHumor). Another merit of this reincarnation is putting it into the 500 series format—a great idea.

Previously, the Jensen 990 twin servo had its own proprietary 1RU rack and power supply, topping out at four slots. Now, depending on what 500 series chassis you have, you can have half a console’s worth of them.

Another view of the Twin Servo 500.

The last positive worth mentioning is that, like all Radial products, this thing seems to be built like a tank! I remember my first time picking up a Radial Pro DI and being comforted by the shear weight of the thing.

The only downside that I can see thus far is the price tag. Not that it’s unreasonable for the product, it’s just that at $999 it seems to be on par with the cost of a vintage Jensen 990 Twin Servo, which as I have found out, can be worse than this updated version.

I am afraid that people will play the vintage gear “Price Is Right” game show; and buy a piece of gear for the name, not for the way it sounds. If Radial can find a way to drop the price by just $100 or $200, I think they would have as many people hooked as Frank Lucas did with his Blue Magic.

Needless to say, I am thrilled with what Radial has done here. Although 99% of the time I will reach for a Neve or tube preamp, there are those occasions, namely on strings, soft vocals, or any kind of room mic, when I want to be able to crank up the gain and not hear caps or op amps hissing away.

Usually I’m at the mercy of whatever the studio is equipped with, and the assistant engineer will point to something like an API, which is fine (and I’ll probably get shot for saying this), but it’s not really as good as a Twin Servo in terms of headroom. If you’ve used them, you know, that signature crackle when you hit an API too hard.

I think what I am trying to say, is that every studio should own at least a pair of these. They are an indispensable piece of gear, and a perfect compliment to a rack full of vibey Neve, Telefunken, and Helios pres. I’m glad to see that Radial has taken the helm on recreating this one. They’ve knocked it out of the park—again.

Nic Hard is an audio engineer who has worked with Snarky Puppy, The Bravery, Joey Ramone, Jack Bruce, Tito Puente, Eagle Eye Cherry, Flava Flav, Jesse Malin and many more.

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