You are here

Crane Song Syren

Valve Microphone Preamplifier
By Bob Thomas

Can you resist the sound of this Syren’s song?

The recent arrival of the Dave Hill-designed Crane Song Syren microphone/DI preamplifier brings a welcome new addition to the small roster of valve-based 500-series preamps. Being from the design pen of Dave Hill, you’d have a right to expect it to be technically interesting, and it certainly doesn’t disappoint in that regard.

The front panel carries the usual polarity-invert, phantom, mic/DI, high-pass filter and pad switches. You might be pleasantly surprised by the three-position pad, though, with its 0, -15 and -25 dB positions, but slightly less impressed by the absence of an OD LED to indicate the presence of phantom power when that’s switched on. Alongside its input gain control, the Syren also features an output gain as well as a Color switch that, in its open position, cuts off the negative feedback to the second stage of the preamp’s solitary valve.

At the Syren’s heart lies a 12AX7B (ECC83) dual-triode valve that’s fed by a Lundahl LL1576 high-quality microphone input transformer, or directly from the front-panel instrument input. The basic topology is reminiscent of early 12AX7-based valve preamps such as that found in the 1955 Fender 5E1 Champ guitar amp. As in the old Champ, the input signal drives the first of the 12AX7’s two triode stages and the output of that, governed by the input gain control, drives the second triode. Instead of the 5E1’s 6V6 output valve, the second triode — via the 90Hz 24dB/octave high-pass filter and the output gain control — drives a solid-state stage, the output of which is balanced by another very high-quality Lundahl transformer, the LL1585. Each of the two gain controls has an associated red OD LED that lights at -6dB before the onset of valve compression or overload.

Crane Song SyrenThe overall circuit setup means that you have the opportunity to work with the Syren’s gain staging at five separate points in the circuit: the output level of your source, the three-position pad in front of the input transformer, the inter-triode input gain, the output gain of the second triode, in front of the output stage and transformer, and any input trim on the console, recorder or DAW to which you’re sending the Syren’s output. Changing the levels going into its internal stages will vary the sound character coming from the Syren, on top of which you’ve got the Color switch to experiment with, by switching between the more accurate sound that you’ll get with negative feedback, and the warmer and, I like to think, somewhat wilder sound that you get without it.

If there ever was a unit where eyes and ears are the only sensible setup tools, the Crane Song Syren is it. The input ‘overload’ LED actually sits before the input gain control, so if it lights up (and you don’t like what you’re hearing) you’ll have to either use the pad and/or reduce the level of the source. The output OD LED is positioned in front of the output gain control so, if you want to drop the level there, you’ll need to use the input gain.

Once you’ve got your gain staging in place, you can start experimenting with negative feedback, which will not only change the harmonic content and possibly the harmonic distortion of the output, but will also change the interaction between the two valve stages. The output impedance of the source feeding the Syren’s input transformer, the level and frequency content of the input signal and the gain settings also affect the inter-stage interaction — so you really have to use your ears to find the sound that you want. Once you’ve got used to how these variations sound, you’ll find just how usable the Syren can be and how much it can add character to microphone and line-level sources. The Syren also makes a killer electric guitar and bass preamp, especially with every stage from input to output being pushed quite hard.

Working with the Syren is entirely intuitive, and the results more than justify its price tag. Probably the only downside is that recreating those sounds is not a precise science. Thankfully the process of discovery is an extremely satisfying experience! The Syren is not exactly what you’d describe as uncoloured, yet it does combine all the warmth and depth that you’d expect to hear in a valve preamp with an impressive amount of detail, courtesy of its 6Hz to 80kHz bandwidth. While I wouldn’t personally like to rely on a Crane Song Syren as my one and only mic preamp, it does have a unique quality that I’ll be sorry to lose when it leaves. If you’re looking for a mic preamp that can add a ‘certain something’, you really should take a listen to this Syren’s song. Bob Thomas

Published March 2015