Yes, the company is called Rainbow. Make your peace with it. In high-end car audio circles there are some eclectic brands that elect to remain modestly sized and out of the mainstream spotlight, and German manufacturer Rainbow is a perfect case study. “What’s its name again?” is something I hear ceaselessly. Yet this astute little prodigy has been designing, developing and (unlike many wholesalers) actually manufacturing its own high quality audio components for decades now, in the process firmly anchoring itself within the upper echelons of car audio worldwide.
So a few years back, Rainbow’s head designer Paul Jelko was faced with a conundrum. What to actually design next? The Rainbow stable already held its bases covered with the entry-level ‘Experience’ range, and above that what are arguably world’s best component speakers in the mighty ‘Reference’ series. What to do next when looking for a new challenge?
The decision was taken to develop a brand new range that would sit pretty much dead centre of the two — and when I say ‘develop’ I don’t just mean a quick rehash of existing equipment with fresh new stickers. Those familiar with Rainbow will appreciate that this innovative master doesn’t shy away from a challenge, and Rainbow developed a completely new range, utilising afore-learned technologies and materials from ranges residing far above it. And the end result, named ‘Germanium’, stands head and shoulders above competing lines not only at its given market position but far higher too.
The Germanium range features an abundance of components from component sets and subwoofers through to amplifiers. Speakerwise there are various sizes and flavours available in passive, semi-active or active configurations. Here we’ve opted to examine the most common of these configurations — the almost too straightforward two-way passive GL-C6.2 component set.
The deceptively plain 166mm GL-W6 driver is not quite as elementary as first appearances suggest. Its cone has a fine-woven paper-pulp base, but reinforcing this and providing exceptional damping characteristics is a blackened aluminium layer molecularly bonded with the lower diaphragm, the combination providing an exceptional Young’s Modulus without saddling it with excessive weight. This allows the aggregate cone to maintain its structural integrity even under the most challenging of kinetic demands. The centre of the cone is home to a carefully-shaped dust cap, which not only combats resonance but also serves to push the speaker’s output azimuth well forward of the piston face.
Not to be outshone by the exotic cone, the top suspension features a specifically profiled butyl rubber ‘dual-M’ surround. These twin parabolic curves flex and move, varying distances depending on the drive’s linear movement, thus ensuring everything is kept within the strictest of alignments. Assisting this and forming the lower portion of the suspension is a non-progressive polycotton spider which, along with the flux, oversees carefully the linear movement of the motor within, and provides a sensitivity of 90dB.
Unsurprisingly it’s not just any old motor either; far from it. Rainbow worked meticulously on the motor itself, the result being a 32mm Kapton former wrapped with a four-ohm copper voice coil, tuned by dual copper shorting rings. The first of these is embedded within the pole piece; the second has been placed within the confines of the magnet. Space and public interest won’t permit me to delve too deeply into the intricacies of this system — suffice to say that these rings work to rectify the various issues posed by closed loops of electrical currents within the conductor, sometimes known as eddy or Foucault currents. These rings alter the magnetic field via Faraday’s law of induction, the result being a lower inductance and far less overall distortion.
Turning the unit over reveals a magnetically inert die-cast aluminium frame, complete with four pairs of aerodynamically transparent webs which serve to hold the ferrite magnet firmly in place. Peppered liberally around the perimeter are numerous intake vents which allow for titanic gusts of cool air to be inhaled with each reciprocal movement. From there said zephyr travels over the voice coil and former, before being expelled via a 10mm pole vent, bell mouthed to ensure that no fluid dynamics issues rear their ugly head. This efficient cooling system allows the motor a continuous power handling of 120 watts. Likewise the suspension, despite having a very low fluid resonant frequency, is robust enough to handle the odd peak burst of double that.
The motor also enjoys a high Q, making it ideal for automotive locales such as doors. Palladium-plated terminals are located upon one side between the web fingers, adjoining silver-coated conductors leading to the coil.
Rainbow has cut no corners pertaining to the design of the GL-T26 tweeters either, utilising ideologies from numerous high-end design concepts to achieve its goal. The 26mm diaphragm is constructed from a base of silk that’s been coated with a clandestine chemical coating, and the dome profile optimally designed to provide superb off-axis response. Even the grille protecting this hasn’t escaped Rainbow’s attention, being designed with hexagonal perforations in order to remain as transparent as possible. Living beneath the dome is a motor featuring a similar copper shorting ring to the midrange which works on conjunction with the four-ohm voice coil wrapped tightly upon a thermally efficient aluminium former. Enshrouding this is a fastidiously designed neodymium magnet whose physical shape and position are such that it’s able to impress a substantial influence over the voice coil.
The die-cast aluminium rear housing holding all this is no less the marvel. Back waves emanating from the diaphragm and their inherent turbulence can create serious issues for a tweeter attempting to reciprocate many thousands of times per second without distortion. Each reciprocal movement sees this cavitation create a choppy mess of compression and rarefaction waves that the proceeding cycle must withstand and overcome. In order to allay this, Rainbow designed an elaborate labyrinth within the backend, an almost aperiodic-like chamber lined with a specially-designed synthetic material. This labyrinth chamber hastily diminishes the energy of back waves, keeping them away from the underside of the dome.
Likewise the cooling system is also a tad departed from the norm, with Rainbow electing to omit the standard ferro-fluid cooling method-ology and instead run with an advanced fully-ventilated multiple-pole air-cooling system that allows for a continuous power handling of 120 watts. This aspect along with the suspension is conducive to an exceptionally unrestricted movement leading to more natural sound, deeper resonant frequency and lower F3 point. These enable the driver to blend seamlessly with its bigger sibling.
Capping the deal
Speaking of seamlessly conjoining driver output, this is the domain of the crossovers. Beautifully handcrafted, they come housed in robust ABS cases finished with smoked black Perspex covers. Beneath the cover is an interior full of high quality goodies, such as MOX resistors and Mundorf capacitors, the latter working in conjunction with the low resistance air-core coils providing second order 12dB slopes centred on 2200Hz. Unlike many mid-range crossovers these units also feature phase correction, sometimes referred to as a impedance linearisation circuit; these help to align the drivers electrically by altering the phase at certain points in order to ensure the sound from both arrives at to the listener simultaneously. Testament to Rainbow knowing a thing or two about crossover design is the quintuple point switching system allowing you to tune the tweeter attenuation perfectly to suit your application. And if you’re guilty of getting a little overzealous with the volume at times, rest assured Rainbow has incorporated twin protective circuits in the form of a PTC fuse, with a halogen bulb which will actually light up if you’re starting to encroach upon the circuit.
Fitting & listening
Installing the full component set is quite straightforward thanks to the modest mounting depth of 65mm and 20mm respectively, dimensions that’ll see them go happily into most modern cars. With components mounted and running in nicely via correlated pink noise, I rummaged through my music collection accumulating all sort of titles. I was super keen to get into these drivers given my experience with Rainbow equipment hitherto.
Within audio circles Rainbow has quite the reputation for sounding awesome straight out of the box with very little ado, and the Germaniums proved to extend this trend and then some. In reality when talking high-end speakers you hopefully don’t get bad ’uns, so to speak, nevertheless some do consume entire days before they sound good. Not these boys, though. Right from the get-go they’re quite something to experience.
The midranges are very stout in their aural reproduction, punching not only with impressive accuracy but with real definition right down into the lower midbass regions, validating that combination of cone material and suspension design. The higher orders of sound are likewise remarkably precise. Whether you’re playing the normally shrill sound of violins, through to the crash of cymbals, the tweeters remain clinical, smooth and crystal-clear to the point — they sound more akin to the real instrument than a mere mechanical diaphragm. The crossover is equally well-implemented, guaranteeing that the drivers transition seamlessly in order to provide a harmoniously clean reproduction across the entire audible portion of their specified 39Hz–30kHz frequency range. The overall linearity of the sound is simply beyond reproach.
Coming into land, then. Don’t be put off by the name — rocking up to your local audio competition proudly proclaiming your car is full of Rainbows might generate the odd snicker from folk less well informed. Trust me, though, when I promise you’ll have the last laugh. For one can’t happily return to audio mediocrity once speakers of this quality have been auditioned. Rainbow has long had a reputation for upstaging its competition — and the Germanium components highlight perfectly why this reputation is so well deserved.
Rainbow Germanium GL-C6.2 incar component speakers
TYPE: 6.5-inch & 1-inch component set
CONTINUOUS POWER HANDLING: 120 watts continuous, 180 watts maximum
FREQUENCY RESPONSE: 39Hz–30,000Hz
IMPEDANCE: 4 ohm midrange / 4 ohm tweeter