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Rainbow iPaul 4.300


Four channel amplifier with high current MOSFET switching power supply. Two Ohm stable, also usable bridged or in Tri-mode. Protection circuits for thermal, DC, short circuit or under-impedance fault conditions. Soft-start muting circuit with one second delay to avoid turn-on thumps. Palladium plated terminals for power and speaker wires. Surface Mount (SMD) circuit board. Five metre remote cable with two-knob remote box included for use in control port, offering remote infinitely variable phase and gain control. Fixings and plastic silvery feet included, as well as plastic screw-terminal moulding for use with “Peak Performance Coupling Module” yet to be released peak power doubler accessory unit used to take advantage of the large capacitor bank already within the amplifier. Other accessories include a thermostat and fan module. You can have a remote temperature gauge on your dashboard and control a fan. Gain and crossover cut off frequency are set by use of potentiometers only revealed by removing a top panel with the included Allen key.

- Class AB
- 4 x 90w RMS @ 4 Ohms
- 4 x 140w RMS @ 2 Ohms
- 2 x 270w RMS @ 4 Ohms bridged
- Aluminium heatsink with shiny black finish to main panels
- 25mm sq. power terminals and 10mm sq. speaker connections on grub screw bare wire socket connection
-RCA inputs for four channels plus RCA throughput sockets
- 0/6/12dB Bass Boost @ 45Hz by switch
- Input sensitivity: 250mV to 0.6V
- Illuminated Rainbow logo in blue on top
- Stereo, Mono & Trimode operation
- Frequency response 10Hz to 35kHz
- Signal to Noise Ratio >95dBA weighting
- Phase shift 0 to 180 degrees for rear use only
- High Pass/Subsonic Filter (front) 15Hz to 5kHz @ 12dB per octave
- High Pass/Subsonic Filter (rear) 15Hz to 500Hz @ 12dB per octave
- Low Pass Filter (rear) 50Hz to 5kHz
- Band Pass Filter (rear) 15Hz to 5kHz
- Fuse Rating 30A x2
- HxWxD(mm) 60 x 415 x 250mm

Review by Adam Rayner

Like the old Apple iMac spawning a host of flatteringly similarly-styled items in the electronics market, the iPod is also breeding a spawn of flatteringly styled items from the iRobot Roomba robotic vacuum cleaner all the way to this startlingly sexy-looking slab of technology. It adds Teutonic gravitas to the whole thing. It comes in a posh box which itself is stylish and as you open it there is a piece of black card that simply has “Say hello” printed on it in white. The English is seen as cooler as it should otherwise have “Sprach Guten Tag” or “Dit Bonjour” printed there. You lift the card and see a black velvet bag with iPaul emblazoned upon it. Take the thing out, noting the neat baggie of fixings and feet and the dual UK-German manual in another bag and you have a solid slab of blackness, broken in the middle only by a round and rather cool Rainbow logo. The terminals are all simple crosshead screwdriver types and are at a useful angle so as to make installation a lot easier. There is a panel on the top that you remove to set the crossover frequencies. These look at first to be simple switch-set primitive types but are in fact as sophisticated as any I have seen in car use. They can be used as subsonic, bandpass or else as simple high and lowpass crossovers. Their curves are clearly printed in the manual for use by the experts.

There are inputs for four channels as well as a stereo output. You get a small extra pluggy thing which I at first assumed was for use as a high level speaker-wire input. It isn't. Rather, it is for adding a cunning accessory which is as yet unclear as to what's in it but I gather that the accessory (as yet not sold in the UK) takes advantage of the very large bank of capacitors that live inside the amplifier. Once hooked in line this is able to double peak output at times of heavy spankage. Sounds like a cool thing. An amplifier you can accessorise. There is another Molex connector so I thought THIS was the high level connector. Wrong again, it is for use with a thermocouple. So you can have an amplifier temperature gauge on your dash as well as control a fan from the front of the car. The box also has a long old phone wire (5m) and a box on the end with two knobs for control of the phase of the rear channels (used for bass phase matching and only ever found on posh amps both home or car) and also a simple gain control as a classic bass level doofer. Talking of classic, there is also a six or twelve dB switchable bass boost centred around 45Hz for use by the bass hedz amongst us.

It really gives off some sense of both classy engineering and a sort of 21st Century now-ness. It'll look cool as a cucumber for ages yet, with the iPhone looking just like it. Or is that the other way around? Either way it looks fabulous and deeply desirable as well as being a well made thing. All that remained was to give it a good listen.

I chose to use it bridged to see just how powerful it was into a set of 'known good' high power full range speakers, although I did of course give all the knobs a twiddle and switches a flick to see how well the crossovers' 12dB slopes coped with excluding the frequencies you don't want when you don't want them.

I found that the crossovers were indeed potent and easy to use, having them sealed up behind a brushed ally panel you need to Allen-wrench undone to open makes for less messing about once you have settled on your uses of these controls.

The sound was open and sweet with great power and authority. The tinkliest of highs came through and I found myself getting analytical about the headunit rather than the amp, which is always a good sign that it's a good one, allowing all the other components in the sound chain to do their thing without detracting from them. The ease of use is high too once you have read the manual and got a grip of the variations of the settings on the switches.

I played an orchestral item – the music from Star Wars on a 24 Bit CD as well as some of the madder recordings on the Boom Tube bass CD that I love so. The Revenge of the Pink Boom in particular as it has triangles and daft levels of lows. The bass booster worked a treat although a knob would make this more subtle. Perhaps rainbow realise that 'bass boost' and 'subtle' do not go together! It works well although the six dB was far more sensible than the 12dB when you are playing with a daft recording in the first place. I tried the remote gain and phase controls in the box. They have a super-bright blue LED that is blinding to look at directly, so it needs mounting where it won't be on-axis to your eyeballs.

A lovely clean amp with bags of power, great value for money and a keen sound as well as huge versatility in application. It has brethren, too. The two channel 2.400 costs £249.99 and the DM2000 is a 1 kilowatt bass monster in class D for £399.99,

Humble pie slice time. I was dead rude about another review elsewhere of this amp, which was childish and parochial of me. I do apologise to those involved and state for the record that I do believe it won its review in the magazine in question entirely on its merits and as a nod in the direction of contrition, will be using the amplifier to test no fewer than around twenty pairs of component speakers from £120 to £1,000 in the 6.5 inch size.

Overall 9.0
Sound Quality 8
Power Output 9
Features 10
Build Quality 9
Value For Money 9


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