Product Review - Redgum RGi120 Two-Channel Integrated Amplifier - January, 2000

David Wurtz

Redgum RGi120 Two-Channel Integrated Amplifier

120 Watts/Channel rms into 8 Ohms, both Channels Driven, 20 Hz - 20 kHz

THD: < 0.009%

S/N: 100 dB

Input Impedance: 10 kOhm

MFR: 0.8 Hz - 80 kHz  ±3 dB

Size: 3" H x 16 1/2" W x 13 1/2" D

Weight 17.5 pounds

MSRP: $2,095 (Australian), $1,200 (USA)

Redgum Audio, Factory 3/25 Clarice Road, Box Hill South, 3128 Melbourne, Australia; Phone 61-3-9897-1277; E-Mail [email protected]; Web


To date, it’s been difficult for audio purists to find products that meet their needs on all levels, including, for example a high quality sound coming from an aesthetically pleasing product manufactured in a locality of your choice. I mean, wouldn’t you rather buy a product that was designed, engineered, and built in your own country (Australia) and that could be pigeonholed with some of the best products around? WelI, I believe I’ve found it.

Welcome to the world of Redgum Audio, established 6 years ago by Ian Robinson in the suburbs of Melbourne, Australia. Ian’s goal after 30 years in the audio industry was to design and build a product “that was sonically pure and reliable”. Of course, most manufacturers have similar goals. Let's see if Ian has accomplished his.

There are 5 models in the Redgum range starting with the “entry level” model, a 60 watt Stereo Amp (with passive preamp) at $A1395, all the way up to the 300 watt Monoblocks (2 of with a passive preamp) at $A10,995.

The Features

All Redgum amplifiers boast the same excellent features and technological advancements, such as

  • Ultra high current power supply and output’s.

  • Gold plated input and output connectors.

  • Minimal signal processing and shortened circuit paths.

  • A solid Redgum (a natural Australian hardwood) fascia and removable key style on/off switch. (great if you leave the house and don’t want the kids to play with your gear).

  • A “No blown fuse” design with short circuited output protection. Ian’s theory is that, “The amp must always work” and proven with a 7 year warranty.

  • All components and wiring have been silver soldered. No more dry joints (crimps).

  • Conductive plastic tracked potentiometers.

  • Innovative P-channel MOSFET design which doesn’t exhibit the wear and tear of valves (tubes) or the negative temperature coefficient of bi-polar transistors. (MOSFETs conduct less current when they heat up, while bipolars conduct more, which can sometimes cause "runaway" problems if the bipolar circuitry is not protected well enough.)

  • Low noise toroidal transformer and 18,800 µF power supply filtering.

  • Each unit is individually hand built, “burn-in tested” and has its own specification report.

  • You can buy direct from the factory in Australia - They ship by UPS to any destination in the world within a few days and most major cities within 48 hours.

  • Redgum Audio offers a full money back guarantee if you are not completely satisfied - however, freight costs BOTH WAYS must be paid by the customer.

This review targets the “second up” model in the range, the RGi120, which is Redgum’s 120-watt/ch power amp (with built-in passive preamp) at a RRP of $A2095.

On initial inspection the RGi120 demonstrated that it has a very Australian look (wood front instead of metal) with the solid Redgum fascia and key style on/off switch. It stands 2 rack units high and has a high quality build (which was fully confirmed after opening up the covers) for its overall weight of 8 kilos. The only controls on the front of the unit are three large black knobs which are the dual mono volume controls and an input function switch. As for the dual mono volume controls, I honestly, at first, found them a bit annoying. Upon thinking back though, I have at times wished for something like this, especially when both channel levels are slightly uneven and I wanted to correct it. Let’s face it, a balance control is just an extra burden in the circuit to degrade the sound quality. So, the end result is that I might even learn to like using two knobs instead of one. The markings (CD, VCR, etc.) on the function switch are in a straight line across the top of the knob. I would have preferred them to be more accurately spaced in a crescent around the knob. On the back I found gold plated input and output connectors that were very sturdy when I terminated the cables.

Upon switching it on for the first time I heard a slight thump, so I turned off. Approximately 10 seconds later I noticed the speakers thump even louder. What? Was there something wrong I thought? I consulted the additional info to find that this has been purposefully left alone because, in the designers experience (30 years servicing such products), speaker “de-thump” relays cause problems (in particular, the metal contacts) and one of this amp’s design philosophy is not to break down. Other notable internal features include multi-contact conductive plastic tracked volume potentiometers. Plastic I hear you say, well in actual fact, conductive plastic “pots” tend to be more reliable and have lower distortion figures than their carbon counterparts, albeit at 10 times the price! Maybe that’s why other manufacturers seldom use them? There is a mini cooling fan, which is thermostatically controlled and whisper quiet. Lastly, I couldn’t help myself and had to short the speaker outputs to test the short circuit protection, and, as expected, nothing happened (except that my heart rate got back to normal).

The Sound

I connected the RGi120 into my system, namely, a Sony CDP-C545 CD player and JBL 4410 Studio Monitors. I first played one of my favorite CDs by a great Oz band “The Rockmelons” called “Form One Planet”. Wow, the sound stage widened to a breadth and depth I’ve seldom experienced from any amplifier . . . and the stereo separation! I know a lot of amplifier companies that boast extremely high stereo separation figures, but I really noticed it in this baby! Digital effects, hi-hats, cymbals, bells and whistles on the album made the room come alive, almost to the point of wondering where the walls had gone! I was continuously looking over my shoulder and hearing “bits” in the music that I’ve not heard before. It was almost like surround sound with 2 speakers. I pulled out another Australian album with a high quality production by Midnight Oil. In particular, the tune “One Country” with Peter Garrett’s powerful voice, Bones Hillman’s haunting vocal melodies, and Rob Hirst’s perfectly natural sounding kick drum. I was genuinely drawn into the song. The Redgum excelled in all facets of the reproduction. Deep, accurate, and well rounded bass, life-like vocal reproduction and a sweet sweet top-end.

I also spent time listening to classical music. Of particular note was Beethoven’s “Piano Concerto No. 5 in E flat Major”. Now there was no doubt in my mind that the RGi120 had excellent dynamics/ transients and WOW, that channel separation (didn’t I mention this earlier?) All in all, a superb reproduction of the source.

I thought the ultimate test would be to see how it handled a whole bunch of tough-load things going on at once (hard rock /metal). I chose Metalica’s “Black” album and particularly the song “Enter Sandman”. It has lots and lots of deep bass with Lars Ulrich’s deep electronic drum samples and those “huge sounding” guitars. Bob Rock has done an exceptional job with the production on this album. Bass reproduction was excellent going all the way down and never losing its body. The most notable feature though, was the snare drum. I’ve not previously realized how sharp it is (proof again of the excellent transients and high slew rate of the amp). It stood out clearly, nearly ripping both my ears off. The vocals again sat nicely on top of the music and most importantly in the center of the sound stage, the Redgum handled it all. I wound up both volume controls way above comfortable listening levels, admittedly there wasn’t much adjustment left. There was no sign of the amp distorting at all. It is a very powerful but clean 120 watts. This is probably due to the oversized power supply and outputs, which will handle transients of up-to 240 watts. The power supply has a total capacitance of 18,800 µF, and the DC voltage across the caps is 63.6 Volts, totalling energy storage of 76 joules. I also feel this is confirmed according to the amps individual test report. It possessed a pre 0.01% THD (Total Harmonic Distortion) with an rms output of 147 watts left or right channel driven and 121 watts with both channels driven.


Redgum Audio holds an interesting place as one of the few amplifier manufacturers in an Australian market, flooded by American units offering more bang for the buck. The RGi120 has the panache, power, electronic stability, and longevity to be classed with the best around, and best of all “Australian Made”. It took everything I threw at it, and gave me more back, which kept continually surprising me as I thought I had heard “all the little bits in the music” of most of my CDs. For a shade under $A2100 I believe there is not much around that could claim to be a better all-round option.

I can’t wait for a five-channel version! The only unfortunate thing for me is I’ll have to send it back, but maybe I’ll send him a check instead?

- David Wurtz -

© Copyright 2000 Secrets of Home Theater & High Fidelity
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