RGi120ENR Integrated Amplifier
Dr. John Richardson
Ah, Australia. I don’t think there is any other country that captures the collective imagination and wonder of us Americans to a greater extent. Why the intrigue? Is it the unique flora and fauna? Or the lovely coasts encircling that mysterious interior known as the “outback”? Whatever the case, I’d wager that if you asked a representative group of Americans which country they’d like to live in (besides our own, of course), the majority would say Australia with nary a second thought.
We all know about koalas and kangaroos, but how many of us are familiar with another Aussie oddity, the red gum? As you might expect, it’s a tree. I hadn’t heard of it, so I decided to do a bit of fact finding. The red gum is a fascinating member of the eucalyptus family, tall and strong, which is found along rivers and in low lying areas. It can surpass 200 feet in height, live upwards of a millennium, and yields a lovely, but hard to work, reddish timber. In many ways, it reminds me of a cross between our cypress and redwood trees. On the darker side, the tree is also sometimes referred to as the “widow maker” because it can slough off large branches with no warning, much to the chagrin or terminal detriment of anyone resting in its shade.
I mention the unique red gum because it serves as the inspiration for an equally unique audio manufacturing company called REDGUM Audio, based just outside of Melbourne, in southern Australia. Founded in 1993 by a highly experienced audio technician and designer named Ian Robinson, REDGUM (the company) has quietly gone about manufacturing by hand a wide range of amps, preamps, digital source components, analog phono stages, speakers, and of course, integrated amplifiers. One thing that is unique to every electronic component in the lineup is that in some way or another, a genuine piece of red gum (the tree) is used as an integral part of the device. This approach, at least in my eyes, imbues all REDGUM products with an unusual sense of beauty and elegance. The pictures really don’t do these things justice; having a piece of REDGUM gear in one’s listening room is as much a feast for the eyes as the ears!
When I first got wind of reviewing a REDGUM product, I really didn’t know what to expect as I had never before heard of the company. I found out that I was to spend time listening to one of their integrated amplifiers, namely the RGi120ENR, which lists for $4300 usd here in the States. A bit of research indicated that this piece is REDGUM’s top of the line integrated offering.
Upon arrival of the box from Carl James (of North American seller USAHiFi), I must admit that I got just a teeny bit excited. As soon as I started delving into all of the cardboard, I quickly began to realize that something special was going on here. First, this thing was packaged to survive a nuclear holocaust, so it took me awhile just to get through the first two carefully nested boxes. I might as well have been unwrapping King Tut’s mummy. Upon opening the final box, I was greeted with several large white envelopes, one of which was labeled “to the reviewer.” Hmm, now this was getting interesting. Inside the envelope was a beautifully bound reviewer’s guide to REDGUM in general, containing everything one could possibly want to know about the company and its products. Also enclosed was a very nice and detailed user’s manual, whose inside back cover sported a complementary copy of Chesky Records’ Ultimate Demonstration Disc, presumably to be used for system setup and evaluation. This was some serious attention to detail, and the REDGUM integrated had by now garnered my full attention! Of course, if I had possibly missed something important, that would have been quickly corrected by REDGUM’s director of promotions, a certain Lindy Gerber. Now Ms. Lindy is a lady to be reckoned with, as she was immediately in touch with me, much like a protective mother hen, to ensure that all was well. Thanks to Lindy, I now felt very comfortable with the task before me, as I had a virtual helping hand right there in the listening room if I ever needed it, even though it was really half a world away. Apparently attentiveness not only to small details, but also to the customer’s needs is a big deal with this small Aussie company.
The technical aspects of the RGi120ENR are many, and were well covered in the owner's guide and manual. First, the amplifier is turned on with a key, much like one would use to start an automobile. Each key is unique to an amplifier, so this approach could serve as an effective theft deterrent, as well as thwart the shenanigans of unruly teenagers (I should know, as I possess two of the latter). Maybe a gimmick, but what the heck? I just kept life simple by leaving the key in the “ignition.” Another unusual feature are the fully dual mono volume pots. Maybe a pain to use, but REDGUM insists that this feature is paramount to achieving ultimate resolution and channel balance. With the enclosed remote control, I had no issues whatsoever, though manual use might require some practice. A final point of interest is the amplifier’s “Ultraflex” power supply, which specializes in supplying short bursts of power quickly to the load (i.e., speakers). As Ian Robinson points out, music is about the reproduction of transients, so we can think of constant RMS power as sort of a foundational baseline, but what really gets the music going is the ability of the power supply to go into overdrive and turn on a dime. In other words, what we need is a power supply that can immediately deliver the goods in terms of powering the speakers as required by the instantaneous demands of the music.
Speaking of power, REDGUM has a tendency to underrate the output of their amplifiers. For example, the RGi120ENR is rated as supplying 155 watts per channel RMS into an eight ohm load. Inside the manual, I found a test sheet for my specific amp that reported a continuous output into eight ohms of 169.74 watts per channel, with short bursts of nearly 280 watts per channel... Now that’s overkill. Did I also mention that all REDGUM amps are comfortable driving loads of 0.7 ohms continuously? We’re talking just shy of a dead short here, folks! I’m pleased to report that in all of my time with the RGi120ENR, I couldn’t even get it to heat up, much less stress it out. Even if I played it loud on a hot day, the sculpted heat sinks on the amp’s underbelly never got warmer than the room. My cat Sunshine, always looking for a warm place to perch in any season, did not like this amp.
Altogether, it’s easy to see that the hallmarks of REDGUM’s design philosophy are simplicity of design and overbuild; their literature even goes so far as to call their amplifiers nearly indestructible when faced with a tough load. Based on what I’ve seen, that’s probably not too much of a stretch.
Build quality is quite good. The volume control and source selection knobs are finely machined aluminum, the faceplate consists of a highly polished and well-finished plank of real red gum wood, and the whole affair rests on a massive sinusoidally sculpted heat sink. The chassis appears to be crafted of somewhat thin sheet metal (said to be 1/16 inch thick), the only hint of possible cheapness I could find. It is very nicely finished in a glossy black electroplated coating, however. Compared to my massive Threshold SA 3.5e amplifier, a stark symbol of a lost era of American industrial might, the REDGUM seems delicately graceful in an almost feminine sort of way.
Unless you are an absolute purist, I’d recommend springing for the remote control option that I mentioned earlier (available for an upcharge on all REDGUM integrateds). Upon closer observation, the selector knob on the RGi120ENR doesn’t actually turn, but rather serves as a sophisticated sensor for the remote control, which itself accesses some pretty fancy firmware implanted in the amp. Via the remote, the user can control both volume pots in tandem, or control each individually through the “balance” option. One can even even balance the two channels within 0.1 dB of one another with a single push of a button. Of course, source selection is also controlled using the remote, and I found the mute option very useful when cueing vinyl (do note that no REDGUM integrated has a built in phono stage, so users should be aware that the vinyl rig will require an outboard stage). The controller itself is of the thin credit card variety powered by a watch battery, but I found it intuitive and easy to use.
Finally, it’s time to delve into the real crux of the matter here: the sound.
For evaluation of the RGi120ENR, my system consisted of an Antelope Zodiac DAC receiving bits from a MAC Mini through a Sound Devices USBPre2 serving as a usb to S/PDIF converter. The analog output of the Zodiac DAC in turn fed one of the analog inputs of the amp. The REDGUM was used to power my Shahinian Compass speakers, while I made use of the integrated’s preamp out to send signal to my Shahinian Double Eagle subwoofer as powered by an external ODL HT-2 amplifier. All components were plugged into a Spiritual Audio VX-9 line conditioner.
My first listen to the RGi120ENR told me that good things were in store. In many cases, first impressions can tell me a lot about the disposition of a piece of audio gear; in this situation I was hit with a big, clear presentation of the music which immediately showed the way beyond mere enjoyable to actual realism. Through my speakers the REDGUM projected a sense of nearly limitless power and ease complemented with extreme clarity and rhythmic drive. Over time I never felt that these attributes diminished; in fact, they kept on refining themselves and drawing me closer into the listening experience. If I were to choose a single word to describe the experience of listening to the RGi120ENR, it would be “natural” in the sense that I was really getting closer than ever before to the live experience. No sense of editing, no prettying up the frame around the picture, just plain natural. It’s only when you get the good fortune to hear an amplifier like this that you begin to realize the colorations that are intentionally or unintentionally built into lesser components. Take my Threshold amplifier as an example.
To me, this work of art was representative of what good solid state sound should be: smooth and warm, yet detailed and powerful. Against the REDGUM, however, I noted immediately that the Threshold actually seemed to have a faint, but real, veil of warmth. Removing this layer of sweetness, as the RGi120ENR does, actually showed me the man-made nature of it; what I was hearing was pretty, but not necessarily absolutely realistic. In short, the REDGUM’s presentation was more immediate and representative of the real thing, a living interaction between musicians and their surroundings.
When getting down to specifics, I could have chosen nearly anything from my collection to illustrate the sonic characteristics of the REDGUM. Since it’s Australian by birth, I figured, then why not dig out some works by some favorite Aussie composers?
For those who don’t yet know, there’s a wonderful music label out there called ABC (Australia); in this case the ABC part stands for the Australian Broadcasting Company. This is a state-run operation that has, among other things, made a point of highlighting the works of many modern Australian composers, most of whom have received little or no recognition here in the states. If one were to think that Australia is an artistic wasteland, then one would be gravely mistaken. Through the ABC label (you have to dig around a bit to find them here in the U.S.), I’ve been introduced to the work of wonderful Aussie composers such as Carl Vine, Ross Edwards, Peter Sculthorpe, Nigel Westlake, and numerous others. Oh, and have I mentioned that my go-to online radio station for jazz is ABC Jazz (same operation), which highlights excellent traditional and contemporary jazz with almost no needless chatting? I even caught my kids this weekend listening to ABC’s Indie and Alternative rock channel.
A good place to jump into modern Australian music is through the works of Carl Vine. This artist has produced seven symphonies, six of which are available on a two CD set (Carl Vine, Complete Symphonies 1-6, ABC Classics). These are accessible, colorful pieces, some of which have been favorites of mine for well over 10 years. When I close my eyes and let my mind wander while listening to these symphonies, I conjure up visions of what the Australian outdoors must look like: wild mountains and deserts, waves crashing on rocky coasts or rolling onto tropical beaches, and technicolor sunsets. Vine’s symphonies shine with dense and complex scoring, which must make them a real treat to hear live. Unfortunately for those of us who have to enjoy them via recordings, the results can be muddy and confusing if one’s audio system isn’t fully up to the task. Fortunately for me, however, I was listening through the REDGUM RGi120ENR. Never have I heard Vine’s works shine so luminously and so clearly. Details I’d never heard before seemed to jump out of the fabric of the soundstage, and with depth of tone and timbre I haven’t experienced previously (and I do know these recordings quite well). Even though the music was presented with such clarity, I never had the feeling that the amplifier was over-analytical in its reproduction. In short, the performances sounded like music; nothing more and nothing less.
Another sonic smorgasbord is Ross Edwards’ compendium of compositions, also on ABC Classics, which includes Maninyas (a violin concerto), his Symphony Da Pacem Domine, and Yarrageh- Nocturne for Solo Percussion and Orchestra. All of these works are engaging and well worth hearing, but for demonstration purposes, Yarrageh is the one that stands out. The percussion soloist, Ian Cleworth, is heard alternating among several instruments, all on a darkened stage, according to the liner notes. The effect is quite breathtaking at times, with piano and orchestral sections ebbing and flowing while counterpointed against the tinkling of bells, triangle, marimba, and other instruments. Spatial cues and complex timbres are the order of the day here, and represent a real workout for an audio system. With the REDGUM integrated in the system, I’ve never heard this piece sound so real and engaging. Closing my eyes, or listening in the dark, I could easily picture the orchestra playing on the stage before me. Sonic veils be gone, this damn thing is addictive! Lots of air around instruments, and a wonderful sense of soundstage depth are what met my ears and kept me engaged again and again.
One final observation I’d like to mention is that the RGi120ENR likes to play loud. In fact, it begs the listener to turn up the volume. The manual mentions this and warns the user accordingly. I normally listen at fairly low levels, and I’m not usually tempted to crank up the volume. The REDGUM grabbed me and told me to “man up” in this regard- to get down and boogie. This was especially true with orchestral music, which as we all know, does like to be played at higher volumes. At one point, I think I had the walls shaking, and it was exhilarating! Fortunately, the wife and kids weren’t at home, and the cats had run for cover. My point here is that the RGi120ENR, at least with my ca. 90 dB efficient speakers, had huge excess power in reserve and gladly played loud with hitherto unknown abandon, clarity, and lack of distortion. Proceed at your own risk; this is one heck of an integrated amplifier and dangerously addictive!
I’d like to close out with a short interview I had with Ian Robinson, REDGUM’s founder and chief designer. Ian was happy to answer a few questions for me that I think give a bit more insight into REDGUM, its products, and its business philosophy. So here goes:
JR: You use MOSFETs as the output devices on all of your amps. Why this choice, and how do you feel about the infamous “MOSFET mist”? Myth or reality?
IR: The choice of MOSFETs was driven by several factors. I had a retail audio business for 30+ years, and during that time I also did a lot of audio repairs (over 18,000 documented!). A very high proportion of those repairs were shorted output transistors on solid state amplifiers. There were also many repairs on super-expensive valve amplifiers - the valve amplifiers were a particular worry. No two amplifiers were ever the same ... this included stereo pairs ... and a five year old valve amplifier was a 'very old' product. During this time I was also the Australian service agent for a well-known New Zealand MOSFET commercial power amplifier. I developed a great respect for these almost indestructible amplifiers, particularly when one of a bank of 10 of them was booked in for service after operating in one of Melbourne's top-end night clubs for a number of years with one (yes, ONE!) channel operating into short circuit continuously since the installation!!!. So, it was 'no' to transistors, and definitely 'NO' to valves - MOSFETS are looking pretty good about now.
As to the 'MOSFET mist' (a term I had not heard until you asked) ... a quick Google leads me to believe it is based on two factors. The very first-designed MOSFET amplifiers were notoriously unstable and tended to oscillate with very little prompting. As a 'quick fix' to this design issue, a few of the early manufacturers installed a small choke in the speaker line. This certainly stopped the oscillation, but had the downside of 'dulling the sparkle' . The second factor was purely driven by marketing with manufacturers NOT using MOSFETS quickly jumping on the bandwagon implying that all MOSFETs had a long-term, irrecoverable problem.
JR: What was your impetus for starting REDGUM Audio?
IR: It happened as a result of this conversation in the late 1980s. I was in my retail store inspecting the latest amplifier from a well-known and loved English manufacturer and I commented "This is just a plastic lunch-box with $5.00 worth on components in it, and they want me to sell it for $1100.00! Surely it can be done better than that", and one of my staff members called me on it ... "Well, do it!"!
JR: I love the clarity, resolution, and musicality of the RGi120ENR. Is there a key "secret ingredient", or is this due to a combination of factors?
IR: The main 'secret ingredient' is developing the circuit to be stable, without the dreaded choke - hence no 'MOSFET-mist'!
Also during development, every component was 'goldilocks'ed' and after each change, a variety of musical styles were tested on a variety of speaker systems. No component was accepted until it proved to be an improvement IN ALL CIRCUMSTANCES. As you can imagine, this took some time, and our first REDGUM amplifier was not released for almost 6 years!
As to the musicality, our yardstick is NOT other amplifiers, but live, un-amplified real instruments.
JR: In your opinion, should an amplifier design be simpler or more complicated to make great music?
IR: Amplifiers are not particularly complicated electronics. A simple design, executed well, is, in my opinion the best option.
JR: Many thanks, Ian, to both you and Lindy for making this review happen!
In my cheap bastard’s world, $4300 (usd) is a lot to consider spending on a single audio component. However, in the case of the REDGUM RGi120ENR, the buyer is getting a powerful (155 wpc), neutral, resolving, and highly musical power amplifier coupled with a top-notch passive preamplifier with a sophisticated remote. Now that sum of money seems a bit more palatable. The REDGUM also looks spectacular with its shiny wooden faceplate and sculpted heatsinks, so much so that the significant other will probably be swayed by its elegant, artistic appearance, if not its sound. Well, I think the sound will help too.
Redgum warrants the amp for a full 7 years!
Audio reviewers by definition live constantly on the audiophile merry-go-round. Unfortunately, so do most audiophiles, and many want off... You get uncomfortably dizzy after awhile. I see the RGi120ENR as a perfect way to get out of the audio rat race and not look back, at least not for a very long time. As Ian Robinson puts it, it’s the kind of amp that should “see one out.” It really is that good. Crikey, just find a way to hear the bloody thing and remember to thank me later!
We might add that USA Hifi, distributor for Redgum, Edwards Audio. Coda, Audio Art and Liberty Acoustics to name a few, has been around for a long time and has an outstanding reputation for customer service in the US and Canada. Owner Carl James is the type of guy who enjoys working with audiophiles and giving them solid advice, as well as great prices.
Power Output: 155 + 155 Watt/Ch RMS (293 + 293 W RMS - transient)
Harmonic Distortion: less than .009% (below Clipping)
Intermodulation Distortion: less than .005% (below Clipping)
Signal to noise: greater than 100dB
Input Impedance: 10K ohms (matches 600 ohms - 50K ohms)
Slew Rate: greater than 65Volt / microsecond
Damping Factor: greater than 800
Frequency Response: 0.8 Hz to 80KHz (-3dB points)
Peak Current: greater than 120 amps
Audio Inputs: CD1, AV1, DVD, CD2, AV2
Suggested Speakers: REDGUM RGS Lucens or RGS Regnans (shielded Floorstanding Speakers)
Cabinet Finish: high gloss solid Red Gum wood fascia, gloss black thick steel chassis, heavy duty "Sign Wave" heat sink base
Options: choice of Dual Mono or Single volume;
key switch, rocker or toggle switch;
alternative front panels can made to order (at additional charge) or as supplied by customer;
Other possibilities? Just talk to us about it!
Warranty: Full 7 year Warranty
Dimensions: 420mm (W) x 360mm (D) x 95mm (H)
16.5in (W) x 14.2in (D) x 3.75in (H)
Shipping weight: 11 kg / 24 lb (8.2 kg/18 lb cubic)
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