Onix A-120MKII Integrated Amplifier Review

The thicker solid copper RCA connectors for the CD input add a nice touch of nostalgic value for audiophiles concerned with such matters. I like them because they were firmly coupled to the chassis - easing my concern when attaching and removing even the most exotic and not-so-form-fitting interconnects without fear of breaking them off.

Though I am not a Vinyl fan, lovers of this format should be aware that the Onix A-120 M KII does not contain a moving coil phono preamp. Thus, you will have to add your own and attach it to one of the unused inputs. I don't see this as an issue since true phono fans can always be found chatting up their favorite outboard preamp.

The front panel was void of the gadgetry commonly found on home theater equipment and instead contained a very basic user interface. Consisting of three large golden circular knobs, these sparse controls handled volume, balance (no tone controls) and input. A blue LED indicated power was on and two red LED's indicated a fault (which never tripped even during my max power measurement tests).

Initial power up revealed a momentary 'thump' sound from my speakers, indicating the lack of a muting relay to mute the sound during power supply charging. I was mildly disappointed in this, but given the design philosophy of simplicity and not adding excessive circuitry in the signal path, I could perhaps see the reasoning for this. I, of course, would have preferred a fix for this, but didn't see it as a major issue or potential problem as much as an observation and annoyance.

It doesn't get any more basic than this. This is simply the most primitive and useless remote control I have ever come across. However, considering I am the ultimate couch potato that wants all of my equipment to operate via brainwaves rather than exercising my appendages, I may be a bit overly critical on this point.

Let's also not forget as far as two-channel high end audio is concerned, most of the products from this genre aren't furnished with a remote. However I would have been tickled pink if they at least included a power button and input selector.

Perhaps on the MKIII?

Peering inside the A-120 M KII reveals some impressive and uncommon electronics for a product in this price class. The power supply consists of dual 315VA toroidal power transformers with four (4) 10,000uF 63V power supply capacitors (a more robust power supply than most mid level 7.1 channel receivers).

Editorial Note on the Onix A-120MKII Amplifier Design

• Paralleling multiple BJTs in push pull configuration is a good method of ensuring amplifier output impedance is low enough to deliver high current while driving low impedance loads. It's also an effective way of minimizing frequency response variations which can occur when driving highly reactive speaker loads and exotic cabling.
• Multiple high voltage (63V) capacitors (4 x 10,000uF = 40,000uF total). In order to do 120wpc a minimum recommended cap voltage of sqrt(2)*31 + 5 = 49V should be used. Using 63V gives them plenty of design margin and added headroom since the rails can swing much higher.
• Dual toroidal transformers ensure this amp has the power to back its ability for driving low impedance loads.

I would characterize the sonic signature of this amp to be bold, dynamic, lively and on the warm side. Bass was tight and authorative, as evident in music from Steely Dan 's Two Against Nature and Fourplay's Chant. The more I cranked the volume control, the more my adrenaline rushed, and the happier my speakers seemed to behave - now being driven by quality amplification. Once I developed a good understanding of how the A-120 M KII could drive reasonably efficient small speakers, I was curious to see how it would handle my 4 ohm, less efficient, floorstanding RBH Sound 1266-LSE towers. I usually frown upon driving these speakers with less than 150wpc given their 87dB sensitivity and 4 ohm impedance, but since the A-120 M KII seemed to be built of sterner stuff, I figured I would give it a try. I was pleasantly surprised to hear the Onix amp drive these speakers without incident. This was a good indication to me that the robust power supply and multiple output devices to source high current and maintain a low output impedance was paying off. Not since my experience with the $700 Rotel RA-1062 integrated amplifier have I heard an inexpensive amp deliver the kind of uninhibited raw power with such poise and conviction. The Onix however, did so with more impact and slam in the bass and with a perceived lower noise floor. Granted, the Onix was rated at higher power than the Rotel, but it seemed more than just that fact and I would wait until I benched this amp for a plausible reason.

I continued my listening session on my Decimo's with an intimately familiar flamingo CD that was given to me by my lovely wife on our anniversary a few years ago. This is the type of CD that is most enjoyable at soft listening levels in the quiet silence and darkness of the evening. I use this disc to judge just how well a speaker system, or component gear for that matter, can reproduce the subtle nuances of Eric Hanson's guitars, as well as all of the percussions and too many other instruments to notate here. The A-120MKII didn't disappoint. This CD sounded about as good as I can recall and the warm attribute of this amp was actually a welcomed characteristic in my bedroom system that has limited room treatments.

Next up was an SACD from Gloria Estefan titled Alma Caribena . I chose this disc for a variety of reasons (great sound, great music, great WOW factor). Gloria's voice in "Por Un Beso" sounded wonderfully powerful and crisp. The drums were vibrant and the bass was well extended. "No Me Dejes De Querer " is the type of song you play loud at Columbian parties, or when you have a few moments to yourself with nobody around to yell at you. I had the luxury of the latter and took full advantage of it within the limits of my hearing. The Onix amp again delivered the goods. The bass remained clean and well extended. The overall tonal balance maintained uniformity with no signs of distress within the confines of my listening tests, room dynamics and test gear. Overall, my listening experience was not tainted at high listening levels like I have experienced with inexpensive mass market A/V receivers. I certainly felt as if I was listening to a high end rig unbefitting of the price tag this amplifier would suggest.

The Audio Precision revealed one reason I was hearing authorative bass impact and a warm sonic signature. There was a +2dB bass boost built into this amplifier out to about 200Hz or so. This was obviously a deliberate design attribute which can also be inferred by their published frequency response specification from 20Hz to 20kHz +-1dB. I can't really fault them since it was in fact intended and I did find it pleasing to the ear despite it not being the normal ruler flat response typically found on most consumer gear.

Distortion at 1 watt was respectable (+8.332+68.583)dBv = 76.915dBv or 100*alog(-76.915/20) = .014%.

At full unclipped power, the Onix A-120 M KII delivered about 116wpc into 8-ohms but with the caveat of it being a function of bandwidth. From 20hz to 200Hz it delivered about 30Vrms (116wpc) via 8-ohms for .1% distortion and 26Vrms (85wpc) at 1kHz when fed the same input signal level but at a much lower distortion level. Into 4-ohms the Onix A-120 M KII delivered about 170wpc at .1% THD from 20Hz to 200Hz and roughly 115wpc for the rest of the audible spectrum. Since Onix doesn't specify distortion over a specific bandwidth for their power specifications, we can't declare they didn't meet them. We didn't run into any situations where we felt the amp was short of power during our listening tests.

Distortion at full power was good, though higher order harmonics were more pronounced; (+28.328+49.048)dBv = 77.376dBv or 100*alog(-76.915/20) = .014%.

Signal to Noise Ratio at full power was -103.57 dB below 29.70 dBV Reference Level (at 0.09 % THD+N) <10 Hz - 22k Hz bandwidth, no option filter. With 200mV in, 1 watt out the SNR was found to be 80.4dBrA which is decent performance of a product in this price class.

I won't try to lead you into believing the A-120MKII is without limitations or that you can throw your bulking monoblocks away in favor of this little nugget. However, based on the Onix A-120MKII's effortless drive capability, bass impact, well extended soundstage and low noise floor, I would recommend its no frills build and sonic signature to anyone looking to assemble an affordable, space saving, quality two-channel system. It is especially well-positioned for small to medium sized rooms with moderately sensitive speaker systems having rated nominal impedances of even 4-ohms. If your tastes lean towards a warm "audiophile" sonic signature and you prefer simplicity of operation over the latest and greatest features, this amp is definitely worthy of consideration.