Anthem STR power amplifier

Written by on 03/24/2018 in Latest Auditions, News - No comments

The first new product to grace our newly built music/demonstration room for listening impressions is the beautifully crafted Anthem STR power amplifier. Over the coming weeks we will be adding more detail to this post as we come to terms with this little monster in our midst.

Earlier this year Canadian high-end manufacturer, Anthem, launched a brand new effort into high quality stereo reproduction in the form of their ‘STR’ range which consists of three new units, a preamp, power amplifier and an integrated amplifier. STR refers to the Stereo configuration of the range which for Anthem is perhaps a bit of a departure considering their firm roots in the multi-channel industry. Against the backdrop of their impressive AVM60 surround sound preamp we sampled at the end of last year, we were keen to get our hands on the new STR power amplifier to see how the implementation of good old Class A/B technology serves this effort.

The STR power amp is rated at 400W RMS into 8ohms and this output is specified to increase all the way down into 2ohms with a whopping 800W RMS available here. These days we see a lot of Class D offerings making similar power outputs at eight and four ohms, but there is a substantial difference between what Anthem decided to do in the STR and that of the class D competition. Often class D designs are not stable into low impedances and in real world terms this is more than of some little concern.

Loudspeaker loads are seldom consistent and in-fact can vary wildly as it is fed with a wide range of frequencies and sounds all at the same time. One of my favorite speakers, the B&W 802 Diamond, is such an animal that can unknowingly punish amplifiers very hard.

The Anthem STR amplifier with its true dual mono class A/B design has no issues with difficult loads though. Its sound remains clean and exceptionally controlled even when driven hard with complex music program. This amp really packs a punch and dynamically speaking it never stops giving the impression that there are endless reserves on tap.

My resident Audio Exklusiv Electrostatic loudspeakers offer a different kind of difficult load however. By nature electrostatics are transformer coupled meaning their loads are fairly static, but this also means they do not let up and keep the amplifier’s output stage and power supply relentlessly occupied in a linear type of fashion which can be extremely taxing in its own way.

Dual Mono refers to the fact that inside the amplifier’s chassis the left and right channels are completely independent from beginning to end. In the Anthem we see a substantial Toroidal transformer for each channel and we also see two separate but identical circuit boards mounted on their own individual heat sinks for each channel.

The STR amplifier has been engineered well and it shows in the effortless way it took charge of whatever loudspeakers and music I threw at it. The heatsinks remained pleasantly cool at all operating conditions and as mentioned previously, this amplifier possesses a visceral iron fisted control of the likes that reminded me of the famous big Krell amplifiers of old.

This new Anthem amp is not just about power however. It is pleasantly musical and a joy to listen to for extended periods at a time. Compared to other offerings in this price bracket, the STR impressed me with its rich harmonic overtones on acoustic music and especially human voice. There is also a natural flow to the music, the beauty of which is unmistakable as it reassembles musical events with conviction.

It is also noteworthy to mention how this amplifier looked after dynamics in music that on other amplifiers could come across as if somewhat restricted. The Anthem often recreated the same music with more bounce and greater contrasts between soft and loud. It produced the music with enough drama to keep its audience entertained throughout and this was especially true for my electrostatics, the likes of which can be hard to please.

The Anthem STR is an attractive looking piece of equipment with really impressive build quality for the price. I liked the screen and meter readouts which can be defeated if so pleased. It’s a nice touch of modern cool and in the realm of testing as we so often do, they proved valuable for insight into how the loudspeakers interacted with it on a general basis.

Around the back the layout is good and the connectors of top notch quality. There are balanced and single ended inputs as well as a clever autosensing circuit that brings the amplifier out of standby as soon as signal from the preamp is received. I liked this feature since my resident Conrad Johnson preamp came before the days of triggers.

One note of caution for those with valve preamps like me is to make sure the fairly low input impedance of the STR is compatible with that of the unit intended to drive it. At 10kohms for single ended, the preceding unit will require a minimum of 15uF coupling capacitance to ensure flat frequency response to below 20hz.

List price is R89,900. Call Leander on 0820886688 for more information.

About the Author

Audio Engineer, Critic & Retailer twenty-seven years in the making.

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