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Positive Feedback ISSUE 53
as reviewed by Michael Wechsberg
Anedio is devoted to using cost effective technologies to realize high quality music systems for both audiophiles and everyone else. In the case of the A1 Stereo Power Amplifier the cost effective technology is a pair of National Semiconductor integrated circuit power amplifiers. Now, before all you audiophiles out there turn the page (or click the back button more likely) read on for just a minute, because the Anedio A1 has the sound quality of a truly a high-end amplifier worthy of many an audio system out there, and it only costs $1090 for a 70W (into 8 ohms) stereo amplifier.
Let me get the controversial stuff over with first. Yes, the Anedio uses integrated circuits (IC) instead of discrete transistors or even tubes like everyone else out there. ICs have been used effectively in preamps for some time, but their use in power amplifiers is rare. Through successive design iterations, the IC designers have addressed and conquered many of the problems in early IC power amps. Anedio did some experimenting with the latest generation National Semiconductor LM 3886/LM4780 ICs and discovered that they can be made to sound quite good if the circuitry around them is optimized properly.
There are certain advantages to using ICs that are discussed on the Anedio web site: http://www.anedio.com/index.php/article/why_ic_power_amplifiers .
What it comes down to mostly is small size. In conventional power amplifiers the circuitry is laid out over a square foot or two of area. This makes the circuit subject to induced currents that add distortion, non-uniform thermal effects in different parts of the circuit, and odd transient effects just because of the size of things. Some of the best amplifiers I know are ones that deliberately attempt to minimize the number of components and the length of the signal path (see for example my review of the Silicon Arts ZL-120 amplifiers in Issue 42). You get this for free with an IC power amp. It is small, most of the chip is at the same temperature all the time, and only a few outside components and a power supply are needed to get music out of the thing.
One down side is the power is limited, but this can be overcome to some degree by using bridging amplifier techniques. The other concern is the expertise of the IC designer and his or her ability to produce amplifiers that make music and not mere noise. If you go to the National Semiconductor web site about these ICs you will not see a single word about sound quality other than the devices are very quiet and produce low distortion. They crow about the thermal tracking circuit that prevents the amplifier from burning itself out if it's overdriven.
Another advantage of these IC amplifiers is they are inexpensive. The chips themselves can be had for $7 or $8 (although Anedio may buy specially selected ones that cost more) and a brief web search found a few stereo amplifier kits out there for around $300. I'm sure these amplifiers are used in some home theater equipment out there but I don't know of specific examples.
Anedio does not give much information about what secret sauce they use to juice these amplifiers up to audiophile standards. They mention optimizing the circuitry around the ICs, which I think means they use high quality resistors and capacitors and a smart design, plus taking care with the printed circuit board layout, especially with respect to grounding. Certainly the visible parts are all top notch including gold plated RCA input connectors and top-quality speaker terminals. They have also installed the amplifier in a thick, solid aluminum chassis tightly coupled to a copper heat spreader, with pointed feet on the bottom. Anedio says this makes the circuit impervious to externally-induced interference and acoustic vibration. The chassis also runs very cool even when the amplifier is driven hard. I should mention the amplifier is quite small (9.0 x 3.4 x 13 inches) and only weighs 17 lbs. You might think this is one of those dreaded Class D amplifiers by its size, which it decidedly is not (plain old class AB I think with liberal negative feedback). I'm sure the chassis itself costs more than the $300 kits I saw on the internet. The Anedio A1 definitely looks high end and handsome. The sculpted ends of the amplifier glow a soft blue when the amplifier is on. It puts out 70W continuous into 8 ohms and 75W into 4 ohms. 90W of dynamic power is available for short bursts. The Anedio is dead quiet with a signal-to-noise ratio of 114 dB at full power and harmonic distortion of 0.0007%. The Anedio web site has more specifications for the technically inclined.
One unusual and extremely worthwhile feature of the Anedio is its ability to support passive bi-amplification if two amplifiers are used in the system. I'll talk more about this later as this is the way to get the best out of this beast.
To get at how the Anedio sounds I inserted it into my system in place of my E.A.R. 890 amplifier (coincidentally also a 70W amplifier although it sounds much more powerful). The front end was all tube with the E.A.R. 868 preamp and E.A.R. Acute CD player. Discs were spun on a Townshend Rock 7 turntable with Dynavector 17D3 cartridge. I normally use a balanced cable between the preamp and amp but the Anedio is single ended so I used a Kubal-Sosna Fascination interconnect. This cable alone costs almost as much as the amplifier. Other cables included Harmonic Technology Pro9 Reference SE Bi-Wire speaker cable and a Harmonic Technology Magic Reference power cord.
Let me mention here that the manual states that interconnects and speaker cables using exotic materials are "unnecessary." The most important thing, it says, is to keep the cables short. I found this statement "unnecessary" in the manual and I completely ignored it. I used cables and power cords that each cost more than the amplifier itself and never tried it with plain Jane cables. The results you get with this amp, which is very revealing, may differ depending on the other equipment and cables that you use.
Seventy watts is plenty of power in my medium size room with the average efficiency of my Marten Miles II speakers. Some readers with larger rooms or less efficient speakers might stress the power capability of the amplifier. I suggest you discuss your system parameters with Anedio before buying.
Reviewer Victor Chavira (see his review here) had the amplifiers for a while before I got them and broke them in, so I only warmed the A1 up for 4 – 6 hours before starting to listen. Although I was skeptical of the use of IC amplifiers my initial impression was very favorable. First, this amplifier is dead quiet and, late at night when everything else is quiet, allows very low level details in the music to be heard and enhances the perceived dynamic range. I was also most impressed by the bass response that was low, detailed, fast and tight. Moving up the scale, the mid-bass was quite full, placing a firm foundation under large scale classical orchestra. The midrange as heard on vocals, small jazz pieces and small scale classical was very believable, but I wanted to turn the volume up to hear more detail and transparency. The highs were very nice, clean and revealing with good transparency, but I wondered if it would sound as good with a solid-state front end instead of tube. In any event, the Anedio allowed the character of the source and front-end components to come through clearly. Some of the air and ambience heard with much more expensive components was missing. I was also let down a bit by the sound of horns and woodwinds on some of my favorite classical recordings. They did not have the bite and attention grabbing timbres I'm used to.
Although the Anedio created a wide soundstage, the presentation was relatively flat and forward-sounding. This won't be important with all recordings but it bothered me on some of my best recorded reference music. Overall, I was very surprised by how good the Anedio sounded for a $1090 amplifier. It did not add anything bad to the music and the low-noise, low-distortion technology enabled the amplifier to get out of the way and allowed the character of the music to come through.
However, there was more magic to be had with this amplifier. Anedio supplied two copies of the A1 in order to allow exploration of its passive bi-amplification mode. Many PFO readers I'm sure use bi-wiring wherein two sets of speaker cables are run to the speakers, one to service the low frequencies and a second to service the high frequencies. This reduces some distortion due to interaction between the cables and crossovers inside the speaker. I find bi-wiring my Marten Miles II speakers (which have two sets of speaker terminals) improves the pacing of the music and helps with imaging as well.
In bi-amplification, two separate amplifier channels are used to drive the high and low ends of a single speaker, providing even more isolation between the high and low end drivers. The A1 has a small switch on the back that changes the amplifier from normal to bi-amp mode. In this mode only a single RCA interconnect is attached to each amplifier and the two sets of speaker terminals are used to connect a single speaker. Anedio says its implementation of bi-amplification is special. Here is a discussion from their web site:
Anedio's implementation of passive bi-amplification offers an important benefit: immunity to ground noise when two amplifier channels are tied to a single input.
A pitfall in bi-amplification is the potential ground loop introduced when the two inputs of the stereo channels are tied together. Depending on how the amplifier grounding system is designed, the additional ground noise can be quite high. That is why, in some systems, passive bi-amping actually degrades the sonic quality.
In the A1 Amp, the bi-amplification feature was conceived at the very beginning of the design stage, not as an afterthought and is optimized for the lowest ground noise. Even when the two amplifier channels are configured for bi-amplification, the noise level remains extraordinarily low. Moreover, the bi-amplification mode is activated with a built-in switch, and there is no need for an external Y cable.
I broke out the second amplifier and changed around my speaker cables to try out the bi-amp mode. I kept as many things as possible the same but I did have to introduce a second set of cables for the low end (the Harmonic Technology speaker cables I use have a single set of terminals at the amplifier end and two sets of terminals at the speaker end). I used an XLO Signature 3 speaker cable for the low end and kept the Harmonic Technology for the high end.
Passive bi-amplification made all the difference in how this amplifier(s) sound. The sound stage broadened and deepened and the dynamic contrasts within the music were much improved. I found I was able to follow individual instrument lines much easier and small-scale pieces had a much more "in the room" feel. Larger scale works including orchestra, rock and jazz all became more exciting and believable. That "bite" I was looking for on horns was still not as good as I've heard in my reference system, but was certainly better. Everything had more air and texture as well as pace. I thought the bass was not quite as tight in this mode, but I suspect that is an artifact of using a different speaker cable for the low end.
I also heard more detail in the highs and more clarity in the midrange. Some vocals that were a bit murky in the normal mode cleaned up quite a bit in bi-amp mode. A recording I and other audiophiles use for a quick equipment assessment is "Dialoghi" on Yarlung Records. The first cut is purely piano and cello and is one of the most revealing recordings I've ever heard, but also one that is very difficult to reproduce correctly. In the normal mode the Anedio got a grade of B- on this recording. That's a good score, but in bi-amp mode the score jumped up to A-, a rare accomplishment.
I would venture the use of passive bi-amplification with the Anedio A1 more than doubled the value of the amplifier. The design is very well executed and should banish your doubts about using IC power amps. To use this feature your speakers need two sets of speaker terminals and you have to buy two amplifiers. Anedio sells their wares over the internet and offers a 30 day money back trial. If your speakers are set up for bi-wiring and have the efficiency to sound good with a 70W amp, I suggest you jump on your computer and call up their site. You will have a good time with this one. Michael Wechsberg