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Description
The Aaron No.1.a is an integrated stereo amplifier. Its enclosure is rather simple but particularly well crafted and sports a nice visual design on the front panel. There we merely find two conical knobs that double as push buttons and a blue display between them. The right-handed control is for volume and stand-by, the left changes inputs or enters program mode. The latter can set sensitivity for each input and channel, hence balance control is possible, and we can also set an input for unity gain to create a power amp for home cinema systems. The display is quite legible and shows input, volume level and sensitivity .On the back we find plenty of sockets for seven line inputs including a tape loop and an external processor loop for perhaps a room correction device. There is also a preamp output to biamp with or feed a subwoofer. On the top cover sits a thick aluminum plate vibration damper with the company logo engraved. The loudspeaker terminals are single wire and not very good. For a surcharge, Aaron offers a bundle of improvements including better connectors, different finishes for the plaque (you can even have your name put on it) and chassis colors. The loaner finish is called Night Shadow. The amplifier is accompanied by a very solid metal remote which controls volume, inputs and stand-by. The only thing missing is a mono switch.

The inside looks very interesting. A significant part is taken up by a very big toroidal transformer and the power supply. The transformer is packed in a big plastic bin and covered with something compliant, perhaps mechanical or electromagnetic damping as Shunyata employs in its power conditioners. The power supply circuit occupies the same PCB as the preamplifier. There are three separate feeds, two for voltage stabilization and one for the output stage, the latter with six capacitors of 10.000 µF each. The gold-plated but medium quality RCA inputs are switched by relays managed by an encoder coupled to the front panel knob, a very nice looking mechanism with a solid shaft that should guarantee trouble-free operation for years. The actual preamplifier circuits reside on two small PCBs (one for each channel) plugged into the mother board via small pins. The active elements are two Analog Devices OP27 chips per channel and an integrated analog resistor ladder DS1808 that is a digitally operated 60dB-range logarithmic potentiometer with a mute function. This control is divided into three sectors whose step sizes differ. The first 12 taps run in 1dB steps followed by 12 taps at 2dB and 8 taps at 3 dB. Short shielded flying leads from the little PCBs lead the signal to the output boards. Those are mounted vertically because the power transistors are placed somewhat differently than the usual direct coupling to the heat sinks.

Here the heat sink is placed traditionally, i.e. parallel to the side panels but the transistors (bi-polar BD244C + BD243C drivers plus outputs) are mounted to an aluminum channel which then couples to a common heat sink for both channels. The current buffer works in class AB push-pull and is based on a single complimentary pair of transistors per channel. The chosen transistors use TO-3 enclosures I haven't see in a long time, with all the markings removed. The micro processor control circuits occupy a separate PCB near the front panel.

Everything looks well implemented and thought out. Only the quality of RCA sockets and speaker terminals should be better. I think it worth ordering up the hot-rodded version. One final detail: the flying leads to the output stage are bundled with the solid core loudspeaker post leads and the pre-power connections. I know many companies like that who claim that the signal levels are high enough to have no influence on the sound but a practical part in me would like to see those as far apart as possible. But that's just me.

The company provides only minimum technical specification, with output power given as 2 x 95W/8Ω, 2 x 160W/4 Ω, 2 x 250W/2 Ω. I queried Mr. Thomas Höhne on that and he declared it on purpose so as to not distract from the sound with abstract figures.
Aaron website