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Hugh R. Dean (Aspen Amplifiers)(April 2002): The kits are produced with comprehensive instructions, complete with detailed digital photographs, running to 12000 words and 22 photographs and diagrams for the 55W AKSA, and more for the 100W AKSA. While there are no glossy brochures, there is considerable information and direction on the website.
The assembly instructions include a three page diagnostic section for fault-finding during assembly. This is extremely comprehensive, and covers almost all the problems constructors might confront during setup.
Both AKSA have 3dB points at 25Hz and 42KHz. Distortion at 25W into 8R at 1KHz is 0.032%, which is 70dB down, and primarily second harmonic. Source impedance of the 55W AKSA is 100 milliohms, and 55 milliohms for the 100W version, both into 8R resistive and 1KHz at 25W.
Full schematics and pcb overlays are available with the kitset instructions, but are not offered in the public domain as the circuit design is proprietary and copyright.
AKSA website (April 2002): The AKSA is a family of highly refined push-pull solid-state stereo amplifiers of 100W and 55W per channel. The basic design simplicity belies a stunning audiophile performance totally at odds with humble kitset origins. The motto of Aspen Amplifiers P/L and its designer, Hugh R. Dean, is boutique, unique, DIY.
The AKSA family of audio amplifiers was developed to overcome most of the sonic problems of SS push pull technology, and incorporate some highly innovative thinking, not just dictated by the engineering (which is crucial) but heavily influenced by the subjective issues of listening to music. Mindful of the engineering issues, the design cycle has also been focused on the audiophile listening experience, and the inspired desire to transfer human emotion via the artform of music. The justification for this is simple; people listen to music to be moved, not to marvel at the elegance of the amplifier design.
While engineering has been crucial in achieving the goal of the AKSA, the primary focus has remained the transference of emotion, and to a large degree conventional measurements have been downplayed. In no way does this indicate that distortion measurements and slew rates are not important, but rather that there is more to this technology than first appears. The AKSA amplifiers create a presentation comparable to a quality tube amplifier, whilst delivering stunning resolution and a pure, sweet, musical sound. This has been achieved at very low cost in an attempt to balance the pricing policies of high end audio. Like many tube amplifiers, the AKSA is best suited to quality speaker systems of 88dB/Watt/metre or higher, but the 100W amplifier shines with just about any loudspeaker system, regardless of efficiency..
The amplifier is simple to build. Both channels of the 100W and 55W amps are assembled on their own individual 5" x 2.75" (127mm x 67mm) and 3.4" x 2.95" (86mm x 75mm) printed circuit boards respectively. The 100W amp utilizes one single, ledged 300mm x 75mm heatsink per channel; the 55W amp uses just one of these for both channels. The 100W AKSA is powered from a 49V volt positive and negative supply which is built in dual mono configuration, while the 55W amplifier uses dual mono 36V rails. Both AKSA amplifiers run very efficiently in Class AB with a quiescent current of 55mA per complementary pair, and deliver imaging, slam and clarity rivalling the best Class A designs but with none of the attendant thermal problems.
Key features of both AKSA amplifiers are the utter absence of intermodulation, startling transients, crystalline clarity, and palpable depth of image. This last feature is unusual for solid-state amplifiers. To achieve optimum performance, a dual-mono power supply is specified for both amplifiers (a custom designed printed circuit board is available as a $AUD12 or $AUD9 option for the 100W and 55W amps respectively) - a full schematic for the power supply is included with all kitsets, along with a description of total package assembly.
The complete unit including the power supply can be built in a single day and fitted into a suitable case (not supplied). The impressive heatsink, clearly visible in the photo, is supplied pre-drilled with the kit.
Both AKSA amplifiers have been auditioned against several high end solid-state and tube amplifiers and have been judged 'gob smacking' by some highly seasoned listeners, folk who have listened to some of the world's best. The kitset includes everything required to build up a stereo amplifier, including solder and heatsink paste, and is strongly recommended for DIY enthusiasts who seek audio nirvana but are discouraged by the high entry cost of quality tube amplifiers.
Hugh R. Dean (Aspen Amplifiers)(April 2002): Aspen Amplifiers was established in Melbourne, Australia, in 1994. After an extended period of research, the company began shipping DIY AKSA kits in 2000. The principals of the company are Hugh R. Dean and his wife Sri, and together with part time employees they service all inquiries, administration, email help and kit assembly tasks.
The AKSA DIY kitset is steadily penetrating the European and North American DIY markets. The website, at printedelectronics.com, will change to aspenamps.com in May 2002, and together with the Printed Electronics forum atÂ http://www.harmonicdiscord.com are the sole means of advertising. The 55W amplifier is the result of many years of R&D, and one of a number of related products, including a 100W variant, a unity gain tube line preamplifier, and the AKSonic kitset loudspeaker, a two way bass reflex design which is adaptable to any room.
A 12,000 word FAQ is offered on the website which answers most of the commonly asked questions concerning the AKSA amplifiers.