Infinity Alpha 10 - Modification

Key Features

Speakers Function Main / Stereo Construction 2-Way Connectivity Cable Nominal Power 10 Watt RMS Magnetic Shielding Magnetically Shielded Peak Power Handling 80 Watt

Technical Features

Impedance 8 ohm Sensitivity 88 dB Frequency Response 60 Hz - 22 kHz

Components

Woofer Material Ceramic Metal Matrix Diaphragms (CMMD) Tweeter Size 1" Woofer Size 5.25"

Dimensions

Weight 13.60 lb. Depth 10.25 in. Height 12.63 in. Width 7.13 in.

The Alpha 10's are good looking and good sounding bookshelf speakers. They have bright, detailed and fast response, thanks to the CMMD mid-woofers. With modest listening levels the sound is sturdy and precise, but going into a heavier load and sonic attack, the speaker cabinets start to resonate. This negatively influences the overall performance by adding coloration, distortion and abnormal frequency reproduction. The original design comes with no bracing and no dampening material except the rear panel where a quarter inch thick rubber-foam was used.

Remedy: internal bracing + synthetic dampening material. The result is easily noticeable by knocking on the side walls and listening to the percussiveness. This acoustical treatment improves also clarity and resolution. Moving a step further, the original cable was substituted by AWG 12 Esprit Silver cable, from German manufacturer Sommer Cable. The cable is very flexible and easy to work with. The greatest advantage of Esprit cable is its ultra low resistance and high load acceptance.

The next stage was focused on the crossover and binding posts. The original crossover contained two bipolar capacitors per channel. The disadvantage of using an electrolytic bipolar capacitor is its aging process, where it tends to lose capacitance and other nonlinear characteristics, which downgrades the performance of the crossover.

Remedy: using a capacitor with dielectric such as polypropylene, which is a much better performer under fluctuating voltage, frequency and temperature. Also capacitance tolerances are lower in polypropylene dielectric. The Jantzen Crosscap made from ZnAl polypropylene foil seemed to be a good choice. According to the Jantzen company, this series possesses the best price/performance ratio.

The last part of this modification stage involved the replacement of binding posts. Original terminals were made from simple plastic cups with a single pair of connectors for each speaker. I decided to upgrade the connection system to Bi-Wiring - using either two stereo amplifiers (one per channel) or four mono power amps (two per channel). In this configuration, the amps are less loaded/stressed, since none of them covers the whole frequency range.

ophichus@gmail.com