[size=large]Portable Tubes![/size]
The EarMax can now also be used as a portable unit, for tubes-on-the-go. During the course of this
review, the "PakMax" became available. This consists of a 12 V, 4.6 Amp-hour battery from Eagle
Picher, one EarMax Current Converter (ECC) to convert the battery's DC to AC (12 VDC to 19 VAC)
to power the EarMax, and a battery recharger. The battery is about the same size as the EarMax, at
approximately 3.5" W x 2.75" D x 4.0" H, but it appears to be larger because these are solid dimensions,
while those for the FarMax include a lot of empty space around the tubes. The primary disadvantage is
that the battery is heavy, at 4.1 lb., and lasts about 2.5 hours before requiring a recharge. That means
two batteries for a cross-country flight. (But note that other batteries with more Amp-hours are available,
e.g., the 7.7 Amp-hour HE12V7.7, which will last about 5 hours. It is commensurably heavier.) The
Eagle Picher 500C cyclic charger produces 500 mA. Its cyclic nature means that the battery should not
be allowed to undergo deep discharge below 10.5 VDC), if its expected lifetime of 75 to 100 recharges is
to be realized when using this recharger. Listening for approximately 2.5 hours is fine, but beyond that
care should be exercised. The ECC will "chirp" when the voltage is too low. A small voltmeter to check
the battery's charge is a useful accessory. Following recharge, a fully charged battery should read 125-
12.8 VDC.
The Eagle Picher 500F floating charger is also available, for those who do not wish to keep track of the
battery voltage. It is a very gentle, almost a trickle, charger, and will be less harmful to the battery if it
does undergo deep discharge. The EarMax can also be powered from any other suitable 12 VDC source
(including solar panels!). Hart and Beth Huschens are working on a carrying case for all of this
paraphernalia (not the solar panels), which will also
include a compartment for your favorite headphones. Listening tests with the EarMax powered by the
PakMax, rather than by house current, were repeated with my favorite source material. The differences
are a bit subtle, but careful listening revealed battery power to be superior to SoCal Edison power. With
the PakMax, the reproduction was cleaner, had better definition, was more musical, and was even easier
to listen to. I look forward to the development of the carrying case, and my first opportunity to listen to
the EarMax while doing my all-too-frequent bi-coastal LAX-DC shuffle.
Besides the carrying case, also in the works is an accessory to convert the output impedance to 40 ohms,
so that Grado head phones can be optimally used. This adapter will employ miniature transformers
similar to those used by the German army. Dual outputs may be provided for two low-impedance
headphones, with the tag line "shared joy is double joy." The adapter should be available by about
August, 1996, and it will make the EarMax available to a wider spectrum of headphone lovers.
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