. . . .PEARL Tube Coolershave been in continuous production for over 25 years, during which
time more than 300,000 pieces have found their way into audio systems the world over. Perhaps the longest running
and most successful tube audio accessory of all time PEARL coolers have inspired a host of much more costly imitators, none of
which combines the functions of cooling and microphonic reduction achieved by the long-established PEARL design. . . . .Based
on research begun in the early 1950s by the US military and the aeronautical industry, PEARL coolers achieve the
glass temperature reductions shown over 50 years ago to greatly increase the operating life of soft-glass enclosed
electron tubes. Determined during the '50s research is the fact that the "soft glass" almost always used
in receiving tube manufacture is susceptible to high temperature operation in that it becomes effectively "porous"
at elevated temperatures, thereby allowing atmospheric contamination of the high vacuum within the glass. By several
extensively researched and solidly confirmed mechanisms such contamination has been shown to have destructive effects
on the electron emitting surfaces upon which tube functioning is completely dependent and extended tube life relies. . . . .Further,
several tube manufacturers have clearly stated the benefits of envelope temperature reduction. In a Nov. 1959 manual
Brimar Valves stated, "The use of close-fitting screening cans of high thermal conductivity in intimate
thermal contact with a large area of the [soft glass] bulb, in conjunction with an adequate heatsink can materially
reduce the operating bulb temperature and very considerably improve the life of the valve." . . . .Read more . . .
. . . .PEARL CryoValves are another of our industry innovations. . . . .While consulting in 1987
to Museatex, the Calgary-based company that has since grown into EMM Labs we were presented
with an opportunity to chill down a quantity of tubes to -300ºF in Museatex' liquid nitrogen chilled "cold
box" freezer. To say that we were taken by the changes wrought is to make rather an understatement . . . and
after much research and development we have been treating tubes ever since. . . . .Over the years an entire
industry has sprung up following our lead; with two of our previous audio-industry customers having purchased cryogenic
treatment equipment of their own.
. . . .Noteworthy however is the
fact that our cryogenic treatment is an immersion process that is run for fully 100hrs. at a -325ºF soak temperature.
This, as opposed to the 8hr. "soak" in what amount to the "cold boxes" that typically chill
to only -300ºF by liquid nitrogen vapor alone employed by those following our footsteps. Because the extent
of metallurgical change that occurs during cryo-temperature processing is a "time at temperature" product,
longer treatment at lower temperatures will produce more of the changes so beneficial to audio performance. . . . .Subsequent to cryo treatment
we do a 100hr. vacuum enhancement procedure followed by a lengthy triple-anneal process. Following these processes
we do a 100hr. burn-in during which stochastic electrostatic forces are employed to further stress relieve the
tubes' inevitably vibration sensitive and often highly resonant grid structure(s). This done we clean and polish
away the hard, and very bad sounding oxide coating from the thru-glass pins not cleaned by the manufacturer, as
most are not. Finally, we do a comprehensive series of parametric, gain (and gain match in dual triodes), noise
and microphony measurements and provide all the data on the box in which the tube is shipped. . . . .While others claim to provide
the industry's best services, we remain the process innovators and continue to provide a level of service that
is simply unmatched, much less bettered. . . . .Read more . . .
PEARL Iso-sockets uniquely isolate 7- & 9-pin vacuum tubes from structure-borne vibration
. . .