Vox Cooltron - Manual

Owner’s Manual

Many thanks for adding the VOX COOLTRON Bulldog Distortion /Big Ben
Overdrive / Brit Booster

pedal to your rig. Our main goal is to provide you with

the most toneful products anywhere and we believe you’ll enjoy using these
pedals as much as we enjoyed designing them!

What is COOLTRON?

COOLTRON

is the name that we have given to a new way of using preamp type

tubes at low voltage. In our case we chose a 12AU7.

Tubes are normally used at high voltages, and this is the recognised way of using
them, but it negates their use in battery-powered devices such as guitar effects
pedals which is what COOLTRON is!

Historically, attempts have been made to use tubes at low voltages, usually termed
as being used in “starvation” mode. Unfortunately, these circuits have severe
problems in the tube functioning in an acceptable manner. One problem is being
able to bias the tube to a satisfactory operating condition. Another problem is
that the necessary heater (filament) current is too high to provide adequate bat-
tery life which we all know would be annoying when you have to change batter-
ies every ten minutes during a gig.

The COOLTRON system gets over both these problems and provides true tube
sonic performance at a very low voltage and at a reduced heater current – ideal
for inclusion into the aforementioned guitar effects pedals – and therefore can
give these pedals a vast improvement by giving valuable tube sonic performance.

Basic Operation

The COOLTRON circuit basically operates by using two very special circuits:

A) To achieve the required biasing function, a unique circuit is used that

provides the right conditions between the anode (plate) of the tube, and
the grid. In general terms this circuit is called a “servo” circuit, and
replaces the normal self-biasing networks that would normally be used.
Although not the same circuit, this servo theory is used many times in
high-end tube hi-fi, to achieve controlled stable parameters.

B) The heaters are provided with a special power supply that provides a

low voltage and low current supply to the heater elements in the tube.
Due to the servo-biased tube circuit providing the correct operating
conditions for the tube, the tube now functions as it would if run at a
higher voltage – i.e. the signal excursions can be operated linearly, pro-
viding balanced clipping conditions, and with the right harmonic &
distortion characteristics – even when running from a B+ of only 6 volts.
Both of these conditions are virtually impossible to achieve using nor-
mal “starvation” methods.
Due to the tube now running at such a reduced supply level, the anode
current is much, much smaller than normal. This means that the amount
of heat required at the cathode to achieve sufficient cathode current
emission is much smaller – hence the ability to run the heaters at a lower
level.

Therefore both these points combined means that we have a usable tube circuit
running off a battery power supply – battery life is approximately 16 hours from
4 x AA size batteries – but also the tube runs a lot cooler – hence the name
“COOLTRON”

!

© 2004 VOX AMPLICATION LTD.

Printed in Japan

Mode d'emploi de l'utilisateur

Merci d’ajouter la pédale COOLTRON VOX Bulldog Distortion/Big Ben Over-
drive/Brit Booster

à votre arsenal sonore. Notre objectif principal est de vous

fournir les produits aux sonorités les meilleures, où que vous vous trouviez, et
nous sommes certains que vous utiliserez ces pédales avec autant de plaisir que
nous avons eu à les concevoir.

Bedienungsanleitung

Herzlichen Glückwunsch zum Hinzufügen des VOX COOLTRON Bulldog Dis-
tortion/Big Ben Overdrive/Brit Booster

Pedal zu Ihrer Anlage. Unser größtes

Ziel ist es,Ihnen über die klangreichsten Produkte zu bieten, und wir glauben,
dass Sie mit diesen Pedalen so viel Spaß haben werden wie wir bei deren Entwurf!

Manual del usuario

Gracias por la compra del pedal Vox COOLTRON Bulldog Distortion / Big Ben
Overdrive / Brit Booster

. Nuestra intención es ofrecerte los productos con el mejor

sonido y creemos que los disfrutarás tanto como hemos disfrutado nosotros
diseñándolos.

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