A Word About Tubes; System Block Diagram - Crate Professional BV-60H Owner's Manual

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BV-60H/120H

A Word About Tubes:

Vacuum tubes can only last so long. Allowing your amp to cool down before moving it will help prolong the life of
the tubes. Even so, after about a year (or sooner if you're on tour or jammin' more frequently than most) you may
notice the output of your amp just isn't as "alive" as it used to be. If the sound from your amplifier starts to grow weak,
lacks punch, fades up and down, loses highs and lows, gets "funny" (clanking sounds, etc.), it's very likely that the
power tubes are worn out and need replacing. Since power tubes work together in an amplifier, it is important that they
all be replaced at the same time with a matched set of tubes.
If the amp starts to squeal, gets noisy, loses gain or starts to hum, the preamp tubes may be bad. Insist upon
using only the highest quality, low-microphonic tubes!
NOTE: Tube replacement should always be done by a qualified service technician, since adjustment of the
internal biasing controls will be necessary after the new tubes are installed. Also, removal of the tubes may
expose extremely hazardous voltage levels, which could cause injury or death.
To help prolong the life of your tube amplifier, and to keep it in top performing condition, please observe the fol-
lowing guidelines:
• Always match the impedance of your speaker cabinet(s) to the amplifier's impedance selector switch setting.
• In cold weather, allow the amplifier to warm up to room temperature before turning it on (to prevent cracking
the tubes).
• Allow the amplifier a moment to cool down after playing it before you move it.
• Protect the amplifier from exposure to dust and moisture. If liquid gets spilled into the amplifier, or if it gets
dropped or excessively jarred, have it checked out at a service center before using it.

System Block Diagram:

INPUT
TUBE
STAGE
LOW
GAIN
All-Tube Professional Series
TUBE
STAGE
MID HIGH VOLUME
TUBE TUBE TUBE TUBE
STAGE STAGE STAGE STAGE
SEND
REVERB 1
REVERB 2
Guitar Amplifiers
CHANNEL
SWITCHING
LOW MID HIGH MASTER
PAD
SWITCHING
RETURN
EFFECTS
EFFECTS
SWITCHING
LOOP
POWER
IMPEDANCE
AMP
SELECTOR
SPEAKER
PRESENCE
FREQUENCY
COMPENSATOR
OUTS
LINE
OUT
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