BC Audio A8 User manual

bcaudio hand-made all-tube non-clone guitar amps
Amplifier No. 8
OWNER’S MANUAL
Models A8, A8HB, A8-240 and A8HB-240
Congratulations on your purchase of BC Audio’s Amplifier No. 8,
developed by award winning amp builder and guitarist Bruce Clement.
That’s me.
I designed Amplifier No. 8 to give the gigging guitar player awesome rock
tones at any volume level. It is a single-channel high-gain amp, meant to
be played loud and driven hard. Construction is heavy-duty, meant for
real-world use and abuse. It will drive any 8 or 16 ohm cab and works
well with pedals. Amplifier No. 8 is made with the highest quality
components, USA iron, and true point-to-point wiring.
I sincerely hope you enjoy playing your new Amplifier No. 8 as much as I
enjoyed building it.

bcaudioAmplifierNo.8Owner’sManual
IMPORTANT SAFETY INSTRUCTIONS
READ, FOLLOW, HEED, AND KEEP ALL INSTRUCTIONS AND WARNINGS.
• DO NOT REMOVE SCREWS ON BOTTOM/REAR. LETHAL VOLTAGES LURK
INSIDE. BOO! CONTACT THE MANUFACTURER FOR SERVICE INFORMATION.
SERVICE MUST BE PERFORMED BY QUALIFIED PERSONNEL.
• THIS AMPLIFIER IS CAPABLE OF PRODUCING HIGH SOUND PRESSURE
LEVELS. CONTINUED EXPOSURE TO HIGH SOUND PRESSURE LEVELS CAN
CAUSE PERMANENT HEARING IMPAIRMENT OR LOSS. WHAT? SPEAK UP!
USER CAUTION IS ADVISED AND EAR PROTECTION IS RECOMMENDED IF
UNIT IS OPERATED AT HIGH VOLUME. WHICH OF COURSE IT SHOULD BE.
• WHEN POWERED ON, THE TUBES MAY BECOME VERY HOT, HOT ENOUGH
TO BURN SKIN ON CONTACT. SO DON’T TOUCH ‘EM. AND KEEP OUT OF
REACH OF CHILDREN AND PETS.
• DO NOT OPERATE WITHOUT SPEAKER OR OTHER SUITABLE LOAD
CONNECTED TO THE SPEAKER JACK, AS DAMAGE MAY RESULT.
• DO NOT OPERATE NEAR ANY HEAT SOURCE.
• DO NOT OPERATE WITH LID IN CLOSED POSITION (MODELS A8 AND A8-240)
OR WITH VENTILATION OPENING(S) COVERED, AS THIS MAY OVERHEAT THE
AMP. DUH.
• DO NOT USE NEAR SPLASHING, FALLING, SPRAYING, OR STANDING
LIQUIDS. AND DON’T EVER LET SOME FOOL SET HIS DRINK ON YOUR RIG.
• CLEAN ONLY WITH A LINT-FREE DRY CLOTH. DO NOT USE CLEANING
AGENTS.
• CONNECT POWER CORD ONLY TO A POLARIZED, SAFETY GROUNDED
OUTLET WIRED TO CURRENT ELECTRICAL CODES AND COMPATIBLE WITH
VOLTAGE, POWER, AND FREQUENCY REQUIREMENTS STATED ON THE
APPLIANCE.
• PROTECT THE POWER CORD FROM DAMAGE DUE TO BEING WALKED ON,
PINCHED OR STRAINED.
• UNPLUG THE APPARATUS DURING LIGHTNING STORMS OR WHEN NOT IS
USE.
• REPLACE FUSE WITH CORRECT TYPE AND RATING AS INDICATED IN THIS
MANUAL AND ON THE APPLIANCE.
• ONLY USE ATTACHMENTS, ACCESSORIES, STANDS, OR BRACKETS
SPECIFIED BY THE MANUFACTURER FOR SAFE OPERATION AND TO AVOID
INJURY.
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OVERVIEW
MAJOR FEATURES
Built by me in the USA
100% All-Tube Signal Path
True Point-to-Point Wiring
Heavy 16ga Powder Coated Steel
Chassis
American-made Paper Bobbin/Paper
Layer Wound Transformers
Stainless Steel Hardware
Tube Rectifier
Class A Cathode Biased Output
Section
Octal Preamp
Combination Power/Standby Switch
Unique Drive Control
Master Volume Control
Presence Control
Will Drive Any 8 or 16 Ohm Guitar
Speaker Cabinet
TUBE COMPLEMENT
(1) 5AR4/GZ34 Rectifier
(2) 5881 Power Tubes
(2) 6SL7 Octal Preamp Tubes
ESSENTIAL INFORMATION
Tube placement, left to right (facing the front, see diagram, p. 4):
V5 V4 V3 V2 V1
GZ34 5881 5881 6SL7 6SL7
Never use a solid state rectifier replacement module in place of a tube rectifier,
unless it is designed to emulate the rectifier you are replacing, in which case,
why not just use the real thing?
Power (Models A8 and A8HB): 120VAC, 60Hz, 1A
Power (Models A8-240 and A8HB-240): 240VAC, 60Hz, 0.5A
Fuse (Models A8 and A8HB): 2A Slow Blow, Type 3AG, 1/4” x 1-1/4”
Fuse (Models A8-240 and A8HB-240): 1A Slow Blow, Type 3AG, 1/4” x 1-1/4”
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bcaudioAmplifierNo.8Owner’sManual
CONNECTIONS AND CONTROLS
Model A8 (A8-240 Similar)
Models A8HB and A8HB-240 – Front Panel
Model A8HB – Rear Panel (A8HB-240 Similar)
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1. Input Jack
Plug a guitar cable into the INPUT jack, and the other end into your guitar, pedal
board or accordion.
2. Drive
DRIVE sets the amount of gain in the preamp section. DRIVE incorporates an
original BC Audio circuit that allows for a very wide range of rich clean to thick
overdriven sounds (see p.6).
3. Volume
VOLUME sets the overall loudness of the amplifier. At high VOLUME settings,
the 5881 power tubes can be overdriven, adding even more rich harmonic
complexity to the sound, while still retaining smoothness and control.
4. Presence Control
PRESENCE adjusts the amp’s overall brilliance and bite. Unlike a “Tone” or
“Treble” control, Presence works in the amp’s power section to subtly change the
sound and feel of the amp. Lower settings produce a darker, “browner” sound
(yeah, I know), while higher settings produce a brighter, sharper tone.
5. Speaker Output Jack
Plug a speaker cable into the SPEAKER jack, and plug the other end into any 8-
or 16-ohm guitar speaker cabinet. Be sure to use a speaker cable, not a guitar
cable, or damage to the cable, the amp and your reputation may occur.
6. Power/Standby Switch
Amplifier No.7 is equipped with a combination Power/Standby switch. To turn on
the amp, move the POWER switch to the center STBY (Standby) position to
allow the tubes to warm up. After a half-minute or so, flip the switch up to the ON
position. To turn the amp off, simply flip the switch all the way down to OFF.
There’s no need to put it in Standby when shutting down.
7. Power Indicator
The Power Indicator lamp will illuminate when power is connected and the
POWER switch (6) is set to either STBY (Standby) or ON. If it doesn’t light, the
power is not connected, or the fuse (8) has blown.
8. Fuse Holder (Top of Chassis on Models A8 and A8-240)
Disconnect power before changing the fuse. Push in and turn counter-clockwise
to remove the fuse. Replace with same type and rating only (see p. 3). On
Models A8 and A8-240, you will need to remove one of the tubes adjacent to the
fuse holder (V4 or V5) to access it.
9. IEC Power Inlet
With the POWER switch (4) in the OFF (down) position, plug the included power
cord into the IEC power inlet, and the other end into a suitable power source.
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bcaudioAmplifierNo.8Owner’sManual
SETUP
Opening and Removing the Lid (Models A8 and A8-240 Only)
To open the lid, lift up on the side latch, then pull the lid open.
If you place the amp on top of a speaker cabinet, I suggest that you detach the
lid and place it out of the way to avoid vibration noise from the handle. To detach
the lid, open it at about 90 degrees, then slide it sideways at the hinge. To put
the lid back on, align the holes with the pins and slide it on. This can be a little
tricky in a dark bar at 2am, so take your time.
Sometimes the small handle attached to the end of the can will vibrate. You can
eliminate vibration by looping your guitar cable through the handle.
Stage Placement (Models A8 and A8-240 Only)
I like to place Amplifier No. 8 on top of a speaker cabinet, but you may place it on
the floor next to your cab or rack, or even up front with your pedal board.
Place it on its side, controls facing forward and tubes vertical; or on its bottom,
controls up and tubes horizontal. The metal enclosure will remain a bit cooler
with the amp placed on its bottom. Heat rises, you know. The case may get
quite hot; this is normal.
Contact BC Audio for a rack mount kit.
PLAYING IT
Control Settings
There are only three knobs, so you won’t have a hard time dialing in your sound.
And like the great amps of yesteryear, you can’t really get a bad tone out of
Amplifier No. 8. Plug it in, set the controls just about anywhere, and off you go.
To really hear Amplifier No. 8 and what it can do for you, I suggest you start out
by plugging your guitar directly into the amp without any pedals, rack gear or
multi-fx units.
Amplifier No. 8 is a high-gain amp. But it also can produce stellar clean and
semi-clean tones. With other high-gain amps, you may have been disappointed
by their thin, weak, anemic clean tones. Sure, the massive, brutal distortion is
great, but you just can’t coax a good clean sound out of it to save your life!
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Not so with Amplifier No. 8. The DRIVE control features an original BC Audio
circuit that solves this problem. At low DRIVE settings, you will find a full, rich
clean sound, not thin or weak at all.
As you bring up DRIVE, subtle tube distortion enhances and enlivens every note
and chord with a velvety three-dimensional chime. This effect is even more
pronounced at high VOLUME settings.
You will find that the transition from clean to overdrive is incredibly smooth. With
just the touch of your fingers you can vary the harmonic complexity of each note.
Clean it up with a light touch, or dig in for blooming organic crunch.
By the time DRIVE is up to 5, you’re into serious heavy, thick tube overdrive.
Push on, my friend, and violin-like sustain awaits your lead explorations.
The octal 6SL7 preamp tubes have a very power-tube-like character, giving
Amplifier No. 8 a big-amp sound, even at low volume.
But wait, there more!
Now, we’ve just run through what happens with various settings of DRIVE. But
there’s more to Amplifier No. 8 - much more.
Like all BC Audio products, Amplifier No. 8 is was developed explicitly for the
gigging musician. It’s at stage volume that the 5881 power tubes add their own
character to the sound.
To hear the power tube magic, start with DRIVE low and VOLUME high.
Depending on the setting of DRIVE and the strength of your pickups, power tube
breakup will occur at VOLUME settings of about 7 and higher.
The GZ34 rectifier also comes into play at stage volume, providing just the right
amount of “sag” to the B+ voltage as the power tubes draw more current. The
resultant natural tube compression gives Amplifier No. 8 a “singing” quality.
Adjust PRESENCE for the desired amount of bite.
Tone Tip: Use your guitar’s volume controls! Set the amp for the most gain you
will need, then back off the guitar’s volume to clean it up. Some of the smoothest
clean tones you will ever hear can be had by backing off on an overdriven tube
amp.
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LIMITED WARRANTY
BC Audio warrants this product against defects in materials and workmanship for ONE (1)
YEAR from date of original retail purchase (30 days for tubes). BC Audio reserves the
right, before having any obligation under this limited warranty, to inspect the damaged
product, and all costs of shipping the product to BC Audio for inspection shall be borne
solely by the purchaser. In order to recover under this limited warranty, Purchaser must
make claim to BC Audio within 30 days of occurrence, and must present acceptable proof
of original ownership (such as original receipt) for the product. BC Audio, at its option, shall
repair or replace the defective unit covered by this warranty.
This limited warranty does not cover any damage to this product that results from improper
installation, accident, abuse, misuse, neglect, natural disaster, insufficient or excessive
electrical supply, abnormal mechanical or environmental conditions, or any unauthorized
disassembly, repair, or modification. This limited warranty also does not apply to any
product on which the original identification information has been altered, obliterated or
removed, has not been handled or packaged correctly, has been sold as second-hand or
has been resold contrary to the US export regulations.
This limited warranty covers only repair or replacement of defective BC Audio products, as
provided above. In the event of a claim, BC Audio's sole obligation shall be replacement of
the product.
DISCLAIMER OF WARRANTY
EXCEPT FOR THE LIMITED WARRANTY PROVIDED HEREIN, TO THE EXTENT
PERMITTED BY LAW, BC AUDIO DISCLAIMS ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING ALL WARRANTIES OF MERCHANTABILITY AND/OR FITNESS
FOR A PARTICULAR PURPOSE. TO THE EXTENT THAT ANY IMPLIED WARRANTIES
MAY NONETHELESS EXIST BY OPERATION OF LAW, ANY SUCH WARRANTIES ARE
LIMITED TO THE DURATION OF THIS WARRANTY. SOME STATES/PROVINCES DO
NOT ALLOW LIMITATIONS ON HOW LONG AN IMPLIED WARRANTY LASTS, SO THE
ABOVE LIMITATIONS MAY NOT APPLY TO YOU.
LIMITATION OF LIABILITY
REPAIR OR REPLACEMENT OF THIS PRODUCT, AS PROVIDED HEREIN, IS YOUR
EXCLUSIVE REMEDY. BC AUDIO SHALL NOT BE LIABLE FOR ANY SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING, BUT NOT LIMITED TO,
PROPERTY DAMAGE, LOST REVENUES, LOST PROFITS, RENTAL OF
REPLACEMENT EQUIPMENT, DOWNTIME, DAMAGE TO PROPERTY, AND THIRD-
PARTY CLAIMS, ARISING OUT OF ANY THEORY OF RECOVERY, INCLUDING
WARRANTY, CONTRACT, STATUTORY OR TORT. NOTWITHSTANDING THE TERM
OF ANY LIMITED WARRANTY OR ANY WARRANTY IMPLIED BY LAW, OR IN THE
EVENT THAT ANY LIMITED WARRANTY FAILS OF ITS ESSENTIAL PURPOSE, IN NO
EVENT WILL BC AUDIO'S ENTIRE LIABILITY EXCEED THE PURCHASE PRICE OF
THIS PRODUCT. SOME STATES/PROVINCES DO NOT ALLOW THE EXCLUSION OR
LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE
LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU. THIS WARRANTY GIVES
YOU SPECIFIC LEGAL RIGHTS AND YOU MAY ALSO HAVE OTHER RIGHTS THAT
VARY FROM STATE TO STATE AND PROVINCE TO PROVINCE.
©2010 Bruce Clement, BC Audio, San Francisco
Other copyrights and trademarks are the property of their respective owners.
www.bcaudio.com