Atomic Reactor 50/50 User manual

Atomic Reactor 50/50
2×50W STEREO RACKMOUNT FULL RANGE TUBE POWER AMP
www.atomicamps.com
OWNER’S MANUAL

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Any other product names, trademarks or names are the property of their respecve owners
which are in no way associated with or aliated with Atomic Ampliers LLC
© 2011 Atomic Ampliers LLC. All rights reserved.
Atomic Ampliers LLC • [email protected] • www.atomicamps.com
WARNING!
TO PREVENT FIRE OR SHOCK HAZARD, DO
NOT EXPOSE THIS UNIT TO RAIN OR
MOISTURE.
NO USER SERVICABLE PARTS INSIDE, REFER
SERVICING TO QUALIFIED PERSONNEL ONLY.
SERVICE BY PERSONS OTHER THAN ATOMIC
AUTHORIZED SERVICE TECHNICIANS MAY
VOID WARRANTY.
THIS UNIT MUST BE
EARTH GROUNDED.

ATOMIC AMPS REACTOR 50/50 MANUAL
1
2 The Atomic Reactor 50/50 Stereo Power Amp
3Panel Features & Funcons
5Using the Reactor 50/50
8Rig Diagrams
10 Maintenance
11 Service
10 Troubleshoong
13 Specicaons
18 Warranty

ATOMIC AMPS REACTOR 50/50 MANUAL
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THE ATOMIC REACTOR 50/50 STEREO POWER AMP is a rackmount, 2 ×50W
amplier designed for use with guitar or full range speaker cabinets. The
Reactor 50/50 was inspired by the demand for a stereo version of our
popular MB-50 “mono block” amplier, created with the stage or studio
guitarist in mind. It is also ideal for acousc guitars, vocals, electronic
instruments, and any other applicaon where a high quality stereo
amplier is needed. The 50/50 delivers full-rated power over a full-
frequency response, with high headroom and very low distoron. In other
words, this is an amp without an opinion; it amplies but does not alter the
character of the sound.
Each channel of the 50/50 is a fully independent 50W amplier with
independent level and presence controls, balanced and unbalanced inputs,
an XLR thru, plus two speaker jacks per side with independent selectable
impedance, allowing a range of speaker cabinets to be connected. It comes
with two 12AX7s and a stereo set of “JJ” 6L6 power tubes. The Reactor
50/50 is also capable of using EL34 tubes. Convenient frontpanel per-
channel bias controls make it possible to perform ne adjustments on-the-
y and even allow the unit’s channels to operate with two dierent sets of
tubes.
The Reactor 50/50 is ideal for the modern digital guitar rig. Together
with Atomic Reactor FR Passive Cabs or Wedges (or the tradional guitar
cab(s) of your choice) it ensures that your preamp, modeler or simulator
will sound great, with plenty of power, presence, and punch. It is built to
last, with a heavy duty steel chassis and ¼” brushed aluminum faceplate.
Even as guitar tone processing technology advances, the Reactor 50/50 will
remain a valuable investment in great tone.

ATOMIC AMPS REACTOR 50/50 MANUAL
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Figure 1: Controls & Connecons of the REACTOR 50/50 Front Panel
Power Switch – Switches both channels of the amplier ON or OFF. The
power light will glow when power is ON.
Unbalanced (¼") Input (×2) – Unbalanced input of the amplier (one per
channel). The ¼” input overrides the balanced XLR input if both are
connected.
Standby Switches (×2) – These control high voltages to the tubes,
independently for each channel. Allow 60 seconds aer powering up before
seng standby to the ON posion.
Warning! If you are only using one channel make sure that the other
channel is set to STANDBY, regardless of whether or not input signal is
present in the unused channel.
Level Control (×2) – These knobs set the output volume for each of the
amplier’s 2 channels.
Presence Control (×2) The acve presence circuit alters the high
frequency component of a signal, adding “brightness” or “sparkle” while
retaining a pleasant high-end quality. The presence circuit is completely
disengaged for true at response with the knob fully counterclockwise.
Channel Fuse – These dual compartments house the 250A Fast blow
type fuses which protect the le and right channels.
Bias Controls – Each channel is equipped with a front panel bias adjust
trim pot, plus its own test point. A common ground serves both channels.
For more on how to adjust the bias of the Reactor 50/50, see p. 7.

ATOMIC AMPS REACTOR 50/50 MANUAL
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Figure 2: Controls & Connecons of the REACTOR 50/50 Rear Panel
Power Input - Connect the supplied AC line cord here. The power inlet
also houses the Fuse Compartment which must be opened to replace the
fuse. In order to convert the power amp from 115v (US) to 230v (EU)
operaon (or vice versa) change the fuse to the appropriate value (see
specs on pp. 13–17), then rotate and replace the fuse compartment.
Cooling Fan (×2) – These quiet fans spin while the amp is on.
Balanced (XLR) Input (×2)– This female XLR-type connector accepts a
balanced or unbalanced line level signal.
Unbalanced (¼") Input (×2) – Unbalanced input of the amplier. The ¼”
input overrides the balanced XLR input if both are connected.
Balanced ( XLR) Thru (×2) – Signals appearing at the Balanced (XLR) Ins
will be output at the Balanced (XLR) THRUs for connecons to a recorder,
mixer, or other device. The ¼" inputs do NOT connect to the THRUs!
Ground Li Switch (×2) – May be used to eliminate the hum or buzz
from a ground loop in either channel of the Reactor 50/50.
Dual Speaker Outputs – Each channel of the Reactor 50/50 has two
speaker output jacks.
Output Impedance Selector Switch (×2) – 4/8/16Ω selectable per side,
sets the impedance in Ohms for each of a channel’s dual speaker jacks.
WARNING! The total impedance of the speaker load connected to a jack
must match that jack’s switch seng, or damage may result!
Tip: Two 8-ohm speakers in series present a 16-ohm load, Ωt = Ωa + Ωb
while two 8-ohm speakers in parallel present a 4-ohm load. Ωt=(Ωa×Ωb) /(Ωa+Ωb)
It is safe to use a channel with speaker(s) connected to only one jack.

ATOMIC AMPS REACTOR 50/50 MANUAL
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The Reactor 50/50 is easy to use and oers the controls needed for a great
range of music performance situaons. NOTE: Always lower the output
level knobs on any connected devices before beginning to operate the
power amp.
1. Connect one or more speakers to the Speaker Output Jacks and
set the Impedance Selector Switch to match their rang(s).
2. Using a high-quality cable, connect a signal source to either the
Unbalanced (¼”) Input or the Balanced (XLR) Input.
3. Connect the supplied Power Cable to your unit’s Power Input
located on the back panel.
4. Turn the Power Switch to ON. The power light should come on.
5. Wait at least 60 seconds for the amplier to warm up, then set the
Standby Switches to ON for ONE or BOTH channels.
IMPORTANT! Never take a Reactor 50/50 channel out of standby
when input signal is present and no speaker or load connected to
the speaker output. Doing so will damage the amplier.
6. Increase the level of your instrument or processor and set the
Master Level of the Reactor 50/50 to the desired level. Adjust the
tweeter level to taste.
WHO’S DRIVING? Whether you like to run your source signal “Hot” and
lower the master volume of the Reactor, or turn up the Reactor and lower
the output level of a connected instrument or processor, you will nd that
the Reactor operates quietly and sounds great.

ATOMIC AMPS REACTOR 50/50 MANUAL
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ATOMIC AMPS REACTOR 50/50 MANUAL
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Your Atomic Reactor 50/50 is vacuum tube driven, and therefore requires
maintenance. Power tubes have a life expectancy of approximately 1000
hours. Regular play requires regular service.
Tube Replacement: The 50/50 ulizes 2 × 12AX7 tubes and four high
quality JJ brand 6L6GC tubes, selected because they oer excellent sound
quality. You will noce degradaon when tubes need to be replaced. The
power secon is built to work with any properly biased 6L6 or EL34 tube.
When tubes need to be replaced, use a qualied amplier technician.
Output Tube Bias Adjustment: A technician will bias your amp when new
tubes are installed. However, you may nd bias dris over me. You can
check and adjust this yourself. Each channel of the Reactor 50/50 is
equipped with a front panel bias test point and adjustment point. A
common ground serves both channels. The bias trim sets the idle current in
the output tubes, properly matching the amp’s performance characteriscs
to the type of tubes used. Each tube type and brand may require a slightly
dierent bias, and sengs should be checked when tubes are replaced. A
properly biased amp will sound great and will run reliably and safely. An
amp’s bias can dri with extended use. To bias the Reactor 50/50, turn
main power ON and take the desired channel out of STANDBY. Touch the
negave lead (black) of a VU Meter to the common ground on the front
panel of the Reactor 50/50. Touch the posive lead to the test point for the
channel you plan to adjust. Adjust the trim with a small athead
screwdriver unl the meter reads in the range of 70–90ma. Once the rst
channel has been properly biased, put it in standby and repeat the bias
adjustment process for the second channel.
Front panel bias controls of the Reactor 50/50.

ATOMIC AMPS REACTOR 50/50 MANUAL
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WARNING! The internal voltages of tube type ampliers are
potenally lethal and capacitors are capable of storing these
lethal charges. The Reactor 50/50 allows you to bias the amps without
removing the panel to expose componentry but you should sll exercise
cauon or refer to the services of a qualied professional.
The Fuse: The fuse protects the amplier in the event of an electrical fault
or tube failure. If a fuse blows, replace it only with one of the required type
and rang. The main fuse is in a compartment built into the AC inlet of the
amplier and can be accessed by opening the fuse compartment with a
small at-head screwdriver or similar tool. In order to change the voltage
specicaon from 115v (US) to 230v (EU), or vice versa, the fuse module
must be rotated 180° and the fuse changed to the correct specied value as
marked above the AC inlet. The secondary per channel fuses are accessible
through the front panel.
WARNING! Always disconnect the amplier’s power cord from
the AC outlet before aempng to change the fuse. Refer to the
specicaon pages (pp. 13-17) to determine the correct fuse type and
rang. NEVER use a fuse with a higher rang as this could damage the amp
and present a serious safety hazard. If the fuse blows repeatedly, the amp
should be taken to an authorized service center.