550x
OWNER’S MANUALSWR• SCOTTSDALE, AZ• USA

IMPORTANT SAFETY INSTRUCTIONSCAUTION: TO REDUCE RISK OF ELECTRIC SHOCK, DO NOT REMOVE THE COVER OR BACK.
NO USER-SERVICEABLE PARTS INSIDE. PLEASE REFER TO A QUALIFIED SERVICE TECHNICIAN.
A. READ INSTRUCTIONS: All safety and operation instructions should be read before the product is operated.
B. RETAIN INSTRUCTIONS: The safety and operating instructions should be retained for future reference.
C. HEED WARNINGS: All of the warnings on this product and in the operating instructions should be adhered to.
D. FOLLOW INSTRUCTIONS: All operating and use instructions should be followed.
E. CLEANING: Unplug this product from the wall outlet before cleaning. Do not use liquid cleaners or aerosol cleaners. Use a slightly
damp cloth for cleaning.
F. WATER AND MOISTURE: Do not use this product near water; for example, near a swimming pool, wet basement, and the like.
G. ACCESSORIES: Do not place this product on an unstable cart, stand, tripod, bracket or table. The product may fall, causing
serious injury to a child or adult, and serious damage to the product.
H. VENTILATION: Slots and openings in the unit are provided for ventilation and to ensure reliable operation of the product, to protect
it from overheating, thus these openings must not be blocked or covered. This product should not be placed in a built-in installationsuch as a bookcase or rack unless proper ventilation is provided or the manufacturer's instructions have been adhered to.
I. GROUNDING: This product is equipped with a three-wire grounding-type plug, a plug having a third (grounding) pin. This plug will
only fit into a grounding-type power outlet. This is a safety feature. If you are unable to insert the plug into the outlet, contact yourelectrician to replace your obsolete outlet. Do not defeat the safety purpose of the grounding-type plug.
J. POWER CORD PROTECTION: Power supply cords should be routed so that they are not likely to be walked on or pinched by items
placed upon them, paying particular attention to cords at plugs and the point where they exit the product.
K. LIGHTNING: For added protection of this product during a lightning storm or when it is left unattended and unused for long
periods of time, unplug it from the wall outlet. This will prevent damage to the product due to lightning and power-line surges.
L. OVERLOADING: Do not overload wall outlets or extension cords as this can result in a risk of fire or electric shock.
M. OBJECT AND LIQUID ENTRY: Never push objects of any kind into this product through the openings as they may touch dangerous
voltage points or short out parts that could result in a fire or electric shock. Never spill liquid of any kind on the product.
N. SERVICING: Do not attempt to service this product yourself as opening or removing covers may expose you to dangerous
voltage or other hazards. Refer all servicing to qualified service personnel.
O. DAMAGE REQUIRING SERVICE: Unplug this product from the wall outlet and refer servicing to qualified service personnel under
the following conditions:
1) When the power supply cord has been damaged2) If liquid has been spilled or objects have fallen into the product3) If the product has been exposed to rain, water, or other conductive liquids4) If the product does not operate normally by following the operating instructions
5) If the product has been dropped or damaged in any way6) When the product exhibits a distinct change in performance.
P. REPLACEMENT PARTS: When replacement parts are required, be sure the service technician has used replacement parts specified
by the manufacturer or have the same characteristics as the original part. Unauthorized substitutions may result in fire,electric shock, or other hazards.
Q. SAFETY CHECK: Upon completion of any service or repairs to this product, ask the service technician to perform safety checks todetermine that the product is in proper operating condition.
R. HEAT: The product should be situated away from heat sources such as radiators, heat registers, stoves or other products that
produce heat.

INTRODUCTION
Congratulations on your purchase of the SWR 550x Bass Amplifier! You now own the latest addition to
SWR's world-renowned Professional Line of products for bassists.
A little history: In 2002, SWR debuted two new Professional Line amplifiers – the 350x and the 750x.
Both models offered a simple and straightforward solution for bassists who wanted the famous "SWR
Sound" in the simplest Professional Line package possible. Our top-selling Professional Line head rightout of the chute, the 350x (for example) started by featuring the renowned SWR tube preamp (using a
specially-selected 12AX7A vacuum tube), SWR's patented "Aural Enhancer," an easy-to-use 3-band EQ
section, and a high-quality, discrete solid-state power amp capable of delivering enough power andheadroom for most live applications.
Then, we added the new features that defined the "X Series." We integrated a new feature: our
SubWave™ circuit, which produces a tone an octave below the original signal and tracks as well or
better than anything else on the market today. (The effect is foot-switchable, and we provide afootswitch for your convenience.) The XLR (Balanced) output circuit was upgraded to include a variablepad, and is quieter in terms of signal-to-noise ratio. Additionally, the X Series amps were lighter, quieter(in terms of overall residual and white noise), and in our humble opinion, better-looking than previous
models thanks to a cosmetic rework from the ground up. With a proven track record among players of
all levels, the 350x and 750x have quickly become a constant presence in live venues and studios alike.
And, of course, each X Series amplifier is still assembled by hand and individually sound-tested in the
U.S.A. at our factory in Southern California.
So how did the 550x come about? We found that some folks wanted the combined feature sets of the
X Series amplifiers in one package. Some 350x enthusiasts wanted more power. Others interested inthe 750x preferred a two-rack-space configuration. We'll spare you the children's story, but we quickly
realized that, for people who wanted an easy-to-use, high-power, two-rack-space, SWR Professional Lineamplifier, the 550x would be "just right."
It's all part of SWR's commitment to continued improvement and refinement of even our most popularmodels, so that we can continue to assist today's bassist in the pursuit of the ultimate goal: finding
equipment that not only does the job, but actually enhances the overall musical experience andcontributes to the creative process. Everyone here at SWR sincerely hopes that the purchase of your550x helps you get there from here…and beyond.
Please take the time to read your Owner's Manual thoroughly and completely, so that you can realize thefull potential of your new 550x Bass Amplifier. Once again, thanks for your purchase, and for letting
SWR help Amplify Your Future.™
Sincerely,
SWR
NOTE:
NOTE Please take a moment to verify that the following items were included in your SWR 550x
packaging: AC Cable, SubWave Activator Footswitch, SWR Catalog.
550x OWNER’S MANUAL • 1

550x - FRONT PANEL FEATURES• Dual independent input jacks compatible with both passive and active instruments• Preamp Gain control with red LED clip indicator• Aural Enhancer control• SubWave™ Activator Switch (illuminated blue when engaged)• SubWave™ Level control• Bass control• Midrange Level control• Midrange Frequency control• Treble control• Effects Blend control (with pull-limiter-defeat option)• Master Volume control• Illuminated Neon Power On/Off switch

550x - REAR PANEL FEATURES• XLR Pad (Level) control• XLR Output jack
• XLR Mode switch (Direct, Direct + Sub, Line)• Ground/Lift switch for XLR Output jack• Tuner Out jack
• Side-Chain Effects Loop (Effects Send and Effects Return 1/4" jacks)• SubWave™ Activator Footswitch jack• Speaker Output mode switch• Two Speakon and two 1/4" Speaker Output jacks• Speaker Fuse (3AG, 10-amp fast-blo)• Line Fuse (3AG, 8-amp slo-blo)• AC Power Cord Receptacle

ELECTRICAL SPECIFICATIONSNOTE: All measurements were taken with a line voltage of 120VAC. All noise specifications are"unweighted." All voltages and watts are "RMS." All measurements are taken with tone controls set
flat, Aural Enhancer at minimum.
Power Ratings (minimum)
550 Watts @ 4 ohms
375 Watts @ 8 ohms
2 •550x OWNER’S MANUALFrequency Response (power amplifier)-3dB @ 20 Hz and 40 kHz
Sensitivity (full output under clipping, 8 ohms load, 100 Hz)
Passive Input Jack: 38 millivolts
Active Input Jack: 60 millivolts
Power Amplifier (Effects Return Jack "in"): 5 volts

Input Impedance
Passive/Active Input: 800k Ohms
Active Input: 60k Ohms
Effects Return: 27k Ohms

Output Impedance
Effects Send: 100 Ohms
Tuner Send: 100 Ohms
XLR (Balanced) Out: 750 Ohms

Signal To Noise Ratio-72 dB (<10 millivolts typical)

Equivalent Input Noise
9 microvolts

Dimensions (depth includes handles and XLR pad)
19" W x 5.38" H x 16" D

Weight26 lbs.

550x OWNER’S MANUAL •3

550x - GETTING STARTEDCONNECTING YOUR SPEAKER CABINETS
The 550x is a mono amplifier, which makes things fairly simple. Locate the "Speaker Outputs" section on
the rear of the amp. You will notice that there are four different speaker output jacks, two 1/4" type andtwo Speakon type jacks. The Speakon jacks are preferable if your speaker cabinet is equipped with
Speakons as well; however, you can use any of the four available jacks to connect your speaker(s) to
the 550x.
USING ONE SPEAKER CABINET
Using a speaker cable of 18 gauge or heavier (the heavier the cable, the lower the gauge), simply
connect any one of the 550x's Speaker Output jacks to the input jacks of your speaker cabinet. If yourcabinet is a 4 ohm enclosure, the 550x will deliver 550 watts into it. If your cabinet is an 8 ohm
enclosure, it will deliver 375 watts into it. Be sure to check the power handling capabilities of yourspeaker cabinet before connection and operation.

USING TWO SPEAKER CABINETS
Using a speaker cable of 18 gauge or heavier (the heavier the cable, the lower the gauge), simply
connect any of the 550x's Speaker Output jacks to the input jacks of your two speaker cabinets. (Youcan use one 1/4" and one Speakon Output jack each if you wish; however, it is always best to use
speaker cables with similar type ends.) If you use two 8 ohm cabinets–the two-cabinet setup
recommended by SWR–the resulting "total" impedance will be 4 ohms, and the 550x will deliver 550
watts spread across both cabinets. Since the 550x is a mono amplifier and individual cabinet levels
cannot be adjusted, it is recommended that you use cabinets of the same impedance when using morethan one cabinet. Needless to say, in all cases, be sure to check the power handling capabilities and
impedance of your speaker cabinet(s) before connection and operation.
IMPORTANT: The minimum total impedance when operating the 550x is 4 ohms. This means you cansafely use:a) a single 8 ohm cabinetb) a single 4 ohm cabinetc) two 8 ohm cabinets (total: 4 ohms)d) two 16 ohm cabinets (total: 8 ohms)
And you cannot safely use:a) one 8 ohm cabinet and one 4 ohms cabinet (total: 2.6 ohms)b) two 4 ohms cabinets (total: 2 ohms)c) one 2 ohm cabinet
More details are available in the "Speaker Outputs" section of this manual, and we strongly recommendthat you read the entire manual. However, this should be enough information to get you started.

TURNING THE UNIT ON
Remove the AC cable from the accessory pack and connect it from the amplifier to a standard walloutlet. Make sure that the both the Gain and Master Volume controls are set to the minimum position.
Locate the power switch on the right side of the front panel and turn the amplifier on. The power switch
4 •550x OWNER’S MANUAL

should then illuminate in red. Upon powering up, don't be surprised if you hear a small pop. This isabsolutely normal. (Eliminating this "power on transient" would require a component called a relay. SWR
chose not to incorporate this type of component due to the fact that relays degrade signal quality andoften fail, causing the unit to have no output and requiring a trip to a local service center. If you wish
not to hear the power on transient, simply set the Speaker Outputs mode switch to "Off" while turning
the unit on, and then set the switch back to "On" for normal operation.)

GETTING SOUND OUT OF THE 550x
Plug your instrument into the desired input jack (please refer to "Front Panel Features" for more detail).
Turn your instrument's volume up to at least 75% of maximum and slowly adjust up the Gain control.
Keep playing and turning the Gain control up until you see the Preamp Clip LED turn red. Then back off
the Gain Control about one large hash mark on the dial. Now turn up the Master Volume control to an
equal level. You should now hear the sound of your instrument amplified through the 550x into yourspeaker cabinet(s).

550x - FRONT PANEL FEATURESINPUT JACKS
Both input jacks accept a standard 1/4" phone plug and both inputs can be used at the same time.
Since the two inputs are totally independent, no loss in volume or tone will occur by using two
instruments simultaneously. However, the main applicational use for the two separate input jacks is theirdifference in level, as the Passive/Active input has five times more gain than the Active input. In otherwords, it's not necessarily intended as a "submixer" for two instruments, but no harm will come fromhaving two instruments plugged in at once. Please read below for more details.
PASSIVE/ACTIVE INPUT JACKThis input jack is designed to accommodate both "passive" instruments and most "active" instruments. A
passive instrument has no built-in preamp and does not use a battery, while an active bass utilizes abattery-operated preamp for gain, tone controls, or both. The Passive/Active Input will work with all
instruments having a maximum output of less than 1 volt RMS. Some active pickups such as EMG,
Bartolini, etc., use batteries for operation and will work perfectly using this input. Instruments made by
MTD, Sadowsky, Modulus, etc., have active electronics that are suited for use in the Passive/Active
input.
Generally speaking, try this input first. If you hear a small amount of distortion and the preamp clip LED
is not activated, try using the Active input jack. If the Active input does not correct any audible
distortion, check the battery in your bass.
NOTE:
NOTE If you would like to overdrive the first TUBE stage, this can be accomplished by using an
external preamp between your instrument and the Passive/Active input. To obtain optimum soundwhen trying this, make sure the preamp clip LED is not activated. If this occurs, turn down your Gain
Control until the LED does not light. The first preamp tube stage is NOT monitored by the preamp clip
circuit for this reason.
ACTIVE INPUT JACKThe Active input jack should be used with instruments having a built-in (on board) preamp or othersound sources that will produce output levels greater than 1 volt RMS. The number of bass
550x OWNER’S MANUAL •5manufacturers has increased significantly over the years, and it's impossible to try and keep track ofthem all. Generally, if you have very "hot" pickups and/or tone controls installed in your instrument, andyou use them to boost the level of your bass signal 10 dB or more, you may find the Active input morecompatible. The best judge is your own ears.
If you're using a keyboard or bass pedal with the 550x, we have found the best choice to be the Active
input.
NOTE:
NOTE Using the Active input with passive basses (active instruments will always employ a battery)
may result in a loss of high end transients. Players who roll off their high end starting at about 2kHz,or prefer a "darker" sound, may find this input more to their liking.
If you hear some distortion with your active bass and are using the Active Input, make sure the preamp
clip LED indicator is not lighting. If the preamp stage is not being driven into clipping, replace the battery
in your instrument.
GAIN CONTROLThe Gain control adjusts the volume of the preamp section. Since the Gain control is similar to a "pad,"a small amount of signal will be heard even with the Gain control rotated fully counter-clockwise ("MIN")
if the Master Volume is up.
After all EQ settings and the Aural Enhancer are set, the Gain control should be raised until the preamp
clip LED barely flashes when your loudest note is struck. This will insure maximum signal to noise ratio
and prevent unwanted clipping of the preamp section.
NOTE:
NOTE The Gain can serve as an EFFECTS SEND LEVEL ADJUSTMENT. If your effect is being
overdriven, turn down the Gain control and readjust your Master Volume for overall loudness.
PREAMP CLIP LED
The preamp clip LED will light whenever the preamp, tone section or output buffer reach clipping (runout of headroom). This function does NOT monitor the first tube stage of the Passive input. See that
section for more info.
In the event the clip indicator lights, turn down the Gain control. Since this circuit monitors the tone
controls, boosting any one of them can cause the clip LED to activate. Once again, you may leave thetone control at its desired level, but turn the Gain control down further.
NOTE:
NOTE Even though the Preamp Clip LED lighting indicates that at some point the preamp is clipping,no harm is being done to your amplifier. However, clipping of the power amp can cause damage toyour speakers and is not recommended.
AURAL ENHANCER
The Aural Enhancer is a feature that's been on just about every SWR amplifier since the company's
inception in 1984, and is a trademark part of the "SWR Sound" people have come to know and love. It
was developed to help bring out the fundamental low notes of the bass guitar, enhance the high-end
transients, and reduce certain frequencies that help "mask" the fundamentals. The ultimate result is:
1. A more transparent sound, especially noticeable when slapping and popping.
2. It can make a passive bass take on an "active" type of quality when set at positions of "2 o'clock"or further clockwise.
Let's take a second to learn how the Aural Enhancer works. Think of it as a variable tone curve thatchanges depending on where you set the Aural Enhancer control knob. As you raise the control
clockwise from the "MIN" position, you are elevating a whole range of sound (lows, mids, and highs) at a
6 •550x OWNER’S MANUAL

variety of frequency points selected specifically because they're different than those selected for theindividual Tone Controls.
This remains true up to about the "2 o'clock" position. This position–a favorite for many users–brings out
both the low end fundamentals and crisp highs and, at the same time, adds a little lower midrange tohelp cut through the band. However, if you go further clockwise and past the 2:00 position, selected
mids will start to drop off–specifically, a group of frequencies centered around 200 Hz. At this point andafter, the effect becomes much more pronounced. However, the curves involved here are gentle, as
opposed to the very extreme curves you can create by boosting or cutting the Active Tone Controls (EQ).
Most significantly for basses, the Aural Enhancer will help bring out the fundamentals of your lower
registers without masking them with overtones, as is possible when using the Bass control only. At thesame time, it opens up the sibilance characteristics of all instruments without being harsh.
Obviously, numbers and curves and circuits all mean nothing compared to what you hear with your own
ears. Play a chord, a repeated lick, or a harmonic, and turn the Aural Enhancer control to various points
on the knob to hear the effect for yourself. As always, your ears are the best judge when it comes tosettings that affect the tone of your instrument.
SubWave™ CONTROLS
Based on the circuit from SWR's groundbreaking Mo' Bass Soundstation, the SubWave™ on your 550x
is a lightning-quick sub-octave wave engine with tracking superior to other models of sub-octave effects
currently on the market. In plain terms, it hears the note you play and immediately generates a signal
one octave below it–all the way down to low 'C#', 'C', or even low 'B' on some basses!
SubWave™ ACTIVATOR SWITCH
Located directly above the SubWave™ Level Control, this is an illuminated push-button switch that
activates the SubWave™ effect. When engaged, the switch cap will illuminate in blue. Push once toengage, then again to disengage. (The SubWave™ effect can also be switched on and off via
footswitch; please see the heading titled "SubWave™ Footswitch" in the "Rear Panel Features" section
later in this manual.)
SubWave™ LEVEL CONTROL
Once the SubWave™ effect is engaged, you can use this control to determine the amount of effect tobe blended in with your original ("clean") bass signal. Turning the control clockwise will increase theamount of effect, while turning the control counter-clockwise will decrease the amount of effect.
When the control is set fully counter-clockwise to "MIN", no effect will be heard, even though theeffect is engaged and the Activator switch is illuminated in blue. This is normal. Also, when the control
is set fully clockwise to "MAX", the "clean" bass signal will still be present…along with plenty of
sub-octave effect. As always, your ears and the desired musical application will be the best judge insetting this control.
(Keep in mind that the Bass Level control will have a significant impact on the perceived level of the
SubWave™ effect as well, as it follows immediately after the SubWave™ in the signal chain. Please
read below.)

550x OWNER’S MANUAL •7

550x - ACTIVE TONE CONTROL SECTIONBASS CONTROLThe Bass control employs a shelving-type circuit and boosts or cuts the bass response + /-15dB, fromabout 30Hz to 100Hz. Starting at the control's mid-position ("center-click"), turning the control
counter-clockwise cuts the bass response, and turning the control clockwise boosts the bass response.
You'll find that the Bass Level control will boost or cut the SubWave™ effect along with the "clean" bass
signal. That's because of the range of frequencies covered by this particular control. You can use boththe Bass and SubWave™ Level controls to get a good balance between how much bass you want inyour clean sound, and how much of a bass boost you want when engaging the SubWave™. Some users
will want a significant boost, while others may be striving for a more consistent level (or "unity gain").
Again, let your ears and musical taste be the judge.
NOTE:
NOTE Setting both the Bass and SubWave™ Level controls near or at maximum boost will increase
the overall amount of bass in your signal VERY SIGNIFICANTLY! We're all in favor of that, just so longas your speaker cabinet can handle the peak levels. Adjust the controls slowly, and use common Z
sense.
MIDRANGE CONTROLSYour 550x comes equipped with two different controls for setting the amount of midrange present: onefor boosting and cutting the level of midrange, and another for setting the specific midrange frequency
that will be adjusted in level.
MIDRANGE LEVEL CONTROLThe Midrange Level control cuts or boosts the frequency set by the Midrange Frequency control.
Starting at mid-position, turning the Level control counter-clockwise cuts the desired tone. Turning
the Level control clockwise boosts the desired tone (set by the Midrange Frequency control). Whenthe level control is set at mid-position ("center-click"), turning the frequency control will have no effecton the sound.
To find the midrange area you are looking for:
1. Adjust the Midrange Level control to the full boost or cut position.
2. Rotate the Midrange Frequency control until the desired area you wish to cut or boost is found.
3. Adjust the Midrange Level control to the desired amount of cut or boost.
MIDRANGE FREQUENCY CONTROLThe Midrange Frequency control sets the area that is to be cut or boosted by the Midrange Level
control. If the Midrange Level control is set at mid-position, turning the Frequency knob will have NO
effect.
Some hints: If you need to "cut through" the band a little more, try boosting 200 to 400 Hz. If you
like a more transparent or "scooped" sound, try cutting at 800 Hz. The midrange controls areespecially useful in controlling fretless basses and their inherent qualities.
TREBLE CONTROLThe Treble control employs a shelving-type circuit and boosts or cuts the high frequencies (and theirsubsequent octaves) +/-15dB from about 2kHz to 14kHz. Starting at mid-position, turning the control

8 •550x OWNER’S MANUAL

counter-clockwise cuts the treble response, while turning the control clockwise boosts the treble
response.
EFFECTS BLEND CONTROLThe Effects Blend Control "blends" the signal sent from your instrument with the signal coming from your
EXTERNAL effects unit. (In other words, it has nothing to do with the SubWave™ effect onboard your550x.) With the Effects Blend fully counter-clockwise ("DRY"), no signal from your external effects unit
will be heard. As you turn this control clockwise, more of the effect can be heard in the overall sound.
When the Effects Blend control is set fully clockwise ("WET"), no true or unaffected signal is heard otherthan what your external effects unit provides. If your external effects unit has a similar control, adjust it
to the fully clockwise ("WET") position. This will avoid any possible phasing problems.
The Effects Blend circuit is similar to that used on recording consoles with the effects loop on a "sidechain" to the normal circuit. Unless the control is set to the full "wet" position, you will always get the fullsound of your instrument AND get the diversity an effects unit offers. This circuit is also effective in
reducing noise generated by effects units because it is located after the gain stages in the preamp.
The Effects Blend control functions only when the Effects Loop is being used. It is activated when a 1/4"
phone plug is inserted into the Effects Receive jack (for more information, please see the heading titled"Effects Loop" in the "Rear Panel Features" section later in this manual).
LIMITER/COMPRESSOR CIRCUITThe Limiter found in the 550x is a soft knee type limiter. The Limiter circuit is located after (post) the
Master Volume and before (pre) the power amplifier. Therefore, the Limiter is driven by the Master
Volume control. Its threshold (starting point) is preset by the factory so that the user can get maximum
overall apparent volume without unduly overdriving (or "clipping") the power amplifier, which caneventually damage the unit's internal circuitry. This can also be helpful in preventing speaker damage
when running your system at high volumes.
ACTIVATING OR DEFEATING THE LIMITER CIRCUIT
You may either activate or defeat the Limiter circuit via the Effects Blend control, which doubles as an
on/off switch for the Limiter. The "In" position activates the Limiter Circuit, and is the default setting as
shipped from the factory. To defeat the Limiter, simply pull "out" on the knob of this control until you
hear and feel a "click." To re-engage the Limiter, push the control back in to its original position.
LIMITER ACTIVE LED
When the threshold (starting point) of the Limiter circuit is reached, the Limiter Active LED will light,
indicating that the Limiter Circuit is active and helping to protect your power amplifier from clipping. The
Limiter LED will not illuminate when: a) the Limiter has been defeated by pulling out on the Effects
Blend control; b) when playing at levels not high enough to engage the circuit.
NOTE:
NOTE If you have defeated the Limiter and you hear a loud, sharp distortion present in yoursound–and the Preamp Clip LED is not lighting up–re-engage the Limiter by pushing the Effects
Blend control back in. If the distortion goes away, you were probably clipping the power amp, which is
not a good thing. Remember, the Limiter circuit is there to protect your amplifier from such a state ofoperation.

550x OWNER’S MANUAL •9

MASTER (VOLUME) CONTROLThe Master (meaning "Master Volume") control adjusts the level being sent to the power amplifier in your550x–it controls the overall volume of the unit. Turning the control counter-clockwise reduces the overalllevel, while turning the control clockwise boosts the overall level.
Two notes: The Master control never affects the level present at the various audio output jacks on therear panel–it only affects the level being sent to the power amplifier, and subsequently, your speaker
outputs only. Also, losses caused by external effects units can be recovered by increasing the Master
control.
POWER ON/OFF SWITCHThis switch turns the complete unit on or off. Setting the switch upwards to the "On" position turns on
the unit, and the switch itself will illuminate in red. Setting the switch downwards to the "Power" position
will turn the unit off, and the red light inside the power switch will turn off as well.

550x - REAR PANEL FEATURESBALANCED (XLR) OUTPUT
The Balanced XLR out is a true electronically balanced output, suitable for studio and "front-of-house"(live) mixing consoles. The level present at this output can be adjusted by using the XLR PAD CONTROL(see the "XLR Pad Control" section below for more details). The signal appearing at the Balanced Output
is governed by the setting of the THREE-POSITION XLR MODE SWITCH located directly below it(LINE/DIRECT/DIRECT + SUB).
In the DIRECT position, the Balanced Output signal comes from directly after the first stage of thespecially-selected 12AX7 preamp tube, giving you the sound of your instrument and some added
warmth. In other words, it becomes an active TUBE direct box. In this position, no front panel controls
are functional and the SubWave™ is not present.
In the LINE position, all front panel controls–including the Aural Enhancer, SubWave™, and EQ controls–are functional except the Master control, and the signal is essentially the same as that heard
through your speaker system. If you are using an external effects device in the effects loop, that signal
will also be present when in the LINE position (dictated by the setting of the Effects Blend control on
your 550x). When in this position, the output level will be affected by the Gain control on the front panel
as well as the XLR Pad control. It's worth noting that changing the level of the Gain control will affect thesignal present at your speakers, the Effects Send jack, and the Balanced Output, while the XLR Pad
control affects the level present at the Balanced Output only. For this reason, it's usually better to set
your Gain control in accordance with the directions in the "Gain Control" previously listed in the "Front
Panel Features" section of this manual, and to use the XLR Pad control to set the level specifically for
the Balanced Output.
The third position for this switch is the DIRECT + SUB position. In this position, the signal present at theBalanced Output jack is the same as when in the DIRECT position, with one important exception: the
SubWave™ is present. What's the benefit of this setting?
We've found that most people who use effects pedals prefer to use them in front of the amplifier. In
other words, they run their bass into the effect pedal's input, then from the effect pedal's output into thefront of their amplifier. In live applications where sound reinforcement is required, often times thefront-of-house engineer will take a direct signal from the bass itself (via either a direct box, or the
Balanced Output of your amp set to the DIRECT position) and use that signal as the main bass sound tothe house P.A. This way, if the bassist sets the amplifier's EQ controls in a way to his liking, but in a
10 •550x OWNER’S MANUAL

manner not conducive to a good bass sound for the house P.A., the front-of-house mixing engineer still
has a nice, flat bass signal to work with, and then he can EQ the bass sound for what's best in theroom. And, more relevantly, he would still get the sound of any effects pedal that was placed in front of
the amplifier.
The DIRECT + SUB position provides this exact function for the Balanced Output. It always contains thesound of your bass signal just after the first tube stage, and will also contain the SubWave™ effectwhen engaged without also sending EQ settings that may not be right for the house P.A. (or a studio
mixing console). You can always include all of your EQ settings (plus the SubWave) at the Balanced
Output by setting the three-position switch to the LINE position. But thanks to the DIRECT + SUB
position of this switch, it's not a necessity that you do so just because you want the SubWave™ present
at the Balanced Output.
NOTE:
NOTE You can still use the SubWave™ Level control to set the amount of sub-octave effect present
at the Balanced Output when in the DIRECT + SUB mode; however, it will also affect the level
present at the speaker outputs as well. Also, though the Gain control will not affect the level of the"clean" bass signal present at the Balanced Output when in DIRECT + SUB mode, it WILL affect thelevel of sub-octave present. This is normal, and occurs because the SubWave™ circuit is locatedafter the first stage of the preamp tube and is blended back into the signal specifically for thisspecial mode of the three-position switch. We recommend that you set the Gain and SubWave™
Level controls in accordance with previously mentioned instructions, and the gain structure should fall
into place fairly automatically.
Wiring for the XLR jack at the Balanced Output is as follows:
Pin 1 = ground, Pin 2 = + (plus), Pin 3 = - (minus)(American Standard)
NOTE:
NOTE Turn off transients appear at the Balanced Output when the amplifier is shut down. We
recommend that equipment being used in conjunction with the Balanced Output be turned down, off,or disconnected BEFORE the 550x is turned off.

XLR MODE SWITCH (LINE/DIRECT/DIRECT + SUB)
This three-position switch determines the signal present at the Balanced (XLR) Output jack as describedin the section directly above. In simple terms:
1. Direct = pre-EQ and SubWave™, post-first tube stage
2. Line = post-EQ and SubWave™
3. Direct + Sub = pre-EQ/post-first tube stage blended with SubWave™
Make sure the switch is set either to full left, full right or center to avoid an intermittent condition.

XLR PAD CONTROLThis control sets the level present at the Balanced (XLR) Output. Turning the control counter-clockwise
reduces the overall level, while turning the control clockwise boosts the overall level. It should be notedthat turning the control fully counter-clockwise to "Min" does not fully defeat the signal. This is normal,
as the XLR Pad is designed to provide a range of usable levels to be sent to a front-of-house or studio
mixing console.

550x OWNER’S MANUAL •11

XLR GROUND/LIFT SWITCH
Sometimes connecting to certain mixing boards or studio consoles with non-standard XLR wiring cancause a ground loop. Your 550x has a push-button switch for lifting the ground on the Balanced (XLR)
Output. (It affects no other outputs.) Pushing on the switch will change the mode of operation. Whenthe switch is in the "out" position (default setting from the factory), ground is on Pin 1 of the Balanced
Output jack as normal. When the switch is in the "in" position, the ground is lifted from Pin 1 of this
output. If a persistent hum exists after trying both positions of the ground lift, there is probably:
1. a bad cable or connection somewhere between your Balanced Output jack and the snake leading
to the mixing console
2. a dirty or miswired A/C socket
3. mis-wired or poorly wired A/C in the building
4. fluorescent lighting directly above you or in close proximity (especially when using single-coil pickups)
5. a cell phone in your right pocket that's interacting with the electronics in your bass (don't laugh,
this actually happens!)
But, in the case of a true ground loop, this switch can often times solve the problem.

TUNER OUT
The Tuner Out function allows the user to plug their instrument tuner into this jack and "tune up" without
having to unplug and go back and forth from amp to tuner. This feature is totally isolated from the restof the preamp and will function regardless of the settings on the front panel. Being isolated on a side
chain avoids loading down of the instrument, which can cause a loss in dynamic range.
To use this feature, connect a shielded patch cord from the Tuner Out jack on your 550x to the input
jack on your tuner. Turn the amplifier on and you're ready to go. If you do not wish to monitor yoursound during the tuning process, you may turn down the Master Volume.

EFFECTS LOOP (FOR EXTERNAL EFFECTS DEVICES)As mentioned previously in the "Effects Blend Control" section of the manual, the Effects Blend circuit inyour 550x is similar to that used on recording consoles, with the effects loop on a "side chain" to thenormal circuit. Unless the Effects Blend control is set to the full "wet" position, you will always get thefull sound of your instrument AND get the diversity an external effects unit offers. Use of the effects
loop will reduce the noise generated by external effects units (as compared to using the effect between
your instrument and the input jack, though many people use it in this fashion anyway). This is because
the loop is after the preamp gain stages.
The Effects Loop is compatible with most individual or multi-effect external effects devices. Many effects
devices on the market have input level adjustments. For instance, some units have a switch that you
can set for either -20 dB or +4 dB. In all cases, these should be set for 0 dB (if available) or +4 dB.
The level going to your effect is controlled by the Gain control on the front panel.
NOTE:
NOTE The Effects Loop is used in conjunction with the Effects Blend control on the front panel.
When the Effects Blend Control is in the full counter-clockwise ("DRY") position, no effects will beheard. This is normal.

12 •550x OWNER’S MANUALCONNECTING AN EXTERNAL EFFECTS DEVICE TO THE 550x EFFECTS LOOP
Obtain two high-quality shielded patch cables, preferably as short as possible. Route them in the mostdirect way possible. (Running patch cables over the top of the 550x–as with any amplifier–can induce
hum in the cables and is not recommended.) Take one cable and connect it from the EFFECTS SEND
jack on the 550x to the input of your external effects device. Take the second cable and connect it fromthe output of your external effects device to the EFFECTS RETURN jack on your 550x. To set levels,
follow the instructions as previously listed in the "Effects Blend Control" heading under "Front Panel
Features."And, just so there isn't any confusion, the Effects Loop has nothing to do with the SubWave™ effectonboard your 550x. It only is used in conjunction with an external effects device.

EFFECTS SENDThis jack's primary function is to send a post-EQ-and-SubWave™ signal to an external effects device foruse in the 550x Effects Loop. However, it can also be used as:
1. A line level output for use in conjunction with an additional (slave) power amp–such as SWR's
Power 750.
2. An unbalanced output suitable for recording or live mixing board purposes.
The output impedance of the Effects Send jack is 100 Ohms.

EFFECTS RECEIVE
This jack's primary function is to complete the Effects Loop circuit by routing the post-external-effects
device signal back into the power amp of the 550x, where it can be blended back in with the original
signal by using the Effects Blend control on the front panel. However, it can also be used as:
1. A power amp input jack. If, for some reason, you wished to bypass the entire front end and use
the 550x strictly as a power amp, you could take the output of whatever line-level audio source
you wished and connect it to this jack. Then, set the Effects Blend control to the full clockwise("WET") position. Use the Master control to set the overall level, and your 550x is now a power amp
only.
2. An input for pre-recorded music, for playing along and practicing purposes. To accomplish this,insert a CD player or other sound source into the Effects Receive jack. (It must be a MONO 1/4"
plug that goes into this input, so you'll have to use a stereo-to-mono cable adaptor of some kind.)
You can adjust the level of recorded music versus the "live" sound of your instrument by using boththe Effects Blend control (the more clockwise the control, the more pre-recorded music signal you'llhear) and the volume control of your CD (or other) audio source. The mixed sound will be heard
through your speakers. Besides pre-recorded music, this is also an excellent way to practice alongwith a drum machine.
Input impedance of the Receive jack is 27k Ohms minimum.
NOTE:
NOTE Inserting a plug into the Effects Receive jack activates the Effects Blend control. The control
receives this command through the ground created by the phone plug making contact with the jack.
The plug must be a mono plug (tip and ground). If you have a stereo plug only, it will be necessary totie the ring and the ground together.

550x OWNER’S MANUAL •13

SubWave™ ACTIVATOR FOOTSWITCHYour 550x comes equipped with the capability for hands-free control of the SubWave™ effect. To
achieve this function, locate the footswitch and 25-foot 1/4"-to-1/4" instrument cable included in your550x packaging. Connect one end of the cable to the output jack on the footswitch, and connect theother end to the SubWave™ Footswitch jack on the rear of your 550x. Turn the effect on and off bystepping on the switch; the illuminated switch above the SubWave™ Level control on the front panel
should alternate on (blue) and off, and the effect should engage and disengage accordingly.
A few notes: The type of switch contained inside the footswitch chassis is momentary, normally open.
Also, if you connect the footswitch to the unit while the unit is on, the SubWave effect may engage. This
is normal.

SPEAKER OUTPUTS MODE SWITCH
Setting the Speaker Outputs Mode Switch up to the "On" position allows the signal from the amplifier tobe heard through any speaker enclosure(s) connected to the Speaker Output section of the 550x.
Setting this switch down to the "Off" position disables the speaker output section. This feature allows
you to:
1. Use the Balanced (XLR) Output without using the internal speakers. This is especially useful inrecording when you are "miking" the speakers and only a direct signal is required for the moment.
2. Tune up without making sound onstage (and interfering with other band members) while using theTuner Out feature.
3. Defeat the "pop" you sometimes get when changing and/or unplugging instruments from the unit
(especially if you sometimes forget to disconnect your instrument cable from the amplifier before
disconnecting it from your bass, something that's always a good idea).
4. Defeat the "pop" present upon powering up the unit (though it causes no harm to the unit and/or
your speakers).

550x - SPEAKER OUTPUT SECTION
This section of the manual will deal with the proper connection of speaker cabinets to the power amplifier in the 550x. Some of this ground has already been covered in the Getting Started–ConnectingYour Speaker Cabinets section in the beginning of the manual. This is meant to supplement that section and provide information in greater detail, as power amplifiers, impedance and speaker cabinets are
all crucial in determining how best to operate your new 550x.

HOW IMPEDANCE AFFECTS POWER RATINGS
People often have questions about impedance. What is it? The root of the word "impedance" is the verb
"impede," which means to block or resist. That's what impedance is–resistance to power.
Power amps do not have a pre-determined impedance. They deliver power at whatever impedance thespeaker cabinet tells it to. That's why you hear the term "slave amp"–amplifiers only do what they're told.
So if someone tells you that they have a "4 ohm power amp," their terminology and understanding of
the concept is way off the mark.
Unlike power amps, every speaker cabinet has a pre-determined impedance rating measured in "ohms."
In most cases this rating is either 4 or 8 ohms (though there may still be some old 2 ohm creakers out
there). The higher the impedance of the speaker cabinet, the more resistance to power it will offer. The
14 •550x OWNER’S MANUAL

lower the resistance of the speaker cabinet, the less resistance to power it will offer. In other words,
HIGHER IMPEDANCE MEANS LESS POWER CAN ENTER THE SPEAKER CABINET. LOWER IMPEDANCEMEANS MORE POWER CAN ENTER THE SPEAKER CABINET.
You may be thinking that you've found the solution to the universe–just use speaker cabinets with really
low impedances and you can get skull-crushing power out of your amplifier, right? Wrong. There's acatch. Power amps have limits as to how low an impedance they can drive safely. This is what's known
as an amplifier's "Minimum Impedance Rating." If you try and operate a power amp below its minimum
impedance rating, it will give you lots and lots of power for about five minutes…and then overheat,short out and fail completely. In other words, THE LOWER THE OPERATING IMPEDANCE OF THE
AMPLIFIER, THE HOTTER IT WILL GET.

550x POWER AMPLIFIER MINIMUM IMPEDANCE RATINGS
Here's what this means to the power amp in the 550x. As mentioned previously, the 550x contains amono power amp, which makes things fairly simple. The Minimum Impedance Rating of the 550x is
4 ohms. This means that you can safely connect:- One 8 ohm speaker enclosure- Two 8 ohm speaker enclosures- Two 16 ohm speaker enclosures- One 4 ohm speaker enclosure
The number one enemy of any power amp is heat. We have listed the minimum impedance of the 550x
at 4 ohms so that the extraordinary amount of power available in this two-rack-space configuration is
not compromised by exposing the power amp to the additional heat that operation at 2.6 ohms or 2
ohms would generate. (SWR recommends that, when rackmounting your 550x, leave at least one open
rack space to allow for proper ventilation and cooling.) Consequently, damage to the power amplifier
section of the 550x may occur if speaker enclosures with total impedances less than the minimum
loads listed above are connected to the speaker output section. The owner's manual that came withyour speaker cabinet should state its total impedance. On SWR speaker enclosures, the total impedance is generally indicated on the speaker's input panel.
So how do you determine the total impedance of two cabinets hooked up to your 550x? Here's a quick
key of the two most common setups:
One 8 ohm enclosure + one 8 ohm enclosure = 4 ohms total impedance (OK)One 8 ohm enclosure + one 4 ohm enclosure = 2.6 ohms total impedance (not OK)
Here's another formula: To figure out the total impedance of two or more cabinets of equal value
hooked up in parallel, divide the impedance of one cabinet by the number of cabinets:
Impedance of one cabinet / number of cabinets = total impedance(For an even more in-depth discussion of impedance and power rating issues, go to the SWR website atwww.swrsound.com, click on "Products", then click on "Technical articles", then click on "Plug and Play Setup Tips for Amps and Speakers"–an article by SWR founder Steve Rabe that ran in the August '92
issue of Bass Player Magazine.)

550x POWER DELIVERY CAPABILITIES (POWER RATINGS)
After determining how the number of cabinets you wish to run affects the total operating impedance,
you need to take into account the power handling capabilities of your speaker cabinets as compared to550x OWNER’S MANUAL •15

what the 550x can deliver at that impedance. Those ratings are as follows:
550 Watts @ 4 ohms
375 Watts @ 8 ohms
So if you have two 8 ohm speaker cabinets, they will each get up to 275 watts of power, and moreduring transient peaks. A single 4 ohm cabinet will get 550 watts of power, and again, more during
peaks. Make sure your speaker cabinet(s) can handle the power.
Also be aware that when running the amp at 4 ohms with extreme settings on the Gain and Master
controls and the Limiter circuit disengaged, you may hear audible clipping of the power amp. If so, youhave exceeded the maximum capacity of the power amp. POWER AMP CLIPPING CAN CAUSE DAMAGE
BOTH TO ITSELF AND YOUR SPEAKER CABINETS. Either re-engage the Limiter (by pushing in on the
Effects Blend control) to help smooth out the peaks, or back off on the Gain and Master controls.
Remember, it's always better to have a little too much power than just barely enough. If you findyourself constantly wanting more power than the 550x provides, either:a) tell your bandmates to turn downb) tell the monitor engineer to turn you upc) (best option) take the time to investigate getting an external power amp and/or additional speakercabinets to supplement your rig.
One last time: The best two-cabinet setup is to use two 8-ohm enclosures.
NOTE:
NOTE The frequency response of the 550x is far greater than usually found in musical instrument
amplifiers (20 Hz to 40K Hz). This was engineered in order to give the bass player the same punch
and clarity on stage as found in the studio or concert P.A. systems. Therefore, it is doubly importantthat you are aware of the impedance and power rating of the speakers that you intend to use, andthat they are compatible with the 550x. Speakers that have been overdriven are easy to detect andgenerally do not fall under a manufacturer's warranty.

SPEAKER OUTPUT JACKS
Two 1/4" phone jacks and two Speakon Jacks (all wired in parallel) are provided for connection of the
550x to your speaker system. Whenever possible, use of the Speakon jacks is recommended. Speakon
jacks and connectors offer the best possible connection and are far superior to banana or 1/4" phonejacks in that they not only lock in place (preventing accidental disconnection), but also offer a greaterand more stable connection surface. This solid connection provides a more effective transfer of power
to your speakers.
Only SPEAKER CABLE of 18 gauge or heavier (the heavier the cable, the lower the gauge) should be
used to connect your 550x to your speaker system. Do not use shielded instrument cable to connect
your amplifier to your speaker enclosure, as this can result in intermittent power loss, cause your amp
to oscillate and damage itself and/or your speakers, and render the cable useless for any purpose.
NOTE:
NOTE Unlike some amplifiers on the market, the 550x can be used for recording purposes without
speakers attached to the speaker output jacks (using only the Balanced [XLR] Output).
Recommended single SWR Speaker enclosures for use with the 550x include:
Goliath III 4x10 (4 or 8 ohm versions)
Goliath Senior 6x10
Twelve-Stack 4x12
16 •550x OWNER’S MANUALBig Bertha 2x15
Megoliath 8x10Workingman's Tower 8x10
Recommended SWR Speaker combinations for use with the 550x include:(2) Goliath III 4x10's (8 ohm versions)(2) Goliath Junior III 2x10's (8 ohm version)(2) Son Of Bertha 1x15's(1) Goliath III 4x10 (8 ohm version) and (1) Son Of Bertha 1x15
(1) Goliath Junior III 2x10 (8 ohm version) & (1) Son Of Bertha 1x15
(1) Goliath Junior III 2x10 (8 ohm version) & (1) Big Ben 1x18
(1) Goliath III 4x10 & (1) Goliath Junior III 2x10 (8 ohm version)(1) Twelve-Stack 4x12 and (1) Twelve-Pack 2x12(2) Workingman's 4x10T's

SPEAKER FUSE
The speaker fuse is provided to protect your speakers in the unlikely event of a power amp failure or toprotect your power amplifier from incorrect speaker impedances or hookups. Size and rating of the fuse
is 3AG, 10 amp, fast-blo. Do not defeat the purpose of this feature by using a higher rated fuse as it
can damage your amplifier and void your warranty.
The fuse can open as a result of a fault in the speaker cable, the speakers themselves, or the power
amp being sent well into clipping. With this in mind, it is wise to carry extra fuses at all times.

LINE FUSE (A/C OR MAINS FUSE)
This fuse is provided to protect the internal electronics against power surges, etc. It also protects theunit against itself should one of the internal components fail. If this fuse should open, replace it withthe same type of fuse and rating. Do not defeat the purpose of this feature by using a higher rated fuseas it can void your warranty.
Proper size of the AC fuse for all countries is 3AG. Proper rating of the fuse is as follows:
United States: 8 amp slo-blo
Japan: 8 amp slo-blo
Europe (230V-240V): 4 amp slo-blo

A/C CORD RECEPTACLE
This receptacle accepts a standard A/C power cable (supplied with the 550x in the United States) usedwith almost all current musical, professional and household electronic devices. We recommend greatcare when packing up. If your unit is not in a rack case, put the cable in your instrument or accessory
case or leave it attached and looped around one of the rack handles. If it does become misplaced, areplacement cable can be purchased at almost any music or computer store.
NOTE:
NOTE The rating for this cable is 3 conductor, 10 amperes minimum. Look for this rating on thecable. Make sure the cable is plugged in all the way in both the amp and the wall socket.

550x OWNER’S MANUAL •17

INTERNAL FEATURE: VACUUM TUBE (VALVE)SWR installs a specially selected 12AX7A dual triode on the preamp circuitboard of every 550x. If thistube needs replacing, we recommend that you replace it with a similar high quality product. This tube
will need replacing only if it becomes noisy or microphonic (which sounds like glass tinkling in the
background of certain notes), or completely fails (causing no signal or signal at very low levels). The
tube in your 550x should last one to three years, depending on usage.

COOLING FAN
The power amp in your 550x is cooled by two methods: 1) an internal extruded aluminum heatsink; 2)
an internal fan. This fan runs constantly to ensure proper cooling of the amplifier at all times and cannot be defeated. Be sure to leave at least a 1/2" clearance between the vent on the sides of your 550x
and the sides of any rack case or enclosure in which you install your amp. This will allow for the heatgenerated by internal components to escape. SWR also recommends at least one empty rack space inyour rack to allow for the best possible airflow.
NOTE: It is normal for the cooling fan to be audible at low levels. In situations where absolute quiet isnecessary (such as in a recording studio when a cab is being miked), simply place the amplifier in a
separate room from the microphone being used for the speaker cabinet.

RACK MOUNTING INSTRUCTIONS
To preserve the beauty and reliability of your amplifier, we recommend that you install your amplifier in a
rack case. The 550x is completely ready to be rack mounted and needs no additional parts oraccessories other than the rack screws and the case itself.
The 550x takes up two full rack spaces (3 1/2"). If the rack in which you mount your 550x requires thatthe rubber feet on the bottom of the chassis be removed, please remember to keep the screws handy
in case you wish to reattach the rubber feet at a later date.
The 550x should be mounted as close to the bottom of the rack case as possible. If you must mountthe 550x in an area of the rack other than the bottom space, a piece of wood or similar solid material
should be installed between the bottom of the rack case and the bottom of the amplifier to prevent
flexing of the amplifier's chassis. Severe or constant flexing of the chassis can damage the amplifier andis not covered under the warranty.
Please do not forget about your amp after it has been installed in a rack case. Continuoustransportation and vibration can cause screws to become loose, both on the 550x and with your rackcase rails. We recommend that at least once a month you remove the 550x from the case and tighten
all outside screws and wipe off the outside of the chassis with a damp cloth. Then check all theconnections in your rack case and reinstall the unit.

A FEW WORDS CONCERNING HEAT
One of the most asked questions about our amplifiers is why they tend to get warmer than other amps.
The chassis of your amplifier can get quite warm during normal usage. This is especially true if you areoperating your 550x near maximum potential at a 4 ohm total impedance. This is because these low
impedances are introducing the least efficient condition of the unit (in terms of power drawn from the18 •550x OWNER’S MANUAL

outlet in relation to power produced in the speakers). The difference in these two figures can be as highas 300 watts. This would be the equivalent of putting a 300-watt light bulb inside a metal box, which
would obviously get quite hot.

Most musical instrument amplifiers on the market today use steel for their chassis, which does notconduct heat as well as aluminum. The 550x uses an all aluminum chassis and front panel because it
has less impurities than steel, is less susceptible to rust, and is a better conductor of heat. This resultsin the chassis acting as an additional heatsink, drawing heat away from heat-producing components
inside and thus extending their life. In this manner, we feel we have produced a more reliable amplifier,but at the same time, the outside of the 550x will get warmer than cases made out of steel.

The one condition you should be aware of is if one or more of the power amplifiers in your unit
becomes "over-biased." This condition can be recognized by turning your amplifier on and letting it sit"idle" (without speakers plugged in and without playing it). If your unit starts getting hot under these
conditions, it may be over-biased. This situation should be attended to and can be easily remedied inabout 15 minutes by a qualified service technician. A power amp can become over-biased throughcontinuous vibration or by any large jolt received in shipping, etc.

FINAL ENGINEERING SUMMARY
The two preamp gain stages utilize a specially-selected 12AX7A. The tone controls incorporate I.C.'s,
and the power amp is designed with extremely high quality bi-polar devices. Each type of device waschosen for its performance and reliability in the application used. The front panel and chassis of the
550x are comprised of aluminum, because of its superior electrical and thermal characteristics and lightweight. All primary electrical components are U.L. approved, and SWR uses Beldon Cable for all
shielded wire. All units are assembled by hand and individually soundtested in the U.S.A. at our factoryin Southern California.

SUGGESTED SETTINGS
The following page includes examples of tone control options for various styles of music. These settings
are intended for use as a starting point for dialing in your own individual sound, so feel free to makeadjustments based on your own playing style, instrument and speaker cabinet configuration. After you
find combinations you like, don't forget to try adding in the SubWave™…as much as you feel isnecessary.

550x OWNER’S MANUAL •19

SWR 550x – SUGGESTED SETTINGS

Aural
EnhancerminmaxMidrange
Bass

Level

Frequency

Treble

0

500

0

0

-15

+15

-15

+15

200

800

-15

+15

ROCK

Aural
EnhancerminmaxMidrange
Bass

Level

Frequency

Treble

0

500

0

0

-15

+15

-15

+15

200

800

-15

+15

REGGAE

Aural
EnhancerminmaxMidrange
Bass

Level

Frequency

Treble

0

500

0

0

-15

+15

-15

+15

200

800

-15

+15

JAZZ

Aural
EnhancerminmaxMidrange
Bass

Level

Frequency

Treble

0

500

0

0

-15

+15

+15

-15

200

800

-15

+15

SLAP

Aural
Enhancermin

STUDIO20 •550x OWNER’S MANUAL

max

Midrange
Bass

Level

Frequency

Treble

0

500

0

0

-15

+15

-15

+15

200

800

-15

+15

550x LIMITED WARRANTYThe SWR 550x from FMIC is warranted to the original consumer purchaser for TWO YEARS from thedate of purchase, against defects in materials and workmanship and provided that it is purchased froman Authorized SWR Dealer. This warranty applies only to products purchased in the USA or Canada.
This warranty is VOID if the unit has been damaged due to accident, improper handling, installation oroperation, shipping damage, abuse or misuse, unauthorized repair or attempted repair, or if the serial
number has been defaced or removed. FMIC reserves the right to make such determination on thebasis of inspection by an Authorized FMIC Service Center.
All liability for any incidental or consequential damages for breach of any expressed or implied
warranties is disclaimed and excluded herefrom.
Some states do not allow limitations on how long an implied warranty lasts, or the exclusion orlimitation of incidental or consequential damages, so that the above exclusion may not apply to you.
This warranty gives you specific legal rights and you may also have other rights which vary from state
to state.

SHOULD YOUR SWR AMPLIFIER REQUIRE SERVICE OR REPAIR,
PLEASE USE THE FOLLOWING PROCEDURE:

1
2

Locate your original receipt showing date of purchase, model and serial number.
Determine the closest Authorized FMIC Service Center to your location. The fastest way to get a complete list of
Authorized FMIC Service Centers is on the web, at:
http://www.mrgearhead.com/faq/allservice.html
You can also get this information by calling FMIC Consumer Relations at (480) 596-7195.

3

To receive warranty service, return the complete product to an Authorized FMIC Electronics Service Center, with proofof purchase, during the applicable warranty period. Transportation costs are not included in this Limited Warranty.

4

Defective products that qualify for coverage under this warranty will be repaired or replaced, at FMIC's discretion, witha like or comparable product, without charge.

For a complete list of Authorized FMIC
Service Centers, and the latest SWR
news, interviews, and more,check out our website:

SWR
8860 E. Chaparral Rd. Suite 100
Scottsdale, AZ 85250-2618 USA
PHONE: (480) 596-9690
FAX: (480) 367-5262
EMAIL: custserve@fenderusa.com
WEB: swrsound.com

swrsound.com

550x OWNER’S MANUAL • Part # 320045 • 03/03©2003 SWR

550x OWNER’S MANUAL •21