FAQ

Have a question about SWR^® amplification? You might find the answer here on the FAQ page. If you don't see your question addressed below, click here to email your question to SWR.

General questions
Amplifiers
Speakers
Features
Connection
Service

GENERAL QUESTIONS

Q: What do the initials "SWR" stand for?
A: They're initials of the company's founder and chief designer—Steve W. Rabe.

Q: Does Fender^® own SWR?
A: SWR was purchased by FMIC^® (Fender Musical Instruments Corporation^®) in 2003.

Q: What has Fender done with SWR? Are SWR amps "Fenderized" now?
A: FMIC purchased SWR to increase their offerings to the bass community and to offer dealers more choices when stocking their stores. There was no interest in changing anything about the "SWR sound". The SWR and Fender brands have very different tones, aesthetics and "vibe", and have co-existed on retail floors for decades, so we feel there is room for both to co-exist in the same corporate family.

Having said that, great pains were taken when production moved into the Fender facilities. Several key employees remained with SWR and have integrated into the FMIC manufacturing facilities, teaching others how to build SWR along the way. The original SWR designs and circuits have been carefully reconstructed and documented to keep the sound and performance intact.

Although SWR and FBA^® (Fender Bass Amplification) necessarily share some resources, they have separate Marketing, Artist Relations and, of course, Electronics R&D teams. There is a good deal of friendly competition within the offices, which we feel helps to make both brands better.

Q: Where are SWR amplifiers manufactured now?
A: The country of origin is usually specified on the back panel of your SWR product but, in general, the Professional Series products are built in Corona, California; the WorkingPro and Acoustic Series products are built in Ensenada, Baja California, Mexico; and the LA Series is manufactured in Indonesia.

Q: I don't understand some of the technical terms used in relation to amplifiers and speakers. How can I learn more?
A: A comprehensive list of technical terms and definitions can be found in the SWR Glossary.

Q: My rig isn't loud enough, do I need more power?
A: To effectively double the volume heard by the human ear, it would be necessary to increase the power output rating of the amplifier by a factor of 10. A more effective way to increase the volume from your system is to add additional speakers. Speakers move air, and the movement of air creates pressure in a room. This as commonly known as "sound pressure," and it is measured in decibels (dB).

Decibels are measured in a logarithmic fashion not unlike the Richter scale. If you are reading 103 dB on a meter and you increase the volume to 106 dB, you've effectively doubled the perceived volume. By adding speakers, you're moving more air, thereby increasing apparent volume.

There's an interesting phenomenon known as "coupling gain," which happens when like speaker cabinets are placed next to each other or on top of each other, causing them to "couple" and creating a situation where the whole becomes greater than the sum of the parts. You get a "free" 6 dB of gain when the cabinets are placed together. If you normally play at or around 100 dB and you place an identical cabinet on or next to the original, you will more than double the volume perceived by the human ear. Split the cabinets, and you'll hear the volume decrease.

Q: My high-power amplifier doesn't seem to produce as much volume as I would expect. What gives?
A: It is a fact of life in the musical equipment industry that one manufacturer's 500-watt rating may be completely different from another's. Think of it as a variation of "Your Mileage May Vary" in the auto industry.

Here's the deal: It takes more power—a lot more power—to drive low frequencies than it does to drive high frequencies. When the amplifier specs are calculated, a commonly used test frequency is 1kHz (1,000 cycles per second). This means that the complete waveform travels 1,000 times in a second, producing a relatively high frequency. If an amplifier can deliver 500 watts at 1kHz, then advertising this amp as a 500-watt amp is not a false statement. The real question is about how many watts it does delivers at full bandwidth, or, in other words, all of the frequencies between 20 and 20,000 cycles (note: all SWR amplifiers deliver full 20 Hz to 20 kHz bandwidth). The fundamental frequency of the low "E" on a bass guitar is around 41.3 Hz. This is a large waveform, and it requires a substantial amount of power to amplify it at high volumes. When you ask an amplifier to reproduce lower frequencies, the amplifier becomes less efficient and therefore produces fewer watts. Realistically, an amplifier should be rated at several different frequencies in order to give an accurate representation of its power-producing capabilities.

An amplifier manufacturer will often put a filter on the amp that doesn't allow it to reproduce frequencies below a certain point. This typically makes the device more efficient and therefore capable of producing a higher wattage specification. In the case of a bass amplifier, if the filter was set at, for example, 20 cycles, then a 30-cycle (low "B" on a five-string bass) fundamental frequency could be reproduced. If the filter was set at 40 cycles, the low "B" fundamental could not be accurately reproduced, although the first harmonic at 60 cycles would sound OK. By placing a "high pass" filter on an amplifier, a manufacturer can publish higher wattage specifications that in reality are misleading because the frequencies the amp can reproduce fall short of the range of the intended purpose.

Another common way to bump up an amplifier's wattage specification is to show the wattage rating at a low impedance. The most common impedance that musical instrument amplifiers are designed to drive is probably 8 ohms (although a 4-ohm impedance is almost as common). Because an amplifier delivers a higher wattage output at lower impedances, it's not uncommon to see an amplifier advertised as 500 watts at 2 ohms. What does this mean at 4 ohms or 8 ohms? Less power!

Make sure that you learn more than what is painted on the front panel of an amp or is included in an advertisement if you're truly interested in the power-producing capabilities of an amplifier. One model's 500 watts may not be the same as another's 500 watts. Check the specs.

Q: How does my SWR compare to a similar model by another manufacturer?
A: Although we maintain an awareness of music product trends, SWR is not in the habit of comparing our systems to those of other manufacturers (we're happy to leave that to online newsgroups and music product review sites). At SWR, we focus on our own design ideas and on offering the best-sounding amplification possible. We offer comprehensive information on the SWR product line on this website so that potential customers can make an informed decision as to which product will best meet their needs.

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AMPLIFIERS

Q: I have a mono amplifier*. Should I use the speaker outputs on the rear panel of my amplifier to connect my speaker enclosures, or connect a speaker cable from the head to cab #1 and then a speaker cable from cab #1 to cab #2?
A: There is no advantage one way or the other, as both methods produce the same result—a parallel connection that delivers the same amount of power to each speaker enclosure (given that your enclosures have the same impedance). For the sake of simplicity, we generally recommend connecting each enclosure directly to the speaker outputs on the amplifier.

* SWR amplifiers that fall into this category include: 350x™, 550x™, 750x™, Baby Blue Head™, Workingman's^® 2004, Workingman's 4004, Workingman's 8004, WorkingPro™ 700, WorkingPro 400, Bass 350™, Basic 350™, Studio 220™ and SS 180™

Q: Can I use both instrument inputs on my SWR amplifier at the same time?
A: Yes; however, in some instances, doing so can result in phasing problems caused by the characteristics of the instruments being used. If you need to connect more than one instrument (second bass guitar, drum machine, etc.), there are several ways to do so. These include:

Q: When I turn my SWR amplifier's power switch to the "On" position, I hear a "pop" sound through my speakers.
A: This may be the top concern among owners of older model SWR amplifiers. Although many users consider the "pop"—a transient heard at power-up—to be disconcerting, it is normal and will not damage your loudspeakers.

If you wish to avoid hearing the power-on transient, the following actions may be taken:

Q: When I turn my SWR amplifier's power switch to the "Off" position, the LEDs on the front panel light up and flicker. Is there something wrong with my amplifier?
A: No. It's normal for the front panel LEDs to illuminate and flicker momentarily during power down because the amplifier's power supply is discharging. It does not indicate any type of internal problem or malfunction.

Q: What type of tube is in my amp, and when should it be replaced?
A: There is one 12AX7 found in the preamp section of all Professional Series SWR amplifiers (this excludes the Workingman's^®, LA, and Acoustic series amplifiers, and the ST-800 and Power 750 Power Amplifiers). Tube replacement may become necessary after one to three years depending on usage and care. Generally speaking, tubes don't need to be replaced unless they become noisy or microphonic.

Q: What make and type of preamp tube can I use for replacement?
A: Any make of 12AX7 (also known as ECC83 or 7025) can be used as a replacement preamp tube in your SWR amplifier. ECC83 is the European number; 7025 is the military number.

Different "cousins" of the 12AX7 will affect gain structure in different ways. The 12AX7 will provide 100-percent gain. Using a 12AU7 would result in a loss of about 40 perecnt of gain. Obviously, less gain will affect how your preamp reacts. SWR amplifiers are designed to operate in a specific fashion, with a specific gain structure that is best achieved by utilizing the 100-percent gain of the 12AX7.

Q: I'm moving to a different country. How do I change the voltage of my amplifier so that it's compatible?
A: If you plan to use an SWR amplifier that was purchased in North America in a country outside of North America, it will be necessary to change the unit's voltage so that it's compatible with the foreign country's electrical system (as with any electronic product you intend to use overseas). SWR amplifiers purchased in North America are designed to run on 120 volts; foreign current is generally 220 volts.

If you want the voltage of your amplifier changed permanently (for a relocation or long-term move), we recommend that you have a replacement power transformer installed in the unit's chassis. This modification can be made by any qualified Authorized FMIC Service Center. If you would like to permanently convert the voltage of your amplifier by replacing the internal power transformer, click here to locate an Authorized FMIC Service center near you.

Please note: SWR Professional Series models built before March 1999, feature multi-tap transformers and can be wired for 110v, 120v, 220v or 240v. A schematic for this purpose may be ordered from SWR by calling 480-596-7195.

Q: I do a lot of touring and am back and forth between countries with different voltage requirements. What should I do?
A: As with any electronic product that you intend to use overseas, if you plan to use an SWR amplifier that was purchased in North America in a country outside of North America, it will be necessary to change the unit's voltage so that it's compatible with the foreign country's electrical system. SWR amplifiers purchased in North America are designed to be run on 120 volts; foreign current is generally 220 volts.

If it will be a temporary situation (such as a tour) for which you require the amplifier to run on a voltage other than 120 volts for a short period of time, we recommend the use of an external voltage converter (or step up/down transformer). Voltage converters are available from your local or online electronics retailer and are offered in various wattage capacities, generally ranging from 100 to 10,000 watts. It is important that the capacity of the voltage converter be equal to or greater than the current draw of the amplifier (see requirements below). On SWR amplifiers, the current-draw specification is generally listed below the AC cord receptacle on the amplifier's rear panel. Depending on the model, it may also be necessary to change the amplifier's line fuse. Please consult your amplifier's owner's manual for the correct fuse rating.

Q: Can I use my SWR bass amplifier as a guitar amp?
A: Yes. Although SWR bass amplifiers are designed primarily for use with electric bass guitars, they are perfectly capable of amplifying standard electric guitars. Simply make sure that you adhere to the set-up and operation instructions found in your owners manual.

Q: Can I use my SWR acoustic amplifier as a bass amp?
A: Yes. Although SWR Acoustic Series amplifiers are designed primarily for use with acoustic instruments, the California and Strawberry Blonde combos are perfectly capable of amplifying electric instruments. If you plan to do so, simply make sure that you adhere to the set-up and operation instructions found in your owners manual.

Q: Can I use my SWR acoustic amplifier with electric guitar?
A: Yes. Although SWR Acoustic Series amplifiers are designed primarily for use with acoustic instruments, the California and Strawberry Blonde combos are perfectly capable of amplifying electric instruments as well. If you plan to do so, simply make sure that you adhere to the set-up and operation instructions found in your owners manual.

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SPEAKERS

Q: My speaker cabinet sounds "tinny" and the sound doesn't have any body to it. Turning up the volume makes it sound even worse. What's the deal?
A: Your speakers are probably "out of phase." This occurs when a speaker cabinet is miswired, resulting in one or more of the speakers traveling in a different direction than intended, often causing signal cancellation in the lower frequencies. For instance, a 2x10 speaker cabinet that is out of phase would have one speaker cone traveling outward and one travelling inward, resulting in little or no sound. Use a 9-volt battery and the following procedure to determine whether or not your speakers are wired out of phase:

Q: What type of speakers are used in SWR speaker enclosures?
A: Speaker sizes and makes vary by model. Individual specifications and makes can be found on the product page for each SWR speaker enclosure or combo.

Q: What is the impedance, power handling, frequency response, etc., of my SWR speaker enclosure?
A: Individual model specifications can be found on the product page for each SWR model.

Q: I've been told that it's better to overpower rather than underpower my speaker enclosure(s). Is this true?
A: Although this idea has become increasingly popular, we don't recommend applying more power to your speaker system than it is designed to accept. Exceeding the power handling capacity of your speaker enclosure is considered misuse and can render your warranty null and void in the event of any damage to your loudspeakers.

Underpowering your speaker system by too great a margin can be dangerous, too. Constant clipping of the power section of even a 100-watt amplifier (to get greater apparent volume than the amplifier can effectively produce) can damage speakers rated to handle much greater wattage. "Clipping" is the distorted signal generated by an amplifier that is being operated over its capabilities, and describes the actual "cutting off" of signal peaks at the amplifier's power limit. This is the sound often heard when a system is played too loud and the sound starts to "break up." Clipping distortion is the most common source of speaker damage, due to the near-DC content present in a clipped waveform. Those unaware of this may assume that they can turn their volume control up to maximum because their speaker system is rated to handle significantly greater wattage than their amplifier is rated to deliver. As explained above, this is simply not the case and should be avoided.

The best overall solution is to assemble a system of components that are equally or closely matched in terms of power rating/handling. For example, an amplifier with a power output of 500 watts RMS at 4 ohms connected to two 8 ohm speaker enclosures, with a power-handling capacity of 250 watts RMS each, would be considered a well-matched and recommended system.

Q: Can I change the impedance of my SWR speaker enclosure?
A: It's possible but not recommended. SWR speaker enclosures are designed to function and perform properly using the wiring schemes and stock components installed at the factory. As SWR neither offers nor recommends modifications to its speaker enclosures, wiring diagrams for such procedures are not offered. Please note that modifying your SWR product will void your warranty.

Q: I have two SWR cabs purchased years apart. The speaker grills are different and I'd like them to match. Can I buy a replacement grill?
A: Replacement speaker grills are available; however, SWR only stocks currently-in-production speaker grills. Older grill styles are not available. For information on price and availability, please contact the FMIC Consumer Relations Department, 480-596-7195.

Q: I don't have a cover for my speaker cabinet. How can I keep it clean?
A: SWR recommends using a stiff brush (such as those used for cleaning dishes) to keep SWR cabinet carpeting free of lint and dust, although the best way to keep your cab clean is to get an SWR cover. Waterproof covers made from high-quality Cordura are available for most SWR products and may be ordered through your local SWR retailer.

Q: I live in a very cold climate and need to store my speaker cab for the winter. Should I be concerned about the effects of cold on my cab?
A: Drastic temperature changes can effect speaker performance, so exposing your cab to very cold weather for extended periods of time is not recommended. If you must keep your cab or combo in your car's trunk or in your garage during extremely cold weather, make sure that you allow enough time for your speakers to return to room temperature before playing through them.

Q: I saw a flash of light coming from inside my cabinet and now it sounds different. What happened?
A: The protection circuit for the horn found in older SWR models such as the Goliath™ (I & II), Triad™, and Goliath Junior™ (I & II)™ enclosures actually includes a light bulb wired in series with the horn. Under normal conditions, the bulb is cool. As you begin to overload or put more power into the horn, the bulb begins to light and increase in resistance, limiting the voltage going to the horn. At high power levels, you may notice intermittent light coming from behind one of your speakers. This means that the protection circuit is doing its job and that you should probably turn down the attenuator knob. A sudden burst of feedback or a heavily clipped waveform can cause the bulb to open just like a fuse. Replacement bulbs are available and nearly all auto parts stores and gas stations (usually sold as auto "dome" lights; replacement bulb No. 211-2 is manufactured by companies including Sylvania, Phillips and Wagner).

Q: I think I may have blown the tweeter in my SWR speaker enclosure. How can I verify this and where can I find a replacement?
A: To test the tweeter, first, without plugging in an instrument, connect your amplifier to your speaker cabinet as you would normally, then turn the amplifier's power switch to the "On" position. Rotate the treble and master volume controls to maximum, at which point a loud hiss from the tweeter should be audible. Rotate the tweeter attenuator control back and forth and listen for increase (clockwise) and decrease (counter-clockwise) in volume of the hiss.

If you don't hear any change as you sweep the attenuator control, you may have either a blown tweeter diaphragm or a fried attenuator "L-Pad." A blown tweeter diaphragm is more likely, so you should order either a replacement diaphragm for the horn or a replacement piezo tweeter depending on the model of SWR speaker enclosure that you own. Please contact your local SWR retailer or any Authorized FMIC Service Center to order replacement parts.

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FEATURES

Q: What is the Aural Enhancer™, and what does it do?
A: The Aural Enhancer is a passive R/C network that alters the frequency response throughout the bass spectrum. This pre-shaping is "blended" into the original signal through the Aural Enhancer Control. Exact frequencies affected are dependent on the characteristics of the instrument used. Basically a tone shaping control, the Aural Enhancer was developed to bring out the fundamental low notes of the bass guitar, to reduce certain frequencies that help mask the fundamentals and to enhance the high-end transients.

The Aural Enhancer has been featured on nearly every SWR amplifier since the company's inception in 1984; it is a trademark part of the "SWR Sound" people have come to know and love. The ultimate result is a more transparent sound (especially noticeable when slapping and popping), and it can make a "passive" bass sound "active" when set at or above the two o'clock position.

To understand how the Aural Enhancer works, think of it as a variable tone curve that changes 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 variety of frequency points selected specifically because they're different than those selected for the individual tone controls.

This remains true up to about the two o'clock position. This position, a favorite for many users, brings out the low-end fundamentals and crisp highs. At the same time, it adds a little lower midrange to help cut through the band. However, if you go further clockwise past the two o'clock position, selected mids will start to drop off—specifically, a group of frequencies centered around 200 Hz. At this point and after, 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 the same 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 to settings that affect the tone of your instrument.

Q: What is the Bass Intensifier™?
A: A proprietary feature on many SWR amplifiers designed after 2003; the Bass Intensifier is a low-end boost circuit combined with a smooth, fast-acting compressor. The Bass Intensifier provides radical low frequency boost without overdriving the amplifier, which can be useful for heavier sections of a song - or just for "fattening up" the overall tone of your bass.

Q: What type of limiter is in my amp and how does it work?
A: The limiter found in the Bass 350™, Silverado™, SM-900™, Workingman's^®, WorkingPro™, and the X-Series is a soft-knee type limiter. The circuit is located after (post) the master volume and before (pre) the power amplifier. The circuit is driven by the master volume control. It's threshold (starting point) is preset by the factory so that the user can get maximum overall apparent volume without unduly overdriving the power amplifier. The limiter in the older SM-400 and ST-220 differs according to its position in the circuit and the fact that it is continually adjustable.

Q: The limiter LED lights when I play. Am I damaging my amplifier or speakers?
A: The limiter LED lights when your signal has reached the limiter threshold in order to let you know that the limiter circuit has been activated. No harm is being done to your amplifier or speakers when this LED lights or stays lit; in fact, the limiter is actually helpful in preventing speaker damage.

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CONNECTION

Q: I don't have a speaker cable. Can I use an instrument cable to connect my amp to my speakers?
A: No. Using instrument cables to connect your speakers can result in intermittent power loss, amp oscillation and speaker damage, as well as rendering the cables useless for any purpose. We recommend using 18-gauge or heavier speaker cables.

Q: Can I run my amp without any speaker cabinets connected to it?
A: Yes. All SWR amplifiers can be used for recording purposes using only the XLR record out and without speakers attached to the speaker jacks. This is unlike most amplifiers found on the market.

Q: Do I have to use the banana jack or Speakon connector when running in bridge mode?
A: Yes. Please see the back panel operation diagram in your owner's manual for correct speaker connection procedures.

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SERVICE

Q: Where can I find an owner's manual for my SWR?
A: You can find both plain text and/or PDF versions of most SWR owner's manuals available for free download on this website, in the "products" section. Hard copies of SWR owner's manuals are available for $5 each, plus shipping and handling. To order, contact the FMIC Consumer Relations Department, 480-596-7195.

Q: Where can I order replacement parts for my SWR?
A: Replacement parts can be ordered directly from your local SWR retailer or any authorized FMIC Service Center.

Q: How can I order a schematic?
A: To request a schematic, please provide your full name and mailing address (or fax number), along with the model and serial number of your amplifier. Send your request to swrcustserve@fender.com, or contact the FMIC Consumer Relations Department, 480-596-7195.

Q: My amplifier doesn't seem to be working properly. What should I do?
A: If you are experiencing issues with your amplifier that you believe are abnormal, you should arrange to have your amplifier bench-tested by a qualified technician. A complete list of authorized SWR service centers can be found in the Service section of this website.

Q: I think I might have blown a speaker. What should I do?
A: First, get your cabinet to an Authorized FMIC Service Center. Click here to locate a Service Center near you, or contact the FMIC Consumer Relations Department, 480-596-7195. For non-warranty speaker reconing, please contact:

Audio Design And Service
10764 Vanowen St.
N. Hollywood, CA 91605
818-754-0467

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