SM-900
USER GUIDE
SWR • CORONA, CA • USA
IMPORTANT SAFETY INSTRUCTIONS
CAUTION: 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 installation such 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 your electrician 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 damaged
2)If liquid has been spilled or objects have fallen into the product
3)If the product has been exposed to rain, water, or other conductive liquids
4)If the product does not operate normally by following the operating instructions
5)If the product has been dropped or damaged in any way
6)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 to determine 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.
SM-900 USER GUIDE
INTRODUCTION
The SM-900 is truly the “State of SWR’s Art” in bass amplification electronics. The SM-900 is only slightly deeper and heavier than the SM-500, yet delivers twice the power and includes new features such as our very flexible tone section. Along with shelving-type Bass and Treble controls, the equalization section consists of two independent 3-band semi-parametric EQs. This provides the user with two analog presets via a silent footswitch, or three presets (EQ 1, EQ 2, or EQ 1+2) using the manual slide switch located on the front panel. You can now go from a solid groove sound to soloing with just the tap of your foot. Several suggested EQ settings are included in the tone section of this manual.
The SM-900 also boasts a studio-oriented “side chain” effects loop allowing the user the diversity of an effects unit while maintaining the constant clarity and natural tone of the instrument. SWR’s exclusive “To Tuner” jack is also on a side chain. Remember when you had to unplug your bass from your amp and hook into your tuner and frantically tune up between songs? Or patch the tuner between your instrument and amp, thus degrading sound quality? Those times are history.
Add to the above both stereo and mono effects loops, stereo/mono operation of the power amps, biamp capabilities, up to 900 watts RMS of power, an extremely quiet preamp, a “non-pumping” limiter, complete recording ability, and SWR’s proven reliability and sound quality, and you have what we feel is the best bass amplifier made anywhere in the world.
Every Professional Series product from SWR Sound Corporation is manufactured and hand-built in Sun Valley, California, USA.
SM-900 USER GUIDE • 1
SM-900 SPECIFICATIONS
Note: All measurements were taken with a line voltage of 120VAC. All noise specifications are “unweighted.” All voltages and watts are “RMS.”
POWER (minimum):
Bridge/Mono Mode
900 Watts @ 4 Ohms
650 Watts @ 8 Ohms
440 Watts @ 16 Ohms (minimum load = 4 Ohms)
Stereo Mode (per side)
400 watts @ 4 Ohms
240 watts @ 8 Ohms
144 watts @ 16 ohms (minimum load = 2 Ohms)
FREQUENCY RESPONSE (power amplifiers): –3dB @ 20 Hz and 40kHz
SENSITIVITY (full output, 8 ohm load, 100 Hz):
Passive Input Jack: 50 millivolts
Active Input Jack: 200 millivolts
Power Amplifier (Effects Return Jack “in”): 1.6 volts
INPUT IMPEDANCE
Passive/Active Input: 800kohms
Active Input: 60kohms
Effects Return: 27kohms
OUTPUT IMPEDANCE
Effects Send: 100 ohms
Tuner Send: 100 ohms
XLR Balanced Out: 750 ohms
Crossover High and Low Outs: 100 ohms
SIGNAL TO NOISE RATIO: –75 dB (< 8 millivolts typical)
EQUIVALENT INPUT NOISE: 8.9 microvolts
DISTORTION:
Power Amplifiers (Effects Return jack “in”): 0.03% THD
I.M. Distortion: 0.06 %
System Distortion (gain & master volume full, Aural Enhancer at min., tone controls flat): 0.4 % THD
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THERMAL PROTECTION:
Both natural convection and thermostatically controled forced air (cooling fan). The internal fan is set to operate when the heatsink reaches 50 degrees centigrade and will automatically shut off upon cooling. This allows silent operation in the studio or other low volume conditions.
COUPLING CAPACITORS IN SIGNAL PATH (input to output jacks):
Quantity: 5
Type: High-grade metallized polyester, made in Germany
TUBE COMPLEMENT: One (1) specially-selected 12AX7 vacuum tube (valve).
CHASSIS MATERIAL: All aluminum for light weight and purity. Steel-reinforced rack corners.
ASSEMBLY: Virtually every step of the assembly procedure of the SM-900 is done by hand, inhouse, at SWR Sound in Sun Valley, California, USA.
CUSTOM PARTS: The chassis, extruded heatsinks, printed circuit boards, power transformer, owners manual and shipping cartons are all manufactured in California. Our custom rotary potentiometers are made by Noble, Japan.
SIZE (measured from the rack ears back): 19" W x 3.45" H x 13.75" D (482.6 x 37.63 x 349.25 mm)
WEIGHT: 22 lbs. (9.98 kg)
FRONT PANEL FEATURES & OPERATING PROCEDURES
EQ FOOTSWITCH JACK
For remote selection of the equalizers, insert the footswitch that came with your SM-900 into this jack. Installing the footswitch will automatically DISCONNECT the manual EQ slide switch located directly above the Aural Enhancer.
Depressing the footswitch will silently select the settings you have decided upon on either EQ bank 1 (bottom row, white knobs) or EQ bank 2 (top row, black knobs). Each bank consists of 3 bands of semi-parametric equalization featuring dual concentric knobs. The INNER knob adjusts cut and boost, and the OUTER knob is for selection of frequency. When you have selected EQ 2 (top three bands), the RED LED located just to the left of these will light. When this LED is OFF, EQ 1 is active. This LED lets you distinguish which band of EQ you are currently using from a distance. EQ 1+2 is NOT obtainable with the footswitch.
The BASS and TREBLE controls are INDEPENDENT of either the footswitch or the manual EQ slide switch. (See “Tone Controls” for further details.)
Disconnecting the footswitch will automatically re-activate the manual slide switch.
INPUT JACKS Passive/Active Input
A “passive” instrument has no built-in preamp and does not use a battery. An “active” bass, on the other hand, utilizes a battery operated preamp, either for gain, tone controls, or both. Although labeled “Passive,” the Passive input jack will work with all instruments that have a maximum output of less than 1 volt RMS.
Generally speaking, try the Passive input jack first. If you hear a small amount of distortion and
SM-900 USER GUIDE • 3
neither the preamp clip LED or the power amp clip LED are activated, try using the Active input jack.
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 input. To obtain optimum sound when trying this, make sure the preamp clip LED is not activated. If this occurs, turn down your Gain control. The first preamp tube stage is NOT monitored by the preamp clip circuit for this reason.
Active Input
The Active input jack should be used with instruments having a built-in (on board) preamp that will produce signals over 1 volt RMS. Basses with really “hot” pickups may be more compatible with the Active input. Let your ears be the judge.
If you are using a KEYBOARD or BASS PEDAL, etc., with the SM-900, we have found the best choice to be the Active input.
Note: Using the Active input with passive basses 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 jack, check your battery. Also, make sure none of the overload indicators are lit. This will save you or your service technician time and aggravation.
GAIN CONTROL
The 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 rotated fully counter-clockwise (with the Master Volume up).
After all EQ settings and the Aural Enhancer are set, the Gain control should be raised until the preamp clip LED barely flashes upon striking your loudest note. This will insure maximum signal-to- noise ratio and prevent unwanted clipping of the preamp section.
Note: The Gain control serves as an effects send level adjustment. If your effect is being overdriven, turn down the Gain control and re-adjust your Master Volume for correct, overall loudness.
This control also drives the Limiter circuit. If you are not getting enough effect from your limiter, turn up the Gain control, but be sure to keep an eye on the preamp clip LED.
PREAMP CLIP LED
The preamp clip LED will light whenever the preamp, tone section or output buffer reach clipping (run out of headroom). This function does NOT monitor the first tube stage of the Passive input (see “Passive Input” above for more info). In the event the clip indicator lights, turn down the Gain control. Since this circuit monitors all three tone sections (bass, treble, EQ 1 and EQ 2) independently, boosting any one of these controls can cause the LED to activate. (In the case of EQ 1 or EQ 2, even with the unselected EQ bank.) So, for instance, if you notice the preamp clip indicator lighting, but hear no distortion and are using EQ 1, switch to EQ 2 to see if it is the culprit (or vice-versa).
Naturally, if you want to overdrive the preamp section for a distorted tone, ignore the preamp clip LED, but, be very cautious of the POWER AMP CLIP LED as any clipping at this power level can damage your speaker system.
AURAL ENHANCER
SWR's Aural Enhancer Control was developed to bring out the fundamental low notes of the bass
4 • SM-900 USER GUIDE
guitar, reduce certain frequencies that help mask the fundamentals, and enhance the high end transients. Basically a tone-shaping control, 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 via the Aural Enhancer Control. Exact frequencies affected are dependent on the characteristics of the instrument used.
TONE CONTROLS AND EQUALIZATION: A BASIC PRIMER
The flexibility of the tone and EQ sections of the SM-900 is one of the most elaborate we have developed. They have the ability to correct “dead” and “hot” spots that may be inherent in your instrument, poor room acoustics, and can bring life to old strings, correct peaks or dips in speaker systems, and best of all, bring out the sonic qualities of your instrument and YOUR playing technique. Although at first glance the number of controls and variables may seem fairly complicated, once you get acquainted with how to use and apply them, they will open doors you never thought possible.
First, let’s put everything into three groups: the Aural Enhancer; Bass and Treble; and one section of the 3 band semi-parametric EQ. Start with the Enhancer at minimum and the Bass, Treble and EQs set flat (mid “click” position). (The INNER knob of the 3-band parametric sets “flat” position.) At a comfortable listening level, run through scales using different positions on the neck—prefer- ably one near the headstock, at about the 5th fret, and up near the twelfth. Were all the notes even? Did some notes seem alive and others dead? Does your open E string and the octave on the twelfth fret sound too similar?
Play and sustain an open “E” note, then play the octave on the twelfth fret. Now repeat this process with the Aural Enhancer shifted from minimum to maximum. You should now hear a discernible difference between these two notes with probably a little more brilliance. You should also be able to “feel” the open “E” better, too.
Repeat the process once again. After playing the octave on the 12th fret, rotate the Enhancer from maximum to 12 o’clock. As you rotate the Enhancer counter-clockwise, you will hear a midrange “growl” added to the sound. For your info, this growl is at about 160Hz and 320Hz.
With this one adjustment, you have added dynamic range and clarity for slapping, and added midrange for finger style playing. The best setting of the Enhancer for optimum results while slapping and playing finger style will depend on your fingers, instrument and speakers.
Listening to these settings may lead you to wanting a little more “bite” in the slap sound. Rotate the Treble control clockwise from its center click position until you’re satisfied. The Treble control should not have as much effect on the finger sound. Go from lows to highs with the slap technique. If the lows don’t have quite the “punch” or “body” to round out the desired dynamics, boost the Bass control from its center click position until it is well-balanced. Of course, if you have too many highs or lows, reverse this process.
Listen closely once again, both to the slap and finger sounds. The bite of the highs in the slap is good, but there may be an irritating sharpness. One area that may be particularly irksome is at about 1.5k to 2kHz. Go to the third band on EQ 1. Make sure the EQ slide switch is in the EQ 1 position (far left). If your footswitch is plugged in, make sure the LED next to EQ 2 is not lit. Turn the frequency knob (the one on the outside) on the third band so that the pointer is set at about 2 kHz (8 o’clock). Turn the level control (the one in the middle) from mid position to approximately –6 dB (9 o’clock). If the irritation is gone but the presence is still there, you may need to boost the Treble slightly to maintain crispness.
OK, you’ve got the high end of your slap sound perfect. The lows and mids still could use some work. Being a perfectionist, you want the impact of a hard-hit snare riding on the wave of a kettle
SM-900 USER GUIDE • 5
drum! You want to wake up the guitar player who’s been drilling your ears with his Marshall all night!
Turn to the FIRST band of the semi-parametric EQ. Set the frequency knob to approximately 60Hz (9 o’clock). Boost the Level control to about +6 dB (3 o’clock). This should provide the air and impact to carry the notes. To clean up the midrange, adjust the frequency control of the middle band on EQ 1 to 800 Hz (3 o’clock). Adjust the Level control to –8 dB (8:30). All things being fairly equal, you should have a great slap sound, with dynamics, impact, and clarity.
Go back to finger-style. It may be too thin-sounding and the notes are not “even,” with some being quite loud and others hardly audible. Flick the EQ select switch to EQ 2 (far right). The LED to the left of the first band should now be lit. Your original finger tone set with the Enhancer, Bass and Treble should still be intact, for the most part.
Since finger styles are so vastly different from player to player, as opposed to a slap style, it is fairly hard to direct the user to specific frequencies with cut and boost parameters. Instead, we will give you several tones (frequencies) for you to experiment with as suggested by some of our noted professional users:
Jimmy Haslip: 80 Hz (first band), +10 dB; 200 Hz & 400 Hz (2nd band), + 2 dB; 1kHz (3rd band), +8 dB
Ricky Minor & Neil Stubenhaus: 40 Hz, +3 dB; 250 Hz, + 4 dB; 1kHz, +3 dB
Charles Frichtel: 100 Hz, +6 dB; 600 Hz, +5 dB; 2.5kHz, –4 dB
Michael Manring: 120 Hz, –2 dB; 1kHz, –6 dB; 6kHz, +2 dB
Dean Cortez: 120 Hz, +5 dB; 600 Hz, +3 dB; 1kHz, +5 dB
Try using each group by itself. As you try them, make a note of the frequencies that are pleasing to your ear and the ones that aren’t. Then, make up your own group. Once you’re finished, plug in your footswitch, stand a few feet from your speakers, turn it up a little, and play a few slap licks with EQ 1 activated. Then switch to EQ 2 and play a groove.
TONE CONTROLS AND EQUALIZATION
EQ SELECT SLIDE SWITCH
This switch allows you to manually select either EQ 1 (far left position), EQ 2 (far right position), or EQ 1+2 (middle position).
To activate the bottom 3 bands of semi-parametric EQ, select the EQ 1 position. To activate the top three bands, select the EQ 2 position. The LED will light at this position, indicating it is active. We did not provide an LED for EQ 1 as this could confuse you from a distance. So, if the LED is lit, you’re using EQ 2. If it is not, you’re using EQ 1 or EQ 1+2. Remember, you cannot select EQ 1+2 with the footswitch, just one or the other.
When EQ 1+2 is chosen with the slide switch, all 6 bands of equalization are active. Because the two bands are in parallel with each other, there are two conditions to be aware of in the EQ 1+2 mode: there will be a +4dB boost in overall gain; and cut and boost will be ±7 dB, as opposed to ±15 dB. Normally, if two bands were both set to the same frequency, and both boosted +15 dB for a total of +30 dB, “motorboating” (low frequency oscillation) or feedback (high frequency oscillation) could occur and damage speakers. For this reason, and the fact that more than 15 dB of boost or cut is rarely required, we chose this configuration. If you should require more than the 7 dB offered for any one band in the EQ 1+2 mode, set two bands at the same frequency and boost or cut both of them for a total of 15 dB.
6 • SM-900 USER GUIDE
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