750x OWNER’S MANUAL 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.
INTRODUCTION Congratulations on your purchase of the SWR 750x Bass Amplifier! You now own a killer combination of massive power, easy-to-use controls, simply integrated onboard effects… and pure SWR tone. A little history: The SWR 750x is an upgraded version of the Bass 750, a model we’ve offered since 1999 in response to demand for an amp that delivered the punch and volume of classic high-powered amplifiers, coupled with the sound and clarity SWR is known for.
750x – 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 • Overdrive Activator Switch (illuminated red when engaged) • Overdrive “Drive” Control • Overdrive Level Control • SubWave™ Activator Switch (illuminated blue when engaged) • SubWave™ Level control • Bass control (with Pull Turbo function) • Midrange Level control • Midrange Frequency control • Treble control (with Pull Tra
Frequency Response (power amplifier) (@ 850 watts RMS) –3dB @ 20 Hz and 40 kHz Sensitivity (full output under clipping, 8 ohms load, 100 Hz) Passive Input Jack: 62 millivolts Active Input Jack: 267 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 Dimensions (depth includes handles and XLR pad) 19" W x 5.
Important: The minimum total impedance when operating the 750x is 2.6 ohms. This means you can safely use: a) A single 8 ohm cabinet b) A single 4 ohm cabinet c) Two 8 ohm cabinets (total: 4 ohms) d) One 8 ohm cabinet and one 4 ohm cabinet (total: 2.6 ohms) ** e) Three 8 ohm cabinets (total: 2.6 ohms) ** **Running the amplifier constantly at 2.6 ohms, while technically acceptable, will cause the amp to run hotter than usual, and will cause heat-related wear on components sooner than normal.
when 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 Jack The Active input jack should be used with instruments having a built-in (on board) preamp or other sound sources that will produce output levels greater than 1 volt RMS.
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 to help 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 and after, the effect becomes much more pronounced.
tion with the level of the clean “Channel One.” How do you control the level of “Channel One?” By using the Gain Control, which controls the level of the clean bass signal in the preamp. Also, the EQ Controls are located after the Overdrive circuitry, so they can have a drastic effect on the distorted tone. (The treble control is especially useful for adding or removing a nasty edge to your Overdrive sound.
Pull Turbo Pulling the Bass Control knob to the “out” position widens the bandwidth of the bass control, and changes the center-point frequency from 80 Hz to 40 Hz. It has the effect of more clearly enunciating frequencies down to 30 cycles (low “B” on a five string bass). Often these notes can be felt more than heard, so you may want to re-check the Preamp Clip LED, and listen for power amp clipping or speaker distor tion as well.
The Effects Blend circuit is similar to that used on recording consoles with the effects loop on a “side chain” to the normal circuit. Unless the control is set to the full “wet” position, you will always get the full sound 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.
Power On/Off Switch This 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. 750x – REAR PANEL FEATURES Balanced (XLR) Output The Balanced XLR out is a true electronically balanced output, suitable for studio and “front-of-house” (live) mixing consoles.
Wiring for the XLR jack at the Balanced Output is as follows: Pin 1 = ground, Pin 2 = + (plus), Pin 3 = – (minus) (American Standard) 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 750x is turned off.
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: The Effects Loop is used in conjunction with the Effects Blend control on the front panel.
Preamp Out This jack provides another audio output, but it is located later in the signal chain than the Ef fects Send jack. This signal is post-EQ AND post-effects loop, but still before (pre) the Master Volume control. You should use this jack when using an effects device in the effects loop and wish to achieve: 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.
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 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.
750x 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 to what the 750x can deliver at that impedance. Those ratings are as follows: 850 Watts @ 2.6 ohms 750 Watts @ 4 ohms 450 Watts @ 8 ohms So if you have two 8 ohm speaker cabinets, they will each get up to 375 watts of power, and more during transient peaks.
Recommended single SWR Speaker enclosures for use with the 750x include: • Megoliath 8x10 • Goliath Senior 6x10 • Big Bertha 2x15 • Henry The 8x8 • 12-Stack 4x12 • Workingman’s Tower 8x10 Recommended SWR Speaker combinations for use with the 750x include (all are 8 ohm models): • (2) Goliath III 4x10s • (2) 12-Stack 4x12s • (2) Son Of Bertha 1x15s • (1) Goliath III 4x10 & (1) Son Of Bertha 1x15 • (1) Goliath III 4x10 & (1) Big Ben 1x18 • (1) Goliath III 4x10 & (1) Goliath Junior III 2x10 Speaker Fuse The sp
RACK MOUNTING INSTRUCTIONS To preserve the beauty and reliability of your amplifier, we recommend that you install your amplifier in a rack case. The 750x is completely ready to be rack mounted and needs no additional par ts or accessories other than the rack screws and the case itself. The 750x takes up three full rack spaces.
750x LIMITED WARRANTY The 750x from SWR is warranted to the original consumer purchaser for TWO YEARS from the date of purchase against defects in materials and workmanship, provided that it is purchased from an Authorized SWR dealer. This warranty applies only to products purchased in the USA or Canada.
