Ampeg B3 Bass Amplifier User Guide
- June 1, 2024
- ampeg
Table of Contents
Owner’s Guide
for the
B3 / B328 / B3158
Bass Amplifier
Made in the U.S.A. by
An Introduction to your new Ampeg Bass Amplifier
Thank you for making one of the best choices you will ever make for your musical career – choosing one of the finest bass amps available, an Ampeg B3/B328/B3158.
Your new bass amplifier offers many outstanding features. One hundred fifty watts of pure bass energy, total tone control, and rugged construction make each a true performer’s bass amp.
Features
In the world of high performance bass amps, Ampeg amplifiers stand alone. In true Ampeg tradition, your new B3/B328/B3158 offers you more power, performance and flexibility than any other bass amplifier in its class. The outstanding features of your new amplifier, features which set it apart from the competition, are listed below:
- 9-BAND GRAPHIC EQ: Use as a “second channel” for bass solos, or to shape the sound to your own exacting standards. An independent level control lets you adjust the Graphic EQ volume
- BALANCED LINE OUTPUTS: Independent level control. XLR type jack to patch into house consoles, mixing boards, or external power amplifiers
- EFFECTS LOOP: Connect your effects here for increased intensity and quieter operation
- DRIVE CONTROL: To add harmonics for tube-like overdrive
- BALANCE CONTROL (B3158 only): To fine tune the mix between the Biamp High and Biamp Low outputs
Important Safeguards and Precautions
All Ampeg products are designed for continuous safe operation, as long as common sense is used and steps are taken to help avoid certain problems. Abiding by the following rules can help prevent damage to your amplifier, yourself and others.
- The amplifier is equipped with a three-pronged AC power cord. To reduce the risk of electrical shock, NEVER remove or otherwise attempt to defeat the ground pin of the power cord.
- Connect the amplifier ONLY to a properly grounded AC outlet of the proper voltage for your amp.
- Avoid sudden temperature extremes, rain and moisture. Also, avoid sudden and intense impact. (If the unit has been subjected to any of the preceding abuses, have it looked at by an authorized service center.)
- NEVER set the amplifier on a support that might give out under its weight.
- Whenever using tall or stacked speaker cabinets, use them ONLY on a level surface. NEVER set tall or stacked cabinets on a surface with more than a five degree incline since tipping or falling could occur, possibly causing serious injuries.
- Always keep the total speaker impedance at or above the rated load.
- Unplug the amplifier before cleaning it. NEVER spray liquid cleaners onto the amplifier. Wipe it with a slightly dampened, lint-free cloth to remove dirt and film.
- Don’t use the amplifier if it has sustained damage to the chassis, controls, or power cord. Refer the unit to an authorized service center for inspection.
- Amplifiers capable of producing high volume levels are also capable of inflicting permanent hearing loss or damage, if the exposure to such levels is prolonged. Such damage is progressive and irreversible!
|
CAUTION
|
---|---|---
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER.
NO USER-SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
THIS EQUIPMENT HAS BEEN DESIGNED AND ENGINEERED TO PROVIDE SAFE AND RELIABLE OPERATION. IN ORDER TO PROLONG THE LIFE OF THE UNIT AND PREVENT ACCIDENTAL DAMAGES OR INJURY, PLEASE FOLLOW THESE PRECAUTIONARY GUIDELINES:
WARNING: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT OPEN CHASSIS; DO NOT DEFEAT OR REMOVE THE GROUND PIN OF THE POWER CORD; CONNECT ONLY TO A PROPERLY GROUNDED AC POWER OUTLET.
CAUTION: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.
CAUTION: NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
CAUTION: OUR AMPLIFIERS ARE CAPABLE OF PRODUCING HIGH SOUND PRESSURE LEVELS. CONTINUED EXPOSURE TO HIGH SOUND PRESSURE LEVELS CAN CAUSE PERMANENT HEARING IMPAIRMENT OR LOSS. USER CAUTION IS ADVISED AND EAR PROTECTION IS RECOMMENDED IF UNIT IS OPERATED AT HIGH VOLUME. The chart below shows the U.S. Government Occupational Safety and Health Administration (OSHA) regulations which were in effect at the time of this publication for permissible noise exposure, per 29CRF1910, Table G-16.
SOUND LEVEL dBA
SLOW RESPONSE
| DURATION PER DAY
IN HOURS
---|---
90|
8
92
| 6
95|
4
97
| 3
100|
2
102
| 1-1/2
105|
1
110
| 1/2
115|
1/4 or less
According to OSHA, any exposure in excess of those listed above could result in some hearing loss.
EXPLANATION OF GRAPHICAL SYMBOLS:
= “DANGEROUS VOLTAGE”
= “IT IS NECESSARY FOR THE USER TO REFER TO THE INSTRUCTION MANUAL”
The Front Panel Controls and Their Use
1. INPUT: The signal output from an instrument (active or passive) or a line level signal may be connected here by means of a shielded instrument cable.
2. -15dB PAD: This switch, when depressed, attenuates the input signal by 15dB. Attenuation allows the Gain control (#4) to be used in a more usable (higher) position. If clipping is indicated with the Gain control at a low setting, attenuation is needed.
3. PEAK LED: This LED flashes when the signal level into the preamp approaches clipping. Adjust the Gain control (#4) until a strong signal from your instrument causes this LED to flicker.
NOTE: If the LED flashes frequently with the Gain at a low setting, use the -15dB pad (#2) to attenuate the input signal and readjust the Gain.
4. GAIN: This serves as the input level control for the amplifier. For the best signal to noise ratio set this control so the Peak LED (#3) flashes when you strike a string fairly hard.
5. DRIVE: This control is used to overdrive the preamp in order to get various harmonic enhancement or distorted sounds. In the fully counterclockwise position the preamp is in the cleanest condition. As the control is rotated clockwise, signal level is increased to drive the preamp harder (into distortion). The tone of the signal is also changed to provide a smoother overdrive. (The tone controls may have to be readjusted to obtain the overall desired tone.) The Gain control (#4) and -15dB Pad (#2) interact with the Drive control. For greater overdrive, the Pad switch should be out and the Drive control fully clockwise. Use the Gain control to set the amount of overdrive desired. The Peak LED (#3) will illuminate steadily when the amp is used in this manner.
6. BASS: This is the primary low frequency control which allows for 12dB of cut or boost at 50Hz.
7. ULTRA MID: This is the primary midrange control. Rotate this control to the left of center for a “contoured” sound (more distant, less midrange output) or to the right of center for a pronounced (more up-front) tone.
8. TREBLE: This is the primary high frequency control which allows for 22dB of cut or 17dB of boost at 5kHz.
9. EQ ON LED: This LED illuminates when the EQ is turned on by either the Master Control (#11) or a footswitch (#24, rear panel).
10. GRAPHIC EQ: These sliders control the output frequencies indicated above each control. The center position of each control is flat (no boost or cut).
11. MASTER: Set the overall output level of the amplifier with this control. Pulling this knob out actives the Graphic EQ (#10). When a footswitch is connected (#24, rear panel) this switch is disabled.
12. BALANCE (B3158 only): This control proportions the output signal between the low and high frequency output jacks (see #18, rear panel) when using the amp in the biamp mode.
13. LIMIT LED(S): The LED illuminates whenever the amplifier is near full output, indicating that the internal limiter is keeping the output from distorting.
NOTE: There are two Limit LEDs only on the B3158: one for its low frequency power amp and one for its high frequency power amp.
14. POWER ON LED: This LED indicator illuminates when the POWER switch (#15) is ON.
15. POWER SWITCH: This heavy-duty rocker switch applies the power to the amplifier. The amp is ON when the top of the switch is depressed, OFF when the bottom of the switch is depressed.
The Rear Panel
16. FUSE: This protects the unit from damage due to overload conditions or power line surges. In case of failure, replace it only with the same size and type.
17. AC LINE IN: Firmly insert the supplied AC power cord into this socket until it is fully seated. Plug the male end of the cord into a grounded AC outlet. DO NOT DEFEAT THE GROUND PRONG OF THE AC PLUG!
18. SPEAKER OUTPUT(S): This section is different for each of the three models. The B3158 is shown in the illustration above.
The B3158 has two internal amplifiers, one for the high frequencies, one for the low. Each amplifier section has its own speaker output jack, factory-wired to the internal speakers. To use external speaker cabinets, unplug the connectors from the jacks and use speaker cables with 1/4” plugs to connect the LOW jack to your low frequency cabinet and the HIGH jack to the high frequency cabinet. Use the Balance control (#12, front panel) to proportion the output signal between the low and high frequency output jacks. Observe the minimum impedance ratings for each output (8 ohms for high, 4 ohms for low).
The B3 has a single speaker output jack (wired at the factory to its speaker enclosure). To use an external speaker cabinet, disconnect the amplifier from the enclosure and connect it to the external cabinet, using a speaker cable with 1/4” plugs. Observe the 4 ohm minimum impedance rating.
The B328 has a single speaker output jack, and two input jacks on its speaker cabinet: WITH TWEETER and WITHOUT TWEETER. Connect the speaker cable to the jack which gives you the best sound. To use an external speaker cabinet, disconnect the amplifier from the enclosure and connect it to the external cabinet, using a speaker cable with 1/4” plugs. Observe the 4 ohm minimum impedance rating.
The following chart shows the total impedance load when connecting speaker cabinets in parallel:
Cabinet Impedance
| # of Cabs| Total Impedance
---|---|---
8Ω| 2|
4Ω
16Ω
| 2| 8Ω
16Ω| 4|
4Ω
19. EFFECTS RETURN: To use an external effects device or other signal processor, connect the OUTPUT of the device to this jack using a shielded cable. This returns the processed signal into the amplifier’s master section.
20. EFFECTS SEND: Connect the output from this jack to the INPUT of an external effects device using a shielded cable. This sends a post-EQ signal to your effects. Since plugging a cable in here does not break the through connection to the power amp, this jack can also be used as an unbalanced line out jack.
21. PRE/POST SWITCH: You can select either pre or post-EQ for the signal at the Balanced Out jack (#23) with this switch. With the switch in the OUT position, the signal at the jacks will be pre-EQ. This is a direct output which is not affected by any EQ or boost settings. With the switch depressed, the signal is post-EQ and is controlled and modified by the tone controls, Graphic EQ and Effects Loop.
22. -20dB SWITCH: This switch adjusts the output level at the Balanced Out jack (#23). The switch works independently from the front panel Master control. Depressing the switch activates the -20dB pad, which allows patching into a mixer’s mic input without overdriving it.
23. BALANCED OUT: This XLR-type connection supplies a balanced preamp output signal for connecting to a house mixing board, recording console or external amplifiers with balanced inputs. The signal can be set to pre or post-EQ by the Pre/Post switch (#21). The level can be adjusted for either mic or line type inputs using the -20dB switch (#22).
24. FOOTSWITCH: This jack accepts the 1/4” plug from a 1-button footswitch, allowing remote control of the Graphic EQ on/off function. When a footswitch is used, the front panel Master Pull EQ On switch (#11) is bypassed.
Some Suggested Settings*
ROCK:
The setting of the Gain control depends on your particular instrument.
JAZZ:
The Master control should be set to produce the appropriate output volume level.
COUNTRY:
The Graphic EQ can be used to tailor the amplifier to your speaker cabinets, to compensate for room acoustics and to “fine tune” your sound.
FUNK “POPPING:”
Troubleshooting
In the unlikely event that your B3/B328/B3158 should malfunction, take a few minutes to troubleshoot it before you call for service. You can save yourself time and money by doing it yourself, and often the cure for the problem is something quite simple.
If the problem isn’t covered above, or if the steps lead you here, then contact your Ampeg dealer for service information. Also, you should refer your amp for servicing if it gets dropped, has liquid spilled into it, or sustains damage to its power cord (see page 2).
System Block Diagram
- INPUT
- -15dB PAD
- GAIN
- PEAK LED
- DRIVE
- BASS
- ULTRA MID
- TREBLE
- FOOT SWITCH
- EQ ON
- MASTER
- POST
- EFFECTS RETURN
- EFFECTS SEND
- PRE
- BALANCED OUT
- LIMIT LED
- POWER AMP
- SPEAKER OUT
- LOW LIMIT LED
- LOW FREQ POWER AMP
- LOW SPEAKER OUT
- HIGH LIMIT LED
- HIGH FREQ POWER AMP
- HIGH SPEAKER OUT
- BALANCE
Technical Specifications
OUTPUT POWER RATING|
---|---
B3, B328:
| 150 Watts RMS, 4Ω load
B3158:
| Low Freq – 100 Watts RMS, 4Ω load
High Freq – 50 Watts RMS, 8Ω load
POWER REQUIREMENTS| 120VAC, 60Hz, 170VA
100/115VAC, 50/60Hz, 170VA
220-240VAC, 50/60Hz, 170VA
TONE CONTROL RANGE|
Bass:
| ±8dB @ 50Hz
Ultra-Mid:
| +5, -17dB @500HZ
Treble:
| +17, -22dB @ 5KHZ
GRAPHIC EQ RANGE| ±11dB @ 40Hz; ±8dB @ 80, 150, 300, 600, 900, 2kHz;
±9dB @ 9kHz
GAIN| 66dB typical, tones @ center
SIGNAL TO NOISE RATIO| 75dB typical
INTERNAL SPEAKERS| B3| B328| B3158
Low Frequency:|
Size/Type:
| 15” Ampeg Custom (1)| 8” Polypropylene (2)| 15” Ampeg Custom (1)
Magnet:
| 56 oz| 30 oz| 56 oz
Voice Coil:
| 2.5”| 1.5”| 2.5”
Impedance:
| 4Ω| 8Ω| 4Ω
High Frequency:|
Size/Type:
| N/A| Hi-Efficiency Piezo (1)| 8” Polypropylene (1)
Magnet:
| | | 30 oz
Voice Coil:
| | | 1”
Impedance:
| | | 8Ω
SIZE AND WEIGHT
(W x H x D)
| B3| B328| B3158
20”x26”x13.5”| 20”x18.75”x13.5”| 20”x34.5”x14.5”
68 lbs.| 57 lbs.| 84 lbs.
Ampeg reserves the right to change specifications without notice.
Ampeg is proudly Made in America. ©1999 SLM Electronics, 1400 Ferguson Avenue,
St. Louis, MO 63133 U.S.A.
P/N 47-588-03 • 10/99