Aguilar DB 751 User manual

Model DB 751
Hybrid Bass Head
The DB 751 Bass Head features a combination of raw power and rich tone that
continues the legacy of the DB 750. The DB 751 is a groundbreaking hybrid with
a discrete Mosfet output section and a 3-tube preamp. While maintaining the
legendary sound of the DB 750, the DB 751 features improvements in the EQ
section, a better control layout, detachable rack ears, and thermally controlled
fans. This amp has the headroom to bring your tone to life no matter what kind of
music you are playing. For sound clips and sample settings be sure to visit our
website at:www.aguilaramp.com.
Aguilar Amplification LLC
New York City
www.aguilaramp.com

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Specifications:
Power Output: 975 watts @ 2 ohms, 750 watts @ 4 ohms, 400 watts @ 8 ohms
Preamp Section: Three 12AX7s
Power Section: 12 complimentary lateral MOSFETs
Transformer: Custom Aguilar toroidal power transformer.
EQ Section: passive tone stack with active midrange element, bass: +12 / -12 @
40Hz; midrange: +12 / -12 @ 750Hz; treb: +12 / -7 @ 4kHz
Deep Switch: Adds 5 dB of broad-band boost at 30 Hz
Bright Switch: Adds 5 dB of broadband boost at 5-7 kHz
Effects Loop: Send is push/pull for line or instrument level; Return is push/pull
for parallel or series operation
Inputs: One 1/4" input jack with an active/passive switch
Outputs: Two Neutrik Speakon speaker outputs, Jensen XLR balanced
output (-32dB) with a pre/post EQ switch and a ground lift switch.
Tuner out.
Cooling: High quality whisper fans with thermal speed control
Dimensions: 17" W x 14" D x 5.25" H
Rack Size: Three Spaces, Includes detachable rack ears
Weight: 42 lbs
Warranty: Ten Year Limited
Optional: Footswitch, Tolex Head cases in DB series colors, Rack bag

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Front Panel Features:
Input:
-6 dB Switch:
Inserts a –6dB pad in the signal path to allow flexibility when adjusting the gain for a
bass with very high output
Gain Knob:
Controls the gain of the preamp section
Bright Switch:
Adds 5dB of broadband boost at 5-7 kHz
Treble Knob:
+12 / -7 dB @ 4 kHz.
Midrange Knob:
+12 / -12 @ 750Hz
Bass Knob:
+12 / -12 @ 40 Hz
Deep Switch:
Adds 5dB of broadband boost at 30 Hz
Master Knob:
Controls volume
Clip Light:
Flashes if the preamp is clipping. Turn down either the “Gain”, the EQ, or “Master”
volume.

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FX Send:
Sends the signal to your effects units. Connect the input of your effects unit to this jack
FX Return:
Returns the signal from your effects units to the amplifier.
Connect the output of your effects unit to this jack.
Effects Loop:
The “Send” knob is push/pull for selecting line or instrument level. This allows you to
use a studio effects unit (line level) or a stomp box (requires instrument level) in the FX
loop. Adjust the amount of “Send” so as to get maximum performance from your effects
unit and the “Return” to get the right amount of effected signal.
The “Return” knob is push/pull for parallel or series operation. In parallel mode, the
effected signal is mixed to the dry sound. In series mode, the effects in the loop will
process the entire signal. The amount of effects can be adjusted with the return knob. If
you pull the return knob out for series operation without any effects plugged in the loop,
the loop will be open and no sound will result.
XLR Balanced Output:
Use the Pre-EQ setting in a concert situation where the sound engineer is taking a signal
into the house-mixing console. The engineer is now getting their feed before the preamp
stage, which allows them to use appropriate EQ for the venue. The EQ on stage will still
be controlled by your settings. If the engineer wants your EQ settings included in the
mix, set the control to Post EQ and your settings on stage will be sent to the house.
The D.I. output is –32dB. This level is the correct output for a signal going into the
preamp on a mixer. Our balanced output uses the highest quality Jensen output
transformer. If you hear any ground noise, change the position of the ground lift switch
under the output
Footswitch:
Use the optional Aguilar footswitch to mute the signal for silent tuning.

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Rear Panel:
Speaker Outputs:
Two Neutrik Speakon connectors are provided. Use 12 gauge or larger speaker cable for
proper connections.
Tuner out:
This output sends the signal to your connected tuner. This output will still be active
when you mute the DB 751.
Aguilar DB751
Diagnostic and Protection
The DB751 is equipped with a self-diagnostic and status/protection circuit. Upon power-
up, the unit’s blue status LED will blink for approximately 45 seconds. During this time
several circuit parameters are verified, or allowed to become self calibrated.
1. The high B+ voltage to the preamp tubes is slowly ramped up, allowing the tube
heaters to warm up before full current is drawn by the valves.
2. DC offset at the amp’s output is monitored. Only if none is present (normal condition),
will the unit proceed with the self-check protocol.
3. Temperature on the MOSFET heat sink is checked, and again only if normal
temperature is detected, will the status check continue.
4. If all the voltages, offsets, and temperature are in accordance with factory
specifications, then the amp’s input, and output relays will be energized. This will then
cause the operate LED to illuminate and the status LED to stop blinking. The amp is now
ready for normal operation.
5. The circuit continues monitoring the above parameters to protect both the DB 751 and
the speakers connected to the amp in the event of unit or user error. This will be indicated
by the status LED’s blinking.

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6. If the status LED continues blinking, or starts blinking during amplifier use, this
indicates a system fault. The amplifier requires servicing in order for normal operation to
resume.
Limited Warranty
Aguilar Amplification’s DB 751 hybrid bass amp is warranted to the original owner for a
period of ten years from the date of purchase against defects in materials and
workmanship. * Tubes are covered by the warranty for a period of 90 days. Abuse,
negligence, and normal wear and tear are not covered by the terms of this warranty.
The warranty period starts from the date of purchase from an authorized Aguilar dealer.
Please register your DB 751 for warranty by going to www.aguilaramp.com and selecting
“Online Registration” from the Support menu. It is important to save your original sales
receipt. You will be asked to send a copy with your amplifier.
Before sending your unit to Aguilar for repair, you must receive a return authorization
number from us. Contact us via phone, fax, or email ([email protected]) with
a description of the problem. We will then issue to you a return authorization number.
You are responsible for all shipping charges. You must ship the unit to us freight prepaid.
We will return the unit to you freight collect. For safe shipment, the product should be
shipped in its original packaging. If you no longer have this, we can arrange to sell you
replacement-packing materials.
Aguilar Amplification LLC is not responsible for shipping damage, either to or from our
service center. Claims must be filed with the carrier.
The only company authorized to perform work under this warranty is Aguilar
Amplification LLC of New York, NY.
*If you purchased your DB 751 outside the USA, please contact your local Dealer or
Distributor for your country’s specific warranty period and repair procedure.