Dan D'Agostino Relentless Mono Amplifier User manual

OWNER’S MANUAL
RELENTLESS
MONOBLOCK
AMPLIFIER

Every audio designer has a product they’ve always wanted to make but never could.
Either they worry it would be too costly for their customers to accept, or they fear it
would be too far ahead of its time, or they lack the resources to fund the research and
development process. But thanks to the incredible support and encouragement that our
customers and dealers have given me since our founding days, I finally felt I could build
the amplifier I always dreamed of making: the Relentless monoblock.
The Relentless monoblock is the product of a simple question: “What amplifier would
I build if I could build any amplifier I wanted?” The simple answer is: an amplifier without
any limits.
Of course, every amplifier has at least one limit: the amount of power it can pull from
a household AC circuit. But the Relentless is designed to work not only with standard
110-volt AC, but also with 220-volt/30-amp circuits, which allows it to deliver a staggering
6,000 watts of continuous power into 2 ohms. With the Relentless, every speaker ever
made can achieve its best possible performance.
I designed every stage of the Relentless from scratch. The unique input stage achieves
extraordinarily low noise and distortion by assuring that the positive and negative halves
of the signal are perfect opposites of each other, even if the incoming signal is not
perfectly balanced. The gain stage operates in the current domain instead of the voltage
domain, so it cannot be affected by fluctuations in the speaker’s impedance. My Super
Rail design provides additional voltage to the gain stage, effectively “turbocharging” the
output stage to deliver even greater dynamics and maintain an even firmer grip on the
speaker. The linear open-loop response of these stages allowed me to eliminate global
feedback, and thus preserve the music’s subtlest details.
I couldn’t have built the Relentless if I weren’t confident that my customers and dealers
would back me in my efforts to create the world’s best audio components, bar none.
I thank you for purchasing this amplifier… and for believing in my vision.
Sincerely,
Founder, CEO, and chief designer of Dan D’Agostino Master Audio Systems
A NOTE FROM DAN D’AGOSTINO

Dan D’Agostino Master Audio Systems is a registered trademark of Dan D’Agostino Master Audio
Systems LLC. The information in this owner’s manual is subject to change without notice. Current
Version 1.0 of this manual was produced by the Dan D’Agostino Master Audio Systems LLC
engineering, sales and marketing departments.
The information in this manual is the sole property of Dan D’Agostino Master Audio Systems LLC.
Any reproduction in whole or part without the expressed written permission of Dan D’Agostino Master
Audio Systems LLC is prohibited. No material herein may be transmitted in any way, including either
electronic or mechanical methods, for any purpose without the expressed written permission of
Dan D’Agostino Master Audio Systems LLC.
WARNING
Do not expose this amplifier to moisture or excessive humidity, and do not use it outdoors. Fire hazard
may result.
The lightning flash with arrowhead, within an equilateral triangle, is intended to alert the
user to the presence of uninsulated “dangerous voltage” within the product’s enclosure
that may be of sufficient magnitude to constitute a risk of electrical shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the
presence of important operating maintenance (servicing) instructions in the literature
accompanying the appliance.
CAUTION
No user-serviceable parts inside. Do not open the amplifier’s chassis or remove any of its screws.
Contact Dan D’Agostino Master Audio Systems LLC or your dealer if you have service needs.
LEGAL NOTIFICATIONS
Package contents
If any of the following items are missing, please contact your dealer:
1 Relentless monoblock amplifier encased in protective vinyl sleeve
1 owner’s manual
4 pair of white lifting gloves
1 microfiber cleaning cloth
1 AC power cord (selected for your voltage and socket requirements)
1 ratchet with custom carbon-fiber socket for binding post
Unpacking the Relentless monoblock amplifier from its case
Each Relentless amplifier weighs 570 lbs/258 kg, so it requires at least four strong adults to lift. Be sure
to have a place cleared for it before you lift, and move the box as close as possible to the spot where
the amplifier will rest.
Installation requirements
In most cases, the Relentless amplifiers will have to sit directly on the floor, because few shelves or
stands can support their weight. If you do use a stand, make sure it has been designed specifically to
support the Relentless amplifier. Stands used for other amplifiers will not be strong enough.
Adequate ventilation must be provided for the amplifier. There should be at least 6 inches of
clearance on each side of the amplifier and 6 inches of clearance at the top, and the bottom vents
of the amplifier must not be obstructed by thick carpet, dust, etc. The amplifier may be installed in
a closed cabinet in an equipment closet, but the cabinet or closet must be designed with substantial
ventilation at top and bottom; active ventilation (i.e., powered fans) is preferred. Do not place the
amplifier directly on a carpeted floor.
For best possible sound quality and maximum output, you must connect each Relentless monoblock
amplifier to at least a dedicated 20-amp outlet. If your speakers are rated at 4 or 2 ohms impedance,
and you want the amplifier to be able to achieve its maximum rated power, you will have to have two
220-volt/30-amp sockets installed, one for each amplifier. This is the same type of outlet commonly
used to power electric clothes dryers and ovens, and any licensed electrician can install them.
UNPACKING AND INSTALLATION

Speaker cables
Install the speaker cables first. We recommend the use of high-quality cables terminated with spade or
ring lugs that will fit the amplifier’s binding posts. We advise against the use of bare-wire connections.
Note that the positive (+) binding post has a red ring and the negative (-) binding post has a black ring.
Double-check to confirm that you are connecting your speaker cable’s conductors to the appropriate
binding posts—red to positive, black to negative. If your cables are marked to show desired signal flow,
orient the cable so that the installation conforms to the cable manufacturer’s instructions.
Carefully loosen each speaker binding post to install speaker cables tipped with spade lugs or rings.
Turn counter-clockwise to loosen. If using spade lugs, insert each spade lug so that its two tines
straddle the binding post, then tighten the binding post nut with a binding post wrench. If using rings,
remove the binding post nut entirely, place the ring on the binding post, then replace the nut and
tighten it securely.
A firm connection, tight enough that the spade lug or ring cannot move, is all that’s needed. Do not
use a conventional wrench to tighten the binding posts. Be sure the wires are not in contact with
one another.
Interconnect cables
Connect the XLR cable to the input by pushing the cable onto the jack. To release the XLR cable, push
on the small tab on the end of the jack then grasp the cable by the plug and gently pull it out. Never
grasp interconnect cables by the cable itself—you could damage the cable.
12-volt trigger input and output
The 1/8-inch (3.5mm) 12-volt trigger input and output jacks allow the Relentless to turn on automatically
when connected to a preamp or home automation system with 12-volt trigger output. Connect a
cable with a 1/8-inch plug (stereo or mono) on each end from the preamp’s 12-volt trigger output
to the amplifier’s 12-volt trigger input, and a second cable of the same type from the amp’s 12-volt
trigger output to the other amplifier’s 12-volt trigger input. The amplifiers will automatically power up
whenever the preamp is powered up.
MAKING CONNECTIONS TO THE
RELENTLESS MONOBLOCK AMPLIFIER
1. Heat sink venturis
2. Top panel vents
3. Power meter
4. Standby/power button
5. XLR audio input
6. 12-volt on/off trigger input
7. 12-volt trigger output
8. Three-position toggle switch for
power meter brightness
9. Speaker cable binding posts
10. Main power switch
11. AC power cord terminals
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AC cord
The Relentless amplifier is fitted with threaded terminals for its power connections, rather than the
IEC connector found on almost all other power amplifiers. Your amplifier has been shipped with
the appropriate power cord for the voltage and socket available in your region/country. We strongly
recommend you have a licensed electrician connect your power cable, to ensure the connections are
correct. Incorrect power connections will void your warranty and can damage your amplifier.
To connect the power cable, remove the two screws on the plastic cover that protects the AC cable
terminal connections. Remove the nut on the amp’s positive terminal, place the spade ring of the
positive (+) conductor of the cable over the terminal, then replace the nut. Tighten the nut firmly but
gently with a 3/4-inch socket wrench. Use of excessive force on the socket wrench could damage the
terminal. Repeat the process for the negative (-) and ground conductors, then replace the plastic cover
and tighten the two screws down to secure it.

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Item Part Number Description Revision Qty
1 32217-01 Meter Bezel 8 1
2 32217-02 Meter Housing 7 1
3 32217-03 Meter Plate 10 1
4 32217-04 Meter Blind 7 1
5 32217-05 Faceplate 9 1
6 32217-06 Rear Panel 14 1
7 32217-07 Bottom Plate 9 1
8 32217-08 Top Cover 7 1
9 32217-09 Hump 6 3
10 32217-10 Device Bar, Left 12 1
11 32217-11 Heatsink, Right & Left 7 2
12 32217-12 Device Bar, Right 11 1
14 32217-14 Capacitor Mtg Plate 9 1
15 32217-15 Capacitor Standoff 6 2
16 32217-16 Bus Bar, Single 9 2
17 32217-17 Bus Bar, Double 10 1
20 32217-20 Power Supply Mtg Plate 8 1
23 32217-23 Perf Insert 8 2
24 32217-24 Foot - Cone 6 4
26 32217-26 Top Cover Ret. Washer 1 2
27 32217-27 Button 3 1
28 32217-28 Binding Post Insulator 1 4
29 32217-29 Binding Post Nut 3 4
30 32217-30 Binding Post Washer 2 6
31 32217-31 Binding Post 5 2
33 32217-33 Binding Post Acorn Nut 1 2
34 32217-34 Binding Post Washer, Lg 1 2
35 32217-35 Grounding Post 3 1
36 32217-36 Rear Power Box 2 1
50 EPC-017 on_off 1.08.18 1
51 EPC-031 mono switch 1.08.18 1
52 EPC-104 Power Supply 1
53 EPC-131 Relentless Rectifier 1.08.18 1
54 EPC-117 Modular Output Board 1.08.18 6
55 EPC-117 Modular Output Board 1.08.18 with Cable Connector 2
56 EPC-121 Input Board 1.08.18 1
57 EPC-130 Power Relay 1.08.18 1
58 EPC-132 Speaker Relay Board 1.08.18 2
59 EPC-133 Voltage Select 1.08.18 1
60 C4-104080-7 Transformer Housing, Sm 1
61 MTP-281 Transformer Housing, Lg 1
62 meter glass 1
63 switch 1
64 power post 3
65 high speed rectifier mounting pad 4
66 capacitor 6
67 NC3FD-V XLR Connector 1
70 91075A440 6-32 x 1/4"L M/F Standoff 7
71 92196A556 1/4-20 x 3 1/2"L SHCS 2
72 92200A550 1/4-20 x 2"L SHCS 6
73 92200A344 10-32 x 5/8"L SHCS 26
74 92200A347 10-32 x 1"L SHCS 7
75 92200A542 1/4-20 x 1"L SHCS 14
76 91075A430 4-40 x 1/4"L M/F Standoff 20
77 92949A108 * 4-40 x 3/8"L BHCS 208
78 92949A105 4-40 x 3/16"L BHCS 22
79 92949A146 6-32 x 3/8"L BHCS 5
80 92200A345 10-32 x 3/4"L SHCS 9
81 92949A141 6-32 x 1/8"L BHCS 7
82 92949A537 1/4-20 x 1/2"L BHCS 4
83 92949A194 8-32 x 1/2"L BHCS 4
84 92210A144 6-32 x 1/4"L FHCS 2
85 91771A108 4-40 x 3/8"L FHPh 4
86 92210A537 1/4-20 x 1/2"L FHCS 2
87 92196A113 4-40 x 3/4"L SHCS 8
88 92200A110 4-40 x 1/2"L SHCS 12
89 92196A278 10-32 x 1 3/4"L SHCS 6
90 92196A541 1/4-20 x 7/8"L SHCS 3
91 92196A569 1/4-20 x 7.0"L SHCS 2
92 92196A539 1/4-20 x 5/8"L SHCS 1
93 92311A542 1/4-20 x 1.0"L Set Screw 1
94 92210A153 6-32 x ?"L FHCS 2
95 90089A335 .015 thick Fiber Washer 1
96 9452K362 Rubber O-ring 2
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A LOOK INSIDE
Premium parts and precision
machining of copper and
aluminum are fundamental in
achieving the uncompromising
performance and build quality
of the Relentless monoblock
amplifier. The Relentless is
designed, fabricated and
assembled by hand using
USA machinists, vendors
and parts procurement.

Initial power-up of the amplifier
Make sure the main power switch on the back of the amplifier is in the up position. The power meter
will be illuminated in red. The standby/power button is located on the front underside edge of the
amplifier, right of the meter. Pressing the button will power up the amplifier, and the power meter
will change to green. After power is switched on, the Relentless amplifier requires approximately
30 minutes to reach optimal operating temperature. Although the amplifier will sound excellent upon
initial listening, the sound quality will improve as it warms up, much as the flavor of a fine red wine
improves if it is allowed to breathe for a few minutes.
During operation
The Relentless amplifier requires no adjustments during normal operation. If there is no sound or the
sound quality is in some way impaired, consult the “Troubleshooting” section in this manual.
Power meter setting
The Display Low/Off/Hi switch on the back of the amplifier adjusts the illumination of the meter.
Move it to the left (when looking at the amp from the rear) for low brightness and to the right for high
brightness. If the switch is in the center position, the meter light will be turned off. The Relentless
amplifier’s power meter has self-adjusting sensitivity, so it will automatically provide a setting that
delivers the most useful response for any given power level.
Maintenance
The Relentless amplifier requires no user maintenance other than to keep it clean and ensure that the
vents remain unobstructed.
To clean the amplifier, first disconnect the AC plug. Spray a small amount of distilled water onto the
supplied microfiber cloth and gently wipe the amplifier’s surface. Do not apply the water directly onto
the amplifier.
OPERATION
TROUBLESHOOTING
If you experience any issues with the operation of your Relentless monoblock amplifier,
please contact your dealer or Dan D’Agostino Master Audio Systems at [e-mail]
or 480.575.3069.
RELENTLESS MONOBLOCK AMPLIFIER
LIMITED WARRANTY
Dan D’Agostino Master Audio Systems LLC warrants the Relentless monoblock amplifier against
manufacturing defects and defects in materials for five years from the date of purchase from an
authorized Dan D’Agostino Master Audio Systems dealer, subject to the conditions listed below:
1. The warranty covers only new products purchased from an authorized Dan D’Agostino
Master Audio Systems LLC dealer.
2. The warranty is non-transferable and is valid only for the original purchaser.
3. The warranty is valid only if the product has been used according to the instructions in
the owner’s manual. Damage due to accidents or owner abuse or neglect is not covered
under this warranty.
4. All service must be performed by an authorized Dan D’Agostino Master Audio Systems
dealer. Damage resulting from service by other parties is not covered under this warranty.
5. All products returned for service must be packaged in the original container and must
include a photocopy of the original purchase receipt. If the original container has been lost
or discarded, contact Dan D’Agostino Master Audio Systems LLC for a replacement.
6. If the product must be shipped back to Dan D’Agostino Master Audio Systems LLC for
warranty service, the customer shall pay shipping costs. Dan D’Agostino Master Audio
Systems LLC will pay for return shipping.
7. Before shipping the product to Dan D’Agostino Master Audio Systems LLC for service,
the customer must first obtain a Return Authorization (RA) number by calling Dan
D’Agostino Master Audio Systems LLC. The RA number must be marked clearly on the
side of the package.
8. This warranty covers only defects in products made by Dan D’Agostino Master Audio
Systems LLC. It does not cover incidental or consequential damages, or damages to other
products resulting from defects in Dan D’Agostino Master Audio Systems LLC products.
9. U.S. residents: Depending on which state you live in, you may have other rights not
elaborated in this document. For further information, contact Dan D’Agostino Master
Audio Systems LLC.
10. Residents of other countries: Your authorized importer or dealer bears the direct
responsibility for warranty coverage of your amplifier. Please contact your importer
or dealer with requests for service under warranty. Dan D’Agostino Master Audio
Systems LLC will work with your importer or dealer to assure that the terms of the
warranty are fulfilled.

SPECIFICATIONS
Frequency response 20 Hz to 20 kHz, ±0 dB
<0.1 Hz to 100 kHz, +0/-3 dB
Signal-to-noise ratio >113 dB, wideband, unweighted,
ref. to full power output
Gain 28 dB
Total harmonic distortion <0.007% at 1 kHz, at 1,500 W, 8Ω
Input impedance 100 kΩ
Output power 1,500 W RMS at 8Ω
3,000 W RMS at 4Ω
6,000 W RMS at 2Ω
Output voltage 320 V peak to peak
113 V RMS
Output current 400 A peak
Slew rate 100 V/μs
Output impedance <0.03Ω, 20 Hz to 20 kHz
Damping factor >267, 20 Hz to 20 kHz, ref. to 8Ω
Power consumption Standby: 40 W
Idle: 480 W
Maximum: 10 kW
Input 1 balanced via XLR connector
Outputs 1 pair binding posts
Dimensions 22.5 x 11.5 x 32.5 in (whd)
57.2 x 28.0 x 82.6 cm (whd)
Weight (approx.) 570 lbs / 258 kg

www.dandagostino.com
© 2018 DAN D’AGOSTINO MASTER AUDIO SYSTEMS LLC. ALL RIGHTS RESERVED.
Designed, handmade and assembled in the USA using
USA machinists, vendors and parts procurement.