Owners Manual For The
Powerbloc
Series Amplifiers
1
Table of Contents
Page
Registration
Owners Record 3
Warranty 4
Safety 5
Care 6
Setup
Connections 7-9
Powering Up 9
Troubleshooting 10
Technology
An Engineer's Perspective 11-12
2
Designer Notes 13-14
Specifications 15-16
Owners Record
Date of purchase: ___________________
Model: Powerbloc
Please Choose: Mono, 2 or 4
Serial No: _________________________
3
The serial number is located on the rear of the unit. Record this
number in the space provided below. Refer to this when calling your
dealer regarding this product.
Register your product at www.legacyaudio.com/register
Thank you for listening with Legacy Audio. These hand-crafted
instruments will provide you with many years of listening enjoyment.
Share your Legacy speakers/electronics with the Legacy
community. Post your Legacy experience and system photos at
facebook.com/legacyaudio . Like the page to receive the latest
Legacy announcements.
• The warranty applies to the original owner and is not transferable.
• The warranty applies to products purchased from an “Authorized Legacy Dealer”.
• The warranty on dealer stock will extend for a maximum of two years from invoice.
The warranty does not cover transportation costs of product to or from the customer, distributor or
dealer, or related shipping damage.
Exclusions from Warranty
The following situations or conditions are not covered by the Legacy Audio warranty:
• Accidental damage, electrical abuse or associated equipment failure.
• Use inconsistent with recommended operating instructions and specifications
• Damage caused by modification or unauthorized service
• Costs associated with the removal and reinstallation of defective products. Consequential damage to
other products.
• Normal wear such as fading of finishes due to sunlight.
Warranty
• The warranty on active components such as digital processors or amplifiers is three (3) years
Legacy Audio supports its customers and products with pride. We cheerfully warrant our amplifiers
from defects in materials and workmanship for a period of seven (3) years. Please register your
product with Legacy Audio. Should you require service Legacy will require a proof of purchase in
order to honor the warranty - so please keep your receipt.
4
Do not block any ventilation openings.
Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus
that produce heat.
The power cable should be unplugged from the outlet during severe electrical storms, or when
unused for a long period of time.
Grounding: Adequate precautions should be taken so that the grounding provisions built into an
electrical product are never defeated.
Safety
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO
NOT USE THE AMPLIFIER NEAR WATER OR IN WET LOCATIONS, DO NOT EXPOSE IT TO
RAIN OR MOISTURE, DO NOT EXPOSE IT TO DRIPPING OR SPLASHING FROM OTHER
SOURCES, AND ENSURE THAT NO OBJECTS FILLED WITH LIQUIDS (SUCH AS VASES)
ARE PLACED ON IT. DOING SO MAY RESULT IN DAMAGE TO THE UNIT AND THE RISK
OF ELECTRIC SHOCK, WHICH MAY RESULT IN BODILY INJURY OR DEATH.
WARNING: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE THE COVER.
NO USER-SERVICEABLE PARTS INSIDE.
5
Care
If you wish to clean your amplifier, use a diluted ammonia based window cleaner. Do not use any
abrasive cleaners or chemical solvents. Take care not to damage the aluminum faceplate, since
aluminum is a medium hardness metal and can be scratched by the careless use of tools during
the installation. Save your box and packing material; they may be necessary for moving or
shipping the unit.
6
Connections
To Right Speaker
To Left Speaker
Included IEC power
cable connection
Unbalanced or balanced
connections from preamp or
DAC with volume control
Be certain all associated equipment is turned off before making any connections. Position your
amplifier as near the final location as possible while leaving sufficient access to its rear panel
connectors. To provide for adequate ventilation you should allow at least a couple of inches on
each side of the amplifier. Check that the amplifier is turned off. Insert the power cord into the AC
LINE INPUT on the back panel and then connect it to an appropriate power source.
12V trigger connection
Master Power
Switch
Powerbloc2
7
Connections
12V trigger connection
Unbalanced or balanced
connections from preamp or
DAC with volume control
Included IEC power
cable connection
Speakers 1 , 2 , 3 , 4
To Positive Binding Post
Speakers 1 , 2 , 3 , 4
To Negative Binding Post
Master Power Switch
Powerbloc4
8
Powering Up
Connections
The Powerbloc Series of amplifiers uses a universal power supply. The included IEC power cable or any other IEC
standardized cable can be utilized.
The 12V trigger allows your Powerbloc to interface with the rest of your system. The trigger can receive signals from
your receiver, preamplifier or other gear, to toggle the Powerbloc power off and on with the rest of your system.
Recommended power up sequence is source followed by preamp/processor, then your amplifier. Powering down
should be done in reverse order.
Switch toggled right = always on
Switch toggled left = triggered on/off
Make sure the master power switch at the back of the unit is on by pressing down on the (I). When the (0) is
pressed down, the master power switch is off.
The control switch is located under the display window on the front panel. When the control switch is toggled
to the left, triggered on/off is engaged so the power amp will power on when it receives a signal from the
optional 12V trigger. When the power switch is toggled to the right, the power amp is always on.
9
Symptom
Probable Cause
Solution
No power
Front panel not
illuminated
Power cord is disconnected
Front panel switch toggled to left
position, no 12VDC input
AC fuse is blown
Connect power cord, verify at power strip
Set rear panel switch to on 'I' position
Connect 12 VDC input from source
If not using trigger, toggle front panel switch to right ON
position
Replace rear panel fuse with same rating.
Amplifier won't
trigger on or off
DC trigger source wored in
reverse or voltage too low
Test with 9 Volt batter
Front panel switch toggled to right
position
Toggle to left for triggered control
Power on, but no
sound
Bad connection from preamplifier
or controller
Check input connection or try a different cable or a different
speaker
Over-current protection circuitry
has been activated
Check speaker load impedance. Check speaker wires and
connections. Unplug amplifier for 30 seconds to reset
No signal present
Play CD or other source verifying input selector on preamp.
Streaming is less reliable for this test.
No sound from one
or two channels
Distorted sound
Internal fuse blown on channels'
supply
Internal fuse is degraded
Shorting of output
Rubbing speaker voice-coil
Intermittent contact
Contact Legacy Audio at 800-283-4644
Check speaker cable connections
Verify by driving speaker with different channel
Hum heard from
speakers
Problem with preamplifier or
source component
Disconnect inputs to amplifier with power off, then power on to
verify
Ground loop
Be sure amp is on same power circuit. Isolate with Ebtech
HumX or other ground lifter
Ground loop from cable TV
Install cable isolation device such as the Xantech 634 Ground
Breaker. Refer to www.xantech.com
Top cover feels
unusually warm
Inadequate ventilation
Allow 2" of open space above amplifier. Do not stack without
forced air cirulation
Rear panel power switch set to off
'0' position
Troubleshooting
10
An Engineers Perspective: by Legacy Chief Bill Dudleston
What prompted you to return to amplifier manufacturing?
We never really stopped. Besides the amplifiers built for us by CODA, we assembled our own amps for
professional speakers and subwoofers for years. In 1998 we licensed high efficiency circuitry from LGT with
conventional power supplies and massive transformers. We experimented with a vast range of designs for another
10 years before working with the early ICEpower designs. When you design with DSP, it is advantageous to
provide powered channels and ICEpower had the first good sounding wide bandwidth units that offered high
reliability.
Why did you choose ICEpower?
I should provide some history:
Nearly twenty years ago Karsten Nielson defended his PHD thesis to Malcom Hawksford on a new type of Class D
amplifier design. At this time most class D amps were limited bandwidth (used in subs mostly). B&O hired Nielsen
to run an 8 person R&D facility in Denmark to set new standards for Class D amps.
In 2001 the ‘A’ series amps brought high efficiency but limited sustained current. 2005 brought the 200ASC amps
which caught the eye of audiophile designers like Jeff Roland. These modules had excellent sonic qualities but did
not boast higher current supplies as built.
In 2014 ICEpower released the amplifier that I had been waiting for. This unit met their original design goals:
distortion of 0.006%, bandwidth from 1Hz to 100kHz, the lowest of noise levels, no transformer hum, 83%
efficiency and 30amps of peak current. This amp is the 700ASC and it has the industry’s highest reliability thanks
to an amazing regimen of tests (like 70g/12ms of acceleration applied in 6 directions, short circuit protection, RFI
rejection, etc). Presently 80% of ICEpower’s 50 employees are directly involved in research. The folks at
ICEpower make up one of the most focused design groups that I have encountered.
Regarding the Powerbloc2 and Powerbloc4 Amplifiers, are they identical in build, excepting the number of channels?
Nearly. Both have dual 30 amp peak power supplies. However the Powerbloc4 shares a supply with two channels,
whereas the Powerbloc2 dedicates a separate supply to each channel, thus providing greater output into
impedances below 4 ohms. Circuit path is otherwise the same.
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Have you looked at other designs?
An Engineers Perspective: by Legacy Chief Bill Dudleston
12
Most definitely. The power on demand concept is not new. You might recall Carver’s Magnetic Field design and
Soundcraftsman’s Phase Control Regulation, and some variations on Class H designs as much as 40 years ago.
The power supplies were pretty soft and none of them sustained current for extended periods despite their clever
designs at the time. Early Pulse Width Modulated designs (Class D) weren’t considered high performance yet with
their lower damping factor, impedance dependency, R.F. emissions, output filtering requirements, and slower
switching rate. Now we have ICEpower, Hypex, Pascal, Abletech, Tripath’s class T, BASH, etc., each with their
variations on pulse width modulated designs. All of these designs had to address these 4 problems one way or
another. I have tested all of these amps in my lab for extended periods. Tripath and Abletech are particularly cost
efficient, and BASH is a hybrid of a Class D and Class AB design. ICEpower, Pascal and Hypex are well
established in the pro world for durability and huge dynamics.
Even with the sophistication of these modern designs owing largely to semiconductor development, adequate
execution is paramount for reliability. The failure rate on the subwoofer modules industry wide was pretty atrocious
over the past decade as speaker manufacturers were looking for the greatest output/cost.
In the end the units with the highest quality capacitors, adequate heat sinking for the transistors, and ample
transistor capability make for a lasting design and consistently clean, powerful sound.
We chose the ASC 700 modules for these very reasons. Extremely durable and very capable in to our high power
handling loudspeakers, most of which are 4 ohm. These amps are built to last.
To the listener what ultimately matters is the sound. We found this amplifier can hold its own with the best
amplifiers today. We install up to four of these units into the flagship DSP controlled Legacy V speaker system.
That’s the strongest endorsement I can give it.
ICEpower Features
Universal Mains SMPS (85 - 264VAC, 47Hz - 63Hz)
Balanced inputs and outputs
Comprehensive protection scheme (thermal, over-current, high-frequency, under-voltage)
Mechanically rugged construction (Tested for 70G shocks in six directions)
Pre-approved for Safety, EMC and RoHS compliance
Designer Notes
Intelligent Switch-mode Power Supply with superior control of the amplifier section.
Proprietary chip design assures smoother interaction.
Controlled Oscillating Modulator provides a self-oscillation closed loop system that
suppresses non-linearities in the output stage delivering a very high power supply rejection ratio.
The ICEpower’s 60 dB PSRR compares to the 0 dB in a basic Class D design, while both
modulation and regulation are accomplished in the same block.
Multivariable Enhanced Cascade Control applies a secondary feedback loop after the output
filter, compensating the non-linearities of the output filter itself while the inner loop compensates
the modulator and power stage.
The Powerbloc series amplifiers utilize three of the most important advances in modern amplifier
design. Among the qualities of these technologies, feedback is delivered directly at the output of
the amplifier to provide very low output impedance, resulting in a much higher damping factor for
precise bass control superior to most Class AB designs. The result is a stable, efficient,
wide-bandwidth amplifier with effortless dynamics.
13
Designer Notes
14
Inputs: 2 balanced XLR, 2 unbalanced RCA
Outputs: 2 pair gold plated safety approved five-way binding posts
Damping factor: 1,000< 1kHz
Voltage Gain: 27.4 dB
Dynamic Range: 117 dB
THD: 0.005% at rated output
TIM: 0.0045% at rated output
Dimensions: 3" H x 17" W x 14" D
Unit Weight: 13 lbs
Shipping Dimensions: 7.5" H x 21.75" W x 16" D
Shipping Weight: 17 lbs
Power Output: 325 watts per channel x 2 @ 8 ohms, 650 watts per channel x 2 @ 4 ohms
Specifications for Powerbloc2
Peak Current: 30 amps/channel
15
Damping factor: 1,000< 1kHz
Voltage Gain: 27.4 dB
Dynamic Range: 117 dB
THD: 0.005% at rated output
TIM: 0.0045% at rated output
Dimensions: 3" H x 17" W x 14" D
Unit Weight: 13 lbs
Shipping Dimensions: 7.5" H x 21.75" W x 16" D
Shipping Weight: 17 lbs
Specifications for Powerbloc4
Power Output: 325 watts per channel x 4 @ 8 ohms, 650 watts per channel x 4 @ 4 ohms
Inputs: 4 balanced XLR, 4 unbalanced RCA
Outputs: 4 pair gold plated safety approved five-way binding posts
Peak Current: 30 amps shared channels 1,2 and 30 amps shared channels 3,4
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Legacy Audio
3023 E. Sangamon Ave.
Springfield, IL 62702 USA
800-283-4644
States that this product is in conformity with the
with the essential requirements and other relevant
provisions of:
Low Voltage Directive 2006/95/EC
EMC Directive 2004/108/EC
CE Declaration of Conformity
WEEE Compliance
Product Disposal—
Certain international, national
and/or local laws and/or
regulations may apply regarding
the disposal of this product. For
further detailed information,
please contact the retailer where
you purchased this product or
the Legacy Audio Distributor in
your country. A listing of Legacy
Audio Distributors can be found
on the Legacy Audio website
www.legacyaudio.com
or by contacting Legacy Audio
at: 3023 E. Sangamon Ave.,
Springfield, IL 62702,
USA—Phone: +1 217 544-3178.
All information contained in this manual is
accurate to the best of our knowledge at the time
of publication. In keeping with our policy of
ongoing product improvement, we reserve the
right to make changes to the design and features
of our products without prior notice.
17
Notes:
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©2017 Legacy Audio
3023 E Sangamon Ave.
Springfield, IL 62702
Phone: 800-283-4644
Fax: 217-544-1483
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