Peavey DPC 1400X Installation guide

68 BASS PLAYER ?OCTOBER 2000
Soundroom
Soundroom
By Terry Buddingh
Construction: 4
Back in the ’80s Peavey began
experimenting with “switch-
mode”power-ampdesigns,which
use digital technology to supply
large amounts of power without
thehugetransformersandcapac-
itors required by conventional
amps. The flagship DPC 1400X
uses the company’s patented
phase-modulatedcircuitrytopro-
vide unprecedented power in a
single-rackspace package. Its
austere exterior is no indication
ofthesophisticateddesignwork
hidden inside.
Alargeglass-epoxyprintedcir-
cuitboard board spans the full
width of the rugged steel chassis,
housing the power supply and
extensive filtering components
required by a switch-mode amp.
AsmallerPCboardholdsanabun-
danceofICsandmodernsurface-
mount components. Silicone
adhesivesecuresthelargetoroidal
inductors,whilethesmallerinduc-
tors are soldered directly to the
board. A low-profile cooling fan
draws air through the back panel
and forces it through a channel-
shaped heatsink, exhausting it
through a front-panel vent.
Electronics: 4.5
With today’s proliferation of
5-strings and low alternate
tunings, power has never been
more important—extra power is
required to faithfully reproduce
extra-low notes. Solid-state class
AB amps have been the standard
for many years; these must use a
largepower-supplytransformerto
provide the high current needed
to run its output devices, as well
as large capacitors for current
storageandfiltering.Thisexplains
the large size and weight of high-
poweredconventionalamplifiers.
An alternative is to raise the 120-
volt, 60Hz line to a much higher
frequency.TheclassD1400Xuses
a switching power supply to run
at280kHz,where asmallertrans-
former and capacitors can do the
sameworkasclassABamps’heavy
components.
Most class D amps use pulse-
width modulation to control the
output stage. Since the output
devicesareconstantlybeingturned
on and off at different rates, the
amp’s performance is ultimately
limited by the speed, or rise time,
ofthedevicesused.Peaveyavoided
this problem by using two non-
changing pulses that vary in their
phaserelationshipratherthantheir
width. This elegant solution also
enables the DPC 1400X’s output
MOSFETstobedrivenwithasim-
pler circuit. The audio signal gets
amplified with the switching sig-
nal; then the high-frequency
switching signal gets filtered out
beforeitreachestheamp’soutput.
Theresultisunheard-ofpowerin
a smaller and lighter package.
TheDPC1400Xalsoincludes
Peavey’sDDT (DistortionDetec-
tion Technique) protection cir-
cuitry,whichcomparestheamp’s
outputwith itsinput andreduces
theinternalgainwhenclippingor
current limiting occurs. You can
defeat the DDT via a front-panel
button.
Ease of use: 5
Peaveyspecializesin user-friendly
products, and despite the DPC
1400X’ssophisticateddesign, it’s
noexception. All the controls and
Peavey DPC 1400X Power Amp
Bi-colored
STATUS LED Input sensitivity knob (31 detent positions) Bi-colored
SIGNAL level
LED
Output MODE
button DDT
DEFEAT/ENABLE
button
Each channel’s output offers a set of binding posts and a pair of 1/4" jacks. The inputs use a combo connector to accommodate balanced XLR
or 1/4" TRS plugs; they also accept 1/4" mono plugs for unbalanced operation. 1/4" THRU jacks allow easy connection of additional amplifiers.

OCTOBER 2000 ?BASS PLAYER 69
switches are on the front panel,
and the rear-panel connectors
are clearly labeled and easily
accessible.
Peavey placed all the control
functions conveniently on the
front panel. Two solid-feeling
knobsadjusteachchannel’sinput
sensitivity. The output mode and
DDTcircuitrybuttonsaretinyand
recessed to prevent accidental
switching—you need a small
pointedobject(likeapen)toalter
their settings. Front-panel LEDs
indicatetheamp’soperationaland
signal-level status.
The rear panel accepts a wide
varietyofconnectors,butNeutrik
Speakon connectors are conspic-
uously missing. Wasn’t there
enough room to include them?
Banana jacks provide a viable
high-current-handling alterna-
tive, though—important for an
amp this powerful.
Sound: 4.5
We preferred the tremendous
headroom bridged-mono mode
offers—it sounded punchier and
more focused than stereo mode,
withatighterandmorecontrolled
bottom. Its reserve power was
nearly frightening; one mistake
could spell death for speakers of
insufficientpower-handlingcapa-
bility.ADemeterVTBP-201spre-
amp emphasized the amp’s hi-fi
clarity and detail, while it repro-
duced a Modulus Quantum 5’s
lowest notes faithfully and effort-
lesslythroughanEdenD-410XLT
cab. There really is no substitute
foranoverabundanceofpower—
dynamics were effortless at high
volumes, and transients were
always crisp and snappy.
Forevenloudertests,we used
a pair of Peavey 410TXF cabs.
Thisallowedustotest the ampat
its limits—and it also let us hear
the DDT circuitry’s effects. At
high volume the DDT rounded
theleading-edgeattackandcom-
pressed the dynamic range, but
notexcessively.Somemayprefer
the smoother feel the DDT pro-
vides; however, with the protec-
tion disengaged we noticed a
more open, toothy growl, with
livelier dynamics and a more
assertive immediacy.
One quirk: The fan speed
tendstofollowyourplaying.With
no signal present it idles slowly,
but it speeds up immediately to
match the demand of even mod-
eratesignallevels,returningtoidle
the instant you stop playing. This
shouldn’t be a problem on a gig,
but in a quieter setting (like a
recordingstudio)itcouldbecome
annoying.
Value: 4.5
The Peavey DPC 1400X packs
unbelievablepowerintoanamaz-
inglyportablepackage.Becauseof
itsextra complexity, class D tech-
nologyisnotthecheapesttoman-
ufacture, but it becomes more
cost-effective as the power
increases.Ashigher-performance
output devices become available,
lookforevenmorepowerful(and
affordable) class D amps in the
future.Forthosemoreconcerned
with size and weight rather than
price alone, the DPC 1400X is
quite a buy. ?
Type: Class D stereo power amp
Made in: U.S.A.
List price: $1,400
Warranty: Five years limited
Dimensions: 19" x 1 3/4" x 161/2"
Weight: 15 lbs
RMS power:
Per channel, EIA (1kHz):
8Ω: 325 watts
4Ω: 500 watts
2Ω: 700 watts
Bridge mode:
8Ω: 1,000 watts
4Ω: 1,400 watts
THD: .1% @ 1kHz
Damping factor: >500
(4Ω; 100Hz)
Frequency response: +0.5dB/
–3dB(1watt;4Ω)3Hz–25kHz
Input sensitivity: 1.4V RMS
(+3dBV) for 4Ωrated power
Manufacturer’s address:
711 A St.
Meridian, MS 39301
[phone]
[phone] fax
www.peavey.com
TECH SPECS
Tight squeeze: Switch-mode amps use smaller power supply
components that enable the DPC 1400X to be shoehorned into a
single rackspace.
Cooling fan exhaust vent
Peavey DPC 1400X Power Amp
List Price: $1,400
SCORE 1 • 2 • 3 • 4 • 5
Construction: ■■■■■■■ ■■■■■■■
Electronics: ■■■■■■■■ ■■■■■■■■
EaseofUse: ■■■■■■■■■ ■■■■■■■■■
Sound: ■■■■■■■■ ■■■■■■■■
Value: ■■■■■■■■ ■■■■■■■■
Bottom Line: Awesome power in a
lightweight box.