QSC PL380 User manual

REPRINTED FROM JANUARY 2008 WWW.PROAUDIOREVIEW.COM
Copyright 2008 JRS Publishing (USA), Inc. Reprinted with permission.
QSC is a name that has been around for
some time now. At one point or another,
potentially everyone in the industry has
been exposed to at least one or more of the
company’s products. Now that market
penetration continues with the new
QSC PowerLight3 series amplifiers —
or, as QSC puts it, “the ultimate analog
amplifier.”
| FEATURES
The PowerLight3 upgrades the
PowerLight2 series, adding and refining
some appreciated functions. The new
PL380 ($3,599) is QSC’s flagship model,
with an output of 8,000 watts (two chan-
nels driven at 2 ohms at 4,000 watts per
channel). The PL380 is rated as a Class D
switching power supply amp. This amp
features QSC’s reactive “back EMF,”
which recycles the unused energy back to
the power supply to produce an AC effi-
ciency of up to 85 percent, keeping AC
power demand to a minimum.
The PL380’s frequency response is
rated from 20 Hz to 20 kHz ±0.2 dB.
Maximum distortion is rated at 0.20 per-
cent from 4 to 8 ohms, with noise rated at
-104 dB. Input sensitivity is adjustable
from three settings: 26 dB (5.27V), 32 dB
(2.67V), and 1.2V (39.1dB) with input
impedance set at >10k ohms. The
Damping factor at 8 ohms is rated at 200.
All of the standard input and output con-
nectors are on the amp: XLR inputs with
Neutrik and 5-way binding post outputs.
The front panel of the PL380 is common
with most other QSC amps, with attenua-
tion knobs from each channel (the stan-
dard LED “Christmas Tree” of signal). The
PL380 sits in only two rack spaces, and
weighs in at a respectable 24 pounds.
The PL380 also supports remote control
through QSC’s QSControl BASIS net-
worked audio platform and the DataPort
at the rear of the amp. The PL30 is shipped
with an 18A/30A Twist-Loc power cable
to a Neutrik Power-Con at the amp. All of
the common amplifier and load/power
protection of short circuit, open circuit,
thermal, RF and DC fault is also there,
along with on/off muting and active in-
rush limiting.
| IN USE
I had the opportunity to use the PL380
for several months. The first thing I did
after opening the box was to change out
the Twist-Loc power connector to a regu-
lar 20A Edison. This way, I could use the
amp in any situation that might pop up
(and they did pop up more frequently
than even I would have wanted).
I found the PL380 very robust in the
QSC PL380
PowerLight3 Amplifier
This analog amp offers a powerful 8,000-watt
argument as to why QSC is a go-to name in live
sound reinforcement. by David Rittenhouse
APPLICATIONS
Live reinforcement, permanent
installs
KEY FEATURES
8,000 watts (two channels driven at
2 ohms at 4,000 watts per channel);
Class D; QSC reactive “Back EMF”;
XLR inputs with Neutrik and 5-way
binding post outputs
PRICE
$3,599
CONTACT
QSC Audio | ☎800-854-4079
➲www.qscaudio.com

fact that it was lightweight, yet very pow-
erful. I was able to run it as an extra sub
amp, or as an extra amp for additional
front fills on multiple shows. I loved the
fact that QSC utilized the back panel con-
nections to work with whatever could be
thrown at them. Having both binding post
and Neutrik outputs and parallel XLR
inputs made things easier when adding it
in to existing systems, like I did without
the need of additional, sometimes flimsy,
adapters.
The PL380 sounded great, clean, and
quiet (when it needed to be). I used this
amp on a large, last-minute Latin concert
where I had to add two more EAW SB850
subs per side. The PL380 held up, and
even sounded beefier and punchier than
what I already had in my racks. With 2,500
watts per channel at 4 ohms, the PL380
exceeded my expectations. It was also
good to find out that I could drive this
amp hard for hours without it having any
problems.
The next time out was on a simple
corporate “talking heads” gig. I needed to
add some front fills in, as the hotel ball-
room was wider than I was expected. I
knew I did not need an amp as powerful
as the PL380, but it was what I had left in
the shop. Needless to say, the PL380
sounded great and powered Community
Veris 6s just fine. I even used it to power
some EAW JF100s for a lobby plasma
screen presentation at a corporate ball-
room show, and sent it out once with a DJ
and some full-range speakers just to see
what it would do. It responded great. Yes,
it was some serious overkill, but it proved
its versatility. Since then, I have used the
PL380 on almost every show as my total
utilitarian amp — I’d just grab it and go!
At every show, the PL380 outperformed
almost everything else I owned. The sonic
quality was fantastic, from subs to high
end to full range cabinets, with more
power than you would need for anything
in almost every arsenal. It ran cool and
quiet and never thermaled, never shut
down, and never left me hanging.
| SUMMARY
Today, there are more amplifier choices
flooding you than you can wrap your
head around or even have time to audi-
tion. QSC’s PL380, however, stands out as
a simply great product at a great price,
offering the “Swiss Army Knife” of amps.
David Rittenhouse is the senior sales execu-
tive and A1 engineer at Event EQ in Baltimore,
MD, and a regular contributor to PAR .
Copyright 2008 JRS Publishing (USA), Inc. Reprinted with permission. Reprinted from Pro Audio Review
PRODUCTPOINTS
SCORE
Overall, a powerful improvement over the older series.
• Powerful
• Lightweight
• Great utility amp
• No DSP without additional gear

Copyright 2008 JRS Publishing (USA), Inc. Reprinted with permission. Reprinted from Pro Audio Review
BENCH TEST
QSC PL380 Power Amplifier
BENCH MEASUREMENT DATA
Maximum Power (1 kHz, 1% THD)
(See Notes)
Stereo 8-ohm loads 1.4 kW, 31.5 dBW
Stereo 4-ohm loads 2.3 kW, 33.6 dBW
Stereo 2-ohm loads 3.0 kW, 34.8 dBW
Bridged 4 ohm load 6.0 kW, 37.8 dBW
Dynamic Output Power
Stereo 8 ohm loads 1.8 kW, 32.6 dBW
Stereo 4 ohm loads 3.6 kW, 35.6 dBW
Stereo 2 ohm loads 6.0 kW, 37.8 dBW
Bridged 4 ohm loads 12.0 kW, 40.8 dBW
Dynamic Headroom
Stereo 8 ohm loads 1.1 dB
Stereo 4 ohm loads 1.9 dB
Stereo 4 ohm loads 3.0 dB
THD+N at near rated power (20 Hz - 20 kHz)
Stereo 8 ohm loads
<0.02% @ 1.0 kW, 20 Hz – 2 kHz
< 0.6% @ 1.0 kW, 20 kHz
Stereo 4 ohm loads
<0.05% @ 1.5 kW, 20 Hz – 2 kHz
< 1.0% @ 1.5 kW, 20 kHz
THD+N at 10W output (20 Hz - 20 kHz)
Stereo 8 ohm loads < 0.08%
Stereo 4 ohm loads < 0.1%
Damping Factor, 50 Hz re 8 ohm 206
Output Impedance magnitude at:
50Hz 38.8 milliohm
1 kHz 57.4 milliohm
5 kHz 196.7 milliohm
10 kHz 393.9 milliohm
20 kHz 867.9 milliohm
Input Impedance 14.7 kilohm
Frequency Response, 4-ohm load
20 Hz - 20 kHz +/- 0.0 dB
- 3 dB at < 10 Hz, 58 kHz
Voltage Gain, 8-ohm load, vs. gain setting
26 dB 21.2X, 26.5 dB
32 dB 41.8X, 32.4 dB
1.2V 92.1X, 39.3 dB
Sensitivity for 0 dBW, 8-ohm load
26 dB 133 mv, -15.3 dBu
32 dB 67.7 mv, -21.2 dBu
1.2V 30.7 mv, -28.0 dBu
Sensitivity for rated output, 1.5 kW, 8-ohm
26 dB 5.17 V, 16.5 dBu
32 dB 3.62 V, 13.4 dBu
1.2V 1.12 V, 3.2 dBu
Output noise, 32 dB gain setting, Ch1/Ch2
(essentially gain setting Independent)
Wideband
110/200 mV | -28.2/-23.0 dBW
A - Wtd
816/852 uV | -70.8/-70.4 dBW
Signal to noise ratio re: 1.5 kW into 8
ohm, 32 dB gain setting
A - Wtd 102.4 dB
Channel Separation, 20 Hz - 20 kHz
Ch 1 > 2 , Ch 2 > 1 > 50 dB
Power draw @ idle 153 W, 0.58 PF, 2.2A
Notes: Unless otherwise noted or implied, all
measurements are made with 8-ohm loads from
the balanced XLR inputs, stereo mode with the
volume set to maximum and gain set for 32 dB.
Both channels driven for all distortion and power
measurements. Measurements made on one
channel are made on channel two.
Power output measurements were limited
by the regulation and resultant voltage drop
under power of my AC supply.
BENCH MEASUREMENT COMMENTARY
The QSC PL380 is one brute of an amplifi-
er! This most powerful of the PL series utilizes
both a switchmode power supply and a Class
D switching power amplifier circuit. This one
definitely exceeded the regulation capacity of
my external AC supply fed from a sub-panel
outside of my lab. My load resistors could
take it for the relatively short time of the dis-
tortion vs. power tests.
Class D amplifiers in general have an out of
band high frequency response that is a func-
tion of load impedance value due to their nec-
essary LC output filters. The PL380 has this
relatively controlled. This is shown in Fig. 1 for
frequencies greater than 10 kHz and loads of
open circuit, 8, & 4 ohm. Low frequency
response was very extended. This is plotted
in Fig. 2 along with the response of the two
low-cut filter positions of 30 & 50 Hz.
THD+N for a 1 kHz test signal and for 8,
4, and 2 ohm loading in the stereo mode are
shown in Fig. 3. Distortion is reasonably low
and noise dominated up to about 10W and
then begins to rise with 8-ohm loading. The
lower impedance loads cause more distor-
tion above the 10W level which is not sur-
prising. As mentioned above, my AC supply
couldn’t hold the voltage up enough under
this VERY high amperage load to make the
rated power at the lower loads. But still, 3
kW per channel ain’t bad! No doubt the amp
would meet it’s ratings with a maintained
120V AC line input.
Plotting THD+N as a function of frequency
and power for 4 ohm loading, distortion is low
up to about 2 kHz, where it begins to rise and
gets to pretty high values above 10 kHz at the
1.5 kW and higher levels. The 1 & 10W levels
are noise dominated.
The damping factor vs. frequency shows an
unusual, in my experience, increase in DF
below about 50 Hz.
In terms of Channel separation, unusual is
the more or less flat nature of the separation
vs. frequency. Much more usual is a charac-
teristic that rises with frequency due to capac-
itive coupling in the signal circuitry.
— Bascom King
Fig. 1: Frequency response at the 1W/8 ohm
level as a function
Fig. 2: Frequency response of the Low and High
cut filters. Red = Flat, Magenta = 30 Hz low cut,
Blue = 50 Hz low cut
Fig. 3: THD+N of 1 kHz signal vs. power output
for 8, 4, & 2 ohm loading, bottom to top at 100W