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Review NaN of
, from carrollton, tx Summary:
Note: This review is for the Citation 7.4, not the 5.4
I purchased the Citation 7.4 subwoofer new from
an ebay auction. I am away from my house most of
the time so I have not given it a very complete
evaluation in terms of listening time, but I do
have some early opinions about it.
The Citation 7.4 is a passive sub. This means that
it does not have its own amplifier. All 5.1/Dolby-
Digital/DTS receivers provide only "line-level" drive
for the subwoofer, so all subwoofers need a separate
amplifier. Most subwoofers have their own amplifier,
often noticeable by a low-profile vertical finned
heat sink on the back. The Citation 7.4 needs an
external amp. In my opinion, this is a virtue, because
that you get to pick the amp yourself. (more on this later)
Many of the under $500 (under $1000?) subwoofer amps are
"class G" switching amplifiers, which means they are not
much more than voltage-controlled bi-polar switching power
supplies. This lets the voltage stepdown occur at 50Khz or
so, instead of a 60Hz wall frequency. Inductive coupling
is much more efficient (there is more and sharper current
transitions) and at least the power supply can run very
cool, and for switching transistor output stages (class G)
the whole thing can run cool and be very compact. The
problem is that all of this switching creates noise
that can easily find its way into the output and onto the
subwoofer driver. If you look at the signal on an
oscilloscope, you will see a visual buzz superimposed
That idea is not pleasing to me, because even though
my ears can tolerate "harmonic distortion" (THD) (ie.
I like the sound of tube preamps), I hate any noticeable
hum or buzz. And switching amps are susceptible to this.
The reason why you can often get away with it is that
most big subwoofer drivers (the loudspeaker cone) don't
respond at buzz frequencies. (If you stick your ear up
close to the speaker you might hear it faintly)
Therefore, you don't want a cheap switching amp. You
want a solid linear amp with a big transformer and power
capacitors. The heavier in mass the better, as these
tend to have a higher "damping factor", meaning that energy
is transfered to the speaker the way the signal says to
do it, instead of having the stored mechanical and acoustical
energy bounce back and forth between the speaker and the
amp. (A contributor to the undesirable "booming" sound").
Getting back to the Citation 7.4, it comes in a UPS-proof
double box, about 90lbs. The speaker itself is thin-foam covered.
The outer box contains big corner supports which adds 4" of
clearance all around. This is *important* in a mail order/ubid/ebay
environment, because speaker boxes get handled roughly and
dropped; and the heavy ones get severely cussed at.
My shipment even came on its on wood pallet!
The color of the speaker is speaker black, with an (I think)
ash veneer. The grill is black and has a very clean fit and
look. The cabinet is solid. As a comparison test, go to BB or CC
and move around a JBL 12" or 15" sub. It is surprisingly light.
Now put your ear close to the side of the box and give the
top of the box a light rap with your knuckle. NOT TOO HARD!
Or you will hurt your ear, because the JBL box is poorly
damped and will resonate with a strong ping that really can
hurt your ear if it is too close. (same warning if you use
a stethoscope). The Citation is much better damped, using
a stronger 3/4" particle board (maybe MDF) construction.
The size is such that it makes a great side table for a sofa.
(subs are not directional, so you can put it anywhere) The
of the Citation has a 3" port, so the Citation was not acoustic
suspension (my preference).
The rear cup is just OK. I took it off and saw that the whole
box was stuffed with polyester for LF damping (that's good).
The connecting spades from the cup to the speaker were wimpy
and so I soldered them on. I did not get to examine the driver
itself, but the specs stated 14" with an 18lb (!) magnet
structure and 6ohm nominal impedance. Comparing this oversized
driver to a BB/CC subwoofer driver would be laughable. (What
would you rather have: a 15" cone with a 30oz magnet, or a 14"
cone with an 18lb magnet? I rest my case.)
For the amp I bought a Marantz MA700 220/330 watt monoblock,
on sale at ebay for $325. No hum or buzz. There is a gain
control on the back of the MA700 to adjust. This setup of
MA700+Citation7.4 was a good match.
The Citation will output human voice (500Hz) (I tried this).
I was using an older pro-logic Yamaha 592 as a source for the
subwoofer output, and it does not have much of a LF cutoff,
so I stuck in a Teac equalizer as an active filter. That worked
good, but I don't know what it did to my phase response
(as if I actually care about phase response)
Of course, being a passive sub, there are not controls on
the sub. These would be for the sub amplifier. With
most powered subs you get a gain knob (you need this with
what ever sub amp you choose), a phase knob would be OK
(this is for uncharacterizable perturbations from placing
the sub at an arbitrary point in the room) but not mandatory,
and main speaker in/out. This last feature provided by
powered subs is a joke. There is no way that I am connecting
my main speakers through some subwoofer-supplied compromise
of a highpass filter. (ie. you don't want this feature)
Subjectively, I loved the sound. No boominess with music
(all I had on hand was Bocelli Sings Bellagio and Manheim
Steamroller Christmas). I was a little bit concerned at
first, since the Citation is a tuned port (not sealed box),
but the "Q" is not too high at all. This give the "musicality"
to the sub. (By this I mean that it tracks the music just
right without a muffled-ness, and does not linger on with
false echoes after the sound is over). Turning the MA700 amp
on and off (an easy A/B test) demonstrated the "fullness"
the sub added to the music. I played my Das Boot DVD and
thought I was 140m underwater; just for fun, I turned things
up loud, Very loud. For the rivet-popping scene. I still
wake up in cold sweats.
Bottom line:
(1) Modern sound systems must have a sub, and the
Citation 7.4 is a really solid one.
(2) You want a high quality amp for the sub, so
plan on spending around $300 more for this.
(3) If you have a modern DD/DTS receiver, you can
use its subwoofer output directly, especially if it
has a variable cutoff frequency. Otherwise you will
benefit from a lowpass crossover/filter to keep highs
out of the sub.
I am going to give this speaker a 4. It is
the best in its class (under $1000 passive) (I know the
list is a little higher than that but you will pay
far less than $1000 for it). To get a 5 from me would
require a more solid cup/connector/spade. For value,
if a passive sub is for you (ie. if you are at all
a do-it-yourselfer and not an appliance operator that
wants a Home Theatre in a Box), you can't really put
the raw parts together for cheaper than what you might
be lucky enough to get it for on ebay, so sue me, but I'm
giving it a 5.
Strengths:
this sub does what is asked of it
solidly built. Won't vibrate itself into the music
Weaknesses:
Passive. This is not a weakness. But you do need an amp for it Similar Products Used:
JBL,Infinity,Bose mass market subs. (store eval only, not actually owned)
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