Ultra2 Hardware
THX Ultra2 also raised the bar for speaker performance.
While output, sensitivity, and distortion requirements stayed the same, off-axis performance requirements changed dramatically.
THX also changed how
they measure the performance.
Smoothness of off-axis performance is now emphasized rather than
attenuation as called for in Ultra. Recent research makes it clear
that speakers with off-axis performance which is completely free of peaks
and dips in amplitude response sound better that those with peaks and dips
(even if attenuated). If a room has unacceptably strong ceiling and floor
reflections, it is possible to correct that with acoustical treatments
(something more and more consumers are willing to do), but poor off-axis
linearity is something you can't fix after the fact.
They've also broken up the linearity requirement with Ultra2
into three bands of the audible frequency spectrum: Low, mid, and high. The
± dB window is quite tight in the
mid-band, with greater variation allowed for the low and high. This requires
that a speaker be quite accurate in the critical mid-band while still giving
the designer enough latitude to keep their company’s signature
"voicing". Frankly, we find this last item a little disappointing,
since we are
somewhat opposed to the notion that a speaker should ever have
any sort of unique "character". THX's answer is that they
realize no speaker is absolutely 100% perfect in this respect, and their
banding of the spectrum simply forces a manufacturer to concentrate the
greatest effort on the band that matters most.
In addition, subwoofers now need to be anechoically flat to 20 Hz.
THX did this because their research shows it give them a better match with the rolled-off energy from the satellite
speaker. Because these new subs may
get shoved into a corner and end up with TOO MUCH at the bottom end,
THX Ultra2 controllers include a Boundary Gain Compensation which, when
selected during set-up, rolls-off the bottom end of the subwoofer signal to
compensate if an Ultra2 sub is getting too much help from the room itself.
Select2
In 2005, THX Select was revamped to Select2.
Intuitively, Select2 inherits from Ultra2 the ASA (Advanced Speaker Array)
along with the modes that use it: THX Select2 Cinema, THX Music,
and THX Game. As such, support for 7.1 speaker configuration is no longer
optional as it was with Select (products can include only five channels
of amplification, but they must provide the full 7.1 line-level output).
The S/N (signal to noise) requirement was increased 9 dB with Select2. THX tells us
that while, at first, some manufacturers grumbled at the extra design work that would
take, all certified products have managed to meet the new requirement.
Some Things We're Not Crazy About
Metrics Tested on THX DVD Players:
Video Level
Sync Level
Bar Tilt
2T K Factor
Pulse/Bar Ratio
Sin x/x Response
Sin x/x Group Delay
Chroma Level
Composite and Y/C Chroma Delay
Chroma Differential Gain
Chroma Differential Phase
Burst Amplitude Differential
Flesh Tone Phase Error
Luminance Linearity
AM Chroma Noise
PM Chroma Noise
Chroma Correlated Noise (IM)
Chroma Burst Frequency Leakage in Y
Chroma Burst Frequency
H Sync Timing |
In 1998, THX launched certification for DVD Players, and we
were a little disappointed to say the least. While on paper their
goals for DVD Player design are first rate (see metrics list at right), they
quickly brought their testing and certification integrity to question with the very first Certified
DVD Players such as the Pionner DV-09. More recent offerings from the likes of Denon fair much
better, but we would be remiss if we were to not mention this "sour" launch
and there are still models which fall well short of our own Benchmark.
Another THX product which leaves us scratching our heads is
cables, and that's NOT a reflection on THX. It's no secret cables are a
high margin item, but the THX cables we've seen take it to a
whole new level. It's important to remember that THX doesn't tell
people how to price or market their products. If a cable or wire
passes the signal for which it is intended with acceptable integrity, THX
will give it a license to use their name. They can't help it if the
licensee goes on to position and price the product as something it is not.
In fact, some of the THX interconnects we've played with employ ridiculously
tight RCAs which only give a false impression of superior connection while
introducing the risk of breaking your equipment from the force required to
plug or unplug them.
One nice thing about THX and cables, however, and
indeed the I/O jacks on THX equipment, is that they have a comprehensive
color coding scheme. Unfortunately, THX has not pushed it as hard as
they should have, and most products either fail to use the color coding
scheme, or don't use it comprehensively. Another nice THX cable thing
that THX let go of was their standard for a single DB-25 multi-channel connection. My 10 year old Rotel
five-channel THX amplifier has this input. If I had a THX controller
with the corresponding output, I would have only one cable between them, not
five. THX tells us it fell by the wayside because no one was willing
to put it on their product for fear of it being seen (incorrectly) as a "degraded signal
path".
As far as THX DVD titles, every one we've come across has
exquisite sound, but on occasion perfection in the video
quality is debatable. It might be excellent, but not exquisite. Some titles exhibit the all too
common halo/ringing artifact, but further investigation is warranted before
we pass final judgment (it has been suggested that, at least in the case of Lucasfilm's own Star Wars Episode I, it was an artifact of the green
screen process which "crept through" to the hi-def master).
THX-like Settings
Myth: "THX
equipment only works with other THX equipment."
Reality: Any THX piece can be used with non-THX
equipment, though in certain situations you may end up loosing some of
the benefits. For example, using THX speakers with a non-THX
crossover will result in a less than perfect subwoofer/speaker splice. |
You can get some of the THX benefits without actually having THX-certified
equipment.
Many non-THX receivers are using the same combination of
bass management crossover slopes as THX, and simply using a THX speaker set,
or a non-THX set with
the same FR alignment, will net you the same perfect
crossover. Although difficult to find and identify, there are properly
designed dipole speakers which are not THX-Certified (Paradigm models come
to mind).
There are many examples of excellent, non-THX high power amplifiers
which will fit right in with the rest of the THX pieces, though if you are
picky, you'll want to do your homework to make sure it mates perfectly with
the rest of your stuff.
We've already mentioned not worrying about THX-Certified cables.
And, you can look at our own DVD Player Benchmark to find out
what you need to know when picking a player.
You could (and should!) acoustically treat your room, and as
a result be able to accommodate a wider variety of speakers, maybe even negate the benefits of
Re-Eq, but even
in that situation, THX equipment can't hurt, so you might as well put some on
your shopping list.
Click Here to Go to Part VI.