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Q I enjoyed reading Sandy's HTPC article, but am not sure WHY? I
understand what a good ATI or nVidia card can do, the scalers, etc. Has anyone
SHOWN what an HTPC can do vs. a good Panasonic (RP82 or 91) player? Sandy
mentions pros and cons, then lists under pros the fact that it costs <$1000 to
build - agreed but very good prog scan DVD players are far, far cheaper. If it's
so good, someone surely can capture the difference in still digital images for
everyone to see. I must be missing something - if so, please explain.
A The advantages of an HTPC are that you will be able to customize
the output according to your needs, including a scaler PC card to scale the
image to your exact projector resolution. Also, you will be able to upgrade the
various software programs as they are improved, eliminating artifacts as they
are discovered and fixed in the programs.
T
Q I had some interesting/disturbing results from
doing 20 Hz - 150 Hz frequency sweeps. My subwoofer and center speaker responded as I
expected. The center speaker rolled off very smoothly from 100Hz down. I can't
say the same for the rear surrounds and front towers which all responded with
peaks and dips and more peaks. The towers sit on a hardwood floor. What's the
best way to isolate them from the floor without using spikes digging into the
wood? The rear surrounds are mounted near the ceiling and ~6" or so from
corners. Is there some material I can use to kill the <100 Hz frequencies? Due
to WAF, my only other option is to put the surrounds on the floor under tables.
A General wall treatments
work well for mid and high frequencies, but not for the bass. You might try some
bass traps, such as those sold by ASC (http://www.tubetrap.com/),
Auralex (http://www.auralex.com/main.html),
or you can make them yourself (http://ic.net/~jtgale/diy2.htm).
To isolate your speakers from a hardwood floor without having to use spikes, get
some felt furniture pads at a hardware store. I get the ones that are about 2" x
2" and double them up before putting them under each corner of the speaker.
The bass problems you are having are most likely more a function of room
dimensions and such. While bass traps are probably a valid way to address the
problem given enough money and time (most likely a lot) spent tuning the trap to
respective frequencies and optimizing location, the most direct, and probably
best scenario, is to kill frequencies below 100 Hz at the source, through bass
management. You state that your subwoofer is responding as expected. If that
means desired, then you are guaranteed good results simply by re-routing the
bass to the subwoofer. Bass traps may or may not work, and if they do work, it
may be a lot of time and expense to make that the case, so I thought the easy,
cost-free alternative should be mentioned. If the crossover frequency range
won't allow you to completely eliminate the problems, it at least narrows the
problematic range, which becomes much easier to deal with.
T
Q I need a DVD player in the
$200 range, with no chroma bug. Any recommendations?
A The new Panasonic RP-82 can
be had on the Internet for that kind of price. It is chroma bug free.
T
Q Just thought I'd give some
help to one of your readers regarding the last question from the 7/14 issue.
I've built several subwoofers, and have heard just about every sound they're not
supposed to make. I don't know what the flapping is, but here are some
suggestions:
If the sound is a "ch ch ch ch ch" sound at a higher frequency than normally
comes from the sub, there is a leak somewhere in the box. If this is the case,
you can feel the air escaping with your hand. A commons source is a bad seal
around the driver or the amp, or a tear in the driver's surround (probably poor
workmanship, i.e., return it for another). But it could also be coming out of
the gaps around the amp's switches and knobs. This would be a design defect.
If the sound is more of a "whoo whoo whoo" (like blowing over the top of a
bottle), it's probably port chuffing, a design deficiency, i.e., return it for a
different model. You can hear this by listening near the port.
If it's a "click click click" or "pop pop pop", the driver is smacking its
excursion limits - you need a bigger sub. A 10" sub needs >10mm of one-way
excursion to reproduce satisfying levels. This is rare in an inexpensive sub.
Another source of "flapping" could be a wayward wire getting smacked by the
cone. A look inside will tell you, but if the sub is under warranty, trade it
for another.
If the sub is ported, maybe something has gotten in through the port and is
bouncing around. This is generally pretty obvious, though.
I've never heard a sound like this go away after break-in. NHT knows their subs,
so I'd suspect a workmanship problem.
A Thanks for the info. If
you can record these sounds when you come across them again, send us the wav
files, and we will post them.
T
Q I recently purchased a Denon 2802 receiver. I am
very pleased with it, except for one issue. For the life of me, I can't figure out
how to connect my graphic equalizer to the receiver. It does not have the typical
Tape/Monitor connections. Can it be done?
A If the receiver has a main
pre-out and a main-in, which usually has a U hook connecting the two, pull the
hook out, and put your equalizer between the pre-out and the main-in.
T
Q There was some confusion on
the forums about your statement on Sony and Philips DVD players with or without
the chroma bug. Can you clarify?
A We have not tested the specific players that the
reader had asked about, but we have just not yet seen any players from those two
manufacturers without the bug. I added a sentence on that to Q&A 299. Philips
announced a fix specifically for the Q50, but we want to see some of the new
Philips players.
T
Q I have a Panasonic PT-61HX41 TV and a Panasonic
DVD-RP56 DVD player. I have read articles on how some HD-Ready PTVs lock into
full mode when receiving 480p signals and makes it difficult to view DVDs in Pan
& Scan or non-anamorphic aspect ratios. So, I'm just writing to find out if my
TV locks into full mode. If it does, what DVD player do you recommend?
A If you have both the RP56 and the TV, it is easy
enough to find out. Just try and change the aspect ratio on your TV while
feeding it the 480p from your DVD player. The TV is the problem, not the player.
T
Q I am about to update my surround system to
Digital Dolby, etc. from Dolby Pro Logic. I also will use the system for music.
My room is roughly 16x19x8 and I am considering the Anthem AVM-20 and PVA 7 with
Magnepan 1.6 front, MG 12 surrounds, and MGCC2 center and a REL Q201 sub.
I am unable to decide if dipole speakers for the surround channels would be
preferable. I have read then since the full spectrum of audio is represented in
the surround channels with Dolby Digital that standard speakers my be
preferable, while others continue to advocate dipoles.
A
Movie theaters, going back to the first surround sound systems used on 70mm film
in the 50s and 60s, have never employed a pair of speakers in the back corners
of the room for surround sound. They used, and continue to use, multiple
speakers in an array (or more recently multiple arrays). The "surrounds"
therefore are fundamentally different from the front in
terms of both their use and execution from the "screen" channels in a motion
picture soundtrack system.
Dipole speakers as surrounds are intended to parallel the surround speaker
arrays of the cinema in a home environment as much as possible. In the beginning, THX actually considered mandating multiple smalls
speakers for the surround channel(s) but realized almost no consumer would be
willing to go that far, and those that were willing would run a high risk of
getting it wrong. Dipoles were the obvious compromise. A workable answer.
They are not without drawbacks. When placed correctly, by nature their
sound is comprised of many reflections arriving at different times with varying
timber. Time alignment becomes a joke with them. Localization of the
sound is almost not possible making them mostly successful if you assume that's
what the sound artist wanted.
Cinemas have not changed. In this day of Dolby Digital, Surround EX, DTS, and
SDDS, cinemas are STILL using speaker arrays for surround sound and the reasons
to chose dipoles therefore has not changed. If you bought into the dipole
thing during the Pro Logic days, you should still be buying into it now.
True dipoles by nature do not have deep bass (some designs do, but that's
another topic). But to say with full bandwidth in the surrounds of these new
formats dipoles are out the window is not correct. Back to the theater again,
the surround speaker arrays are not terrific bass transducers themselves.
Soundtrack artists know this, and if they are doing their job, they will refrain
from putting deep bass effects exclusively there. Some (many?) soundtracks do
have deep bass in the surround though and yet still this is not a reason to
throw dipoles out. We should be using the bass management of
our surround sound system!!! I cannot think of a surround sound speaker, of any
design, for which the full signal is appropriate. Subwoofers are not just for
the LFE channel: they are for DEEP BASS in general.
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