| Video Noise November 2002
Integrating High-Quality Stereo with Home Theater
There are a lot of audiophiles
struggling with the question of how to integrate home theater with their existing
audiophile-grade stereo system. I get a lot of e-mail on this topic, and each time the
writer is struggling with similar questions. Since I’ve been there and done that,
perhaps my experiences will ease fears of messing up an excellent stereo system. Those who
haven’t read my "Max
dB" columns in SoundStage! may not know that I started out as a serious
two-channel audiophile. If I went from "stereo only" to a fully integrated
stereo and home-theater system, anybody can.
A big TV in the middle will mess up my
imaging/soundstage/depth.
Not necessarily. A great music system can coexist with a TV
in the middle. You can take some steps to minimize the effect of the box. The
smaller the box in the middle, the better. The sturdier the box in the middle, the better.
The less resonant the box in the middle, the better.
You should dampen plastic and MDF cabinets with
peel-and-stick linoleum squares cut to fit inside cabinet surfaces. If one layer of
linoleum seems too light for the panel in question, stick a second layer on top of the
first for the additional benefits of constrained-layer damping. Larger cabinets like
rear-projection TVs can have bracing glued inside -- let plenty of air circulate while the
glue dries so nothing deposits on the mirrors or screen.
The larger the glass or plastic screen surface, the more
hard-sounding reflections you will get. These are easily tamed for music listening by
covering the screen with an appropriate material. Use something that’s not too heavy,
not too absorbent, and not too deadening. Finding the right material will take some trial
and error, but you’ll know you have it when you hear it. Experiment with common
household items first to learn what sort of material is most appropriate. Allow this
material to cover the sides and back of the TV also. Lightweight felt from a fabric store
may end up being perfect.
Keep the screen slightly behind the main loudspeakers to
minimize imaging problems -- six inches is enough to help quite a bit. Even three inches
back is better than even with, or slightly ahead of, the loudspeakers.
I, too, was nearly frozen by big-box-in-the-middle paranoia
-- so frozen that I put the monitor on a stand with casters so it could be rolled to the
back of the room and covered up for critical stereo listening. For a year I did this
religiously. Then late one night I just wanted to relax and listen to some music so I
threw on Dire Straits' Love Over Gold LP, the domestic Warner Brothers version, but
pressed on remarkably silent Quiex II vinyl. This LP creates a huge soundscape in
the room. That night I didn’t really care if playback was perfect; I just wanted to
be transported into the music. What I got was essentially the same thing I was getting
with the TV in the back of the room and covered up. The sound wasn't identical, but there
was essentially no loss of spaciousness, and imaging was still pinpoint with some sounds
way off in the distance and others front and center.
I went through six months of convincing myself I
wasn’t missing much by not moving the TV to the back of the room. With the simple
tweaks mentioned above, all reservations about having the TV in the middle finally
disappeared.
How do I connect everything so I still use my preamp for
stereo music?
Connect the front left and right outputs of the surround
processor to the video inputs of the preamp. Set the preamp’s volume controls to the
same level you normally use for CD or LP playback. Always make sure the controls are set
to that exact position every time you switch the system to "Video" for home
theater. If you have a stepped attenuator for volume, this is easy. If you have a
continuous non-stepped attenuator, you will probably want to make a "pointer" of
some sort so you can easily set the volume control to the correct position. The surround
processor is used to set the actual level for the front left and right speakers so they
match the other speakers for TV and movies -- or, horrors, music in surround sound. Some
newer preamps, even some new tube preamps, have "pass through" connections that
bypass all circuitry and the volume controls for the ultimate in easy integration of
stereo and surround sound.
What about connections to amps and speakers?
The best approach here is to put the outboard amplifiers
closer to the speakers and use longer interconnects. This will produce the best sound by
keeping speaker cables shorter. It will also keep cable costs lower since interconnects
are usually cheaper than speaker cables of similar performance.
Last time I tried combining the systems, I had a hum
problem.
This is almost always a cable TV issue. You need to isolate
the cable TV’s ground from your music-system ground. There are a number of products
made to allow you to do this. Prices run from around $25 to $150. You can do it cheaply by
purchasing two 75-ohm-to-300-ohm converters. Connect the two 300-ohm ends together, left
wire to left wire, right to right. Plug the cable-TV cable into one end and connect the
other end to your monitor or cable box. If the hum stops, you found the problem. If you
have digital cable you’ll need a couple of pretty-darn-good converters with
high-enough bandwidth to pass the high-frequency digital channels without losing signal
strength. Look for converters rated for 1GHz or more.
Another common hum-killing technique is to run an 18- or
20-gauge wire from component to component until you find the two causing the hum problem.
Connect the wire permanently and the hum will be banished. Usually the two components in
question will have two-wire power cords. Occasionally you may have to ground a two-wire
power-cord component to another component with a three-wire/three-prong power cord to stop
the hum.
Extra speakers in the room are supposed to kill the
sound. I don’t want that.
Unless you add more than five or six speakers, the extra
speakers won’t harm anything. Once you have seven speakers and five subwoofers in the
room, you’ll understand that you can still hear Love Over Gold in all of its
sonic glory with no loss of spaciousness, no loss of bass power, and no loss of detail or
harmonic content.
My speakers are six years old. They didn’t make
center or surround speakers back then.
Check with the manufacturer. You may be surprised to find
that they have current center-channels, surrounds, and subwoofers that match much better
than alternatives from other speaker manufacturers. You want all the speakers to be close
in sonic character. Perfect matching is ideal, but in the real world, if the match
isn’t perfect, you won’t ruin the system’s sound. You do want to have all
the speakers similar in character so there aren’t obvious coloration
differences from channel to channel.
Is there a way to minimize the number of components I
need?
There are some things starting to happen now that might
make it possible to combine stereo and home theater with a very limited number of
components. You would use a multichannel preamp combined with a DVD player that has full
internal processing, setup, and bass-management capabilities. The DVD player would need
one or two digital audio inputs so its internal surround decoding could be used to process
digital surround sound from other sources like broadcast TV, cable TV, satellite TV,
D-VHS, etc. Analog sources would go to the multichannel preamp as stereo inputs. Some DVD
players may even contain analog-to-digital conversion that would allow you to input stereo
analog and output multichannel surround sound into the multichannel preamp.
DVD players with full-featured processing and bass
management have been around for a while, but digital inputs and analog inputs are just
beginning to appear. With this arrangement, the DVD player essentially becomes the
surround-sound processor for the system and the multichannel preamp drives the amplifiers
that drive the speakers. A multichannel preamp may not be needed if the DVD player’s
output stage is beefy enough because it could drive the external amplifiers directly,
though access to volume control may require several key presses on the DVD player's remote
control.
...Doug Blackburn
db@hometheatersound.com |
