What is an HTPC?

An HTPC is really just a PC with some carefully chosen components.  Like a
good quality video card, sound card that can handle Dolby Digital, and
usually a video input or tuner card.  The cool thing about HTPC's vs scalers
for digital projectors like LCD and DLP is that the PC's output can be
matched exactly to the projector's native resolution and bypass the internal
scaler in the projector altogether.  I've read about some shoot outs between
a decent HTPC (cost maybe $1200) and a $30,000 Faroudja scaler where the
HTPC was judged to have the superior picture.  It made a huge difference in
picture quality for me.  The downside is that they take a fair amount of
computer savvy and willingness to tinker to get and keep them performing.
There are some commercially available models (from www.digitalconnection.com, www.cellercinemas.com and others) that can reduce this requirement.

Answers to questions, comments, plus some rants and raves.  Your questions welcome!
How is an SVGA projector for DVD's?

I like it, from a viewing distance of 13 feet on a 7' wide screen, the "screen door" effect is normally not visible, except in bright areas, and then not distracting. I would like XGA better.

The real problem with 800x600 is that you are "throwing away" resolution with anamorphic (widescreen) DVD's.  A DVD has 480 vertical lines of resolution, which is more than covered by the 600 "lines" of an fixed panel SVGA display for "standard" 4:3 aspect ratio material.  With a 1.85:1 widescreen DVD you only use 432 vertical lines (loose 9%). 2.35:1 movies are letterboxed inside a 16x9 frame so you only loose 9% there also.  The full 720 pixel horizontal resolution is supported which helps make up for this.

This issue seems to be mitigated somewhat by using an HTPC which does a better job of scaling the image, plus matching the projector's native resolution results in a very sharp image, more so than using the S-video or component inputs. 

An anamorphic lens, like Cygnus' Panamorph, that provides vertical image compression can allow you to use the full 600 vertical lines of reslolution and increase contrast ratio by bringing all the pixels available to bear.  Unfortunately these lenses cost as much as an SVGA projector.

There are now DLP projectors that employ a "dual mode" DMD that can actually put more pixels to "work". Most SVGA projectors that have a 16x9 mode actually just squeeze the picture onto a narrower band of pixels to make it appear correctly.  The Infocus LS110 and Plus Piano incorporate this feature.

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I'm thinking about getting a less expensive Sony Projector VPL-CS3, -HS1 (Cineza), CX1, etc. What do you think?

I would think twice about it. My main reason for this is contrast ratio.  A second reason is XGA (VPL-CX1 has XGA) resolution, but that implies a jump in cost. 

From the published specs the Cineza is very similar to the Sony VPL-CS3 and it's predecessor the VPL-CS1.  The CS3 has 700 lumens vs the CS1's 600, but they use the same lamp, as does the Cineza (HS1). 

Sony does not publish contrast ratios for these units, but I have found reviews that list it at 66:1 to 130:1, out of the box.  The Cineza may be better, I couldn't find anything that listed it specifically.  Since it uses the same 0.7" LCD panels, I suspect it is similar.  The UHP lamp that these units use is skewed towards blue and on the "high" color setting has a color temperature as high as 11000K! Some of these shortcomings may be "tweaked" for improvement, for example, I use a red color correcting filter on my projector and a grey screen.  The red filter blocks the excessive blue light component and the grey screen absorbs some of the light to give a better apparent contrast ratio.  With these tweaks I would estimate that the contrast ratio can be improved to the 200:1 range. 

Don't be intimidated by all this techno-babble, there are some very positve features; good vivid colors (especially when corrected and calibrated), low noise, good lamp life, low initial cost, good three year warranty.

Depending on your location some other competitors to consider in the sub $2500 street price range are the Sanyo PLC-XW15 (clones include Eiki LC-XM1, Boxlight MP-5T, & Canon LV-7105), NEC LTZ150 and LTZ85 (LT150 being a forum fav) and PLUS HE-3100 (maybe close on $$).  See recommendations here.

Bottom line: If you can see it before you buy (or can return) and you like it, and can afford it, go for it. I know you will have a great time using whatever you choose.

1/03 Update:  The latest crop of low priced Home Theater oriented projectors are much improved over the models listed above, with better contrast and better video processing.  The same cautions still hold true for business oriented projectors pressed into home theater service.

Tell me about your speakers; How are the Acoustic Research AR-1's?

They perform well in a home theater application where their high sensitivity and extended frequency response can shine.  They are well matched by the AR-4C center channel (same driver complement).

With their high sensitivity, the AR-1's can be driven to reference level by the modest power of my Denon receiever.  What is reference level?  For movie theaters running Dolby Digital sound the "reference" sound pressure level (SPL) for dialog is 85dB (about twice as loud as a normal close conversation), but with dynamic peaks as high as 105dB (quite loud, will be perceived as being two times louder than dialog level), with a wide frequency response.  To reproduce these levels requires a lot of power.  For example, with a nominal 90dB sensitivity speaker, normal dialog levels will only require about 1/3 of a watt to reproduce, while the peaks will require at least 60 watts of amplifier power! (at 1 meter, not accounting for listening position and room acoustics)  Playing at these reference level, the AR-1's seem to outclass the receiver, they would do even better with more power.  As is, the Denon is capable of driving peak levels to >108dB at the primary listening position.

All this talk of SPL's really deals just with sound intensity, and not frequency response.  The AR-1's specified frequency response is 18Hz to 23KHz +/- 2dB.  This is a very "flat" spec and one that is born out by listening tests.  The titanium dome tweeters can sound extra bright when first turned on, but they warm up quickly.  The bass produced by the 15" woofers married to a 500W Carver Sunfire amp is prodigious.  When I first set up the speakers, the bass seemed a bit mushy, but moving the speakers a few more inches from the wall, and turning the level down to about -1dB cleared it right up.  The bass is now much tighter, due part to the acoustic suspension design.  The imaging is very good, but made even better by "toeing in" the speakers a bit (10 degrees).

If I had to name an MVP of my current HT setup, it would be the AR-1's, their sensitivity and wide dynamic range add much to the impact of the system and the "theater" experience.

Sound Pressure Level (Loudness) Calculator

Input speaker efficiency, number of speakers, amplifier power and listening  position and this calculator returns the expected peak sound pressure level .
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How do you clean and maintain an LCD projector?

Check this link for pictures and a discussion of filter cleaning and "Dust Blob" elimination.
Viewing Distance Calculator

Input viewing distance and screen size to discover how "cinematic" your viewing experiences are.  Use this to plan your seating arrangements and help decide on screen size.
I'm thinking about building a home theater in my basement.  Got any do's and dont's?

I undertook a similar project, here are some things I learned:

- Lay out your room in advance.  Do some drawings or sketches, maybe even try some cut outs that you can move around.  Decide where your equipment will be, what your seating requirements will be, and where it is all going to go.

- Make sure you have at one, preferably two dedicated 20A (12 gauge) electrical circuits with two gang receptacles at your equipment location.

- Put a receptacle above the suspended ceiling for a projector, even if you go with a RPTV now.

- Put conduits in the walls (1" or larger) with one end in a double gang wall box and the other end above the ceiling with a bell cap bushing. Locate these where your equipment will be and maybe another one near the seating area.  This applies mostly to installations with a suspended ceiling.

- Consider putting some poly wrapped fiberglass insulation above the suspended ceiling, at least above the theater, to reduce tile vibrations and sound transmission.  Regular faced R-11 insulation can be used for drywall ceilings.  Add insulation to any hollow walls or spaces (like under a riser) to reduce resonance.

- Down lighting (cans) will vibrate especially in a suspended ceiling.  If you use them, add insulation or isolate the can from the ceiling to minimze vibrations.  Wall sconces are good.

- Consider two layers of drywall plus insulation for any partition walls, that is walls that are not along the foundation walls. These will also vibrate. Plan for acoustic treatment of the room to eliminate first reflections.

- Install dimmers on all your lighting.  Consider using X10, Lutron Spacer or some other sort of remote control system.

- Use a dark decorating scheme, the darker the better.  Especially with front projection.  Any reflected light will contribute to "washing out" the image.

- Pre wire for the surround speakers, at least (maybe all 5 channels).  Consider installing enough cable for a 6.1 or 7.1 system, even if you only have a 5.1 channel system now.

- Don't forget to pre-wire the cable or satellite feed. Also consider a phone line or network drop.  I recommend 3-4 quality RG-6 cables to your HT equipment location.  One or two for incoming satellite or cable feeds, and at least one for a video out from a modulator or satellite receiver.

- If you are installing a projector, consider running the video line for this in advance.  Five quality RG-6 coax cables can be made into an RGBHV (VGA) cable, or component, or S-video cable.  You can also make a cable from CAT 5 cable (see Projects).  If you know what cable you will need, you can install a pre made cable.  Most projectors these days have a serial or USB control port for remote control.  Consider running a cable to accomodate this.

- Heating and air conditioning.  Make sure you have adequate heating an cooling, including at least one air return.  Ducts and grilles can be sources of vibration and noise so make sure yours are secure and possibly even insulated.  For a dedicated room, consider a separate ventillation system.

Do you see a lot of scaling "artifacts" by using an inexpensive projector?
Why didn't you use a progressive scan DVD player?

Actually two very similar questions.

Since all LCD projectors are by nature progressive scan devices, in order to display interlaced video they have an onboard scaler/deinterlacer.  Unfortunately these are not always of high quality. The ones Sony uses are pretty decent, not much in the way of artifacts.  A good quality progressive scan DVD player could help, but the projector would still have to scale the image to its native display resolution.

The key to getting very good video performance from the inexpensive Sony projector has been using a Home Theater PC (HTPC) as a source.  Using the HTPC completely bypasses the projectors on board scaler/deinterlacer.  The resulting picture has a much sharper appearance with better color fidelity.

The achillies heel of LCD projectors is their black level.  LCD panels do not have "tight" shutoff of the light.  Another challenge many digital projectors face is the high color index of the UHP lamps they use.  The lamp spectrum is skewed towards blue, which can give dark scenes a blue cast.  Out of the box, my projector had about a 66:1 contrast ratio (BAD), after calibration and filters it is now at 320:1 (full on/full off) a 480% improvement.
What's the difference between an LCD projector and a DLP projector?

Some key differences:

DLP has a higher "fill factor" than LCD. This refers to the amount of blank space between each projected pixel. Good LCD's have a fill factor of 60%, DLP's more like 80-90%. The fill factor is responsible for the much discussed "screen door" effect. The higher the fill factor, the less screen door.

DLP is reflective, LCD is transmissive. DLP's have higher contrast ratios. Since the LCD panels must turn completely opaque to block the light, and they can't, some light leaks through and causes "grey" blacks. DLP's deflect the light when off, this is better at producing deep blacks, but still not as good as CRT's.

The level of detail each can produce is more a function of the internal scaler/deinterlacer and input source. Some projectors have lousy internal scalers while others have very good ones. The best, sharpest picture is obtained when you match the source to the native projector resolution using a scaler or HTPC. The level of detail should be similar for projectors with the same resolution, moving to a higher resolution (say 800 x 600 to 1024 x768) can result in more detail by using more pixels.

With similar wattage lamps LCD's generally produce more lumens on the screen.

The color wheel in single chip DLP's can produce the "rainbow" effect for some people (caused by the "strobing" effect of sequentially projecting each color through the wheel). Newer projectors with faster wheels and mulitple color segments are less prone to this. Most people do not exeprience this effect, but you should try before you buy.

Many of the top rated HT projectors are DLP ie. Sharp XV10000, Plus Avanti, Marantz, most use the newest Texas Instruments 16 x 9 aspect ratio HD1 DMD chip with a six segment (RGBRGB) color wheel.  The next generation uses Texas Instruments HD2 chip wich offers even higher contrast. 

For more info, see: Video Basics 3, Front Projection.

Front Projection on the Cheap

Always wanted an front projection home theater system, but thought it was to expensive?  Check out these tips for building an affordable system.
Equipment Recommendations
See a list of affordable HT gear I would consider buying.
(Needs an update - update coming soon...)
Can I run my power and audio and/or video cables together?

Paraphrased from EIA/TIA-569A, Pathways and Spaces Standard:

Voice and data telecommunications cabling should not be run adjacent and parallel to power cabling-even along short distances-unless one or both cable types are shielded and grounded. For low-voltage communication cables, a minimum 5-inch distance is required from any fluorescent lighting fixture or power line over 2 kVA and up to 24 inches from any power line over 5 kVA*. In general, telecommuni-cations cabling is routed separately, or several feet away from power cabling

Translated, this means you should try to maintain at least a 5 inch distance between power and audio/video as the load limit for a 20A circuit (80% load per NEC) is less than 2 kVA. Further is always better, if you cannot avoid doing this, at least minimize the length that they run together and ensure the audio/video cable is a shielded model.

Home > FAQ
Video Basics

A series of articles on the basics of choosing a display. Includes basic info about connectors, aspect ratios and display technologies. 
Horizontal Scanning Frequency and Bandwidth Calculator

A calculator for calculating the minimum scanning frequency and bandwidth required to properly display a given video signal.
I'm thinking about buying a used projector, what do you think?

Used projectors can certainly be had for cheaper than new, but there are some trade offs:

- Projector technology is advancing fast and getting cheaper as it goes.  Models that sold for $10,000 or more new a few years ago can be bested by models that sell for $3000 or less now.

-Buying a used projector sight unseen is very risky, there are a lot of things that can get screwed up in a projector.  If you can try before you buy or if you are dealing with a reputable dealer or individual that will let you return it if it doesn't work out then this is a lesser fear.

-Used CRT projectors represent a great value, since more people seem to be looking for good used digitals, used CRT often goes overlooked. (see Cheap Front Projection for a good link to buying used CRT's)

-For used digital projectors I suggest that you stay at 800x600 native resolution or higher, 600 lumens (400 is OK in a dark dark room), and a UHP or UHM lamp.  Stay away from the older metal halide lamps.

-Make sure that the lamp for your projector is still available at a cost you are willing to pay.

If you can see the projector before you buy, here are some things to look for:  These apply mostly to LCD projectors but many are applicable to other projector technologies.

-Project an all white screen, check to see that the image is even in intensity and hue accross the whole screen. Damaged LCD panels or optical components will show up as discolored areas.

-Project an all black screen.  Look for green blobs that indicate a dirty optical path.  You can usually defocus  the lens and bring the dust in to focus to check. This is also a good time to check for stuck pixels, they will show up as colored dots on the black field.  If they are in the middle of the image, they will be distracting.

-Check the noise level, many older projectors have horribly loud cooling fans.  If it's too loud and you like everything else, plan for the extra hassle and expense of a hush box.

-Run some video, use the input you are likely to use.  Look for scaling artifacts (blockiness or jaggedness" and smoothness in pans.  Bring discs you are familiar with, you might bring Avia or Video Essentials, or a disc with THX Optimizer on it to quickly "tune up" the basic settings of contrast and brightness before you run your video.

-Check for gamma and RGB level adjustments, these are handy items to have access to in order to calibrate a proper grey scale.  Many times these are hidden in a "secret" service menu, ask about them.

-Spend a while watching some material you are familiar with, if there is a TV or monitor available that you can compare the screen image with, try it.  It can be a very revealing exercise (direct comparison between a computer monitor and my LCD projector resulted in my switching to CRT, so be warned, this can be a harsh test).

Bottom Line:  Used projectors can be a great way to get started in Front Projection Home Theater, but buyer beware.  If it all possible try before you buy.
Why only an 87" wide screen?  If you have all that room why not go 10'+?

A bit larger screen, say 9-10" wide would be nice, but I've limited it to
87" for a several reasons.  The main limiting factor is the light output of
my projectors, both my LCD which is rated at 600 lumens, and my CRT which is
rated 285 lumens full screen, 1250 lumens at 10% white.  Keeping the screen
in the 100" range has kept the screen illumination close to the SMPTE
recommended 16 ft-lamberts.  My LCD was at 13.5, and the CRT is at 15.
Going larger would dilute the light output and the image would loose

The other reason is viewing angle and source material.  At my viewing
position I have a viewing angle of nearly 37 degrees, which is similar to
what you get in the middle rows of most cinemas.  With DVD material I find
that sitting much closer starts to reveal the limitiation of the source
material, for regular NTSC TV or VHS it is entirely too close.  If you watch
a lot of HD material you can move closer than a 37 degree arc.

Quick Questions with Short Answers
Quick Links
What is an HTPC?
How is an SVGA projector for DVD's?
What do you think about less expensive "business" projectors for home theater?
Tell me about your speakers; How are the Acoustic Research AR-1's?
Do you see a lot of scaling "artifacts" by using an inexpensive projector?
Why didn't you use a progressive scan DVD player?
I'm thinking about building a home theater in my basement.  Got any do's and dont's?
What's the difference between an LCD projector and a DLP projector?
Can I run my power and audio and/or video cables together?
I'm thinking about buying a used projector, what do you think?
Why only an 87" wide screen?  If you have all that room why not go 10'+?
What do you think of surge suppressors and "power regulators"?
What is ANSI contrast ratio, Full On/Off contrast ratio, and what's a good CR?
Should I use an equalizer in my home theater?
What do you think of surge suppressors and "power regulators"?

I highly recommend a good surge suppressor (TVSS) for all home theater systems (or a good  whole house unit is fine also), without one a lightning strike can take out your whole system.  A power line conditioner or regulator is a more dubious addition.  How much benefit you get depends on how good your power is, and how good your equipment is.  A full conditioner/regulator will set you back $500 - $1500.   If you like the peace of mind they provide, or if you have lousy power (frequent brown outs or flickering lights) then you should get one.  I would not buy one expecting that they will make a $2000 system sound like a $20,000 system, ‘cause they won’t.

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What's the difference between ANSI and on/off contrast ratios, and what are do good measured contrast ratios look like?

ANSI CR is also called checkerboard CR because it is determined by displaying a large checkerboard pattern and then measuring the light levels in the dark squares and the light squares.  The CR is then the ratio of the light square measurement to the dark square measurement.   These measurements, especially for front projectors, are highly affected by reflected light; they are also affected by the quality of the optics and of course the type of display.  Really good ANSI CR’s are in the 300:1 range.  Most manufacturers list the on/off contrast ratio, very few list the ANSI measurement, which is actually closer to what you experience with real video.

Full on/off CR is just like it sounds.  The light and dark measurements are made with the display displaying a full 100 IRE field and a 0 IRE field.  The ratio is then 100IRE measurement divided by the 0 IRE measurements.   Measurements must be made in a completely dark room.  Very good measurements are 2000:1 and above, CRT’s can hit 5000:1 or more.  Good LCD’s are 800:1, Good DLP’s are >1500:1.   Many single chip DLP’s have their CR measured with the “white segment” of the color wheel turned on.  This increases the 100 IRE measurements by a significant amount.  Most home theater users will turn the white segment off, and in fact many projectors turn it off automatically in video mode.  The white segment skews the gamma curve but provides higher output for presentations.

Should I use an equalizer in my home theater?

An equalizer can be a useful addition to a home theater system. It is not however, the first line of defense for achieving a flat response. Proper room design, speaker and listener positioning, and acoustic treatments should all be optimized first.

When applying an equalizer to a system, it is important to understand what equalization can and cannot fix. It cannot fix temporal distortion caused by early reflections; it cannot fill holes and gaps in system and room response. It can be used to selectively reduce peaks and resonance and to even the frequency response between channels.

Proper set up requires instrumentation, at least a real-time spectrum analyzer (RTA), a MLS or swept frequency test set that can show the temporal effects of the room response is even better. Any RTA used should have at least 1/6 octave resolution. Just because there is a slider to adjust for a given frequency, or a parametric channel available, it doesn’t mean it needs to be adjusted. There should be a good reason for applying equalization to that frequency band.

A key difference between a two-channel system and a home theater system is that home theater tends to be a more social activity, requiring that the “sweet spot” cover a large number of seats. The best set up of an equalizer for a home theater system should use frequency domain averaged responses from several representative locations in the room, with the equalizer set to maximize first the linearity and second the SPL of the average response.

Last update: 7/8/2011