A Review By: Alphonso Soosay
Latest Home Theater Surround Sound AV Receivers allows you to gain access to connected components, such as a Blu-ray, DVD player, Set Top Box, Video game console, CD player etc. You can also tune into radio stations via the receiver’s built-in tuner. For internet connection models that will connect to a home network, this includes Internet radio stations.
A Home Theater receiver combines three components in one, a preamplifier, a tuner, and built-in amplifier. The preamp lets you select which source you’d like to listen to or watch. With today’s receivers, that can mean anything from over-the-air radio broadcasts to the smartphone in your pocket. The tuner section just let you enjoy over-the-air AM or FM broadcasts. Some latest receivers no longer include an AM tuner, but many have added more modern music sources such as HD Radio™, satellite radio, and Internet radio. The built-in amplifiers job is to create a spontaneous, surround excitement, and engaging soundtrack to match the on-screen video. You will require a receiver with enough power to satisfy the speakers of your choice and to really rock your home theater room with excitement.
These days digital surround sound Audio Visual receivers have come a long way from the stereo days; in fact, in the ongoing production of ever higher quality multi-channel surround formats, simple stereo receivers have become precisely uncommon items. For most of us who still recall the days when 2 channels stereo was the best you could hope for. The move to 7.2 channel AV receivers is something of a sense of balance blessing. Multichannel surround sound will sound wonderful when watching movies and live concerts, but choosing and operating a 5.1 or 7.1-channel AV receiver is broadly much more complex than 2-channel procedure.
I am a Stereo and Surround Sound enthusiast; let it be for HD movie Soundtracks, Musical Concerts, Jazz, Pop, Rock, Country or Classical recordings. On the other hand, for consumers who do not want to get involved with five to seven speakers plus a sub-woofer, a simple stereo receiver is all they need. But let me make it obvious that the latest Home Theater make excellent stereo receivers with robust amplifiers that will drive even 4-ohm speakers like Denon, Harman/Kardon, Axiom digital amplifier and other popular brands.
Surround Sound Receiver: serves as a command center for either a basic audio system (a stereo receiver) or as an intricate audio video routing, switching, surround decoding and amplification center for a multi-source audio-video system (a 7.1 channel surround AV receiver). In both cases, the receiver will contain an AM-FM radio tuner (whether you like it or not) and either two internal amplifiers (stereo) or, most commonly, seven amplifiers, for 7.1-channel surround sound. Now that Dolby Digital 5.1 surround sound has become the standard for HDTV broadcasts and the vast majority of DVD and Blu-ray movie soundtracks, it makes sense to get an AV surround sound receiver, even if you just use it in stereo for a time. The increased realism of surround sound is very seductive, not just for movie watching but also for most categories of music listening. It is, after all the way we hear in real life, with sounds coming at us from every direction, and it makes acoustical sense to reproduce it that way. Moreover, a basic Audio Visual receiver costs little more than a stereo receiver and gets you a lot more versatility and listening options.
Although some new Audio Visual receivers have connections for internet radio surfing and many are XM/Sirius satellite radio ready, a clever shopper must still consider basic output power for a given room and listening taste before going on to the more glamorous features. Together with this is the guide to some of the most important questions you need to address in finding an Audio Visual receiver that will run into your requirements and financial plan.
Speaker “Power” requirements: It’s the duty of a Audio Visual receiver’s to amplify the low incoming audio signals from Blu-ray, DVD, set top box and others to a level where it will drive loudspeakers to flawless, reasonably high volume levels in most typical family rooms and home theaters without audible distortion.
The first thing to look for is the receiver’s rated per-channel output power from an 8 to 4-ohm load. Most common domestic speakers are either 8 ohms or 6 ohms impedance, which are essentially identical for purposes of power output.
Methods to determine how much power an AV receiver truly generates is to separately measure the total watts produced by each channel, or to drive 5 channels simultaneously and measure the output of each. Cheaper brands don’t withstand that sort of stress and immediately shuts down when heat builds up current limiting problem. Popular brands manage it quite well, which points to a good, robust power supply section in the receiver. Bench tests of Home Theater receivers by Sound&Vision magazine regularly do a 5 & 7 channels driven test and, if you read the fine print in the test results or online, it will state how much power the receiver produces and whether or not the receiver shut down because of overheating or current limiting. In a perfect world, every manufacturer would state the power output of Home Theater receivers with “all channels driven,” either five or seven, into 8-ohm loads, over the full musical range. The power output will often be significantly less than with one or two channels driven, but if you find all channels driven specification or measurement, take it as a positive sign of robust amplifier design. If you are thinking about getting a pair of 4-ohm rated speakers like the Axiom’s M80 for your front main channels, check the Sound&Vision test reports for the AV receiver’s output results into 4-ohm loads. Certain brands will not drive 4-ohm speakers without overheating or shutting down. Others, such as Denon, NAD, Yamaha, Onkyo, Sony and Harman/Kardon have no trouble with 4-ohm impedance’s. Please double check the models you are purchasing for 4 ohms speaker use. I personally like 4 ohms speakers as they are so silent by themselves.
To look out for is continuous power output with two channels driven into an 8-ohm load, over the full audio range of 20 Hz to 20 kHz (more often you will see the power output rated at a single frequency, 1 kHz) with total harmonic distortion (THD) of less than 1%, ideally 0.7% or lower. Distortion at that level is generally conceded to be inaudible with musical programming or soundtracks. Keep a close eye on the THD (distortion) ratings. Some manufacturers play fast and loose with power ratings, even specifying some packaged home theater in a box (HTIB) electronics at distortion levels as high as 10%, which will not only be audible but total unpleasant sounding.
In what way “Amplifier Power” is Sufficient? To cover most home size theater rooms (Example: 6m x 4m), generally people will be quite happy with AV receivers rated at between 80 and 140 RMS watts per channel, with two channels driven. Although many Home Theater receivers will deliver far less than that when all channels are driven simultaneously, it’s not a critical drawback. Even with the greatest action pack movie soundtracks, it would be extremely rare to ever find a Home Theater receiver having to produce simultaneous output of 80 watts or 140 watts into each of its 5 or 7 channels. Typically, the surround channels demand far less power output (about 25 to 50 watts) than do the main left, center, and right channels, which carry the bulk of the acoustical output demands.
Inputs and Outputs: Home Theater Audio Visual receiver performs a source selection function, allowing you to choose which components (Blu-ray, DVD, Set-Top Box, TV, CD’s, DAT, iPod and MP3) to listen to and watch, so keep in mind how many audio/video sources you may want to connect now and in the future. That may also include an aging VCR for all those older videotapes or perhaps even a turntable (that input is called Phono, and note that only some AV receivers have it) for that old vinyl collection you can’t quite bring yourself to unload.
Every Home Theater receiver should have inputs for the full range of video connectors from HDMI, composite, S-video, and component video. With increasing price, the number and variety of inputs and outputs, especially HDMI, increases. The over $1,200/- models typically feature two, three or more HDMI inputs, and necessary of analogue and digital inputs and outputs, both optical and coaxial.
Entry level Home Theater AV receivers may offer only simple HDMI switching of connected components but you will want to make sure that whichever AV receiver you choose, the HDMI “version” is compatible with your HDTV input and with any upcoming purchase of HDMI-equipped components such as a Blu-ray player or gaming system. The latest HDMI version is 1.4a for 3D use, but earlier versions will carry many of the high-resolution audio formats.
At any time if you foresee getting a separate power amplifier with much bigger power output in the future, then make sure that your AV receiver has “pre-outs” (preamplifier output jacks) for multichannel.
Multichannel Surround Sound Decoding: With superior installations, your Home Theater AV receiver will do much of the work of “decoding” the various new and older surround sounds formats. There are now ten surround formats, Dolby Digital 5.1 being the standard of HDTV broadcasts and standard DVDs. The ten formats are: Dolby Digital (5.1), Dolby Digital EX, Dolby Digital Plus, Dolby TrueHD, DTS, DTS-ES, DTS-HD, DTS-HD Master Audio, Dolby Pro Logic II, Dolby Pro Logic II x. Additionally, you will find Logic7 on Harman/Kardon and Lexicon models. Classical music enthusiast will appreciate the extra ambiance, depth and expanded sound-stage that Logic7 often imparts to good classical stereo recordings. Logic7 is comparable to Dolby Pro Logic II(x) or DTS Neo: 6, all of which will take a 2-channel stereo source and synthesize center and surround channels to approximate 7.1-channel playback.
Commonly known “important” surround formats on inexpensive AV receivers are Dolby Digital and Dolby Pro Logic-ii x, now almost universal on even entry-level models. You will also find various DTS codecs comparable to the Dolby Digital variations, which most Home Theater enthusiasts prefer DTS because to some extent it increases deep bass effects. If you want to have the latest high-resolution multi-channel audio formats, Dolby TrueHD, DTS-HD (Master Audio) and Dolby Digital Plus common to Blu-ray high-definition discs, you will be looking at Home Theater AV receivers in the upper price range. However, as Blu-ray and its associated hi-resolution soundtracks become more common, prices will fall.
Budget Home Theater AV receiver lacking these capabilities it does not mean that you cannot hear the latest soundtrack formats from a Blu-ray player. As long as any AV receiver has a multi-channel (usually eight) analogue input set, then a Blu-ray player will do the decoding of Dolby TrueHD, DTS Master Audio or Dolby Digital Plus, and route the signals to the Blu-ray player’s analogue 6 or 8-channel outputs. It just means using more audio cables for its connection, with either six or eight analogue RCA cables between the Blu-ray player and your Home Theater AV receiver’s multi-channel input set.
On-Screen Display: Make sure the AV receiver has a readable on-screen display so you can navigate the receiver’s settings during setup and calibration. Most AV receivers will have on-screen options for component-video outputs, but typically only more expensive models offer an on-screen display with the HDMI outputs.
Auto-Setup and Calibration: Latest inexpensive Home Theatre AV receivers now have some type of auto-setup mode, with many including a supplied microphone and auto-calibration/equalization circuit (Audyssey is very popular) that claims to adjust the frequency response of the system’s speakers to match the room’s acoustic characteristics. While the auto-setup modes are initially useful for first-timers, they are still inclined to errors, sometimes setting speakers that are small to “Large” and making errors in speaker level settings of 4 dB or more. I would recommend that you do a manual check using a sound-level meter with a pink-noise signal on your Home Theater system.
Check the Remote Control: Remote control design is all over the map, and you often find a really desirable Home Theater AV receiver with an annoying remote control that has illegible markings, lacks back-lighting or uses tiny buttons all the same size. Most people will get used to almost any remote, but remotes with larger, different-shaped buttons, back-lighting, and easily readable markings go a long way to making a remote control easy to use.
Video Processing: Most up-to-date HDTV set will automatically do its own video processing, “scaling,” De-interlacing and trans-coding (convert) incoming video signals in order that they conform to your set’s specific fixed-pixel array (the latter is common to all Plasma, LCD, and DLP displays). Many Home Theater AV receivers also contain video processors that will perform similar functions. The question remains as to which unit your Home Theater AV receiver or DVD player or the HDTV does a better job. It’s generally agreed that there should only be one conversion take place for maximum picture quality; adding more than one may degrade the video image and add various visible processing artifacts. In any case, be sure to set your HD cable TV converter box or satellite receiver to output video at the native resolution of your HDTV display (720p or 1080i). If you have a 1080p display, try setting the cable box to either 720p or 1080i and see which produces the better picture.
The three operative terms that define up-conversion are:
- “Trans-coding,” which is converting one signal format like S-video to another, say component video.
- “De-interlacing,” converts an interlaced video signal (480i or 1080i) to progressive-scan, e.g. 480i to 480p or 1080i to 1080p.
- “Scaling,” alters the video signal from one resolution to another, like going from 480p to 720p.
A Home Theater AV receiver is the key to truly immersive, Movie Theater at your own home. In addition to providing impressively detailed surround sound, today’s receivers act as a connection hub for a huge variety of audio/video sources. This article will give you the basics of Home Theater receivers, and gives you the knowledge for your Home Theater requirements.
Alphonso Soosay / Home Theater Consultant