Home Theater audio systems are sufficiently complicated it can be quite daunting when something goes wrong. Where do you begin? Has something failed? Did I accidentally screw up a setting. Is it SUPPOSED to sound this way?
In this post we'll discuss some logical steps towards diagnosing audio failures.
The first step is realizing you even HAVE a failure! Of course if one or more of your speakers simply isn't producing audio at all, that's pretty obvious. But what if a speaker IS producing audio, but that audio isn't right?
"Listener Bias" is your challenge here. The brain hears what it expects to hear. Which means things can go quite a bit "wrong" before it gets so bad you can't "not hear" it!
In the discussion threads on AVSForum.com for Anthem branded AVRs and Preamp-Processors there's even a name for this: It's called "Richard's Syndrome" for the first poster to exhibit it. These Anthem products offer a type of digital Room Correction processing marketed as Anthem Room Correction, or ARC. One of the features of ARC is it can display charts of raw (uncorrected) audio measurements from your speakers. "Richard" had posted asking for help because his ARC charts were showing one of his two Front speakers had NO bass output whatsoever!
His assumption, of course, was he MUST be using ARC incorrectly -- somehow -- because his speakers sounded just fine to him! In reality, the speaker in question had failed. Its bass audio driver element (woofer) was toast, and likely had been for some time. His brain just "didn't want to hear" that!
Thus Richard Syndrome: The shocking discovery one of those great sounding speakers you've been thoroughly enjoying up to now actually failed some time ago!
If you don't happen to have a tool like those ARC charts handy to point out the obvious, how DO you get around your brain's own, Listener Bias? The trick is to get out of the brain's comfort zone. I.e., listen to unusual stuff and/or in an usual way.
As for "unusual stuff", check basic functionality of your speakers using test tracks from a calibration disc, instead of music or movie content you already know too well. For example, see the test discs listed in my post on Calibration Discs.
As for "unusual way", use the Ear Test. Speakers produce audio by combining output from a set of distinct, "driver" elements. A typical speaker might have a bass driver (often called the woofer), a mid-range driver, and high frequency driver (often called the tweeter). If your speaker has an easily removable front grill, removing the grill will reveal the different drivers. Larger speakers may even have multiple drivers of each type.
When you listen from your normal seating position, the audio from the different driver elements blends together, making it much harder to hear problems in any one driver. Partly this is because the drivers overlap in the audio frequencies they produce.
But if you get right up close to the speaker and put your ear next to each driver in turn, you can hear the output of that one driver quite distinctly.
This is the Ear Test: Checking each driver in turn on your speaker, with your ear right up next to it, while listening for problems.
Even if your speaker grill is not easily removable, by moving your ear around right next to the grill, you will soon learn the location of each driver behind that grill. Be sure to adjust Volume so you can hear each driver clearly in this fashion, but without the sound being so loud it is too painful or tiring to listen attentively.
Some problems will be obvious, such as if a particular driver is producing no audio at all. Or a "torn cone" -- a common type of mechanical failure -- will produce a buzzing, or even flapping, sound which is clearly wrong.
For the most sensitive test, play the same content into a pair of matched speakers and compare between them via Ear Test -- driver by driver -- listening for differences. That is, move back and forth between the two speakers, putting your ear up close to the matching drivers on each of them in turn. If you have a Monaural audio track handy, you can use it for this. Some AVRs and Sound Processors also offer an All Speakers Mono audio output mode -- sometimes touted as useful for parties -- which down-mixes whatever you are playing into a single, output speaker channel which is then sent to all the speakers.
USUALLY, when you discover a problem with a speaker driver like this, the cause is a failure in the speaker itself. Either the driver in question has failed or the "crossover" circuit inside the speaker has failed.
TECHNICAL NOTE: In my previous post on Choosing a Crossover Frequency I discussed setting up Crossover processing in your Home Theater electronics to steer bass from your main speaker channels to your Subwoofer, which of course is a speaker specialized for high quality bass reproduction. But each of your main speakers also has its own, built-in Crossover electronics -- a fundamental part of the design of all good speakers -- which separates the audio frequencies sent to each of the driver elements in the speaker. Typically the Crossover built into the speaker for this is not adjustable by you. It has been preset as part of the design of the speaker. But as with all electronics, the Crossover circuit inside your speaker is also subject to failure.
However, before you crate up the speaker and call the freight company to haul it off for service, there are some other things you should check!
First, most high end speakers, and even many affordable speakers, have multiple input jacks for the audio coming into them. A common arrangement would be to have one pair of jacks for bass, and another for mid-range and high frequencies. The idea is, some folks will want to use more than one amplifier to drive their speakers, and this allows them to dedicate one amplifier for bass and another for mid and high frequencies -- separately wired to the separate input jacks on the speaker. I.e., you'd have more than one pair of speaker wires going to each speaker!
But for most folks, this is overkill. They use one amp, and have just one pair of speaker wires going to each speaker. For THOSE folks the speakers come with "buss bar interconnects" which are nothing more complicated than a pair of electrical connection straps attached directly BETWEEN those two sets of input jacks. So you can attach your pair of speaker wires to either set of input jacks, and the buss strap makes sure the same signal is also going into the other set.
If you followed that description, it should be obvious what happens if the buss straps are missing, or loose, and thus not making proper electrical contact, at both ends, to the two separate sets of input jacks: You lose audio either to just the bass or to just the mid and high frequencies!
So if you have lost audio from a driver element, start by checking any buss straps between separate input pairs on that speaker are properly in place, and tightly attached.
The next step is proving the problem really IS in the speaker in question, and not in some other part of your system -- i.e., your electronics or settings. It turns out this is trivially easy to do -- indeed, patently obvious once the method has been pointed out -- but a surprising number of folks don't figure this out on their own. To wit: Test by swapping cables!
Cable Swapping Test: Pick another speaker that's working and swap the speaker wires -- at the end connected to that working speaker -- with the speaker wires connected to the speaker having the problem. That is, detach the wires from where they connect at the back of both of those speakers and re-connect them to the opposite speaker. If the problem REMAINS in the original speaker, then the fault is in THAT speaker. If the problem SHIFTS to the speaker which had been working, then the fault is EARLIER in your audio signal path -- perhaps cabling, perhaps, electronics, perhaps settings. But the speakers themselves are exonerated!
CAUTION: It is easy to get sloppy when facing the annoyance of failure in your gear. This is the time to take a step back, take a deep breath, and THINK about what you are doing. Double-check each step. Speaker wires carry enough current that a shorted connection can damage your power amp! Speaker wires are often multi-stranded, and it just takes one hair of wire out of place, touching the wrong thing, to produce a short. When swapping wires, turn OFF your power amp (or AVR if you do not have a separate power amp). To be even safer, UNPLUG it from wall power. And double check your connections BEFORE you power back up again. Moving wires between speakers like this can also shift the cables at the end which connects to the amp as well. So check THAT end TOO to make sure the connection there remains good -- and clean of shorts -- before you power up.
PRACTICAL NOTE: If you wiring is channeled in some way which makes it hard to swap connections -- for example, if you have in-wall wiring -- it is often simpler to buy separate speaker wire cables to make a new, direct run, outside the wall, between your power amp and the two speakers for testing. First verify the problem still exists with the new, test cables, then swap the ends at the back of each speaker, as described, to see if the problem remains in the same speaker or not. These test cables need not be exotic, expensive cables.
If the problem remains in the original speaker, then that speaker needs service.
But if the problem MOVES to the other speaker when you do the Cable Swap, then you know the fault is someplace earlier in the audio signal path.
So, umm, NOW what?
Simple! Move back down the audio signal path eliminating each device in turn until you find the culprit!
So suppose you have a Source device, a pre-amp, a power-amp, and your speakers -- with cables in between them. You've just eliminated the speaker as the problem. Now restore the speaker ends of the speaker wires to their original speakers. Next, go to the outputs of your power amp and swap the speaker wires at the outputs. This is just another Cable Swap Test, but this time at the outputs of the power amp. If the problem remains in the SAME speaker then the cable leading from the power amp to that speaker is faulty! If not, then you've eliminated the speaker cable as the culprit.
Next put those speaker cables back to their original outputs from the power amp. Then swap the INPUT cables from the preamp to the power amp at the input sockets of the power amp. Again, this is just another Cable Swap Test. If the problem remains in the SAME speaker then that channel of the power amp is faulty! If not, then you've eliminated the power amp as the culprit.
Next swap at the outputs of the preamp. If the problem remains in the SAME speaker, then the cable between the preamp and the power amp is faulty. If not, then the cable is exonerated.
Next swap at the inputs of the preamp. If the problem remains in the SAME speaker, then that channel through the preamp is faulty. (It may have an electrical fault, or it may have an incorrect setting.) If not, then the preamp is exonerated.
Next swap at the outputs of the source device to check the cables to the preamp. If the cables are good, then the problem MUST be in the source device.
If you were following along in that description, some questions must have jumped into your head. First, or course, if you are using an AVR then your "preamp" and "power amp" are actually combined in one box, so you can't separately test them.
But second, if you are using digital audio cabling (such as HDMI) to your AVR, how can you do the swap? The answer is, you can't (in any practical way). If you've gotten back to that point in the cable swap testing, and still don't have the culprit identified, your best bet is to see if you can reproduce the problem using a Stereo ANALOG audio cable pair between your source device and your AVR. That's a connection you can swap (Left for Right).
(Another step is to try a different HDMI Input into the AVR to see if the problem is specific to one Input.)
If you have isolated the problem to one electronic device in your setup, the next question is figuring out whether that device has an electronic failure or has simply been set incorrectly. Usually the easiest step at this stage would be to do a Factory Reset on that piece of electronics to revert all of its settings back to "normal". If the problem still exists, then odds are you are dealing with an electronics fault.
TECHNICAL NOTE: A variant on audio failures is the complaint that audio is coming from some DIFFERENT speaker than you expected. Such issues are almost always due to the way your electronics try to match multi-channel audio tracks to the speakers you actually have configured. For basics, see my post on Understanding Audio Down-mix and Surround Sound Processing. For example, if you play a 5.1 channel audio track into a 7.1 channel speaker configuration, your AVR may produce audio for the Rear Surround speakers. If the audio in the Side Surround channels of that 5.1 track is "correlated" -- meaning, essentially, that it is Mono audio sent to both of those Side speakers -- then the audio is treated as if it were for a single, Rear speaker behind the listeners. Meaning you get ALL the audio sent to the Rear Surrounds of your 7.1 speaker setup and NONE in the Side Surrounds! Multi-channel tracks authored using DTS can take this even further. For example, if you play a 7.1 channel track into a 5.1 speaker configuration, some of the Side Surround content will appear in the FRONT speakers! Why? Because the standard speaker layout for a 7.1 track is that the Side Surround speakers are even with the seating. Bu the standard speaker layout for a 5.1 speaker configuration has the Side Surround speakers somewhat BEHIND the seating. So the Side content of the 7.1 track -- as mixed by the Studio -- is actually positioned in front of the Side speakers in a 5.1 speaker configuration! Processing for DTS tracks "corrects" for this by making "phantom 7.1 Side speakers" -- i.e., by putting out audio mostly to the Side Surrounds of the 5.1 speakers, but also a little to the Front speaker on the same side to produce a blend that's somewhat forward of those Side Surround 5.1 speakers.
Before finishing up this post, let me cover two special cases of "speaker failure" which are quite common.
First is the complaint, "I've lost ALL audio (not just one driver) from a speaker or a set of speakers, but other speakers are working fine!"
Indeed, you may not even have noticed that MORE than one of your speakers has failed. For example what I'm about to describe is most often first spotted as the CENTER speaker has failed -- made obvious because of the lack of dialog in movies.
Usually a complete loss of audio in one or more speakers is due to an amp failure. But sometimes this amp failure is no more complicated than the the amp in question has simply not been turned on!
How can that happen? Suppose you have a 7.1 speaker configuration. To get the best possible audio to your Front speakers, you are using a high quality Stereo amp for just those two speakers. The other 5 speakers (Center, the Side Surrounds, and the Rear Surrounds) are being handled by a separate, less exotic, Home Theater, 5-channel amp.
Well if you play a movie and the Stereo amp is powered -- but the 5-channel amp is NOT powered -- the first thing you are going to notice is the Center speaker is dead. No dialog!
So if you've lost audio to one or more speakers, check that the power amp feeding into those speakers is actually live. If you have the power amp configured to turn on automatically -- via a "trigger wire" connection for example -- make sure that connection is still properly in place.
Second is the complaint, "I hear an echo!"
This is most commonly reported from folks who have a TV with built-in speakers, but who are actually using their separate set of Home Theater speakers for audio.
The problem is, audio is ALSO getting to the speakers built into their TV! The echo happens because the audio delay timing (the lip-sync adjustment) is different for the speakers in the TV and for the Home Theater speakers.
Typically the audio is getting into the TV via the HDMI cable feeding video to the TV. If you can not mute audio on that HDMI path to the TV, the cure would be, of course, to mute the speakers in the TV itself (or lower the TV Volume to 0 to do the same thing).
Just remember, when you DO encounter an apparent audio failure, there's usually a fairly simple, logical approach to isolating the culprit and figuring out which piece of your gear -- if ANY -- needs service.