Home theater question

[wdfifteen]

I've had a surround sound home theater set-up for 6 years that has worked OK until recently. Now the sound from every speaker is slightly garbled, like the people talking have something in their throats. Sometimes the distortion is so slight you can barely hear it, sometimes it's so annoying we just turn the damn thing off. Our system has cable, dvd, and Apple TV inputs and the sound problem is the same on all of them. This system runs the sound&picture from the amp to the TV via HDMI cable and then the sound comes back to the amp via an optical cable (why do they do that?). We never operate it at high volumes, almost always around 25% and never more than 50%. Jiggling cable connections doesn't help. Any idea what the problem could be? I've googled the question and other people have the same problem, but no one seems to have a definitive answer.

[Miguel Antonett]

I believe that gurgulling/garbled/deep hole effect sound from a surround system is a frequency/signal thing more than hardware. I'd call the cable people to assist you troubleshooting. M2c

[stomachmonkey]

Originally Posted by Miguel Antonett

I believe that gurgulling/garbled/deep hole effect sound from a surround system is a frequency/signal thing more than hardware. I'd call the cable people to assist you troubleshooting. M2c

My first thought but he gets it from all sources.

Not clear why sound is routed through the TV.

That does not make sense.

Amp should output direct to speakers from the various components inputs.

I don't get the return optical.

[Miguel Antonett]

^^^+1. Yeah, there appears to be too much cabling back and forth... I'd disconnect the whole thing and recable it leaner... call the cable guy if you're marginal with that stuff.

[LeeH]

Voices shouldn't be coming from all speakers. Check your surround sound mode. Voices should be concentrated in the center channel. Other speakers should mostly be music and sound effects.

Same issue with headphones? Some older amps couldn't pull the audio signal from hdmi so the audio is run separately.

Do you get the same results from sources?

[stomachmonkey]

Originally Posted by LeeH

Voices shouldn't be coming from all speakers. Check your surround sound mode. Voices should be concentrated in the center channel. Other speakers should mostly be music and sound effects.

Same issue with headphones? Some older amps couldn't pull the audio signal from hdmi so the audio is run separately.

Do you get the same results from sources?

Yeah but he's got HDMI feeding the TV and Optical back to the amp.

Meaning the source for the TV's audio to feed the amp is the amp.

[Cajundaddy]

Process of elimination. Hook up your DVD sound direct and see if it clears up. If it does, hook the rest up direct. The re-route through the TV is probably a workaround to simplify remote control input. I have all sound direct from each component but I also have 4 remotes.

[wdfifteen]

Originally Posted by stomachmonkey

My first thought but he gets it from all sources.

Not clear why sound is routed through the TV.

My understanding is it has something to do with keeping the sound in sync with the picture, but I don't know. Non-TV audio inputs (radio and iPod) do not route through the TV.

[Cajundaddy]

If other inputs run direct and all suffer this problem, it is the amp output section. Failed DSP or possibly failed output transformer. Try turning off the DSP and just run straight stereo. Is it still a problem? If you had carpet installed recently or any speaker cable re-routes, use a VOM and check the impedance on each speaker wire from the amp. I had a carpet installer run one of my speaker wires over a carpet spike and over time it shorted the speaker wire and smoked a fine amplifier I had owned for 20 years.

[wdfifteen]

Originally Posted by Cajundaddy

If other inputs run direct and all suffer this problem, it is the amp output section. Failed DSP or possibly failed output transformer. Try turning off the DSP and just run straight stereo. Is it still a problem?

DSP = the Dolby system??

I just realized I have not tested the system by listening to the radio. That would eliminate all possibility of cabling issues, as the radio receiver is integral to the amp.

[Cajundaddy]

DSP is the Digital Signal Processor that distributes sound to your different amp channels based on it's setting. When you switch from adventure to sports to disco to dolby surround you are using the DSP.

[flipper35]

Do you have a cable box or is it connected to your TV directly? If nothing other than the receiver is connected to the TV I would remove the optical cable. I don't see how it is going into the receiver to the TV and back to the receiver speakers. It should be playing through the native connection of the device unless the TV is through a monitor channel or something. This would eliminate the TV as the issue as well.

Does the sound come through normal on just the TV speakers?

We have an optical from our TV to the HT system, but that is so we can use the HT system for over the air shows in Dolby and the sound originates at the TV. Everything else goes through the HT system.

[LeeH]

What's the brand/model of the amp?

[wdfifteen]

Originally Posted by Cajundaddy

DSP is the Digital Signal Processor that distributes sound to your different amp channels based on it's setting. When you switch from adventure to sports to disco to dolby surround you are using the DSP.

Gotcha. I usually keep it set to Disco.

Flipper, I have a cable box supplied by Time Warner. The cable box is connected to the HT amp via HDMI cable and the HT amp is connected to the TV via HDMI cable and an optical cable for sound. Disconnecting the optical cable kills the sound completely.

This is how it is wired, except for the Component wires they show I have optical.

[LeeH]

To me, it seems like there should be no need to have any sound coming back to the amp from the TV. The receiver should pull the audio from the HDMI cable. Some older receivers didn't do this, but from what I can tell, this one should.

The only reason I can imagine for having sound to the amp from the TV would be so you can pipe audio from OTA signals through the stereo.

[Z-man]

Most amps from that era have an HDMI for video that serves as 'pass through' which is why you need a separate digital optical cable to get sound to your speakers. Connect the optical out directly to the AMP - no need to run it through the TV. Also -check the fiber ends - clean them with a fiber optic cleaner (or alcohol swab).

Besides the cable box, how are your other components connected? HDMI & digital optical cable as well?

There is a flexible glass tube in your optical cable - but it can only bend so much. If your cable has been bent then the tube will crack and cause data packets to be dropped. But I can't imagine all of your optical cables going bad all at once...

-Z

[LeeH]

Originally Posted by Z-man

Most amps from that era have an HDMI for video that serves as 'pass through' which is why you need a separate digital optical cable to get sound to your speakers. Connect the optical out directly to the AMP - no need to run it through the TV. Also -check the fiber ends - clean them with a fiber optic cleaner (or alcohol swab).

Besides the cable box, how are your other components connected? HDMI & digital optical cable as well?

There is a flexible glass tube in your optical cable - but it can only bend so much. If your cable has been bent then the tube will crack and cause data packets to be dropped. But I can't imagine all of your optical cables going bad all at once...

-Z

I think if this receiver just passed the video through, the manual would direct the user to hook up digital audio directly from the source to the receiver. I pulled up the manual for this one and it shows connecting a DVD player only using HDMI.

I have an older Pioneer Elite that will switch the HDMI video signal, but not process the audio. The manual shows not only shows hooking up a separate audio connection, but has a warning that if you don't do this that you will get no sound.

I'd be looking in the receiver settings for some way to switch the audio to HDMI. The manual I found is only 5 pages long and lacks any details about the set up menus.

Do you have another HDMI cable you can try?

[flipper35]

The receiver may have the option to push the sound through a different input. For instance, and older computer using a DVI-HDMI converter would not pass sound through the HDMI cable so an alternate connection would be needed for sound in this case. It may be that your amp has the TV selected as the sound for all inputs. Does the TV output proper sound?

What brand and model is it?

[wdfifteen]

The more I study this, the more I think the circled connection is just a switchable pass through and the signal isn't intercepted by the amp at all.



That would make sense because the TV has to get signals from the DVD and the Apple TV too. When I select a source on the remote, the amp selects an input to connect to the TV. The sound and video are separated by the TV and the sound is sent to the amp via the optical cable, since sound is all it needs. The amp has four or five of these ports (you can see them to the left of the cable IN wire in the image above), while the TV only has one or two, so to hooking up all three inputs (cable, apple TV, and DVD) to the TV would be impossible.
I'm at work now and can't get the make and model of the amp. Sorry.

[wdfifteen]

I am getting together a diagnostic plan for when I get home.
First, switch the DSP around to see if that changes anything.
Then connect the TV sound OUT component port to the amp's component sound IN to eliminate the optical cable as the culprit.
If that doesn't work I'll connect the TV directly to the Cable or DVD or Apple TV to eliminate some cable connections and whatever is inside the amp that connects the Cable/DVD/Apple TV IN to the TV OUT.