Too much bass from TV optical output

[AA6U]

I'm hoping someone can enlighten me regarding too much bass coming out of the optical output of my Visio TV. I'm using the TV as the HDMI switch for all of my devices (cable box, Roku, FireTV, etc.). I then connect the optical output from the TV to a DAC and then to my McIntosh C32 preamp. The audio from all of the devices has too much bass. I can cut it using an equalizer and reduce 150Hz to make it sound normal, but this is not the best way to process quality audio.

My question is whether the TV us boosting the bass or whether all of devices boost the bass so it is simply being passed through the TV. The DAC is not at fault because it sounds great when used with the optical output of my computer. I was under the impression that the TV's optical output is not processed and is simply the digital signal coming in through the HDMI ports.

If the TV is at fault, I am assuming that using an external HDMI switching box with optical audio output would solve the problem.

Any thoughts?

 

[restorer-john]

Many TVs have a whole bunch of settings to do with exactly what comes out the optical out. I know mine does and it took me a while of fishing through menus to force it to output plain-Jane SPDIF 2.0 PCM 16/48.

It could be sending a kind of 2.1 SPDIF or 2.0+LFE.

Have a dig through the menus, particularly with the options on output jacks and audio settings. With mine, it took a strange combination for it to be able to send 2.0 out, even from HDMI and DD sources. Now it works, I don't mess with it.

 

[4-2-7]

Navigate into your "Sounds" on the TV and try some different effects settings.

They generally have names like Stadium, Hall, Natural, Movie.

 

[AA6U]

I have it set for "PCM" and the equalizer set for "Flat". All of the Dolby and Surround Sound settings are off. From what I've heard, those should be the correct settings to give me a neutral, flat frequency response, but I still get the bass boost.

 

[4-2-7]

Are you bi-passing the C32 tone controls?

What about the C32 Expander and Level controls?

By using the EXPANDER controls in conjunction with the EQUALIZER FREQUENCY controls, the C 32 may be used to de-emphasize and decompress disc and tape program material.

What about the Hi & Lo Filter switches?

HF and LF Filters The HF and LF filters are selected by pushbutton switches in a manner electrically similar to the program EQUALIZERS and are pushbutton switch selected. The HF filter attenuates all frequencies above 5 kHz, reaching a rate of 12 dB per octave, at 7 kHz (at which point attenuation is 3 dB below the 5 kHz level). The LF filter attenuates all frequencies below 50 Hz, at a rate of 12 dB per octave. All program EQUALIZERS and HF/LF filters are bypassed when the EQ OUT pushbutton switch is depressed. The EQ OUT switch also removes subsonic and supersonic filters below 20 Hz and above 20,000 Hz, exten

 

[AA6U]

With the C32 equalizer out, it is basically the same as with it in and the tone controls at mid level. Expander doesn't help. To be sure it's not the C32, I tried a different preamp and amp and experienced the same bass problem, so it is not the C32. I can get the C32 to sound good only if I decrease the 150Hz and 500Hz tone controls. For the other preamp, I used an equalizer and decreased those frequencies to get it to sound good.

 

[Velocityboat]

It could possibly be room acoustics and bass modes. Moving listening position or moving speakers is a non equalizer cure.

If you want to bypass TV audio splitter buy one of theses to split of your digital sound from HDMI to DAC. There is a non 4k version slightly cheaper.

https://www.altex.com/Calrad-4K-HDR-HDMI-AUDIO-EXTRACTOR-TOSLINK-SPDIF-COAXIAL-L-R-Analog

 

[AA6U]

If I totally bypass the TV and feed the amp directly from a CD player, the extra bass is gone. It only happens when the audio is passed through the TV. I tried to change audio settings on the TV but couldn't find anything that cured the problem. The splitter you referenced looks good, except that I would need an HDMI switch also because I have to extract the audio before the HDMI TV input from about five different sources. Right now I'm using the TV as the HDMI switch.

 

[Pyrrho]

I have it set for "PCM" and the equalizer set for "Flat". All of the Dolby and Surround Sound settings are off. From what I've heard, those should be the correct settings to give me a neutral, flat frequency response, but I still get the bass boost.

Whether those settings would give a flat output or not depends on whether the TV has other audio processing. From reading all of your posts (through post 8), it seems that the TV is boosting the bass (either due to a setting, or poor design or malfunction). However, using your CD player as a "test" does not prove this, as that was not run through the TV (unless your CD player has an HDMI output). If you have a BD or DVD player (or computer with CD drive) with HDMI, when you play a CD in it, does it have too much bass when run through the TV, but not when using the optical or coaxial digital output connected to your DAC or analog output connected directly to the preamp?

If you have another TV with HDMI inputs, or a receiver or preamp with HDMI inputs, you could substitute that for the TV and see if that corrects the problem. If it does, then you will know that it is certainly the TV (though that will not tell you if it is a malfunction or a setting in the TV).

Without knowing the exact model of TV, no one can look in the manual online to look for possible settings that could cause your problem. You could also try contacting Vizio, though I recommend spending some quality time reading the manual for your TV first.

But, in general, there are often settings like "night time" mode and "dialog enhancement" modes that process audio. A lot of TVs these days have many audio processing functions.

 

[AA6U]

I did a test by running the CD player output into the external audio input of the cablebox and then outputting the cablebox HDMI into the TV HDMI input then through the DAC into the preamp/amp and it had too much bass. Then I tested the preamp/amp by running the CD player output directly into the preamp (analog) and it sounded correct with no enhanced bass. It's not the DAC because I have used it with my computer optical output and it sounds great. I have the TV audio mode set to flat and turned off all processing. The TV is a Vizio XVT553SV. Unfortunately, I do not have another TV to compare it with.

 

[Pyrrho]

Do you have SRS TruVolume turned off? See page 40 of the manual:

http://cdn.vizio.com/manuals/kb/legacy/xvt473svmanual.pdf

Also, look at page 41. It appears that the EQ settings are separate from the "Audio Mode" settings (where you have selected "flat"; see page 40). So go into the EQ settings and make sure that the EQ settings do not boost the bass, in both the "basic" and "advanced" settings.

If that does not work, you may wish to try using the analog line level outputs on the TV.

 

[AA6U]

Yes to all of those suggestions. That's why I am frustrated.

I originally used the TV line level outputs into the preamp, but the TV has a low quality audio output so the sound was poor and it still had too much bass. That's why I went with the DAC which gave me much better quality audio, but still has too much bass.

I am considering buying an external HDMI switch with an audio extractor then using the optical output from that into the DAC/preamp. I just want to make sure that the stations/channels are not boosting the bass to compensate for small speakers in most TVs which would make buying the HDMI switch pointless.

 

[Pyrrho]

I use a receiver for hooking things up (both HDMI and other), and there is no excessive bass from any source. So, I can tell you that Roku and TV stations are not generally boosting the bass excessively.

You are not making me want to buy a Vizio TV. I would find your sound issue maddening, too. You might try sending an email to tech support (p. 57), but I suspect that they will not be able to help you. Still, it is probably worth trying.

One last suggestion, before buying anything, and that is try resetting everything to the factory settings (p. 51), and then resetting things to how you like it. Before doing that, you might want to write down how you have everything setup, as this isn't a fun option. But it is possible that it might work.

If you ever do get it working right, it would be good for you to post how you do it, as it may be of help to someone else. But I am wondering if Vizio incompetently made your TV. If so, you will never get it to work right, and will need to buy something else to deal with the audio from your HDMI sources. I'm sorry; I wish I had something more to say, but nothing else comes to mind at present.

 

[Pyrrho]

I went away and took a bath, not thinking about your problem, and a solution occurred to me. It is so simple that I almost wonder why I did not think of it earlier. Simply turn down the bass in your TV's EQ. Not down to where it tells you it is flat; down where it tells you that you have reduced the bass. Turn it down until it sounds right. Or as right as you can get it. If you can play a CD both through the TV and bypass the TV (perhaps using different outputs on your player), that could be useful for getting the bass right.

Of course, this is not a "proper" fix (which is why I did not think of it earlier), but it should work reasonably well, given what you have said about being able to adjust your Mac's EQ to make it sound okay. I would still try the other ideas above, but if all else fails, I would do this. It costs you nothing but your time and trouble to try this option.

(By the way, Einstein supposedly liked thinking while taking a bath, too. So, when you have a problem, you can try using some of your wife's nice smelling bath salt or bubble bath, and relax in a hot bath, letting your mind wander. If you don't have a wife, you will need to buy some of these things for yourself. Happy thinking!)