Getting bass with stereo audio playback from HTPC

[singemagique]

I recently upgraded my 5.1 home theater system and have my HTPC feeding audio/video over HDMI to my AVR which then is connected to my TV via HDMI. Movies sound fantastic with Dolby TrueHD and DTS HD Master working beautifully. The problem I am having is getting an adequate bass response from my subwoofer when playing audio files from my HTPC. I will try to lay out my observations and things I have tried. Sorry for the long post but I hope it helps to explain my questions at the end of the post.

My setup is as follows:

HTPC:

ASRock A75M-ITX
AMD A6-3670K
G.Skill 4GB DDR3
Lite-On BluRay Drive
Windows 7

*HDMI Audio is set to 5.1 with full range speakers and all enhancements disabled. Both 'allow applications exclusive mode' and 'give exclusive mode priority' are checked in the advanced audio options.

5.1 Setup:

Pioneer VSX-919AHK Receiver
Polk Monitor 70s (Front)
Polk Monitor 30s (Rear)
Polk Monitor CS2 (Center)
Polk PSW10 (SW)

*All speakers are set to small with crossover at 80Hz.

I understand music files are 2 channel stereo audio with no independent .1 LFE channel, but I would still expect any audio signals falling below the crossover point would be sent to my subwoofer. At this point I am getting only a minute bass response even in bass heavy electronic music.

The most interesting aspect of all of this is that if I play the same music file from both my HTPC and from my iPod directly connected to my AVR, the iPod signal produces great bass. It is still just front L/R stereo, but the subwoofer is doing its job. Additionally if I play music through my Pandora One application on my HTPC I also get a great bass response and the LFE wave light illuminates. So I think I may be missing a setting some place or the computer is doing some pre-processing to my audio files.

Here are the things I have tried:

1) Switching the HTPC audio settings to 5.1 while unchecking full range speakers...No dice. Switching the HTPC to 2-channel stereo both with and without full range speakers..No dice. I chose to stick with the 5.1/Full range speakers because that is where Pandora One audio (what I listen to most often) sounds the best.

2) Changing the speaker settings on my AVR to Large (full range) with subwoofer overlap (PLUS). From what I understand from my AVR manual this sends the LFE to both the front and subwoofer...No improvement.

3) Changing the crossover. I have tried 50, 80, 100, 150Hz. There is definitely more sound coming from the subwoofer as I increase the crossover, but still the music files played from the HTPC do not compare to playing the same song from my iPod or even Pandora One.

4) Turning off Direct/Pure Direct pass through on the receiver. From what I understand these pass the audio stream through to the speakers with little to no enhancement. I didn't notice a big difference either way.

5) Changing default shared mode quality settings in HDMI advanced audio properties. I have tried 16bit/44,48,96kHz and 24bit/44,48,96kHz. I can't tell a difference with any of the settings.

Here are my questions:

1) When my HTPC is set to 5.1 audio (in the audio configuration) my AVR displays PCM unless I am playing an DD or DTS encoded stream at which time it displays the current encoding. Is the PCM display what I should expect when the HTPC is set to 5.1? Does this mean my PC is doing some sort of processing to my audio files?

2) When changing the default shared mode settings both 16bit and 24bit 192kHz settings causes garbled audio even though my AVR explicitly states in the manual that it supports 192kHz audio. Is this more evidence that my computer is doing something to the audio signal before it gets passed to my AVR? Why does the shared mode setting matter if the application running is given exclusive control, shouldn't the application stream whatever the source audio quality is directly to the AVR?

3) Pandora One in my current setup has a dedicated LFE signal (according to the lights on my receiver) and sound comes out of all 5 speakers plus the subwoofer. The AVR still displays PCM. To my knowledge Pandora One only streams 2-channel music. Why/how is the stream being processed to 5.1?

4) I have tried several settings on the receiver: Stereo, auto surround, etc. to no avail. Music file playback (WMA, MP3, FLAC) using three different softwares (WMP, VLC, PowerDVD) still don't give much if any of a subwoofer signal. There is a bit, but not nearly (probably less than 50%) of what I get when playing the file through an iPod (MP3) with no equalizer settings. Does anyone else have this problem? What can be done?


Thanks for reading!

 

[ssddx]

i may not be as familiar with audio lingo or speaker settings as some since i tend to focus on the practical side but i may be able to at least point you in the right direction.

i use a similar setup as you.
-pioneer vsx-60 receiver
-5.0 klipsch quintet iv
-450w klipsch sub
-pc, ipod, ps3 inputs.

i did not install soundcard drivers, use default windows sound settings (with avr as default device) and use default player settings typically. in some cases i use the electronica equalizer setting in music players. my avr settings are default with the exception of running speaker setup (satelite, 5.1). normally i run on auto but ocassionaly swap audio modes. my subwoofer knob is normally about 20-25%

i get around the same bass output as i do on the mp3 player. my mp3 player is always set to electronica on the equalizer for bass output.

1) the pc is set to use the receiver as the default audio device using default settings. the receiver is normally set to auto and i also get pulse channel modulation (PCM) on display or DTS/DD when playing surround sound. from the little reading i have done PCM is what you want for good quality sound.

2) not sure what you mean by shared mode. while your pc may export sound to the avr for processing sometimes soundcard drivers and windows/application sound settings can be a pain. for this reason i did not install my integrated soundcard drivers and have win/app audio settings to default usually.

3) the stream is still likely stereo but either the program, windows or avr is duplicating the sound to the rear speakers. i know one audio mode on my receiver does this... i thought it was called full range but i could very well be wrong.

4) what are your win/app equalizer settings? your avr sound mode could also affect this. soundcard software has also been known to throw a curveball into the mix.

-----

i think you are thinking along the right line. it sounds like a pc software setting to me as well.

 

[singemagique]

Thanks for the reply.

Since you didn't install any sound drivers does your receiver show up under Sound Devices in Windows? I assume you are outputting audio over HDMI?

My default device is the AMD HDMI Audio using AMD drivers which I believe were installed as part of the Catalyst software. I could try uninstalling the drivers and letting windows auto detect.

1) Good to know PCM is what I want!

2) The Shared Mode is under Playback Devices > Select Device and click Properties > Advanced Tab > Default Mode. I'm not sure if this makes any difference at all, but it was something I toyed with.

3) That is what I was thinking also, but it only does this for the Pandora One application and not other 2-channel audio source. The closest thing I can find on my receiver is "Auto Surround" but I don't like the way it makes the audio sound.

4) I have the equalizers turned off on all of the applications as well as my ipod. I have tried cranking the Pre-amp on VLC and messing around with the low frequency settings which do enhance the bass/volume, but the result is artificial sounding. Perhaps I just need to spend some more time tweaking them. As far as I can tell other than the settings under the Playback device tab I don't have any other software that manages the HDMI audio settings. I do have the Realtek drivers installed for the SPDIF/analog outputs, but tweaking those does not change my HDMI audio performance and they seem to be specifically tied to the the Realtek HD playback device which is listed separately from my HDMI audio output.

 

[ssddx]

my nvidia gtx470 video card has two dvi connections and supports sound out via dvi. i use the dvi to hdmi cable that came with it (one of the reasons i always buy evga... the goodies).

i do not have nview installed. if windows installs generic drivers then i suppose i have them but nothing extra. when i connect the pc up to the receiver auto-detect shows the receiver under audio devices.

2) how you describe share seems more like a shared device such as over a network instead of anything relevant.

3) i have auto surround as well and that isnt the mode. try cycling through all of them... if your unit is like mine you may have two different buttons on the front panel. one controlls surround sound modes such as action, game, etc and one controlls speaker modes.

4) different receiver audio mode settings can cause a difference in bass output. since the two programs are using two different settings on the receiver this would make sense.

my guess would still be that perhaps your catalyst drivers are screwing with something or your sound mode on your receiver needs to be changed.

normally i just play with the settings until i figure it out.....

i only know what half of the buttons on the remote do... why is there a need for 50+ buttons.........

 

[singemagique]

i only know what half of the buttons on the remote do... why is there a need for 50+ buttons.........

Hah! I feel exactly the same way. I like my Pioneer receiver, but they really need to work on the intuitiveness of their remote control. I'm pretty sure some of the buttons have 3 or more alternative functions.

I think I figured out the problem. I played around with the drivers but ended up reinstalling the AMD because the HDMI audio wasn't working unless I installed their driver. I finally pulled out the 150pg receiver manual and read the entire thing cover to cover. It turns out the setting that worked for me was under Advanced Surround > EXT. STEREO. This puts my stereo source out to all speakers and really enhances the bass response. This makes all my music files sound (in terms of bass) similar to my Pandora One stream. Applying the EXT. STEREO setting also enhances my Pandora One (which was already coming out of all speakers) so much so that a comfortable listening level went from -27dB to -35dB.

I still am not entirely sure why Pandora One outputs a distinct LFE signal (ie. I see the sound waves around the (((LFE))) symbol light up on my receiver) but it may have something to do with the audio codec it uses which is AAC+.

Anyhow I figured the music problem out before New Years, which was what I wanted.

I also read up a bit on Shared Mode audio: http/www.computeraudiophile.com/content/436-jriver-media-center-17-detail/

From the above link:

Note: Some of the following text was also included in the original JRiver 14 article. Windows 7 has not changed these options thus a complete rewrite was not necessary. The Windows operating system uses what's called Exclusive Mode and Shared Mode when handling digital audio. These two Modes affect how Windows and audio applications communicate with audio devices like USB DACs and D to D converters. Exclusive Mode is somewhat analogous to connecting a DAC directly to an amplifier. Exclusive Mode enables an audio stream to go directly to an audio device bypassing intermediate processing. There is no mixing of audio streams from other applications including Windows sounds. The obsolete KMixer from Windows XP gathers all digital audio streams converting them into one sample rate before outputting the homogenized stream to an audio device. This is similar to how other output methods handle audio with layers upon layers of operating system processing and possible manipulation. Exclusive Mode enables direct access to the audio device but does not guarantee anything more than than this. It is one critical piece of the bit perfect puzzle. Shared Mode can roughly be compared to using a preamplifier between a DAC and amplifier. The preamp is there to handle multiple audio streams (among many other things). When a device operates in Shared Mode audio is sent from the playback application to a global audio engine where any number of effects may be applied before finally reaching the audio device such as a USB DAC or audio card. Shared Mode is not recommended for those seeking the best audio quality.

Simple Test:?Users who have a DAC that displays the current sample rate being fed from the music server can run an easy test to determine which Mode is in use. Simply play two tracks with different sample rates. If Exclusive Mode is in use the sample rate on the DAC should change. If Shared Mode is in use the Default Format (sample rate) that is set in the audio device Properties > Advanced tab will be displayed on the DAC. If the Default Format is set to 24 bit, 48000 Hz (Studio Quality), playback of a single 16/44.1 track will provide a quick answer to the Exclusive or Shared Mode question as well.

So this brings up another question: Why doesn't my receiver display the source bitrate of the song I am playing? Does this imply I am not actually bitstreaming the source file to my receiver and instead my HTPC is transforming it to PCM before outputting over HDMI?

 

[ssddx]

now that i've read your post... perhaps EXT STEREO is the mode that i use on occassion. it is so easy to forget the terminology, especially if you dont have the receiver right in front of you to check!

you lost me a little in the lingo but i can tell you that my receiver does not display the source bitrate either and only displays PCM. i cannot tell the difference between the same song played on the pc and via a direct ipod->avr cable so i dont really worry about it.

 

[singemagique]

Thanks for the help! It seems the most difficult part of using a device is understanding all of its capabilities!

 

[singemagique]

Best answer selected by singemagique.