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LFE crossover has to be set in both Win 7 and/or AV amp?

post #1 of 7
Thread Starter 
I have analog 5.1 audio out from my Win 7 Ultimate HTPC with Sound Blaster X-Fi sound card to Onkyo 705. My issue is that the rig has a schizophrenic approach to bass cross-over: MP3 music files don't get a cross-over unless I set it in the computer, but AC3 and DTS movie files do regardless of the computer settings.

If I don't have cross-over set in Sound Blaster control panel, I don't get bass redirection at all to the sub with MP3 audio files. But when I test with AC3 and DTS (movie) files, the Audigy-set bass redirection at 100hz in the Onkyo works fine, and low frequencies are re-directed to the sub. If I set a cross-over in SB control panel, I get bass direction with all types of files.

So, how should I set my cross-overs in the AV amp and Sound Blaster control panel? Should I set them to the same frequency in both at 100hz, or different levels to have some overlap? I'm mostly concerned about losing any frequencies, and of course not damaging the AV amp or my speakers.
post #2 of 7
If you must decode 5.1 audio in the HTPC, then you cannot apply further processing in the Onkyo, as you are sending 5.1 analog to the Onkyo's M-ch analog bypass to drive the speakers. In that case yes you have to entice the X-Fi to perform bass management on everything, because when using analog bypass the Onkyo's crossovers are not in effect.

However, might it not also be possible to let the Onkyo play a bigger role? For MP3 (or any stereo audio in the HTPC) if you can get 2-ch PCM audio from the S/PDIF connection on the X-Fi, then the Onkyo can treat it with whatever processing you like, including bass management, Audyssey room EQ, or even surround decoding.

Same idea for DD and DTS files, as their bitstreams travel over S/PDIF if you can tell the HTPC to "bitstream" instead of decode. Then you can presumably enjoy the full potential of the Onkyo, and full control of the bass management.
post #3 of 7
Thread Starter 
Quote:
Originally Posted by Roger Dressler View Post

If you must decode 5.1 audio in the HTPC, then you cannot apply further processing in the Onkyo, as you are sending 5.1 analog to the Onkyo's M-ch analog bypass to drive the speakers. In that case yes you have to entice the X-Fi to perform bass management on everything, because when using analog bypass the Onkyo's crossovers are not in effect.

However, might it not also be possible to let the Onkyo play a bigger role? For MP3 (or any stereo audio in the HTPC) if you can get 2-ch PCM audio from the S/PDIF connection on the X-Fi, then the Onkyo can treat it with whatever processing you like, including bass management, Audyssey room EQ, or even surround decoding.

Same idea for DD and DTS files, as their bitstreams travel over S/PDIF if you can tell the HTPC to "bitstream" instead of decode. Then you can presumably enjoy the full potential of the Onkyo, and full control of the bass management.

I'm not sure I understand. You said that the Onkyo can't process the 5.1 analog input from my HTPC, but why does AC3 and DTS audio get processed - ie. have the crossover applied?

I'd use SPDIF, but no PC games I know outputs 5.1 audio through SPDIF, only analog. I'm trying to keep things simple, and only use one set of cables for all audio.
post #4 of 7
Quote:
Originally Posted by jouko342 View Post

I'm not sure I understand. You said that the Onkyo can't process the 5.1 analog input from my HTPC, but why do AC3 and DTS sound gets processed - ie. have the crossover applied?

Compression, as in dynamic range compression? That is not directly related with bass management. So now I'm confused.

The Onkyo (like most AVRs) have a 5.1 analog input, but it has no A-D converters for that, so it stays analog. The bass management is only in DSP, so it cannot do that nor can it alter dynamics. That has to be happening wherever the DTS/DD are being decoded.

Originally you said: >>But when I test with AC3 and DTS (movie) files, the Audigy-set bass redirection at 100hz in the Onkyo works fine, and low frequencies are re-directed to the sub.<< How do you know bass redirection is turned on? Even if it is off, the LFE channel will make the subwoofer active.

Do you hear a difference in dynamics when you change bass management settings?

Quote:


I'd use SPDIF, but no PC games I know outputs 5.1 audio through SPDIF, only analog. I'm trying to keep things simple, and only use one set of cables for all audio.

Understood. You can do that, and if it works as desired, no problem.

If you want the Onkyo to handle all the audio processing, you'd need something like DD Live or DTS Connect to convert the game audio to S/PDIF.
post #5 of 7
Thread Starter 
Quote:
Originally Posted by Roger Dressler View Post

Compression, as in dynamic range compression? That is not directly related with bass management. So now I'm confused.

The Onkyo (like most AVRs) have a 5.1 analog input, but it has no A-D converters for that, so it stays analog. The bass management is only in DSP, so it cannot do that nor can it alter dynamics. That has to be happening wherever the DTS/DD are being decoded.

Originally you said: >>But when I test with AC3 and DTS (movie) files, the Audigy-set bass redirection at 100hz in the Onkyo works fine, and low frequencies are re-directed to the sub.<< How do you know bass redirection is turned on? Even if it is off, the LFE channel will make the subwoofer active.

Do you hear a difference in dynamics when you change bass management settings?

I didn't talk about compression or DR anywhere

I see what you're saying about the AD converters. That's a bummer since I output most of my audio from my HTPC, so Audigy settings are not applied. I'll have to look into SPDIF out for movies as an option, as my card seems to support DTS Live which is shockingly a reasonably priced download.

But I still don't understand why I get sound from sub with AC3 and DTS audio, but not with MP3s if I have bass management off in SB control panel. If it's on, I get bass from sub with all audio files I've tried.

You said "Even if [bass redirection] is off, the LFE channel will make the subwoofer active". It should, but it doesn't with MP3s. That's why I'm asking how is it possible that the LFE channel is not activated with MP3s when bass management is off in SB control panel.

I certainly here the difference in dynamics, as my non-sub speakers can't really output much below 100Hz. I also verify the sub is working by touching the speaker cone.
post #6 of 7
Quote:
Originally Posted by jouko342 View Post

I didn't talk about compression or DR anywhere

OOPs, I meant to say Department of Energy.

Quote:


I see what you're saying about the AD converters. That's a bummer since I output most of my audio from my HTPC, so Audigy settings are not applied. I'll have to look into SPDIF out for movies as an option, as my card seems to support DTS Live which is shockingly a reasonably priced download.

Would be worth trying, especially if you want the other Onkyo features like room EQ.

Quote:


But I still don't understand why I get sound from sub with AC3 and DTS audio, but not with MP3s if I have bass management off in SB control panel. If it's on, I get bass from sub with all audio files I've tried.

Even with bass management off, 5.1 signals can deliver audio to the subwoofer via the LFE track.

Quote:


You said "Even if [bass redirection] is off, the LFE channel will make the subwoofer active". It should, but it doesn't with MP3s.

I was referring only to DD and DTS there.

Quote:


That's why I'm asking how is it possible that the LFE channel is not activated with MP3s when bass management is off in SB control panel.

There will be no subwoofer activity from stereo audio when bass management is turned off.
post #7 of 7
Thread Starter 
Oh ffs, after further research the digital out of SB Xtremegamer Fatal1ty Pro only supports stereo. I need a hardware SB I/O console to get 5.1 digital out, which appears to have been discontinued.

That's what I get for buying Creative years ago - I thought they had learned from their earlier mistakes, boy was I wrong.

Anyway, thanks for help!
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