Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[luckyaua]

Hi,
i've this DSP setup for 5.1 music and movies zones:

- Output Format:
     Channels set to "5.1"
     Mixing set to "JRSS"
     "For stereo source only mix to 2.1" CHECKED
     Subwoofer set to "SILENT(using Room Correction to......)"

-Room Correction:
     LEFT and RIGHT speaker set to:   
             Crossover "80Hz - 12dB/octave"
             Routing "Move bass to subwoofer - 48dB/octave"

so with this setup i've measured with REW that the HP crossover is OK on 80Hz  for LEFT and RIGHT speakers but the the bass is routed WIDEBAND to SUBWOOFER than i've to add an LP PEQ at 80Hz to obtain a correct response from subwoofer 20-80Hz....
is normal?

in the attached image:
- normal Sub response using ASIO....so without JRiver (GREEN) 
- response only with jriver routed bass portion from left/right (CYAN)
- response with routed bass portion from left/right PLUS LowPass filter PEQ at 80Hz - 12db/oct (RED)

so you can see that GREEN and CYAN are the same

N:B: the 2 jriver curves (CYAN and RED)  have more bass below 30Hz because in jriver i use a LINKWITZ TRASFORM for my SUBWOOFER!

 

[Bccc1]

Yes, this is normal. DD and DTS audio streams should already have the LP on the LFE channel, so the additional filtering is not needed. For most formats the LFE channel should only contain frequencies <120Hz but for e.g. DVD-A and SDDS the LFE channel has the full bandwith. In these cases you could run into distortion if the subwoofer tries to play back frequencies beyond its capabilities. I don't know the best solution to that.

[luckyaua]

i think that this isn't normal because the subwoofer channel for stereo source is routed from left/right channel so if i route a 20-80hz portion of response from left/right i've to obtain 20-80hz of response for subwoofer created channel!

i've attached the sub frequency response measured with REW for routed bass 12db oct case (GREEN) and 48db oct case (PURPLE)....than the curves are different from 20 to 80hz but then  (i don't understand why!?!?!) from 80 to upper 20000Hz curves realign!! 

[mattkhan]

What are you actually measuring in that graph? i.e. what signal are you using and which channel does it enter jriver as?

[luckyaua]

i use REW to play a sweep 20-20000Hz, REW output to JRiver (WDM DRIVER) out on LEFT or RIGHT or BOTH.

i've attached
- the preferences page of REW (in this case is setting on "both" channels)
- the measure window

[mattkhan]

OK so jriver will see content on channels 1 and/or 2 so that's what it plays back & the differences around the crossover are simply due to the asymmetric slopes. This looks to be behaving as expected.

It sounds like you are expecting to see the sub only in your measurement though, why?

[luckyaua]

i dont'understand....
the measure made by the mic is the sub only....the POWER AMP of left/right speaker are OFF
with this method i've simulated a 2.1 output from stereo track (BOTH option in REW) and i measure only the sub output  of this 2.1 then i except 20-80hz only reproduce by the sub  like i've measured with success 80-20000Hz reproduced by LEFT/RIGHT SPEAKER.

[mattkhan]

Oh ok i didn't realise you had the main amps off. I don't know what is going on there, what does the analyser show if you play full bandwidth pink pn from REW? Does it show a full bandwidth sub or not?

[luckyaua]

tomorrow i try....now is 00:17 AM (Rome, Italy)

[luckyaua]

i've tried...so i think that is a WDM driver issue because the analyzer show a full bandwith for subwoofer with pink noise or sweep from REW or ARTA but if i play , in the same jriver zone, a pink noise or sweep wave files all is ok and the subwoofer reproduce only 20-80Hz like routing settings!!