sub hums if I turn on SPL meter

[subby]

You know any cheap extern soundcards around that price that will defenetly do the job? Because here in Belgium we don't have the Soundblaster 24bit Live! soundcard and it's already 40$.

[subby]

Or is there maybe another possibility how I can know witch frequenties that are too loud and try to do it manually just with the BFD for now untill I have another soundcard and give REW another try?

[subby]

Ok, Brucek, I forgot to thank you for your great help so far. I really appriciete it.

After a week of rest I tried our pc's onboard soundcard wich also seamed to have a line in and line out. The problems of the soundcard calibration and spl signal with the checking levels routine were solved. But I stumbled upon some weird measurements that are far from what I expected. And I'm confused if the volume of the sweep level was't too loud.

[IMG][/IMG]
This first measure was done right after the checking levels routine and spl calibration. I did the checking levels as was told and got to about 12db fs. When I did the measure routine first I suddenly got to a headroom that got close to clipping (about 1.5db fs). But when I looked at the graph I was amazed that the peak of 20hz was only so small while during movies the bass seamed to boom more towards the subsonic frequenties then the 40hz. I'm even more astound that there is a drop between 25hz and 35hz.

[IMG][/IMG]
before I did the second measure I changed the settings on my soundcard volume panel as instructed in the REW help file. I switched Volume and lin in meter to halfway. then I got to a graph that is more alike with REW's graph. I don't know how to enterpret this graph really and I'm confused if I did the right thing with changing the soundcard levels. During the checking levels rumble the volume was fine but the sweep level almost seemed much louder. I also changed the smoothing octaves to 1/3.

[brucek]

OK, I see a few problems.

Never use smoothing for subwoofer frequencies. This is only used when measuring full range.

Note that your graphs are in the LINEAR mode. Change them to LOG mode by clicking on the Freq Axis Icon at the top right hand side of the REW screen.

Also set the horizontal axis to 15hz-200Hz and the vertical axis to 45dB-105dB using the Graph Limits ICON at the top right hand side of the REW screen.

brucek

[subby]

Ok, I'll try that. But now I still don't know wich of those 2 graphs I did correct. And is it normal that the sweeping sound during the measure routine is louder then the rumble during the check levels routine?

Also, I turned my receiver to CD mode for the checking levels because in DVD mode it didn't work. But I know that the bass levels in CD mode are a but softer then in DVD mode.


This is a new graph I took this morning. It was done with the normal levels that were set during the checking levels routine. But during the measuring sweep REW recorded clipping. That's weird because during the checking levels routine the level was just 12db as instructed by REW. I also don't if it's the black line or the blue line that's REW refference line.


Does this look ok? I still think it's very weird that there is't really a peak around 20 - 30Hz. I'm sure that the boom I sometimes hear is beneath 30Hz and especially in bass tones in filmscores. Maybe I did the sweep too low?

[subby]

ok, I did quit a lot of tweaking during the past week and managed to get rid of the peak at 40Hz, 62hz and 75Hz and push the 51Hz dip up. The result is quit pleasing. The bass is more controled and sounds even more tight and detailed sometimes. But most of all it sound more pleasant to listen at. No more loud booming bass that cause me a headake. this counts especially for the deep basstones in filmscores that previously caused a boom in my room.

I'dd like to thank you very much for your help brucek!

I'dd might to a bit of experimenting in the future to get to a beter result but it probebly will not get much better then it already is.

[JohnM]

Remember to select "Optimise PK Gains & Q" after you "Assign Filters", the initial filter assignments REW makes are just starting points for the optimisation.