Rookie Q's on REW

[pbc]

Finally started to use REW, and went through the help and Soundblaster Live threads and think I have set everything up right.

I'm using an SMS-1 with the most recent firmware fixing the subsonic filter and distortion issue. Have set the subsonic filter to 1hz and the slope to 6db/octave on the SMS-1 (I have a PB13).

When I hit "find peaks" to have the REW help with the SMS1 settings, I get an "Find Peaks Warning" that says "The Target Level may be set incorrectly (too low) or teh speaker type or Cutoff may be incorrect, giving a Target response that is much lower than the measured response within the peak search range". The Target level is 78.9, the largest peak found was 33.7db. Speaker type is subwoofer and crossover set to 24db/octave, cutoff is 80.

Something is obviously incorrect, as when I try to assign filters all the filter adjustments are north of 120hz, execpt for one at 35hz and one at 38, and all indicate to cut 12db.

My measured graph (uneq'd) is below ... help!

PBC

[brucek]

You still have your mains on, so observe how much signal is above the target after the 80Hz crossover. Turn off your mains and redo the measurement. Always measure the sub only to start the equalization and measurement process.

In addition to that (once you have your mains off) I would set the Find Peaks maximum to about 100Hz. There is little reason to filter above that frequency since the mains will overwhelm the situation when turned on above the cross.

Filters 7 and 8 at 35Hz and 38Hz look correct to remove the one real peak you have to deal with. As far as the peak at 18Hz is concerned, the default minimum Find peaks frequency is usually 20hz (since that's as low as a BFD will filter). I do believe you can set the minimum lower to 15Hz for an SMS though..

brucek

[pbc]

Thanks Bruce, noticed on another thread you had recco'd keeping mains off, I also had the amp in dolby PLII mode and not stereo, so I corrected that as well.

Also adjusted the peak minimum to 15. Will run some graphs later.

PBC

[pbc]

Okay, one more question as I'm back at it. When I perform a "check levels" procedures, I need to pump up the volume on my AVR until the Galaxy meter reads 82 to 85ish to get an adequate input signal (to get it to around the "ideal" -18db. I have the volumes at max on the sound card, and have set the Output device and input devices accordingly (SB Live, Speaker, and SB Live, Line-in), finally, all items are set to 1.00 (Wave/Input/Output volumes, and Sweep level is at it's highest -3.0 setting).

The help file seems to indicate the SPL meter should read closer to 75db here, so I'm wondering if I'm doing something else wrong? Again, this is sub only measurements, AVR set to Stereo.

Sorry for the questions, trying to read up as much as I can but can't figure this one out on my own!

Tx

[brucek]

SB Live, Speaker, and SB Live, Line-in

Yeah, some members have reported that they can't get enough input level, as if the SPL meter isn't outputting sufficient level or perhaps the soundcard requires a higher level than other cards - I don't really know why. I have three different soundcards myself and I can hardly set any of them above about 30% of their input volume swing before they clip. Yet others can't get enough volume with the input levels at 100%. I just don't understand why.

Are you sure you are using stereo plugs at the soundcard line-in jack?

Do you have the meter range selection at the correct position - since the lower the range, the higher the voltage output...

brucek

[pbc]

Here are two post calibration pics. One was calibrated with only the sub on (sorry, the target level didn't save for some reason) and the second was recalibrated with all speakers on. The sub only one looks decent, but once I turn on the speakers (all set to small, 80hz cross over) it becomes disasterous?

[pbc]

Are you sure you are using stereo plugs at the soundcard line-in jack?

Yup

Do you have the meter range selection at the correct position - since the lower the range, the higher the voltage output...

Range set to 50 to 100. C weighted, slow.

[pbc]

Just to confirm, I have a stereo plug into the Line in, with a mono adaptor and mono cable out to the Galaxy CM140, which I believe is correct?

Tx

[brucek]

The sub only one looks decent, but once I turn on the speakers (all set to small, 80hz cross over) it becomes disastrous?

So when you say all the speakers are set to small I hope you simply mean you added just the two mains?

Anyway, I don't think I've ever seen the mains when set to small at 80Hz, actually have that negative effect on the subs response down at 25Hz. I don't get it?

There's something else at work here, because you can see on the picture below how much signal is available at 25Hz from the mains... In fact there's almost no signal available to modify the subs output like shown in your graph. I can't explain it. There is a measurement anomaly of some sort.



brucek

[pbc]

So when you say all the speakers are set to small I hope you simply mean you added just the two mains?

Well, the receiver is in stereo mode so I believe that only enables the fronts and sub (Denon 2802 model).

The sub appears to be six db down at 80hz with the speakers on or off?

Guess I'll try recalibrating the mic again and try measuring at a later date. Strange.