test tone settings seem low

**corock** · **09-21-09, 02:50 PM**

I'm using REW and a BFD DSP1124P for the first time. When I set the levels to do the measurements, I have to put my PB13-U gain down to 7 o'clock and the sweep level down to -17 to acheive 75db on my RS SPL meter. The meter is set to C weighting and slow response. My laptop has input and output line jacks so I'm using the internal Realtek soundcard. I have the REW test tone output through the headphone jack into the BFD, bypassing the AVR. The RS meter is input to the laptop line in jack. I did calibrate the soundcard. The measurements produce normal frequency charts and the applied filters flatten the results out. But I have to crank the gain on the sub to 12 o'clock to get any resonable amount of bass. The trim level for the sub is set at -6 to keep the input level to the BFD from clipping at the levels I listen at. It appears to me the levels for taking measurements are low and I'm not sure if I'm doing something wrong or if they're fine like that.

**brucek** · **09-21-09, 02:59 PM**

Quote:

into the BFD, bypassing the AVR

Why are you doing this? The standard method is to feed the AUX or CD input of the AVR from your soundcard line-out, and use the AVR's volume control to set the 75dBSPL at the listening position. The AVR allows you to engage the bass management crossover you would normally use. That way the sub will output the crossed signal that you regularly listen to.

brucek

**corock** · **09-21-09, 03:34 PM**

Thanks, that makes sense. My reasoning was to defeat the main speakers so I could graph just the sub. My Denon 4308ci doesn't allow me to shut them off and its actually a chore to disconnect them at the avr or speaker connections. I guess nothing good can happen without a little sweat.

**brucek** · **09-21-09, 06:43 PM**

Quote:

My reasoning was to defeat the main speakers so I could graph just the sub.

Yeah, most AVR's have a switch to shut off the mains or switch to an empty set of B terminals, but if not, you just have to disconnect them. It's only the mains you need to remove since REW is to be used with the AVR in stereo, all your other surround and center speakers can remain hooked up.

brucek

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