TrueRTA questions...

[ABlakeG]

Hello there. I have reached the point where I feel that I need to address my room before anything else (component upgrade and whatnot). I bought the following programs to aid my journey --

TrueRTA level 4
ETF (with mic and preamp -- not yet received)

My associated equipment is Lexicon MC-12B v4 (room EQ), ATI 3007 amp, Dynaudio Confidence 2 speakers, and 2x SVS PB12+/2 subs (run as right and left subs from the Lexicon)

My room is 12x14x9, 5/8 drywall over 2x4 studs, which are attached to concrete (room is mostly underground)

I am also using a Behringer ECM 8000 mic and one of their preamps to supply power in the interim. I used my computer sound card, which tested properly in the self test, so I assume that the mic in and line out were working OK. I played some sweep tones through my system, and here is the resulting graph -- I think that it is accurate, but that is what I am asking help with. I would like to use a BFD to EQ my sub flat. This measurement was taken in 2 channel, with subs engaged, crossed over at 60hz. The room EQ, which supposedly works only on resonance in-room, was engaged. I used my normal volume level, which is -15 below reference on my volume control.

Image not available

Sorry about the readability of the graph -- it is from 50hz - 10hz, 1/24 octave.

Does this look like reasonable low-freq response? I think that it is too high -- I know that the subs I have are pretty capable, but this just seems like too good to be true. I just want to know if I am reading this right, using the software correctly, etc.

Thanks for any help or suggestions.

Blake

[ThomasW]

You can change the colors in TrueRTA so that it's easier to see. Also the bar graphs are easier to read.

The room EQ, which supposedly works only on resonance in-room, was engaged.

Turn it off and remeasure. For a sub 1/12th octave is all you need. And turn down the level, you only need 80-85dB output for testing purposes

[ABlakeG]

Thomas --

Thanks for the suggestions. I must be stupid, though. Last night I went to measure my response again, and I was getting levels in the 110+db range, and it was barely audible through my speakers. I am beginning to wonder if I have the set-up correct? I was using sweeps from 100-10hz, and controlling the volume on my pre-amp. The lights on the Behringer mic pre were barely lit (the signal level lights) and yet it was measuring huge numbers.

To make sure that I have this correct, I go mic-micpre-mic in on sound card, and the line out(analog) - analog in on my lexicon. that should be right, correct?

Thanks for any help. Sorry for the basic questions. TrueRTA said to max out all the levels in my computer -- should I be adjusting those?

Blake

[Bruce]

I don't know about your soundcard, but technically you should be using LINE-IN (NOT mic-in) on your soundcard, because you input is coming from the LINE-OUT of the mic's preamp. In your PC's sound mixer control panel, you should actually have the the slider for the mic input turned off (MUTE).

[ThomasW]

TrueRTA said to max out all the levels in my computer --

That's for calibrating the soundcard.

You use the volume control of your pre-amp or receiver to set the SPL from the woofer.