My FR graph with the PB12-Ultra/2, advice?? (1 Viewer)

[Edward J M]

The meter has a c-weighted filter. Without getting terribly technical, it reads progressively lower as the frequency drops. In addition to the c-weighted filter, the meter has some additional inherent inaccuracies.

There are some correction factors for the RS meter floating around (even the SVS website has it IIRC), that compensate for both the c-weighted filter and the inherent inaccuracies.

The c-weighted filter actually starts to affect the response up around 80 Hz, but it won't become significant until about (as you state) 35-40 Hz. At 20 Hz, I think the RS meter is reading around 8-10 dB low, IIRC.

Also be aware not all RS meters will react the same, so applying a generic set of correction factors to a specific meter will be met with limited success. With that said, for the purposes of basic in-room FR sweeps to identify and correct for large peaks and nulls, it should be satisfactory.

 

[Brian L]

http://www.hometheaterforum.com/htfo...hack+SPL+Meter

Right here in our own SW Archive....

Interesting to note that the write up suggests that these are only accurate with filtered pink noise, but that the loweset readings that were taken to assess the meter's accuracy were in fact done with sin waves.

BGL

 

[Kevin C Brown]

Wes- Let me know if what Ed JM works for you or not. What I did sounds similar to him.

I use the Stryke disc too. I do wish I could get more resolution from 98 Hz (where the Autosounds discs stops) and 160 Hz. I'd like to be able to do every 5 Hz up to about 120 Hz, and then every 10 to 160 Hz... But so far, I'm too lazy to learn how to make my own test tones in the GoldWave (the sound editor software I use.)

Also, I still have yet to plot the PB12-Ultra/2 with EFT5. I will try to do that soon and put the plot up here as well. (Oh yeah, and a reminder to myself to lengthen the gate time up to 500 ms from 200 ms to get the room nodes... )

 

[Brian L]

http://www.esser.u-net.com/ttg.htm

Check this out...

Bone head simple. I just made a CD with sin waves to match the frequency centers of my AudioControl Bijou, which runs up to 800 Hz..

The trial version will only burn a 3 second tone to CD...but the full version is only $26, which will do any length.

Very, very cool program.

BGL

 

[Kevin C Brown]

Nice. A little more user friendly for just tone generation than GoldWave...

 

[Timber]

These are all good things to know. Thanks guys.

Tim

 

[Kevin C Brown]

I finally got my better than 1/10th octave test disc done. Here's the results:



1) Better resolution is just that. Allows you to see worse peaks and dips.

2) I am using a 60 Hz crossover. I need to work on the phase setting to adjust what's going on there. Note the overall valley below 60 Hz and the overall peak above 60 Hz.

And ... once I get the phase set correctly, I bet I can get to +/- 5 Hz from 11 to 90 Hz. Yes, 11 Hz. That's with no eq too. Sub in the corner.

I'll post more graphs when I get plots with ETF5 and the SVS. Much easier to adjust phase with ETF5 than manually plotting points.