for Behringer (BFD) owners - questions (midi, settings, results.. etc) (1 Viewer)

[Mike Dr]

I just got the 1124p .. after hours of playing and trying to figure it out i think i got some results..

I used SpectraPLUS with radio shack spl meter as microphone. Did some graphs before then tried tuning .. my problem is i have a BIG dip at 32hz in my room .. (probably around 15dB if not more).. so I tried to bring the rest of the curve down significantly while bringing the dip up a little bit.. i got a flatter curve now but i dont know if could do better.... the other thing is setting it up .. its not the most user friendly interface so i figured I'll use the software. I have midi cables.. could not get the midi to work recieve OR transmit .. anyone have problems with this?

Also, new to this model is a different input level adjustmetn.. a -10dB and a +4dB .. which one should i be using?

and finally .. if i have a choice of raising the sub level in the Receiver (LFE level), in the BFD (assuming i got into the plusses) or the analog volume knob on the sub itself, which will degrade the signal the least/most?

any other tips will be very welcome

thanks

 

[Philip Hamm]

I'm moving this to the Advanced area, I believe the clientelle there will be happy to answer and it will get quickly buried in the very busy Hardware section.

 

[David Judah]

Use the -10db setting, and raise the level on your receiver(overall sub level, not LFE).

DJ

 

[Kevin C Brown]

You should actually use the analog knob on the sub 1st, then the receiver's sub level 2nd, and the BFD last.
Increasing the level in the receiver alone can sometimes overload a sub's input.
I found the BFD easy enough to use, one you slog through the less-than-user-friendly-but-very-information-rich manual!

 

[Mike Dr]

David what do u mean by "overall sub level, not LFE" .. the sub level on the receiver IS the LFE .. i only have one internal adjustment .. its called Subwf or something like that.. thats the one i'm adjusting.
keep em coming

 

[Wayne A. Pflughaupt]

Mike,

Any real time analyzer, be it stand-alone or software-based, is only as good as the microphone feeding it information. Stand-alone RTAs are calibrated to be used with a specific mic -- that is, it adds compensation to the mic’s characteristics to deliver flat response.

That said, I hope there was something in the Specta program to tell it specifically what mic you were using. I wouldn’t put much stock in any non-corrected readings.

Happy Holidays,

Wayne A. Pflughaupt

 

[brucek]

Fiddler,

Actually the 1100P also has the input sensitivity selection capability of -10db and +4db.

The -10db is actually -10dbV (which calculates to 315mvolts) and should always be used for home use - line level equipment. This will ensure the system is receiving the spec'd "nominal" level. The spec indicates max input and output levels of +2dBV at the -10dbV sensitivity setting.

The +4db setting is +4dBu (which calculates to 1.24volts) and is for pro equipment.

This brings me to your second question of level setting. When you use a line level piece of equipment such as this between a sub and preamp you have to set your preamp levels to accommodate the BFD first and then set your sub volume level to suit once that is done.

The reason for this is that your BFD can have linearity or clipping problems if not taken care of first. The output of your preamp isn't a fixed optimum max line level as would come out of a CD player for instance, which would have a predetermined maximum line signal that you could match easily to the BFD's max input sensitivity. In that case you would be operating in the best linear region and the maximum input would not clip and the softest signal would satisfy the ADC (analog to digital convertor) quite well.

Instead, in the case where we use a BFD after a preamp, this is a line level that is variable because it's controlled by a volume control on the preamp.

This presents two problems.

If the "sub or LFE level" is too high and you crank the preamp volume too high, you can easily clip the BFD signal as indicated by the red LED's and if you set the sub level too low, you'll be feeding the ADC with a very small signal and moving more into a low level distortion area which ADC's tend to suffer from if fed too small signals (quantization noise).

Your best bet is to first set your preamp sub output to zero and then play a DVD with some heavy bass (like U571). Turn up the volume to about as loud as you think you'd likely want and observe the LEDs on the BFD. Now set the preamps sub out level so the red LED's are just coming on. This is just before clipping. Believe me, you don't want to send your sub a clipped signal. I've done bench tests on my BFD and the red led comes on at about 1.5vpk and clipping occurs at 1.6vpk. This is a good level to leave the preamp sub out. Now go ahead and set the volume on the sub that you want.

Another thing you'll want to do is add about a foot to the distance setting for your sub when setting up the processor delays for your speakers. This will compensate for the fixed DSP processing delay of about 1 msec in the BFD which will cause a linear phase shift. One foot will take care of it.

brucek

 

[David Judah]

That said, I hope there was something in the Specta program to tell it specifically what mic you were using

The demo version I downloaded, at least, had corrections for a Radio Shack SPL meter, which Mike was using.
Did you add it in in "microphone compensation" in the scaling menu, Mike?
DJ

 

[jeff peterson]

David, the version I downloaded had this mic file: RADSHACK.MIC, but if you open the file in notepad; you'll see it's for Radio Shack low cost condenser mic (P/N 33-3007) NOT the SPL level meter's microphone. I cut and pasted the following values from Tom V elsewhere on the board:

0 -20.0

12.5 -16.5

16 -11.5

20 -7.5

25 -5.0

31.5 -3.0

40 -2.5

50 -1.5

63 -1.5

80 -1.5

100 -2.0

125 -0.5

160 0.5

200 0.5

250 -0.5

315 0.5

400 0.0

500 0.5

630 0.0

800 0.0

1000 0.0

1250 0.0

1600 0.5

2000 1.5

2500 1.5

3150 1.5

4000 2.0

5000 2.0

6300 2.0

8000 2.0

10000 1.0

12500 -0.5

16000 0

20000 -1.0

 

[David Judah]

Thanks for the info., Jeff. When I saw the file, I just assumed it was for the spl meter. That's good to know.

DJ

 

[Mike Dr]

I did use the compensation and i made my own file from compensation tables i've found on the web for the SPL meter. Of course there are still errors but it's close enough for me

 

[jeff peterson]

A while back, I found a posting for the settings to use in Spectraplus for SVS (or any subwoofer) calibration. It was the values for decimation ratio, sampling rate, and FFT size. I printed the settings but now can't find it :frowning:. Can anyone direct me? I tried the search function with no luck.