Bought my BFD and I Have Questions (1 Viewer)

[Bob U]

Thanks, Bruce. I'm off to go read about Servo 15's
-=Bob=-

 

[brucek]

Wyatt,
I don't know much about HP CDR software - sorry. The tone generator I suggested creates a 44.1KHz 16bit mono wave file. This is the best thing to use for doing frequency response checks in my opinion.
I create 4 second tone files and burn them using EZ CD Creator without any problems. A lot of people use this burning software - maybe you can have someone burn the files for you. A four second wave file is about 345K.....
I'll tell you about the two CD's that I use. You might be interested.
I have two CD's that I use myself. One is a CD with every one Hertz frequency from 10Hz to 80Hz and then 1/6th octaves up to 160Hz. It's good if you wanted to narrow in on some specific frequency.
Then the second CD I have is the one I use all the time and is simply 1/6 octave tones from 16Hz up to 160Hz. This allows me to quickly do a response check of my sub without fooling around with track numbers, it progresses up through the tracks using the same frequencies as my Excel graph.
For this CD I used 40Hz on the tone generator as my center starting frequency to create the tones. Here are the resulting center frequencies of the tones I use and their associated "named frequency"...
16(15.874),
18(17.818),
20(20.001),
22(22.450),
25(25.199),
28(28.284),
31.5(31.748),
36(35.636),
40(40.000), center frequency
45(44.899),
50(50.398),
56(56.570),
63(63.498),
71(71.274),
80(80.002),
89(89.799),
100(100.796),
111(113.140),
125(126.996),
143(142.549),
160(160.005).
So you can see that the named ISO standard frequencies are not exactly the same as the calculated frequencies. In this case I used a center starting frequency of 40.000 Hz. If I take each ISO named frequency and calculate the 1/6th octave below it, then the named frequencies for 1/6th octaves will be very close.
So it's really a matter of choice if you want to manually enter the "named frequencies" into the tone generator and save them as such, or start at say 40.000Hz for example as I have and then use the built in 1/12th octave function in the tone generator to calculate the tones (as I've listed) as your frequencies to save.
Let me explain.
In equal tempered tuning there are considered to be 12 equally spaced notes per octave. As you already know it is accepted that if you equalize a subwoofer to 1/6th octave tones, that the response will sound correct even if there are some anomalies between these tones. So we use 1/6 octave tones to do frequency response checks.
The values on the Excel graph on Sonnies site aren't exact center frequencies but are the "named preferred numbers" because the exact 1/6 octave equal tempered tones are taken to three decimal places and will be different depending on the accepted starting center frequency. These are close approximations or named frequencies and work very well. So while the 1/6th octave below 40Hz may be exactly 35.636Hz, the named ISO frequency is 36... The standard named preferred frequencies I believe is referenced to a starting center frequency of 1000Hz.
The tone generator you're using that I referenced is very useful in this regard. If I enter a frequency, then every mouse click on the +/- to change the frequency is a 1/12 octave jump from that center frequency. Pretty handy. Enter 40.000Hz and click twice on minus and your 1/6 octave below at 35.636Hz (36). Click twice more minus and your at the next 1/6 octave down at 31.748Hz (31.5). Click twelve times and you're at 20.001hz = one octave below 40Hz.
So if I choose any starting center frequency, say 40.000Hz for example, the exact calculated 1/6 octaves as referenced to the named frequencies on Excel graph would be as listed above and are the ones I use. The frequencies on the graph are the named frequencies.
But if I chose 1000Hz as my starting point and calculated all the exact 1/6 octaves below it, these numbers would be slightly different than above because for the ones above I chose 40Hz as my starting frequency. You're right, it is boring.
Anyway, what I did to make my CD was enter 40.000Hz as a frequency into the generator form fill, then clicked minus until I got to 15.874Hz and did a save as 16Hz. Then I click twice to increase by a sixth octave and I'm at 17.818Hz and save as 18Hz, the click twice more and I'm at 20.001Hz and save as 20Hz etc and so on until I get to 160Hz. These are then my wave tones..... Get it?
brucek

 

[Bob U]

Well guys, both sunfires sold in about 18 hours on Ebay.
Just ordered 2 SVS PCi25-31's tuned to 22 Hz. Watch for new graphs in a few weeks
-=Bob=-

 

[brucek]

Bob,
No doubt you're money ahead.
I'll be very interested in seeing how the new subs perform in comparison to the Sunfires.
Now you have to go through the whole equalization procedure for another time. You got experience working for you though...
brucek

 

[Bob U]

Its true! Even after Ebay and PayPal fees and shipping, I made over $300 on the deal. That's going to go to either new mains stands or better room treatment.

You can be sure there will at least be a graph of the non-BFD'd room the day UPS shows up. I think I am going to EQ each SVS on a separate channel of the BFD this time, so much more data to come.

-=Bob=-

 

[brucek]

Bob,

You can be sure there will at least be a graph of the non-BFD'd room the day UPS shows up. I think I am going to EQ each SVS on a separate channel of the BFD

Although, you may not be able to get the coat hanger smile off your face long enough to get down to business..
I would probably run each from its own BFD channel as you say, but I would start out in "couple" mode in the likelyhood that they'll EQ very similar. Then you could de-couple later and individually tweak if you thought it was needed..
brucek

 

[Bob U]

I *think* I just discovered a problem with my BFD.
A little background: The other day I was tweaking (it never ends ) and playing the Stryke disc at about 80dB through my DVD player, pre/proc, BFD, powered subs. The level jumped about 20dB. I quickly shut ebverything down and tried to figure out what happened, but no luck. It was fine again after that save for a tiny bit of diginoise for just a few minutes when I went back to tones.
Tonight, system was off, subs are gone and nothing connected to the output of the BFD. Had a brief (5-10 sec) power failure. When I went downstairs just to check things, the outputs of the BFD were pegged at clipping. I keep the BFD always on to prevent turn on transients, so when power came back, it was the only device in the system to power up.
I think this is what might have happened while tweaking the other day. I'm afraid to keep using it at the moment.
Just emailed Behringer. Hope I can get it exchanged as it is only a month old.
Any thoughts?
-=Bob=-

 

[brucek]

Bob U,
This device is a processor, (although dedicated) like any other, and can "hang up" when executing its start up sequence. Ever have Windows hang up your computer?
If you were able to subsequently shut off and then successfuly power-on the BFD, it may simply be an isolated incident caused by the power bump.
Then again, you may indeed have a fault. Hard to tell at this point. Behringer may simply replace it, given its inexpensive price. It will be interesting to see what they do for you.
brucek

 

[Bob U]

This device is a processor, (although dedicated) like any other, and can "hang up" when executing its start up sequence. Ever have Windows hang up your computer?

Sure, but I don't have Windows connected to the input of a power amplifier And if it hangs at full output, this is a major problem!
The BFD is connected to a Monster HT2500 power conditioner, so it should not have seen a spike, just turn off and on.
I'll post when I hear back from Behringer.
-=Bob=-

 

[Bob U]

Talked to Behringer US and no insight, but 1-6 weeks to repair depending on parts. So called my dealer and he will exchange it for me. So, may never know what the problem is/was.

Just a head's up to all BFD owners that this can happen. I hope it was a one in a million fluke.

-=Bob=-

 

[Bob U]

Just posted this in another thread re: my new SVS subs:

Well, they're here and unpacked and roughly setup.
Surprised they weren't double boxed, but although the outside cartons showed traces of UPS, the only damage was that one logo had fallen off. And they smell like a new car
BUT, although they sound better than my Sunfires, they don't sound anything like they did at Brian Fellmeth's house. I'm balanced at 75dB front and rears and 78dB on the subs. In phase reads 1dB higher than out of phase. I have NOT yet measured nor inserted the BFD. There is no room pressure as there was at Brian's.
I'm going to email Tom as soon as I finish this post then continue the discussion over here:
Bought my BFD Thread
More soon.
-=Bob=-

So, do these need a bit of break-in? Is my room just that bad for bottom end? Any thoughts?

 

[Bob U]

Well, the frequency response without the BFD is pretty ragged. Biiger bumps and deeper dips than with the Sunfires.

I'm still moving and measuring without the BFD in right now. Back with a graph in a little while.

 

[Bob U]

Ok. Here is the first of the SVS charts. Should be self explanatory and is interesting how the two subs combine in the room.
Link Removed
-=Bob=-

 

[Brian Fellmeth]

Hey Bob,

Those curves look brutal. Your probably calibrating on that 33 hz hump, and if the program material is lean at 33 Hz, the sub will end up too cold. Looks to me from those curves that your running them separated by each main like the sunfires were. Your "sum" curve I presume is both subs playing and you've LOST SPL over a significant portion of the specturm- that is cancillation. Although it would degrade the elegance, try stuffing them both in one corner, do a quick and dirty BFD correction with one or 2 filters (hit that 33 Hz monster). and I gurentee you will duplicate what I had at my place, even though you've got much more air to pressureize than I do. From that point, you can work your way back to stereo sub configuration.