Picked Up a Behringer FBD

[Bing Fung]

I Picked up a Beringher Feedback Destroyed today, Seems pretty cool so far. This is what I have been needing for now I can adjust my sub

What type of bandwidth should I set my filters to? 30-1/60, 60-1/60, 120-1/60?

Holy speaker thump on power up or down.. It this normal? Anybody with one just leave it powered on?




Bing

[ThomasW]

Don't have one, but here general Pro EQ info.

There is an order when turning on/off components. The power amps are last on, first off. This should solve the "thump". The FBD like most pro stuff doesn't have output relays. Hence the turn on thump. Otherwise just leave the FBD on all the time. I'm sure it draws minimal power.

The great thing about parametrics is that you can choose the width of the band based on your need. 1/3rd octaves are of course limited to that 1/3rd bandwidth. With the parametric you choose the bandwidth with appropriate for the peaks you want to correct. Narrow for a narrow spike, wide for a big hump. 1/60 of an octave is very narrow. Remember an octave is anywhere the frequency is doubled so 30Hz-60Hz is one octave, so is 20Hz-40Hz. With a parametric you define the octaves and you define how much or how little of the band the EQ controls.


DO NOT try to boost nulls! Only cut peaks and do smoothing by using the "cut" mode. Trying to boost nulls is impossible, and a huge waste of amplifier power




theAudioWorx
Klone-Audio

[Bing Fung]

Thanks Thomas, now that I know the only true way to use this is to measure the in room sitting response, and then adjust the BFD accordingly.

So, when I'm measuring the sub at sitting posistion, do I have just the sub running, or do I have all speakers on?


Can you recommend proper calibration techniques?
Do you know if the Panamax, or Monster power conditioner can be programed to power up and down the equipment as you suggested?

What do you use to control 12 Shivas dancing Thomas?




Bing

[ThomasW]

Bing

I manually turn all my equipment on and off. Nothing controls the IB. There's 6db of shelving boost built in to the active XO for the IB.

I'm not familar with either the Panamax or Monster devices. I use a very old Tice PowerBlock/Titan II combo for power conditioning. It consists of 2-66lb transformers. Does a very good job. The new devices from Tice don't impress me at all.

Both Rotel and Adcom make devices that turn devices on and off in sequence, but the timing is fixed. This can prove problematic if the power amps have large storage caps that take sometime to discharge.

Test the sub by it self especially if your usng the FBD. Sorry I don't use any "calibration" techniques, other than my ears. I do use an RTA to adjust the output level/balance for the mains, this is because they are tri-amped. But L-C-R and rears and sub I do by ear. Also I do what's called "gain riding" during a movie. That means continuously adjusting the volume according to what's happening on the screen. Generally I raise the volume for "dialog" and lower it for the really big effects stuff. This I learned to do long ago to protect the ESL panels, and my ears. It's what the guy at the mixing console at live concerts does.




theAudioWorx
Klone-Audio

[Bing Fung]

Hey Thomas... Nothing to eq the 12SD's? That's increditable. Actually, my single 12 is ok,fine with out the BFD as well, I could live with out it. It's just I find this can add so much more if needed. Very much like a commercial sub now

Given all the transformers in your system, does it hum at times? I notice if nothing in the house is running that I can hear my amp transformers sometimes.

20,000 mF per amp, how can this pose a problem during shut down?

Must be nice to be able to identify what frequency needs the fix. Kinda like the sub mechanic in das Boot, Johan was it? :B That takes experiance. It was funny after I adjusted the filters the first time, I sat back and said damn, I wish I could identify the frequency that needs cutting or boosting. Maybe the more I play with this....

Gain riding? I have to admit, I have done this on occasion as well. Ahh, HT Hi-fi nuts... Nothing is ever simple, even when we try to make it simple, it ends up being complex anyways due to our complex natures.




Bing

[Bing Fung]

Thomas, that is quite the tone generator you sent me, what a nice little program

So If I'm calibrating with only the sub on, what should my reference frequency tone be?

My Denon cuts of at 80Hz for the LFE. How do I integrate the mains with the sub?

Before I had the BFD, I ran VE's test tones for general room level calibration. The required sub level to match the rest of the system was +5 with the mains set to 0. Do I begin calibration of the subs frequency curve(80Hz-20Hz) at that level?




Bing

[ThomasW]

Bing

No EQ, but 6db of shelving boost starting at 25Hz is used on the IB. It functions like EQ but instead of boosting a range it cuts everything above that frequency. It's a kinder form of compensation

Some of the older amps have transformer hum. But all the HT amps are in a power ventilated closet. So they can't be heard.

It's not the number or amount of caps is it's whether or not they are direct coupled that determines if the amps will "pop"

Yea I don't know why more people don't use that tone generator is very easy to use and goes VERY low.

I'd use 100-120Hz and then go down from there. That will give you a good idea as to how the XO is functioning, and probably allow a good match between the mains and the sub. If you just want to test the sub then use 80Hz




theAudioWorx
Klone-Audio

[Bing Fung]

Thanks Thomas...

What about the channel level? For the SPL at sitting posistion, Channel test tones (Pink noise) it wants L,C,R =0, L,R Surr = +1, LFE = +5, moving the meter side to side for the LFE.

It seems logical to me I should level the channels first with the BFD disabled, then begin from there on sub calibration.




Bing

[ThomasW]

I don't think that it's a big deal with the sub on or off. Or with the FBD on or off. That shouldn't effect the other speakers.

As I said, I don't pay any attention to calibration or so called reference levels. I match up the mains, then adjust the effects speakers while the movie is playing. I do this because to my ears there is too much variation from movie to movie for one single setting to be effective.

I do use differing output levels from the sub for music vs HT. The output level is higher for HT. If I leave it at the same level for music it changes the tonal balance, and makes the music sound "chesty". But this level isn't referenced from the pre/pro, it's a level change in the outboard XO output.




theAudioWorx
Klone-Audio

[Bing Fung]

Thanks Thomas, makes sense, for some time I like to boost bass or increase the surounds as well.

Still, it is nice to have a home point that can be reference....




Bing

[ThomasW]

Bing

Here's an interesting link for "dialing-in" subs.
Scroll down the right side to almost the last link. You'll see "aligning and setting up subwoofers"

http://www.digido.com/

theAudioWorx
Klone-Audio

[Julian Data]

Nice link Thomas!




Julian Data
COO of Blackhole Motorsports
http://www.bhmotorsports.com
Revamped DIY www site coming soon!