Setting up Bx5a's in editing suite
 

I just purchased a pair of M audio BX5a's and a Behringer xenyx502 mixer and was wondering how to go about setting them up for accurately mixing and controlling audio. Whats throwing me off is the volume knob on the speakers. If there is a link or anything someone could give me that would be great too.

James... not really enough information. What is the main purpose for this set up??? Recording??? Playback??? If so, to/from what type of a device: computer or digital recoder???

It's just going to be for my editing suite, I apologize that I wasn't clear about this earlier. It is going to be used for mixing my final projects. I obviously don't expect great results of course but when I set the mix to 0 on the board everything is extremely loud even though I am fine on the audio tool in FCP. The volume knob on the speakers is in the middle.Today I will just set up some bars and tone and set it up by ear by having everything at unity on the mixing board and then just turning down the knobs on the speakers and judging by ear. Is this okay or completely defeats the purpose of having a mixing board?

There is a process for calibrating monitors for the mix. You'll need to pick up a sound pressure meter, doesn't have to be expensive. There's an analog meter at Radio Shack for about $45 that's perfectly acceptable (and better than the $50 digital version for this purpose.) You also need some mono calibration tones - a 1kHz sinewave at -20dBFS and a pink noise tone at the same RMS average level. I don't know FCP but the necessary tones may be available in the software. If not, the CD for Jay Rose's audio postproduction book has the required tones or if you can't find them anywhere else, drop me an email offline and I'll be glad to generate a pair and email them back to you.

The process is to first load the sine wave (mono remember?) into FCP and first for the left and and then the right channel, adjust the output level control until FCP's output meter reads -20dBFS on each channel. Position the sound pressure meter where your head will be when mixing. Swap the pink noise tone for the sine wave - the meter will now be considerably higher than -20 but don't worry about it, don't touch FCP's controls. Send the pink noise to each channel, one at a time, muting the other channel. Adjust the volume using the speaker volume knobs until the SPL meter reads 80dBSPL for each speaker by itself if you're mixing for DVD or broadcast, 85dBSPL if you're mixing for theatrical release. Mark the controls on the speaker with tape or a dot of nail polish so you can ALWAYS set them to the same spot for every mixing session.

That is exactly what I wanted to know. Thanks and I'll send you an email right now.

Steve, that was a great explanation. I'm going to calibrate my BX8As tomorrow, this is exciting.

One question though, you're referring to adjusting the volume control on the amp section of each individual speaker, but what should I set my Monitor Volume knob on my Mbox 2 Pro interface? Should I also set that at a specific point, and nail polish or sharpie that spot as well?

Thanks,
-D

Well don't make "rules" needlessly and become a slave to them. Maybe it's just me, but I don't mark my knobs. I usually set the monitor gains to a comfortable spot and go for it. As long as I know what "loud" is, I'm fine.

Besides, the human ear is not linear. It is not as sensitive to highs and lows at low levels. Google Fletcher Munsen Curve for more info. If you only mix at low levels you may not eq properly. I listen at low mid and high levels as I work on a project to make sure I'm not missing something.

I think my power amp is set to 3 (out of 10). When I turn the monitor out control up on my Digi 003, it's plenty loud. I can't even turn it up all the way. It's too loud.

Regards,

Ty

Is there a detent in the center of the Master volume control's range? If not, mark it in some way so you can always return it to the same setting. The idea is that you'll always be able to return everything in the chain to a known, predicatable level. My own setup uses an Echo AudioFire 8 interface which doesn't have any hardware level controls other than trim on the two mic inputs. Its output level control is on the software control console and acts as an attenuator for the playback in the digital domain - no sense throwing away bits so I leave it at full output. Normally I take a pair of analog outputs from the interface to the Aux 4 stereo input on my Mackie 1642 board which are routed in turn directly to the Control Room monitor outputs. The Aux 4 input's level control has a detent for unity gain and although the Control Room output is a conventional volume control, it too has a centre detent position so it can always be returned to the same setting. That leaves the final volume setting to my JBL LSR4328 monitors. They have digital signal processing and its room correction setup processing trims each speaker's amplifier so they have equal sound levels at the listening position. Their level control is a master system gain which adjusts both speakers together. They have meters on their front panels that indicate the system gain when adjusting their master volume control, as well as displaying the output signal level on each channel when listening normally. I leave the interface software level control full up so there's no attentuation, put the Aux input at unity gain and the control room monitor output volume to its centre detent, and then adjust the speaker's gain while noting the setting that gives me the desired reading on the sound pressure meter. By centering the knobs and setting the speaker gain indicator to the same numbers using the speaker's own volume control, I can always return to the same exact system setup.