Room balancing - oops - help

[Smob]

Well, I did something the other day that I clearly should not have tried to do. I tried to noise balance our room. After I finished, the equalization was way off and it took us a few ours to straighten it out. I got train on this some time ago, but clearly didn't have the skill to pull it off.

Can someone point me to some instructions and techniques for doing this right?

My biggest problem was the bass end. While I was doing the noise balance, the low frequencies were pulsing high and low every second rather than maintaining a solid level. The only way that I could get rid of it was to almost totally suppress the bass end. Of course, the sound really tinny after I was finished.

[Gracetech]

You are about to step into one of the most opinionated areas of sound so just be aware of that.

Before we jump into techniques can we have a few specifics?

Do you have measuring gear and if so what pieces are you using?

Tell us a little about your system from the console to the speakers. If you don't have make and model info then try to describe the gear best you can.

crt

[Smob]

Give me a couple of days to get all of the makes and models. For now, I'll describe what I know.

Our sound board has a pink noise generator that feeds through the equalizer to the main speakers. There are mids and woofers on each channel. The measuring device has a special microphone that I put in the middle of the room and hooked up the analyzer. The equalizer and the analyzer have the same number of channels and each channel is centered at the same frequency. The analyzer has it's own white noise generator, but I elected to use the board's generator.

The room is about 50'X80' with the main speakers point across the shorter distance.

Considering the frequency of opinionated topics at CMN, I'll hold on to my hat

[Gracetech]

I just wanted to give you some helpful little tips to check everything before you get started. The reason i say this is because you commented that your low end was pulsing(if you had a small variance in the LF section that is normal but if it was bouncing a whole bunch then something isn't right). I'm expecting that something is amiss and you will find the issue by going through this process(possibly).

First find a really long cable. This will ultimately be the one to run to your calibration mic. Then find a short cable and another really long cable. Take the cables(all three connected together) and feed it out of the pink of the RTA and back into it's mic input. Make sure that it's flat and then move on to step 2

Step 2: Step two is take the short cable and plug it into a channel of your console and make sure the eq is flat or defeated and then plug the other two from the output back into the RTA. Check and see how flat it is. It's probably going to be a bit off but this is to be expected. If it is way off then post back and we'll take a closer look. After this is done lets move on to step 3.

Step 3: will be to feed through the eq like you did the console. After you have checked the eq and are happy with the results then you can connect from the RTA pink through the short cable through the console and then with one of the long cables into the eq and then out of the eq back into the RTA. We should be through the entire chain minus the amp and speakers but if we are not we need to add a cable and step for each additional piece of gear to the equation.

Now that you have finished testing your gear and you have made notes of the final outcome, go ahead and hook up the system with your regular cables. Then take the final output before the amps and feed it back to the RTA with one of the tested cables. Check this result against the final outcome from earlier. If everything looks the same then we have at least ruled out the majority of issues in the gear. At this point you should be ready to tune the speakers to the room.

BTW: I do this for all the systems i setup so that the interaction between gear is checked for any anomalies.

Also what speaker configuration do you have setup? Stereo? Mono? Cluster?....

crt

[waynehoskins]

And are there subs?

One thing that popped up to me is the measurement was made in the middle of the room. If it's a stereo rig, we may be dealing with a bass power alley at center making the measurement off down there.

Or not, who knows?

Among everything else, I'd consider attempting the measurement with an identical setup with the mic at a different location if all the gear measures OK.

I tried using our DRPA's Auto Pink The Room routine when we first got it .. never liked the results. Probably part of it is that I didn't have Their Mic, that may well be a big part of it. After futzing with it for a couple of hours I flattened it out, tuned it by ear in a couple of minutes, and called it done...

It's also possible that in Bob's case the mic was either out of, or obstructed from, the horn pattern, that might account for it too. But there's not enough to tell.

[cjlowe]

Just a quick tip - don't forget to put the measurement mic in several spots around the room. You might have a bass trap somewhere or something.

[Smob]

Great stuff so far. I will get to the equipment tonight and find out as much as I can about what I have.

Wayne, there are subs.

Chad, I think I have the idea of what you want me to do. Basically, check out the rig one piece at a time. I will have a little problem getting started as the measurement mike is integrated with its cable. That will prevent me from check that cable in the loop. I will get more specs tonight.

I did the eq while the mike was in the center of the room. Yes, we are running stereo and I think a bass trap is highly likely. When I get back to making the measurements I'll try some different spots in the room to see what I get.

[Smob]

Well, so much for the amateur trashing around with this. Our leader is going to bring in a professional to balance the room. As much as I love learning to do new things, I think I pushed the limit this time. Getting someone in that knows what they are doing is best. Thanx for all of the help, though. I hope I have the opportunity to shadow the person doing the work. I'll let you know what happens.

[Smob]

If you're interested, we had a professional in yesterday and he found (1) that the mids on the left side were reversed phase, and (2) the cross over had the high end cross over too high and the low end cross over too low, so that the mids were doing all of the work. After those two adjustments and flattening the eq out completely, the system sounds great. We will see how it goes this Sunday.

[Gracetech]

wOOt!

It probably is a good thing a pro came in, it might have taken a while to sort out those issues. Be sure to tell us how it goes.

crt

[Smob]

The sound was much better today. Maybe a bit to crisp, but that can be sorted out. I think we are down to minor tweaks. Whew!

[Gracetech]

Did you flatten out your channel E.Q.'s?

Good to hear things are moving in the right direction.

crt