Live Pro Sound - Is REW Applicable??

[Randall R. Dibble]

Is REW applicable for live sound use?

I have weekend Hobby band and I'm looking for software application such as REW to help with the P.A. System setup and sound management.

What can REW do for me?

I clearly see it's use in my Home Recording Studio and HT sites.

[Otto]

Hi Ran,

What frequencies are you concerned about? Measuring higher frequencies gets more difficult due to comb filtering and room reflections, but you can also use the smoothing feature in REW to help determing wholesale problem areas. If you're concerned more about low frequencies, you should be fine.

Overall, there's no reason that REW wouldn't work for your application. It's just taking measurements of your room. You may want to take measurements in various locations around the room, though. Most of us focus on the "sweet spot", while a few have taken steps to determine averages from different seating positions. I think the averaging approach would be useful, especially if you are working to address the overall response of the room from different points of view -- whether it be the performers themselves, or the throngs of fans!

[Randall R. Dibble]

I am on a fishing expedition here!

I am new to the idea of using software to do what my ears have been doing for the last 40 years. My ears are wearing out and they some help!


P.A. System setup with averaging the Room (area for the dance floor and nearby seating not the entire room) will be the first priority, the second priority is setup of the Subwoofers.

Last weekend we had a show in a club, which measure over 100’ by 150’ but commonly the show is in much smaller rooms. Subwoofer placement is many times are out our control. As bassist being forced send some my signal to the mixer and out the P.A. in order to reduce stage volume I’ve become concerned about getting the best bass sound possible as well as vocals and instrument support. I imagine that my requirements are not as meticulous as a hi-fi or HT setup. I just want to set the EQ for the room Flat (or a House Curve) so that I can EQ the Vocalist and Instruments without GOOFY response issues i.e. three note BOOMY bass which betrays my finely crafted Bass Lines.

Third priority is to help set my crossover points and attenuation for the Tri-Amp P.A. that we’ve assembled.

Thanks for the Help!
Ran

[Wayne A. Pflughaupt]

Welcome to the Forum, Randall!

Will REW work for PA use? Yes. Is it practical? Usually not. The reason is that REW works by “trial and error”: Take a sweep, apply some filters, take another sweep, see how they worked, set new filters if necessary, etc. Most of us spend considerable time – hours, often – using REW to get our subwoofers just right. In a live situation, I can’t imagine anyone having the luxury of that kind of time to tweak the system. What works better for PAs is real-time analysis, which lets you see your changes on-screen immediately as you make them.

I’ve become concerned about getting the best bass sound possible as well as vocals and instrument support. I just want to set the EQ for the room Flat (or a House Curve) so that I can EQ the Vocalist and Instruments without GOOFY response issues i.e. three note BOOMY bass which betrays my finely crafted Bass Lines.

I can relate. REW may or may not be helpful there. It can certainly show you what the system’s doing with the bass, but it can’t show what your instrument and stage rig is contributing to everything.

That last point can’t be ignored. For one thing, unless you’re playing in really large venues with huge PA systems capable of overwhelming the backline, the stage amp can be detrimental to the bass sounding good to the audience. Often it’s too loud, or EQ’d in such a way that it clashes with the PA system. It’s pretty well understood in home theater that multiple low frequency generators are generally a detriment to clean, articulate bass; few associated with live performing – musicians or soundmen – seem to get that. Personally, I don’t even use a traditional bass amp. (Here’s a link to my rig.)

Then there is the bass itself. I consider myself pretty skilled at getting bass to sound good in a mix (as long as everyone on stage cooperates in that effort – more on that to come). But I’ve seen times when I couldn’t get anything but mush from one bass player, yet after a set change the next one would be fabulously clear and defined. Surprisingly, I’ve seen that the price of the instrument doesn’t matter much in this regard!

There are some practical things you can do to insure your band’s mixes enhance the bass as much as possible.

The main thing to avoiding a muddy-sounding mix, where you can’t pick out one bass note from another, is to limit the bass output everywhere else: every other instrument (except perhaps the kick drum), every vocal, and the stage monitors, too. This includes all stage amps, yours included (since your system has subs – it’s a different matter when you don’t.)

The problem here is that the other musicians usually start howling: “My guitar sounds wimpy.” “My toms sound like cardboard boxes.” Everyone likes that full-bodied sound, but as mentioned, too much low freq generated by a multitude of sources is going to give miserable-sounding bass. It’s fine for an acoustic guitar or a male vocal to have deep, rich lows when it’s just the two of them performing alone. But the more instruments you add, the more you have to mix (read EQ) to make the group as a whole sound good, not the individuals. EQ to make each individual sound “rich” and “full,” and ultimately none of you will when everyone’s playing together.

The other thing you can do is get a good analog parametric equalizer and insert it between your house send and the console. If that’s not possible, use the inserts on the bass channel of the mixer. That way you can fine-tune your bass to the room, eliminating any frequency ranges that might be boomy, or weak, etc. I set mine so that I get linear output from the top of the neck down to the bottom.

Third priority is to help set my crossover points and attenuation for the Tri-Amp P.A. that we’ve assembled.

REW can help with that. You can even use the Radio Shack SPL meter as your mic, since REW has calibration files for it. I assume you want to see where to crossover the sub, as most bi-ampable PA cabinets come with crossover the between horn and mids. Just sweep to see where the main speakers roll out, and set the crossover frequency accordingly.

Regards,
Wayne

[Randall R. Dibble]

Thanks for the reply!

The Third priority;

I use a three way crossover (mono) Tri-amped, a power amp for each band (3) of them. Altec 811 horns on top short-flared horn for the mids and a 18” subwoofers. This step of finding the crossover points and attenuation is probability the first thing to do.

How would I start?

Getting the best clean bass sound is going be hard I agree. Multiple sources for low frequency are a problem.

Would delay processor help me (the bass) and the kick drum?

I have tried to explain the issue to other band members but !

Can you point me in the right direction to learn about solutions to this problem?

I just now find the job of soundman for my act has fallen to me.

In the past I JUST played the bass and let the job fall to those knew more i.e. older members of the act. Now I find that I am the senior member and this and many other issues have become my responsibility.

Any suggestions are helpful

Thanks

P.s. I can't use the link to your rig. I haven't sufficient privileges.

[Wayne A. Pflughaupt]

P.s. I can't use the link to your rig. I haven't sufficient privileges.

The problem was on my end – it should be working now.

I use a three way crossover (mono) Tri-amped, a power amp for each band (3) of them. Altec 811 horns on top short-flared horn for the mids and a 18” subwoofers. This step of finding the crossover points and attenuation is probability the first thing to do.

How would I start?

To find the crossover points, just run an REW sweep through each speaker seperately – horn, mid and sub. With the main speakers, make sure they are disconnected the drivers from any passive crossovers, or if they have separate high and low input jacks for bi-amping, use those.

After you get a reading for each driver, notice where the horn starts to roll out. (It will probably be somewhere around 1000 Hz.) You’ll want to set your high pass for about 1/2-octave above the point where the horn starts to roll out. Keep the levels low – maybe 70 dB – so you don’t damage the high frequency horn.

Next, see where your mid starts to roll out at the bottom end. It will probably be around 125-200 Hz. Where it starts to roll out is where you’ll want to set your crossover point between the mid and sub.

Once you have the crossover frequencies set, you need to set the respective levels. REW can help here, too. Take a sweep and notice the lows, mids and highs in relation to each other. If one is really “hot” or lacking, it should show up. When it’s all set right, you’ll probably want the highs a bit lower than mids, and the lows a bit higher than the mids.

Another good way to do the level-setting is to play a pink noise signal through the lows, mids, and highs separately and see what SPL each is reading. Again, you’ll probably want the lows with the highest SPL, followed by the mids and highs.

Would delay processor help me (the bass) and the kick drum?

It won’t do anything for a muddy bass problem, but I have heard that delaying the full system to time-align it with the backline makes a noticeable difference. Never tried it myself, though...

Can you point me in the right direction to learn about solutions to this problem?

You mean the problem of getting the other members to cooperate and dial down all their lows? The only think I can think of is posting a question for suggestions in the Band Management and Performance Forum at Talkbass.com.

Regards,
Wayne