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After recent comments on the article, I’ve decided to respond to a couple of those and to discuss subwoofers. Subwoofers are critical for creating certain audio atmospheres and for having an efficient use of power for the low end of your program material. However different subs have different characteristics and their performance is highly dependent on placement.

First of all, to quickly reply to a couple of comments, I’d like to tackle the all in one cabinet design. As convenient as this may be, it may not be the best choice sonically. Here’s my reasoning. Though the dual 15’s have great low end output, they can’t move as fast as a 10” or 12” woofer to accurately reproduce the critical midrange which is where most of your vocal range is. This is why a 3 way box with a subwoofer performs very well for vocal groups. For instance, I’m looking at purchasing a 3 way box with a 1” horn, 6” midrange, and 12” horn loaded woofer. This is a very ideal package and is highly accurate in reproducing vocals. Also, with an all in one box you can’t get a very good height out of them, thus sometimes having very different levels between your front and last rows. However, you can achieve a very good sound with a combination box and it certainly does cut down on cost of the actual cabinets and amps. This is a very economical way to go.

Now the part about the delay and phase and time alignment is true. However, it has been my experience that this is not as much of a problem with some of the new powered speakers that are out. Most people would not be able to sit in the audience and say “those speakers are out of phase or need to be delayed.” However with credit to the reader, it does affect the over all frequency response and can make it difficult to EQ if the system is out of phase or the drivers are not at least close in alignment. But don’t let this worry all of you who have separate subs and top speakers. Simply try to keep your subs as close to your top speakers as possible and you should be okay. And this is what we are about to talk about.

Subwoofers provide the “meat” of a sound system. They can make or break a bass singer. First let’s look at what kind of subs are out there.

Picking a subwoofer can be tricky. 2 main things to look for are the continuous and max SPL output and usable frequency range. Wattage is not everything. Wattage simply tells you how much power that speaker takes to reach a certain output level. The more efficient sub is going to have a higher output at a lower wattage. This means you use less power. Frequency response is a little trickier. Make sure you look for the usable range. For example 40hertz to 120 hertz would be average. However I would not get a sub that doesn’t go at least down to 40 hertz. This will produce most of the signal that your audience will be able to hear.

So should you get a single 18 or a dual 15 or a single 15 or dual 12 or what?!?! Well, I have to admit, there is only one brand that I would use a 12” or smaller woofer for my subs. That said, I prefer 15” subs and even more than that, dual 15’s are great (IMO). I currently run 2 single 18’s and they can get a little out of control and sound boomy. This is very characteristic of 18’s. Again, the smaller the woofer the faster it can move, providing for a tighter sound. Not to say I’ve not heard a tight sounding 18 but they’ve had a good amount of processing and they were high end boxes. Picking the right sub cabinets also depends on your program material. For instance, if you are a trio and you just use tracks, your low end can be produced very easily by a single 15. However, if you are a quartet with say drums and bass guitar and piano, you’ll need something a quite a bit beefier.

Dual 15’s are my favorite. It gives you the tightness of the smaller 15, but will reach down low to reproduce in the same range as an 18, but with a much higher output. It’s the kind of bass that will hit you in the chest and leave a bruise if you want it to! Single 15’s are a great alternative if you can’t afford or pack a dual 15. This is a major reason why most powered subs are 15’s.

Placing subs is really quite easy. Placing the subs directly in line with your top boxes is the best, because they should be delayed a little if they aren’t lined up vertically. However, it won’t be the end of the world if you can’t match them up every time. Also, some powered subs have a phase switch, which in my experience works very well. Buying speaker systems that have built in processing or an outboard processor with presets for the particular speaker you have can take care of this as well.

Here’s the kicker. The very best place to put your subs, if they don’t end up too far in front of the main speakers, is to pack all of them smack dab in the center(on the floor of course). Here’s why. Lower frequencies cancel each other out very easily because they are not very directional. When you have them separated you’ll have lines of low end. If you looked at it through a computer program, it looks like pin stripes through your audience. This is another good reason to have separate subs. When your low end all comes from the same place (in the center), the low end is evenly distributed from the same source. This eliminates hot spots and dead spots when it comes to your low end. Essentially they work as one single cabinet and dispersion is very even plus you gain an extra 3 to 6 db worth of low end. So of course this is especially useful when you’re in a venue that’s really too big for your system or for outdoor venues. I myself realize this is not always possible due to most of the venues we play in this industry. But every time I get the chance to I will place my subs as mentioned above.

I hope this helps some. I’m sorry, I have not gotten word of any workshops at this time. However, I am going to go ahead and recommend some magazines to subscribe to. Just look them up on the web. I will also answer everybody’s question to anything audio…Read the Yamaha Sound Reinforcement Hand Book if you want to learn live audio. The below magazines are great too, but I read the Yamaha book almost as much as my Bible.

Pro Audio Review
Live Sound
Church Production
Pro Sound News
Sound and Communications

See ya’ll on the road and keep those emails comin’

Josh Hoevelmann

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