Active sub-woofer?

C

Calwood

New member
Hey everyone. I'm looking at active sub-woofers. I want to use one with my Alesis point 7 monitors in the studio. I want to see if it helps with my mixing.

One thing,...do you guys feel like this is a good idea?

Another thing,..The sub I'm looking at (M-audio) has xlr outs for monitors and a sweepable crossover frequency. Does this sub power my monitors as well? Or do I route the sub to my power amp then to my monitors. This is getting confusing.
Here's a link to the sub I'm looking at.
Thanks for ANY help.

http://www.americanmusical.com/st/aspx/i-MII+SBX8/en/item.htm
 
The outputs should go to the power amp that drives your monitors. Typically the crossover should be set at least one octave above the lower cutoff of your monitors.

My issue with your plan is the sub itself. It's hard to imagine that a single 8" sub is going to give you any performance enhancement whatsoever. If you look at the specs , they don't even tell you the low frequency limit of this "sub". If it actually does go down much below 40Hz, it does so with a huge amount of distortion and boomy resonance. Personally, I wouldn't waste my money on what looks to be a glorified computer speaker sub.

Thomas

---------------------
Barefoot Sound LLC.
Recording Monitors
San Francisco
 
Thanks for the reply man. Now i know another thing to look for,..."the frequency limit of the sub".

I think I'll do some more research before making a choice. Thanks alot man,..really.

Take 'er easy,..
Calwood
 
No problem.

You do have to look at the specs, but you also have to think about whether they make sense or not. If an 8" sub says its lower cutoff is 20Hz, you should be extremely skeptical.

In order to reproduce low frequencies with any semblance of accuracy you need to move a large volume of air. This means a large speaker and/or a large linear excursion. Besides maybe one bizarre and very expensive little unit, I don't know of any 8" drivers that are capable reasonable subwoofer performance. There are good 10" drivers available, but even then I would strongly recommend using a pair. And they shouldn't be going down to 20Hz either. 35Hz is a more reasonable cutoff for a 10" sub.

A good sub should not only extend your low frequency response, it should do it with reasonably low distortion, and it should also have enough high frequency extension such that it relieves your monitors of some of their low frequency burden. This way your overall system is truly enhanced. Unless you have some very sophisticated design like a Velodyne servo, a single small sub is just not capable of delivering these performance characteristics.

Thomas

---------------------
Barefoot Sound LLC.
Recording Monitors
San Francisco
 
The nominal frequency response of an M-Audio SBX is 30-180hz. I actually own this puppy, which I use with a pair of SP5B's. The SP5B's bass ports are in the rear, because they were always intended to work with this sub. It was formerly called SP 8S, same sub, different cabinet. It was designed to work with a pair of powered sattellite speakers, but you could, as Barefoot suggests, route the XLR outs to the power amp if you use passive mains.
It may also be true, as Barefoot suggests, that if you have a good balanced pair of mains, the SBX would not offer an improvement in overall sound quality, quite possibly the reverse. That being said, if you use M-Audio BX5's/ BX8's or SP5B's/SP8B's, the addition of the sub *does* dramatically improve the sound, and makes mixes translate a hell of a lot better. Would I use it with a big mucking pair of Genelecs? No. Would I use it with a pair of SP5B's?- absolutely. The whole setup may be cheap, and yes I know they are bottom feeder moniters, but the combination works very well if you are used to it, and can produce perfectly good mixes. That is what matters, IMHO. Before I added the SBX, I used to play my mixes in the car and get my head blown off by too much bass. Now the mixes translate quite well.-Richie
 
Yeah, if the sub is designed to work with those specific monitors, then I image it's the right way to go.

30Hz? If that's true, I bet the harmonic distortion components are louder than the fundamental! ;)

Thomas

---------------------
Barefoot Sound LLC.
Recording Monitors
San Francisco
 
Hey barefoot,.....

Youve got me thinkin' now man. Thanks ALOT for the info. I feel much more informed now. This is all still a learning expierience. Thanks to people like you it is an enjoyable expierience.

Thanks alot brother.

Richard Monroe,...
Yeah,..I'd have to agree,....that sub was made for those speakers so it is not surprising that it works for them. I have a pair of point 7's. They really arent that bad,..I've had them for years and can get most of my mixes to translate well,...but,...when I'm mixing I have to mix bass light to compensate for the monitors. I was thinking that if I add a sub,..I could get more creative with my mixing without always thinking about compensation,..ya know.
Thanks for your input man.
 
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