Sub Woofer Questions

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MERRICK

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I have two 3 way monitors which have 3" Tweaters, 4 1/2" mids and 8" woofers. They were assembled by me and sound really good. I am thinking of adding either one or TWO subwoofers to my set up for mixing. I have heard a particular horror story which required a 20,000 CD recall because the music was not mixed/mastered on a subwoofer (don't ask me where I heard this, can't remember). Now the questions:

1) What is the opinion of using subwoofers for monitoring?

2) Should I install switches to activate inline crossovers to limit my 8" woofers to e.g. 80~100Hz and adjust the Sub woofer crossover accordingly?

3) Is there an advantage/disadvantage to using two sub woofers in a stereo monitoring set up?

4) Any and all input welcome

:)
 
I was a mastering engineer for 10 years and I've never heard of a sub woofer in the mastering studio. Our Urei mains did have 12" cones in them though... The mix and edit guys in the room next to mine used a sub occasionally just to check a mix against, but they never mixed using a sub. They had 2 12"s in their mains. What was the CD that got recalled?

In my opinion, subs are for pleasure listening... not for crucial mixing or mastering. Check against them, like you would anything else though... boom boxes, tv, car stereo, etc.

As far as 1 or 2 subs go, bass signals are non directional. 1 or 2 makes no difference. If you decide to use one, I highly suggest tuning your system with a freq. analyzer so that you're not getting more bass than what's really there. Or your mixes will sound bass weak. Also, be careful of placement because you don't want to create standing waves and weird phasing problems.

Some other things to consider are coupling effects in relation to the floor and the distance of 2 woofers in the same enclosure. 2 10's close together can outdo a single 15. They "couple" and create more surface area that way. More air volume gets moved.
Having them on the floor also couples.

If you're going to make the subs yourself like your other speakers, are you familiar with speaker enclosure constuction and tuning? You'll also want to take into consideration how a sub will act with your current system. I have these cool little plugs for my home monitor port holes when ever I use a sub.
 
Beware!

Subs majorly boost low frequencies. by all means use them to check later, but don't mix with them. a true sub woofer is designed to play frequencies below where a regular woofer rolls off, but subs are mainly used to boost bottom end. if you mix with them, what sounds like a good amount of bass will be weak on other systems.
as for the cd recall, its possible that the mix contained a lot of bass around the 20-30 hz mark, which can damage some speakers but will be inaudible on most.
An example I can site is a film I produced. The sound mixer mixed it on an akai home stero system. sounded fine on that. he also used sound effects CD's. there was a track of thunder that he used that had a lot of deep bass in it. his little akia system didn't go that low, so he boosted up the bottom end on it.
the film went of to a festival, and the screener copy was played on a tv (with horrible tv speakers), and the film was nominated for a sound design award. At the festival, the film was screened on a full blown cinema speaker set up that went very loud and deep. when the thunder came on, the boosted deep bass nearly caused the speakers to crap out, and the result sounded terrible, ruining the climax of the film. needless to say, it didn't get the sound design award.
the moral, check the mix on several setups, and beware of too much bottom end. weaker bottom end will be better than if it causes distortion on some systems.

-Dr_Sbaitso
 
Thanks For the excellent input. I'm sorry I don't remember the name of that recalled CD etc. I saw the article at a time when Mixing considerrations were still in the future for me.

I'm sure I'll be getting at least one sub but as far as mixing on it, three's the charm and another independent source has confirmed what you both have said. So I'll use it (sub) for checking final mixes only.

Thanks again!
 
The more answers, the more questions...


A drummer friend of mine records double kick drums and said that on one cut he played the same pattern on both feet and paned the two tracks hard left and right.

It got me wondering...
If one was to have hard panned L & R low frequency material (kick drums dobled synth bass lines etc), would it be revealed in stereo sub woofers?
 
If one was to have hard panned L & R low frequency material (kick drums dobled synth bass lines etc), would it be revealed in stereo sub woofers
Click to expand...

the ear can't distinquish direction with low frquencies (below 100hz) which is why you only need one sub. I think subs are a good idea. (note all the major manufacturers offer them) I had URIE 813s and they had a sub but it was from around 250Hz down so there were two.

It appears to me that the person who had the problem with all the low end ruining his film SHOULD have used a sub.

If your monitors don't go down to 30 - 40 Hz (NS10s don't) then you should add a sub.

cheers
john
 
Although the majority of the kick is sub freq. range and will be relatively non-directional, the beater sound isn't. Effective EQ could give L-R kick sounds.
 
OK, I'm definitely pro-sub... just get that out right away... :D

The purpose of a good subwoofer is to EXTEND the low frequency extension of a system. It has nothing to do with BOOSTING anything! That's what the "superbass" button on a boombox does.

I think it essential for mixing, as without it you really have no idea what kind of subsonic content your recording contains. You're just guessing without it. Would a photographer develop his prints without the color red?
A classic example of this is the Eric Clapton unplugged album. When listening on a properly balanced system with a sub, (or through headphones) you can hear a huge T-Rex like WHUMP! WHUMP! WHUMP! as he taps his foot! Is that realistic? The engineer apparently didn't realize it was there, thus marring an otherwise excellent recording.

Yes, most consumers don't have subs (or good ones at least) so what do you do? Well, test on other systems of course!

It will make a huge difference if you have two versus one sub. In most cases, one sub is preferrable to two. If you must have two for output reasons, they are generally located right next to each other. The main reason for this is to reduce the room modes you have to deal with. When you're dealing in the pistonic range where the wavelengths are significant compared to the room dimensions, the rules change a lot. Subsonic bass is largely non-directional, so the best place for the sub has little to do with imaging and everything to do with smoothness of response. Sub Placement is a topic that could fill volumes, so I won't go into it here...

As a side note, I should mention that most subs have a lot more higher-frequency components than they should which makes them more directional than they should be. This can be due to a too-shallow crossover slope, distortion, port noise, etc etc...

Merrick, to address point (2) I would highly recommend an active crossover. Passive crossovers operating in the low-bass region are real messy and lossy. The power involved at these frequencies as well as other factors like complex driver impedance really makes it rough. Active works much better. Check Marchand Electronics for some truly superb crossovers available as kits. (or assembled) http://www.marchandelec.com/
 
Apologies for my earlier post. I mustn't have explained what I meant.

Yes, a true sub woofer should extend the frequency below what the woofer does, not boost it. however, the majority of people that buy subwoofers from my store are using them in a home theatre setup, and will essentially use it to drive the bottom end and exaggerate it. for music this is not desirable but in a movie this is, as it gives more impact during explosions and the like.

A sub setup properly should be nigh on inaudible when the main speakers are switched off. This is assuming that the main speakers go low enough ofcourse. what you want for monitoring is the closest to a flat response you can get.

Yes, the sound mixer on the film should have tested on a sub, and he would have realised his error. every system is different, and you need to check on many to make sure the mix sounds good on most of them.
 
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