Subwoofer Myths And Facts

[lanman31337]

I've seen a lot of "rumored" information, and I've seen some very false information as well. I wanted to clear some things up for some people.

1. The #1 thing I hear all the time is underpowering subs will blow them. I'm throwing the BS flag way high on this one. If this was the case, you'd have to play your subs at full tilt below clipping or not at all, or else every time you turn down your volume, they'd blow.

2. You DO NOT have to run both voice coils for a dual voice coil sub. Same goes with all four on a quad coil sub. Your power input would have to be halved since you're running a single coil, but it won't melt or blow. You can then put a variable resistor on the second coil to change the sound of the sub, but I'll let you do some research on that. Here's some light reading - http://www.geocities.com/f4ier/dvc.htm

3. "My sub is rated for 500 watts and I put 500 watts into it and it blew" First thing to ask yourself - are your gains set properly? If not, then there's your problem. Woofers fail mainly because of one of two things - mechanical and burnt coils. Burnt coils usually happen when you put way over the rated wattage into them, and mechanical if the cone exceeds the max excursion. If you'd put an ampprobe around your speaker wires, you'll notice they push some amperage. The coils can only handle so much amperage. When you are clipping, you're peaking way beyond the 500 watts, and pushing a dirty signal at that. One byproduct of amperage is heat, and when it gets warm enough, your speakers start to smell and let off magic smoke.

Questions, comments, concerns, ask away.

[Forevrbumpn]

2. You DO NOT have to run both voice coils for a dual voice coil sub. Same goes with all four on a quad coil sub. Your power input would have to be halved since you're running a single coil, but it won't melt or blow. You can then put a variable resistor on the second coil to change the sound of the sub, but I'll let you do some research on that. Here's some light reading - http://www.geocities.com/f4ier/dvc.htm

I didn't go to the Geo cities website, but when I worked for my old boss, who had 30+ years in the business of engineering subs, he did say that running 1 coil, not the other will kill the coil, I couldn't understand that?

But from how he explained it was that the wire is expanding at one rate, while the non used coil is only tranfering heat, and what happens is usually a slinky issue with the coil, glue ends up failing on 1 coil, but not the other

[lanman31337]

If your sub is rated at 800 watt rms for 2 coils, only feed the one coil 400 rms. You won't have a problem with heat.

[Forevrbumpn]

not really, its the glue expansion that holds the wires together

1 coil getting hot, the other not, there is issues. I have seen it happen myself, when I started working in the warranty dept, I had to take care of customer returns on speakers. When the customer returns, or the installer takes the sub out, they have to note how its installed

nothing to do with the halving of power, trust me.

[bkolfo4]

You see driver failures with one coil running because someone tried to run full driver power to that one coil.

If you can't run one coil at a time, someone better let Kicker know the Warhorse is junk. It runs one coil at a time.

Which is another good point. Amperage does not kill the coil. Power/heat kill the coil. The wire in a sub coil will have a maximum threshold for current, but it will normally be beyond the thermal power handling of the sub.

Once again, look at the Warhorse. It runs one coil at a time at full power. If the driver can handle 2000 watts, the warhorse will hit EACH coil with 2000 watts, but it does it one coil at a time, so the continuous power dissipation is the same. ie, 5000 watts per coil continuous is equivalent to 10000 watt per coil when only one coil is run at a time.

I just had a long conversation with Scott at Fi about all this 2 weeks ago, as I am thinking about getting a couple of warhorses

Brian

[lanman31337]

The coil is not going to get hot if 1) you're not clipping and 2) you're not going over the thermal limits. In the example I used with the 800 rms dual coil sub, if I set my gains correctly for the single coil, I can wang on it all day long, every day with 400 watt rms. Only once you start clipping will you start pushing more amperage and more heat.

[bkolfo4]

Clipping is ok as long as you do not go past the thermal limits. . .

Clipping does not cause more amperage. It holds the voltage/amperage at a DC like state during the duration of the wave being clipped. This increases the RMS power at the maximum voltage. Increasing the RMS power increases the heat.

Some people also say "holding" the driver in place reduces cooling, but that would be some CRAZY clipping to actually hold the driver in place long enough to affect the cooling. Maybe with a long burp or test tones, but more than likely not music. . .

[dwz]

I thank you for posting this thread... I believed all three of these myths especially when I posted a thread yesterday about blowing a second type-r ! Thanks lanman

[dwz]

Googling "blow a sub" or any variations of those will lead you to find a ton of those same myths being passed around.

Here's an example

http://forum.dvdtalk.com/archive/t-499576.html

"Well to clarify terminology, "blowing" the sub would mean to overdrive the speaker. "Clipping" is underdriving the speaker and will cause damage.

Either way if the mismatch is too great you will damage the sub and possibly even the amp."

and

"Let's put it another way: Blowing is overdriving the speaker. Clipping is overdriving the amp, which damages both amp and speaker.

Yes, you should be fine for normal use, keeping it within its range."

LOL

[lanman31337]

You're exactly right. It'll turn the elliptical sine wave into a square wave. I also thought that when you are clipping, it actually peaks and valleys greater than it would if you had a clean signal instead of a clipped signal which would add amperage and heat.