Subwoofer Myths And Facts

[OBI]

If he had the volume at 1/4 most of the time, that's running it under rms.

True. I just remember hearing that about the MT's once not entirely sure if its true or not.

[finkster]

I always knew it was bullshit when they said that a sub needed more power to "cool itself" on certain models....That made absolutely no sense, because the more power u have the more heat....

[lanman31337]

There is so much I could say to that, but I will let you believe the way you believe. We would never get anywhere

I'm going to say it. I'll take one for the team. I'm going to throw out some random numbers too, but they'll go along with this. Ok now everyone huddle around the campfire.

For your 300 watt amp, let's say your AC voltage needs to be 23. That's a nice even number.

For your 600 watt amp, let's say your AC voltage needs to be 40. Another nice even number.

So I hook up my 300 watt amp and I'm listening to a little something something, and I've got my volume at 3/4 and my subs are seeing 23 volts AC.

I swap amps out, get the gains set again. Now I'm running the 600 watt amp. I turn the volume to let's say 24 out of 40. My subs are seeing 23 volts AC. Same exact as the 300 watt amp. SAME EXACT!!!!! There won't be any sound change (unless the quality of the amps are night and day) and the 300 watt amp is pushing the subs just like my 600 watt amp is at the volume. There is no minimum that subs need to push a mighty cone or a whimpy cone.

[bkolfo4]

. . . .(unless the quality of the amps are night and day) . . .

Box designs, amp quality, type of sub (BL curve is a good parameter to look at, since BL drops as the cone moves toward Xmax), what else??

[lanman31337]

Now you're getting all technical and making peoples' brains hurt. And they don't know why!!! Too many variables, not enough time.

I'm Jeffrey by the way, nice to meet you.

[Ben Building]

I'm going to say it. I'll take one for the team. I'm going to throw out some random numbers too, but they'll go along with this. Ok now everyone huddle around the campfire.

For your 300 watt amp, let's say your AC voltage needs to be 23. That's a nice even number.

For your 600 watt amp, let's say your AC voltage needs to be 40. Another nice even number.

So I hook up my 300 watt amp and I'm listening to a little something something, and I've got my volume at 3/4 and my subs are seeing 23 volts AC.

I swap amps out, get the gains set again. Now I'm running the 600 watt amp. I turn the volume to let's say 24 out of 40. My subs are seeing 23 volts AC. Same exact as the 300 watt amp. SAME EXACT!!!!! There won't be any sound change (unless the quality of the amps are night and day) and the 300 watt amp is pushing the subs just like my 600 watt amp is at the volume. There is no minimum that subs need to push a mighty cone or a whimpy cone.

I agreed with your first post, but this seems to be a thread dedicated to the electrical limits of a voice coil and not the mechanical limits.

On that point, I think it might help to think of things in terms of physics. Whenever one allows electricity to flow through a conductor (i.e. coil wires), heat is generated because that is what makes a conductor a conductor. Electrons moving causes heat and there is nothing one can do about it.

A voice coil is just one loooong wire glued to a tube-shaped former. So far, technology has changed the process, but not the concept to a significant degree. The more electricity, the more heat. Glue, copper and aluminum can only handle so much heat before they start to melt or burn. Pushing a sub with less than RMS power (assuming it is CLEAN), is not going to blow your sub, electrically speaking. Mechanically, maybe depending on the application, but not electrically.

[littleitaly1990]

I believe that it is plausible to believe that for most subs, underpowering subs won't damage them, but for some (lower quality or a unique design) it can. My graph sorta shows what I'm trying to get at here, and why I always believed that it MAY be possible for a sub under RMS without clipping to blow due to thermal problems. Alright here we go. As you give a sub more power, it moves more, and thus, cools more, as shown by the graph. However, is it not possible that for some subwoofer designs, there may be a section on the graph where it doesn't move enough to cool the sub at that particular amount of power. Keep in mind, the graph is anything but linear, which is where all those technical terms come into play. I am no expert, but I can see why some people truly believe it is possible to damage a sub due to underpowering.

[Ben Building]

I believe that it is plausible to believe that for most subs, underpowering subs won't damage them, but for some (lower quality or a unique design) it can. My graph sorta shows what I'm trying to get at here, and why I always believed that it MAY be possible for a sub under RMS without clipping to blow due to thermal problems. Alright here we go. As you give a sub more power, it moves more, and thus, cools more, as shown by the graph. However, is it not possible that for some subwoofer designs, there may be a section on the graph where it doesn't move enough to cool the sub at that particular amount of power. Keep in mind, the graph is anything but linear, which is where all those technical terms come into play. I am no expert, but I can see why some people truly believe it is possible to damage a sub due to underpowering.

This may seem obvious, but Root Mean Power (RMS) ratings are the MOST power the manufacterer recommends for that sub. This is a combination of the Mechanical and Electrical limits of the subwoofer. When you speak in terms of a sub moving X distance to produce Y cooling, keep in mind what is causing that movement in the firs place: ELECTRICAL POWER (Faraday Induction, actually, but that's besides the point). Flowing less current through a wire makes LESS heat not more.

I really think certain manufacterers claim this because they want to sell you a big, high-priced amp to push those subs. Clever marketing, I think, but not plausible physics.

[cc_audio]

Ok, why in the hell would you ever want to run one voice coil of a subwoofer? If you have a dual voice coil woofer get an amp that will match impedance with BOTH coils wired. If you really like your amp, then get a subwoofer with coils that will match amps stability when wired. Both coils ARE SUPPOSED to be connected. If you want to hook up one get a Single voice coil subwoofer. That is the most retarded myth ever. There is no good reason to connect only one voice coil. If you do and it doesn't blow, then you have a tough woofer, but its still not good for it. Connecting one voice coils causes problems PERIOD...regardless of what you woofer is doing. There's too many options available that make wiring one voice coil impractical. Don't do it!

If your sub blows due to underpowering then you're doing something wrong or you have a shitty driver. Underpowering a woofer will not make it blow. The whole MT thing sounds like a hint in selling bigger amps. I doubt you could blow an MT by underpowering it. If you could there would have been all kinds of stories about that problem when that driver was super popular.

[bkolfo4]

I believe that it is plausible to believe that for most subs, underpowering subs won't damage them, but for some (lower quality or a unique design) it can. My graph sorta shows what I'm trying to get at here, and why I always believed that it MAY be possible for a sub under RMS without clipping to blow due to thermal problems. Alright here we go. As you give a sub more power, it moves more, and thus, cools more, as shown by the graph. However, is it not possible that for some subwoofer designs, there may be a section on the graph where it doesn't move enough to cool the sub at that particular amount of power. Keep in mind, the graph is anything but linear, which is where all those technical terms come into play. I am no expert, but I can see why some people truly believe it is possible to damage a sub due to underpowering.

Two problems with that theory -

1. Most are talking about "underpowering" as using a 200 watt amp on a 1000 watt speaker. To the speaker, if it is getting 200 watts, it does not know if it is from a 200 watt amp or a 1000 watt amp.

2. Your point is actually valid, but is really a different situation. It would more than likely only occur if you were playing a test tone at a frequency where excursion is a minimum due to the box design (like an SPL burp). I don't see it happening very often with music. If it does, someone may have cheated on their thermal power rating.