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Old 9th April 2019
  #165
Here for the gear
 

Quote:
Originally Posted by lechszcz View Post
So whats the max DB that can blow a 15" speaker?
Depends on the physical construction of the woofer and box and the quality of the signal being played.

A properly designed folded horn cabinet with a high quality, high spl ( high efficiency per watt) subwoofer can exceed 140 db(loud as gunshot, point blank range) at 200 watts rms/ 400 peak without blowing, given the speaker is properly designed physically, the cabinet is the proper size for that particular woofer, and the amplifier is producing an undistorted signal.

200/400 watts is relatively nothing. Ive seen a subwoofer that had NO rms, max, program or peak rating, because the designer hooked the prototype up to a 20,000 watt monoblock that he had designed to accompany it, and he couldnt manage to either blow the speaker, or peak out the amplifier.

Db, sound pressure, is all dependent on the area that is being filled with sound. Ive never heard a single 20,000 watt sub, but ive been in a 12,000 seat arena where the system had about 20,000 watts going through about 16 subs, and, as huge as that arena was, when the bass dropped, it was at least 135 db in the bass, way out in nosebleed. Db drops by 6 db, or fourfold, every time you double the room size, i believe. Now if that arena was easily 50 times larger than a movie theatre, those 20,000 watts that were hitting 130 in the arena, would exceed 400 db in a relatively smaller movie theatre.

. 20,000 watts would be that super unblowable, ooak woofer.That would likely be lethal to anyone present, as a mere 160 causes complete hearing loss and intense physical pain already. At 400db, even if it didnt squish your innards, or stop your heart, it would make breathing impossible, and anyone would suffocate- at the least.

Please correct me on the formula relating sound pressure with volume... But thats an example of a one of a kind, godzillawoofer. 20,000 watts, and possibly over 400 db- the thing is totally unblowable, and it also has @ a $20,000 price tag. The matched 20,000 watt amp was $30,000- but it did come with a second, identical free amp. Guess somebodys gotta repay their r&d budget...

The speaker, physically, needs a frame that wont flex, sufficient room for excursion ( so the former { tube that the voice coil is wired around} doesnt recoil from a hard kick, and bottom out- causing the former to bend and make a scratching sound when the speaker basses) a bent former is one kind of blown, caused by too much volume/displacement. The db point for this widely varies between speaker models and designs.

If the former has sufficient room for displacement, and gets that huge bass hit that made the other speaker bottom out, it could do the opposite and tear the spider ( flexible, round fabric that holds the former and its voice coil dead center of the speaker magnet), and, if it tears thru the spider, it will likely tear thru the center of the speaker cone, maybe even right thru the dust cover, and poke out thru the cone of the speaker. If the former ( which holds the voice coil) is ejected from its home within the speaker magnet, the audio signal running thru the voice coil will produce no sound. If the coil isnt centered in the magnet, the speaker will not vibrate or create sound.

The former, voice coil, audio current and speaker magnet all work together to make an electromagnet which can vibrate an attached diaphragm and turn electrical current into audio. With a cheap sub, you can also tear the surround if you exceed displacement. If the speaker is physically solid, but you grossly overpower, or feed distorted audio to it, the voice coil can melt. Current creates heat dependent on its medium, but 1% distortion can blow a speaker at a 1/4 of its rated power.

I had a fosgate series 1 200 watt 15" former push right thru the dustcap on me, when i put it on a punch 60 with 600 watts peak power. It was rated 0.03% thd at peak. Distortion didnt kill it, nor did current. It was simply unable to physically move that far in and out without tearing itself apart. That would have been around 125 dB, but that was a series 1 on a punch series amp. It was just a subpar driver. But for 20,000, you can buy a sub that will blow your intestines far before you ever blow that subwoofer.