Shogun

I gather that your shop is a dealer for MTX? If it was me, I would recommend trying out a few different subs to see what sounds best to him.

Now, as far as your idea that underpowering a sub is a big factor in blowing them, I hope that you believe that people with low power amps turn the gain up to maximum and into clipping. As long as you do not crank the gain up, you will send a clean and unclipped signal.

Think about this, do your parents listen to the radio full blast all the time? Or do they listen to low - medium volume for years? Volume controls how many watts are being sent to the speakers (or subwoofer) at low volume, the headunit will only put out, say, 5 watts to speakers that handle 30 watts. Same thing with evenly matched sub and amp when your not listening to it full blast. You can not kill a speaker with a lower powered and properly set amp.

There are only two ways to blow a subwoofer in a car: overpowering them or sending them a clipped signal.

tc-guy

i have heard of underpowered amps causing speakers to blow but have not seen it firsthand before. i think what he said up there is right. if ur amp is not that powerful maybe its sending out bad clipped signals to ur woofers causing them to blow.

Shogun

Audiobahn is not as bad as people make them out to be. I had a 15" 500 watt RMS entry level Audiobahn matched with a Crunch Blackmaxx 500 watt RMS amp. Everything properly set and in my own built box (not bad for a first try) and it lasted for 2 years with great sound and still works. I do not have it in my tC because I want a molded box for the corner of the hatch.

And just so you know how much I was into bass (and still am but more towards sound quality, SQ), I bought or downloaded just about any rap song that had a lot of bass, even if the song was crap. AND, I have Bass Mekanik CDs to listen to the lowest and loudest bass possible.

cme42ns

Most subs are blown becasue of not enough power.

When an amplifier is operating normally, its out put is AC voltage. However, when an amplifier is pushed outside of this range (clipped) it puts out DC voltage.

The best example is your cars cigarette lighter. It consists of a copper coil that gets red hot when DC voltage is applied. The same thing happens to your speakers, since their voice coil(s) are usually copper. Thus the burning smell. If the coil gets hot enough it will either break (no output from sub), melt the glue an unravel (scratchy sound) or weld itself into the gap (frozen speaker).

This generally does not occur with AC voltage, so having an amplifier that has more power than you need is the best choice.

Of course, you need to be aware of the mechanical and power limitations of the woofer as well. But, I have run 1000 watt amps on 400 watt speakers for years. Keeep in mind that the amplifier should very rarely, if ever, be pushed to that maximum output. Once you cross that threshold, the amp is clipping. Also, since music is dynamic (unless you play test tones for long periods), the peak power is not sustained for an extended period and most woofers will handle that no problem.

When comparing amp power ratings, it is best to use the numbers that reflect a CEA2006 guideline.

Shogun

Actually, most subs are blown due to clipping. People think that as long as the bass gets louder, it is okay. You cannot underpower a speaker to death if it is set right.

I quote this again because of your own system. You run 4 15" 500 watt RMS subs powered by two amps that can only do 2 x 150 watts RMS @ 1 ohm (or 1 x 300 watts). This means you have 2000watts of speaker with only 600watts of power. Or, four 500watt speakers only getting 150 watts of power each.

You can run an under rated amp perfectly fine with no downsides AS LONG as the gain is not set to cause the amp to go into clipping. Speakers do not care how much power they get and amps do not care about how much power speakers can take.

A 200 watt amp will power a 1000 watt subwoofer fine and will not blow the sub if set properly.

The only way to blow a sub is by overpowering it or sending a clipped signal to it.
When set properly, no amp will send a clipped signal regardless of subwoofer used.

Shogun

Where did this come from? AC voltage? REALLY? There is just barely a change from DC to AC and back to DC. Speakers run on DC power.

"As stated before, all power amplifiers have a DC power supply which provides power to (among other things) the output stage of the amplifier. For most amplifiers, the power supply consists of a "plus" supply and a "minus" supply. The two voltages are often referred to as "rail voltages" or simply "rails". As an example, a 200 wpc amplifier (at 8 ohms) might have a power supply voltage (rails) of +/- 60 volts DC. This means that the output voltage which drives the speaker can never exceed + 60 or - 60 volts. If the amplifier is playing at near full volume, and someone “cranks up the volume”, the amplifier will attempt to put out more power. However, the power required to meet the sudden new demand for more volume cannot be met by the power supply voltage, which has limits of +/-60 volts in this example. The result is a waveform with the top portion (or peak) "clipped" off (hence the term "clipping"). Such clipping represents a distortion which is added to the waveform (and if it is severe enough it will be clearly audible). If a signal is severely clipped, the waveform takes on the shape of a "square wave", and the resulting sound will be absolutely hideous. Clipping can be easily observed using an oscilloscope attached to the amplifier output."

"Clipping is not usually a major problem for amplifiers (unless it is extreme), but it can be very detrimental to speaker systems. Whenever clipping occurs, two things happen: (1) the spectral content of the music signal is altered (high frequency components are generated), and (2) signal compression occurs. If excessive clipping occurs, tweeters will be the first to blow followed by midrange drivers. Woofers are best equipped to survive clipping (unless the abuse is blatant)."

Maximum output is not a problem. Trying to go PAST maximum output is when clipping will occur. The term, maximum output, means the most amount of power an amp can produce. As stated above, trying to go PAST that maximum amount of power does not produce more power, it clips instead.

cme42ns

So if you look at a sine wave of undistorted amplifier output (voltage), what do you call the positive and negative peaks? Alternating current (AC).

When you plug a subwoofer into a wall socket (not recommended, but we do it all the time for demonstration) you will get a 60hz frequency.......A/C!

If you hook that same subwoofer to a car battery, you will get a fried voice coil just as in the cigarette lighter example.

Granted, the woofer needs to have the mechanical engineering to withstand 110v-120v AC, but there are manufacturers building woofers to handle such scenarios.

Shogun

"Power Supply: The purpose of the supply is to convert the auto's battery voltage to a higher voltage. For example, if an amplifier is to produce 100 watts into a 4 ohm speaker, we need 20 volts RMS. This implies that we need about +/-28 volts. (20 volts R.M.S. = 28.28 volts peak). We call that the "rail" voltage. Since the amplifier's output transistors cannot pull all the way up to this rail, we actually need a slightly higher voltage.

The process is to convert the 12 volts DC into AC, feed it to a transformer and convert it back to DC again."

This is from http://www.wickedcases.com/caraudio/amplifiers.html

You do realize that a square wave still has alternating peaks right? The peaks are just clipped. So, even if alternating peaks meant AC, AC is what kills the woofer still, but this is not the case.

And speakers work when being plugged into a wall socket because it alternates at a constant rate like you said BUT, it always alternates at that frequency; you can't control it.

cme42ns

"Amplifier output is typically measured in watts per channel, with a normal stereo system having two channels, left and right. You'll frequently see "RMS" after the wattage figure — this stands for "Root Mean Square," which is a mathematical measurement of the magnitude of the AC signal. More watts means more power output to the speakers, which in turn means louder volume. " - Edmunds.com

"Exceeding a loudspeaker's power limits by a large factor almost always causes permanent damage. The tweeters are usually the first to go under circumstances of abuse, since they have the lightest voice coil made of thin wire which easily deforms, or even melts, if the temperature rises excessively. Tweeters are usually designed (and rated) keeping in mind that a typical music signal doesn't contain much power (or energy) at the higher end of the audio spectrum. Thus a tweeter rated for 50 W is meant to be used with a 50 W amplifier only if the signals below the tweeter's lower operating frequency are filtered out, and generally only if the material to be reproduced is 'musical' (with little power in the high frequencies). Thus, feeding a low frequency (or a DC) signal to a tweeter, even though it may be electrically within the tweeter's specification may cause permanent damage. A badly clipping amplifier may also damage the tweeter despite a crossover, since a clipped waveform generates high-frequency harmonics which can contain sufficient power to damage a tweeter (ie, a non-musical signal).

Most woofers (and mid-ranges) can easily take up to 1.5 times or more power than their power rating states. However, this is dependent on the particular driver and on the duration of the overload. Another factor to consider is whether or not the amplifer driving the speaker was being pushed to the point of harmful clipping, because a clipped waveform can cause damage. Woofers can usually absorb a lot of power before burning out or suffering damage to their moving systems.

Physical damage occurs if the signal causes the woofer's cone displacement to exceed the safe Xmech limits for prolonged periods. In rare cases, a very loud signal may cause the coupling between the parts of the woofer to simply give way. Even small amounts of DC energy fed to the woofer may cause twisting or deformation of the voice coil such that it rubs against the pole-pieces or magnet. This typically happens when an amplifier produces DC current at its outputs - a condition typical of a failing (or failed) amplifier. In addition, turn-on transients can contain enough energy to cause driver failures; there are several schemes which delay connecting the speaker outputs for a few seconds after the amplifier is powered on. Too much power, generally over time, can cause the voice coil to fail (deformation, melting, insulation failure, ...). In all cases, replacement or full repair of the driver are the only options." - Wikipedia - Loudspeakers - Care of

Shogun

DC is NOT a clipped signal, in your own stuff.

You know, I think it is about time for us to find somewhere to agree since both our sources like to say different things.

You CAN blow a speaker with too much power.

You CAN blow a speaker with a clipped signal from any amp.

You can NOT blow a speaker just from using a lower wattage amp than the subwoofer can handle. A pint of milk can still fit in a gallon bowl. No one has yet to tell me how your parents and even you do not blow speakers when listening at a low to medium volume, thusly, putting out less wattage than the speaker can handle. Especially when people just replace speakers and not headunits.

ZTC

ive heard from my jrotc instructor who seems pretty qualified in speakers and music
(he's starting a business on it and runs like 3 15's in his monte carlo)
but he says you cant blow a speaker with just power its the frequencies you make it hit. he explained that with a lil story with a pack of beer a 7 inch steal something bose speaker and a 5000w amp

Zsanz

go snag a w7 man im sure that they will be able to handel your amp


while speaking of subs is anyone interested in a alpine type R and a 500w rocford???

Zsanz

and true about killing a sub with the frequencies but if u do have a lower powered amp to a higher grade sub playing all kinds of frequincies you should be fine however if u match the peak rms on a sub to the continus rms on an amp you might have a problem at common frequencies if played at high volumes

yostc

i looked but didn't see if anyone had said it yet...if you have blown that many their very well may be wired wrong. if you were trying to wire 4ohm subs out of series and ran them at 8 ohms that would defenetly do the trick would it not?

JohnathonSull

Thanks for all the info! I actually had circut city, frys electronics and bestbuy install them. it shouldnt have been wired wrong i would think.

ZTC

ill be intrested in june lol

Zsanz

haha wow i plan on buying my tc in june hence that type Rs gotta go..keep in touch lol

cliffud

2 items should go on the shopping list man...

1) JL Audio 13w7
2) JL Audio 1000.1



Loving my setup.

NoLimitzBuilt

DC is a clipped signal. Music is a AC signal. It is Alternating Current.

Shogun you are right to a point. You can blow a speaker by under powering it. When people under power a speaker they usually turn the gain on a amp up to try and make up for the lack of power. As for using your parents as a comparison doesnt make any sense. They are not using amps with gains. They are using a headunit that has a set adjustement and designed to work with the factory speakers. And yes you can blow factory speakers with a factory headunit.
The person behind the volume **** must know the limits of system and how to determine the limits. I have taken a 300 watt speaker and ran 900 watts to it and beat the crap out of it. Never blew a speaker but I knew the limits that the system could handle.
The gain on a amp is not a volume ****. It is there to level match the amp with the headunit. It is designed to make a low end headunit or a highend headunit and give you the same output out of the amp. For example. A headunti that has a preout voltage (rca voltage) of say 250 millivolts will have to run the gain on a amp higher to make the rated output. A headunit with say 4 volts will have to run the gain on the amp alot lower to make the same power. It is designed to be a versatile amp.
As for the issue here on his speakers. It sounds to me like he is running it to hard for what it can handle. The power of the amp and speakers sound pretty close if I remember right. It sounds like he does not the limits of the system. The other thing that noone has mentioned here, is if the enclosure he is using is correct. There is specs for each and every woofer out there. Some speakers will not work in certain enclosures. I not once remember anyone asking what box they are in? I know they are in a ported enclosure. But if the box is to big for what the woofer needs you will loose power handling of the woofer. So there is alot of factors that come into play here.
I hope you get everything fixed and back up and running no matter what brand you go with. Hopefully who ever sets it up and installs it for you does it correctly so you do not continue to have issues.

JohnathonSull

Thanks for the explanation. You are right on the power leves being close. the subs 1200watt max, 800rms and the amp is 1500 max, 900rms. The subs came in a ported enclosure designed for them by polk. its a package deal from polk the encludes the two subs and the enclosure made just for them. You are probably right about me not knowing the limits. I would adjust the amp volume along with the bass on the HU all the time because it wouldnt be loud enough for me. The next setup will haft to be powerfull since i now know not to mess with the gain much once its be set.