some questions from a noob in the stereo department.

[SUPERSUB87]

I have this sub box i found in our garage. im not sure how you measure the sub. is outer edge the true diameter or do you measure closer in towards the speaker. the outer edge is 12" so is it a 12? also if someone could school me on the differences in amps. (mono, dual, multichannel) that would be great. i want to set off some car alarms!

 

[tuffdogstudio]

More info about the sub box would be helpful. What type/brand/model/number of speakers is/are in the box. Are there ports (vent holes) in the box? Subs are prolly 12" if you measured outside outside edge across.

 

[SUPERSUB87]

More info about the sub box would be helpful. What type/brand/model/number of speakers is/are in the box. Are there ports (vent holes) in the box? Subs are prolly 12" if you measured outside outside edge across.

i think the box was custom made. its just a long slim sub box. about 34" long. 16" tall. and 7" thick. It housed a 12" jl audio sub with a 5 3/4 bottom depth. what i really need to know more about is the amps. I'm going to buy a new 12" (most likely rockford fosgate p2's, unless someone has had a bad expierence with them.) and i was wondering about the distribution of watts from an amp to subs. i also was looking into two 8" subs as well and was hoping to be able to connect the three to the same amp.

 

[m1ndless]

For one sub, go with a Mono Amp, they are pretty much made for subs, get one that has at least 250/watts RMS, shouldnt run you more than 250-300 for a nice amp.

You can actually get a really decent Lighting Audio Amp at walmart, and it is only like $60, pushes my 10" MTX Thunder 5500 no problem.

 

[Hazy]

lol, mtx is good because it requires no watts at all and still sounds awesome. but underwatt a jl and goodbye!

 

[chevyin]

i think the box was custom made. its just a long slim sub box. about 34" long. 16" tall. and 7" thick. It housed a 12" jl audio sub with a 5 3/4 bottom depth. what i really need to know more about is the amps. I'm going to buy a new 12" (most likely rockford fosgate p2's, unless someone has had a bad expierence with them.) and i was wondering about the distribution of watts from an amp to subs. i also was looking into two 8" subs as well and was hoping to be able to connect the three to the same amp.

Not exactly sure what you are wanting to know about amplifiers. Its a wide topic, so I'll try posting a good link that go over the basics.

Amplifier classes: http://www.bcae1.com/ampclass.htm

The home page for this site is http://www.bcae1.com/ The Index is on the right, it will go over everything you should need to know to properly match a new sub and amp. If you have any questions, ask away.

lol, mtx is good because it requires no watts at all and still sounds awesome. but underwatt a jl and goodbye!

What does that mean?

Underwatt? That's a new one on me. If you mean what I suspect you do, then I should tell you that you simply cannot 'blow' a speaker by underpowering it. Never, under any circumstances. Period. No speaker... let alone any one particular brand (JL).

MTX is known for alot of things, highly regarded SQ isn't one of them. But to each their own.

 

[Hazy]

underwatting is the worst thing you can do... if you don't no that then i don't no what to tell you. i install audio crap all day.

 

[chevyin]

underwatting is the worst thing you can do... if you don't no that then i don't no what to tell you. i install audio crap all day.

Go ahead, try and tell me how underpowering a speaker, any speaker, will blow it. I dare you to even try and explain. Go ahead, Im waiting...

A speaker can be blown 2 ways, thermally (overheat it) or mechanically (push the cone/suspension too far) Neither of those situations are caused by too little power.

Let me ask you this, if less power blows speakers, why dont they blow when you turn the volume down?

You've fallen for one of the biggest fallacies in car audio these days, that underpowering kills speakers. Its not your fault, you simply regurgitate what your friends tell you, but its completely bunk.

Let me put it this way, my sig in several car audio message boards: "No speaker, in the history of speakers, has ever been blown by too little power. Ever. I don't care what your friend told you, he's a dirty liar."

Now, you say that's not true. Go ahead, prove it. But I warn you, Ive had this 'debate' at least a hundred times before (you are regurgitating a very popular fallacy) and I do not lose these debates, simply because I am correct.

If you install as much audio crap as you let on, Id think you wouldn't need this explained to you. Honestly, alot of people believe the myth you are spreading here, but only those people who have no clue how speakers truely work, or are destroyed. Not busting your balls, but study up abit more before spreading info on the net. You are spreading false information. And when busted, acting like a 'pro' doesn't make you look any less incorrect fyi.

 

[Hazy]

wow, thanks for proving me right. i no that sounds weird but you said "mechanically (push the cone/suspension too far)" and that could very well be the user playing to loud and not enough clean power and clipping occurs. don't just have a one sided opinion, there are many ways to blow a speaker. hell a speaker can blow an amp. do a simple search for yourself, they will tell you that "there is alot of debate on this topic". so don't just shoot an idea down. why not over power it a little and have some head room. im done with subject.

 

[chevyin]

wow, thanks for proving me right. i no that sounds weird but you said "mechanically (push the cone/suspension too far)" and that could very well be the user playing to loud and not enough clean power and clipping occurs. don't just have a one sided opinion, there are many ways to blow a speaker. hell a speaker can blow an amp. do a simple search for yourself, they will tell you that "there is alot of debate on this topic". so don't just shoot an idea down. why not over power it a little and have some head room. im done with subject.

No, there is no debate over this subject, not by anyone knowledgeable.

You forget I told you, Ive had this debate 100x before... think I have never come across the clipping arguement? What happens when you 'clip' an amplifier? Besides squaring off the waveform in the signal, output from the amplifier goes through the roof. So, now that 'underpowered' amplifier is being clipped well beyond its rated output, and no longer 'underpowering' the speaker. So again Im sorry, but you simply do not understand the subtlties of this 'debate', you cannot blow a speaker by too little power. Ever.

BTW, usually when someone clips an amp and 'blows' their sub, its thermally, not mechanically. Not always, depends on the situation (box, vented vs sealed, tuning, SSF, etc) but usually.

And its true, there are only two basic ways to 'blow' a subwoofer, as I described above. If you dont believe me, feel free to look it up, plenty of info on the net about it. If you have trouble finding it, let me know, I can provide links.

A sub can blow an amp? What does that have to do with this discussion?

I never argued against headroom, Im simply telling you the statement "underwatt a jl and goodbye!" is absurd, for many reasons. If you wish to continue this, Id be glad to continue pointing out why. Otherwise, bowing out of the discussion might be best, until you do some more research.

 

[5280k5]

Sorry for the hijack (might be a good thing though), Chevyin what car audio forum you usually hang around on?

I've been spending some time lately trying to "learn" about a lot of this stuff, and yeah most is over my head but I want have some idea what I'm doing before I just start throwing crap in a car.

Caraudio.com seems to have some pretty good info, Termpro is pretty good too but beyond my level....

 

[chevyin]

Sorry for the hijack (might be a good thing though), Chevyin what car audio forum you usually hang around on?

I've been spending some time lately trying to "learn" about a lot of this stuff, and yeah most is over my head but I want have some idea what I'm doing before I just start throwing crap in a car.

Caraudio.com seems to have some pretty good info, Termpro is pretty good too but beyond my level....

caraudio.com - okay, abit immature, bad moderator

caraudioforum.com - largest car audio board on the net last I heard (for population)

elitecaraudio.com - excellent for soundquality setups. Alot of national "SQ" competitors hang out there, can get advanced

http://www.diymobileaudio.com/forum/ - excellent forum, more high-end stuff

I have several other smaller ones, and prolly a cpl larger ones Im forgetting, but that's my main list lately.

 

[Hazy]

okay, well lets start with why underwatting a speaker can damage or even blow it. when you underwatt a speaker the speaker has to work harder to produce the same amount of sound as if it were getting the proper wattage. so because of this extra work this creates heat,and also more thd ,so youre saying that with more heat in the voice coil and higher thd's this would not damage or even blow a speaker . sorry to say but youre an idiot. topic done.

 

[chevyin]

okay, well lets start with why underwatting a speaker can damage or even blow it. when you underwatt a speaker the speaker has to work harder to produce the same amount of sound as if it were getting the proper wattage. so because of this extra work this creates heat,and also more thd ,so youre saying that with more heat in the voice coil and higher thd's this would not damage or even blow a speaker . sorry to say but youre an idiot. topic done.

Okay, Im growing impatient with you. Ive tried to be civil, but you do not have a clue how a speaker works. Let me explain to you, maybe you will listen.

Your example defies the laws of physics. The speaker will not 'work harder' to produce the same output with less input wattage, that is impossible. The speaker's voice coil accepts input wattage from the amp, and moves an amount based on 1) the amount of wattage, and 2) the efficiency of the speaker/enclosure combination.

Heat is not a byproduct of the work created (cone excursion, sound produced), its a byproduct of current passing through the coil, period.

THD is a byproduct of a loss of BL. I bet you dont even know what BL is (google it Mr Professional). As the coil leaves the gap, BL (motor force) is lost, and linearity goes down. If you dont believe me, fine, look up how xmax is defined... when BL drops below 70%. So please, spare me your school-yard ideas on what THD is, how its created, or how you avoid it. THD is NOT a byproduct of your misguided idea of 'work' created.

This topic will only be /done when you decide to stop spreading unbelievable stupidity within it. The sooner you realize this, the sooner it will be over. You know jack about how speakers work. I should be charging you for this little lesson.

Have a nice day.

 

[chevyin]

Look dude, just know that Ive been around car audio a while, longer than most these days, and I generally dont speak unless I know what Im talking about. This is the case here. Take it as a learning experience. I dont want to start a fued here, but I do want to make sure the proper advice is given on this board (sort of taken it under my wing I guess).

If you have any questions on the info Ive posted, feel free to ask me here, or via pm if you'd prefer.

 

[Hazy]

Okay, Im growing impatient with you. Ive tried to be civil, but you do not have a clue how a speaker works. Let me explain to you, maybe you will listen.

Your example defies the laws of physics. The speaker will not 'work harder' to produce the same output with less input wattage, that is impossible. The speaker's voice coil accepts input wattage from the amp, and moves an amount based on 1) the amount of wattage, and 2) the efficiency of the speaker/enclosure combination.

Heat is not a byproduct of the work created (cone excursion, sound produced), its a byproduct of current passing through the coil, period.

THD is a byproduct of a loss of BL. I bet you dont even know what BL is (google it Mr Professional). As the coil leaves the gap, BL (motor force) is lost, and linearity goes down. If you dont believe me, fine, look up how xmax is defined... when BL drops below 70%. So please, spare me your school-yard ideas on what THD is, how its created, or how you avoid it. THD is NOT a byproduct of your misguided idea of 'work' created.

This topic will only be /done when you decide to stop spreading unbelievable stupidity within it. The sooner you realize this, the sooner it will be over. You know jack about how speakers work. I should be charging you for this little lesson.

Have a nice day.

you didn't prove anything.

simple - anything that has resistance is going to create heat, hints the voice coil. the voice coil of a speaker moves "up"and"down" with the cone.the voice coil is around the pole piece wich is vented by the way. i wonder why that is ,could it be to dissapte the heat that is created. but according to your theory heat does not exist how is that possible. this is a simple answer to the textbook report you misenterpreted, copied and pasted out of an mecp book to make evryone think you know everything about everything. so if your expecting a giant report on the way things work you arent going to get that here. all im giving is real answers explained in a way that evryone can understand. late

 

[chevyin]

you didn't prove anything.

simple - anything that has resistance is going to create heat, hints the voice coil. the voice coil of a speaker moves "up"and"down" with the cone.the voice coil is around the pole piece wich is vented by the way. i wonder why that is ,could it be to dissapte the heat that is created. but according to your theory heat does not exist how is that possible. this is a simple answer to the textbook report you misenterpreted, copied and pasted out of an mecp book to make evryone think you know everything about everything. so if your expecting a giant report on the way things work you arent going to get that here. all im giving is real answers explained in a way that evryone can understand. late

reading > you

I never said heat was not present in the coil, I said it was due to something other than what you aparently think it is.

The heat IS created in the coil, you simply dont understand why. For example, a clipped signal wave will stop the cone's motion for a portion of every cycle, due to the flat in every waveform. The cone stops moving, yet current still passes through the coil. If your theory were true, heat would cease to be created, yet its not. This is yet another reason why clipped signals are bad... more heat generated due to excess wattage, less cone motion to help dissipate this heat.

Why do you think heat is created in the coil? You simply fall back on your 'back and forth' motion theory, yet the coil does not rub against the former, so where is this heat created? Hmmm?

Yes, anything that moves forms heat. But I assure you, the miniscule amount of heat formed on the spider(s) and surround as they flex are a drop in the bucket compared to all that current passing through the voice coil. The fact that you think this is the only way heat is formed while a speaker works... is astounding... for a 'professional'.

Do you even know what forms the 'resistance' (ohms) of a particular speaker? Do tell, oh knowledgeable one. I know you dont, otherwise you'd see the gaping flaws in your little theory. Maybe you can google it.

I dont have to prove you dont even grasp simple highschool physics, every one of your replies does it for me. You still haven't explained how you think the woofer will magically 'do more work' to make up for the lack of wattage. Your BS just keeps piling up higher and higher.

None of my replies are copied/pasted out of anything, let alone that elementary MECP certification book. Feeble attempt to discredit me, rather than my points. You failed. But thanks, I sound like Im pasting from experts. Nice burn.

But seriously, its installers like you that make me glad I know what Im doing myself. God knows how many unknowledgeable customers you've misinformed. Learn before you spout off, 'professionals' like you give the car audio hobby a bad name.

You are in way over your head, I suggest you stop making yourself look worse. I really dont want to fight, but I wont back down from your BS.

 

[Hazy]

well aparently we are always going to disagree on this situation. the fact is that there are installers who beleive that underpowering is bad and some that dont. even through this entire conversation you still have not stated how its not bad to underpower a speaker. we both have made strong points on this and i think that instead of acting like little kids about it, we should just leave it be. we both have good and bad points about the subject and always will, and we wont be the only ones to have this discussion. so it was fun. late

 

[chevyin]

well aparently we are always going to disagree on this situation. the fact is that there are installers who beleive that underpowering is bad and some that dont. even through this entire conversation you still have not stated how its not bad to underpower a speaker. we both have made strong points on this and i think that instead of acting like little kids about it, we should just leave it be. we both have good and bad points about the subject and always will, and we wont be the only ones to have this discussion. so it was fun. late

I still have not stated how its not bad to underpower a speaker? You do it every time you turn down your volume knob. If that's not enough proof for you, then you are sincerely hopeless.

Im sorry, not trying to be an ass, but Ive yet to see you make one valid point that shows putting LESS power to a speaker than its rated MAXIMUM will hurt it, in any way. And you never will, because its impossible.

Feel free to bow out of the discussion if you want. But if you think you held your own on this debate, you are only fooling yourself. There is absolutely no way less power equals blown sub.

Laters.

 

[BadassBlaze]

interesting debate. I have always heard that underpowering a speaker would blow it, and i thought it was weird. Now I dont know exactly how everything works in a speaker, but i know enough combined with me taking physics in college right now to be able to say that chevyin is right about the heat being produced. There is no way that the large amounts of heat that are created in a speaker come from the movement of the cone and related parts. There isnt anything with enough friction to create that amount of heat. But, if you have signal/power (excuse my terms hadnt had electrical physics stuff yet), that will create alot of heat...why do hairdryers, heaters, anything that provides warmth pass power thru a wire? Resistance in the wire creates heat, and that is what is being dispersed by the vented pole piece, not the miniscule heat produced by the movement of the cone. Watt=joule/second, so while headroom is good, i think it would be bad to over power a speaker, that is, sending more energy thru it than it was meant to handle. More energy=more heat=bye bye speaker