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What amp to get

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Silver - Posts: 785
Silver spacespace
Joined: November 21, 2005
Location: United States
Posted: October 11, 2006 at 12:47 AM / IP Logged  
an IMPROPERLY tuned amp CAN damage a woofer through under-powering.
If you are not driving the amp PAST its limits, then there is no risk of damage.
Read threads about 'clipping' and 'square waves'
Silver - Posts: 1,123
Silver spacespace
Joined: October 10, 2006
Location: United States
Posted: October 11, 2006 at 2:36 AM / IP Logged  
I don't know if the previous post is directed at me but I will respond regardless. first off..what does an "improperly tuned" amp mean. An amp is supposed to amplify the input, not tune it. You set the gain and crossover but this has nothing to do with the issue of underpowering destroying woofers. About "driving the amp past it's limits" I guess that is assuming someone is going to install an amp/ sub and not crank it? I don't know what dimension you live in but here 99% of my amp/sub sales are kids looking to annoy everyone in a 10 mile radius with what I assume is some kind of music. alot of my customers blow woofers because they have bought the typical amp that says 6.25 gigiwatts on it but puts out a little more then deck power. As far as clipping and square waves I don't need to read any threads about that, I am an audio and electrical engineer and learned about that and how to use an o-scope the first week. Then I was teaching about that at an installation school for 6 years. But you proved my point, clipping is audible distortion which appears as a square wave on an o-scope. This clipping is caused by underpowering a speaker, like if you connected a 12''  600watt  sub to a  head unit power it would surely clip. The more severly you are under powering, the worse the clipping. But technical mumbo jumbo aside, I see first hand as an installer for over 15 years woofers blowing from under powering. When I install the proper amp I notice I am not seeing them every other day with blown subs. That my friend, is the reality of it. I wish all my customers listened at low volumes but thats like telling a hard core alcoholic to just sip your beer slow. Ain't gonna happen. Peace
Copper - Posts: 210
Copper spacespace
Joined: January 21, 2005
Location: United States
Posted: October 11, 2006 at 8:31 AM / IP Logged  

Master,  What you are describing is a user issue, not an equipment issue.  My dad has been powering an Infinity Reference 12 with a 50 watt Blaupunkt amp for about 8 months now with no damage.....why?  because he simply wants to round out the sound in his Jeep, not because he wants to intimidate people.  If he pushed the amp to clip the sub would be fried in an instant. 

Their is no way that underpowering a subwoofer destroys it, it is when the operator cranks the amp past its limits into clipping that damage occurs.

And if you have all those qualifications you mentioned, that is great.  But their are alot of people on here with equal if not better qualifications (myself NOT included) that I have learned alot from.  I am not saying you are wrong, I am just saying that maybe you need to go at this with a little bit more of an open mind.


There are 3 kinds of people in the world, those who can count and those who can't
Copper - Posts: 365
Copper spaceThis member has made a donation to Click here for more info.spacespace
Joined: April 25, 2005
Location: United States
Posted: October 11, 2006 at 10:38 AM / IP Logged  

It doesn't matter if clipping occurs. It is when you drive the speaker past its thermal limits. So long as you keep within the limits of the driver, you will not burn out the voicecoil not matter how bad you clip the signal or how badly you "underpower" it.

I agree with j_darling2007 regarding your attitude. If you are so convinced that you are the have stopped learning. On top of that, to disregard what has been previously posted and feel that you don't need to read what was said...that speaks for itself, and to the limitations of your current knowledge, and frankly, will cause people to stop listening to what you have to say regardless of whether or not it is valid or useful.

The Flakman
I feel strange. I have deja vu and amnesia at the same time.
John | Manteca, CA
Moderator - Posts: 10,739
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Joined: April 22, 2003
Location: Arizona, United States
Posted: October 11, 2006 at 10:43 AM / IP Logged  

Where's the "beating head against a wall" icon?

Please read the "too little power" sticky thread.

Gold - Posts: 2,600
Gold spaceThis member consistently provides reliable informationspace
Joined: May 01, 2006
Location: United States
Posted: October 11, 2006 at 3:39 PM / IP Logged I stated the ruling stays forever until the world ends that you cannot underpower a woofer...Basically any speaker.
Silver - Posts: 1,123
Silver spacespace
Joined: October 10, 2006
Location: United States
Posted: October 11, 2006 at 9:33 PM / IP Logged  
Wow, didn't know this was gonna start a war. I did not reply earlier since I had to get some sleep and then get up for another day of installing and fixing all the disasters that "know it alls" have installed improperly  (the old "my homeboy did it")and have to replace incompatable equipment. But all this aside I really am an open minded person and I learn alot everyday. I just get a little rattled when I know something for a fact from of years and years of real world experience. Perhaps not everything can be proved on paper, or with diagrams and schematics, charts, scopes and specs etc, but I put my money on experience every time and leave the laws of physics and engineering to simply help prove points and try to help others not to make common mistakes I see every day. Just trying to help others save time and money. But the issue with this particular post has gone a bit off the deep end so I will try to clarify some of my statements since I think there is a misunderstanding. The issue seems to be what the definition of underpowering is (like depends what "is" is with Clinton) I am not so pigheaded as to think it is impossible to play a 5000 watt sub with a clock radio and that means the sub will blow. This is not what I mean. Also I think some of you do not understand the difference between a "damaged" speaker and a cooked voice coil. I also think many of you are not taking into account distortion, which is the number one cause for the old "my sub stopped playing". I don't know where some of you are getting your knowlege from but even before I knew what an ohm was I was told by every top notch installer, engineer, speaker manufacturer, rep, you name it that underpowering causes more returns and exchanges of subs then overpowering. Of course as time went on I found this to be the case first hand. I don't care if you want to call it clipping or anything, distortion will cause excessive heat and in turn fry a voice coil. Use common sense and think about what causes distortion and its effect. Also I hope you all understand that this is not about me trying to seem better then anyone else or holier then thou, I do not think that way about myself but I do know I have alot of experience and have worked very hard to get my degree and certifcations. That should be worth something but I will never say that I can't be wrong and welcome anyone to prove me so. I would be the first to say "I messed up, I'm an idiot" and take it as a learning experience. If anyone has felt insulted from my posts please don't take it personal as this way of communicating is VERY impersonal. If we were discussing and debating in person it wouldn't come off as it does on forums. Thanks everyone and enjoy while sharing, teaching and learning as I do.
Silver - Posts: 1,123
Silver spacespace
Joined: October 10, 2006
Location: United States
Posted: October 11, 2006 at 11:08 PM / IP Logged  
Also to nouseforname. I do not want this to become an aurgument as I think we actually are in agreement, just having an issue with terminology. You state "clipping is distortion that occurs when an amp is overdriven" I agree with that 100%. where I think we differ is what overdriven means. If an amp has enough power and is a match to the subs power handling what would cause it to be overdriven? Common sense as well as an understanding of what clipping is tell me that the output is basically "saturated" or in laymens terms it can't properly drive the woofer. There would be no logical reason to overdrive an amp if it had enough power. Am I missing something here? And this distortion we are talking about is what is frying voice coils, as I see almost everyday at work and when fixing systems for friends, family and side business. Good quality amps produce higher power levels at lower distortion. Low quailty amps may produce high "peak" output but it is rated at high distortion levels which kills voice coils, I see no argument of that fact. In another scenereo lets assume a good quality amp but low power, lets say 100w RMS @ 2ohms. This amp should produce clean power to 100 watts @ 2ohms. but if some knucklehead SPL junkie is trying to power a 5000 watt JBL with it he will most likely run that amp into distortion or as you put it "overdriven". I don't know what anyone else thinks but I see a problem with that.  Add to this a ported box that may have a 3db higher output at Fs but the power handling is now even more reduced as you go below the tuned frequency, another recipe for disaster. As far as gain control setting there is always debate about that. from everything I know about gain control is that people think it is a volume control and others think if you turn it up the amp will be more powerful. neither is true. A 200 watt amp does not become a 400 watt amp if you crank the gain. The gain is designed to correct input impedance mismatch since there are no industry standards for this. In the days of yor, when I started installing (age 15) if you purchased lets say, an Alpine deck, you HAD to use an Alpine amp. They didn't even use RCA's they used din cords which were different for each brand. Most amps at that time didn't have gain controls. Didn't need them as the equipment was matched. As the business grew people wanted more choices so we had to either re-pin the din cables or sometimes the aftermarket would sell pre made ones..example "sony to pionner"  or "blaupunkt to alpine" etc. At times there was problems since there was no way to adjust the gain so on some decks you would not have enough volume and on others the inputs were overdriven, essentially driven into saturation, in a sense you had distortion before the audio even got to the amp. All this aside please understand I am also here to learn, not just teach but have a right to stand my ground if I feel I am being accurate. I hope we can see eye to eye on many topics as I can tell you are very experienced and would like us to learn from each other which I guess is the purpose of this whole site. Peace
Silver - Posts: 1,123
Silver spacespace
Joined: October 10, 2006
Location: United States
Posted: October 12, 2006 at 6:13 AM / IP Logged  

someone told me to divide my long replys into paragraphs so it will be easier to read.

I will try to remember to do that in the future as I am new here and LEARNING.

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