Buy an amp to overpower subs?

  O.K., I read in a Car Audio & Electronics that you should buy your amp at least a couple hundred watts bigger than what your subs are rated for so that the subs are being driven well within the amps "clean" capabilities. Does this sound right, and if so how would you set your levels so as not to fry the sub? For example, I have 2 SVC subs that handle 500W ea. I want to buy an amp that is rated at 1400W ( all RMS, of course.) Am I playing with fire here?

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

i have always overpowered my own systems and i've never blown up anything ever.... you can turn it up and still be using clean power...just use your ears as a benchmark...  distortion ( the amp clipping ) will fry a speaker far more quickly than an excess of clean power.....

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979

What does clipping mean?

DYohn wrote:

Clipping is distortion that occurs when an amplifier is being pushed beyond it's usable limits.  It is called clipping because on an oscilloscope you can see the waveform tops being "clipped" off and flattened out.  Trained ears can her it when it begins, and most anyone can hear it when it's severe.  Lower quality amplifiers (and especially head unit buiilt-in amplifiers) tend to go into clipping at the RMS output limit. Clipping can destroy a speaker, and in very severe cases can destroy an amp.

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

Is there a way to tell by ear if you are pushing too much power to the subs, even if it it is clean power? It shouldn't be clipping, but will there be any indication?

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

I am guessing that the opinion you read and referred to in your original post was from a participant in a forum, and not a highly qualified audio engineer.  I am just a forum participant too, and certainly no engineer of any kind, but I know that buying an amp that is one to two hundred watts more powerful than the speaker can handle is just plain foolish.  You better have some extra speakers on hand to replace the ones you ruin.

It seems like it is the common mistake of not understanding how to adjust the amp sensitivity (using the gain control) with the volume on the head unit.  An amp that will produce 1000 watts is going to make that much power no matter where the gain control is set.  Let's say you bought that advice and decided to overpower your speakers.  As you turn the volume up, you won't get to that 'critical stop' point where distortion begins and you know to back off because you're at the limit.  Too much power is fed to the speakers and they over-excurt.  Too much heat.  And some other things I don't know about.  Goodbye.

However, if the amp and speaker RMS are matched, and the amp input sensitivity is set to match the output of the head unit (see setting gain), as you turn the volume up you will reach that 'critical stop' point because the distortion will sound terrible and you'll turn it back down.  That is, if you are pushing it past the point on the dial you know not to go past.

This can be argued, and is, either way.  Because truth is both will destroy a speaker.  But one way makes sense and the other way doesn't.

To answer your Question " is there a way to tell by ear...", the answer is sometimes and sometimes not.  Maybe and maybe not.  Don't overpower your speakers so you don't have to find out for yourself.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

The guy that wrote the article was Steve Brown from Alpine USA. He designs and builds alpines show cars.

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

No you shouldnt overpower your subs. You should buy a good enough amp that will run its true RMS which should match the subs RMS

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dream it, build it, fiberglass it

I went to high school with a Steve Brown.  He was a real bullsh!!ter.  I'm going to search for his article.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

A little bit of a common name isnt it?

Some articles written by Steve Brown.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

yeah- it was in the competition corner articles

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

No doubt he knows what he's talking about, he's built some amazing comp systems.  Let me not be the one who says he's wrong.  But is there a philosophy among high level competitors about this?  Is it because they are so precise with every detail that they can go this overpower route?  And is it a sane approach for the regular street guy building his system?

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

stevdart wrote:

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Is it because they are so precise with every detail that they can go this overpower route?  And is it a sane approach for the regular street guy building his system?

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My question exactly! Those are the words I was looking for!

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

clipping is created when you set your gains incorrectly. if you have an amp rated for higher than the rms value of the sub and your gains are set properly or a little under then you should have no problem running your subs or have to worry about them burning up or getting a clipped signal
correct?

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Quad L Handyman services

Two things here.  Even with a properly set gain you can easily send the speakers into clipping.  How?  By turning the head unit volume up past the point where you should stop.  The signal to the amp becomes distorted and, of course, is amplified.  Second thing...you say if the amp is rated at higher output than the speakers can handle...but the gain is set correctly...then there is no fear of burning up or clipping?  Possibly true to the clipping part, but there is still the HU, and you know there is a point where it will distort.  But the burning up part?  How would you know?  Until you hear the voice coil banging or smell smoke?  Overpowering is a certain killer unless you know precisely where to stop turning that dial....and you would have to rely on meters because you wouldn't hear clipping to tell you to turn it down.  That's why I don't think this way of doing things is good for the average guy.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

While I agree that having amplifier head room is a good thing (this would be the theory behind using an amp well below it's power limits) I will argue that it is much safer to use loudspeakers designed to handle much more RMS power than the amplifier you use.  When I specify a professional sound system, I always specify loudspeakers rated 2 to 3 times higher than amplifier RMS power rating.  Then, set up the amplifier properly so it can never clip with max pre-amp input, and both the amp and the speaker are operating well inside their normal ranges, staying away from maximums and peak excursions, and all is well.  I usually drive professional loudspeakers designed for 500 watts RMS with no more than 250 watts of amplifier power.  If I need more acoustical output, design in more efficiency or choose higher power rated speakers.  The worst thing that can happen in pro audio (or in theatres, my real bread and butter) is to blow a speaker because the amplifier was too powerful.  That is called never work in the industry again.

Now in car audio, most people want their system to be as loud as possible, so they tend to match RMS ratings.  Then if everything is set up properly the amp and the speaker are both at their "hairy edge" of safe operation and will operate at their "best".  The danger of doing this is it doesn't take much to push the system off the edge and blow something, usually because of clipping.

The danger of overpowering a loudspeaker is driving the voice coil too hard and frying it, either with electrical power that is too much for the windings or by driving the speaker to its excursion limit, stopping VC movement and frying it with heat (the exact same sort of failure mode clipping causes.)  In my opinion, it is only safe to overpower a system if you know exactly what you are doing, have a very good pre-amp that yu can setup precisely, and NEVER drive the amplifier near the range of damage to a speaker.  This is the worst case condition for most every-day car audio users, unless buying new speakers every time the urge hits to "crank it" is acceptable to your pocketbook.

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Well said DYohn! I also agree that this overpowering aspect is best left to people who REALLY know what they are doing. If you cannot hear a speaker being overdriven, then do not take this route. (I never knew you were into theatre...) I have been doing it for years, like DYohn, and I can hear a driver being overdriven. I am a firm believer in dynamics, and I DO take the overpowering route, for this very reason. If you cannot keep you hand out of the volume control, you will ALWAYS be best off matching your amp power to driver rating.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

This is the way I have always treated this question. When I have a customer ask me I tell him to get an amp that has more power than what he needs and I will explain why. Lets say I set the gains on the system and the kid leaves. He looks at the system and decides that he wants his sub to be louder. He looks at the amp and see's that there is still room on the gain dial. So he turns it up. Now he is getting more bass but his amp that only puts out 230 watts rms is clipping his 400 watt rms sub like crazy because he cranked the gain. He either doesnt know what that sounds like or can hear the sub clipping cause its in his trunk. He blows the damn thing up and comes back pissed cause his sub blew up, claiming the sub is a piece of crap and that it shouldnt have blown up because the amp was barely putting half of the subs max power to it. I try to explain to the customer about clipping and he looks at me like I am a sleazy ass just trying to cover my tracks for a faulty product. Now if the same customer buys a sub that handles 400 watts rms and an amp that does about 500 watts rms and I set it up. The customer is far less likely to want more from the system because the sub is already being driven to full potential. It is also easier to explain to that same customer why he shouldnt turn the gain up higher than it is because in his mind he knows that he has more power than what the sub could handle and doesnt wanna chance blowing it up. While we are own the topic of power, we all know that manufactures tend to rate the equipment differently so if you by a Eclipse sub and a rockford amp, just cause the eclipse sub says it handles 600 watts rms and the rockford amp says it handles 600 watts rms that doesnt mean its gonna match up so that is where experience kicks in. I know that a kicker xs100 is not a good match to a punch stage 1 because even thought the kicker amp is rated at 50 x 2 and the stage 1 says it handles 150 watts rms, I also know that that kicker amp is underrated big time and would tear that little stage 1 apart. I also know that a American Legacy that is rated at 200 watts rms x 2 isnt gonna sufficently power a mtx 8000 because even thoug the rms power would match up the same I know the American Leagacy is bullsh*t ratings and are only gonna do those numbers right before it melts down. Mabye you think My theory is wrong but I have always overpowered everthing I use and it comes down to the fact that amps can always be turned down but if you try to turn it up so its no longer matched up to the head unit you are gonna clip and are gonna have problems. Everyone I know around here who either competes or runs higher quality equipment always over power their stuff. Also the lower you can keep the amp the less its gonna have to work and the longer its gonna last. Heat creates distortion and distortion creates, to borrow a quote from forbidden, sss. Smelly Speaker Syndrom and no one wants that.

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

I think you guys are forgetting something, and that is the enclosure used.  I know people who run 3 kilowatts to one of our subs, and yet I have seen this sub break with only a 250 watt amp.  The enclosure makes a large difference in the power handling of the subwoofer.  The thermal rating is somewhat useless once it is installed in a system.  Especially when you add the fact that many companies aren't too honest about their power ratings.

Steven Kephart

Adire Audio

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I agree with Steven... I run 2700 watts to a single Eclipse SW9122, 12 inch, DVC from the Eclipse DA7122 Amp. I can do this because I broke the driver in FIRST, measured the Theil-Small Parameters, after the 48 hour break-in period, and then built the enclosure for optimum alignment. I think I went for a Qts around .9, because it offers me the best combination of frequency extension and power handling. Granted, a Qts that high will usually give a bump in the response, but in this case the bump is at (I think I remember correctly) 87Hz, +3dB or so. I was not worried about this because I knew my crossover into the sub was going to be 50Hz @ 48dB, so there is NOTHING even close to 87Hz getting there for the driver to reproduce. I was also EXTREMELY meticulous in the construction and bracing of my box... It was cut on my buddy's router table, which he uses in his sign shop. I didn't even have to use screws. And before I get grief about NOT using screws, it does not need them, I assure you. I used gorilla glue, with weights and clamps to hold each and every joint until it was completely set. The assembly of the box took 8 days!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

 So those of you who do overpower your systems- I know my headunit's limits now. I know what to never turn it past on any adjustment. So if I do go the overpower route, how should I set my levels? Set the gain & crossover levels, put my sub level to 0, bass to 0, and slowly go up from there untill it doesn't sound right (I do have a pretty sensitive ear), and then back down a click or two and just never go past it again?

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

It is a very complex equation with no simple answer, which is why I always err on the side of caution and suggest under or equal power for speaker-amp pairings.  The proper enclosure can provide sufficient damping to increase a loudspeaker's power handling capability... and the wrong enclosure can severely limit it as well.  I have also run drivers rated at 35 watts with 300 watt amplifiers, but only with highly dampened enclosures and using carefully selected bandpass filters, and after the driver was properly broken in and tested.

Bottom line: in car audio on a forum like this, always recomend a SAFE configuration first, and always defer to the manufacturer's recomendations. 

Someone who is a competition professional or who really knows what they are doing and understands acoustic and electircal theory can of course build a system using 5Kw amps and 500 watt speakers, but if they know how to do this they probably won't ask how on this forum!  :) 

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