Is my amp big enough

By directorj17 ยท 32 replies
Feb 4, 2004
  1. I am getting a 15" solobaric L7 Kicker and i have a 301S Punch amp will it sound good?
  2. Steg

    Steg TS Rookie Posts: 269

    depends on how you define good. depends on the quality of the cables and the quality of the recording....
    but by most lay-mans standards it will sound pretty damn good

  3. erickdj

    erickdj TS Rookie Posts: 69

    I'd like to differ to what Steg said. I'm by no means a sound or electronics engineer, but having built and owned several car sound systems I can say that your amp is far from adequate for a 15" solobaric sub. That amp is barely enough for a cheap $40 10" or 12" sub. Your L7 is more like a high-end sub. If you only want it to "make noise" as in: Is the speaker going to produce any sound? Yes, the sub probably will move, but it will by no means represent what the sub is capable of. In fact, it's been argued that underpowering a speaker can do more damage than overpowering. That's for the simple reason that in order to get it loud with a weak amp you would be driving the amp into clipping(overload). You also risk frying the amp. I don't know what your budget is like, but I'd recomend you look into an amp that can provide twice the power of your current amp. I have a Fosgate Power 750s, which pushes a pair of Alpine Type R 12" without breaking a sweat. I used to power those same subs with a much weaker amp, they worked, but the performance gain with the 750s was exponential. Not only do they sound louder, but the sound is much clearer as well. Hope this helps, I'd recomend you visit one of the car audio newsgroups. You can find them on google.
  4. YingYang

    YingYang TS Rookie Posts: 19

    L7s are not exactly SQ subs by any means and usually they need enclosures in the 4-5cu ft range. If you absolutely must have your L7, build a 5cu ft ported enclosure and tune it to about 30Hz for a nice, smooth rolloff. Those L7s are more SPL subs and can take 1500w easily if you know what you are doing, but 300w shouldn't sound bad if you have the proper enclosure.

    If you actually want more, give me your budget, the amount of space you have for an enclosure, and if you want sound quality (SQ), to be loud (SPL), or a mixture of both (SQL).
  5. YingYang

    YingYang TS Rookie Posts: 19

    Cables matter almost nil in car audio because of the amount of road noise that masks most of the minute variations that are detectable in a home setting. A cheap pair of shielded RCA cables and a good ground for the amp will get rid of any audible noise which could only come in the form of alternator whine.

    Most of the distortion in car audio systems comes from the wrong enclosures, *****s who don't know how to set gains on amps, and improper installs. Car audio mantra: 10% equipment, 90% install.
  6. YingYang

    YingYang TS Rookie Posts: 19

    First off, underpowering will never ever kill a speaker. If that were the case then everytime you turned the volume down on your stereo, you would be damaging your sub because you would be decreasing the voltage to the amplifier.

    There are only two things that kills speakers, heat and overextending the mechanical limits of the speaker's suspension. The latter only happens in ported and bandpass enclosures that are improperly tuned for the power that is provided to the driver.

    Heat, on the other hand, can come from pushing too much power to a driver or by severly clipping an audio signal to the point where you are getting almost direct current instead of AC. There are numerous different threads on multiple car audio boards that get highly indepth on this phenomenon so I won't bore you here with it.

    I personally am an electrical engineering student at a university with a 2 year background in fundamental acoustical physics and will be taking advanced acoustical physics classes next fall. I also own a good dozen subs that range from cheap $45 MTX 4000s to $450 RE XXXs. I'm not bragging but saying that I do know what I am talking about and have a shelf of books, hundreds of pages of tech papers, and a myriad of saved threads on my computer to back up what I stated. :grinthumb
  7. Nic

    Nic TechSpot Paladin Posts: 1,549

    I just like to point out that erickdj's post was accurate when he said that a low powered amp, when driven into clipping, can damage speakers. That is true for high frequency units, such as tweeters, only. I assume YingYang took this as refering to the 15" Bass unit, which of course, won't be damaged. Just thought I'd stop a potential argument before it got started.

    I'd also like to point out that cables DO matter, but only if you have a particularly bad set, because then you will get thin and lifeless sound (sometimes the sound can even be harsh and tiring to listen to). Its not just noise that poor cables introduce. They can alter the frequency balence of the sound, and in some cases this will be noticeable.
  8. olefarte

    olefarte TechSpot Ambassador Posts: 1,345   +13

    Well said Nic. While I'm not an electrical engineer, his thoughts are my thoughts exactly and I can't add much to it. I do believe that an underpowered amp driven to clipping will cause a lot more damage to speakers, at least tweeters, than an over powered amp.

    As to cables, Nic said "They can alter the frequency balance of the sound, and in some cases this will be noticeable." Absolutely true.
  9. YingYang

    YingYang TS Rookie Posts: 19

    Completely true. I knew he was talking about a subwoofer so he was only talking about 100Hz and below if xovered right. With a subwoofer, clipping is also extremely difficult to notice unless sever because of the lack of sensitivity at the frequency levels produced. The threshhold for most of us in the low frequency band is 3% THD. The only funny thing about clipping is that say I am pushing my RE XXX with a fully clipped 500w sub on a full range of music in a properly tuned ported enclosure. That amp will only produce a maximum of 1000w because of the clipping but my sub has a thermal RMS rating of well over that. You can still burn the coils out but most of us don't play sine waves in our stereo's often.

    Wire is wire, especially when talking car audio. We sometimes use welding cable in place of expensive power cable and lamp wiring is almost the same as speaker wire. I would say a fair number of us also use Walmart wiring kits with no qualms.

    With properly shielded RCAs in a car environment, do a double blind test. You can run the RCAs right on top of the power wire and do everything else except break the insulation. Wire is only made to carry a signal from one end to the other; unless you are using oxidized cables that is creating a deterioration of the fed signal, the signal at the input will be the same as that of the output.
  10. Godataloss

    Godataloss TS Rookie Posts: 482

    Underpowering a sub (as in clipping) WILL kill it as per ying yang's own argument. The erratic movement of the speaker cone caused by a speaker distorting due to clipping causes heat which will kill an amp and a voice coil (as you pointed out) no matter the size of the speaker.
    As for cables and such- the low impedances and high wattages of some car set ups absolutely necessitate good interconnects. I'm not saying you need $15 a foot Vampire Wire for a kicker in yer trunk, but if you are throwing around a +thousand watts of juice, you better have more than 18awg radioshak lamp cord or your asking for a fire.
    But this all begs the question- Who the hell needs a thousand watt car stereo?
  11. Nic

    Nic TechSpot Paladin Posts: 1,549

    Not so. The crystaline structure (amoungst other things) introduces phase shifts to the different frequency components that make up a typical audio signal (also affects other signals such as video - in fact all signals are affected in some way).

    Each time an electron meets a grain boundary, or impurity, in the cable structure, a phase shift is introduced (it takes longer for the electron to cross the boundary). This I know from my electronics studies at university many moons ago.

    This typically results in a spread of the spectral components that make up the signal, and each path traced by each electron will result in a different amount of phase shifting. This is one reason why large grain, high purity, oxygen-free copper became popular for use in audio cables (less grain boundaries, and less impurities equals less spectral phase shifts). The measurement of these defects is difficult, but the difference can be very apparent when listening tests are carried out using high quality audio equipment. There are many other factors that also play a part, and it is entirely possible that the effects depend to some extent on the components (amp, cables, speakers, etc.) that are chosen.

    Quite a few sceptics assume that cables simply introduce resistance, and so do not affect the audio quality of a signal. The only way to satisfy yourself that this is not the case is by doing some research and ultimately do some listening tests yourself.

    Sometimes cheaper cables can sound better than expensive audiophile cables, when used in certain systems, but that is very rare. Whatever the case, bad cables can make any descent audio system sound like a cheap radio, so thats something to bear in mind if you are unhappy with the sound you get after you have installed your system.

    As to clipping, the reason this can damage high frequency drivers, such as tweeters, is because clipping introduces a very large amount of high frequency noise into the output signal. In some cases this can be much higher wattage than the rating of your tweeter, which typically has a power rating that is much lower than a Bass driver. This results in burning out the voice coil of the tweeter. Bass units will also burn out if their maximum wattage is exceeded, regardless of whether this is due to clipping or not.
  12. Godataloss

    Godataloss TS Rookie Posts: 482

    Nic- clipping kills bass drivers the same way as tweeters. When an amplifier clips or distorts, the amplifier puts out heaps more high fre quency energy.The very nature of distortion is that it adds high frequency harmonics. Add this to the fact that a severely distorting amp can have a continuous power output that approaches twice - yes, two times -the amp's power rating. Sub-woofers take a real hammering whether in discos, PA's cars, or home. Distortion is difficult to hear because the sub woofers are too mechanically slow to react to the high frequency distortion components coming from an overdriven amplifier. But the woofer is still absorbing all of the amplifier power causing excessive voice coil heat and burn out. Thus the little statement in speaker warranties about if there are burn marks on the voice coil your warranty doesn't hold.User error - too much distorted amp power.

    Which circles back the the Freudian original title of this thread-
    Is my amp big enough? My best reply would be ABSOLUTELY- if you know how to use it.
  13. Nic

    Nic TechSpot Paladin Posts: 1,549

    Godataloss: I wasn't disagreeing with you, just clarifying the issue. Remember than most woofers will have only low frequencies fed to them because of the crossover used to split the frequency bands into low and high frequency components. All the high frequencies will end up feeding the high frequency driver and will not get as far as the bass unit. But you are correct in that too much power will kill any driver unit regardless of frequency. Also, remember that guitar amplifiers are deliberately overdriven so that they clip and produce large amounts of distortion that is then fed to the speaker unit. I've yet to see one of those die from clipping.
  14. Godataloss

    Godataloss TS Rookie Posts: 482

    Speakers can typically handle an amplifier of 2 times or more their rated power if the power is undistorted. I thought you meant maximum wattage as being manufacturer spec. This is misleading in view of the original thread and again we at Techspot become guilty of gross over-intellectualization.

    The original question was- "Is my <ahem> amp big enough?" We must assume he means powerful enough. I'd assume 300 watts would be enough for any application in a car, but if he wants to be one of those people that drive by my house in the middle of the night and shake my window frames with bass notes that they cant even hear inside their car just because they hope some misguided 15 year old girl will think they are cool and go for a ride with them around and around the local fast food joint. Well then the answer would have to be it will never be big enough.
  15. Nic

    Nic TechSpot Paladin Posts: 1,549

    I think we wandered off the track a little. The real question was ...
    Well, there is only one way to find out, and that is by trying it out and listening to it. I think our discussion of the merits of amp/speaker size, distortion, etc., will play only a small part in the grand scheme of things, as the acoustical environment of a car, is not exactly the best place to listen to quality audio equipment. Providing each of the components balance out another's weakness (rather than adding to the problem), then it should end up sounding fine.
  16. Godataloss

    Godataloss TS Rookie Posts: 482

    Agreed- ultimately the enclosure will play the biggest role in the overall sound quality and when you install you should consider protecting your speakers by in stalling a polyswitch, light bulb, breaker or combination.
  17. erickdj

    erickdj TS Rookie Posts: 69

    There's a lot of arguing about clipping, line noise, and such things. Like I said before, I'm not an electronics expert or student as some of you. However, unlike a lot of "experts", I do have a high powered sound system in my car(>1000 Watts RMS). I have seen subs being burned out by an amp that clips so much that the speaker no longer seems to produce any "musical notes", instead it just made some random noises when driven into distortion. directorj17, compare your sub and amp to combining a hummer H2 with a 4 cylinder engine taken from a stock honda civic. The hummer will run, it will move. However, it won't have the adequate performance you would expect out of a normal hummer with a V8 engine. I noticed someone said "Who needs a 1000 watt sound system in their car?". Well, some people do like it, including myself. Just like some people prefer a 19" monitor over a 14" monitor. You can still use the computer with a 14" monitor and it will function well, but most people like it bigger and better. Not everyone that drives around shaking people's windows is doing it to show off or hope that they can "pick up" some teenage girl. Anyone that resorts to that has some serious issues. In fact, most of the people I personally know that have powerful sound systems have them because they like to enjoy their music on the road. Some of them commute to work 2 hours away from home, so they spend more time in their car than they do at home. director, I would suggest that you go to your local audio shop and ask them to demonstrate to you how a 15" L7 sounds with a 300 watt amp and how it would sound with an 800 watt or greater amp. Most of what people can tell you here on the message board won't make much sense until you see for yourself how the speaker sounds when properly powered.
  18. YingYang

    YingYang TS Rookie Posts: 19

    Let me clarify what I meant exactly. Yes, the wire will add some distortion to the signal but the distortion will be undetected by a good 99.999% of the population when in the less than ideal listening setting of an automobile. You do an amazing install, you have amazing equipment, you dampen the hell out of your vehicle and listen to it without the engine the at point, your wire may make a difference which is detectable to you. On the other hand, unless it is a blind test, I bet any sort of difference will be because you mentally want there to be one. This is exactly why you have to do a blind test; what you hear will be affected by what you want to hear.
  19. YingYang

    YingYang TS Rookie Posts: 19

    Do you think ~2200w just on the sub is enough? Maybe around ~9000w for competition burping. You're right, that's just my sister's system at the moment. :D

    First off, any vehicle that mascarades as a Hummer but is nothing more than a Tahoe frame with more plastic, should not ever exist.

    That being said...
    SPL is logarithmic. If you ever talk to some real hardcore home audiophiles, they always say "the first watt is the most important." You can achieve a maximum 3db gain everytime you double your power or double the surface area of the drivers; 3db may not sound like much but that is equivalent to doubling the sound output. He needs to double his 300w to 600w to achieve those 3db and 1200w to get twice as loud as that. Also, as said before, power handling is most enclosure dependent and I can easily rip to shreds nearly any sub with the wrong box.

    For most SQ purposes, 300w will be fine but a L7 is going in the wrong direction. There are a great number of far superior drivers suited for that role.
  20. erickdj

    erickdj TS Rookie Posts: 69

    humm, looks like we have someone who resorts to sarcasm when all else fails. Right, H2's should have never existed because "you" don't like them! Attention automakers! Ask ying before you produce a car! You can steer people in the right direction to car audio? $hit, when you say 300 watts is fine for a 15" L7 you're doing exactly the opposite.

    director17, stay away from these so called "experts" that do nothing more than confuse the hell out of others to make themselves look good, throwing theories about the flow of electrons in every strand of wire. A few years back when I was barely getting into car audio, I had to learn the hard way to ignore these bookworms that think that just because they took an electronics class in college they can impress others and look down on those who haven't. The only thing I agree with yingyang on, is that Sony car audio and stuff like jensen is crap. I'd recommend you take a look at the group, you can get to it from google. There you will find lots of people that have PRACTICAL knowledge about the subject, many of them work as installers and others are folks like you and me that like to do their own installs. Give it some time, one day you will know enough to give practical advice to others.

    ying, I'm done with you, so save it for someone who is interested.
  21. YingYang

    YingYang TS Rookie Posts: 19

    At least you noted the sarcasm. I fail to see where you must pump loads of power to a driver to make it sound good. L7s may need some power but 300w will be decent for the added low end extention that most people want.

    Theories? I'm sure that none of what was said in this thread could be produced in real world applications. Switching RCAs or maybe even using a DMM would be too complicated for anyone but an ivy league professor. Conductivity of wire means nothing either; any piece or pieces of wire that you just find lying around the house would work in this application. Don't have wire? Just tape a bunch of spoons together. It's metal, right?

    Oh yes, bookworms who look at the t/s parameters on a driver and know how they influence the sound of the driver. The ones who read all they can to better understand how acoustics work in different environments and varying conditions. Us who actually apply the knowledge we have by testing all the things we learned from reading and studying the subject. Is it all overkill for the normal consumer? Yes, not many people care to understand the BL curve of a subwoofer or how a motor works. Does that mean that you should just go to Best Buy, Circuit City, or some other chain of stores and listen to a salesman who is paid minimum wage and whose primary goal is to move inventory? No, you ask around and read up to the point where you won't get intimidated by some salesman.

    Ever go to or or even You have people there in the industry from companies such as Adire, Resonant Engineering, Elemental Designs, Better Audio, JL, etc. Termpro has world class competitors in Db Drag who regularly exchange ideas and advice.
    These are the same people who have worked all their lives in a field which they love and they don't hesitate to inform the novice audio enthusiest who wants more than "go talk to some installers." If you think having MECP certification means jack, it doesn't; every Best Buy installer is required to get certified, not to mention, some of the things in their study guides are completely wrong or misleading.

    Obviously, I am trying to inform the community as a whole and try not to base my knowledge on what a few Best Buy installers have to say.

    You want to know where my knowledge comes from?

    Loudspeaker Design Cookbook by Vance Dickason
    Acoustics by Beranek
    Audio Engineer's Handbook by Benson
    Acoustical Engineering by Olson
    Tech papers put out by:
    - Adire Audio
    - Better Audio
    - JBL
    - Richard Clark
    - Dan Wiggins

    I don't know everything but I'm not ignorant enough to say that you should just take my word as the end to everything. There is just as much misinformation on the internet as there is of credible information. If what I said is wrong, prove it. I told him how to get the best sound possible with that setup with my first reply; everything else was to augment that reply and maybe help explain some of the common car audio myths that novices propogate. :grinthumb
  22. Nic

    Nic TechSpot Paladin Posts: 1,549

    Maybe you should rephrase that remark. That explanation was simply a scientific one for yinyang's benefit only, as he claimed to know everything about audio.

    As regards practical experience, well, I've been an audiophile for over 25 years, I have a degree in electronics, I built my own speakers, and studied acoustics, some 20 years ago. I've listened to hundreds of pieces of audio equipment, and I've installed a small number of car audio systems in that time. I even agreed with your original comments here. However, you now seem to have resorted to attacking everyone else's views on the subject. That's not good and only makes you look bad.

    Simple truth is, different people value different qualities in their car audio, and in my experience, I am quite happy listening to 6 inch units and 40 watt amps. Anything else is overkill for me. If you want to feel the sound and have it cover all the background noise, then thats fine for you, or anyone else, but don't start attacking others just because they don't agree with you, or because one person attacks your comments.

    Everyone here is free to make their own comments and I'm sure the thread starter will be able to compare and reach their own conclusions.
  23. YingYang

    YingYang TS Rookie Posts: 19

    Didn't claim to know everything, just more than most. :p Also, I'm more car audio oriented and you're more home audio oriented. The listening situations are different and the equipment available is different. 1000w on a home system is overkill in home theater yet most of us car people run at least that just for the low end section of our systems.

    I was not disagreeing about the wire possible introducing distortion; I was arguing that it would be undectable to the vast majority of the population in the listening environment of a car. Is nic wrong? No, he has a valid argument that I don't believe applies as much to car audio as it would to home audio, if at all.

    Though, we both agree that although you can look at specs all you want, in the end, your ears decide. If this wasn't the case, tubes would have completely been phased out by now because of the distortion they add to a signal which gives that "warm" sound that most people describe.
  24. Godataloss

    Godataloss TS Rookie Posts: 482

    Yin Yang- I can tell you are entirely a car guy and I agree with you that the H2 is a ridiculous behemouth wannabe-schoolbus of a monstrosity. As per your recommendations for car audio, I feel that rather than endorse quality sound and practical systems, you have fallen into the uncontrolled arms race that is car audio- where everything is Sound Pressure Level and competition winners are the cars that are most likely to cause accidental defication and hemmoraging to those people that get too close to them while they pump music from 10 15'' drivers crammed into the trunk and powered by an arcwelder. I may be showing my age (30) here but it seems rediculous to say that wire interconnects dont matter
    and then to recommend that someone needs a thousand watts just to reproduce bass in a car- that's just silly and untrue.

    The whole bass boomer car culture is an affront to my privacy and to my ears. It is born of the same mentality that says "I need the biggest damn SUV around- and I wanna look like Arnold or Pdiddy when I drive it so I'ts gotta look like a HumVee but be alot cheaper cus Im gonna need to save some money to buy 24inch rims that will totally destroy the ride and make it handle like a wheel barrow, but hey- I'll look cool and women will like me even though its blatantly obvious I'm over-compensation for something."

    <calmly steps down off the soap box>

    as to the original post- a 300 wat amp will drive ANY 15 inch speaker to a level appropriate for listening to ANY music in ANY sized car- PROVIDED its x-over properly and in an appropriate box. Will it rattle your liscense plate? yeh probably. Will it rattle mine when you pull up behind me? probably not, but it will save you a finger gesture.
  25. Nic

    Nic TechSpot Paladin Posts: 1,549

    Well said Godataloss. I think YingYang's ears are already beyond recovery, and that is why he needs it louder and cannot pick out the details in the sound. No, I'm just kidding really, but each to his own as the saying goes. Besides most owners that are into high wattage car audio, do so for the bragging rights alone, and not for the sound quality. These high powered systems can be dangerous and damage your hearing. If you drive around with the windows closed, and crank up the volume, then decide to open the windows, you could end up bursting your eardrums as the SPL will suddenly increase beyond safe limits. That's something to bear in mind if you plan on going down that route.
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