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I need help with my amp selection? Can I underpower a sub?

Discussion in 'Audio & Video' started by patwrik, Jul 21, 2011.

  1. Jul 21, 2011 at 9:15 AM
    #1
    patwrik

    patwrik [OP] Well-Known Member

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    Hello all,
    I am looking to fix up my audio system in the truck. Not looking for anything extravagant or expensive, just something better than stock. Here is what im planning.


    Headunit: Clarion CZ501 *Already have*
    Front comps: Image Dynamics CTX65CS 100wrms
    Reer: Stock...running from HU
    Sub: Clarion WF2510D or WF2510 300wrms


    Now my question is, what 4 channel amp would you recommend for this?

    I've been looking at Pioneer GM-D9500F?
    75 x 4 @ 4ohms
    200 x 2 @ 4ohms bridged.

    Would this be a suitable amp for what im planning on purchasing? Anything you would change out?

    The reason i'm going clarion on the sub is that it is a shallow mount and I can get a pretty good discount on one. But, will I be selling myself short by under powering it? What can i expect by under powering it by 100wrms?

    Looking forward to your replies. Thanks!
     
  2. Jul 21, 2011 at 9:17 AM
    #2
    Yoytoda

    Yoytoda The Little Truck That Could

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    what are you going to run off the amp. just the sub? if so, then id just get a single channel amp
     
  3. Jul 21, 2011 at 9:37 AM
    #3
    AKtoyTaco

    AKtoyTaco Well-Known Member

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    I worked in the car audio industry for about 6 years & have a lot of experience w/ car audio systems of all kinds. In any application you are always better off giving a speaker/sub more power than less power. Think of your sub as 35" tires & an underpowered amp as a 4 cylinder engine. Will it work, yeah, sure. Will it perform as well or have as much power as either smaller tires or a more powerful engine? No, not really. You also have to think about the life of your amp. The amp will be heavily loaded & will struggle to supply the power that the sub wants. When an amp struggles to keep up with it's load it will start to lose control at higher volume levels, this is called "clipping". Basically your amp works as a funnel; the power comes into the amp on the wide side of the funnel & the amp controls this power & releases it to the speaker on the thin side of the funnel. If you over run the amp it loses control & loses the ability to regulate it's output to the sub, so instead of a funnel, your amp becomes a straight line hose with no control over it's output. In extreme situations I have seen overloaded amps (overloaded w/ impedance as well) fail completely & pass through raw DC current to the speaker. This will destroy your speaker in short order.

    The bottom line comes down to your expected use, listening style, & budget. If you plan to keep the gain on the amp at low to moderate levels, & plan on using the sub to give you a little more kick, then going w/ a 200w bridged 4 channel amp will be fine. If you really enjoy deep rich bass and/or listen to rap music or other bass heavy stuff, you will definitely benefit from a larger amp. That being said, you may have better luck w/ two 2-channel amps if you have the space as big 4 channel amps get expensive fast. Also explore options on Craigslist as you can often pick up good deals on used amps. The amp you have your eye on will definitely work but it won't make that sub sing like a larger amp. As a general rule you are better off running a 1,000w amp to a 100w speaker than you are a 100 w amp to a 1,000w speaker as ultimately the amp has as much if not more to do w/ final performance.

    Hope that helps.
     
  4. Jul 21, 2011 at 10:06 AM
    #4
    Amo-cat3

    Amo-cat3 Wizard Sleeve Master

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    i had the same set up as you with the id ctx components and gm9500 amp with an idv10 sub. The amp is pretty good for it being so small and can fit nicely under your passenger seat. It pushed the component speakers nicely but not enough juice for the sub to keep up.
    I was like you and didn't need anything extravagant, but i should of listened to all the threads that said to get a little more rms to push sub(lower rms sub should be ok with this amp though). So i bought a bigger amp and now have the gm9500 sitting on my dresser with only 20 hrs of use on it. My system is lively and clear now. (I'm more sound quality then loud thumping.

    My 2 cents to you is don't underpower your system because you'll end up buying a bigger amp. A little headroom with rms power will help make tuning and balancing your system easier and knowing that you have extra power to spare will help curb the "what if" syndrome.
     
  5. Jul 21, 2011 at 10:11 AM
    #5
    fishntaco

    fishntaco Well-Known Member

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    I think the JL XD500/3 might be a good amp for you. Small and enough power for the speakers and sub.
     
  6. Jul 21, 2011 at 11:03 AM
    #6
    mattg43

    mattg43 Well-Known Member

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    No. Not at all.

    Comparing the sub to a tire with a 4cyl? More like saying if you have a 1000hp engine that if you drive below a certain RPM it will blow up the engine.


    A sub does not "want power", or "require" anything. It is an inanimate object that turns the output of your amplifier (in watts) into sound waves. It will doe this with 1w, or thousands of watts (probably not for long..;))

    In fact, a speakers "efficiency" is rated with 1 or 2 watts. The 87db (or whatever) efficiency is a rating of how loud the speaker is with 1w of power at 1m, or 2.8Xv (2w) at 1m.

    So the thing will easily function with low power.

    The "issue" with underpowering a speaker is a personal thing. People tend to want a loud thump/bass/bump/etc. They tend to turn things up to get that level. If your amplifier cannot supply enough clean power to give to the sub (who has no feelings at all about this...) it will begin sending distorted signal to the sub, which typically will cause it to overheat, damaging the speaker.


    Dumbing it down a little bit. With the logic that underpowering a speaker blows it, would everyone in the world not blow their speakers when they turn down the radio? I mean, you are feeding the drivers with less power than they can "handle", so it would blow them, right?

    http://www.diymobileaudio.com/forum/car-audio-truth-myths-industry-dogma/93665-underpowering.html
     
  7. Jul 21, 2011 at 9:53 PM
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    patwrik

    patwrik [OP] Well-Known Member

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    Thanks for the replies guys...

    The consensus I get is that, while i can under power the sub, it probably isn't what I'm gonna expect sound wise. I guess ill look for another amp.

    Amo-cat, what amp did you end up with?
     
  8. Jul 21, 2011 at 10:37 PM
    #8
    pinktaco808

    pinktaco808 Hot Steppa

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    how much you wanna spend?
     
  9. Jul 22, 2011 at 3:34 AM
    #9
    patwrik

    patwrik [OP] Well-Known Member

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    +/- $200 bucks for the amp.

    I was looking at this amp. Cadence Xa1754B

    Should fit the bill. Don't know much about Cadence, but I can't find anything bad to be said on the interwebz.
     
  10. Jul 22, 2011 at 6:07 AM
    #10
    dolbytone

    dolbytone Well-Known Member

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    You're completely misrepresenting the scenario where underpowering a speaker can cause damage.
     
  11. Jul 22, 2011 at 6:45 AM
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    mattg43

    mattg43 Well-Known Member

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    No, I am honestly representing that underpowering a speaker will never damage it. Physically impossible. Mechanically impossible. Literally impossible.

    As stated above, and in the link - people tend to want more thump, so they crank the gain on their amps, or turn the bass boost on their head units up, and turn it up.

    The amp can only put out so many clean watts. If you turn it up past that point it will still output power, but in stressing the components it will start to send distorted power (there are pictures of this on a scope in the thread linked). Distorted power (square waves, etc) are essentially a rough spike of power, which can cause problems with excess heat the sub is not designed to handle, which damages or "burns" the VC, ruining the sub.

    Lastly, the example above is correct. If too little power blows speakers, then turning your music down would blow speakers.
     
  12. Jul 22, 2011 at 6:53 AM
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    Big D

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    you'll be fine. if the sub is new it'll have to go though a break in period first and may not be as loud. but after a week or so should sound fine if in the correct box. if not try wiring it out of phase if the amp doesn't have a switch for that.
     
  13. Jul 22, 2011 at 6:54 AM
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    mattg43

    mattg43 Well-Known Member

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    I dont know that its the wrong amp for you. If you want a sub to fill in and know that it will be there, its probably perfect. Remember that doubling power will give you a 3db increase in output. 3db is the generally accepted level that a human can differentiate a volume change. This means you would need ~600w to get a noticeable increase in volume vs the 9500.

    Next, remember that the amp in question is conservatively rated. Independent testing found that thing exceeding its power ratings at 12v, so it is able to put out a bit more power. Not a big deal, but I would estimate it to do about 90w X 4, and about 325-350w when bridged.

    Another way of thinking about this -

    The sub is rated at 83db @1w/1m

    So it will produce
    83db with 1 watt
    86 with 2
    89 with 4
    92 with 8w
    95 with 16w
    98 with 32w
    101 with 64w
    104 with 128w
    107db with 256 watts.

    You will also get to take advantage of cabin gain, which will increase the volume inside an enclosed space (your truck).

    If you want louder, a better option is to find a sub with a higher sensitivity, or more power to the equation.
     
  14. Jul 22, 2011 at 7:34 AM
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    dolbytone

    dolbytone Well-Known Member

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    Look man, I don't really want to have to get into this entire conversation again with someone. I'm just basically saying that when taken literally, the statement that too little power blows subs always gets someone going. When someone says an underpower situation blows a speaker or amplifier, they are not speaking in literal terms and picking at it is misguided.

    So the problem is that nobody explains what is really happening and both sides have points to add to the conversation, but the real answer is parts of both points of view. For now let's just say that the implementation of an underpowered speaker depending on what the user does when setting up and listening can lead to a blown speaker and/or amplifier. It's not the speaker's fault, not the amp's fault, it's the guy that chose equipment incapable of satisfying his/her listening demands.
     
  15. Jul 22, 2011 at 8:22 AM
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    mattg43

    mattg43 Well-Known Member

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    The problem is no one explains it.
    I dont want to perpetuate a myth because I dont want to explain it, so I take the time to put out the correct information.

    I am not "getting into it" with you. I didnt ask you to "have this entire conversation with someone again". If you have info, put it out there. If not, let it go. The info is correct, we both know it. You can argue semantics, but what I have posted is correct.
     
  16. Jul 22, 2011 at 1:03 PM
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    AKtoyTaco

    AKtoyTaco Well-Known Member

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    I love how threads like this so often break down into a pissing contest; who's right & who's wrong...

    the bottom line is that we're all essentially right. It's just looking at the same situation from a different angle. mattg43, yes, you are right in stating the fact that "underpowering a speaker will never blow it". Technically speaking anyways. Yes, in a lab you could run 1w of power to a 1,000w sub forever and the sub would never blow up. But in the real world someone who buys a 1,000w subwoofer expects the thing to pound. So they jack up the Loudness button, and they jack up the Bass control, and they jack up the gain on the amp, and they jack up the EQ, etc etc. and before you know if the amp craps out and sends a shitty signal to the sub which blows it up. Was this the sub's fault? no. was it the amp's fault? no, not really. it's the guy who buys a badass sub, underpower's it & expects to win an SPL contest's fault. If used correctly you can easily mix and match components and they will last forever; if used correctly. The problem is that the average subwoofer customer wants to crank up their system and hear it pound. And even if the system fulfills their needs for the first 6 months, they grow accustomed to the sound and gradually want more. So they start tweaking their system to get more and more out of it until finally they reach the breaking point of any one component and then the domino affect sets in and you start blowing up other pieces of gear.

    can you blow up a subwoofer by underpowering it? technically, the answer is NO. In the real world, do people destory both subs and amps on a regular basis by expecting too much from their gear and abusing them? YES.

    I've seen people run subs off of deck power... and they work just fine. just don't expect it to rock your world. Make sure your expectations are in line w/ your budget and your equipment.
     
  17. Jul 23, 2011 at 10:53 AM
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    Big D

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    when a sub, speaker whatever has a minimum of 50watts an rms of 300watts and a max of 600watts .that means 50watts to get acceptable sound, 300 is the maximum amount of power they recommend you use to run the sub all the time. 600 is the amount the sub can take for a brief period of time. 30 seconds or less. so anything between say 50 and 300 watts rms will do just fine. a little over powering wont hurt most subs but only if its clean and clear of distortion. thats the real killer of a sub.
     
  18. Jul 23, 2011 at 6:29 PM
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    platinumb

    platinumb Well-Known Member

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    x2 yup its not the low power that blows the speaker the reason people who under power speakers blow them is because they are trying to make the underpowerd amp run the speaker lowder than it is capable. and yeah that produces distortion and then blown speaker. if you neveer over work the amp you can run a jl 13w7 with the amp built into a pioneer deck but you cant try to get the output that youd get by running it with a 1000 watt amp.
     
  19. Jul 23, 2011 at 8:00 PM
    #19
    Amo-cat3

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    I ended up getting the MB Quart onyx 4.125 and it seems to be the perfect match for my system. My ID ctx components are much brighter and mid bass is better. My idv10 is frickin awesome, it is very clear and can thump pretty hard. The gains on my amp are turned only half way.
     
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