Q's about Subs

I

imported_Intel486

New member
First off. I hardly know anything about sound systems so the questions should be basic for even the slightly experienced people



I want a couple of 8" or 10" subs for my truck. They are going to go under the back seat. I'll need an amp too. I listen to rock but I sometimes like to do the rap music. In other words. I want something that can sound good for rap but something I can blast the bass of rap on. I have a couple of old 300watt sony towers in my house. Not sure what kind of subs are in them but I'd like bass quality like that. They sounds good for rap and rock.



I'm not going to mess around with chaning my Mid-range speakers right now. Subs first, then I'll get mids later. I can live with stock for another month or two after I get subs. I already changed the head unit out some time ago so I don't need one.



I'll need an amp for the subs then too.



So, what do I need to look for in Subs to get the sound I like? Can I get some general information on subs? Like what do all the ratings mean?





Also, I was thinking of getting a friend to help me build my sub box since he's built a few. I was wondering if you have to carpet the sub box?



I was thinking of after building it, doing all the prep work on the wood and then painting it the color of my truck. How can I do that and still get good sound out of the sub? I heard you need the carpet to get good sound.
 
www.crutchfield.com has everything you need.



OHM, is the resistance of the speaker. You would be best off with 2 12" in a custom enclosure, make sure the sub, has enough room to "breathe" or get a special sub meant for tight applications. Also, you will have to get high levell inputs on your amp is you have the stcok stereo, and run them off the rear speakers. Also, you should get an adjustable amp so you can control the bass level.



Go with rockford fosgate, really good, and kicker is awesome too, find the comprimise between your price and sound! DO NOT SKIMP ON THE AMP!!!!!! And use the BEST WIRES!



Kennwood and Alpine amps arent bad either.



You NO NOT NEED CARPETING!



Again see if the subs require a minimal "enclosure space" and wether or not they need to be ported or not.



Hope this info helps,



Alex
 
A forum that may be of some use to you is



http://www.sounddomain.com



also read and reread



http://www.eatel.net/~amptech/elecdisc/caraudio.htm



I know I am going against the grain on this one but...



Expensive cables don't always means good sound quality. However, I would suggest getting the proper gauge of wire for the power connections to your amp. But don't get those power cables that contain finer strands. Sound quality will not change, only the weight of your wallet.



Save the cash for a proper installation (hard to find sometimes), Or do it yourself if you have the time and have researched it well can keep the cash.
 
A sealed enclosure will produce tight, punchy bass. Sealed enclosures are best suited for rock, classical, jazz, or any other music where sound quality and accuracy are the top priority. The drawback to a sealed enclosure is they are not as efficient as a ported enclosure. Given the same amount of power, a sealed enclosure will not play as loud as a ported or bandpass box will. Ported boxes are used when the loudest, deepest, Earth shattering bass is desired. Rap music is best paired to a ported box because of the extended bass hits. The drawback to a ported box is the sound quality. Because there is no air pressure on the back of the woofer helping to control its motion, sound quality suffers.



A sealed box is likely your best bet, as they can be small and you won't need to worry about tuning a port or finding an acceptable location to place the port.



As for the ohms, an ohm is a measure of resistance. Without getting into it to deep (read Ohm's law and all that stuff) you will need to decide how much power you need to send to the subs. Lets say an amp is rated at 50 watts RMS into 4 ohms. If you took two 4-ohm subs and wired them in parallel, the ohm load presented to the amp would be 2 ohms (Ohm's law). At two ohm's, the amps rated power output would be doubled. Wire the same subs in series, and the ohm load presented to the amp would be 8 ohms. At 8 ohms the amp would be putting out around 25 watts RMS.



It is VERY important to make sure your amp is rated to handle the ohm load you present it with, otherwise you will have a crispy critter.



The best advice I can give you is to find a knowledgeable car audio shop, and let them give you advice and guidance. You will probably pay more than you would on the internet, but the knowledge you will gain will be worth it in the long run.



A good car audio shop MUST have install techs that are MECP certified. Another good indicator of a competent shop is one that solders all connections. Walk away from anyone that uses crimp connections.
 
RMS power refers to the Root Mean Square of the power. The term that should stand out in RMS is "mean". RMS power is measured over time (unlike instantaneous/peak power). It is sometimes referred to as Continuous Power.





So what this means in the context of that subwoofer?



The amount of power that the sub can continously draw is 300 watts. That means you can use any amp that is rated to deliver power up to and including 300 watts. Don't exceed that.



But thats not the end of it.



The impedence of the subwoofer will also have a great affect which amplifier you can purchase. The speaker is made of a cone that is connected to a coil. The coil, when current flows through it, will produce a magnetic feild that reacts to the speakers magnet. This causes the speaker cone to move. Dual voice coils means you have two coils that work together instead of one.



The resistance and the inductance of this coil form the impedence (the value of ohms you see).



So why have two voice coils?



You have a lot more control of the impedance. You can connect the coils in series. This adds the impedences of the two coils together. Or you can connect the coils in parallel which will make the impedence of the subwoofer equal to 1/2 that of one coil.



It is preferable to connect the coils in parallel. The lower the impedence, the more current gets drawn. This will therefore give you more power. If you look at amplifier specs you will see that the rated power will drop with respect to impedence draw.



So what do you need to worry about?



You need to get an amplifier that can has a rated total RMS power equal to or less than the rated power of the subwoofer, at an impedence equal to half the impedence of one voice coil.



In your case an amp with a rated power of <=300W RMS at 1ohm.
 
You may have a hard time getting an amp that is rated to 300W at 1 ohm (I would suspect it will be expensive). Many amps can handle 2 ohms. So maybe you should look for a sub that is dual 4 ohms/coil.



That is, unless you are getting a pair of these speakers. Then you can connect each speakers coils in parallel (1 ohms/ speaker) and then connect the speakers together in series (1+1 = 2ohms together). But then the maximum rated power your amp can be is 600W RMS at 2 ohms.



BTW, don't get the idea you need to get an amp rated for only 600W. Any amp smaller than 600W will work. You don't want to drown out your other speakers. But for future-proofing the system, just get one that is close to 600W and turn the amplifier's gain down so the sub's not so loud.







Another problem you worry abount is the space requirements. Look for suggested enclosure size that is as small as possible . This one suggests 0.8 cu. ft. per speaker. Thats pretty big; your truck may not fit two speakers in a 1.6 cu. ft. box.
 
Iceni said:
Another problem you worry abount is the space requirements. Look for suggested enclosure size that is as small as possible . This one suggests 0.8 cu. ft. per speaker. Thats pretty big; your truck may not fit two speakers in a 1.6 cu. ft. box.
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yhea, I've kinda figured that. I'm either going to spend $100 and get a lift kit and lift my back seat up or, since no one sits back there, I'll just leave the seat folded up.



So the speakers I listed are good high quality speakers that will deliver the sounds I'm looking for?



Say I get two of them, can I get a recommendation for an amp that will handle them?



Thank you for all your help.



BTW. I won't be attempting to install this stuff myself. Isn't that a good idea :D
 
I really don't care much about those boomy cars that drive by my bedroom at 3am. They soured me to the whole experience of car audio. I do have a system in my car but only improving sound quality.



That is why I can not make a recommendation on amplifiers; I simply don't have the broad experience. Nevertheless, I can tell you a few things that I know about amplifiers in general:



1.) Most companies apply similar measurement techniques in determining their figures for power and so on. However, I know that some of the cheaper companies use hype. Their power measurements are done at a much higher distortion level. Stick with a reputable name in car audio like Rockford, Alpine, MTX, JBL, Blaupukt, etc.



2.) Amplifiers are inherently inefficient. My amp (like most of the ones out there) is a Class A/B and it is only 64% efficient; that means 36% of the power it draws from the battery in primarily turned into heat. Class-D amplifiers, on the other hand, are much more efficient (in the region of 85% - 90%). This means you can place it in a badly ventilated area like under your seat and it won't burn your car down.



3.) Subwoofer signals are mono. That means don't buy a multichannel amplifier. Stick with a mono amp that feeds to both subs at once.



There is no wrong amplifier out there for the most part. Get what you want for the price your willing to pay but don't let a salesman scam you into a more expensive model because it will sound better. The human ear can only pick up low frequency distortion when it is above 10%.



Hope that helps.
 
can I get a recommendation for an amp that will handle them?
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I would recommend PPI or Xtant, both push real hard, giving you the bass you are looking for. I have owned both, I had a PPI running 2 12" Kicker Comps, and the PPI just pounded when need be, it's a great amp for bass, but you sacrafice some sound quality.



I have a Xtant in my car now, which pushes real good, probably very close to the PPI but the sound quality is so much better in the Xtant, there is no comparison.



If you want some real kick *** subs, check out JL Audio, they make some of the greatest subs I've ever heard.
 
Iceni said:
turn the amplifier's gain down so the sub's not so loud.
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:nono Amplifer gain is not used to control the volume of subs or any other speakers in any way. That is NOT what a gain control does. If you don't understand how to set clipping levels, please let a shop do it for you.



Sorry, just a pet peeve. The gain control is one of the most abused and misunderstood controls in all of audio.
 
Since Aurora mentioned JL Audios, you might want to check their Stealthbox line. I believe they have one for the F-150.



As far as amps go, besides the 2 that Aurora mentioned, I would also look at JL Audio there as well.
 
Thanks for the info.



What are some other online retailers of Subs? I think I've found two and neither of them had JL stuff.



PrinzII, I've seen a lot of boxed for the F-150s that fit under the backseat but they are all 8" subs. That is all you can fit under the back seat without lifting the seat but I'm not gonna pay $100 for a lift kit on a truck I might not have in a year.



laynlow said:




:nono Amplifer gain is not used to control the volume of subs or any other speakers in any way. That is NOT what a gain control does. If you don't understand how to set clipping levels, please let a shop do it for you.



Sorry, just a pet peeve. The gain control is one of the most abused and misunderstood controls in all of audio.
Click to expand...



Not going to be installing it myself so it doesn't matter but what dose the "Gain control" do?
 
I use to compete in IASCA and do the hole sound quailty thing a few years back. To this day for subs I have stuck with JL subs and PPI amps. I have had 4 sets of JL's from 10' to 15' I loved them all for differnt reasons. I would recomend them.
 
I have a factory JL box with 3 10" JL subs and a PPI 400W amp that I might be selling soon. The box is sealed and everything is in excellent shape, if not mint, and always performs flawlessly. And, this rig can go from ground pounding to punchy to quiet, depends on what you want it to do! If you or anyone is interested I might throw in the Monster Cable interconnect cables for free. I'm not sure if i could extract my power and ground cables, but I could try....they are 4 gauge, made to handle and flow high current. Just thought I'd throw this out there since I'm probably gonna be selling my car soon....



Anyhow, I'd still recommend JL and PPI to anyone. This combo is very versatile and loud! I sure have enjoyed them in my car!!



Here's a pic: http://mls77.homestead.com/files/DCP_0010_2.JPG



:)
 
Intel486 said:


Not going to be installing it myself so it doesn't matter but what dose the "Gain control" do?
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The only purpose of a gain control is to match the voltage coming off the head unit to the input of the amplifier. If you have shopped for a head unit lately, you have probably seen manufactures touting pre-amp outputs ranging from 2V to around 6V. Some are higher, others lower, but that is not relevant. What’s important is to make sure the gain is properly set on the amp for each individual head unit.



Generally speaking, the more voltage a head unit puts out the less prone the signal will be to pick up interference from other vehicle electrics en-route to the amplifier (good quality interconnects help here too).



If you set the gain on the amp too low, you will not get the full benefit and impact of what your system has to offer. If the gains are set too high, you run the risk of overdriving your amplifier and damaging your speakers through clipping distortion.
 
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