build advice

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Originally Posted by alexe693

dude you are incredible! so if my sub is 2 ohms and the sensitivity is i think 92 db that means i should match my mids speakers to that too?

also i think im thinkin about buyin your 15 inch sub box you have on ebay

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For simplicity, yes, lol. It can get much more complicated when dealing with distances vs sensitivity as well, but for great output matching without worrying about exact dB levels for sound quality purposes, then yes, you have the idea. To get a set of mids that do 92dB though may cost a bit, lol. Im not sure, you may have to do some research on that. But here is the thing. The enclosure will add to the sensitivity of the output, but if it is located further away than the mids and highs, you should be ok.
As far as the ebay enclosure, that would be great! If you like, contact me through ebay and get me the driver specs through there, not on here, and Ill check to see what the sub(s) will do in that specific enclosure for an anechoic response.

soo i sort of have a problem, the 3000 watt, 1 ohm mono amp i have the opportunity to get for cheap is to much power for my single 15 inch sub. I want decent fuel efficiency and all around good sound soo i think drawing 3000 watts for one sub is too much for me, is there anyway to bring the power down so that i dont have to strain my car so much and so that i wont blow my sub? im looking at this head unit (Alpine iDA-X305SBT Package iDA-X305S digital media receiver and Bluetooth® adapter at Crutchfield Signature) to power my component speakers...

so what im looking for is alternatives to that amp or are there anyways to make that amp work for a single sub but not draw so much power if you know what i mean?

The sensitivity of the subwoofer is 100% not relevant to the application at hand. The testing manner used to find such numbers does not apply to a subwoofer or its performance.

You are far over reaching what you need to worry about at this stage in your build. Knowing more information is great, but when you are just starting try taking it easy and just work at it as you go.

Upgrading your source unit is a must and with the added amp/sub setup you will have to see how all that reacts in your car per your tastes. You may be fine with what you have at that point. You want more mids/highs or more bass. Once you are to this point then come back to see what better options there are.

I can tell you first hand that many things that are true and even the math/science behind it says its true..mean nothing once in an application. Unless you are going to compete in sound quality(which is 100% subjective to the judge...which I am one), there is not need to go to the extent being discussed. Not to mention most of it won't even be audible to 99% of the people who would hear it, including you.

Lot of good/decent info, but just not relative to the situation is all.

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Originally Posted by pro-rabbit

The sensitivity of the subwoofer is 100% not relevant to the application at hand. The testing manner used to find such numbers does not apply to a subwoofer or its performance.

You are far over reaching what you need to worry about at this stage in your build. Knowing more information is great, but when you are just starting try taking it easy and just work at it as you go.

Upgrading your source unit is a must and with the added amp/sub setup you will have to see how all that reacts in your car per your tastes. You may be fine with what you have at that point. You want more mids/highs or more bass. Once you are to this point then come back to see what better options there are.

I can tell you first hand that many things that are true and even the math/science behind it says its true..mean nothing once in an application. Unless you are going to compete in sound quality(which is 100% subjective to the judge...which I am one), there is not need to go to the extent being discussed. Not to mention most of it won't even be audible to 99% of the people who would hear it, including you.

Lot of good/decent info, but just not relative to the situation is all.

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thanks for the info, and your talking about the sensitivity posts correct? because my main problem is what type of amp to go with and whether or not i should power my speakers from the headunit or get a different amp and power them with that which would be more costly..

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Originally Posted by alexe693

thanks for the info, and your talking about the sensitivity posts correct? because my main problem is what type of amp to go with and whether or not i should power my speakers from the headunit or get a different amp and power them with that which would be more costly..

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Yes, the sensitivity posts is what I was talking about.


In your position, I would upgrade your source unit and see where that leaves you after installation. I know many people that use 1500(ish)rms and only use the source unit to power the mids/highs and they like the overall sound. For some others they like a little more control and blended sound so they end up getting an amp to push them. I would just get the new unit and go from there. You may very well be surprised at the over all sound you do get from just that one piece.

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Originally Posted by pro-rabbit

Yes, the sensitivity posts is what I was talking about.


In your position, I would upgrade your source unit and see where that leaves you after installation. I know many people that use 1500(ish)rms and only use the source unit to power the mids/highs and they like the overall sound. For some others they like a little more control and blended sound so they end up getting an amp to push them. I would just get the new unit and go from there. You may very well be surprised at the over all sound you do get from just that one piece.

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okay thanks for the advice and the straight forward answer. i think im going to take your advice but do you have an answer for my extremely overpowered amp problem? haha

I guess I'm being forced to be simple and less accurate,lol. So for that, I will subject myself to a simple answer for once......turn down the gain. Wanna know more.......too bad I guess.

I could talk about how you shouldn't use smaller wire for less voltage like some people do, but I guess no one but me cares about you catching your vehicle on fire or having a great setup,lmao.

I understand what you are saying, rabbit, but without calculations, no one would have an idea of where to start. And they are accurate enough now days to be very reliable in the field. Its those that have been in the field for a while that do not understand correct formulas that have given the audio community the subjective accuracy of theory. What people do not understand about formulas is they can be general, yes, but can also be utilized for higher accuracy. I'm not talking about simple box calculators and port calculators and crap like that either. Those, yes, I agree.....do not rely on them alone, but only to get a starting point. But once you get further into it, the calculations, being that sound is physical and physics are absolute in theory vs practical, can be very accurrate. There will always be a sense of fine tuning, but this is obvious, as vehicles are very tough to calculate to the exact frequency and dB levels due to the oblique shapes they have. But you would be amazed at how far you can go before any fine tuning is done.
I do not want to have to argue this again, but I will.

haha dude no way! I appreciate the detail and all the advice i can get! youve been great and im excited to see what kinda box you can put together for me! you have pretty extensive knowledge and its hard for me to keep up but id rather have it than not, i just have so many questions you know because i cant afford to buy an amp, realize its not gunna work out and buy a new one haha but doesnt the amp overheat when you dont use the full 3000 watts?

Awesome. As far as the amplifier overheating, this would be mainly due to mismatched impedances, meaning if you try to push a 1ohm load through a 4ohm amplifier at full power. The conductivity of the wire will determine part of the applied electrical input/output, but the resistance levels of the amp will determine the rest, in general. So, no, by underpowering the subwoofer or not using the full wattage, as it is relative anyhow, you would be ok as long as the impedance matches or is greater on the load side(subwoofer) than the min resistance on the amp. Distortion becomes a factor of what you question, but again, proper tuning will eliminate it anyhow. You could power a radioshack speaker with a 5000w amp as long as the voltage level and resistance matches. If anything, having an amplifier with more power than the sub can handle is better, because you do not have the need to drive it into distortion.

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Originally Posted by Moble Enclosurs

Awesome. As far as the amplifier overheating, this would be mainly due to mismatched impedances, meaning if you try to push a 1ohm load through a 4ohm amplifier at full power. The conductivity of the wire will determine part of the applied electrical input/output, but the resistance levels of the amp will determine the rest, in general. So, no, by underpowering the subwoofer or not using the full wattage, as it is relative anyhow, you would be ok as long as the impedance matches or is greater on the load side(subwoofer) than the min resistance on the amp. Distortion becomes a factor of what you question, but again, proper tuning will eliminate it anyhow. You could power a radioshack speaker with a 5000w amp as long as the voltage level and resistance matches. If anything, having an amplifier with more power than the sub can handle is better, because you do not have the need to drive it into distortion.

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perfect man your extremely helpful! so i guess ill go with the 3000 watt amp just because itll be the cheapest! the amp is a monoblock 1 ohm amp so i dont have to worry about it overheating i guess, the only thing i need to know is

A) its okay to wire a 1 ohm amp at 2 ohms to match my sub correct? my two reasons for doing this are that the amps output at 1 ohm is 3k so at 2 ohms itll be close to 1500 watts, is this correct?

B) am i going to need to upgrade my alternator to power this beast of an amp, the family member i got it from says he used a second battery but i dont know what the best option is?

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Originally Posted by alexe693

perfect man your extremely helpful! so i guess ill go with the 3000 watt amp just because itll be the cheapest! the amp is a monoblock 1 ohm amp so i dont have to worry about it overheating i guess, the only thing i need to know is

A) its okay to wire a 1 ohm amp at 2 ohms to match my sub correct? my two reasons for doing this are that the amps output at 1 ohm is 3k so at 2 ohms itll be close to 1500 watts, is this correct?

B) am i going to need to upgrade my alternator to power this beast of an amp, the family member i got it from says he used a second battery but i dont know what the best option is?

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Yes, you can definately wire the subs at 2ohms and it will give you the 1500w range. The best recommendation would be to research the big three upgrade first. A second battery is only useful when running the system with the car off. The alternator upgrade would be more plausible.

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Originally Posted by Moble Enclosurs

Yes, you can definately wire the subs at 2ohms and it will give you the 1500w range. The best recommendation would be to research the big three upgrade first. A second battery is only useful when running the system with the car off. The alternator upgrade would be more plausible.

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yes i definitely plan on doing the big 3 upgrade...is that all done with 0 gauge wire? and yeah over time i plan on switching to a deep cycle battery and probably getting a better alternator...this is all shaping up to be extremely expensive...not even including wiring and connectors and stuff...

Yea, it can get expensive,lol. But well worth it if you enjoy great music or ever want to compete. But as far as competing, my question is, as for pro-rabbit, if the judge is to be bias on the setup, why compete in the first place? it should be based on measured response and staging and placement, not looks or subjectiveness. Just a random thought. But yea, you should be good and are on the right track, alexe