Need help with the design of my sub and amp system

[boho2bizon]

I came to a conclusion that i need to install a sub in my car(Ford Cougar 1999 or in USA Mercury Cougar) as of right now i have an aftermarket head unit and speakers. The head unit is Kenwood kmm-bt205 and the speakers are 4 Hertz speakers and 2 tweeters (I don't know any details about them because they were installed by the previous owner). The speakers are wired to the head unit and I want it to remain that way. I'm thinking about two 10" subwoofers about 300W RMS each and 600W mono channel amplifier. I want to make custom enclosures for the subs and the space I've got is around 0.8-0.9 cubic feet for each enclosure without considering the volume of the sub. I spoke with a friend of mine who basically told me that I don't need two subwoofers (because my whole car would shake like crazy) and that my head unit isn't good for any type of sub/amp system because it has one RCA port with output voltage of 2,5V. My question is do I really need a head unit with 4V output is it really unnecessary to have two subwoofers and how budget should I go if I decide to go through with making the system? And also I'm open for any suggestions. I personally think I have some sort of above basic knowledge of audio but I haven't played around with subwoofers yet.

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[1aespinoza 10+ year member]

I spoke with a friend of mine who basically told me that I don't need two subwoofers (because my whole car would shake like crazy)

First of all, your friend is nuts. The more subs you have, the happier you life will be.

because it has one RCA port with output voltage of 2,5V.

You can always use an RCA splitter, no biggie. Most amps have a gain sensitivity of down to 0.2v. If you are not pleased with the output, you can just add a digital LOC for around $70.

is it really unnecessary to have two subwoofers

In a car's trunk 2 10"s is better than 1 12". The seatback will muffle quite a bit so more cone area is better.IMO.

how budget should I go if I decide to go through with making the system?

For sub stage I think $400 is a good starting point if doing the install yourself. This is based on looking at Bass Package deals.

 

[HardofWhoring]

You only need 1 preout for each amp. If you are hooking it up to sub amp, then you're good. I would look into what the preout is specifically for though. It most likely is for a sub in that it's an extra channel, and you can adjust some of the parameters before sending out the signal, such as a pass filter or volume boost or drop for that channel.

If there is a chance you might want another amp down the road, you could also look for an amp that has it's own preout. They all have signal in, but some have there own signal out (preouts on the amp) so that you are basically daisy chaining the signal. There's several other ways to solve it if you don't, but just a though.

As far as 4v, a higher voltage makes for a cleaner signal, but its for subs, so don't worry about it.

If .8-.9 cu ft is before the sub volume, is that also going to be interior size? We're getting small, and to the point where you really need to consider (1) 12", and at least do the numbers. Are you trying to go ported or sealed?

How did you come up with 300w rms? That's a small powered subwoofer. Are you wanting to feel it hit, or do you want a little bump that will help the sound quality of the music, and you aren't trying to upgrade your alternator or battery? Two 10s on 300w will NOT make your car shake like crazy. Two 10s on twice that and were getting close, but "shake like crazy" is relative.

 

[boho2bizon]

I would look into what the preout is specifically for though.

It's labeled as Rear/Subwoofer on the specs says its switchable and supports 2-way and 3-way x'over but I'm not entirely sure what does that mean.

If .8-.9 cu ft is before the sub volume, is that also going to be interior size? We're getting small, and to the point where you really need to consider (1) 12", and at least do the numbers. Are you trying to go ported or sealed?

.8-.9 cu ft is the interior size before the sub. I want a sealed box because it's easier to DIY imo and requires less maths and knowledge that I'm not sure I have.

How did you come up with 300w rms? That's a small powered subwoofer. Are you wanting to feel it hit, or do you want a little bump that will help the sound quality of the music, and you aren't trying to upgrade your alternator or battery?

I was browsing local websites that sell audio stuff and found 10" Hertz sub that is 300W RMS and is around 100$ which i thought is enough for me, my car and my wallet and also I was thinking 2 of them so overall 600W RMS. Also this car is my daily driver and it's not that I want just a little bump, I want to feel it hit but I'm not sure how much I want it to hit. I don't think I've spend enough time in a car with a sub system to know what I want. And I definitely don't want to upgrade neither the alternator nor battery.

For sub stage I think $400 is a good starting point if doing the install yourself. This is based on looking at Bass Package deals.

Is it okay to shop second hand stuff like this. I'm comfortable with buying an amp second hand as in my opinion is the more long lasting part of the system and it definitely doesn't have that much movement. But the subs I think are trickier to get used mostly because I need two identical speakers(i think) and also they are easier to damage in shipping or in removing them from the previous system and also if it's an older sub where do I get the specs sheet for it and how do I find out how much volume it needs from the enclosure.

 

[1aespinoza 10+ year member]

Is it okay to shop second hand stuff like this.

Most of my amps are second hand. They work great and I have had most of them for at least 8 years. Audio shops sometimes sell bass package deals that include all the equipment for a complete setup, so no need to get used gear. As for those Hertz subs you mentioned, that sounds like a good deal.

 

[HardofWhoring]

You never really know with amps. They could last another 30 years, and they could go out in a week.

Here's a place I always check for deals. They have a couple of low priced amps, and even a package right in that price range you mentioned for used. I have some hertz amps, and I like the quality, can't compare it to some of these other ones listed.

Sale

WoofersEtc.com - The Online Car Audio Superstore, the Largest Selection at the Lowest Prices!

www.woofersetc.com

Don't sell yourself short. If you're here doing research, you are ahead of most people. There is plenty of information to help you if you wanted a ported box, to hit harder.

The big 3 always helps. For electrical, here's how you can figure it out for yourself and see what you are working with.

amp wattage (lets say) 600 / amp efficiency( / .85 for usually 85% efficiency) = 705 watts draw for your amp to produce 600 watts.
705w / 14.4 (voltage) = 49 amp draw, when that is full on. You should know what your alternator is, and see what your factory options are. I know on my vehicle there is 105, 130, and 160. If you could find an alt that is about 30 amps more than what you have, then you would never notice the draw. Before you buy subs, I would suggest you look into larger alternators, just so you are aware of your options and see how it fits in your overall budget.
- If your lights dim, your circuit is not good enough.
- If after listening to it for a while, and your battery voltage drops, then your alternator isn't charging enough. It's something you should weigh your options before hand. Worst case is, you have to shut your stereo off for 10 minutes before you shut it off to recharge, (and that's if you have your lights on, your AC on, your turns on, play with the windows, are charging a couple phones, and really putting a strain on your factory electrical.

Building an enclosure is not difficult, but if you're on a tight budget, you might want to figure out how much materials cost, and what tools you would need to buy, and the time to design and build. If you don't have the tools, and any generic enclosure will fit, that will probably be a better option.

As for subs, if it has a part or model number you can look that up easy. Even if it doesn't have information, post it here. I'm amazed sometimes how some of the active members on here can look at a sub and tell you the power it wants even if it's a 30 year old sub.

 

[boho2bizon]

Thanks i will look into my options especially the alternator.