Axiom Home Page Forums General Discussion The Water Cooler Dumb car audio question

OK. I have been wanting to add a sub to my car for a long time now. I don't need anything crazy like dual 12" subs or thousands of watts of power, I am just looking for a moderately low cost way to get some sub power in there so that I have a little more thump, but not so that people can hear it 5 blocks away.

Anyway, I am looking at amps and have probably a stupid question.

Amp Channels! Mono vs. 2 vs. 4 channel... What is that all about? At first I thought that it meant output channels. Mono means one sub, 2 channel = 2 subs, etc. But other things I am looking at are giving me conflicting information, like a combo unit with 2 subs, and a mono amp. Then again there is parallel and serial wiring that tells me that as long as the ohms are within range, you could hook up whatever (within reason) you wanted.

Again, probably a rediculiously simple question, but I just figured it was easier to ask.

I am thinking just a single sub, but I am stuck on this amp thing.

DOH. I figured it out...

I had my "blinders" on and was thinking "Sub AMP" not general audio AMP. DUH! 2 channel AMP is for speakers (right/left), 4 channel AMP is for Right and Left combinations both Front and Rear...

Mono AMP is all that is needed for a sub.

GEEZ! <smacks head> That IS simple.

Maybe your online icon would turn a nicer shade if you stopped smacking yourself.

Yeah, first I was ticked about the HD-DVD/Blu-Ray thing a month ago, now I am ticked off about my damaged Axiom speakers... Maybe I'll change it to try to be a bit more "proactive" with my emotional state of mind.

There I "upgraded" from Mad, to Sad... <sarcasm> Woohoo... Life if getting better already... </sarcasm>

Still Winter in the midwest, eh Nick?

What kind of car?

Just a measly 1999 Ford Contour Se Sport. I've upgraded the head unit and the 6x8's a couple of years ago, which was a big improvement. I just want something a little more, not a lot more since this is just my daily to-and-from-work driver. There is a hole cut into the metal of the rear deck where some people have put in an 8" or a 10" IB sub, but I think that there would be better performance out of something inside a box with less cubic feet than my entire trunk.

I have a 10 inch Alpine sub with the Alpine 250 mono amp.

It doesn't overpower. It just sounds good.

Mine is housed in a box for my 2000 Suburban.

An 8 inch might do the trick for your situation.

HMMMM...... I think that WOULD make me change my forum mood from sad to very happy... Although I am not sure that it would fit in the trunk...

Oh, heck, I'll just strap it in the front passenger seat!

Nick, I had a '96 SE Sport. It was surprisingly entertaining to drive - zippy motor and quick reflexes in the corners. Way better than most of the numb sedans out there. Too bad the thing was plagued with gremlins. Near the end, it needed about $4K in repairs, but was only worth $2K. Ended up giving it to my brother inlaw. He dumped the money into it and then proceeded to wrap it around a tree. Nice going.

So what year is the Cutlass in your Avatar? My first car was a '68.....

It's a '68 as well. Not mine, but I love the pre '70's Cutlass's. (where's grammar bot?) My Dad had a '67 and I had an '81 in high school.

My wife is fully aware that once the kids are through school, I'm buying a 442.

I cut out those vertical "fins" in the front grill and installed driving lights. It had a 350 with a 4 bbl carb. I can still smell the sun-dried-out fabric...

New question.
Two 10" subs or one 12" sub?

Two 10" subs would cost 40% more than the singel 12" sub.
The 12" sub has 20% more RMS wattage than one 10" sub, but two 10" subs have 38% more watts than the single 12".

10" subs are 2.85 watts per dollar, and the 12" is 3 watts per dollar.

So keeping in mind that I want to supliment my low end car audio and not create a thumping monster, which should I go with? Or should I just put in a single 10" sub?

I know that this is a personal opinion question, but I've never had a car sub before.

Hi,

One sub is plenty. The volume of car interiors is tiny compared to rooms in a house. It's been years since I've written on car audio, but I have a sealed-box (acoustic suspension) sub, about one cubic foot or maybe a bit larger, with a 10-inch driver (Pioneer) and it's excellent. It was driven by a separate 185-watt bridged mono amp, which got intermittent. So I bridged the sub output from the other stereo amp. Some car audio amplifiers let you do that.

It works fine, but I'm out of touch about newer car amps. These are 15 years old.

Regards,

Alan

Nick,

I forgot to add that if you have the windows up, you can get amazing subwoofer performance in a car interior and for relatively little money compared to home subwoofers.

There are no standing wave problems because the sub pressurizes the entire interior, so any passenger hears the same powerful bass that you do. Subs for cars are all 4 ohms, so you can get more power efficiently from the amplifier. Sealed-box subs are inefficient so you want lots of real watts to drive them, but you get very smooth, tight deep bass to below 20 Hz from a well-designed sealed box car sub.

Alan

Thanks Alan. So that eliminates the thought of a dual sub for what I need. Now to figure out if 10" is enough, or if I should go for 12". The 12" will take up more space, but only cost about $15 more than the 10" I am looking at.

Oh, I was thinking that a sealed box was the way to go. More tight bass like you said, and the amp I am looking at is rated at 52% more (as is just more than 2x) RMS wattage than the 10" and 40% more than the RSM of the 12"... I have enough amp power anyway.

Wow that is so odd. I had a 68 HO.

Nick, I've had all different combinations over the years. Four infinite baffle 8", two isobaric 10", two sealed 10", four sealed 10", one ported 10", and two sealed 12". By FAR my favorite setup was the two sealed 10's. I found the 12's too sloppy and boomy. Great for 80's rap, but that's about it. The sealed 10's sounded good with just about anything.

As Alan stated, the interior pressurizes very easily. The key is having enough amplification for the REST of the system....

Thanks. That helps....

Now I just need to find a good priced box between 0.70 and 1.30 CuFt for the 10" sub... I could make one (I even have enough 3/4" MDF just sitting in my workshop, but honestly, I am up to my neck in projects at home that I am seriously considering buying one.

There is a difference with car audio subs. If you want SQ, you look for a sub with those characteristics. If you want to rattle your neighbor’s windows, you look for that. Seal boxes tend to be more musical as well. Thinking of boxes, careful design and fabrication is a MUST. They need to be rigid with the appropriate amount of volume for the sub you buy. Each sub will come with cubic feet requirements. And then of course power is another consideration. Amp design is vastly different. I wouldn’t go cheap with the amp.

My last install was around four years ago, and I have not kept up on car audio since then. When I did install the system (03 Dodge Quad Cab P-up), I used two, 10” Soundstream Van Gough subs and built my box out of 3/4” MDF with internal braising. I went through several different amps and ended up with two, 500 watt Phoenix Gold mono’s. The combination was very good. I think you can find the subs for under $150 each now and the amps can range anywhere from $200 to $400. I also opted for an Optima Yellow Top deep cycle battery and a capacitor for each channel. Some folks tell you to run a new alternator, but I disagree with that theory. Don’t forget running good wire and connectors. #2 depending on the amp current draw, or possibly #4.

You should also consider Dyno-matt everwhere you can. Just that alone can make a car's audio come to life.

Jeezus, Mike, is there anything you don't Over Kill?

2x$150 a sub +$300 for the amp = $600 + wiring + enclosure = $750

Remember, I just want to add a little bass. I don't want to go with the Walmart Durabrand or whatever, but I don't want to pay for JL either. Good information though Mike. Thanks!

I've done some looking into sub boxes, and locally I can only find crap, or expensive (overpriced) stuff.. I may just have to make one myself after all. SO if I have a range of 0.7 - 1.3 CuFt, does the larger box provide a deeper bass enxtension?

Nick,

Yes, other things being equal, a larger enclosure always provides deeper bass extension, but other factors intrude. I'll try and find the old article on my installation with the dimensions of the box and the driver model. The design was by the late Peter Mitchell, an audio guru and former astro-physicist who used to occasionally write a column for me on car audio. At the time, he was regular contributor to one of the US car audio mags.

Peter supplied the box dimensions and driver number and a kid from Pioneer Canada built it for me, the first person I ever heard use the expression "tricked out".

Alan

You could check with eD and see what they would have to offer. They are from out you way Nick, Newton Ia.

I wonder if there is a way to put all axiom 6.5" woofers and tweeters in a car?

Too funny Rick. I was just watching some of the eD videos on YouTube literally 5 minutes ago (about the time that you posted)...

I am finding all sorts of "guidelines" online about building a box.

Add at least 2 inches to the depth of the actual speaker for movement.
Depth = 0.7 x Width
Height = 1.4 x Width
Add 20% to cubic feet to allow for speaker itself
When in doubt, target the middle of the recommended cubic feet range.
Make sure that the finished sub box will actually fit where it needs to go.

So in my case, if the sub says 0.7 - 1.3 cubic feet, the middle ground is an even 1.0 cubic feet. Add 20% and you get 1.2 cubic feet.

Follow the math above, and a box 10.5" deep, 14.5" wide, and 20" tall yields 1.213 cubic feet.

I don't know if that will fit in my trunk, however. I'll need to mock something up and test fit.

Nick,

When I was doing this stuff as another "hobby", I found this forum helpful. http://forum.elitecaraudio.com/

If you think that was overkill, I better not tell you about the head unit and components I used Tom. But I have heard that I do get carried away from time to time.....

Has anyone every used the program WinISD for calculating box sizes based off of all of the specifics on the actual sub speaker that you are using?

It told me that the "optimal" size for the 10" that I am getting is:
Width 17.126"
Height 26.575"
Depth 10.866"

But that is like 2.862 cubic feet; more than TWICE what the maximum recommended box volume from the manufacturer is. I was told that it was a really good program, but the data doesn't seem valid.

Man, that's gonna take up your whole trunk!

Yeah, that is why I am thinking that their program is wrong...

What driver are you going to be using? You can use a smaller than optimal box and then use polyfill to make the driver think the box is larger than it really is. I did this with the dual 12s I have in my S10.

I purchased my box and amp rack from subthump .They have a good FAQ you may want to read. They are a small outfit and may be able to reccomend a proven combination for your needs.

Are you sure the units aren't centimeters?

Yeah, the program gave me:
Width: 0.435m
Height: 0.675m
Depth: 0.276m

I converted those to inches, and then dropped those numbers into a sub box volume calculator to get the cubic feet.

OK. So I got out my MDF and cut it into the size I wanted, but I didn't glue it up last night as it was getting late. Anyway, a guy I work with, who always has an opinion on everything, right or wrong (many times wrong), but he said something that got me thinking.

Where to install the amp? He was telling me that I could mount the amp right on to the sub enclosure to save some space.

Now I know that the really cool professional installs like to show everything off, but that is not what I am doing. I just want it to work.

Is there any reason that I couldn't or shouldn't put the amp right on the sub enclosure? Would vibration or heat be an issue?
If I put rubber washers under the mounting feet to raise it a little for air flow and vibration dampening would that be enough?

Thanks.

I've seen it done and it apparently didn't hurt the amp at all. The only thing I would be a little worried about is the ease of a would be thief to easily take the sub and amp in one easy swoop.

Yeah, but remember, I am driving a 1999 Ford Contour SE Sport... Woohoo. The coolest car ever! While it is "fun" to drive, it isn't the first place someone would look to snag a sub.

Seriously though Rick, thanks for the concern and the valid point...

At least not till they hear that trunk thumping away and believe me it is a possibility.

I have seen much worse cars stolen for even less.

Well I managed to get the new sub and amp finally fully installed and tested today. I ended up building a 1.054 cubic foot box for it so that after the 10" sub displacement, I ended up with exactly 1.0 cubic feet, which is what I wanted. My carpeting job turned out pretty good too and it was a nice little project. The biggest delays were the shipping of the gear and the box parts from partsexpress.com and then getting enough free time to wire it all up. The signal wires were fairly easy, but still took over an hour to run them do to a couple of hard to remove interior trim pieces for routing of the wires. The power was a HUGE hassle for a while. trying to find where to run it through the firewall took me FOREVER because I kept trying what ended up being "dead-ends"... In the end, it was actually pretty simple, but just took a bit of trial and error to find a workable spot.

Overall I am pretty happy. I don't have it cranked up all of the way at the amp or at the head unit, but I am getting some really nice sounding bass and have some control right from the front seat. So far, with it turned up louder that I would ever listen to it, and with some bass loaded music playing, I get no rattle noises outside of the vehicle. Again, I was looking for quality bass and not quantity bass.

While I didn't go top end by any means, my dumb little car still has (with the upgraded speakers, aftermarket head unit, amp, and sub) a stereo system work over $1000. Not bad for a car with a dealer book value of $2800.

I am only hanging on to this car because it is fun to drive and my oldest daughter starts driving in 2 months. My plans are to make this her car and I get something newer. Seems silly to trade up now just to need a cheap car in a year for her. Of course, I guess all of this fun audio really just ends up going to her, but that is OK.

Can you really build something accurately to the thousandths of a CF ?!?!?

Yup!

No, what I really should have said was that the box design (which volume was calculated on a computer) came out to 1.054. It would be pretty tough to get the actual volume to be that accurate, but at least the base model/design was right on the mark.

Pics, where are the pics?

Sounds like you put some thought into this, and as a result it turned out nicely.

congrats!

I have the worst stereo system in my jeep...... maybe I should think about an upgrade

My Civic's got an OK factory system, but when I was looking at replacing the speakers with the ones I pulled from the old car, I discovered all sorts of proprietary connections and speakers buried under layers of plastic and screwed together bits. Fergit it...

Still need to take the dash off and figure out why the aux-in connector isn't working. Anyone have a 2000-era Civic with an in dash changer and an aux in?

Anywho... nice project, Nick! Glad to hear that it turned out well. Pictures, please!

Pictures? Of a simple sub box plopped into my trunk? Naw.... I haven't even ever posted pictures of v3.0 of my home theater, and that is much more interesting that my car stereo install/upgrade.

Says who

v3.0 is vaporware and you know it

Cool project, Nick.

I changed the spark plugs in my 1994 Camry V6 this weekend. I'm pretty effing glad I only have to do that once every five years. I'll probably just pay the guy next time.

There's a reason why we mechanics have tens of thousands of dollars invested in our tools of the trade.

I am amazed at how much bass it blocked by the back seat.

Hey Nick,

Have you got the sub facing forward into the seat, or toward the back of the car?

Facing towards the seat (facing forward)... Should I point it towards that back of the car, away from the seating?

Yes, I would try turning it around. It will allow the drivers to breathe a bit, and acts just like a home sub in the corner with a "loading" effect. If you don't like the change, just spin it back around.

There are a couple of other things you may want to try that have worked for me in the past.

In the Cutlass, I removed the sound deadening material beween the seat & trunk. In the one Accord, I cut an opening in the centre of the rear deck and just put a dummy speaker grill there. In the second Accord, I did the same thing, but covered the entire rear deck with grill material. (I was geting older, and it was too nice of a car to see an actual speaker grill)

I'll try turning it around.

The back seat has a fairly rigid, hard compressed "cardboard" type material covering it on the trunk side. I won't mess with that at this point, but maybe in the future. My rear deck lid does happen to have an 8" hole in the metal that I could try removing the foam backing and maybe put a grill over it. Who knows. It isn't that it is bad, but just that it isn't as efficient as it could be.