I've made an unfortunate discovery about the C4; when I'm playing music with the window(s) down and/or the roof off...bass is GOOD; deep, powerful...it's what we want. When I close up the car, the bass diminishes substantially. All that's left is a mid "punch"...the "deep" part is completely gone. Open a window? Deep is back.

JL Audio monoblock amp, ported 8" sub. Any experience w/the? Work arounds? Thoughts?

 

It's cabin gain. You can try moving the sub enclosure around, turning it different ways, but unfortunately there is only so much manipulation you can do to it.

 

What about changing sub size (bigger) and going for a slightly different frequency? Has anyone gotten good strong bass performance from a C4?

 

A buddy of mine has a 90 coupe that the top never comes off. He installed a Rockford 5 channel amp with 100 watts for the sub. A 10 inch kicker in a slant box. The amp has a adjustable gain **** that is located on the console. He can turn the bass up so much it will hurt my ears. I actually have a amp for the Sony head unit and a separate amp 250 watts just for the sub same as above and I can rattle my teeth out lol.
Maybe call Crutchfield and see what they have to say.
Keep us posted
Thanks
Hawkeye56

 

Thanks for posting. My amp (for the sub(s)) is 700w at 2 ohms, so I feel that I have sufficient power. I can make a lot of noise too...but it's BAD noise, with the windows up. Roll one down? it's suddenly 10x better sounding. Is your buddies car and yours making GOOD, DEEP bass? The kind that sounds/feels "3 dimensional"? Or is it simply, really loud?

 

my buddies and mine can get just load if cranked way up. On mine I set the base more reasonable so you can detect the bass drums and bass guitar like a very nice home stereo.
I for one do not like the bass so loud it rattles the store windows that you drive by.

Are you firing the sub directly down to carpet or a noise suppression ? That will effect the sound.

 

Right now, the sub is firing straight up.

 

What is happening is that subs move air to produce sound. When the windows are rolled up the sub cannot move as much air as when the window is down. The windows being up presents pressure/resistance to the sub. This effect is more dramatic with ported and/or smaller subs.

 

Makes sense. So....more sub, then? Not ported?

 

The cabin of a C4 is small in volume, and most likely what you're experiencing is that other, high midbass frequencies are getting boosted by its volume and some other lower ones are getting rolled off because there's literally not enough space for a full wavelength to "fit" inside the cabin. Opening a window effectively makes your interior the entire world instead of a really small space. I doubt this, but it's also possible that the port's output is actually hitting your ears out of phase with certain frequencies and cancelling them out.

You definitely have enough power. Assuming we are talking about about sounds 30Hz and up, even an 8" sub should have no problem creating those frequencies. The first thing I'd try, because it can probably be done easily and cheap-free, would be to close the port on the box and see what that does. Typically this will create bass extension that goes lower, but gradually tapering off as it gets lower, vs a port that is tuned to reinforce a certain frequency and then does nothing at other frequencies. If that doesn't work, then the next approach is probably brute-force-with-equalization approach, in which you use EQ to boost the missing frequencies and cut the ones that are overly reinforced. This obviously involved the purchase of an EQ (at least), and time spent with a mic and frequency graph so you can see how to approach the EQ settings.

 

No matter what the setup is, 8, 10, 12 and even 15 inch subs will all sound much better with the windows down. The more power and/or sub you have you will get more sound pressure but thats still going to sound 10x different with windows down.

 

Yes I agree to try closing off the port temporarily. My box is not ported at all.
Thanks Hawkeye56

 

I have two 8s in the place of the rear speakers of my car and spent a bunch of time sealing them up as well as I could.. It gets loud, with pretty great bass. I also have like 900 to 1000w rms available for the 8s, which is more than enough for them. Personally, I think the issue with the c4 is that the cabin gain is higher at higher frequencies. So when I really, really crank on it, the higher frequencies drown out the really low stuff. Having a ported box is only going to exacerbate that unless your designed the enclosure and port for the cabin gain for your car (note that even most custom boxes that are many hundreds of dollars do not go to this extreme)

Another potential option is to open a sizeable air leak to the outside. You could cut some holes that go from the cargo area to open it up to the inside of the body, and install some diaphragms or something to keep critters from getting in and ****.

Unfortunately, audio is one of those rabbit holes that gets endless. It starts with a nice sub and amp. It ends with hideously expensive speakers that make you think you're crazy and scouring junkyards for early 2000s volvo c70s. If you know why I say that... Then you know... And that's what I'm running in my c4, lol.

 

My old truck was the same way. It very much is a function of available volume and how easily you can move it. That also had a band pass sub... sealed front and ported rear so it did some odd things that didn't make sense to other people at first. But it was pretty tight. It actually got boomy windows down. It was tight and blended in up to around 300hz windows up. The drumming on 2112 for example... windows down it all got muddied by the bass. Windows up it made all the rolls and hits really percussive like you felt it. Which I believe is opposite what you are saying is happening?

 

MY god....I'm a dumbass sometimes. Today, has been one of those many times.

The wire going to the sub pulled out of the amp. All of my bass was coming from my 6x9's...which...is why I had "no" bass w/the windows up. AgentEran was totally right that the effect is the same w/the sub hooked up; more bass w/the windows down....it requires a bass adjustment on the h/u of about "1" to compensate, windows down or up, but now with windows up, of course it's much better. DUH!!

I was driving w/my son today and we were talking about it and I reached around to plug the port w/my hand to see if that changed anything...there was no air movement at the port. Sorry guys.

 

Glad the problem is solved!