i'm running a rockford he2 sub (400/800) with a rockford 250.2 amp to my stock head unit and speakers. The problem i have is that the bass seems too boomy. what do i need to do make the bass more tight, like a bandpass box. oh yeah my sub is a 1 cu ft sealed box. thanks

 

Actually, boomy is used to describe the subjective sound of a bandpass enclosure. If you want the "tight" sound, use a well sealed enclosure. Sealed enclosure will be able to play transients a lot better. Maybe lowering your crossover point on your amp will do the trick.

 

what would be a good crossover point? i currently have it set at 60

 

I set mine at 80

 

Is the RF amp a two channel one? How many watts RMS is it? If it's powering the sub only, then I'd set it at 100Hz, since you still are running the factory deck and speakers which is probably why it sounds the way it does. You'll be surprised how important midbass is (100-350Hz region). The factory speakers are probably distorting because the bottoming out and the the amp in the stock deck is clipping. You gotta keep midbass out of those stock speakers to keep your midrange and highs clean. 60Hz is way too low.

Keep mind that for each octave lower a speaker plays, it needs twice the amount of power to move the cone. The stock receiver probably puts out maybe 10 watts or so RMS tops with up to 10% THD. The speakers can't keep up either.

Sub bass is so easy to achieve in a car, but if you want killer midbass, you need the right speakers, pleanty of power going to them, rerun wire to them and dynamat extreme the hell out of the doors.

I think you need midbass to get that tight sound your after.

What type of music do you listen to? Or what were the last 3 CDs you bought?


[Modified by dc24me, 11:51 PM 10/6/2001]

 

dc24me- its a 2 channel amp and i have only one sub in a sealed box. i don't really understand the midbass you're talking about, but listen to mostly hip hop. i'm looking for a setting where the bass isn't so floaty? can't really describe it. all i know is that the bass isn't hitting and then stopping, it kinda carries on. i don't know if you understand what i'm trying to say. well i'll try 100 thanks.

 

What he is sayin is that you need to cover the whole range of sound. Your stock speakers can not (may not) cover the mid ranges sounds, even if you run crossovers sometimes. Some stock speakers just can't handle it. Your sub produces the lows, and your stocks struggles to produce mids, and therefore makes the sound muddy (clipping notes). You may think it's the sub, but it's really the mids.

Like your engine, everyone talks about the high end for top speed, or low end to launch the car. But the mid ranges are the most important because those are the rpms that will get you our of a turn, pass on the highway, and most of your day to day driving.

Generally rear 6X9 is what covers the mids. But if you are going to swap them, you might as well do the front speakers too. And maybe a new HU too? I know, the cost is adding up.

 

which way is the sub facing... if it is facing toward the rear it tends to be boomy face it toward the rear seat and it sounds cleaner and more clear.. hope that helps

 

Well, I 'm pretty new to car audio, but I have been into home audio for a while now, and here's a tip.

If you turn your sub down a little (you did say it was an active sub, so that should be possible) and set the crossover higher, your bass should get tighter. At first you're going to think that your sound is not as full as it was before, but as time goes on, you'll notice that the bass is a lot quicker and more defined.

I'll try to explain what's happening. Most of us actually turn the bass too loud in our music. An actual flat 20hz-20khz sound spectrum actually has a lot less bass than the levels that we set in our systems. Since we usually turn our sub's bass level (from 20-80hz) too high, it overpowers the rest of the audio frequencies, including the range from about 80-200hz. This frequency range is key in lending definition and clarity to bass notes. So, by turning your sub down and setting the crossover higher, you're lowering the 20-80hz range. Your music won't sound as loud with the sub turned down, so you'll find yourself turning the music a little louder. This'll raise the 80-200hz frequency range (as well as the rest of the audio spectrum) and provide the clarity you need. One downside of this is that your sub won't seem to hit as low as it used to, but technically, it'll be more accurate bass.

The best way I can think of to demonstrate this is to go listen to properly set-up high quality floorstanding speakers (such as Paradigm, PSB, B&W, NHT, etc.) without sub. You'll see what I'm talking about, and it'll give you a reference point in setting up your system.

 

So what you are saying is to leave a gap? Let say cut the highs at 100, and the lows at 80? As an example. Never tried that before.

 

No, what I'm saying is that the overall sub volume should be lower with respect to the music. I know that a lot of people like to set their subs to high volumes, but that causes bass to get muddy and slow. To be accurate, subs should be sonically "invisible." It should sound like the bass is a natural extension of your speakers. The sub should never overpower your mains.

A great way of testing your bass is to play music that has a lot of detailed, consecutive bass notes. Bass guitars are great, as are r&b songs with nice bass lines, or even jazz cd's with lots of bass plucks. Some cd's I use are:

Counting Crows - "August and Everything After" (bass guitar lines)
Louis Armstrong "20th Cent. Millenium Collection" (bass plucks)
Wyclef Jean - "The Carnival" (Apocalypse is great for testing deep, deep bass)
YG Family - "Best of YG" (Korean music - great for testing bass... seriously, if you want, hit me up with a PM and I'll make you a sample mp3 of great bass lines from it)

When testing bass, you want to make sure that the transition from your main speakers to your sub is smooth (no hot notes, no holes, etc.) Easiest way to do this is to listen to just your main speakers (if you have a low-pass x-over point, leave it on) and listen to how the bass sounds. Then, add your sub and make sure it picks up where your mains left off. The sub should sound invisible normally, but it should fill the low end when those notes hit.

About the x-over point, it's hard to say where you should set it, without knowing what kind of equipment you have, what kind of crossover slopes you're using, etc. Try the extremes though. Set the x-over point high (100-120hz) and see if you like it compared to it at it's normal point. If you like what you hear, then try setting it halfway between and work from there. If you didn't like what you heard, try setting it in the opposite extreme (set the x-over point low 50-60hz). In general, setting a sub takes a long time and much experimentation. Just remember that usually, subs are set too loud. HTH

 

Most cars suffer from mid-bass boominess, which happens because the HP x-over on the mid-range and the LP x-over on the subs are set at the same frequency. Supposing x-overs are 2nd order 12db/oct, and the x-over was set at 100Hz, the mids are still producing 50Hz albeit 12db less, whereas the subs are producing 200Hz signals. If you draw the slopes and calculate the total area under the curve the area between 50Hz and 200Hz is a lot higher than the surrounding areas. Because this freq range is louder than the ranges below and above it most people compensate by boosting their sub levels (increasing the area under the curve on the sub side). Human ears are more sensitive to higher freqs so the mid-ranges aren't adjusted.

Let's say you're tuning your system. Best place to start is with all the spec sheets that come with the speakers, cross overs, amps, etc. Identify what the drivers are capable of reproducing accurately. Remember the info provided is based on the manufacturer, and since all cars are different the information should be taken with a grain of salt. Basic cross over points are 80Hz for subs, 150Hz for mids. Get a test CD and listen for similar "loudness" across the 20Hz-300Hz range. If there is an area that sounds louder than the others adjust the cross overs accordingly. Tuning takes a lot of time. You can do the job quick and easy with your ears and a test CD. Or you can actually sit down, test your equipment with oscilloscopes, RTA/SPL meters, and a graphing calculator then listen, then do more math, etc.

Yes, I turned a simple question into an extremely complex one.

 

Sounds good. The only thing I would caution is using the manufacturer's spec sheets. First of all, because the cabin of the car and the placement of the speakers has a huge effect on the frequency range, especially in the bass and mids. For instance, a teg sedan has a huge boost in the 60hz range (like 6db) and a drop in the 400hz range. That's the cabin's effect. With regard to speaker placement, if you don't use separates and only have full-range speakers mounted in the lower front door panels, you'll also have a large roll-off in frequencies above 10khz, because of how low the speakers are positioned wrt your ears (treble radiates in a much narrower pattern than bass).

Also, it's true that if you set a sub's x-over at 80hz, it'll still lend to the 150hz frequency range, but you gotta remember where the sub is placed. If it's in your trunk, it might be true that it's pumping those notes (100-200hz), but when listening from the cabin of your car, it won't reflect the levels you might expect, simply because deep bass travels better than the bass in the 100-200hz range.

Redblues hit the nail on the head though - if you want to go hard-core, you can use spl meters and measure the frequency response, but it's entirely possible to do it by ear too. Oh yeah, another thing to remember is that when the car is moving, road noise and wind noise tend to mask the bass a bit, so you might need to turn up the bass a little when driving, as opposed to when sitting still.