View Full Version : Bass adjuster

11-17-2008, 11:53 AM
A preface, I'm a newbie to car audio, but, very curious about it. I've been trying to improve the midbass on my front drivers. I'm in the beginning processes of sound deadening the doors and set my hipass to around 80hz, based on the advice of this forum. Besides that, I want to know how the bass setting on the HU works. What exactly is going on when I increase the bass setting? As I understand, most mid range speakers can't handle the lower frequencies, so by increasing the bass on my HU, it is only "amplifying" the frequencies that I set the hipass for the drivers right? So, in other words, I can jack up the bass and it should technically not damage my drivers since it's only handling a frequency range I set for it?

Can anyone confirm what I'm saying or clarify on it?

11-17-2008, 01:45 PM
When you set crossivers realize they aren't a brick wall. What happens is the sound below the high pass or the sound above the low pass begins to attenuate at a certain rate so the speakers are still playing frequencies above or below the filter, they're just gradually getting quieter as you get further from the crossover point until you can't hear them anymore. Even with the steepest slope this is true, this just means the frequencies are attenuated the fastest so you won't get TOO far from your crossover point before the driver isn't playing those frequencies anymore. If you set your EQ bass boost for more bass at say 60 HZ and your HPF is set at 80, no, you're not increasing the bass as much above your filter as you are below it but you are probably still boosting some of it.

In general most people here will tell you any boost is a no-no if you have the right equipment and a good install. I run with 0 bass boost on the sub and speaker amps and zero treble and bass boost at the head unit and when I play a good recording I get enough of everything in the proper proportions. If Im looking for more of something I find the frequency that obscures what I want to hear and I cut it just a little bit. This is really what you should be shooting for, good enough equipment tuned right so that nothing is straining to the point of pre-mature failure. Good way to accomplish this is good enough speakers and subs to give you the sound you want, then give them a little more power than they need.

If you absolutely MUST boost, realize that boosting anything increases the strength of the signal to a speaker ALOT more than you may think, especially if you aren't sparing with it. It won't automatically kill a speaker if you do it right, but if you are like most people and go overboard with a couple settings all at once it can do it really easily. Most people on here dislike boost because everybody usually goes overboard with it it and hurts sound quality when certain frequencies are boosted unproportionately but if you care more about certain frequencies than others, do what you gotta do.

When I checked my sub amp voltage with no boost and with a little bit using a DMM it jumped by ALOT. If you must boost your bass level, the best place to do it is at the amp rather than the head unit. Don't go overboard and back off on the gain. This way the boosted signal is going only to your sub, which may be better able to handle it than your speakers. If the problem is a lack of up front midbass, work with your crossovers. I found for my system a 5 or 10 HZ overlap, with my front mids set at 70-75 HZ and my sub low passed around 80, works best to give me a decent, firm up-front 'kick' while keeping the sub frequencies low enough that I can't tell where they're coming from. Therefore, the 'attack' part of a bass note sounds like it comes directly from in front and I can't tell where the deeper notes that form the body and reverbration of the bass note are coming from from the driver's seat so it sounds like the whole bass beat is coming from in front.

You do have a sub of some kind right? Sometimes people say midbass because they misunderstand the term and they really mean they're trying to get regular 6.5 inch mids to play subwoofer frequencies. There is only so much you can do with typical 6 or 6.5 inch mid range drivers in a typical two way front setup, then you need to start talking about things like dedicate midbass drivers, or custom front sub installs. Some component or coaxial sets are known for strong midbass response, some are not. Look at what you have and what it's realistically capable and decide whether this is an issue that can be resolved through tuning and install or whether it is better resolved by equipment changes.

04 Dakota Quad CAb
Alpine CDA 9883
Eclipse SC 8362 front comps
Infinity Reference rear coaxials
Pioneer premier 10 shallowmount in custom box
Eclipse EA 4200 4 channel
Alpine MRP M500 sub amp
Deadened doors and rear cab wall