freq's

[WTD2]

when i listen to some songs in my house stereo i hear a diff level of bass than the infinity kappa subs in my Yukon. Do i need to get some extra woofers for the higher end bass, or is there some type of adjustment i can do?

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[B_Master_Flash 10+ year member]

Higher bass frequencies? If that is what you are looking to achieve, look at your amp and see if it has a "bass boost" or something like that, its usualy either a knob, button, or switch, and turn it off. Then play with your gain until its loud again, and see if you like it. The "bass boost", or what ever it is called on your amp, makes the amplifier emphasize lower frequencies, so with it off, you will hear more of the higher bass frequencies (>60hz). I can save you some time right now and tell you it will sound like ass.

Oh, while you're at it, check your crossover. If it is too low, higher frequencies will be cut off by your amp. It should be set at around 100hz (play with it unitl its just low enough that you cant hear voices over the subs)

 

[Jim Boom 10+ year member]

Your house stereos woofers are probably taking the full range of frequencies of your music, when the subs in your car are only taking the lower end like below 60 or 50 hz mostly.

 

[helotaxi 5,000+ posts]

The acoustics of many cars creates a frequency "suckout" right around 150hz. This is right in the middle of the frequency range you are having problems with most likely. This is caused by a combination of destructive interference from a standing wave node in the car and usually by phase cancellation between the sub(s) and the midrange speakers as they are both playing at this frequency. Remeber that your crossover is not a straight cutoff. The frequency that you select is where the halfpower point for that channel is (-3dB from flat). The sub is still playing above that freq but it is being attenuated more and more, the farther above the freq it gets. This sound can still play hell with you frequency response if it is badly out of phase with the mids. Try swapping the + and - wires on your subs and see if it helps. You can also experiment with switching the phasing on one of your mids to see if that helps. If you have a HU that does time alignment, that can help this problem a lot, too.

 

[Mobile 10+ year member]

The acoustics of many cars creates a frequency "suckout" right around 150hz. This is right in the middle of the frequency range you are having problems with most likely. This is caused by a combination of destructive interference from a standing wave node in the car and usually by phase cancellation between the sub(s) and the midrange speakers as they are both playing at this frequency. Remeber that your crossover is not a straight cutoff. The frequency that you select is where the halfpower point for that channel is (-3dB from flat). The sub is still playing above that freq but it is being attenuated more and more, the farther above the freq it gets. This sound can still play hell with you frequency response if it is badly out of phase with the mids. Try swapping the + and - wires on your subs and see if it helps. You can also experiment with switching the phasing on one of your mids to see if that helps. If you have a HU that does time alignment, that can help this problem a lot, too.

Just to clerify though, your crossover slope will increase the cut-off rate. Isn't a 24db slope pretty much a dead stop at the desired frequency?

 

[helotaxi 5,000+ posts]

Close, but it still has a slope. It will be 24dB down at twice the crossover frequency. Fourth order analog crossovers create phasing problem all their own also. There is a bit of phase lag created in the crossover that can play hell with the coherency of the midbass/bass transition. You are usually better off using a 12dB/oct slope and setting it lower and using relative phase adjustments to smooth the response than trying to go with a really steep slope.

Digital crossovers are a different story. Alpine, Sony and Pioneer have all made true digital crossovers in the past with slopes as steep as 72dB/oct. All processing was done before the D/A convertor and there were no crossover phase issues because of that.

 

[Jim Boom 10+ year member]

**** helotaxi, how many years did you go to school on this stuff?

 

[helotaxi 5,000+ posts]

I'm a military pilot with a degree in Econ. My car audio knowlege is all self taught. I read a lot and tend to remeber it all. I also tend to grasp HOW stuff works, not just THAT it works. Just the way my brain works.

There are very extensive and technical sites on the web on crossover design and theory, amp design and theory, acoustics and speaker and enclosure design and many other topics. The only real challenge is having enough basic knowlege to be able to tell if the authors of these sites have a clue about what they are talking about and then the technical background to understand them when they do //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif By and large audio is a mature and well understood field. Tons of information is out there in the public domain you just have to go look for it.

 

[kickerlivinloud 10+ year member]

Were would one find some of these sites. I am very intrested....

Jon

 

[helotaxi 5,000+ posts]

http://www.google.com

http://www.altavista.com

etc...

That's how I find what I need.

 

[B_Master_Flash 10+ year member]

http://www.bcae1.com

http://www.loudspeakers101.com

good sites