time alignment

[cali yaris]

This isn't actually for the Yaris, but I figure you car audio guys can answer it.

On my tC, I have JBL 10"x2 subs, and JBL GTO series speakers throughout, with a Grand Touring amp powering it all. I have a Kenwood 7" HU if that helps.

The bass is "late" compared to the mids and highs, and it bothers me. I would like to move the bass forward or delay the mids/highs. Do I need more equipment, or can I do it with my current setup? Am I describing a phase problem?

thanks in advance, ask whatever questions you like, I'll try and answer them.

http://www.sciontcx.com/images/audio/finished/0317.jpg

[CTScott]

In the audio setup for your deck, does it have a "time correction" or "time alignment" configuration?

[cali yaris]

I don't think so. Just went through all the audio screens to make sure.

It's a Kenwood DNX7100

http://www.kenwoodusa.com/Car_Entertainment/2007_Car_Entertainment/DNX7100

[talnlnky]

I've never heard of anybody ever complain about the bass being late. Time alignment is generally used to adjust for the difference in the distance the left or right speaker is from your ears... Time alignment may help your problem... but i'd bet money that your issue has nothing to do with the distance it is away from your head, but rather the group delay of your setup which is primarily a function of your box design & the sub's Le (inductance of the coil).

Both are spendy ventures to test. New sub or new box. Looks like you are running a sealed box, so I doubt changing the box will make a big difference.

If you have bass boost turned on, turn it off and see if that helps. Huge spikes in frequency response tricks the brain into thinking that the sound is boomy which can often be seen as being slow and muddy.

[_S7V7N_]

Look for the Phase control, you may have it reversed on the Headunit, if not the amp may have this control also, I'll see if i can find some Operation Manuals. http://inform3.kenwoodusa.com/manuals/DNX7100.pdf


It does have a Reset Button to set it back to factory settings if it didn't sound like that before.

[rob323]

Time delay in the digital domain is the best way to adjust impulse response, but $$$$.
Phase is related to impulse response but if you only have a 0 and 180 degree switch, then it's not much help.

As mentioned before, group delay caused by badly design ported boxes are the usual culprit, sealed boxes are usually never a problem.

It can also be attributed to the type of amps used, configuration that the woofers are wired in, the impulse response of the woofer and the crossovers used.

Passive eq will also cause phase shifts and can play havoc with crossover points.

Below is a pic of a mate's impulse response, using phl mids and and 18" phl bass driver. Note the much slower impulse response of the bass driver compared to the mid and then the brilliant impulse response of the ribbon tweeter (this is a pair of active speakers for home that I helped him make).
http://i39.photobucket.com/albums/e154/rob323vr4/audio/time-aligment.jpg
And after correction:
http://i39.photobucket.com/albums/e154/rob323vr4/audio/time-aligment_corrected.jpg

But really, you need to find out what the problem is before taking steps to correct it. Whack a mic in you seat, load up REW or some other program and take measurements. It's easier than turboing a car!

[talnlnky]

Good call on the 180 phase switch (if that amp has one). If the amp doesn't have one, you can always do it manually by switching the polarity on the speaker wires to the subs. positive wire from amp goes to negative terminal on sub, and vice versa.