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Tweak 8th June 2004 03:33 AM

Audio Setup Help
Hi, I don't know anything when it comes to audio. What do i need to do to make what i have sound good. I have an ma audio amp, 2 12"alpines subs and a sony hu. Please help, my car sounds like junk. Here are the specs I found on the internet for em:

Alpine Type R Subs:

Sony CD Player:

MA Audio Amp Desciption:
HC2502 2 Channel High Current Amplifier
High current- low impedance stable- Bridgeable- Tri-mode capable
Low level input- Bypass line output for connecting multiple amplifiers to the same signal
Variable low pass filter 45 - 120Hz
Variable high pass filter 100 - 800Hz
Variable bass boost 0 - 18dB
Variable bass boost frequency 45 - 90Hz
Variable phase shift 0 - 180 degrees
Variable output level control
Thermal- short circuit- overload protection
V. U. meters
Cooling fan
Continuous power ratings @ 4 ohms 2 x 250w-@ 2 ohms 2 x 450w-@ 1 ohm 2 x 750w- @ .5 ohm 2 x 1250w Bridged-@ 4 ohms 1 x 900w-@ 2 ohms 1 x 1500w-@ 1 ohm 1 x 2500w
Dimensions 11-1/2 In. (W) x 2-1/2 In. (H) x 24-3/4 In. (L)
Thanks, Matt

pape 8th June 2004 11:53 AM

maybe some new speakers to go with the subs?
Or do the subs sound like crap?

Tweak 8th June 2004 05:03 PM

the stock speakers actually sound pretty good, i'ts the bass from the subs that sounds horrible.

pape 8th June 2004 05:16 PM

what kind of box are they in?
is it properly dimensioned?

maylar 8th June 2004 05:48 PM

How did you set the amp gain control? Does it sound better when you turn down the volume? Is the lowpass filter enabled, and what frequency is it set for?

Tweak 8th June 2004 09:55 PM

I'm not sure about the dimensions and stuff, but it is a sealed box.

Ya, it sounds better when the volume is low. Dunno about the rest of the stuff you said.

Here are some pics:

Tweak 8th June 2004 10:15 PM

It's not set at all, I keep tweeking with it to try to get a good sound, but i'm having no luck.

pape 9th June 2004 04:09 PM

The first thing you need to do is turn the bass boost and gain down. you are probably well into clipping with any sort of volume.
Not sure what the level range is or the output from your hu, but it probably shouldn't be more then half for the gain. And you can probably go a little less on the LPF. You are a bit over 80.

I would have the bass boost at 0 and then use the HU to control bass boost if you need more, assuming you are using a sub preout.

plus you have the amp running 180 out of phase, try turning that back to zero.

tsmith1315 10th June 2004 04:22 AM

Lots of wise questions and good advice.

But first, are you SURE all of the subs' voice coils are wired in phase with each other? If not, nothing good can follow. To check polarity:
1) disconnect the speaker leads from the amp
2) hold the + speaker lead against the + terminal of the battery
3) touch the - speaker lead against the - terminal of the battery, The speaker should move outward, then return to center.
If it moves backward, then the speaker leads are reversed.
If it doesn't really move, but seems to make a little noise, then the dual voice coils on that speaker are not wired (+) to (+) and (-) to (-)

I agree with Pape, start by turning down the gain and boost. Also:
-Be sure the filter switch is set to LP (can't see it in the pic)
-Be sure you have a solid ground connection to bare metal on the chassis.

To set the gain:

1) With the amp gain down, turn the head unit up until it you hear a little distortion, them back it off a touch.

2) Turn up the gain until the sub amp just begins to distort.

That's it.

Now set the LP filter. Use your typical listening music, turned up to medium volume. I start with the filter set to the highest frequency (what was that, 125Hz?)

1) close trunk, sit down and listen for a minute.
2) decrease frequency about turn, and repeat from (1)
At some point you should notice the system sounds cleaner, without losing bass output. That'll probably be about where you want it. It's really a matter of taste.

To set the Bass EQ, start with it set at 0 and adjust it up little by little just like the LP filter. Listen carefully after each adjustment. Be careful not to add to much boost, -the amp will distort, woofers will fry, fire and brimstone, etc. If you find yourself really cranking the boost up (like over halfway), you may need to back the gain down a little to compensate.

A far as the box goes, Alpine recommends 0.7 to 1.0 cubic feet, and your box looks close enough to that to not cause any major problems You may increase performance by changing the box somehow, but it doesn't *look* like that's any real problem.

If you'd like to post the dimensions of your box, someone here can give you more detailed advice on that.

Tweak 17th June 2004 05:21 PM

cool thanks, i'll try those tonight

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