Sound system installation done, how do I tune it?

usurp · 02-01-2008, 12:35 PM

I finished installing my sound system today but I don't think its sounding its best at the moment.

my setup:

Alpine iDA-X001 Head Unit
Boston Acoustics SX55 speakers front and back (50w)
Alpine V-Power MRP-F250 Amp (4x40w)
Infinity BassLink II (10" sub, 250w amp built in)

Currently I have good highs and good low but zero midrange. Also with the subwoofer off the 4 speakers sound pretty ****.

How do I go around tuning my setup?

**SirGCal** · 02-01-2008, 12:56 PM

Well;

1) did you polyfill behind the speakers? If not; get a bag from walmart (like a whopping $4) or a sewing shop. Stuff a huge handful of it in there so the rear of the speaker is completely covered. That will help.

2) If you had something out of polarity; it would be the other way around. Bass (without the sub) would be really weak and it would sound hollow. If that's what you have without your sub; one of your speakers are out of phase. To easily check. Fade and balance the system full to once side (like just the front/left speaker). If that speaker alone sounds a lot better; one or more of the others are out of phase. (That means the - and + wires are reversed).

3) Once these are figured out; be sure to set the gain on the amp properly. With that amp, those speakers, you're looking for ~ 12.65Vrms on the output channels. http://www.sirgcal.com/audio/input.html

From there you could try the basslink intentionally out of phase (there is a switch on it for 180 deg phase shift. to see if that changes/helps at all. Double-check your crossover settings, make sure the basslink is set to low-pass (don't think it's capable otherwise) and make sure the amp is set to high-pass. Probably ~ 120Hz to start with.

Now once all of that is done; then the tuning can begin.

You balance the front/rear via the amp (turn the rear sensitivity down to balance properly with the front; IF you want to... Street rigs often leave this set to the amp's set level from the meter test (you can go down from there; just not up)). You can (if able) tweak phase, time delay, etc within the system. This often means additional controls or one heck of a head unit to let you tweak this far. But for street rigs; as long as you do the above stuff; you're usually fine.

usurp · 02-02-2008, 03:15 PM

SirGal I used a lot of pollyfill today and it improved sound and removed all rattles. (for a while atleast the rattle on the right hand side came back).

anyway i am really not liking how the sub is sounding. All the reviews online said the bass was tight but mine doesn't sound tight, my old bazooka sounded MUCH tighter. Thinking about it now I am guessing it might be because of the crossover, I have it set at like 100khz i think. But I remember even when I dropped it down to 50khz it never hit a bass note tight. It just seems to keep booming. Do you have a clue what I a missing or is this how its supposed to sound?

thanks dude

**SirGCal** · 02-02-2008, 03:19 PM

Do you have bass or something turned up signifigantly on the head unit?

usurp · 02-02-2008, 03:43 PM

no, bass and treble are on neutral but i do have the subwoofer volume which i increase and decrease. this tuning is thing is pretty frustrating.
i am going to try something tomorrow.

currently i have the subwoofer out in the headunit going to the subwoofer. tomorrow i will try connecting the rca cables of the front speaker to the subwoofer and see if that changes anything.

**SirGCal** · 02-02-2008, 06:58 PM

If you're using the RCA outs specific for the sub; then that's the best option. Front/rear RCAs would probably sound much worse. But make sure you are on the right ones.

Also; check the head unit's sub settings to see what's up there. Is there a bass enhancement or sub level control? Very possible; To start, turn any enhancement off and set the sub control to the middle to see how that works. My guess is the sub control is either nearly off or maxed out causing clipping or just a lack of enough output to the sub.