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Old 14th December 2007, 11:21 PM   #21
Flyin11 is offline Flyin11  United States
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Join Date: Sep 2007
Car: 2003 Honda Civic EX Coupe
RCA cables: Rockford Fosgate brand
No external processors or crossovers
Headunit: KDC-MP4028 with 4V preouts using RCA inputs
Power and ground wire: About 8 foot of 8 gauge power wire with a 40 or 60amp fuse between the battery and amp and the ground wire is only about a foot and a half and grounded to the seat bolt.
Remote wire: 14 gauge
Speaker wire: 14 gauge
Amp: Alpine MRP-M450 (220 X 1 4ohm - 400 X 1 2ohm) - under the seat
Subwoofers: 2 12" JL Audio 12W1v2-4 wired in parallel for a 2ohm load and connections to wire screw terminals from the outside are soldered on the inside
Front Speakers: Kenwood 6 1/2's (Not sure on model) - connections soldered on
Rear Speakers: Kicker 6X9's (Not sure on model) - connections are regular speaker connectors
Car stock tweeters on the doors
Sealed 3/4 MDF dual 12" sub box - Standard front firing rectangular box in the trunk pointing away from the seats, towards the back of the trunk. Model# H-212 (adjusted inside to make 1.27 cu ft per chamber)

http://www.subzoneusa.com/dual_hatch.htm
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Old 15th December 2007, 12:53 AM   #22
Clipped is offline Clipped  Thailand
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point the box forward and push it all the way to the back.

unbolt the back seat and tilt the top forward about 6 inches.

did you hook it up yourself? sometimes shops hook up subs at a lighter load and leave a voice coil or two disconnected so the system is less stressed and you so you wont come back with a warranty claim.

check the gains yet? sub level? crossover?

if your battery is dimming with 400 watts, that is a problem...

1.run another ground from batt to chassis
2.run ground wire from engine to transmission to chassis.
3.run another wire from alt positive to batt positive.
4.run another wire from alt casing to engine block to chassis.
(if its mounted in rubber)

if you have a multimeter check your voltage before starting the car, with the leads still in place check the voltage when starting the car...then keep the leads hooked up and see what the voltage drops to after the alt heats up...if the leads are long enough drive around playing music and see what the voltage drops to.

check water level in battery, drive around on the highway and just drive and let the battery charge up without turning the system on....i know its tempting to turn it on while driving but please refrain.
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Old 15th December 2007, 01:03 AM   #23
jol50 is offline jol50  United States
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If you run it hard on something with low bass, are the subs hitting xmax? It looks like that amp should put them there. If not I'd say the 8ga could be on the small side, but that is a short car too. What you could do is hook a meter to the + and - of the amp, then run it hard and see what kind of drop you get. If your ground is bad it will show as well as lack of 12v. Normal to drop some, but if you get under 12 it might have a problem. If there is a bad connection and the amp works, you have to check under load to see how low the current is. I run 420rms on 4 infinity 300wrms subs so it is no surprise mine doesn't get to xmax, but they are IB and say half wattage for that. Still 105 under ideal conditions to 150 is a ways apart. But you are 200 each, even 175 should max them out according to JL. They might not xmax in sealed box before they burn up, but still they should be moving a lot. Looks like that rating is for ported too, they should move more in a ported box, would likely hit xmax at rated max power.

Clipped has some good points also.
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Old 15th December 2007, 03:54 AM   #24
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There is only two things that would all in all solve a dimming problem, that is 1 a dedicated isolated battery system ( not connected to cars elec system) or 2 a battery isolator and a second battery. Even if you had a 300A alt the time it takes for the regulator to notice the drain would cause a 1-2V dip in voltage providing the strobe effect. A stock alt arround 100A with a good battery on music is good for a true 1000rms, this has been proven. Caps are not useless, they just need to be used in conjunction with a good charging system and battery (s). A good non carbon cap with a low ESR can help mask the latency problem of an alternators regulator but cannot take the place of real honest to goodness voltage... Polo.
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Old 15th December 2007, 05:33 AM   #25
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Location: Doerun, GA
Quote:
About 8 foot of 8 gauge power wire with a 40 or 60amp fuse between the battery and amp and the ground wire is only about a foot and a half and grounded to the seat bolt.
A 400W amp should be grounded to clean metal chassis, not a seat bolt.

Tim
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Old 15th December 2007, 07:26 PM   #26
shagone is offline shagone  United States
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Quote:
Originally posted by tsmith1315


A 400W amp should be grounded to clean metal chassis, not a seat bolt.

Tim

i second that! i was going to point that out but i figured that was a given and that he might have scraped the paint away under the seat bolt at the mounting point. a bare metal spot on the chassis is a much better choice even if you have to use your own hardware. i always sand down and clean my grounding points well befor making the connection.

you could also try 12awg ofc wire on the subs. is the wiring inside the box 14awg or smaller?

what are all your crossover settings (frequencies and slopes)?
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Old 15th December 2007, 11:06 PM   #27
Flyin11 is offline Flyin11  United States
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I adjusted some of my settings on the amp...A little bit more gain, a little bit more bass, and I moved the frequency up a little bit on the low pass on the amp and now it sounds pretty dern good. I still defiantly think a new HU with the higher voltage preouts is going to make a huge difference like it did before as well. I'm also eyeing maybe a amplifier change as well...Might have my eye on a JL Audio amp to compliment my subs. I talked to a audio dealer today and yes, they are a Rockford Fosgate dealer so of course he was trying to sell me a Rockford amp and telling me a lot about them but I still can't find a 07 model that gives me the specs I want and need to make me get a Rockford. He had a lot of interesting things to say about Alpine amps and I could agree on some points. He also agreed with me on what I told him about my experiences with Alpine decks so we were also on the same page there. I will try the grounding point change and scrape away paint and all but that's not really going to increase the power...just maybe give it a little cleaner sound which is not what I'm going for. I also saw people on this baord saying they ground their amps to seat bolts and rear seat bolts, also to rear common grounds from the factory electrical system and have been fine. I will try though...

The wire inside the box to the speakers is the same as the wire outside to the amp...14awg I believe. I saw a topic on this board before about you not needing huge or big wire for your speakers...any wire size will do...So I don't think that needs to be changed and I'm not taking the speakers out the box again and take a chance on the screws not screwing tight on the subs for a good sealed fit.

Crossover frequencies:

High Pass: HU is through
Low Pass: HU is 80hz and amp is almost at 100hz...I get more bass out of the amp that way.

No settings for slopes as there is nothing on the HU or amp for that...
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Old 16th December 2007, 02:02 AM   #28
jol50 is offline jol50  United States
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It depends, mine is on a seat bolt but the bolt is quite large say like a 3/8 bolt. I took the paint off under it, and it is higher than the floor so any moisture should not be a problem. It is also right next to the trunk where my amp is, about where the bottom of a rear flip down seatback would be.
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Old 16th December 2007, 07:13 PM   #29
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Quote:
I will try the grounding point change and scrape away paint and all but that's not really going to increase the power...just maybe give it a little cleaner sound which is not what I'm going for.
Try looking at it this way:

Ohm's law governs anything electrical. V=I x R.

Let's say the painted surface, bolt threads, spot welds, etc add up to just 0.1 ohms of resistance.

The voltage lost when the amp is trying to pass 20A through that ground connection is:

V= 20 x 0.1 = 2 volts

2 volts is significant, and can certainly take the edge off of dynamics. It can cause the amp to overheat.
If the amp is really running near full output, and not just delivering big transients, power will absolutely suffer.

That's not to say this is the problem in your situation, but little things add up. And the more current you're dealing with, the more important the little things become.

The same applies to connections on the power wire at the amp, fuseholder, and battery terminal.

In addition similar problems in the battery/charging system are often the cause of dimming headlights and other nusiance electrical problems.
The 4 connections Clipped mentioned are critical, and if there's just 0.1 ohm of resistance in any one of them, there will be considerably less voltage to run the car's electrical system.

Tim
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Old 16th December 2007, 07:57 PM   #30
shagone is offline shagone  United States
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Join Date: Apr 2007
Quote:
Originally posted by Flyin11
I adjusted some of my settings on the amp...A little bit more gain, a little bit more bass, and I moved the frequency up a little bit on the low pass on the amp and now it sounds pretty dern good. I still defiantly think a new HU with the higher voltage preouts is going to make a huge difference like it did before as well. I'm also eyeing maybe a amplifier change as well...Might have my eye on a JL Audio amp to compliment my subs. I talked to a audio dealer today and yes, they are a Rockford Fosgate dealer so of course he was trying to sell me a Rockford amp and telling me a lot about them but I still can't find a 07 model that gives me the specs I want and need to make me get a Rockford. He had a lot of interesting things to say about Alpine amps and I could agree on some points. He also agreed with me on what I told him about my experiences with Alpine decks so we were also on the same page there. I will try the grounding point change and scrape away paint and all but that's not really going to increase the power...just maybe give it a little cleaner sound which is not what I'm going for. I also saw people on this baord saying they ground their amps to seat bolts and rear seat bolts, also to rear common grounds from the factory electrical system and have been fine. I will try though...

The wire inside the box to the speakers is the same as the wire outside to the amp...14awg I believe. I saw a topic on this board before about you not needing huge or big wire for your speakers...any wire size will do...So I don't think that needs to be changed and I'm not taking the speakers out the box again and take a chance on the screws not screwing tight on the subs for a good sealed fit.

Crossover frequencies:

High Pass: HU is through
Low Pass: HU is 80hz and amp is almost at 100hz...I get more bass out of the amp that way.

No settings for slopes as there is nothing on the HU or amp for that...
have you tried using only one crossover at a time? the combined slopes may be too steep or of different slopes creating phasing issues? i like a slope around 70-80hz 12 or 24 db's per octave but thats just me and every install sounds different. also have you tried reversing the phase of your subs? some head units have this option. if yours doesn't you could simply reverse the speaker wires going to your amp or box (+ to - instead of + to + ect..) and see if the sound blends in better with the front stage. sometimes it works sometimes it won't.
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