Tons of Tech Questions!

First off I have check out the site many times, first time post! :-)

I have owned 2 Alpine 10" Type-R 1041's and had them in a custom box in a standard cab truck, very pleased as they were ran by an Alpine 7894 head and JBL BP 600.1 mono amp.

I have now moved onto a 2002 Blazer Xtreme with 2 15" Type-R 1541's ran by an Alpine MRD-M1000 mono amp. All I have is the Bose 6 speaker/6 cd system (sold the 7894 as I went off to college last fall,bad move) so I have a Scosche line out box for signal from the rear speakers.

I will supply as much info as needed.

4 guage power wire 20 ft long, ground 4 ft long, amp 1000 watt class d mono, factory head unit (gm/delco)

1st ?: My subs cut out very prematurely, not even close to max excursion.(although the headlights dim a fair amount)  E-3 displays on amp defining "excessive current". Could this be due to the preout converter and the signal it is pushing out, maybe non standard 4 volts to the amp?

2nd? I had a 38"x18"x18" box 2" slot port in the middle,3/4 MDF, sounded ok, had few air leaks around subs but sounded ok, I just went to a sealed box,dual chamber 38"x17"x16"just a little smaller for more "hit" and in hopes that my SPL would be more consistant from 30-200Hz but to my dismay my box's SPL is greatest from 120-200, from 30-120 it is extremely quit and shaky.Is polyfill a quick answer or should i resort to ported, or do I just flat out need a bigger box?

3rd? so I have the 2 15's, I may be able to trade them in for 4 12's (Type R of course!), for response and more power, using roughly the same box vol. but i have been drooling for a type-x 12, months before their release, they look great but their DB rating is very low and at 1000 watts each, its pretty demanding on an amp. Like everyone I want power with minimal volume but I really into acoustics so i was a flat response from 30-200 for Sound Quality. Your help would be greatly appreciated. thanks Robert

1. Are your subs 2 or 4 ohm DVC?

2. A properly designed ported box should be louder ,at and above its tuning frequency, then a sealed box. You might need to rewire your subs to fix this so I need the answer to question 1 first.

3. If you want to play it even louder go with the 4 12's and at lower volumes you will get better SQ, because 15s arn't going to offer much SQ. A MRD-M1000 should be able to drive a Type X sub fine, dont worry about the DB rating. It dosn't dictate if a sub is louder then another.

First off, , E-3 means 1, your impedance is to low, or 2 your ground isn't good enough.   Since you say you have 2 swr-1541d, that means you can only wire them to 1 ohm, or 8 ohm, , that amp can only go to 2 ohm,  Im thinking thats your problem.  try wireing up 1 voice coil on each sub to the amp, , that will be a 2 ohm load, , see what happends.  If you can,. id bring them back and get 2 SWR-1521d.       As for changing to 12's, thats totally up to you, , if you listen to just rap then 15's is they way to go, , but if you listen to rock, it may be a good decision to go to 12's.

The box size seems good, , i hope you put a separator to make 2 separate chambers, lots of performance is lost if the same airspace is shared.

What LOC are you using?  Make sure you have one that is specific to the bose.  Normally, bose is pulled and torched with a flamethrower before tossed into the dumpster.

1.  Impedance too high, gain not set correctly.  Not due to input voltage.  Your subs may be wired wrong, and the gain may be too high on the amp.  Fix that problem before doing anything about number two. 

My subs are dual 4ohm and I have them wired in parallel so I am getting a 2 ohm load to the amp, but if I am correct this value is just an average, so at times the resistance changes?

I thought that 20 feet of 4 was way too long but thats the length from the battery to right behind the back seat. I looked at a chart and theoretically i needed 2, maybe even 0 guage wire.I think maybe another problem is I bought this 8 guage wire from this chinese flea market and I swear when I stripped this stuff it was like not even 10 guage of wire inside, nearly 50% or more rubber/plastic coating, I was mad and ran out of funds so I just went with it.

I am going for 75% SQ and 25% SPL, the blazer's hatch rattles much more than i thought it would, so I am not into loud so much as the quality, I was from 30-200Hz to be at the same db level as much as possible.

As far as musical preference I hit everything from Rock, Metal Rap, Hip Hop, Country, and quite often bass demos,techno and mixes.

I also wanted your guy's opinions on the Optima yellow top battery, my local mechanic can get a good deal on it and I wanted to know if it was worth the investment?

By the way "Alpine GUy" how is the 9835 working for you? that seems to be next in line for my purchasing.

I'll try to get a pick of the subs and amp when I get the chance. thanks a bunch, everyone is great here.......and no I am not excited to go back to school in a week!

Two dual 4 ohm subs cannot amount to a 2 ohm load.

https://www.sounddomain.com/shop/wooferwizard.pl?num_of_subs=2&impedance_of_subs=4ohm_dvc&x=103&y=13

ok I guess it's a 2 ohm load with just one dual 4. but still I believe that Alpine can go down to 1 ohm, the amp has an on board temp and it never gets too warm, not even close to hot.

I have no gain on the amp but on the little scosche pre out converter box if i set it higher that 25% up it cause the subs to "pop" and quit early, again, leaving the "E-3" display on my amplifier. I really need a new head unit, i just dont like that converter crap....

so i have a few options, wire in series, get another amp to get a 2 ohm load to each, or get rid of the 15's and get one 12" Tyoe-X dual 4-ohm....man choices.......

You can get away with wireing up 1 VC on each sub and paralell them to get a 2 ohm load, i have done it many times, and i have contacted alpine about it, its safe to do so. Whell, not as safe as splittin the power over the 2 VC's, but i have never ever had a problem.

That amp will definately not go to 1 ohm, 1.5 ohm is the most iv gotten one down to without it shutting down from over current.  At 1 ohm to much power is drawn through the amp and the amp says No, and shuts down.

Also about your question about the 9835, , i loved it, best deck iv ever had, , almost to complicated, , but after you take the 2 hours to set it up, its very easy to use.  I no longer have it, , i sold it to a customer who offered me $300 more than what i paid for it, so im back to factory deck, and a LOC.  Im kinda glad i sold it, , cuz my elctrical system went on the fritz, my ignition wires turn to negative when the ignition is off, i can't belive my truck hasn't melted yet.

I'll get a new one once i get this problem fixed.

This is what I pulled up from JL's Tutorial on their site:

A common misconception with regard to dual voice coil speakers is the assumption that nothing changes if you power only one of the voice coils. With only one coil hooked up, a dual voice coil speaker will suffer a loss in reference efficiency of about 3dB (only half the coil windings are being energized) as well as a significant shift in its Thiele/Small parameters. This renders any enclosure calculations inaccurate unless you remeasure the speakers parameters with only one coil hooked up. Failure to account for the different parameters of a dual voice coil speaker with only one coil powered can result in very poor performance.

I guess I will try the 4 ohm load, if it doesnt work out for me I may go about trying this one coil method.......

The RMS rating of a speaker indicates the maximum continuous power level that can be used safely.  Any RMS value up to the rating is OK to use.

Wire your system properly for 4 ohms, setup your amplifier and head unit properly, and then see what kind of sound you get before you start worrying about making more changes or modifications.