sunrise089

Today I helped a friend install some new audio equipment in his car. I had posted a couple of questions here about purchasing decisions and the equipment and install seemed to come together nicely (though the KnuKonceptz's 8 gauge wiring kit came with 10 gauge ring and spade connectors necessitating a trip to radio shack) . Basically the setup is as follows:

#Sony lower-mid-range headunit (using RCA pre-outs at least)
# Kenwood mono amp (200x1 @ 4 ohms and 400x1 @ 2 ohms)
# JL audio Stealthbox
# JL w6 6ohm DVC sub. This sub was bought to match the sub that originally came in the stealthbox, it isn't the new model of w6, apparently the previous model (the one purchased) was needed because of mounting depth issues.
#8 gauge power and ground
#10 gauge wire from the amp to box
#14 gauge wire pre-installed in the stealthbox

The sub was wired in parallel to create a 3 ohm load. Though the amp doesn't implicitly state its rating at 3 ohms, since 3 ohms is midway between 2 and 4 ohms (200 and 400 watts respectively) I assume the w6 should be seeing 300 watts of power. Initially I set the gain on the amp to 2 volts (settings range from .2 to 5 volts), the Crossover to 120 hertz (random number, in the middle of the range, no idea what it should be), turned off the bass boost, and set all of the headunit settings to flat.

The bass wasn't very good. It was ok, not terrible, but certainly not that 300 watts should sound like, I at least think I know that much.

Seeing how my friend had just spent a decent amount of $$$ off partly my recommendations (though he was pretty constrained in his purchasing parameters, therefore the Kenwood amp) I began playing with settings trying to make the bass level more acceptable to him (friend isn't a bass freak, he listens to classical, adult contemporary, and oldies music, no rap, but still wanted to feel he had got his money's worth). Eventually my emotions got the better of my head and I raised the settings to: amp bass boost on (12 db), crossover lowered to 100 hertz (again, no idea if this is good), and gain WAY raised to .3 volts (I cannot imagine this was a good idea). At those settings the bass sounds good, though still not comparable to another friend's 2 12" MTX subs with 400 watts of power. Obviously the 2 12"s are far more surface area, but the power should be only 33% more, so I don't know how much louder they should be. All in all I'd say the bass is at a nice medium-high level in relation to the music at the above settings (probably a little overbalanced, but not if you want to enjoy the bass at all or savor the feel) and if you bump up the "low" EQ setting on the head unit the bass becomes fairly impressively loud, but it also sounds like there may be a bit of distortion (not sure, doesn't sound terrible and the car's rattles haven't been eliminated yet).

Ultimately my question is this: how much bass should I be expecting from this setup, and if the settings currently in use are potentially damaging to the sub or amp (as I suspect) what other factors may I have overlooked/incorrectly set that may have kept the install from sounding as good as it might.

Here are the 2 oddities in the existing audio install in this car that may be affecting things, as well as some ideas I have that you might wish to advise me on.

Oddity 1: Best Buy (installed the aftermarket coaxial speakers in the doors and hatch that are powered off the headunit) installed Bass Blockers on the full range speakers set at 200htz for the fronts (6.5") and 300 htz (4") for the back. Don't know if the obvious loss of midbass is affecting overall bass perception.

Oddity 2: The mono amp is receiving its signal from RCA cables that apparently are coming from the Rear Pre-out of the headunit. Although I didn't remove the headunit at all today (the RCA and turn-on cables were already run) moving the headunit's fader control completely eliminates the bass from the sub when moved all the way to "front", while when moved all the way to "back" bass is unaffected. I suppose the headunit simply doesn't have a sub pre-out.
_______________________________________________

Idea 1: The is a small amount of polyfill in the Stealthbox, perhaps I need more or less.

Idea 2: The crossover point really matters, and I need to set it a lot lower/a lot higher than I currently have it set.

Idea 3: The sub was somewhat questionably sealed in the stealthbox (didn't have rubber thing that I have used before, bought silicone sealant) and the screws holding the sub were sort of forced to work, so if there is an air leak it might be really important.

Idea 4: The crappy Sony headunit puts out very low pre-out voltage and having the gain turned all the way up to .3 (or even .2, the highest setting) isn't bad.

Idea 5: The RCAs are somewhat crappy, and somehow added noise that is being picked up somehow affecting bass.

Idea 6: The 14 gauge wire in the Stealthbox is causing power limitations.

Idea 7: Something else I'm not thinking of

Null Hypothesis: The Kenwood amp and/or the JL sub just aren't that powerful. Comparisons to 2 12" subs are irrelevant and I just shouldn't be expecting very much bass out of a 10" sub/rather low end amp.

Thank you all so much for reading this VERY long post. If you still have the energy or interest to post a response I'd be very grateful. Thanks.

darkknight1999

Ok let I'm going to take a stab at this even though I really need to hear it myself to help you tune it.

Your right in stating that the HU and the AMP being on the lower side will have a negitive effect but honestly it should still sound fairly good.

You shouldn't have to crank all the setting up to make it sound right. It sounds like you may have wired it wrong to me.

sunrise089

Ok, though obviously you cannot see the equipment yourself to verify anything, heres how I wired things: (I also remembered a few things I forgot to include in the original post)

Power (I think its ok): 8 gauge wire crimped into ring terminal, ring terminal attached to positive post of battery using OEM screw, power wire screwed into included fuse terminal. Power wire continues from other end of fuse along engine bay, through firewall and along left side of car to amp.

Ground(I think its ok): 8 gauge wire from amp less than 2 feet, under interior panel, wire crimped to ring terminal, screwed to metal in contact with frame.

Power/Ground connections to amp(questionable): Like I said, the wiring kit included the wrong size ring and spade connectors, so 2 ring connectors were purchased for the ends of the wires not touching the amp. Radio Shack was out of the 8 gauge spade connectors I wanted to use to connect the power/grounds to the amp, so we jury rigged a solution (maybe this is the problem???). We used the extra 10 gauge ring terminals included with the kit and used the crimping tool to bend the circular ring to a oval shape. Then we wedged the wire into the 10 gauge hole (I am confident that we got a clean insertion, even though it was tight the wire didn't bunch up and jam) and then attached the oval connector to the amp by unscrewing the terminal screws, placing the oval in place, and screwing the screws back down. They are held firmly in place, but maybe the bending hurt their power handling? Anyways, there definitely is enough connection to make the amp work.

Amp to sub (I think its ok): 10 gauge spade connectors crimpled to 10 gauge speaker wire attached through the Stealthbox's connectors, don't know what the type of connectors are called, they are the type that you unscrew, place the wire through a hole that is accessed by the unscrewing, then screw the terminals back down to hold the wire. The wiring is labeled negative and positive, so its unlikely (though I suppose not impossible) I crossed these wire.

RCA to amp (Probably ok): Just firmly pushed the RCAs into the imputs. There is an imput labeled "Left" and one labeled "Right", and the RCAs aren't labeled, so I just guessed, since it's a Mono amp I assume left and right being potentially reversed doesn't matter.

Turn on lead: It works, amp turns on

In box sub wiring black: Black (negative) 14 gauge wire from Stealthbox entry terminal to "-" terminal on Voice Coil 1 (the w6 has two Quick Disconnect points on each imput of each voice coil, for a grand total of 8 quick disconnect wiring points on the sub, I imagine this is to make it easier to wire in parallel). Quick Disconnect attached to other attaching point on "-" Voice Coil 1, quick disconnect crimped to 10 gauge wire, ran over back of sub, connected to quick disconnect "-" of Voice Coil 2.

In box sub wiring red: Red (positive) 14 gauge wire from Stealthbox entry terminal to "+" terminal on Voice Coil 2. Quick Disconnect attached to other attaching point on "+" Voice Coil 2, quick Disconnect crimped to 10 gauge wire, ran over back of sub, connected to quick disconnect "+" of Voice Coil 1.

One other perhaps overall problem that might be causing problems: In order to get most of the wiring to enter their respective connector, we twisted the ends of the wires to get a tighter fit. I don't know why this would hurt, but would the compression of the wire inherent in the twisting cause any problem?

Hope this is enough information to allow you to visualize any wiring problems I may be having. Thanks for your assistance darkknight1999.

darkknight1999

Well it sounds right.... but I would double check that the wiring is correct. You could also try swapping the RCA's double check their connections.

darkknight1999

Also I would pull the HU out to make sure they didn't use a line to RCA converter. If they did they may have screwed it up.

sunrise089

Thanks, I'll try both of these.

mas

It's hard to suggest xover settings without listening to your system but I think there is room for improvement here.

Try this:

Lower the sub's xover setting to 60 (or even 50) hz.

Reset the HU's setting to flat and adjust the gains again.

Next, gradually raise the xover setting and see if you like it better - not that 60 is bad, I personally xover my subs between 60-80 Hz.

As for the bass blockers, 200/300hz front/rear sound too hight to me, I'd try 120/150 or 150/200.

Good luck!

c13

I used to sell and install stereos. I actually have a lot of experience with the equipment you're using. Kenwood amps suck and you have an extremely inefficient sub. This is a bad combo. The amps work well on a budget but must be matched with an efficient sub to work optimally. You should try another amp with at least 500 watts of out put. Jl makes balanced amps that produce the same output no matter the impedance load. That deck is also going to be an issue because of low pre out voltage,(The lower the voltage the more you need to turn up the gain causing distortion). As far as crossover settings for a 12" sub around 80hz to 100hz is usually a good place to start. All it does is cut out the sound above the frequency you set.