I am not an expert on car audio so I need some recommendations from the gurus around here. My current setup is an Alpine CDA-9857 deck driving into an Apline MRV-F450 5-channel amp, powering a set of Boston Acoustics RC-620 front component speakers, originally powering a set of Boston NX-67 speakers in the rear stock location, and one (1) JL 10W7 sub from the 5th channel. I believe the power rating of the amp is 4 channels x 50 Watts each + 1 channel at 200 Watts (for the sub).

I am pleased with the RC-620 components in the front and the 10W7 sub is 'ok'. I don't want to mess with changing the sub because it is shoehorned into one of Nazars enclosures in the compoartment behind the passenger seat. A little more dynamat and eliminating the rattle in the flip-down compartment door should make the sub sound pretty tight. Also keep in mind that when I first had the system installed, the installer neglected to run the RCA from the head unit to the amp's sub channel input, so I had no line level control for the subwoofer output. All I could do was adjust treble, bass and master volume from the headunit. It actually sounded OK so I didn't have a lot of motivation to correct the problem.

My problem is that my rear speakers (the NX-67's) are blown. It's not totally noticeable with really abrasive heavy music because there is so much distortion anyway, but try listening to anything jazz or piano or mid-range oriented and it's game over. So one day a few weeks back I took the headunit and center console apart and ran the RCA for the subwoofer level control from the HU to the amp input. I also disconnected the rear speakers from the amp (but did not disconnect those RCA's from the headunit) because I was sick of listening to the constant buzzing. The blown speakers are still installed but not plugged in.

So now my setup is Headunit to amp powering only the front components and one subwoofer. I know some people run this kind of setup (i.e. without rear speakers) because they aren't really necessary to set the sound stage in a small car like the Z. However I feel that it just isn't cutting it right now. The sound is pretty unbalanced and the bass seems totally disconnected from the rest of the sound. It may be that the component speakers I have up front are not intended to work on their own to produce balanced output, I dunno. My gut feeling is that I need speakers in the rear just to fill in that weird void between the music in front and bass in back, and hopefully help the subwoofer blend in better with the rest of the system.

My question is: if what I said above makes any sense, can you guys recommend some relatively inexpensive speakers that would be compatible with the other audio components already in place, that would produce decent sound and be fairly reliable? I would like to spend $100 or less, which will obviously limit my choices but should allow recommendations like Infinity, Blaupunkt, Pioneer, etc.

All opinions are welcomed...I need an education on this stuff!

EDIT - Also does anyone have experience using component speakers for the rears in the Z? Might be a fun project mounting the tweeters somewhere, although I wouldn't do it if it doesn't really benefit the sound of the system. Thoughts please!

 

OK, a couple things to touch on.....

1) perhaps the sub doesn't blend with the front components due to Xover settings? What are you crossing over at for the sub and the components? I would start out around 80Hz and go from there. Basic rule of thumb both crossover points (high pass and low pass) should be set at the same frequency.

2) If you insist on using rears, I would stick with Bostons for the rear fill, just a simple set of coaxials (S, SX or SL line), so that the timbre is matched to your front components. Since they sit right behind your head, you will still hear them no matter how low you fade them.

3) Since you say the 10w7 sub is just "OK" sounding, here are a couple questions..... The 10w7 wants an enclosure with 1.00-1.375 cu ft sealed; is that enclosure big enough for the 10w7 sub? if not, you can use some polyfill to make the sub think it's in a larger enclosure. Depending how off the enclosure volume is, you can use 1/2 to 1 Lb. of polyfill. Also, 200 watts is below the recommended minimum stated by JL Audio (says 250 is the minimum rms power). You could be starvng it for air space as well as power. I know the 10w7 is an awesome sub, but perhaps for your application and location another sub might make all the difference in the world.

 

Thanks for all that input.

1) I will have to check that out...I'm not sure how to adjust that stuff (I'm guessing it's on the amp somewhere) but I will try to figure it out.

2) That's interesting about the timbre of the speaker....I guess I always figured a speaker is a speaker but it is sort of a musical instrument so that makes sense.

3) What are the symptoms of under-powering a subwoofer? Can that damage the sub? Maybe I should look into buying a stand-alone 250W or higher amp for the sub. Regarding the enclosure volume, I will have to find out from Nazar at Wicked C.A.S. Here is a link to the picture of the sub on his website:

http://www.wickedcas.com/gallery/mai..._2705.JPG.html

It's a fiberglass enclosure, with wall thickness at probably less than 1/4 inch. Supposedly it was designed with the 10W7 in mind, so I presume the interior volume is within the recommended limits. I'll try to find out these details and post them up here.

Thanks again!

 

Sage advice.

And I'll add what caused the rear speakers to blow in the first place? You'll need to address that source cause that this will be the last set of speakers that you install.

I agree on the wrong size box. Ideally he needs gain set-ups on the system and a proper size box for the woofer or new woofer for the box. As long as the amplifier isn't driven into clipping your not going to hurt the woofer's sound but a wrong size box is the number one reason why good woofers sound bad.

 

1) Yes, you should have xover settings on the amp as well as in the headunit settings (I think that Alpine has them). You should commit to using only ONE of these options.

3) I'm not as worried about you putting 200 watts into a 250 watt minimum sub as I am the volume. I had emailed Nazar about the volume of that enclosure a few times and never got a response, so I went with an under strut box instead. Like I said, That w7 wants around 1 cu ft after displacement of the sub (which is 0.09 cu ft) Polyfill slows down the waves so the subwoofer 'thinks' it's in a larger enclosure. You can line the entire inside of that enclosure with about 2-3" of polyfill (should be about 1 Lb.) and that could help things out a lot.

 

OK I'll check the settings int he HU and on the amp after work today.

Just to be clear, underpowering a speaker will not damage it, correct? I'm not completely up to speed on electronics. Intuition tells me that less power = less damage, but I also know there are lots of equations relating current to inductance to power to voltage to resistance, etc., and I want to make sure that I won't cause any damage. Will underpowering a speaker make it sound muddy, or just limit the dB level?

This might be a good chance to get more familiar with the low-end of my sound system. I had everything 'professionally' installed so I haven't experienced things first-hand. Maybe this weekend I will take out the sub box and try to estimate the interior space, to see if it falls within JL's specs. If not then maybe it is time to find a different sub that accommodates the box (even though that's a bit ***-backwards). I just don't want to put a sub box in the hatch area if I can avoid it.

 

Post back your xover settings when you get them and we can work on that to see if we can blend things better for you.

Underpowering a sub in itself is not detrimental to a sub's well-being. However, the problem comes in when you are underpowering a sub, you usually crank the gains and volume to get the performance you desire out of it, which can cause clipping and distortion and THAT can damage the sub. Like I said, 200 watts is not too far under the minimum recommmended rms power, but it could be playing a small factor in why you aren't getting that "wow" factor out of your sub.

Try using water to figure out the volume of the enclosure if you can. 1 Gallon (US) = 0.13368 Cubic Ft. Use an empty gallon jug and pour one full gallon jug into the enclosure at a time until it is full.....count the number of gallon jugs to fill the enclosure and then multiply that by 0.13368 to get the cubic feet.

 

Thats for all the educated input guys. I'll check the crossover frequency settings on the HU and amp this afternoon, and we'll see about tearing into the sub enclosure over the weekend.

 

any updates?