skiracer

and I need some advice. Should I remove the two rear deck speakers and use the porting for the subwoofer, should I disconnect the rear speakers and leave them installed (passive radiators), or should I leave them as they came from the factory? I'm leaning towards removing them, but I haven't tried anything yet.

BTW, I'm installing a JL Audio 10" sub (10W6v2-D4) in a sealed (0.7 ft^3) cabinet, and using a MB Quart PAB 1200.1D Amp to drive it. The amp has a remote gain dial so that should assist in setup and adjustment.

TSHong

hi passed at 80hz so it sounds pretty good at moderately high levels. I don't think the trunk is air tight enough for rear speakers to work as a passive radiator.

I did remove the ski boot and leave the arm rest down so the opening acts as a port. It does make a difference for my set up.

With your components, it should sound good.

ohbw

<img src="http://pictureposter.audiworld.com/84266/thethree161.jpg">

Most often the ones who look this good don't sing so well anyway. And Phoebe Snow and Gladys Knight look awful in bikinis, so that's not a solution.

Sorry, Doug, just thought I should get your blood moving before you head into the trunk. You are very old and likely stiff and creaky in the morning.

I'd leave the speakers in the deck alone. I'm not sure if you have the ports next to them that you can see next to mine in the image below. My memory is that you (fancypants) guys with newer S8s have some kind of (little Lord Fauntleroy) integrated cover under the speakers. But no matter.

<img src="http://pictureposter.audiworld.com/84266/111.jpg">

Those rear deck speakers are capable of producing mids as well as lows, and will do more of that when you change the signal they're getting, which is part of this mod. Covering less dynamic range makes them better at covering the range to which they are assigned.

They don't <i>just</i> put two tweeters, a mid, and a bass driver into a speaker like this to make you feel like you got something for your child's college tuition money. The more girls there are in the chorus, the better each can focus on doing what she does best:

<img src="http://pictureposter.audiworld.com/84266/imgp3164.jpg">

And you don't need a lot of porting to the cabin. All you need is for air to be able to move <i>somewhere</i> so that the sub is not flexing against an airtight container. Bass is non-directional -- as long as it's happening somewhere near you, it doesn't need the clear path to your ear that a higher frequency sound does.

Those holes in my deck and the open ski pass door are all I need open in my car. (If you have the holes but they're covered, just port the cover.) I don't even leave the armrest down -- doesn't make a big difference in my car, though if you don't have those ports in the rear deck I have, it might in yours.

Good luck tuning up the bottom!

<img src="http://pictureposter.audiworld.com/84266/thethree211.jpg">

mpollan

regardless of armrest or ski sack or anything else. For giggles I pulled the fuse on the amp to remind me of my roots. The fuse is never coming out. Have fun and enjoy the toons. Brian, as always, thanks for the pics and prose.

Mark

PaulW

I can't believe how good it sounds...the armrest stays up.

Once you get it in, tune it down and drive it for a few days, you'll be surprised how much bass you have. At first you won't have that "wow" feeling.

ohbw

Robert Plant &amp; Alison Krauss's album "Raising Sand" (13 songs, 57 minutes) at varying kbps rates (all using VBR):

192 kbps: 80.6 mb
256 kbps: 107 mb
320 kbps: 131.6 mb

So, big but worthwhile jump in file size from 192 to 256. 256 &gt; 320 is less of a jump percentage-wise but (to my ear) worth the extra file size if you have the storage space. That makes it almost a third of the AIFF file size on the CD.

Plus, as storage cost goes down over time, it won't matter. With a large-ish drive in your computer and a 160Gb iPod, today's standard, you can store a huge amount of music at 320 kbps, and never have to go back and reburn it.

This? Girl in a tub. Nothing to do with anything. Beg your pardon.
<img src="http://pictureposter.audiworld.com/84266/asrio742.jpg">

mpollan

and afterwards burned at 320. At 256 I average right around 10mb per song. The sound works for me as I usually roll with the windows down butt should have had the forethought for home stereo apllications. Now where is that bubble bath?

Mark

Dan McBoost

... Bass is air pressure....

Pressure side of things:
When the sub moves out, it is creating a sound wave/pressure. If you do the math of how much air the sub can move (area x Xmas (look in the thiele-small parameters)) and figure out how much the rear speakers can displace.. they will not be able to move nearly the same. PLUS as the sub moves out, pushing the rear speakers out, they are moved outside of their normal range of operation, thus fighting the sub and not making the sound as smooth as they would normally even if they are in phase(most of the time they max out and do nothing but make nasty noises, go back and listen). If they are not in phase they are trying to move opposite of the sub... and who wins?).

Phase which is both electrical/mechanical and TIMING:

Electrical/mechanical:
the power coming from the amp(s) is in an analog wave of changing voltage swinging both positive and negative. Essentially like AC from your wall outlet, which is typically @ 60Hz. If you had a subwoofer that could handle the power (I have done this at the shop I worked at for 10 years haha), you can cut an extension cord and "plug" a sub into a wall and get a **** load of 60Hz bass! Tweeters are a very fast wave (~20,000Hz- ~2,000Hz), mids are in the middle and subs at at the slower wave form (which is why they pump so much air). There is always some over lap from a cross over (if even equipped) where they those different speakers try and produce the same wave. if they are "out of phase" the mids (most noticeable in the lower end of the sound spectrum) are moving "in" (sucking pressure) and the sub would be moving "out" (pushing pressure) thus creating a lack of midbass and strange empty sound.

Timing of phase:
Because sound is moving with relation to time passing, even if something is out of phase, by the time the sound gets to the speaker out of phase it may contribute to that same sound.

Phase can NEVER be 100% unless you have a time alignment unit (I own two of these in my supras, both with IASCA designed sound systems) where you can electrically match phase, and then delay a location so they all arrive as your ear at the same time.

This is all very complex, and gets very deep. I worked as a master installer for over 10 years and have designed very large sound systems for IASCA and dB Drag racing competitions. If you want to talk about this further email me your number and I will call you.

Now, what I did (a basic install) in my A8:

Removed the rear speakers (btw concerts/live shows do not have speakers behind you ) and removed the ski bag. I made the vented enclosure to fire the sub through the ski hole and the ports through the rear speaker locations. This did the most important thing in a car with a truck. Making ALL the subs energy go into the cabin and not get waisting it in the trunk. The enclosure is very tight to the rear seats and wheel well to help this. This is a very very efficient way to get bass into the A8. It is possible to have great bass without a huge driver and amp. Phase is also very easy to control since it is simplified with less speakers.

High end systems in the car audio world have small numbers of drivers because of all of the above.. unless they time align it

Again, any more questions, you can write here, but I would rather talk(SPEAK) about it... much faster.

Cheers, glad to help,

skiracer

Storage is so cheap these days it makes no sense to compress music files. Buy the CD and rip it to a music server with no compression. Then if you need to compress the file for your MP3 player, you can compress it right off of the music server. I have a 1.3 TB NAS hooked to my network and have over 7000 uncompressed music files in BOTH FLAC and .wav. FLAC gives me the tags I need for my jukebox software and the wav files give me an exact copy of the CD for backup purposes. IMHO, buying compressed music from I-tunes or any other source is a waste of money. There are a very few sources for uncompressed music on the web, but buying the CD is still the best bet if you like more than 1 or 2 songs on the album.

skiracer

to try and get the rear drivers in phase with the sub. I plan on turning the bass way down on the head unit (to let the other drivers have less dynamic range requirements placed on them and better handle the midrange frequencies, then using the gain on the sub amp to get the bass I need). I think I'll start out by leaving the rear speakers in and seeing if I can get any decent sound out of them with the sub running. If not, then I'll remove the the rears and see how that works. The nice thing about these changes is that they are easily reversible.