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      10-20-2010, 10:35 PM   #9
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MudPhud's Avatar

Drives: E90 M3 ZCP,E70 X5,E46 330i ZSP
Join Date: Mar 2005
Location: Maryland

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I used the stock left carpet trim and plastic cover (not the 'taller' one that others have ordered to accommodate stacked amps). The JL Audio XD fits with headroom to spare. No heat issues or power outages thus far (but I don't play music extremely loud either). Ventilation should be no worse than with the OEM amp. I'll have to wait until next summer to see if very hot ambient temperatures have any effect (but I really don't think so).


I'm no audio expert, but these are my settings:

1. I have the same identical crossovers for the Front Left, Front Right, Rear Left, and Rear Right (even though some components are 4" midranges and some are 5.25"). I also happen to use the same settings at all 4 corners (for no other reason than simplicity and in case the 'pucks' got mixed up, it didn't matter). I originally had...
S1: A (3200 Hz midrange lo-pass)
S2: 3 (tweeter notch on)
S3: 4 (reference soft, 2 dB per octave high frequency drop off)
S4: -8 (tweeter polarity in phase)
S5: +7 (tweeter polarity in phase)

But when I installed a Rainbow SLC 210.25 NG midrange + tweeter component in one door and compared it to the OEM midrange + tweeter in the other door (albeit with the OEM amplifier with its modified signals feeding both front channels), the highs on the Rainbow seemed comparatively soft or muted. Plus, I perceived that I wasn't getting enough sound out of the 4" midrange, so I decided to change and go with...
S1: B (3800 Hz midrange lo-pass)
S2: 2 (tweeter notch off)
S3: 3 (middle optimum tweeter attenuation)
S4: -8 (tweeter polarity in phase)
S5: +7 (tweeter polarity in phase)

The highs are definitely loud now. Perhaps too much, since I have to turn the treble down (and the bass up). A middle of the road setting with...
S1: B
S2: 3
S3: 4
S4: -8
S5: +7
might be a better compromise. Since I've already Dynamat stuck everything in place and reinstalled all the panels, I probably won't be able to realistically adjust them anymore, but I'm certainly happy with the way it currently sounds.

2. For the JL Audio XD700/5, I have all the gain settings (Channels 1/2, 3/4, mono sub) at their lowest. Sounds strange, but when I specifically tried to adjust the input sensitivities with 1000 Hz and 50 Hz sine wave test tones at 0 dB reference levels, my voltmeter (Extech Pocket MultiMeter DM110 from Lowe's) would not register any voltage >1 out of any of the speaker outputs even when dialing up the gain. For 4 Ohm Rainbows, the target voltages were expected to be 17.4V for Channels 1/2 and 3/4. The voltage output for the 2 Ohm Earthquake SWS-8Xs (pair of 4 Ohms in parallel) should have been 26.8V, but again I couldn't get any value. I was probably doing something fundamentally wrong but rather than risk distortion with higher gain sensitivities, I just left them all at their lowest settings (all the way counter-clockwise). When connected, the XD700/5 and all 10 speakers were plenty loud and clear so I quit trying to troubleshoot it and accepted it as is.

As for the amp's crossover filters, I have the front SLC 210.25 NG (4"+1") hi-passed at 95 Hz, the rear SLC 230.25 NG (5.25"+1") hi-passed at 80 Hz, and the SWS-8X (8") lo-passed at 145 Hz. Nothing too scientific here, but it seems to work.

I'm probably in the very small minority, but I actually like hearing the rear channels. I have the fader favoring the rear by a few clicks, and I wanted more midbass from back there. If all I wanted was rear fill, I wouldn't have gone through the trouble of upsizing to 5.25". Rear coaxials would have also been simpler, but I thought to myself, heck, if I'm going to rip this car apart I might as well go full bore. Knowing that the rear deck could come out fully (as others had shown) was the key deciding factor in allowing this project to go forward.

3. I have very simple, basic tools. Ratchets of various sizes, along with metric sockets and torx bits are vitally important. Socket extenders help, too. Tools I actually bought for this project include Bojo trim panel tools, the multimeter, a propane torch (to melt solder to secure 4 AWG wire into the battery distribution box connector), and the 4.75" hole cutter (expensive but worth it ).

I grew up in Rockville but currently live in Salisbury. You're welcome to take a listen any time.
2011 BMW E90 M3 Le Mans Blue | Black/Sycamore | 6-speed | Competition
2011 BMW E70 X5 V8TT Titanium Silver | Black/Walnut | Sport
2002 BMW E46 330i Topaz Blue | Gray/Aluminum | 5-speed | Sport