Advice on setting up my system, crossovers, etc.

I wanted to get your opinion on the initial setup of my system... I've had 90% of my system for a few years now, but I'm upgrading the head unit so I'll have the opportunity to dial things in a good bit more. Here's what I've got: New HU: Alpine CDE-W265BT Amp: Alpine PDX-V9 Front Components: JBL MS-62C Rear Coaxials: JBL GTO629 Subwoofers: 2 JBL GTO804s Front and rear 6.5" drivers are in the doors (front tweeters are in the stock location at the bottom of the pillars). The two 8" subs are under the driver's side rear seat. My current head unit is a JVC KD-A735BT with limited EQ capability. The new Alpine should provide much more tweakability... particularly with the Alpine TuneIt app to tune the head unit's EQ, Time Alignment, and Crossovers from my iPhone. As far as my current tune goes, it sounds fine, but nothing spectacular. It gets a little boomy / honky on some bass guitar notes, and I even hear a little phase / comb filtering issues on some tracks. The JVC doesn't have any Time Alignment capabilities and only 3-band EQ, so I was kinda stuck. The Alpine HU has 9-band EQ, Time Alignment, and Front / Rear / Sub Crossovers with 6-24dB slopes. Not outboard DSP stuff, but should be enough for me. There are also crossovers on the amp. My questions: 1. Where would you suggest I begin on my crossovers? My first inclination was to set both HPFs (front and rear) to 80Hz at a 24dB slope and the LPF (subs) also to 80Hz at a 24dB slope. Thoughts? I know I'll need to play with it, but just want to have a good starting point. 2. My amp also has HPFs (12dB) and LPFs (24dB) built-in. Should I only use one or the other (head unit OR sub)? If I use both, am I doubling the slope? If so and I should only use one, should I use the HU's or the amp's crossovers? Does the fact that the amp only supports 12dB for the HPFs affect your decision? 3. My amp also has a subsonic filter for the sub that goes from 0-30Hz at a 24dB slope. I think I'd certainly want to take advantage of this filter on the amp at the very least. My 8" subs are rated down to 30Hz. My thought is to set the subsonic filter at 30Hz and call it a day. Agree? 4. Related to EQ, I remember reading back in the day that you should only CUT frequencies, not BOOST frequencies (i.e. build the curve you want by cutting certain frequencies to achieve your curve rather that boosting some and cutting others, and then increase your volume to compensate if needed). If I remember correctly, the thought process was to not introduce any extra noise into the system. Is this thought legit? Should I try to only cut rather than boost and cut? Any other thoughts or tips for me while I'm at it? I hope to have the new Alpine HU in this weekend... Thanks! Drew

Building on my original post, is my thought process right on these two scenarios related to a perceived boost due to overlapping frequencies between the mids and subs? I read where about -30dB is where a boost becomes imperceptible. Is that right? If so, PerceivedBoost below is showing how much above -30dB these overlap induced boosts are... Scenario 1: Both the HPF and LPF are at 80Hz with 24dB slopes Freq (Hz)...Mids...Subs...PerceivedBoost 640..............0.......-96..........+0 320..............0.......-48..........+0 160..............0.......-24..........+6 80...............-3........-3.........+24 40..............-24........0..........+6 20..............-48........0..........+0 10..............-96........0..........+0 Scenario 2: HPF at 80Hz and LPF at 63Hz, both with 24dB slopes Freq (Hz)...Mids...Freq (Hz)...Subs...PerceivedBoost (@71.5Hz) 640..............0.........504..........-96......................N/A      320..............0.........252..........-48......................N/A      160..............0.........126..........-24......................N/A      80..............-3..........63............-3.....................+21.7 40.............-24.........32.............0........................N/A 20.............-48.........16.............0........................N/A      10.............-96..........8..............0........................N/A

1. Good starting point 2. Disable 3. Only use if the subs are in a ported enclosure. If sealed, disable 4. In general this is correct.Support the12volt.com