My experience with the Alpine CDA-9853.. Priceless..
I picked one up as part of a package deal, otherwise, I would have never considered one. You can pick one up preowned for $150 on Ebay.
This HU is priceless for anyone that is looking to get serious about sound Quality (CDA-9853 0r 9855 or anything that has the same processing with built in delays, adjustable crossover points and SLOPES as well as the capability of user settings for tweeter and rear channels that double as midbass (bandpassable, allows you to run rear channels as dedicated midbass)
What this allows you to do is throw away your passive crossovers, an introduction to a fully active system with incrementally adjustable delays, all this optimizes imaging and midbass response when used properly. Once you get involved with all this, you will never use passive crossovers again, you will also wonder where all that extra midbass is coming from. You will also be blown away by the fact that your vocals sound like they are coming from the HU in the center of the dash..
My introduction into a fully active system happened by accident. I came across this deck, learned how to use it, went from a 3 way active to 4 way active by adding an additional 2 way active XO to the front outputs.
This allowed me to run subs from 23HZ (subsonic in the active 2 way XO set to 24HZ, this helped because I put a pair of 12W7s in a huge sealed enclosure that almost acts like a ported enclosure, 6 CF gives no airbrake to help control cone movement, so the 24HZ cutoff really helped) then I set the HU crossover to 70HZ with a 24DB slope (smooth flat response with no peaks or muddiness, just clean tight slamming bass..) 2-JL Audio 12W7s with over 3000 watts rms to them.
Then it allowed me to run the rear outputs to a 2 channel amp powering 4) 6.5" midbass drivers with 300 watts rms per side from 50HZ (24 DB slope) to 200HZ (18 DB slope) with 1.2 MS delay (which made the midbass slam)
Then I was able to run the front outs from 200HZ to the active crossover which I used to split the signal between the midrange and tweeter, allowing me to set delays for perfect vocal imaging. Out from the crossover to a 4 channel Mmats amp, 160 watts x 4 rms.
Once tuned, the end result was a system that for the first time, was more of a pure SQ system than something just loud and aweful.
For the first time,
A) I had midbass that slammed so hard, I didn't need the subs for most music.
B) I also had centered vocals, sounds like the singer is in the middle of my dash.
C) First time I owned a system where everything blends so well, you can't tell where the speakers are, there is a wide, tall, deep soundstage, almost like wearing headphones, definitely sounds as good as my home stereo and I spent a lot of money there..
When you close your eyes, you can't tell where any of the speakers are, you can't pick out the tweeters or mids, can't tell the subs are coming from the rear, the first time I owned a true SQ system. Also loud as hell and clean as hell, minimal EQ, everything sounded incredible with drivers that were not super expensive.
You can also get away with using only decent amps, with the crossover points and slopes correctly set, delays properly set, you would not believe the difference in sound. I ran expensive amps, but it wouldn't have made a difference.
For speakers, I was running a cheap mix of Mmats tweeters and midrange with Polk Audio Eosone (home audio speakers, total of 4-8 ohm 6.5" mini subs from 2 way bookshelf speakers) Truth is, the only speakers worth anything in my entire system were the JL subs. My system cost less than 2K to build but it destroyed anything any of my friends had, they all paid to have their installs done, using top of the line JL gear, my system put them all to bed.. Not only did I have an unbelievable sound, I did it on a budget, and my soundstage and sound reminded me of a few trophy winning SQ systems that I have heard. I am finally there..
Drawbacks requires 6 channels of amplification for a true 3 way active system (5 if you use a Class D monoblock for subs, 7 to 8 if you decide to go true 4 way active which is what I did)
I did a 3 way front stage, no rear fill, had to mount the tweeters in a way that worked because I have no way of delaying them separately, that would require 8 channels of processing with 8 channels of separate delays, I had only 6 that I turned into 8, so the tweeters were delayed the same as the midrange, but with careful positioning, I was able to make them blend.
Now that I know about the importance of delays* and crossover slopes* (just as important as crossover points and EQing for fine tuning) I know the importance of active crossovers, I went and picked up the Clarion DRZ9255 for a HU, picked up all PPI Art Series amps, and I am now using all Hybrid Audio for my front stage, still using the JLs for subs, now powering them with a pair of PPI A1200.2s.
Alpine CDA-9853 or 9855 or any mid level Alpine deck (must have delays for every channel and band passable rear outs for dedicated midbass use)
For anyone entry level that is looking to get serious about a true SQ system that will image and possibly allow for competition or at the very least, will definitely improve your learning curve and sound these decks are a must..