LaserSVT

As some of you here know I am somewhat of an audio nut and typically have a super high end setup in my cars. My trucks sound system is every bit of $30,000 and is pure sound bliss. Mosconi Zero amps, Illusion subs, AD woofers and mids, Japanese titanium ribbon tweeters, 11 speakers running fully active (no passive crossovers, no shared amp channels) each with their own 31 band EQ and own amplifier channel.
When I bought my Audi I wanted the B&O system. I would not buy one without. Reason why is I always go nuts with car systems and wanted this one to remain stock just with better bass. The B&O is by no means perfect but tuned right and with the right sub it is a clean, clear, accurate and well staged system. The detail and definition from 1000-20,000hz is FAR superior to the Bose counterpart.
That being said, what I have done here can be done with Bose or B&O but takes a little work. You can fit a 12" sub running infinite baffle by building up a 1.5" thick baffle board for it and hang it below the rear deck. The rear decks holes (which are nearly non existent) need to be sealed off and some sound dampening to the rear deck needs to be added. Resonix is the BEST sound damping material on the market by a large margin. Forget Black Hole, Dynamat etc etc, Resonix is what you want.
Next step is the amplifier. The B&O sound system has over 400 watts RMS to feed the stock sub which is more than 90% of the Line Output Convertors (LOC) can handle and we had set one on fire. The Bose system is half that power so any LOC can work BUT after trying several amplifiers I found the Audio Control LC 1.800 was the best option and for several reasons.
1; Its small
2: Its class D so power drain is minimal
3: Has the BEST on board LOC ever made (designed specific to add to OEM systems)
4: Has some tricks up its sleeve.
One of those tricks is it has a 24db subsonic filter. That filter allows you to push the sub HARD without hurting it. The other trick is how it "corrects" OEM issues like how ALL OEM systems will start to pull back bass and sub level the louder you turn it up. This amplifier has adjustments to find that spot when the OEM stereo turns bass back and will restore it to proper levels without distorting it. Also it has a "bass" **** which is just a remote level control for the sub. Mine is hidden inside the front cup holders power port and we glued the "12V" power cap to the **** so when you look at the cup holders you see nothing. You just turn the "12V" power cap to add/remove bass. This is handy because I like classic rock and some modern stuff so sometimes need a little more "kick". lol

Now there are a million ways you can add bass to these cars. Cut the whole deck, do a blow through, make a regular box etc etc. THIS way is the lightest way and keeps the entire trunk space available still.
I went through several high end subs. Stereo Integrity SQL 12, Illusion Audios C12XL, HAT Legatia and Clarus 12s and all sounded better than stock but each lacked a little something. The SQL was loud and punchy but didnt get deep deep. The HATs were very precise but were not loud nor did they dig deep. The Illusion went deep but it simply wasnt made for an IB setup.
That brought me to a company called Acoustic Elegance. They are bespoke subwoofers and made to your specs. This happens to be an AU12IB with the Apollo upgrade that allows it to play louder longer without heating up. I have been feeding this thing 800 watts RMS and it handles every bit without complaint. It is probably the second best sounding 12" subwoofer I have ever heard and the BEST IB sub I ever heard. Its attack and decay is simply stunning, low end extension will try to open my sunroof. The clarity and accuracy are amazing. It reproduces subsonic and even infrasonic frequencies with such ease that its reminds me of my 24" home theater subs.
It is not cheap but It is not expensive. Its not to shake the Earth. Its simply the best sounding sub you can add to your OEM system and really bring it to life. I think I paid $475 for it. Remember though, install is PARAMOUNT! Best speakers in the world will sound like trash if installed poorly.
I have included pictures of the first sub because that shows what the baffle board looks like but the smaller magnet sub is the one I would suggest to anyone that likes their D4s system, just wants more and better bass.

Striker2237

Very nice, I am happy with the stock system for the most part and if I want more I have access to a reference grade floorstanding system. What's in the mini fuel cell you have back there? Meth?

LaserSVT

Yeah its a meth tank. And whats "reference" grade? Or I guess I mean to ask what speakers/amps is the floor standing?
Like for instance, my old system by which I measure all others to was my old Infinity IRS-V with the 12-12" servo subs having their own amp built in and a Carver Silver 7 (the 90s one) driving the remaining 96 drivers. I miss those, hated selling them and will never be able to obtain another set.
My current home system is more theater based so its Klipsch RF7-IIIs and SVS SB4000 subs (waiting on the SI 24" enclosures to be made) and while perfect for movies the Klipsch are too "shouty" to be a reference standard.
So now my reference system is in my truck. But that has 400lbs of CLD, CCF and MLV (much like you would treat a room for critical listening) with all main drivers on axis to my ear and digitally time aligned. The door speakers play to 50hz where the subs take over and play to 4hz. Amplifiers are Italian made/designed and run pure class A to apx 20 watts and run the remaining 3000 or so A/B. The truck is VERY close to the IRS sound signature with the upper midrange being its weak point (cones vs ribbons). BUT I am running the same tweeters as the IRSV just with Italian mid/mid bass drivers. It JUST got the amp change from these wonderful SI amps to the Mosconis and removal of the Audiofrog 12s in favor of the Illusion C12XLs and that deck is currently being pulled to add the new one with hi res audio (Tial player via .... whatever the newest high res connection is) and better streaming music ability with Android Auto vs BT
If I were able to build a home music room again I would buy the PS Audio towers and amps as those sound just like the IRSV only with less distortion and more output and are only 60k vs 500k.
Audio nut, into it for 40 years so am always interested in what people like.

But this is a taste of my "refrence" setup:

Striker2237

Quad McIntosh 501s in vertical amp config, Audio Research pre-amp, stand alone balanced circuit with power conditioning, full balanced system, high end cables etc etc......speakers are VR5s https://positive-feedback.com/Issue4...nniversary.htm

It's a ruinous system. Makes everything else sound like it is missing so much by comparison. However all in the setup is nearing $80k so....it's able to form such a perfect soundstage you can hear things in the floor, ceiling, and behind you easily with insane spatial recreation and depth. It's possible to tell the shape and size of the recording room and if there is a pop filter screen or not and where the door is to the recording room etc. It really distorts what one expects from a system

LaserSVT

Oh a man after my own heart! I LOVE Mcintosh! Had many over the years. They just have a sound to them.... yeah yeah all amps are supposed to be transparent but Macs....mmmm goood stuff! Also I have heard OF that speaker just not it... well all of it. The 3 people I know that heard them (1 owner) said they are pure ear candy. I used to run the ScanSpeak R2904 (your tweeter) in one of my systems and even wrote a review for them that was published in one magazine and is on DIYMA. I also have a pair of SEAS Excel 9" sitting on a shelf I pulled from my.... well forget which car. So I am familiar with the drivers in that tower and they are all quite special. Kudos sir, you have a damn fine ear and expectation of "proper" sound then.
You would be a person that would like the AE over the factory sub. Its invisible and does not "sound" like its behind you. BUT unlike my truck or your reference system its more like a great pair of headphones. In my truck I can hear Stevie Nicks singing in front of Mick and hear Lindsey clearly to the left with Christy McVee beside him singing backup which alwyas pissed me off because the keyboard is CLEARLY coming from the right so thats where the backup vocals should be at. I hate it when a studio does that. But I love hearing the singer take a step back and breath in or that little twitch of a pick right before it strikes the chord. I want that high hat to sizzle and snap! I want that kick drum to sound like one, not a reproduction of one. I want to close my eyes and point to where each instruments at.

Love my Macs!

Striker2237

Awesome to hear you know exactly what I am talking about! I agree with you completely, the B&O system indeed strikes me as sounding like a good pair of headphones but the base is a tad inaccurate/slow and sometimes has a strange response to certain higher frequency base tones. It's not enough to anger me or anything like that but in my mind "for a car system" it is excellent and I really can't complain, it is good enough that there actually is some "real" soundstage and imaging going on. You have an incredible system, one of the best I have ever seen in a car and those IRS-Vs are insane. My dream full size towers are undecided personally, I need to listen to more options before I pick one to strive toward but for now I am focused on cars.

I mostly bought the W12 for how it drives but after being disappointed with the Bose system in my 4.0 I wanted the B&O as one of my 3 deal breaker items......I was PISSED when it showed up with a blown sub I had to repair. I was extremely close to following your other threads on how to uprate the sub but ultimately decided to give the stock unit a chance since I need all the trunk space I can get for when I go to out of state shooting matches.