Audi B9 A4/S4 B&O door speakers

Audi B9 A4/S4 B&O door speakers

Bobby Kinstle

Project Category:
Car Audio

Project Level:

Project Time:
20+ Hours

Project Cost:
$500 – $1,000

Project Description:
Despite having quite a large number of drivers and equal amounts of hype, I found the Bang and Olufsen system in my new Audi quite disappointing. Since most of the drivers are poor quality separates and many are odd sizes and some are 8 ohm, very little from the car audio world can be used. I replaced the 4×6″ 8 ohm horn loaded woofers and 4″ mids in the front doors, and the 6.5″ woofers in the rear doors. The rear door tweeters were just fine so I left them alone. The front pillar tweeters are rolled off at 10KHz inside the amp so replacing them won’t yield much benefit. The factory 10″ rear deck subwoofer was terrible and it can easily be replaced by most free air 10″ DVC 4ohm subwoofers. In the end I also added a Pioneer GM-D8701 amp to drive the sub tucked under the spare tire. The factory amp drove the sub just fine but I needed to reduce the low pass filter point to 45Hz.

Before starting the project I measured each driver in car the best I found with a Dayton Omnimic. To isolate the drivers, I put the microphone through the hole in the base of a clay flowerpot lined with foam on the inside and then wrapping a towel around the outside. Even then total isolation was pretty difficult on a couple of drivers, but I was able to get a useful view into the frequency range of each driver. One side note was the front door 4×6 woofers which are actually driven to 43Hz but can’t play anything below 58Hz. I only noticed because the 50Hz test tone on the Dayton test CD made that speaker vibrate.

Design Goals:
My design goals were to correct the harsh midranges, poor vocals, abysmal deep octaves on string instruments, and weak sloppy bass.

Driver Selection:
Front door woofers: 296-412 “Aurum Cantus AC-180F1 7″ Woofer”

Front door midranges: 264-1484 “Peerless by Tymphany GBS-115N25AL01-04 4-1/2″ Aluminum Dome Woofer 4 Ohm”

Rear door woofers: 299-609 “6-1/2″ Poly Cone Midbass Woofer 4 Ohm”

Subwoofer: Kicker CompC10 DVC 4Ohm

Enclosure Design:
I mounted the new drivers into the factory locations, so no enclosure design was needed. However the front door woofers required significant work which seems to fit in this section. The original speakers were rear facing into a horn that directed the sound towards the inside of the vehicle. After removing the drivers, I cut the top surface flat so I could mount a normal round driver onto it while utilizing the factory screw mounts and wiring harness connector.

The front door woofer also had only a 4×6″ opening in the grille, even though the fake grille marks are 8″ in diameter. I opened the closed holes above the new woofer so it wouldn’t be too restricted, but would still be strong enough to deflect any foot that bumped the door there when people were getting in and out.

Front door midranges bolted up to the factory location with spacers and some gasket material around the edges.

Rear door woofers bolted up with a standard Audi 5.25″/6.5″ speaker adapter ring.

Crossover Design:
I used the built in crossover points from the factory amplifier.

Tips & Tricks:
I strongly encourage reading my spreadsheet with my test data before starting down this project:

Add sound dampening material inside the panels while you are in there.

Sound quality was massively improved. Bass guitar, cello, the bottom quarter of the piano all sound great. I had to lower the subwoofer crossover point because the Arum Cantus woofers played so well down the the factory cutoff of 43Hz that they were creating a strong overlap band from 43-70Hz. I should have made my life much easier if I had used a 6.5″ woofer rather than the 7″ as the woofer I chose required extensive cutting and grinding inside the door panel.

The peerless 4″ dome midrange is the real star of this show. The sound quality is simply unbelievable. The dome shape creates incredible off axis response that fills the entire front seat area with perfectly imaged sound FAR better than the fake 3D effect the car has build in. (I disabled all the 3D effect features that I could in software). The peerless midrange is bright and authoritative but NEVER harsh and brings out details in the music so tiny that you probably didn’t even know where there. For example, if I played “The Wind that Shakes the Barley” by Dead Can Dance, on the factory speakers you hear a woman singing punctuated by painful passages. On the peerless midrange, you hear the echos off the walls and instantly recognize it as a large church and her voice is always smooth and pleasing, even when she really raises the volume. I don’t think this driver gets near the love that it deserves.

The standard $6 6’5″ rear door woofer continues to be a crowd pleaser and meshes perfectly in the rear door with the rest of the system. Don’t be scared of the price. There’s a reason why you keep seeing this woofer in so many projects. I always keep a pair on hand in case I need another set and Part Express finally runs out of them.

Some day I may revisit this project to replace some of the surround speakers that can’t fully be turned off like the rear deck 4″ full range and the center channel 4″ woofer and 1″ tweeter. It’s low priority since these speakers don’t contribute that much to the overall project.

About the Designer:
I grew up in the Mojave Desert in a small community of scientists, craftsmen, and engineers. We were the kind of people who didn’t accept “it’s impossible” or “you can’t do that”. If I want something that doesn’t exist, I’ll just make one. Now I’m a thermal engineer in the computer industry and I currently hold six US patents.

Project Parts List:

Dayton Audio OmniMic V2 Acoustic Measurement System
Aurum Cantus AC-180F1 7″ Woofer
Peerless by Tymphany GBS-115N25AL01-04 4-1/2″ Aluminum Dome Woofer 4 Ohm
6-1/2″ Poly Cone Midbass Woofer 4 Ohm

Also Included:

Subwoofer: Kicker Comp C10
Subwoofer 3/4″ MDF mounting spacer
Rear door Metra 6.5″ adapter rings for VW/Audi


Add yours
  1. 1
    Ricardo Scott

    This seems to be the most honestly written opinion of their system. I applaud you and I have a can-do attitude towards everything car audio-based!!

  2. 2
    Help Me

    Out of curiosity what would be preventing someone from using the Aurum Cantus AC-165 Carbon Fiber/Kevlar Woofers instead? The only difference I saw is a slightly lower RMS handling and then higher frequency capability. The 1 in. voice coil over the 2″ would be beneficial too to having a more crisp sound in the bass as well.

    • 3
      Bobby Kinstle

      The Aurum Cantus AC-165 power handling is a little low for this position and could be damaged if you really blast it at full volume. Other than that it’s probably a better fit as the 7″ driver I used was too large and I had to extensively modify the inside of the door panel to make it fit properly. If I were to do this again I’d stick to 6.5″ drivers max.

  3. 4

    Anyone know the sizes of the rear mid-bass speaker in the rear of the Coupe – or is it the same as the one in the 4 door???

    • 5
      Bobby Kinstle

      Yes it’s the same 4″ speaker as in the front door. Same goes for the center channel speaker as well. The dash corner mids used for 3D effect are smaller.

  4. 6

    Did you require a LOC to install the subwoofer amp? I have read they are required on B8 Audis with B&O, I did not need one on my B8 Audi without B&O. I now have a B9 with B&O and plan to move my amp and sub over from the old car. Thanks!

  5. 7
    David Mortensen

    Hi Bob, first thank you for all the work you have put into the testing and fitting for the speakers. If you were to install the recommended 6.5″ driver for the front door woofer, what speaker (with brand and part number) would you use in your system instead of the 7″ that you used to avoid all the work on the speaker grill? I have the 2019 Audi RS5 Sportback with the B&O System and will closely follow your information guide and your lead on this outstanding (and much needed) sound system upgrade.

  6. 8

    Hey Bob, what did you use to mount the 3/4″ MDF ring to the rear deck for the 10″ subwoofer? Any info would be great! Thanks!

  7. 9

    I got a bad b9 front subwoofer. Any ideas where I can source a 4×6” speaker that will fit the oem acoustic assembly? It seems I would need a 8ohm 100 w speaker

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