I have spent some time with Jagur XFBowers& Wilkins systems- MK1and MK2and MK3(MK2 is quite rareproducedonlyhalf year or so) I have alsodissasembled front and back doors trims to see upgrades posibility.

I have founded only few minor flaws on BowersWilkins systems in XF –
1)too thin door with no bracings and thinplastic trim leads to vibrations
2)some tonality impabance at 160Hz (bump) hz and 1-2kHhz (dip)khzrespectively

Apart from that itsvery good stock audio system. One of the best I have heard. Anyone who critcsthis systems should try achive better withfew usd drivers.The only things Iwould change is to let front tweeters play lower(to project soundstage and focuseven more higher and improve midrange texture)

Now some technical things

• SUBWOOFER- Mk1 have foam surround,Mk2 have rubber surrounds. otherwise identical.

2)MIDWOOFERS - MK1 version havevery nice bass units. voice coil is 30mm ,and normal ferrite magnet, with quite lowCMS/high Fs- compression occurs earlier than overexcursion and bass itself isquite tight(spoiled only by vibrations of doors)
MK2have same bass units, and later MK3 have black kevlar cones but small neodymium magnets –same as Meridansystems . BL issmaller , voice coil is smaler andsound is less powerfull and goes to compression already at20W. its downgrade IMHOI think fromdrivers perspective midwoofers is highest quality comparing to other drivers.

3)MIDRANGES MK1 1 have steel basket, small VC and pastics duscap. MK2 have biggervoice coil, bigger neo magnet ,pressed paper dustap and plastics basket.this is where I have some critcs.MK1 midrange have more peaky top end and I easilycan hear nasty cone break up. MK2 is moresmooth sounding(bigger coil=more inductance, bigger mass= less top octave)butits have basket frame resonanses and I would say those even morepronouncedin level than MK1.in MK1 postprossesing is aplied whenincreasing center channel- frequencies from 5khz is tilted up. probably its to compensatedirectivity.

4) Center channel-MK1 uses same midrange unit, MK2 uses Coxialunits with tweeter aded (see tweeters section)

5) Rear shelfMK1 uses same midrange unit, MK2 uses Coxialunits with tweeter

6) Tweeters .there is hughe technical diferencies in tweeters – Mk1 have more thandouble higher resonnase frequency, much smaller magnet.they sound diferent as well, MK2 tweeterssound more lush and more powerfull- they can be corssed as low as 2khz whilemk1 3.5khz or higher.in rear doorsthis is esential when tweeters work harder

because coxial unit in dash mk2 have morespaciuos and 3D soundstage comapring to mk1.

amplifers is very diferent in conctruction,mk1 uses Toshiba 4 channels chips , mk2 is compelteyl diferent( with loadresistors). actually power declarationof 440 B&W syuseis quite realistics each channle 44wats attolerable THD.1200W numbers took from the sky (or probbaly added tweeters/coxials and increased midranges voicecoil)

if anyone is interesting more deeper I can provide more details..measurements.
Ihave decidednot to modify bowers sytemas it very cleverly made( changing 2ohms drivers to 4 will require more powerfull amps)and decided installall new speaker system in my xf .

I measured spaces and its inceribly perfectfor instaling big drivers depth I to glass is whooping 95mmand I will fit hughe 7 inch midwooferswith 6 x more power handling(4 layers voice coil, magnet size is 122mm, of course all doors will be bitumen coveredand pastics strengtened because evenstock midwoofers ratles door. I install all new midranges which I wil built custom formyself needs from scan speak and focal parts.I will also instal hughe 35mmfront tweeters with 420Hz Fs and moove midrange to high xover from4khz to 1khz. which make system soundvery audiophile.will use MK2 rear shelf which I grint to accept 130mmmidwoofers and in corner of grill 20mm dedicated titanium tweeters. rear dorrs will have 3 inch lower tweeterupper mid crossed to 500hz with midwoofers. idealy I would wantcoxial but not sure if fit(one member toldthat fit here coxial)

I will feed all this with new installed power ampwhich I will feed from linear outputs of oem amp(was quite a task to find linear input to chip in 3 layer pcb)

I abandoned second shelf with free air subsidea as new 4 psc 7 inch powerfull wooferswillhave way more bass than stock subs. but I willhave remoovable 85liter 2x 13 inch focal utopia 33WX subs with extra amps with real800W (4000W) amps for the fun.

 

I have also upgraded IAM head unit an mk1 amp(see pics) with Nichicon KZ, panasonic FC and muse bipolars, also shunted with MKP caps, changed few voltage regs to better ones after upgrae not so much space left.

 

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Good explanations. And I do like my upgrade (Upgraded speakers in the doors and upgraded the amp and subwoofer. Have not done the center surround, yet or rear deck speakers. Programmed the head unit to support surround.

Questions:
The rear parcel shelf, do you know if the 2009-2011 shelf is the same for 2012? Are the 2014 shelf's with meridian the same fit and speakers are they coaxials? I'm looking to put in the parcel shelf with speakers but don't want to buy them for my 2012 if they are not going to fit.

 

Also, can you define MK1, MK2 and MK3? what years?

 

Parcel shelf interchangeable on all x250 but you CANT use facelift model mk2 shelf to MK1 system even if the plugs go straiht in, polarities is reversed. it was surprise for me. all rears and centers is coxials from facelift model. I have bought meridan black poly coxials for testing and how they comepre to mk2 yellow kevlar units. hope this helps.