My 6 to 10 speaker upgrade

[veryverydarkblue]

Instead of going on holiday next week, I’m planning to use the time and money to upgrade the sound on my Z4 which has business nav (the ‘ugly’ stereo) and the basic 6 speaker setup. I’m hoping there are some easy gains to improve the soundstage, clarity, depth and undistorted volume whilst retaining a completely OEM look and functionality, and ability to restore to (mostly) stock. I’ll document my experience here as, if it works, may be the ideal route for those with a basic stereo who, like me, wish the first owner had ticked the upgrade option.

Current setup:
- Business Nav (No separate screen) with retro phone prep
- Basic Speakers (x6)
- Bluemusic adaptor in place of the CD changer

Plan:
- Business CD ‘downgrade’ (Nav and CD changer are redundant)
- Amplifier in OEM location next to the battery
- Subs in the OEM locations, sealed boxes, run off the amp from the front high level speaker outputs
- Front 3-ways in the OEM locations, run off the amp from the front high level speaker outputs
- Rear mids remain stock

Purchased so far:
- Used BMW Business CD - £69
- Focal Access 165A3 3-way component speakers - £179 (with some sound deadening)
- Custom 3D printed mid-range mounts
- Hertz HCP 4D 4 Channel digital amplifier - £244
- Vibe amplifier wiring kit - £20
- DCSk 25m 16AWG speaker cable - £15
- Head unit connection extender - £15
- Reckhorn D165 6.5” subwoofers - 2x£33
- OEM subwoofer grills and 7x7mm square captive nuts - €90 delivered from Germany
- Misc. items to seal and line the speaker enclosures - c.£30
- 1m2 Noico sound deadening - £20
- various wiring tools, connectors, loom tape, screws and bolts
- 12mm mdf sheet

Total spend c.£700 excluding the replacement head unit.

I’ve so far built the subwoofer mounting plates using a cardboard template, and painted with high gloss which conveniently, but unnecessarily, matches the dash.




I'm sure I'll be back to ask questions of those who've been down this route already. Thanks to ph001, Magicarcher, Z4C_er and others who've posted their experiences and provided much of the inspiration for this little project!

 

[Jembo]

My previous 3.0 had the carver amp & speakers behind the seat - it makes the standard setup in my Coupe look like amateur night, though the S54 soundtrack easily makes up for it

Good luck with the fitting

 

[ph001]

Great - keep us updated. Interested to know if you sealed the top ports up on the sub enclosure. Initially I left them open (as per stock subs) but it sounded dreadful!!! Fully sealing the enclosures was key.

 

[Spriteracer]

Whilst you are at it you might want to consider upgrading the Bluemusic dongle to the new one with Bluetooth phone comms incorporated (shows up as Bluespeak). I had Bluetooth phone prep on my car but quality was terrible on an iPhone 8 and it would not connect to newer phones, Samsung S10 for example.

Have just done mine and the phone quality is very good. Comes with a mike and reasonable length cable but I found I had to extend it to put the new mike next to the original BMW one behind the steering wheel. Cost was about 47 EUR from Christian Wittich.

 

[veryverydarkblue]

Thanks for the info ph001. I’ve got everything I need to fully seal but will test as I go. Longer term I may experiment with alternative front plates to squeeze some additional volume in. Did you ultimately end up using the Reckhorns?

Jembo, it’s fair to say it’s crossed my mind more that once that a vehicle upgrade might have been a better use of resources!

Spiriteracer, Yes, I looked at that option (but too late) as I could have used that wiring instead of the other connection extender (doh!). Can you use SIRI etc. Through the bluespeak? I don’t really like to be on the phone whilst driving anyway, but SIRI could swing it...

 

[Z4C_er]

Good luck in the upcoming days. Looks like you'll be a busy boy.
Can I ask why you got the head unit extender?
And what's first, the subs or the 3-ways and doors?

 

[Z4C_er]

Great - keep us updated. Interested to know if you sealed the top ports up on the sub enclosure. Initially I left them open (as per stock subs) but it sounded dreadful!!! Fully sealing the enclosures was key.

I mentioned these to Veryvery. Do you think there's any benefit in adding them to the sub mounting plates to get a bit more kick?
https://www.aliexpress.com/item/32572882477.html?aff_platform=link-c-tool&sk=_d7WAd7B&aff_trace_key=233ac4e7d9c949d3ac1091920bff04e5-1596872524040-04653-_d7WAd7B&terminal_id=e974785a521743789e8c4c55eeecbf16&tmLog=new_Detail&aff_request_id=233ac4e7d9c949d3ac1091920bff04e5-1596872524040-04653-_d7WAd7B
Here's a build using a small driver and passive radiator in a 3 litre box. 33Hz is pretty impressive...
https://soundblab.net/small-subwoofer-build-plays-down-to-33hz/

 

[ph001]

The thing with passive radiators is that the box volume and port length is absolutely critical, otherwise the radiator ends up being out of phase with the main driver and you basically get zero bass response!

 

[veryverydarkblue]

Good luck in the upcoming days. Looks like you'll be a busy boy.
Can I ask why you got the head unit extender?
And what's first, the subs or the 3-ways and doors?

Just didn’t want to cut the original wiring so will attach all the new speaker wiring to the connector.

Choices choices! Heart says subs, head says fronts!

 

[veryverydarkblue]

1.5 days in and I'm probably about where I expected to be. Amp, Subs, 3-ways all in. Sub enclosures still to seal up as they definitely don't add anything of value in vented form.

The good:
- The Focal 3-ways along with the Hertz amp and sound deadening have transformed the front sound. I didn't try them passive, however I imagine this would still be a worthwhile upgrade

The bad:
- I'm getting some high(ish) frequency white noise from the amp on the speaker level inputs, even when the car stereo is off, rising with amp gain. Mostly through tweeters. I'm going to try separating the 'in' and 'out' speaker connections to the amp as they currently run together through the car from the front to the back. May also try a lower gain (currently set around 40%). Any other ideas?
- My 12v remote trigger for the amp, taken from white cable to the aerial booster, doesn't switch it on. Multi-meter is out of batteries. Auto-switch on from the speaker inputs works but I'd rather use the direct trigger. Hoping it's just a bad connection.

The ugly:
- Plastic is sharp, metal is sharp, cables are sharp. Buy shares in plaster manufacturers
- I had 30m of speaker cable including that which came with the amp wiring kit. It wasn't enough and for 'first fit' extra cabling is essential. My home hifi speakers are now closer together...
- The 5 metal clips along the top of the door cards are a real pain but will eventually pop if you pull/ lever hard enough
- Many dremel bits were destroyed expanding the tweeter hole to fit the Focals (take the grill out first)

 

[ph001]

Any audible noise on the speakers is usually a ground loop problem (basically your amp 0v and your head unit 0v aren’t exactly the same).

You could try fitting a ground loop isolator to the amp signal inputs, the difficulty is that they tend to rca in / out.

Where are you getting the power connection for your amp from?

 

[Z4C_er]

I'm not sure where you've placed your amp, but as 'ph001' queried, where is the power and ground coming from? When I mounted the active sub, my power was direct to battery (about a metre of cable), and the ground is into the bulkhead right next to it with about 10cm of cable.

I ran the remote wire back to the head unit and tapped into the adapter harness which should be the blue cable. How are you running wires back and forth? Is it though the centre console (with items removed)?

 

[veryverydarkblue]

Thanks both

Amp is next to the battery and wired directly to both terminals with short chunky cable (and in-line fuse)

Speaker wire pairs (‘in’ and ‘out’) both run around the full left hand side of the car next to the sill. It was a longer route but avoided the painful centre trim removal.

 

[Z4C_er]

Hmmm, if you remove the rear storage compartment, then you can feed wires directly through the bulkhead into the console area by merely lifting the handbrake and gearshift gaiter ashtray and trims. I was lucky when I removed the rear console as I used a little ratchet tool to get to the screws under the door, and therefore didn't have to remove the door. Thinking about it now, (but away from my car) could you pop off the little trim under the door (where the microswitch for the light is) and use a wire feeding tool to push through to the handbrake area? Anyway that's a bit of a last resort idea if you have no joy otherwise. Keep plugging away!

 

[Spriteracer]

Hi, sorry was away over the w/e and just seen your question re Siri. Regret I never have used it anyway (or Bixby) - my luddite tendencies kicking in ! so can't help with that one. Re calls on the move I agree and I never make outgoing without stopping, but it is useful to be able to acknowledge the occasional incoming business calls I get as I travel quite a lot.

 

[Darkangelv2]

Left hand side of the car is definitely a problem for the ‘alternator whine’ type sound. Play with your routing around the items tucked up behind the passenger footwell with the car running and find where/what to avoid over there

 

[veryverydarkblue]

Thanks all,

The heat and family expectations have slowed progress slightly over the past days.

No alternator whine, and on further investigation, I think the biggest issue was having it powered up with no background noise and engine off. It is actually just a slightly louder background hiss than comes through the stock speakers, and is still present without the speaker input connection. In normal usage, with the correct remote trigger (wire 'tap' hadn't pierced the outer near the power ariel), it's not noticeable at all.

Sealing up the sub boxes (milliput in the gaps, an mdf plug in the rectangular holes, and large washers with a nut and bolt in the rear, gromit for the wires through the small rear hole) means that there is now response (of sorts) down to around 30hz, but decays below c.50hz.

Now for some tuning.... The treble was still a bit bright at the '0' setting so will dial this back on the crossovers. The amp has a lot of settings to play with, but so far, sticking with full range on the fronts seems to be best, with the subs playing an additive role on the lower ranges. Will post my final settings

I mostly followed Z4C_ers 3-way install https://z4-forum.com/forum/viewtopic.php?f=2&t=105681 so I won't duplicate that here, but some pictures of my efforts so far below. The amp fits very nicely and locks in with a small padded bracket over the top. There's even still some space for some junk next to it

 

[ph001]

Great pics! How did you fix the baffle plates on for the rear subs just out of interest. I deliberated over it for some time!

 

[veryverydarkblue]

Great pics! How did you fix the baffle plates on for the rear subs just out of interest. I deliberated over it for some time!

OEM captive nuts, ordered with the sub grills, and currently just some DIY screws through the baffle. 2mm foam strip around the rest of the face to match the nuts. I contemplated rivnuts. I'm just on the lookout for some flanged headed screws now to spread the load a bit

 

[ph001]

Thats what I should have done . Any idea of the part number for those captive nuts?