Underseat Subwoofer upgrade for HK F30

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Gaffer
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Underseat Subwoofer upgrade for HK F30

Post by Gaffer » 29 Dec 2017, 21:10

Hi folks.

I have just got a couple of these (Focal IF-BMWSUB.V2) as a pair of direct drop-in replacements to the OEM HK underseat subs.

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In the US, they mainly buy Bavsound subs which are a small shop that commissioned their own design, got 'em made in China and took off from there (I only had Focal and Vibe to choose from here in the UK, which I think are better). Luckily, they have a video of how to do the replacement of their subs, which should be the same regardless of the sub you use:



Based on the Bavsound videos, why do they remove the whole unit? Why not just lift the seat, remove the cover, then directly unscrew the OEM speaker cone alone and unclip the electrical plug to remove? This would leave a hole to directly drop in the replacement. Why do you have to go to the extra hassle of unclipping extra things and removing the whole sub unit, plastic enclosure included?
I think I'm missing something here but I can't for the life of me see why you can't simply replace the cone in situ?

Has anyone done similar and can advise me please? :?
'15 F30 330d xDrive MSport+ in Black Sapphire ......... HmKd Audio + Focal IFBMW-SUB.V2 ......... Gafferlicious.com

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Re: Underseat Subwoofer upgrade for HK F30

Post by Gaffer » 30 Dec 2017, 00:48

EDIT: Doesn't matter, I just found the Bavsound updated video that answers that exact question:



Turns out you can simply swap out the cones directly without removing the enclosure :thumbup: .

Mine arrived today so i'll be installing them tomorrow:

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'15 F30 330d xDrive MSport+ in Black Sapphire ......... HmKd Audio + Focal IFBMW-SUB.V2 ......... Gafferlicious.com

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Re: Underseat Subwoofer upgrade for HK F30

Post by Gaffer » 30 Dec 2017, 16:36

Just installed them this morning :). A few things worth noting if you want to do this (in addition to that Bavsound video above):
  1. These are better than I expected. The bass is massively improved from stock but nowhere near what a boot mounted sub can do (so if you want serious levels of SPL, go for a boot install). If you want a big improvement on OEM but want to keep things OEM in looks then these drop in replacements are great VFM. Things will only get better as I run them in over the next few weeks :d.
  2. I have heard the Bavsound replacements in a friends F31 (not sure where he got them from as he's in the UK) and these Focal's are already sounding far better imo. Same punch and control but with even more depth/extension. Plus only £275 c.f. the £447 he paid.
  3. If you have the HK 16spkr system you don't need to do any re-coding or wire splicing, these Focals simply drop straight in and the OEM connector fits snugly into the female Focal plug socket.
  4. The front seat bolts were on ridiculously tight. So tight in fact, they defeated my Bosch impact driver (the first things to do so around the house) so you'll have to resort to good old elbow grease to loosen them (the 2 rear bolts were easy to remove).....I had to use a lot of steady force for the initial loosening and you have to be careful here not to round out the torx head (apply firm pressure and you'll be fine). Also worth using a spray of WD40 on those front bolts and waiting a minute or two for it to seep in before giving them a go.
  5. It is EASY to simply remove the cone - unscrew the 4 torx screws, use a flat-head screw driver in the edge to loosen the cone basket a bit, then simply pull it out ready for the new one (I still have no idea why people go to the extra hassle of removing the whole assembly - this way is much easier). Finally, unclip the connector and you're done.
  6. You have to buy V2 of the Focals because the mounting depth needs to be a bit thicker....so you have in the box, the mounting ring + spkr cone + metal grill - these all fit comfortably in place. This also means you need the supplied longer screws (allen key not torx) that come with the sub in order to screw them in due to the thicker depth.
  7. Now check the sub works before continuing (just turn the radio on, you should feel the vibrations in the speaker).
  8. Once all screwed down, you're meant to have finished, but as I wanted the OEM look I wanted the OEM plastic grills on top as well. This can be done as long as you lightly tighten them (finger tight) and watch for the amount of flex in the grill. The seat will also "clamp down" on them so you don't need to worry about them rattling.
  9. When re-mounting the seat, FIRST finger tighten all 4 bolts down so that the seat is aligned, THEN tighten up fully (don't tighten each one from scratch in turn).
  10. Because these are so much better than OEM, they have better frequency characteristics so you'll have to re-visit your Bass and EQ settings again (e.g. you may find you can turn the bass up as the sound is more controlled and less flabby now, or that you need to turn it down as it is more abundant than before). I'm also finding I don't have to listen as loud for it to sound as good, the bass comes through at lower volumes than OEM and doesn't seem to be drowned out as much when on the move.
In total takes about 45min start to finish (most of which was taken up trying to carefully loosen those bloody front bolts on the seats) and well worth the small outlay imho :thumbsup:.

BTW, here is the eBay seller (autoradio-center) I got them from, the £275 included delivery (the listing gives a price of £265, but when you pay via paypal it inexplicably goes up to £275 on completion so remember eBay is inaccurate re:exchange rates in the listings - probably to entice you to buy and then hits you with the real price AFTER you have completed the paypal payment :roll:).

https://www.ebay.co.uk/itm/Focal-IFBMW- ... 2749.l2649

Took 7 days to arrive from France with a tracking number and, to be fair, that price is still fantastic for both (every UK shop sells these for £380 per pair :shock:).
'15 F30 330d xDrive MSport+ in Black Sapphire ......... HmKd Audio + Focal IFBMW-SUB.V2 ......... Gafferlicious.com

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Re: Underseat Subwoofer upgrade for HK F30

Post by Gus247 » 02 Jan 2018, 13:40

Excellent write up - thank you... I'm on the lookout for an F31 at the moment so hoping that I can find one in the spec I want, with the bits I want (HK audio being one) for the price I want.... (Don't want too much eh?!?! :)) )

I'll definitely look at these if the HK kit is fitted to the one I end up with... :thumbup:
aka Andy

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Re: Underseat Subwoofer upgrade for HK F30

Post by cockneyrebel » 02 Jan 2018, 18:35

Great write up, thanks for the Info 👌.
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Re: Underseat Subwoofer upgrade for HK F30

Post by Gaffer » 15 Jan 2018, 12:54

Thanks guys :)

Sold the OEM subs for £20 so that brings cost of these down to £255 for me :d.

Thought I'd also update here about my current EQ settings for the system. I have a calibrated mic (for home Hi-Fi = the miniDSP UMIK-1) which I use with REW software to get a frequency analysis. My results broadly matched those of someone else who did similar and got roughly these settings.

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Things of note to add about the system are:
  • The individual levels (listed below) look a bit wild because the HU volume applies a contour curve dynamically which changes the spectrum.....so to get repeatable results you have to listen at the same volume you did the calibration in. I tend to listen at roughly 2/3 - 3/4 the max vol so that's what I used to calibrate.
  • Q value of the EQ levels is too broad meaning that adjacent frequencies are also dragged up and down when you change one specific frequency. So, for example, putting 500Hz up 4 notches will also pull 200Hz and 1kHz up a couple and also 100Hz and 2kHz up a notch. This makes isolating the frequencies VERY difficult.
  • L7 is like a spatialiser and is something I would normally NEVER apply at home (hifi/tv/radio etc) because it is not tonally accurate. However, sound in a car is always compromised anyway as you're in an echoey box with things like road noise etc. so I don't look for "perfect sound" as I don't believe it's possible in this environment (I have a perfect environment at home on my naim/primaluna/tannoy system). What L7 is brilliant for is lifting up the soundstage from the bottom of the steering wheel to above the dashboard.....so the benefits outweigh the compromise imho.
  • I think it’s always better to do negative cut (ie. limit power) to specific bands than to do positive add (ie. try to create power) to specific bands.
  • At the levels I'm listening, a notch change = a 1dB change; but this is complicated by the ridiculously wide Q that mucks up nearby bands (see above).
  • There is a "gap" at about 140Hz where the door speakers cannot extend down to (nor should they) but the OEM subs cannot fill up to either (a problem with the HK subs). The OEM bass is also more woolly and less precise than the Focal replacements. This means the Focals have much less distortion and are able to correctly "fill in" most of that 140Hz trough so 200Hz can be raised a bit more (as can overall bass level).
  • If you look at the bottom red trace (corrected L7 ON) the frequency curve is fairly flat from above 200Hz (midrange & treble), so I have left those alone.
Treble: 0
Bass: +2 +3
L7: ON
100Hz: +7
200Hz: -6 -4
500Hz: -4
1kHz: +5
2kHz: -4
5kHz: +2
10kHz: -1

The changes with the Focal subs are in red.

This system sounds much better and as the subs are getting run-in, sounding better day by day. The subs now vibrate the seats and the rear view mirror as well (objects blur when bass appears). Not as good as a standalone boot install, granted, but fantastic vfm for a direct drop-in replacement imho :-bd.
'15 F30 330d xDrive MSport+ in Black Sapphire ......... HmKd Audio + Focal IFBMW-SUB.V2 ......... Gafferlicious.com

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