[-nexus-]

I have a 2018 F82 M4 Competition with the HK system. I have found the bass to be basically non-existent. I have messed with the EQ and other settings to some improvement, but still nowhere near what I want.

My previous car was a N55 135i with the HK system and the bass in that is the best I've ever heard in a car without a boot/trunk sub. I had expectations the M4 would be just as good, but it's absolutely pathetic to the point that I think there is something wrong with the system.

I can hear some bass from the underseat woofers up around 60% volume, but by then the treble and general volume is too loud to be enjoyable.

I have trawled the forums here and it seems there's different experiences everywhere. I am tossing up about BavSound Ghost speakers to replace the HK woofers but I am not confident it will make the difference I want.

So my question is, are there any owners who feel their M4 with HK has basically no bass at reasonable listening volumes?

[NealfromNZ]

I agree with you on HK bass. It also lacks clarity

Needs a 10 inch trunk sub to fill out below 60hz. I tried mine with 140 rms into 8 ohms and whilst it can take quite a bit of power they won’t go low. They are at their best from 80 -200 hz.

I run Morels for underseat woofers in mine and they have better clarity and go deeper. But also run them with aftermarket amp and trunk sub.

[Billfitz]

If the underseats aren't giving output equal to the doors something is wrong, with the speakers or the amp or both.

[-nexus-]

I want to try to avoid a trunk sub if I can as I don't want to sacrifice the room. I want to get it at least to where my 135i was which was great as a stock HK system.
How would you rate the Morels without your amp and sub? Or have you not run them like that?

Billfitz, the underseat output is nowhere near the doors. I am thinking to take it to BMW as I have a couple weeks of warranty left since I bought my car as a BMW Certified Used vehicle.

[Billfitz]

You can try BMW, but their level of expertise with respect to audio is slim to none, and Slim just left town. They'll scan for codes, and if they don't find anything the usual response is 'there's nothing wrong'. They might just replace the woofers and/or amp, they might not. If they had audio testing equipment they could test both the woofers and the amp, but they don't. A well equipped and knowledgeable audio shop would.

The last thing you'd want to do is to replace either the amp or woofers without being sure they're at fault. IMO one or the other, if not both, are, but it's a shot in the dark which without testing. A wiring problem is a possibility, but wiring tends to either work or not.

[NealfromNZ]

Originally Posted by -nexus-

I want to try to avoid a trunk sub if I can as I don't want to sacrifice the room. I want to get it at least to where my 135i was which was great as a stock HK system.
How would you rate the Morels without your amp and sub? Or have you not run them like that?

Billfitz, the underseat output is nowhere near the doors. I am thinking to take it to BMW as I have a couple weeks of warranty left since I bought my car as a BMW Certified Used vehicle.

I’ve only run HKs and Morels with an aftermarket amp and dsp as started with base audio with 6.5s. I brought the HKs for their more robust enclosures initially but did run them for a couple of months. .

However the Morels aren’t a drop in speaker with HK amp with a 2 ohm load. The F8x platforms run with 8 ohm .Thresee are only an option when taking system to next level and replacing amp
.
Back to back with a mates Hk E91 335i they do go lower and had better clarity His e91 did sound quite good though.

Checking that you have bass output

Put a sound level app on your phone . Do a near field measurement on your left and right underseat woofers by putting the phone close to the speaker grill ( back seat with seat forward makes it easy )

Turn the volume to about half way and play the track below. With the sound app running on the phone check that you after getting output from left and right woofers. You should start hearing the test tones from 35hz. From this test you should be able to work out if both underseat woofers are working as this test is below the frequency where the door speakers kicks in.

If you get a reasonable level of output then the speakers and factory amp are performing.


.https://youtu.be/ukQ6OSs3dWo?si=htkkFAUnRQzpoChS

[johnung]

Originally Posted by -nexus-

I want to try to avoid a trunk sub if I can as I don't want to sacrifice the room. I want to get it at least to where my 135i was which was great as a stock HK system.
How would you rate the Morels without your amp and sub? Or have you not run them like that?

Billfitz, the underseat output is nowhere near the doors. I am thinking to take it to BMW as I have a couple weeks of warranty left since I bought my car as a BMW Certified Used vehicle.

I’ve had cars near end of warranty where dealers would just start swapping parts while the manufacturer was footing the bill. I make it a habit to take it to the local dealer and ask them to check the car out thoroughly before the warranty runs out. They always find and replace something. Saved me a ton of money over the years. If you can get them to swap out the amp and underseat subs, then it may solve your problem.

[-nexus-]

Thanks Neal, I gave that youtube bass test link a try with an audio meter on my phone. The volume was about 50% and I got about 78dB from each woofer, so based off that it does seem to be providing output, but even at that volume level I didn't feel like it was very loud. It was quite comfortable to listen to. I ran the same test on my 135i and whilst I know it's not an equal comparison, I was getting 83dB.

I tried another track that I just found on youtube which was very similar and just used the balance slider to switch left to right repeatedly to check for differences in sound between the two woofers. I discovered that the left woofer was reasonably clear, but the right woofer had a noticeable buzz/hum over the top of the bass, a bit like when an old speaker is turned up loud but not playing anything. I checked if it wasn't just a rattle of something else at a certain resonant frequency, but couldn't find anything.
I took a video but you'll need decent headphones or speakers that can reproduce the bass.

https://photos.app.goo.gl/Gj6A5Js4YCNY1rjKA

Would this be a sign the right woofer is dying?

[NealfromNZ]

It does sound like the right woofer is having issues, most likely voice coil damage , but also need to eliminate the amp channel. Bit hard to completely tell without hearing it in person.

If your handy with tools you could unbolt your seats take the covers off and swap the speakers over from left to right ( note , do not disconnect the seat wiring harness otherwise airbag error will come up )

Repeat test and you’ll know for sure if it’s right woofer or right channel on amp.

[visionaut]

??

We got big bass with our M4s over here…

[-nexus-]

I have the car booked in with BMW for them to take a look next week, if I get time before then I'll try swapping the woofers over to eliminate anything. I'll report back either after that or after BMW look into it.
Thanks for the help so far!

[-nexus-]

BMW took a look at the car and, as expected, claimed to have found nothing wrong. The best they could tell me was the EQ settings were not "correct" and adjusted them. There is still a distortion at even low volumes that I am surprised they didn't hear.
Their explanation why the M4 sound is different to the 135i is that the 135i is more "boxy" inside and has better bass acoustics. A dubious explanation at best, but no point arguing it as I do accept the cars are different.

A strange quirk I noticed was that the bass seems to be much better when listening to the radio. I rarely listen to the radio and normally stream Spotify over Bluetooth where the bass performance is poor. I might try some different media - USB, CD, aux cord etc to see if there's any difference.

I am closer to choosing Bavsound Ghost woofers though, but I'll do these few tests again to see.

[Billfitz]

Bavsound Ghosts are no better than stock, if even as good. If you must have them do yourself a favor and get them where Bavsound gets them: China. https://www.aliexpress.us/item/32568...%21rec%21US%21

The correct method of diagnosing the problem is to pull the woofers and install a pair that you know are good. If that cures the problem you know it was the woofers. If it doesn't the problem is further upstream.

[NealfromNZ]

Originally Posted by -nexus-

BMW took a look at the car and, as expected, claimed to have found nothing wrong. The best they could tell me was the EQ settings were not "correct" and adjusted them. There is still a distortion at even low volumes that I am surprised they didn't hear.
Their explanation why the M4 sound is different to the 135i is that the 135i is more "boxy" inside and has better bass acoustics. A dubious explanation at best, but no point arguing it as I do accept the cars are different.

A strange quirk I noticed was that the bass seems to be much better when listening to the radio. I rarely listen to the radio and normally stream Spotify over Bluetooth where the bass performance is poor. I might try some different media - USB, CD, aux cord etc to see if there's any difference.

I am closer to choosing Bavsound Ghost woofers though, but I'll do these few tests again to see.

Sounding like BS to me on the differences between platforms. I’d say cabin gain would be similar in both. But from your earlier check does sound like one of your woofers is on the way out. I’d complete the test to know if it’s woofer or amp channel. If it’s a woofer then replacement is the path.

With the bav sound woofers there’s an YouTube install video and a test after ( recording from phone lol )

But if you listen with headphones on bav will produce more lower end , but less in the 90 -120 hz region than HK so there are tradeoffs. Bit of eq at 100 hz may restore the difference between the BS and HK woofers .

[-nexus-]

Originally Posted by Billfitz

Bavsound Ghosts are no better than stock, if even as good. If you must have them do yourself a favor and get them where Bavsound gets them: China.

Well how about that. Certainly a lot cheaper!
I've heard so many for and against arguments for the Bavsound woofers that I'm quite on the fence about them, but Bavsound do offer the 100 day trial which I would be keen to take advantage of and I can return them if I don't like them.

Originally Posted by NealfromNZ

Sounding like BS to me on the differences between platforms. I’d say cabin gain would be similar in both. But from your earlier check does sound like one of your woofers is on the way out. I’d complete the test to know if it’s woofer or amp channel. If it’s a woofer then replacement is the path.

Yep I'll keep testing as I do believe something is still wrong, I just need to try to find some time to do it, especially swapping the woofers out to eliminate if its them or the amp.

[Billfitz]

Originally Posted by -nexus-

I've heard so many for and against arguments for the Bavsound woofers that I'm quite on the fence about them, but Bavsound do offer the 100 day trial .

Long trial periods are common with audio charlatans. The longer you keep listening to any audio gear the more you get used to it, so even if it's bad you eventually don't mind and end up keeping it.

The Bavsound business model is very common. Find an Asian source of inexpensive components, put your own name on them, preferably one that would make people think it's not Asian. Hype the bejesus out of them with totally unsupported claims of fantastic results, and charge twice what they're worth. It's not a new tactic by any means. The phrase 'caveat emptor' can goes back to when Egyptians sold one wheeled chariots to the Romans.

[NealfromNZ]

An alternative could be IA woofers. Cost wise they are priced quite well. Worth giving them a call to see how they’d run without a trunk sub. Pair is similar dollars to OEM single woofer replacement. Look to be dual voicecoil units so could be setup in series for an 8 ohm compatible HK amp load.

But be warned this could lead you down the slippery slope of a full system replacement over time 😀.

https://integralaudio.com/underseat-...s-f30-e90.html



.

[Billfitz]

Another pig in a poke. Speaker performance can be very accurately predicted using the speaker Thiele-Small specs and speaker modeling software. There are no specs available for Integral Audio. My advice is no specs, no sale.

[NealfromNZ]

True on the IA specs other than them being rated to 150 rms. That’s why I suggested a phone call as it’s not clear if they are ok as a stand alone verse augmented with a trunk sub.

But as I found with replacing HKs bass performance and clarity can be improved.

Just wouldn’t want the OP to drop money on S/H HKs to find they are partly blown , liquid or heat damaged and new ones aren’t low cost.

[Billfitz]

I wouldn't recommend new H-Ks either, as they're seriously over priced. Used is an option that doesn't cost an arm and a leg. Making sure that they're broken before trying to fix them is a must in any event.

[NealfromNZ]

Specs are up on the IAs. But sadly they are closing shop soon.

[Billfitz]

The specs aren't bad, but the critical X-max that shows how much output they're capable of is missing.