More details for KEF Audio

[Fido]

Putting fancy hi-if into a car is never going to be easy. There is very little about the interior of a car that is acoustically friendly as everything is designed with its primary function in mind and not the audio performance. Who at home has speaker cabinets that are shaped like car doors? And who sits with their head 6 inches from their window? Add to that the A-symmetry of having the key occupant off-set in the auditorium. Plus the constant competition with air and structure borne noise that varies with road and engine speed and you have a pretty daunting task. So given the constraints, unless the interior team do a really fantastic job and fill the car with dead sheep to absorb all of the stray noise, or employ some fancy new acoustic noise cancelling (this works well with predictable noise, like engine order noise, tyre thrum and some wind noise. But less well with more random inputs like rain/puddles, gusts and potholes). What can you do? Well firstly try and make it as quiet as possible in the car. And then provide as many, reasonable quality sound sources as you can pointing towards the occupants. Then digitally manipulate the whole affaire to make it sound as least compromised as possible. The other problem is that by and large, more watts means more heat and power demand to manage, and better speakers mean bigger, heavier magnets or very sexy and expensive materials. Most manufacturers now make a pretty good fist of making a half decent in-car audio system, I anticipate that the base audio will be fit for purpose. The premium system will have more oomph but will be no less compromised in purist terms, although most will feel it sounds better.

 

[Tokion]

Do you mean improving by adding extra earthing to the negative terminal by using gold plated ICE earth bolts and OFC earthing wire terminals

Possibly. I will discuss the best approach with the engineers/technicians. A significant part they offer is a very compact super-capacitor (a very high value in a quite compact format). I think the initial step will be to map out electrically in a circuit diagram what the KEF premium audio system really is. I suppose a current owner of any FE car could actually have this done already. It would help everyone on this forum to have a complete description of the entire EMIRA KEF audio system in as much detail as possible. (I am an audio enthusiast, but not able to give exact technical advice here. And certainly not typing in any instructions that may lead to damage or faults.)

 

[Kimmax]

I noticed something strange.. When driving with the windows down the bass suddenly gets stronger and some of the left over rattle (it was worse, now it's 'fixed' and I don't have the nerves to deal with it further) is gone as well. Kinda like the subwoofer struggles to breath with the windows closed?

 

[Tokion]

I noticed something strange.. When driving with the windows down the bass suddenly gets stronger and some of the left over rattle (it was worse, now it's 'fixed' and I don't have the nerves to deal with it further) is gone as well. Kinda like the subwoofer struggles to breath with the windows closed?

Interesting and useful information.

Here is a description of the “fresh air” speaker technology (used for The subwoofer of the Emira premium car audio system - the KEF speakers only cover midrange and treble) by the Australian company that designed it:

FRESH AIR SPEAKER – Bluacs

bluacs.com

 

[Fido]

A loudspeaker creates vibrations that propagate through the air as sound. The front face of the speaker has to be isolated from the rear face as these are effectively +ve and -ve sounds that if allowed to interact will cancel one another out. This is usually achieved with an ‘infinite baffle’ better know as a sealed box with one face of the speaker cone on the inside and the other on the outside. Unfortunately a sealed box, especially a vey small one such as may be necessary in a car, can act as a spring and mute the performance of the speaker. A vented enclosure can usually have a port that is tuned to minimise the phase difference and even enhance the volume of sound heard.
A fresh air speaker is pretty much the same as an infinite baffle except in this case the listener is inside the box and not on the outside. With the box sealed the air in the car will act as a spring especially if the woofer is a long throw device. Opening the window will change the sound because you are opening a port in the infinite baffle arrangement and allowing the speaker to breathe as you say. Whether this change is an improvement or a degradation depends on the design assumptions for the speaker system, but as ever, how we feel about the result is entirely subjective.
Anyway, as I said before, the whole affaire is so horribly compromised by imposed design constraints that nobody could consider any car system high fidelity. It should though, be possible to get a half decent result with some digital manipulation. Spending money on OFC copper or silver cabling to preserve the purity of the original signal? I think not!

 

[Ceejay]

Ok, so I’ve had mine for 2 weeks and 400 miles, I didn’t try the sound system on my test drive because I was much more interested in the cars sound and getting a more mechanical connection during the time I had. I must admit some of the comments on the KEF system concerned me but I needn’t have worried. I use CarPlay on my iPhone with all of my music taken from CD, yes I am that old! I have to say the system is more than powerful enough, bass is strong, detail is very good and the sound stage for a car is quite impressive. Wind noise in my car is minimal too. Are they really varying that much?

 

[Mh59]

I noticed something strange.. When driving with the windows down the bass suddenly gets stronger and some of the left over rattle (it was worse, now it's 'fixed' and I don't have the nerves to deal with it further) is gone as well. Kinda like the subwoofer struggles to breath with the windows closed?

Interesting - I thought this was the case too but I haven't experimented enough with it to be 100% sure but given the explainers above, this would seem accurate.

My audio remains shocking. To the point I dont use it. Every time I turn it on, I turn if off again after a few minutes as the Bass vibrations render it unlistenable. I have explained it before as a cheap system (I know it isn't) - the noise you would expect from a £10 portable speaker if you turned the volume beyond halfway. Thats the only way I can describe it.

The bass is shockingly bad and I have tried turning the equaliser down to the default (I would normally have it turned up a few notches from the top) with no difference. This isn't to do with settings but more of a poor / failed component quality matter I feel.

That said, I have almost given up on trying to have it resolved as I dont want the car ripped to bits to replace components if its not going to have the desired effect or create further issues down the line.

 

[Kimmax]

Interesting - I thought this was the case too but I haven't experimented enough with it to be 100% sure.

My audio remains shocking. To the point I dont use it. Very time I turn it on, I turn if off again after a few minutes as the Bass vibrations render it unlistenable. I have explained it before as a cheap system (I know it isn't) - the noise you would expect from a £10 portable speaker if you turned the volume beyond halfway. Thats the only way I can describe it.

The bass is shockingly bad and I have tried turning the equaliser down to the default (I would normally have it turned up a few notches from the top) with no difference. This isn't to do with settings but more of a poor quality matter I feel.

That said, I have almost given up on trying to have it resolved as I dont want the car ripped to bits to replace components if its not going to have the desired effect or create further issues down the line.

Hit your dealer up. Initially, mine was also unusable. Dealer dismounted the subwoofer and reattached everything. Nothing was swapped, but I guess something wasn't fastened all the way. It's much better now. Sometimes it still generates some bad vibrations on certain frequencies, but at least it's usable now.

Subwoofer access is fairly easy. I could pick up the car the next day already, nothing to worry about. I'm planning on getting the panel off myself again and seeing for myself what's going on. Maybe some insulation can be fitted somewhere to finally get this sorted. Maybe I'll let a real audio shop look over it if I find someone that seems trustworthy to work on the car.

 

[Mh59]

Hit your dealer up. Initially, mine was also unusable. Dealer dismounted the subwoofer and reattached everything. Nothing was swapped, but I guess something wasn't fastened all the way. It's much better now. Sometimes it still generates some bad vibrations on certain frequencies, but at least it's usable now.

Subwoofer access is fairly easy. I could pick up the car the next day already, nothing to worry about. I'm planning on getting the panel off myself again and seeing for myself what's going on. Maybe some insulation can be fitted somewhere to finally get this sorted. Maybe I'll let a real audio shop look over it if I find someone that seems trustworthy to work on the car.

Thanks. I will mention it when I drop off tomorrow. If its quick and easy, hopefully they can at least try to reseat it all.

I'd also be happy to have a look myself but wouldn't want to be taking panels off that are not "easy access" types. I will see what they say tomorrow first.

 

[Kimmax]

Thanks. I will mention it when I drop off tomorrow. If its quick and easy, hopefully they can at least try to reseat it all.

I'd also be happy to have a look myself but wouldn't want to be taking panels off that are not "easy access" types. I will see what they say tomorrow first.

I'll have to check the docs again, but I think the panel is only clipped in.

 

[digilotus]

I would definately work with your dealer on this. Its obviously taking away from your enjoyment of the car and so it needs to be resolved. I understand that access to the subwoofer is relatively straightforward so should be simple to diagnose the rattle(s) and remove them.

 

[Mh59]

I would definately work with your dealer on this. Its obviously taking away from your enjoyment of the car and so it needs to be resolved. I understand that access to the subwoofer is relatively straightforward so should be simple to diagnose the rattle(s) and remove them.

I'd be interested to just disconnect the sub, to see if there is an immediate improvement then it's clear what needs looking at. I have the full manuals to hand so will take a look. I am assuming based on the rattle that the sub is pretty much behind the drivers seat. I haven't had a fumble around that area to be honest. I will take a look this afternoon.

 

[KJD]

This might help.

A28C7BE1-48E5-4CF6-A5D2-147E0F597CAC.jpeg

www.emiraforum.com

 

[Mh59]

Interesting - I thought this was the case too but I haven't experimented enough with it to be 100% sure but given the explainers above, this would seem accurate.

My audio remains shocking. To the point I dont use it. Every time I turn it on, I turn if off again after a few minutes as the Bass vibrations render it unlistenable. I have explained it before as a cheap system (I know it isn't) - the noise you would expect from a £10 portable speaker if you turned the volume beyond halfway. Thats the only way I can describe it.

The bass is shockingly bad and I have tried turning the equaliser down to the default (I would normally have it turned up a few notches from the top) with no difference. This isn't to do with settings but more of a poor / failed component quality matter I feel.

That said, I have almost given up on trying to have it resolved as I dont want the car ripped to bits to replace components if its not going to have the desired effect or create further issues down the line.

I did some testing this morning on my way to drop the car at the dealer. I had a heavy bass dance mix playing, 3 or 4 different songs with differing bass, instrument levels etc for a bit of variety.

With the windows up, even when the volume was cranked up to about 85-90%, the rattling was there but not anywhere like what I would consider "problem levels".

However, as soon as I opened the window the vibrations from behind me (the subwoofer I assume) were very prominent. When I then opened the passenger window too, it was at its worst. There seems to be a clear link between the "fresh air subwoofer" and the flow of air in the vehicle affecting audio performance.

Having briefly discussed this with the dealer, both of us not having heard of this before, it seems the simple fix would be to disable or limit the subwoofer when the windows go down. This would be a very simple thing to implement within one of the ECU's (by the manufacturer).

One theory I have is that due to the new-ness of the vehicle, its entirely possible KEF didn't have a moving vehicle for the production of the system and have built it in factory using an Emira mock shell, for testing internal dynamics and sizing for components. If they didn't have a moving vehicle (and / or didn't test with a window open), then they would not know about this issue. I will test later but I also think this is an issue when the vehicle is stationary, with the window open (which would suggest an electrical issue maybe, rather than airflow)

That said, this might not be a problem for others and would need further people to test. It seems to be an issue at all speeds so could easily and quickly be tested by existing owners. Hopefully we will hear more from others and we can go from there. Perhaps contacting KEF to see what their thoughts are and look at a simple solution to control the sub when the windows are open. In theory this behaviour might be the same when the AC is on full blast, as it might be in the summer for example. I can try that when I get my car back later.

 

[Mh59]

I will also try to record some samples to give others an idea of the impact as someone with more experience on these matters might know what's happening with a sample.

 

[patpat]

I will also try to record some samples to give others an idea of the impact as someone with more experience on these matters might know what's happening with a sample.

Might be a stupid query but are you confident that it's the sub that is the issue?
I mean if the vibrations are high when you roll down the windows then I wonder if it could be vibrations on the window glass or door assembly that might be resonating? Have you verified if same is happening with dealer car?

 

[Nova]

I did some testing this morning on my way to drop the car at the dealer. I had a heavy bass dance mix playing, 3 or 4 different songs with differing bass, instrument levels etc for a bit of variety.

With the windows up, even when the volume was cranked up to about 85-90%, the rattling was there but not anywhere like what I would consider "problem levels".

However, as soon as I opened the window the vibrations from behind me (the subwoofer I assume) were very prominent. When I then opened the passenger window too, it was at its worst. There seems to be a clear link between the "fresh air subwoofer" and the flow of air in the vehicle affecting audio performance.

Having briefly discussed this with the dealer, both of us not having heard of this before, it seems the simple fix would be to disable or limit the subwoofer when the windows go down. This would be a very simple thing to implement within one of the ECU's (by the manufacturer).

One theory I have is that due to the new-ness of the vehicle, its entirely possible KEF didn't have a moving vehicle for the production of the system and have built it in factory using an Emira mock shell, for testing internal dynamics and sizing for components. If they didn't have a moving vehicle (and / or didn't test with a window open), then they would not know about this issue. I will test later but I also think this is an issue when the vehicle is stationary, with the window open (which would suggest an electrical issue maybe, rather than airflow)

That said, this might not be a problem for others and would need further people to test. It seems to be an issue at all speeds so could easily and quickly be tested by existing owners. Hopefully we will hear more from others and we can go from there. Perhaps contacting KEF to see what their thoughts are and look at a simple solution to control the sub when the windows are open. In theory this behaviour might be the same when the AC is on full blast, as it might be in the summer for example. I can try that when I get my car back later.

It's possible that you are reaching the mechanical limit of the subwoofer. The clue is that the problem got worse when you opened the window. The fresh air subwoofer design essentially puts the listener inside a large semi-sealed box. The air volume inside the vehicle acts as a spring that resists the motion of the woofer. With a window open, the air spring effect becomes less, allowing the subwoofer cone to move much more with the same input signal level. This may allow the subwoofer to reach the limit of its mechanical travel, whereby the voice-coil former strikes the back of the magnet, making a loud and sharp clack-clack sound.

It's also possible that one of the subwoofer drivers is defective or out of spec, but the chances of this are rather small for mass-produced subwoofer drivers.

 

[Nova]

Might be a stupid query but are you confident that it's the sub that is the issue?
I mean if the vibrations are high when you roll down the windows then I wonder if it could be vibrations on the window glass or door assembly that might be resonating? Have you verified if same is happening with dealer car?

He can try opening a door instead of just rolling the window down...

 

[patpat]

He can try opening a door instead of just rolling the window down...

If it's an issue with the glass then the issue will be there even if the door is opened since the windows are frameless

 

[FederGigant]

Today I fixed my slight rattle problem with the sub. You can hear it very well when the engine is shut off, but not so much while driving. Nevertheless, I didn't like it. To show you where the problem came from, I stole the following pic out of the forum and drew an arrow on it:

What you see there is a pressure relief valve. You will find one or two of those in every car to release the pressure that's bilding up while you are slamming your doors In a bigger car they are usually located somewhere in the very rear. As you might see, Lotus placed it exactly next to the subwoofer and therefore the sound pressure - even at VERY low volumes - makes those membranes flatter and create a rattle noise. Easy fix was to click it out of place, put some 6mm self adhering Armaflex on each of the membranes from the other side and put it back in place. Now there is more weight to them and they won't move anymore due to the woofer. Of course they still work just fine when closing a door.
The removal of the trim panel is straight forward. Start where the luggage net is hooked and just pull from there. There are two clips in the front top and buttom and that's it. After you unclipped them, you can pull the panel out with some force. Only tricky part is the top, because it goes under that speaker grille lookalike.