What Car Audio

[JimH]

Hi thanks for sharing... when I read it, it has no detail about the amp or dsp used

KEF are generally known as a speaker manufacturer - there's one amplifier on their website. Doesn't mean that they haven't been involved in the in-car development with Lotus but yes, detail is scant otherwise....

 

[TomE]

Behind the seats, in the side plastic trim, from memory (this was covered in a bit of detail on one of the other Lotus forums).

Is it this grille in the rear, so higher up at shoulder height rather than lower down? Or is that just a conventional speaker rather than the sub? I'm no audio expert!

None of my pictures of the rear show any kind of grille in the lower section, but it is a show car and may have been omitted. There is another one of these on the opposite side.

 

[andrew6382]

Is it this grille in the rear, so higher up at shoulder height rather than lower down? Or is that just a conventional speaker rather than the sub? I'm no audio expert!

None of my pictures of the rear show any kind of grille in the lower section, but it is a show car and may have been omitted. There is another one of these on the opposite side.

View attachment 2330

may not be subs, but think its going to be part of the HIFI, meant to be 10 speakers so good place for mid range well spotted

 

[Eagle7]

A sub is generally a single speaker. Sub bass frequencies are omni directional so you don't need a pair. Those are probably part of the KEF system.

 

[Nova]

That sub stuff is very clever. If the claims for c. 10x higher SPL than normal subs stand up it's going to be very interesting in such a small cabin. I just put an audison system around the same power in my yaris with a sub and it's more than loud enough (granted I am somewhat older than when I had two 12" subs in my old mini.)

Anyway, I don't doubt Kef will have done enough R&D and got the tech side of things right. But I do hope they've properly tested it in a car, considered acoustic deadening requirements, etc. Makes so much difference.

I think the marketing guys got a little bit carried away with those claims. 10dB increase in output is significant but it's not 10 times higher SPL. Subjectively speaking, 10dB higher SPL is roughly perceived as twice as loud.

Normal subwoofer implementations essentially place the listener inside the larger box of a band-pass design. In this design, low-frequency roll-off can be significant depending on the size of the box that the subwoofer is placed in. The larger the box, the more significant the roll-off. This is why small box subwoofers became all the rage. In addition to taking up less space, they provided deeper extension into the lower bass region. Small box woofers are, however, incredibly inefficient due to their heavy cone mass that must be used to balance the stiff suspension that is needed to match the small volume of the box. The way to combat this is to increase the magnet size, which is why modern car subwoofers have such humongous magnets.

The reason the fresh air sub works differently is that it vents to the outside of the car. So instead of sitting inside a bandpass box, the user is sitting inside a semi-sealed box. The deep-bass roll-off for a semi-sealed box is much shallower than that for a bandpass box, so the listener naturally gets more bass output. Additionally, since the interior volume of a car is huge, the subwoofer can use a fairly compliant suspension and thus very light cone mass to get the desired resonant frequency tuning. This makes for a potentially very efficient driver if combined with a reasonably-sized magnet.

It's just that most people don't go cutting holes in their car's chassis when installing subwoofers so this is rarely done for DIY or even most professional car audio systems.

 

[andrew6382]

A sub is generally a single speaker. Sub bass frequencies are omni directional so you don't need a pair. Those are probably part of the KEF system.

Yep, like you say subs, you dont need two..... but boy would be epic with two but like you said and i perhaps mid range

 

[Johnson]

Is it this grille in the rear, so higher up at shoulder height rather than lower down? Or is that just a conventional speaker rather than the sub? I'm no audio expert!

None of my pictures of the rear show any kind of grille in the lower section, but it is a show car and may have been omitted. There is another one of these on the opposite side.

View attachment 2330

Yep, I think that grill is too big to be the sub, Tom. The subwoofer vent is actually quite thin… one of the great advantages of the Aussie design.

I think the marketing guys got a little bit carried away with those claims. 10dB increase in output is significant but it's not 10 times higher SPL. Subjectively speaking, 10dB higher SPL is roughly perceived as twice as loud.

Normal subwoofer implementations essentially place the listener inside the larger box of a band-pass design. In this design, low-frequency roll-off can be significant depending on the size of the box that the subwoofer is placed in. The larger the box, the more significant the roll-off. This is why small box subwoofers became all the rage. In addition to taking up less space, they provided deeper extension into the lower bass region. Small box woofers are, however, incredibly inefficient due to their heavy cone mass that must be used to balance the stiff suspension that is needed to match the small volume of the box. The way to combat this is to increase the magnet size, which is why modern car subwoofers have such humongous magnets.

The reason the fresh air sub works differently is that it vents to the outside of the car. So instead of sitting inside a bandpass box, the user is sitting inside a semi-sealed box. The deep-bass roll-off for a semi-sealed box is much shallower than that for a bandpass box, so the listener naturally gets more bass output. Additionally, since the interior volume of a car is huge, the subwoofer can use a fairly compliant suspension and thus very light cone mass to get the desired resonant frequency tuning. This makes for a potentially very efficient driver if combined with a reasonably-sized magnet.

It's just that most people don't go cutting holes in their car's chassis when installing subwoofers so this is rarely done for DIY or even most professional car audio systems.

Great analysis Nova. My understanding is that the sub is essentially an ”infinite baffle” sub, so potential frequencies are very low. Although I’m curious: the cabin of the car isn’t infinite, so (with the windows up and fan off) is there any influence on the sub’s movement? Infinite baffle subs tend to have quite floppy surrounds to encourage displacement, but the Emira cabin is smaller than most…

 

[andrew6382]

I think the marketing guys got a little bit carried away with those claims. 10dB increase in output is significant but it's not 10 times higher SPL. Subjectively speaking, 10dB higher SPL is roughly perceived as twice as loud.

Normal subwoofer implementations essentially place the listener inside the larger box of a band-pass design. In this design, low-frequency roll-off can be significant depending on the size of the box that the subwoofer is placed in. The larger the box, the more significant the roll-off. This is why small box subwoofers became all the rage. In addition to taking up less space, they provided deeper extension into the lower bass region. Small box woofers are, however, incredibly inefficient due to their heavy cone mass that must be used to balance the stiff suspension that is needed to match the small volume of the box. The way to combat this is to increase the magnet size, which is why modern car subwoofers have such humongous magnets.

The reason the fresh air sub works differently is that it vents to the outside of the car. So instead of sitting inside a bandpass box, the user is sitting inside a semi-sealed box. The deep-bass roll-off for a semi-sealed box is much shallower than that for a bandpass box, so the listener naturally gets more bass output. Additionally, since the interior volume of a car is huge, the subwoofer can use a fairly compliant suspension and thus very light cone mass to get the desired resonant frequency tuning. This makes for a potentially very efficient driver if combined with a reasonably-sized magnet.

It's just that most people don't go cutting holes in their car's chassis when installing subwoofers so this is rarely done for DIY or even most professional car audio systems.

Well..... pun intended Sounds like we might get some good tunes to cruise down the M2 at 2 in the morning on the way to France roll on 1812

 

[Nova]

Great analysis Nova. My understanding is that the sub is essentially an ”infinite baffle” sub, so potential frequencies are very low. Although I’m curious: the cabin of the car isn’t infinite, so (with the windows up and fan off) is there any influence on the sub’s movement? Infinite baffle subs tend to have quite floppy surrounds to encourage displacement, but the Emira cabin is smaller than most…

Right... true infinite baffle would require two very large spaces separated by a divider. So if you mounted a subwoofer on a wall between two rooms, that would be pretty close to a true infinite baffle. Inside a car's interior, even for some of the larger cars, there will be some effect of the interior room on the acoustics to bring it away from the infinite baffle ideal, this would be especially true of a smaller car like the Emira.

My understanding is that with a fresh-air subwoofer like this, rolling down the windows will significantly decrease subwoofer output since the front and back of the woofer would then share a common air volume for bass frequencies. This is the opposite of traditional subwoofer implementations where opening the window usually significantly increased low bass output due to substantial elimination of the band-pass effect.

 

[VL3X]

This may be a silly question, but do Lotus typically come with a spare tire or are they run flats (I can't imagine there being room for a spare anywhere in the Emira)? I ask because in my GTI, the Fender audio system has the subwoofer sitting in the center of the spare tire below the trunk mat. In my STIs, the subwoofer was under the driver seat.

 

[donskibeat]

Certainly won't come with a spare tyre! no where to put one , suspect they will just come with a can of tyre weld in the boot

 

[Eagle7]

I think the marketing guys got a little bit carried away with those claims. 10dB increase in output is significant but it's not 10 times higher SPL. Subjectively speaking, 10dB higher SPL is roughly perceived as twice as loud.

Normal subwoofer implementations essentially place the listener inside the larger box of a band-pass design. In this design, low-frequency roll-off can be significant depending on the size of the box that the subwoofer is placed in. The larger the box, the more significant the roll-off. This is why small box subwoofers became all the rage. In addition to taking up less space, they provided deeper extension into the lower bass region. Small box woofers are, however, incredibly inefficient due to their heavy cone mass that must be used to balance the stiff suspension that is needed to match the small volume of the box. The way to combat this is to increase the magnet size, which is why modern car subwoofers have such humongous magnets.

The reason the fresh air sub works differently is that it vents to the outside of the car. So instead of sitting inside a bandpass box, the user is sitting inside a semi-sealed box. The deep-bass roll-off for a semi-sealed box is much shallower than that for a bandpass box, so the listener naturally gets more bass output. Additionally, since the interior volume of a car is huge, the subwoofer can use a fairly compliant suspension and thus very light cone mass to get the desired resonant frequency tuning. This makes for a potentially very efficient driver if combined with a reasonably-sized magnet.

It's just that most people don't go cutting holes in their car's chassis when installing subwoofers so this is rarely done for DIY or even most professional car audio systems.

After reading the links to KEF and Bluacs, it seems that Lotus worked with those guys to make changes in the interior they requested and needed. The audio performance of this setup may be a bigger deal than anyone realizes.

 

[VL3X]

After reading the links to KEF and Bluacs, it seems that Lotus worked with those guys to make changes in the interior they requested and needed. The audio performance of this setup may be a bigger deal than anyone realizes.

Meanwhile I can't get a yellow TDC stripe on my steering wheel.

 

[Nova]

After reading the links to KEF and Bluacs, it seems that Lotus worked with those guys to make changes in the interior they requested and needed. The audio performance of this setup may be a bigger deal than anyone realizes.

I read that too, but I'm not so sure they changed the interior design of the car. What's more likely is that the portion of the door panel behind the speaker grill, that portion that is hidden from view and is therefore usually a mess of black plastic in the typical car stereo, may have a smooth and gradual waveguide design to it that flows more naturally to match the curvature of the Uni-Q driver woofer cone, which itself is an extension of the waveguide for the coaxial tweeter. If they did this, it would reduce some of the problematic diffraction that occurs when there isn't such a smooth transition from the driver to surrounding surfaces. In the grand scheme of things, I don't know how much benefit this adds. I guess better response predictability is always a plus.

Regardless, there are 10 channels in the car, so the DSP is definitely the thing that's doing the heavy lifting here in terms of time alignment and listening position response curve.

 

[andrew6382]

After reading the links to KEF and Bluacs, it seems that Lotus worked with those guys to make changes in the interior they requested and needed. The audio performance of this setup may be a bigger deal than anyone realizes.

Yes I think you might be right, can not see KEF wanting to do an half ass job.... Am sure they would want to enter this new market place for them with a system that sets a high standard

 

[andrew6382]

I read that too, but I'm not so sure they changed the interior design of the car. What's more likely is that the portion of the door panel behind the speaker grill, that portion that is hidden from view and is therefore usually a mess of black plastic in the typical car stereo, may have a smooth and gradual waveguide design to it that flows more naturally to match the curvature of the Uni-Q driver woofer cone, which itself is an extension of the waveguide for the coaxial tweeter. If they did this, it would reduce some of the problematic diffraction that occurs when there isn't such a smooth transition from the driver to surrounding surfaces. In the grand scheme of things, I don't know how much benefit this adds. I guess better response predictability is always a plus.

Regardless, there are 10 channels in the car, so the DSP is definitely the thing that's doing the heavy lifting here in terms of time alignment and listening position response curve.

Oh yes the DSP is going to play a very big part, have they made there own, Or brought in a companys kit that already understands the systems

It would seem KEF have made a DSP before

Introduction to the LS50W Part 2 - The DSP

us.kef.com

 

[Mike-engel]

Oh yes the DSP is going to play a very big part, have they made there own, Or brought in a companys kit that already understands the systems

It would seem KEF have made a DSP before

Introduction to the LS50W Part 2 - The DSP

us.kef.com

Hi all. I am not an audiophile by any stretch. Can someone educate me on what makes the KEF audio option worth the investment. How is it better than standard audio? Could aftermarket be a better option, or at least comparable at a lower price point? Again, total ignorance here, but I enjoy good sound and beautiful music when not listening to an exhaust note. Thanks.

 

[andrew6382]

Hi all. I am not an audiophile by any stretch. Can someone educate me on what makes the KEF audio option worth the investment. How is it better than standard audio? Could aftermarket be a better option, or at least comparable at a lower price point? Again, total ignorance here, but I enjoy good sound and beautiful music when not listening to an exhaust note. Thanks.

Hi.... an aftermarket one could be as good, better even when you have spent 3K + on a professional install. some one once said to me its all about the effort.... the effort as in money you have to put in , and then the effort you have to put in to hear the music at its best. KEF make very good speakers. So hard to explain, how the speaker are set up , the sound stage .... Perhaps best way.... go to audio shop, ask them to demo some speaker at about £1000 on a good £2000 anp, the ask them to swap out the speakers for some at £3000, or check out YOUTUBE

 

[Jonhklee]

KEF is an excellent audio brand, with some awesome kit. First In car, so assume they will throw everything at it to get market share

 

[Tonyshepp]

Hi all. I am not an audiophile by any stretch. Can someone educate me on what makes the KEF audio option worth the investment. How is it better than standard audio? Could aftermarket be a better option, or at least comparable at a lower price point? Again, total ignorance here, but I enjoy good sound and beautiful music when not listening to an exhaust note. Thanks.

Having looked at retrofitting speakers and such like into a car and then integrating them into the main bus controllers it's much cheaper to just select the audio upgrade option.