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More details for KEF Audio

digilotus

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In a prior post I promised to reach out to Lotus to get more details in relation to the KEF audio system.

Lotus have kindly shared more technical details in relation to speaker/amp placement and specifications that should help answer some of our questions.

speaker-placement.png


Some of us questioned whether there will be tweeters in the A-pillars in the KEF setup. From Lotus - "The standard base audio (128w) will become available at the start of 2023 production once we begin production of the base cars, this version of the audio system has tweeters located in the A-pillar, the KEF audio system does not use this location for the tweeters, they are located in the door as part of the Uni-Q speaker installation".

In relation to amplification, it seems that the base amp will be the DCY11 (likely the same amp as in Lynk & Co 01 as DCY11 was the model number for the 01). The Harman amp seems to be a booster amp, so it would piggy back off the DCY11 amp (rather than take pre-amp level output) for increasing power output. Power ratings here are likely to be real world power (RMS or continuous power output) and not peak power output so 340W will be plenty loud in a small cabin!

One thing I'm still confused about is what amp will drive the subwoofer. If each KEF speaker unit has two independent amplifier channels needed to drive them, then all the cabin speakers will consume 8 channels. So does the subwoofer have its own amp? Does anyone know what amplification was in place in the Evora subwoofer setup?

Based on the diagram above, ECS likely stands for Externally Coupled Subwoofer. The round hole in the chassis is therefore the open air subwoofer location.

sub-location.jpg
 
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Thanks for sharing. Gut feeling is amp set up sounds a bit of a cop out, if it is just a HK amp piggy backed on the standard (perhaps base car?) amp. Maybe it’s a 5 channel job with the 5th for the sub. This is exactly the Audison setup I just put into my Yaris and AFAIK a fairly common way of upgrading a standard system where it’s hard to get pre-out signal.

I expect it will sound great though, to be fair. I was really impressed with Audison tweets/mids upgrade plus sub.
 
The fresh air sub is this Aussie invention:

https://www.bluacs.com/

For some reason I thought it had its own amp, but on closer inspection it doesn't. Perhaps that's the job of the Class D amp (it makes no sense to amplify a signal, then amplify it again). One amp is almost certainly driving the sub, the other the surround speakers.

Not having tweeters in the A-pillars will mean the dashboard speaker is responsible for clarity and centre-staging... the sound is probably lag-adjusted by the software after bouncing off the inside of the windscreen. Should be quite a unique experience.
 
Sounds like base audio with aftermarket upgrades the way to go then so a pillar tweeters and amplifier can be upgraded. Not having high freq drivers up high just seems absurd. Will wait to hear reviews I guess.
 
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Sounds like base audio with aftermarket upgrades the way to go then so a pillar tweeters and amplifier can be upgraded. Not having drivers up high just seems absurd. Will wait to hear reviews I guess.

If the centre speaker works as expected, I think it’s preferable to a-pillar tweeters. Having off-centre tweeters on either side of your head can only give a phantom centre… which has always bugged me. No matter how you adjust them balance-wise, they can’t perform at 100% for every occupant.

With all the post-processing stuff available these days (Dirac, Audessy, etc) I’m expecting big things from KEF…
 
If the centre speaker works as expected, I think it’s preferable to a-pillar tweeters. Having off-centre tweeters on either side of your head can only give a phantom centre… which has always bugged me. No matter how you adjust them balance-wise, they can’t perform at 100% for every occupant.

With all the post-processing stuff available these days (Dirac, Audessy, etc) I’m expecting big things from KEF…
Yes but how does a single center tweeter give any side high frequency separation? Cymbals all played dead center?
 
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Yes but how does a single center tweeter give any side high frequency separation? Cymbals all played dead center?

Yep, good question. I’m guessing the Uni-Q speakers have central tweeters that angle upwards from the doors, and the “room” calibration does the rest. Speculation though…
 
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Yep, good question. I’m guessing the Uni-Q speakers have central tweeters that angle upwards from the doors, and the “room” calibration does the rest. Speculation though…
One benefit of the Uni-Q speakers is that their sound dispersion is quite wide. So in comparison to a traditional tweeter that needs to be pointed to the listener, they can be offset (within limits). You're correct that DSP equalisation will do things like boost high frequency response to offset any high frequency roll-off as a result of the Uni-Q tweeters being in the doors and not pointed directly at your ears.

The speaker units might be slightly tilted upwards too. Lotus already put the speakers as high up as they could in the doors which will help as well.
 
I think that there is no extra amp for the sub. Like I said in another tread, you don't have to use two channels per Uni-Q, it would just be the preferred choice. If you don't have enough channels, you could build a passive 2way-crossover for the Uni-Qs. I already built such hybrid systems where the woofers are actively controlled and the mid/high section passively for home use and it can work great. You could then really see the Uni-Q as one driver, couple it to the amp/DSP unit, apply equalizing, time and output correction, and the required high-pass filter. A completely active setup for the Uni-Q would of course enable the Engineers to do all this even better. If you require only 3 channels for the Uni-Qs, you could drive all the other drivers with separate channels, which makes 7 channels used in total.
Another way is to go completely active, use 6 channels for the Uni-Qs and then drive the 2 woofers parallel with one channel and the 2 drivers in the fresh air subwoofer with one channel. This is possible because low frequencies are spread omni-directional and you could therefore not tell where they come from anyways. My concern with that would be that the low end requires the most power, therefore it would be better to drive them all independently. That would also lead to more possibilities for DSP correction on the low end, but because I don't know the amp, I can't really tell if that's a problem. Maybe it has two channels that have more power than the other six, maybe it has more than enough power for each channel anyways. In terms of sound quality that's not that relevant anyways. More power just leads to a higher decibel output and has nothing to do with sound quality, except maybe for a better dynamic range due to higher power reserves.
 
I am looking at it this way - this is the first time KEF have done a car system - they won't want it to get bad reviews as it may affect their reputation. The WSJ review mentioned that it sounded great. I am sure it will
 
I am looking at it this way - this is the first time KEF have done a car system - they won't want it to get bad reviews as it may affect their reputation. The WSJ review mentioned that it sounded great. I am sure it will
Yes you wouldn't want to be KEF putting your name to something that is no better or worse than a home competitor brand of lesser value in an automotive application
 
There's also the possibility that the amp scenario is more complex, for example with some channels of the base amp driving tweeters at a lower wattage, some channels being driven by the booster amp at higher wattage, and maybe even with some channels bridged (sub). Very difficult to tell without a wiring diagram and/or some electronic analysis. OEM car audio gets very weird nowadays, sometimes the aftermarket A->B->C logic doesn't directly apply.
 
There's also the possibility that the amp scenario is more complex, for example with some channels of the base amp driving tweeters at a lower wattage, some channels being driven by the booster amp at higher wattage, and maybe even with some channels bridged (sub). Very difficult to tell without a wiring diagram and/or some electronic analysis. OEM car audio gets very weird nowadays, sometimes the aftermarket A->B->C logic doesn't directly apply.
Sure you‘re right. The only things I know from the amps are the names that were posted here and that the HK unit has 8 channels. It‘s obviously a stereo setup plus center, no multi-channel stuff. Therefore you only need two (or three - depending on the base setup) channels from the base unit that relay The signal to the booster.
 
Sure you‘re right. The only things I know from the amps are the names that were posted here and that the HK unit has 8 channels. It‘s obviously a stereo setup plus center, no multi-channel stuff. Therefore you only need two (or three - depending on the base setup) channels from the base unit that relay The signal to the booster.
They are likely doing a DSP-based, digital-domain crossover for each discrete channel. So the amp is only getting a constrained set of frequencies on each amplification channel, which maximizes its electrical performance. This is the "magic sauce" of modern powered-monitor speaker technology for home and studio applications, where amplification stages post-crossover can be optimized and phase controlled in ways that were impossible in a passive (post-amplification) crossover design. Efficiencies are much better, in-room (or in-cabin) phase-related distortion is controllable in new and better ways, and the system can be fine-tuned in the digital domain in a very rapid fashion prior to production.

Bonus, it's easier to execute as a (partner-led) development project and easier to process-engineer for manufacturing due to the reduced physical complexity and BOM count.
 
Here's a relevant view of the scenarios from a great little company called MiniDSP, they make external digital-domain crossover tech. Their products aren't directly relevant here but the diagrams 100% are.

I suspect Lotus/KEF will be leveraging the 3rd scenario, with digital crossover and split to discrete channels as part of the DSP processing.

 
Thanks for sharing. Gut feeling is amp set up sounds a bit of a cop out, if it is just a HK amp piggy backed on the standard (perhaps base car?) amp. Maybe it’s a 5 channel job with the 5th for the sub. This is exactly the Audison setup I just put into my Yaris and AFAIK a fairly common way of upgrading a standard system where it’s hard to get pre-out signal.

I expect it will sound great though, to be fair. I was really impressed with Audison tweets/mids upgrade plus sub.
1647530809318.png


Your post might as well have literally been in chinese.. haha.. there are car audio guys and then there are CAR AUDIO GUYS. But seriously, glad your expectation is that the system will be pretty good. You clearly have a great working knowledge of car audio systems.

Actually, slight edit @Pav what do you think is most likely the defining characteristic of good audio in a car of this size? I would imagine in a big SUV you need speakers, power to make it truly symphonic, but in a tight small sports car is the different? or are audio dynamics the same?
 

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