I have a mere "base" system. I changed the tweeters to Ground Zero Uranium ones, it did help . The midrange problem, well, that is hard. Anyway I thought I will add a subwoofer to the back, perhaps try to get one which can cover some of the midrange? I have a small Peerless one which may suit.

Can I easily get an audio signal from somewhere to my sub's amp?

 

Gads... Got a lot of reading and re-reading to do here! Awesome work Cambo, bringing this conversation up front and in detail!
Couple things I may have missed in the pages, and my apologies if I did

My audiophile days are long passed, but I was in the heart of it as an electronics tech back in the late 70s, and sold high end home systems for a few years after that. (I was actually in Japan when Sony released the very first CD and player...) I have hated digital audio from its introduction... sigh...

Things have certainly changed with time, so my input should be taken knowing it is outdated in areas.

You question the capacitor on the tweeter. As you found, without it you overdrive the unit. The Cap is used strictly as a high-pass filter at 6db/octave. Also with it inline, you do get 180 degrees of phase shift on the signal as it passes across it.

B&W is known for their attention to this phase difference, noting that high frequencies travel faster than low (The effect is noticed as distance increases, so the limited cabin space of a car may be moot.) Their home systems will offset the tweeter, or increase the phase shift a full 360 degrees (or more) to allow the sound to reach the listener at the correct time.
The Kevlar driver material used is extremely rigid and light. It's only real comparison is the polypropylene drivers (which were still heaver in mass than Kevlar back then), and many complained of the 'lifeless tones' from a poly. Low end qualities were where polys held their own ground, as long as you had a good amp capable of controlling the Dampening Factors needed. I don't know if DF is still an issue with today's amps, but they played heavily in controlling larger and heavier drivers in the 8" plus range in the early days of high end audio.

Paper drivers are lighter, but have their own flaws and limits.
Yamaha was first to play with paper materials in the early 80's, settling on Spruce to provide the best tonal qualities, and they were in fact very impressive compared to other high-end paper drivers.

The Car environment is harsh. Extreme heat, extreme cold, extreme moisture all attack the material regularly, unlike any home system, so poly and Kevlar are a natural choice.

Still, very interested to read your progress and the great input from others here!


BTW: The B&W in my XKR is significantly better than the Alpine in my XK in overall sound (cough cough) quality..

 

I had an 2006 XJ X358 Vanden Plas that was similarly Alpine branded. It was also terrible just as the Alpine in my Xkr is. I have come to expect this from Jaguar.

 

Clevername,
Paper is still king- particularly in car audio. Reason being what you skirted, lowest mass, it will play higher than any other material. Very important in car audio as you need a midrange that covers a lot more frequencies than home audio.

Lexus spent a lot of time developing wood cone. Its very good.

However the problem with the sound quality is not in the drivers. Its much further up the chain. Will post a video shortly that explains it.

 

Few things to keep in mind before you watch the video.
1. Your sound system wasn't designed by Alpine or B&W. It was designed by 2 companies who are competitors, Philips and Harmon. Now owned by Samsung.
2. As you can tell from the video, the problem seems to be widespread, and many new companies are working on the problem. All of them are working on the Front End! As you will see.

https://www.cnet.com/roadshow/videos...-sounds-lousy/

 

Interesting, as the Bambu system is certainly nothing new, but a resurrection of 1980's 'Dynamic Range Expansion' technology, abet modernized via computers.
My DBX 4BX breaks the audio spectrum into Highs, Mids, and Lows, and was originally dedicated to improving vinyls Dynamic Range
Base restoration was the 4th channel. (DBX created a limited number of 5BXs as well, which still draw huge dollars in the audiophile collectors market.)
Audiophiles have cursed compression from the beginning, and digital lossly encoding is the worst, as it not only compresses, but overwrites (or drops) a significant amount of music in favor of smaller file sizes. Bambu cannot 'recreate' a violin signal that is not there. It can only improve dynamic range of the cr@p at its input.

 

Yes please ignore Bambu or even Harmon's answer to this problem.
But do pay attention to the fact that the whole industry has gone after this issue.
Some amazing new things have emerged. And the industry in consolidating around one clear winner.

 

OK I finally got a chance to watch the video.

The first half of the video is addressing the problems with the source of the audio; compression, crap bit rates, and so on. And that's fair enough, but frankly that's not my problem with the system in the XKR.

The second half of the video was much more relevant, talking about staging, speaker locations, and so on. That's the bigger issue in the X150. This is the difference between the "good" systems in the XF & LR2, and the "not so good" in the XK...

In the meantime I found another MOST interface box that claims to replace the factory amp, this time providing Toslink digital output to a matched amplifier, which is all programmable. But read the fine print and it says "DOLBY DIGITAL (AC3), DTS or other proprietary multichannel sound-surround codecs cannot be decoded." so again, fixing the problem with a device like this leaves some features disabled and redundant...

Audison bit DMI Digital Interface for OEM MOST Fibre Optic Multimedia Systems | eBay

The price also sucks. £549 for the interface, another £785 for the amp...

 

How is bad compression not a problem- its very much a problem, even if you only play CDs.

Lets put a number on it, say that 50% of the poor quality can be attributed to front end and 50% to the speakers/positioning....

Speaker positioning and cabinet volume is an immovable object in the XKR.

However, improving the quality of the content will more than double the performance of even mediocre speakers and amps. Live music itself is played through atrocious quality speakers, but the front end is the real McCoy. Most crucially the complain that folks have about overall poor sound quality in the XKR can only properly be remedied by taking the tinniness out of the source (think vinyl vs CDs). The lack of midrange they hear is a combination of compression and phase shifts in the Harmon DSP.

Hopefully in a few days I will solve the compression problem. The results maybe more than enough. If not, in a few months companies will launch boxes that allow you to take the MOST signal out raw- i.e. full range. When that happens you will be able to add another small amp in the rear. That amp will have its own customizable DSP.

Beyond that one can look into neodymium drivers and shed a few pounds from their cars and take the sound further. But it wont happen by starting on the speaker end.

 

How compression affects music is really going to vary by the song and band.

Some still sound ok when I make my source a MP3 on my home system; some changing source away from MP3 there is a real difference.

I think if someone is listening to the Radio in car X, and trying to listen to the radio in their X150 they are comparing equal source to equal source.

 

Two types of compression are at play here though. If I understand correctly. Q&C is tackling 'dynamic range'. His emphasis on mid-range is unclear, as DR compression is across the entire audio spectrum. Electronically enhancing DR in mids only isn't really practical without sacrificing tonal quality across highs and lows. 'Mids only' is done with equalization.
The second compression is MP3 encoding. MP3 is MP3, which is about the worst possible method of musical data storage, even at its highest sampling rate. Half the true music is actually removed during the encoding process, and there is no way to regain it once removed. (This holds true even at the higher quality CD sampling rates, but it remains the best portable processing along with FLAC files.)

The fact todays generation accept poor quality as a 'norm' is rather sad. The same can be said about Cell phones vs the days of true copper lines. If one ever had to say "Can you hear me now?" on copper... You called the phone company to send a tech. That poor quality was totally unacceptable.

Cambo seems to be more interested in working with the existing head unit, and determining if speaker quality can be an answer, and I applaud him in his efforts. Quality speakers are essential, and can break even the best audio source into trash. But he seems to be stuck on looks of the drivers, and educated guessing, rather that approaching it with science. First thing I would recommend is getting a baseline using pink noise and a spectrum analyzer. (yesteryear, we used an actual manaquin with calibrated mikes in the ears, to adjust for driver and passenger sound and imaging.) I suspect there are still high end shops out there with similar equipment today. From there we had the ability to play with mounting locations and speaker choices to fine tune the sound as flat as possable.

What I admit lack of knowledge on is the DSP occurring prior to the output to the speakers themselves. Your source material is simple 2 channel audio, and if the amp is acting as an active or passive crossover to feed each speaker, then that should be the first thing to go. If both left and right channels can be brought out in full 20-20k, and flat, the world opens up to you.
Where/how the center channel is created is its own monster, and derived from the 2 channel source. I'm lost there, but I know it is a mathematical manipulation much like Carvers holographic generator of the early 80s. Carver however did not use a 3rd output to increase the sound stage.

As I said, I applaud both Q&C and Cambo for any efforts in tackling our problems, but truth be told, it will require 3 areas to be addressed.

Dynamic Range is probably the lesser problem, thanks to the noise floor of a car. I believe most amps today have decent dynamic headroom to accommodate some decompression without clipping, but the amp will require a decent level of 'Dampening Factor' to control cone excursion outside the intended source. (Do they even rate DF on amps any more?)

Speaker placement/replacement is the harder path, especially without equipment to test your concepts. without it, sound quality is merely subjective.

Source quality (lossly destroyed audio) is a big killer, and until the consumer is made aware of just how bad it damages sound, then poor quality will remain the standard, regardless of DR or Speakers.

 

Since I don't have quite the required knowledge to follow all this, once someone figures it out PLEASE make a post of which speakers to buy for each location.
Thanks.

 

Just wait- what is being said is that you dont need to replace the speakers- nor will it solve the problem in its entirety.

 

My radio works just fine and it reproduces great sound on the various talk programs I listen to. I must say that the AM antenna isn't as good as I would like but you can't have everything.

 

Clevername,
The DSP being used is massive amounts of compensation, equalization, to make those drivers work in that car. Thus replacement drivers would still have to go through the exiting equalization rendering them useless.

DF has increased in audio, folks still talk about it, but not necessary in car audio, its addressed through DSP- see the catch 22. In fact, the guy from THX just admitted to that in the video above. You turn up the bass, he quietly turns it down.

The compression the folks in the video and I am referring to is not the low DR. That exists in other cars too where they have good sound, its the loss of DR due to dropped-chopped bits. Its coming both from the content and then the antiquated DtoA converters in your car's audio system. For instance your car does 44kbs my phone does 512kbs. Your TV does 192kbs.

 

If I may be so inquisitive... Where did you get this data? Do you have the frequency response curves present at the outputs of the amp with everything dialed flat at the head unit?

 

We are stuck with the factory head unit, the touchscreen doesn't work with the head unit removed and the touchscreen is needed for the HVAC and other functions. Sure you can bypass the lot and put a 2nd standalone system in, kind of defeats the purpose though. And i am 100% for retaining all functionality of the existing user interface. Start adding buttons, dials, remote controls, it'll be a crappy user experience.

The speaker quality in the B&W cars is "not that bad" actually, so far as OEM car audio goes anyhow. The problem is not really the speakers themselves, it's the lack of them and what they are being driven with.

Perhaps I need to put up the wiring diagrams to show the differences between the B&W systems in the XF and the XK...

These are beautiful cars, why would we want to put something ugly in them?

As for the educated guessing, well I stand by my track record of retrofitting the factory premium/surround sound systems into more than a dozen JLR vehicles, i've listened to the crappiest base audio systems and the best factory systems JLR has to offer. I've made stuff work that no-one else could, some practicality to balance the theory is not a bad thing...

I'm all for science, but unless someone can lend me a spectrum analyzer and a spare few days in my calendar to play with it, there's only so much i can do...

I am in agreement with this, the speakers themselves aren't really the problem (apart from not enough of them), it's what lays between the speakers and the head unit, that's where this system falls over. The amplifier...

 

This is very true as the system in these cars sounds completely different when playing CDs v. Apple lossless via the iPod dock. Radio sources & MP3s, etc sound like garbage

 

Very true. The X350 used ultra lightweight genuine Alpine DD drive neodymium magnets & composite molded baskets and sounded phenomenal 13 years ago.

 

Cambo,
Apologies good sir. By 'educated guess' I attempted to bow to the fact you do have some knowledge backing your attempts.

My whole post was trying to point out that both you an Q&C are tackling our problem, but from different angles.
I live for technical data. Its just how my brain seems to be wired. (Electronics tech, Aircraft mechanic, Network administrator...)

Having been an audiophile at the time I was an electronics tech, taught me a lot about the intricacies of sound, so I am trying to follow each of your steps to see where improvement can be found.
I've also been part of several car audio builds, where we had pink noise generators and spectrum analyzer right in our store. This was the mid 80s, and I would think most high end shops have this capability running on a laptop by now (also an educated guess).

To close, I again applaud you and Q&C in your attempts!
I only wish that for the massive amount of effort you both are applying we could step away from 'subjective' to 'technical' so my brain can actually grasp and follow your paths.