Fiber Optic in Car Audio?

[Montucky]

So I was having some electrical issues in my old '08 Volvo XC70 (surprise, surprise ), and was tearing the car apart trying to locate the source of the issue when I made an interesting discovery. I learned that evidently some cars use a fiber optic approach for a good portion of the audio system! I was just going in unplugging stuff when I noticed that one of the cable ends had that lovely warm beam of red light we're all familiar with. My particular car has the SUPERB Dynaudio system factory upgrade w/ the supposed but possibly 650W (130W x 5) amplifier. The audio in this car has always sounded pristine with none of the ground hum I sometimes get from my Chevy, you know where you can hear the engine revs making their way through the speakers somehow? Haha.

Anyway, whereas I might know a thing or two about home audio, I really don't know squat about CAR audio. Is fiber optic in vehicles a common thing? I guess I've just never seen it before. Makes a ton of sense in this application really, but was just wondering about it overall. Gonna do more digging online. Anybody here familiar?

 

[mtrycrafts]

Don't know if it is common and I am also surprised its use in cars. But, it seems with your report it may be common with all the electrical noise everywhere these days.

 

[Irvrobinson]

Fiber optics in cars are common, as optics are immune to interference from high voltage ignitions. Also, optical cables save weight compared to copper. Some of the articles I read discuss optical cables being most appropriate for high data rate sensors.

 

[Montucky]

Fiber optics in cars are common, as optics are immune to interference from high voltage ignitions. Also, optical cables save weight compared to copper. Some of the articles I read discuss optical cables being most appropriate for high data rate sensors.

Makes sense, but I just had no idea! Obviously nothing new since this has evidently been going on since at least the 2000's (maybe earlier?), but seems pretty cool and high tech at least to me. I don't know how this has entirely escaped me for the last couple decades.

EDIT: Guess it's been around since '98 with MB, but then it was standardized and the BMW 7-series was the first to really get it going, followed by Audi, Volvo, Porsche, etc.
https://www.laserfocusworld.com/articles/2012/06/automotive-fiber-automobiles-make-the-most-use-of-plastic-optical-fiber.html
Neat!

 

[Irvrobinson]

Makes sense, but I just had no idea! Obviously nothing new since this has evidently been going on since at least the 2000's (maybe earlier?), but seems pretty cool and high tech at least to me. I don't know how this has entirely escaped me for the last couple decades.

EDIT: Guess it's been around since '98 with MB, but then it was standardized and the BMW 7-series was the first to really get it going, followed by Audi, Volvo, Porsche, etc.
https://www.laserfocusworld.com/articles/2012/06/automotive-fiber-automobiles-make-the-most-use-of-plastic-optical-fiber.html
Neat!

One challenge for fiber optics in cars which I forgot to mention is that optical cables obviously have a much wider minimum bend radius than copper cables do. Bend radius limits the applications a bit (as the only work-around are optical repeaters), but I think still think optical cables are likely to grow in use in vehicles.

 

[everettT]

Considering the industry uses harnesses in most case I'd say that not the norm. If the seperate amp has the dsp instead of the head unit, I could possibly see it, but unless a proprietary tip used it would seem problematic.

 

[TLS Guy]

Considering the industry uses harnesses in most case I'd say that not the norm. If the seperate amp has the dsp instead of the head unit, I could possibly see it, but unless a proprietary tip used it would seem problematic.

Don't know but it probably is the norm now, as most newer vehicles use high frequency digital voltage regulators, instead of the old analog types. Those units blast RF hash in the mega Hz range, that plays havoc with audio systems. So using optical connects would make sense.

 

[Kvn_Walker]

Pretty sure that's just a Volvo thing. I had a short-lived interest in the C30 some years ago, but researched and found out that the factory radio units were difficult to impossible to upgrade due to the fiber optic cabling system. That's a deal breaker. I spend 6 or more hours a week in my car. Can't deal with a crap radio, so either it has to check off the right boxes or be easy to remove and replace with something better.

 

[Irvrobinson]

Pretty sure that's just a Volvo thing. I had a short-lived interest in the C30 some years ago, but researched and found out that the factory radio units were difficult to impossible to upgrade due to the fiber optic cabling system. That's a deal breaker. I spend 6 or more hours a week in my car. Can't deal with a crap radio, so either it has to check off the right boxes or be easy to remove and replace with something better.

Nope. BMW was first, followed by Benz, Porsche, Audi, Saab, and Volvo, using the MOST specification.

 

[TLS Guy]

Pretty sure that's just a Volvo thing. I had a short-lived interest in the C30 some years ago, but researched and found out that the factory radio units were difficult to impossible to upgrade due to the fiber optic cabling system. That's a deal breaker. I spend 6 or more hours a week in my car. Can't deal with a crap radio, so either it has to check off the right boxes or be easy to remove and replace with something better.

I doubt it. metal cables for audio are not really suitable in a car anymore. Good luck replacing the radio in a newer vehicle. First it will void the warranty, and then if you do do it, when you switch on, it will scream more noise than music at you. Fitting after market audio gear in vehicles is rapidly fading in the rear view mirror.

If you want good audio, then you need to pick the full "tricked out" versions, and you will find you get better audio than you could do, or an installer. If you buy lower trim models then you will get pretty basic audio.

 

[Kvn_Walker]

I doubt it. metal cables for audio are not really suitable in a car anymore. Good luck replacing the radio in a newer vehicle. First it will void the warranty, and then if you do do it, when you switch on, it will scream more noise than music at you. Fitting after market audio gear in vehicles is rapidly fading in the rear view mirror.

If you want good audio, then you need to pick the full "tricked out" versions, and you will find you get better audio than you could do, or an installer. If you buy lower trim models then you will get pretty basic audio.

That's kinda funny. I've done probably 20 or more radio and/or speaker upgrades on various cars in the past couple decades and never once heard anything "screaming noise" at me. In fact, never once did I or the owner of whichever car come remotely close to considering it a downgrade or a waste of money.

Yes sadly the double DIN is on the verge of extinction, but that's just a reflection of our "throwaway commodity" mindset reaching into the car industry. I can buy a 10 year old car and put in a radio that has all of today's features and tech. Buy a new car today and it's frozen in time. That might be fine for folks who just trade debt for debt every 3 years, but I can't live like that.

I've come to see over the past few years that cars in general are a waste of money. I don't buy new, and my upper ceiling is $15,000 out the door. Pay it off in 2 years, keep it till 150,000 miles, sell it and look for the next one. I've broken free of my new-car-smell addiction. Somebody else can eat the depreciation.

 

[Irvrobinson]

That's kinda funny. I've done probably 20 or more radio and/or speaker upgrades on various cars in the past couple decades and never once heard anything "screaming noise" at me. In fact, never once did I or the owner of whichever car come remotely close to considering it a downgrade or a waste of money.

Did the cars you upgraded ever have distributed amplifiers?

 

[TLS Guy]

Pretty sure that's just a Volvo thing. I had a short-lived interest in the C30 some years ago, but researched and found out that the factory radio units were difficult to impossible to upgrade due to the fiber optic cabling system. That's a deal breaker. I spend 6 or more hours a week in my car. Can't deal with a crap radio, so either it has to check off the right boxes or be easy to remove and replace with something better.

Well, you are soon in for a surprise. My car is 2011. It has a digital high frequency voltage regulator and a head unit.

Now we have had a few posts on here and we are not a car forum from people who got a loud rood noise and not much else fitting a custom audio system in cars with digital regulators.

What has driven this, is electric, rather than hydraulic power steering. These units take sudden and huge electrical loads. If they don't get it then they freeze up and have been known to cause head on crashes. I read a very interesting paper about this from BMW. Both they and Audi recalled their cars to install non pour glass matrix AGM batteries in Europe. These batteries have much better instant high current draw. They do however require a regulator that can adjust the charging voltage with the temperature, increasing it as temperature rises. If not they loose their hydrogen almost instantly if over charged.

I had a GM letter telling me that my power steering could freeze and be aware. They offered no solution. That was when I researched the issue. My dealer confirmed a couple if incidents. Now GM could not tell me if my regulator was temperature compensated. I had to do do tests to find that it was. Then I installed and AGM battery.

Now it seems to me that installing a high current draw, like a powerful audio system, in a vehicle with electric steering could actually be very dangerous. That is probably why changing the radio voids the warranty.

Certainly I strongly counsel against changing the audio system in any vehicle with a high frequency digital regulator and electric power steering. That is virtually all cars and smaller SUVs. I think full size trucks still have hydraulic power steering. Things change so fast, that I'm not even sure of that. The push to do this is to increase mpg, which it does.

On a recent trip to Europe I note the new vehicles with automatic transmission have basically a manual gear box with clutch, but operated electronically. This system has been used on the big truck rigs for sometime now. Virtually all new semi trucks come with this system now. I rode in a VW van with it, and there were issues, and my brother's Audi SUV which had it, and it changed flawlessly. Again the push for this is more mpg.

 

[Irvrobinson]

Well, you are soon in for a surprise. My car is 2011. It has a digital high frequency voltage regulator and a head unit.

What is a digital high frequency voltage regulator? Even on the newest cars with IC engines, the electrical systems run at a nominal 12 volts, and the voltage regulator is a relatively simple part that keeps the output from the alternator (or generator, as it's sometimes called) in a safe voltage range for the vehicle's electrical system (13.5v to 14.5v is a common range). Automotive electrical systems are DC, so what is a high frequency voltage regulator?

What has driven this, is electric, rather than hydraulic power steering. These units take sudden and huge electrical loads. If they don't get it then they freeze up and have been known to cause head on crashes. I read a very interesting paper about this from BMW. Both they and Audi recalled their cars to install non pour glass matrix AGM batteries in Europe. These batteries have much better instant high current draw. They do however require a regulator that can adjust the charging voltage with the temperature, increasing it as temperature rises. If not they loose their hydrogen almost instantly if over charged.

AGM batteries have better performance when deeply discharged, which makes them logical choices for vehicles with safety-related systems that need electrical power, like anti-lock brakes and electrically-assisted power steering. Battery chargers do use different strategies for AGM versus classic flooded batteries (AGM batteries like low-current slow charging, while flooded batteries like high current charging to reduce sulfur build-up), but I've never heard of a voltage regulator in a vehicle that does that. I do know that some cars, annoyingly, like BMWs, do change the charging strategy as a battery ages, but temperature variance is a concept I've never heard of. Do you have a link?

I had a GM letter telling me that my power steering could freeze and be aware. They offered no solution. That was when I researched the issue. My dealer confirmed a couple if incidents. Now GM could not tell me if my regulator was temperature compensated. I had to do do tests to find that it was. Then I installed and AGM battery.

There was an issue GM sent a letter about failure of the steering column torque sensor causing a loss of power assist, but I've never heard of or can find a link to steering "freezing". I can't believe the NTSB would approve of a steering system that can freeze over loss of assist. Can you post an image of the letter?

Now it seems to me that installing a high current draw, like a powerful audio system, in a vehicle with electric steering could actually be very dangerous. That is probably why changing the radio voids the warranty.

You know for a fact that removing the stock audio system voids the entire vehicle warranty? That seems to violate the Magnuson-Moss act.

I strongly counsel against changing the audio system in any vehicle with a high frequency digital regulator and electric power steering. That is virtually all cars and smaller SUVs. I think full size trucks still have hydraulic power steering. Things change so fast, that I'm not even sure of that. The push to do this is to increase mpg, which it does.

I think you're over-reacting, but I tend to agree that modifying the audio systems in new cars and trucks can be so complex it's not worth the trouble.

On a recent trip to Europe I note the new vehicles with automatic transmission have basically a manual gear box with clutch, but operated electronically. This system has been used on the big truck rigs for sometime now. Virtually all new semi trucks come with this system now. I rode in a VW van with it, and there were issues, and my brother's Audi SUV which had it, and it changed flawlessly. Again the push for this is more mpg.

(Warning - a classic Irv thread tangent is about to begin.) Automated single-clutch manuals, like the BMW SMG units, were poorly implemented, and are no longer used (to my knowledge). The electrically-operated manuals you're talking about are so-called dual-clutch transmissions. These operate by being essentially two transmissions in one, with even-numbered gears in one of the sub-transmissions and odd-numbers gears in the other. Only one of the two clutches is engaged at a time, but the existence of two gear rails, each with a separate clutch, allows the higher or lower gear to be "pre-selected", and a gear-change can occur as fast as one clutch can be released while the other is engaged, which is very quickly. The challenge is that the dual-clutch transmissions use friction clutches, just like manual transmissions, and it takes very sophisticated software and tuning to get them to function properly and smoothly under all circumstances. I have an Audi with a dual-clutch transmission, and frankly I like the latest planetary-gear / torque converter automatics better, at least for street use.

The problem planetary gear automatics have is heat generation under stress, and getting rid of that heat is difficult. And they aren't as instantaneous as a dual-clutch transmission, but the latest ones shift very precisely and quickly. The 8-speed automatic in our BMW X3 really impresses me. The Audi's dual-clutch implementation is sometimes annoying on starts from a stop. Too fast or too slow. The Porsche's I've driven with dual-clutch transmissions are better than the Audi, I like them better than manuals, and so are the BMW dual-clutch transmissions, but BMW seems to be switching over completely to planetary gear automatics.

The American manufacturers like planetary gear / torque converter automatics better, probably because they have better technology in that design. The latest versions of these transmissions are 9-speeds and 10-speeds, but Ford and Honda appear to be working on 11-speed models. More gears = more efficiency.

Mercedes produces an unusual transmission for some of their high-performance AMG sedans, which uses a planetary gear strategy with a wet clutch in place of a torque converter. Supposedly it's the best of both worlds, but I've never driven one.

All of these transmission are electrically operated, but they only draw significant current when changing gears, so it's not much of a safety issue.

 

[TLS Guy]

I'm on the process of moving at the moment, so I can't put my hand to the GM letter now. However the letter stated that on long straight roads, when wanting to take a curve, the electric steering could fail to react. It said you would have to muscle it through basically, but a lot of force would be required. The power steering could then over react and cause over correction. It said not to take it to a dealer. This has been a known problem on all except Chrysler, which use a hybrid system.

Audi and BMW have had a lot of trouble with this, and there were a lot of news reports sometime ago in Europe. The recall and use of AGM batteries seems to have solved the issue. The NTSB should have demanded that here, but according to my dealer they have buckled to industry pressure. My dealer in Bemidji has conformed to me that they have had customers experience this, especially the Chevy Cruze, which has been the subject of newspaper reports.

The BMW paper was interesting. They documented under test, the voltage dropping to as low as 4 volts at the power steering control unit, which rendered it temporarily inoperative. Hence the recommendation for an AGM battery.

If you go to the to this East Pen pdf you will see that AGM batteries have to have temperature compensated charging. If they don't they release their hydrogen and are ruined. So they need a lower charging voltage at lower temperatures than high, because the internal resistance of the battery goes down with temperature.

I have confirmed that my Chevy Equinox does have a temperature compensated regulator. GM could not tell me that it did, but it does.

There is much more chaos about this than there should be.

My Toyota Hybrid has an AGM battery as the starting battery in the trunk. It is expensive and has sensors attached, including a temp sensor. Only the expensive Panasonic AG battery can be used as a replacement. No others can be used. There seemed to be a shortage when I needed one, and had to drive a considerable distance to pick one up.

 

[Montucky]

Pretty sure that's just a Volvo thing. I had a short-lived interest in the C30 some years ago, but researched and found out that the factory radio units were difficult to impossible to upgrade due to the fiber optic cabling system. That's a deal breaker. I spend 6 or more hours a week in my car. Can't deal with a crap radio, so either it has to check off the right boxes or be easy to remove and replace with something better.

I hear ya, but see the TLS post below:

If you want good audio, then you need to pick the full "tricked out" versions, and you will find you get better audio than you could do, or an installer. If you buy lower trim models then you will get pretty basic audio.

Haha. Yup. I am MOST pleased with the Dynaudio setup in my Volvo. Never, ever felt the need to upgrade. Not in the slightest. As to Kvn's post about his budget window, we'll then he's in luck! A car like mine's probably not even worth what the audio upgrade option alone cost the original owner! Much like him, I too am all about (very) used cars, but by going that route, you can get a Euro model with a pretty darn nice factory system, even with 10+ year old models like mine.

 

[Montucky]

Nope. BMW was first, followed by Benz, Porsche, Audi, Saab, and Volvo, using the MOST specification.

Indeed. "MOST" is what my car has. Interesting stuff. My car may have its issues, but RF interference is not one of them. Haha.

 

[Irvrobinson]

I'm on the process of moving at the moment, so I can't put my hand to the GM letter now. However the letter stated that on long straight roads, when wanting to take a curve, the electric steering could fail to react. It said you would have to muscle it through basically, but a lot of force would be required. The power steering could then over react and cause over correction. It said not to take it to a dealer. This has been a known problem on all except Chrysler, which use a hybrid system.

Okay, higher effort sounds believable and logical; freezing doesn't.

Audi and BMW have had a lot of trouble with this, and there were a lot of news reports sometime ago in Europe. The recall and use of AGM batteries seems to have solved the issue. The NTSB should have demanded that here, but according to my dealer they have buckled to industry pressure. My dealer in Bemidji has conformed to me that they have had customers experience this, especially the Chevy Cruze, which has been the subject of newspaper reports.

The BMW paper was interesting. They documented under test, the voltage dropping to as low as 4 volts at the power steering control unit, which rendered it temporarily inoperative. Hence the recommendation for an AGM battery.

If you go to the to this East Pen pdf you will see that AGM batteries have to have temperature compensated charging. If they don't they release their hydrogen and are ruined. So they need a lower charging voltage at lower temperatures than high, because the internal resistance of the battery goes down with temperature.

I have confirmed that my Chevy Equinox does have a temperature compensated regulator. GM could not tell me that it did, but it does.

First of all, the East Pen paper deals with battery charging, not the generator-battery relationship in a vehicle. (Using the generator/alternator as a charger, like after you're getting a jump start, is actually a bad idea, and can significantly shorten the life of the generator by overheating it, especially if you use a high capacity battery.) I don't know how a charger would measure battery temperature anyway. What the East Pen paper discusses, which is the case, is that AGM batteries need a lower-current charging strategy than flooded batteries, and that if you use a flooded strategy on an AGM battery it could cause it to overheat, but that has nothing to do with a voltage regulator.

I use an Associated Equipment 9410 charger, which is designed for AGM batteries, and it uses a specific AGM strategy, and it uses a microprocessor to monitor the charging behavior, but it doesn't monitor temperature of the battery. It couldn't possibly.