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[Lampynoiseboy]

Having managed to avoid car audio for about 20 years, i have some questions as to how this works.....

In PA, you have the source (which is anything into a mixing desk, but for simplicity we'll call this the CD), which feeds a crossover, then an amp or 2 (again, ignoring any compressors/limiters/eqs etc), then the speakers. Obviously the cd dosen't care what it's fed into, as the impeadence of the speakers is the amplifiers problem, the cd will give line level signal at approx .775v no matter what is on the front end, be it a pair of amstrads or a stadium full of line array.

Cars on the other hand, when i last did it, had the HU with an internal amp feeding the fronts, and a line level to an amp for the rears, and obviously there are aftermarket amps designed to take speaker or "hi-level" as an input to allow the front output to be re-amped

If as i suspect, the 2013 HU has 4 speaker level outputs, for use with amps or speakers in non-Bose cars, then normally the amp would be designed specifically to take these HU speaker level outputs as it's inputs, and therefore would present a standard 4ohm load for the HU, but this being a Bose system, it presents a 2ohm load, thus asking an aftermarket HU to deliver twice what it's rated at, and cause a "thermal event", or to resemble a power sounder battery......

I can only imagine what the guys at siemens said when asked by vx for a HU with a 2ohm output....... WTF springs to mind

Can you program the 2013 HU to change the output gain structure to drive 4ohm standard, as oppose to a 2ohm Bose amp load? Or is the HU that comes with the Bose different to the standard one?

I see the only reason for all this is that Bose are well known for strange impeadences in their componants, and nobody i know has yet to work out why they don't stick to standard 4 or 8 ohms, which would've meant it didn't need re-programming or u could put whatever aftermarket HU in u liked.........even Sony. (Sorry, that was uncalled for)

alternativley, has anyone tried wiring dummy load resistors in series to bring the Bose bits up to 4ohm? Works on most other things provided the amp has enough headroom as amps normally deliver roughly half the power at 4 than they would at 2, so an aftermarket HU with 4 speaker level outputs at roughly twice what the required wattage of the Bose  should be enough to drive the speakers and dummy loads? Don't forget the heatsinks......

Clear as mud?

Sorry for the long one, I'm not arguing with the experts on here, but if you don't ask, you'll never learn... & I've used my "skills" in a variety of different trades, and vice versa- we can all learn something from someone else no matter what they do for a living!

[Andy H]

The Bose speakers are 2 ohm. I don't know what impedance the input to the Bose amp is, I assume it is much higher than 2 ohm.

The HU is programmable to drive either standard 4 ohm speakers or a Bose amp. The consensus seems to be that changing a setting in the HU from 'standard' to 'Bose' reduces the output from speaker/hi-level to some undefined lower level and brings up the word 'Bose' on the display when the unit is turned on.

Over the last 2 days I have swapped out my Bose speakers, amp and HU.

1. I changed the speakers first. Out of curiosity I tried listening to the 4ohm speakers and Bose amp and the volume level didn't seem significantly different (I left the volume control at my normal listening level & didn't try cranking it up)
2. I took the Bose amp out of circuit and fitted my link out plug. Again the volume level didn't seem much different :-/ I assume that if I had cranked it up then it would have run out of steam at a significantly reduced volume though.

I am not certain that the 'Bose' setting in the HU does anything more than display 'Bose' on the screen. Maybe it changes the output slightly to avoid ovedriving the amplifier :-/

[tunnie]

The Bose speakers

I am not certain that the 'Bose' setting in the HU does anything more than display 'Bose' on the screen. Maybe it changes the output slightly to avoid ovedriving the amplifier :-/

Think it has something to do with parcel shelf speakers which are not there on standard setup.

[Andy H]

The Bose speakers

I am not certain that the 'Bose' setting in the HU does anything more than display 'Bose' on the screen. Maybe it changes the output slightly to avoid overdriving the amplifier :-/

Think it has something to do with parcel shelf speakers which are not there on standard setup.

The big shelf speaker are sub-woofers (or subs). They are wired directly to the Bose amp whereas the wiring for the door speakers comes back to the plug in the drivers kick panel first.

I didn't notice any dedicated signal pairs for the sub-woofers (but I wasn't really looking for any).

Are you saying that the 'Bose' setting in the HU switches on a subwoofer channel?

[TheBoy]

The Bose settings on the HU do little more than adjust the levels (and probably response curve to match).  It doesn't even put the Bose logo on the display (thats a setting in the display).

The bose amp created the channels for the sub(s), the HU is purely a 4 channel unit.

[Lampynoiseboy]

Surely it must do something with the ohmage...... otherwise a 2 ohm load on what is normally a 4ohm output would cook that too, as it would do the same as an aftermarket head...?
There are a number of PA amps on the market with dip switches for impedence matching for that reason.
If it reduced the output for the Bose setup, then an AM HU would cook the amp, not the head!

[Dave DND]

The 2 Ohm impedance is between the output stages of the amp and the speakers and has nothing to do with the input side of the amp from the head unit.

When configured to BOSE, the head unit has a very narrow audio bandwidth from nothing to max volume, and operates at a different line level to the "normal" line or speaker levels - the head unit is NOT 2 Ohms.

The reason you cannot connect an aftermarket head to the BOSE amp is because of this Non standard minimalistic audio volume range that the idiots at Bose decided would be good.

 

And yes, you would cook both the amp and the head unit, as protection circuits in car are not up to much. the amp would be overdriven and when it blew, the audio stage of the head unit would be a few seconds behind it.

 

[Lampynoiseboy]

ok, see what you're saying, but I don't get what you mean by "narrow bandwith", surely it'll be 20hz-20khz at least, or else you wouldn't get full range?

Do we know what sort of line level we are talking about, in terms of volts or millivolts?

I do think idiots is a bit strong, their noise cancelling headphones are one of the best around, and the wave radio is incredible for it's size- just because they do things a little differently, doesn't make them idiots- I would think they've sold a lot more product than a lot car audio manufacturers, and been around a lot longer than some others!

[Dave DND]

ok, see what you're saying, but I don't get what you mean by "narrow bandwith", surely it'll be 20hz-20khz at least, or else you wouldn't get full range?

Do we know what sort of line level we are talking about, in terms of volts or millivolts?

I do think idiots is a bit strong, their noise cancelling headphones are one of the best around, and the wave radio is incredible for it's size- just because they do things a little differently, doesn't make them idiots- I would think they've sold a lot more product than a lot car audio manufacturers, and been around a lot longer than some others!

Ok, narrow bandwidth was probably wrong terms - difficult to explain -  say a normal volume control goes from 0>9 then BOSE would be 3>5 - there is simply very little amount of control over the volume range.

If you want to know the exact voltages we are talking about, take your meter out and measure it !!

I am not referrring to other products when I call the guys at BOSE idiots, I am referring purely to the in car stuff, BOSE have "dabbled" with it, and got it very very wrong. And no way have they even come close to selling as much as the likes of Pioneer, Kenwood, Clarion, to name but a few who have all been around a lot longer than BOSE and also produce for other markets other than in car.

 

[mrcnc53]

Has anybody else read all this and thought I should
have paid more attention at school. :-?

[Dave DND]

Has anybody else read all this and thought I should
have paid more attention at school. :-?

Not really - its all guff anyway.   

All you need to know is that BOSE is not compatable with aftermarket and newbies never read previous posts where this has all been discussed in great lengths before.

 

[Lampynoiseboy]

or nobody has bothered to really look at it from any other point of view other than what they can buy or fit from off the shelf.

If one HU can be made to supply 2 different outputs for 2 different systems, then the others can be reverse engineered to fit.

Unless all people are interested in is telling people "it can't be done" or "you've gotta spend a fortune and replace the whole system"- which is kinda false economy, because if someone can't afford to replace the whole thing then you've lost a sale, instead of looking at ways to build an interface to fit & sell them that.

As I said before, sometimes you need to look outside the the standard for an answer to a problem

[Lampynoiseboy]

Oh, and I did read the other posts, research is ALWAYS important

[VXL V6]

There's a few people on here who've probably researched the options to death to be honest. Basically we are dealing with a system thats getting on in years now and some of the options that can be taken are, at best, just a compromise.

For what it is I think the Bose system is a good option for those who want to upgrade their system in an Omega on a limited budget, however there are of course many better options out there with many more features but to do so involves a healthier budget.

Personally I prefer my Linn Sondek turntable to any MP3 player but as home hi-fi, by the nature of being seperates, will always be upgradeable without compromise (well not many compromises in comparison!) the same cannot be said for a siemens/phillips/gm 1998 glued together solution

[Martin_1962]

There's a few people on here who've probably researched the options to death to be honest. Basically we are dealing with a system thats getting on in years now and some of the options that can be taken are, at best, just a compromise.

For what it is I think the Bose system is a good option for those who want to upgrade their system in an Omega on a limited budget, however there are of course many better options out there with many more features but to do so involves a healthier budget.

Personally I prefer my Linn Sondek turntable to any MP3 player but as home hi-fi, by the nature of being seperates, will always be upgradeable without compromise (well not many compromises in comparison!) the same cannot be said for a siemens/phillips/gm 1998 glued together solution

Nice

I have an ex midi system one, not bad but not great.

Personally I like the music reproduction from my Pioneer DV575 on SACD and DVD-A