Smoking speaker!
- Thread starter steve_naive
- Start date
Pbondar said:steve_naive said:Done a bit more digging and indeed, you cannot just wire in a new head unit if you have the 10 speaker system with amp (dsp or otherwise).
Really wish I'd known this before spewing 500 quid on a stereo.
Can I really just add a couple of caps to the two tweeters? Maybe even temporarily disable the tweeters?
I did try to tell you...you need to sit down with the respective wiring diagrams of the car and the head unit and work out properly what to do..
From what you said you did, the car and the amp it wasnt going to work properly IMHO...
BMW as well as others don’t make it simple to simply unbolt one unit and replace it with a non oem part..
Didn't disagree with you, even if it looked like I did. What I meant was 'I don't understand all that'.
I'm still not sure whether the stereo is connected to the amp or not.
If not, I assume I can go down the route of adding crossovers to the tweeters. But if it is, and the amp is doing some crossover stuff of its own, then won't that affect the values of the caps I'll be wiring in?
In the meantime, I've disconnected the tweeters. Hopefully the other speakers won't explode??
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Anonymous
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Without the vin number and details of the adapter I couldn’t comment..but it would appear either the new headunit is driving the speakers directly or the headunit is overdriving the existing amp either of which could destroy tweeters
It’s relatively well know that if you overdrive an amp it starts to generate a wide and energetic set of harmonics, that energy by its very nature will burn tweeters out very quickly...
Having leant the hard way not to trust ‘standard’ bmw adapters on the E89 there’s no joy in seeing other people have issues as well..
It’s relatively well know that if you overdrive an amp it starts to generate a wide and energetic set of harmonics, that energy by its very nature will burn tweeters out very quickly...
Having leant the hard way not to trust ‘standard’ bmw adapters on the E89 there’s no joy in seeing other people have issues as well..
Pbondar said:
I've PM'd my vin.
This is the connector:
https://www.halfords.com/technology/car-audio/stereo-fitting-accessories/bmw-wiring-harness-adaptor-ct20bm02
Any help greatly appreciated!
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Anonymous
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steve_naive said:
Thnx I’ll look over this over the weekend for you..got the pm
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Anonymous
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Hello, I’ve looked at the details you sent me..you do have the 676 HiFi fitted
https://www.newtis.info/tisv2/a/en/e85-z4-3.0i-roa_200309/wiring-functional-info/body/audio-video-navigation/sound-output/llHlnwX
As a result you have the incorrect adapter when used standalone...
Your new head/amp is overdriving the old amp 676 so it’s likely that you fried the tweeters through overdriving it, causing harmonic distortion, creating n harmonics and frying the tweeters...
There isn’t a simple solution as you have a complex speaker set up as part of 676..
A possible way forward would be to insert some attenuation between the new head unit and the old amp with some inline audio attenuators aka resistors ..
https://www.amazon.co.uk/Rothwell-RCA-In-Line-Attenuators/dp/B00B7383F8
I would suggest the 15db - 20db preferably 20db ones but it’s a bit suck it and see
You would have to put these in the adapter harness in line ..
Offering advice of this nature remotely is fraught with possible errors /issues but that’s my best guess on the way forward
https://www.newtis.info/tisv2/a/en/e85-z4-3.0i-roa_200309/wiring-functional-info/body/audio-video-navigation/sound-output/llHlnwX
As a result you have the incorrect adapter when used standalone...
Your new head/amp is overdriving the old amp 676 so it’s likely that you fried the tweeters through overdriving it, causing harmonic distortion, creating n harmonics and frying the tweeters...
There isn’t a simple solution as you have a complex speaker set up as part of 676..
A possible way forward would be to insert some attenuation between the new head unit and the old amp with some inline audio attenuators aka resistors ..
https://www.amazon.co.uk/Rothwell-RCA-In-Line-Attenuators/dp/B00B7383F8
I would suggest the 15db - 20db preferably 20db ones but it’s a bit suck it and see
You would have to put these in the adapter harness in line ..
Offering advice of this nature remotely is fraught with possible errors /issues but that’s my best guess on the way forward
Pbondar said:
Makes sense, will look into it.
Thanks!
The thing is though, if you are overdriving the amp into clipping it would sound awful. If you are getting good quality sound then I doubt its clipping. A 10uf 63v capacitor in series with each tweeter is probably all you need to do to get an acceptable solution but I’m not going to keep going on about it!
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Anonymous
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ph001 said:
Hi ph001...if the output from the OE amp was broadband / flat then this is logical, in theory, the output has been processed by the amp to specifically segment the frequencies into their respective ranges for the relevant speakers..
Of course belt n braces is not bad as an engineer gaffa tape...what do you compute the cut off frequency and slope based on your suggestion?
There have been cases where harmonics have not been heard by the user but done rapid damage to tweeters due to the extended range of frequencies well above audible range..
Interestingly my after market amp has dire warnings about tweeter destruction due to either over driving the new amp and/or not having a suitable frequency roll off..
A 10uF cap will crossover a 4ohm speaker at around 4Khz and rolloff at 6db per octave.
Depends how teccy you want to get but the impedance of a tweeter is dominated by 2*pi*F*L so as the frequency rises, so does the impedance. I have never seen a tweeter damaged in practice by feeding it frequencies over 20kHz, despite the scare stories you might read on the web.
Depends how teccy you want to get but the impedance of a tweeter is dominated by 2*pi*F*L so as the frequency rises, so does the impedance. I have never seen a tweeter damaged in practice by feeding it frequencies over 20kHz, despite the scare stories you might read on the web.
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Anonymous
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ph001 said:
Thnx...still if you have a 5khz signal in harmonic distortion thats 3 harmonics..
Being a remote diagnostic on these things is never gooing to be easy..I'd love to get under the hood of the 676 amp as its used in so many configurations that it must be in part s/w driven for the widely varied uses..
Just out of interest, I was looking into the settings of my head unit today and noticed there's one named Crossover. You don't think that could offer a solution by any chance?
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Anonymous
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In a perfect world the output from the head unit should be flat and any shaping should be done by the DSP/amp...
Since you have the 676 DSP/amp that’s where BMW loads different versions of the frequency responses for each channel for each car model / speaker set up..
The issue is that you have 4 channels from the head unit then going to the 8 channels of the DSP amp...you’re not in control of that DSP/amp
So you could twiddle with it, but it’s a bodge on the back of a bad design / set up...
Your best bet , IMHO, would to throw the 676 amp and wire the speakers directly to your new head unit...but then you face some tough decisions on which speakers to use etc..
Having spent 3 months and a couple of grand I found out too late it’s not easy to simply do a part substitution of some parts..
What was the original unit you had in there?
I assume it’s the music library you want to play...is that usb / iPod cd ?
Since you have the 676 DSP/amp that’s where BMW loads different versions of the frequency responses for each channel for each car model / speaker set up..
The issue is that you have 4 channels from the head unit then going to the 8 channels of the DSP amp...you’re not in control of that DSP/amp
So you could twiddle with it, but it’s a bodge on the back of a bad design / set up...
Your best bet , IMHO, would to throw the 676 amp and wire the speakers directly to your new head unit...but then you face some tough decisions on which speakers to use etc..
Having spent 3 months and a couple of grand I found out too late it’s not easy to simply do a part substitution of some parts..
What was the original unit you had in there?
I assume it’s the music library you want to play...is that usb / iPod cd ?
Pbondar said:
I'm playing stuff from my iphone via Carplay. Spotify and whatnot.
So if I identify the correct speakers wires coming from the harness, I can just wire them directly into the new head unit?
And there would be a choice of 4 speakers from the existing 10?
Edit: I don't think I have DSP amp, just the standard one. The top Hifi is the Carver one with DSP:
https://www.zpost.com/forums/showthread.php?t=63030
