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BMW 3-Series (E90 E92) Forum
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Is my HU digital or analog?
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04-23-2008, 11:25 AM | #23 |
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Technic,
I have question regarding the definition of balanced signals. In home high end audio, a balanced connection use three cables, while unbalanced RCA connection only two cables (just + and -). but from this thread, it seems the definition of balance signals here is actually a high level "amped" output from the HU, that can directly drive speakers.I mean does your balanced signals connection in BMW here use only two cables ? (+ and -) ? Thanks |
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04-23-2008, 11:35 AM | #24 | |
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04-23-2008, 11:44 AM | #25 |
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got it, so it basically similar to high end home audio balanced connections just without the ground cable...
and this balanced connections output is exactly the same connection/cable that connect to speaker from HU or that connect to oem amp from HU right? you mention some coding, do you mean that when it detect a hifi oem amp, the HU change the level out the "balanced output", and when it does not detect hifi oem amp, the hu coded so it give different kind of level output to directly drive the speakers??? |
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04-23-2008, 12:09 PM | #26 | |
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04-23-2008, 12:17 PM | #27 |
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ok, just one more question.
like in Audison Amp that accept speaker level input. but it does not necessarily means it accept a balanced speaker level input right? I have not do research but in unbalanced speaker level input the "-" terminal is at 0volts ... and in balanced speaker level input the "-" terminal is the opposite of the "+" volts value right? ... ie -5volts vs +5volts is the above reason why on some after market amp configuration, some people complain they do not get enough level input to drive the aftermarket amp and making them to crank up the gain on the aftermarket amp? and this is because even though their aftermarket amp accept speaker level input, but it is not a balanced speaker level input? Thanks again ps: what brand of aftermarket amp that you know/recommend (except blaupunkt) that accept balanced speaker level input... (if my assumption/understanding of balance is correct) Thanks again Technic |
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04-23-2008, 12:23 PM | #28 | |
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I do read this kind of thing a while ago... I just forget everything about it. Technics, please kindly help me... Thanks |
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04-23-2008, 12:38 PM | #29 | |
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And don't write off the Blaupunkt, I have been using an Audison SRx3, which will drive a pair of Earthquakes with 300w at 2ohm in series, and have just put the Blaupunkt into this car, it is very good. |
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04-23-2008, 01:02 PM | #30 | |
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2) Yes, that could be one of the reasons if the amp does not accept balanced inputs, although it can be worse than just signal level differences: http://e46fanatics.com/faq/stereosaga.html (good read about differential signals in BMW audio systems and aftermarket amps). 3) Alpine PDX, JL Audio, Blaupunkt THA Series (don't underestimate this line, it is pretty good). Or you can use any Audiocontrol processor and use any amp regardless of being compatible or not. |
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04-23-2008, 01:09 PM | #31 |
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Not necessarily, as balanced outputs are simply unusual in OEM and aftermarket HU's.
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04-23-2008, 01:14 PM | #32 |
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The main reason car makers choose balanced is because it picks up less noise from its surroundings, so they can use the same cheap, un-sheilded cables without picking up interference.
Running unbalanced may start to pick up whine etc., it is easy to make an output balanced so why not. |
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04-23-2008, 01:15 PM | #33 | |
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We're talking signals here, so there's no pure DC anywhere. Audio is AC with a mixture of frequencies (the sound). There may be a DC offset to the signal, but these are generally frowned upon for audio. |
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04-24-2008, 08:52 AM | #34 | |
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Question regarding Zapco
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May I ask you more question... I read your post on another thread that Zapco DC Reference model is using a Fully Differential Input Design (Symbilink).and you can connect BMW Speaker Level HU output to this input with 100ohms resistor. I do some research on those Zapco model today, and found they use a DIN style input. My question: a. since this is balanced, does that mean I put one 100ohms resistor on the "+" and one more on the "-" for each channel? ie: for front channel Left and Right means I need 4 piece of 100ohms resistor. b. What is the wattage rating needed for this resistor, so they do not blow up? c. I put the resistor in SERIES connection, right? so it add resistance to the output? d. Why you choose 100ohms value? may you provide your calculation? e. I am thinking of using some Caddock resistor to do this... f. I notice from Zapco picture that they use a 6 pin DIN connection for every 2 channel... why 6 pin? why not 4 pin, and I suspect they really follow the 6 pin of the Home Audio Balanced connection AES/EBU? Do you know the pin designation on this Zapco? g. since I will connect directly to the DIN input, I do not need to use the included symbilink inline balanced line transmitter, right? h. another question since this is 6 din pin, do I need to use 100ohms resistor for each of the pin, meaning for Left and Right front channel I need to use 6 pieces of 100ohms resistor??? I love the Zapco spec, since they include a Time Alignment, EQ, Crossover etc etc into each amp. At first I want to use the Audison LRx but I think this Zapco is much better.(the Audison VRx is also good and better then the LRx, too bad it does not support Speaker level input and does not have time alignment plus I heard that the VRx will have NEWER version because they are OLD). |
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04-24-2008, 09:11 AM | #35 |
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by the way, I e-mail Audison Tech Support today,
asking simple question whether LRx input will accept BMW Speaker Level Balanced Output... and they tell me to ask my local importer... This is funny, I mean they can just check them selves... so I e-mail them again, and said my local importer might not know this kind of thing, and rephrase the question. Now I asked them is the LRx input a Fully Balanced Differentiated Input... They have not reply to me yet... Before I was thinking if the LRx can accept "balanced" speaker level input, I will connect the BMW HU to 4 channel LRx for driving the subwoofer and rear speaker. Then since the LRx have PRE OUT RCA output, I will use it to connect to a Four Channel VRx to drive the front midrange and tweeter actively (using their builtin active crossover). I want the front channel mid and tweeter to be driven by Audison best amp possible the VRx (although their Thesis is definetely out of my budget ) and the Sub and the rear will do with their lower quality LRx... Too bad VRx definetely do not accept Speaker level input, and I heard the VRx is also a non balanced design input since they are old... I also have another idea that perhaps I just left the rear speaker powered by the BMW OEM amp... since they are just for rear fill anyway... |
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04-24-2008, 10:40 AM | #36 | |
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I don't understand why you want to not use the BLT modules included in the DC Reference amps (page 13: http://www.zapco.com/prod/DC_Ref/doc...nual_Rev_A.pdf ). It tells you right there that they not only eliminate noise but these modules are also input line drivers for better signal to noise ratio. Just solder RCA plugs in the OEM HU outputs, plug those custom RCA outputs into the BLT modules, plug that BLT module into the Zapco amp and that's it... Regardless, I don't think that you can input any wire straight or with resistors into those DIN connectors without having input issues... that's the whole idea of the BLT modules, to ease installation of any signal source. Check this installation: http://www.e90post.com/forums/showthread.php?t=66141 |
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04-24-2008, 10:49 AM | #37 |
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Hello, Technic
I do read that manual today,but isnt that BLT is actually for accepting a non differentiated RCA input and convert it to Full Symbilink differentiated input? if we connect our HU speaker level output (solder the RCA plug) and plug into that BLT input, doesn't it create problem? (I never own Zapco before ) also, if we can indeed use the BLT input, do we need to use resistor to lower the current before going into the BLT? will it clip if we direct connect it? Too bad the manual of Zapco never mention any possibility of direct speaker level input...to either BLT or the Symbilink... Thanks Technic |
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04-24-2008, 12:53 PM | #38 | |
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It will not clip because these DC Reference amps input sensitivity goes up to 10V... the OEM HU should be outputting around 5V max. You should send a PM to http://www.e90post.com/forums/member.php?u=23953 for more information about these Zapco amps installation. |
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04-24-2008, 01:12 PM | #39 | |
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Last edited by purity; 11-20-2010 at 09:26 AM.. |
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07-25-2013, 06:57 AM | #41 | |
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E90 HU digital output
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I've got BMW 3 E90 2008 (in the UK), 6 speakers with Business Satnav, iDrive, one-dvd stereo. I guess that's, unfortunately, a Base stereo system. I'd like to ask if anybody knows how to get a DIGITAL signal out of this HU... I understand that there are no digital (SPDIF/Toslink) outputs on the rear panel of the HU, but I thought there might be some ways to make digital output from it, like special harnesses or smth else. Thanks a lot in advance. FiCE. |
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07-25-2013, 07:08 AM | #42 | |
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http://www.mobridge.us/products/most-digital-pre-amp
Please search for coding your Business Nav to output Top HiFi (if possible at all). Quote:
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07-25-2013, 07:28 AM | #43 | |
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Is it possible to get digital signal straight out of my HU? Sorry, but I'm not sure I understand that. |
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07-25-2013, 07:51 AM | #44 |
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If you don't have the optical out on your head unit (some don't) then obviously there is no way to get digital out.
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