I need to make some crossovers for the stock 10 speaker set-up.
Does anyone know the response frequency for each speaker? I tried using some generic crossovers and they put out too much bass in the midranges.
BTW, I already know they are all 4 ohm besides the front tweeters which are 8 ohm.
Thanks,
-David
Anyone know the output of the stock amps or the power ratings for these speakers as well?
So wiring the mid-bass and mid-range in series, parallel with the tweeter would give 4 ohms.
Throw in a passive crossover network and you could power them with a small external amp?Code:-------- | | W | | T M | | | --------
phear my ascii art skills.
Passive crossovers don't *have* to be wired like a set of components
A 20mfd Cap inline with the 8ohm tweet will give a highpass of 1000hz
A 1.3mh inductor combined with a 200uf cap inline with the 8 ohm woofer/mid will pass signals between 100hz and 1000hz
What you lose by wiring them in series and parralel is the ability to do a 3-way cross where you bandpass the woofer and the mid at different points. Unfortunately this is the only way to get 4 ohms from the setup.Code:---------- | | 1.3mh 20uf | | W | | T M | | | 200uf | | | ----------
You could wire them all in parallel, and cross each over but you would end up with a 1.67 ohm load, which in my case would be too low.
This would be a 3 way passive wired in parrallel (1.67ohm). If you have an amp that is 1 ohm stable, and 40ish watts@ 1 ohm you could do this.
I'm not 100% sure this would work, since there is a 4 ohm path, the 8 ohm tweeter may never see any voltage. (see my notes at the bottom)Code:-------------------- | | | 1.3mh .64mh 20uf | | | W M T | | | 400uf 80uf | | | | --------------------
The crossover points here are
100-500 (1.3mh passes below 500, 400uf passes above 100 (for 4 ohm))
500-1000 (.64mh passes below 1000, 80uf passes above 500 (for 4 ohm))
1000 (20uf passes above 1000for an 8 ohm load)
The values change for the woofer/mids becuase the impedence changed, there are now 2 seperate 4 ohm loads instead of 1 combined 8 ohm load.
I rounded some of the cap and inductor values.
These are first order passive crossovers. 6db/octave http://www.bcae1.com/passxovr.htm
Higher order crossovers with more aggressive roll offs (12/18/24) are possible with the same types of components. http://www.bcae1.com/xoorder.htm
You want non-polar caps for all audio signal use.
Technically speaking you can wire a 4ohm 50watt non-inductive(don't want it to act like a low pass) power resistor inline with the woofer and the mid to bring them up to 8 ohm loads (they would need their own fans probably), change the inductors and caps, and give a 2.67 ohm load to the Amp and equal 8 ohm paths for the circuit.
Last edited by Mjollnir; 05-03-2006 at 01:57 PM.
ive been wondering this forever....
Bookmarked...
These are NOT the frequencies.
I was using those as examples of how to build a passive crossover without using 3 amp outputs.
I'm not sure how to determine the stock crossover frequencies without putting it on a scope. Let me get the etk loaded and see if it has the info.
I didn't say 3 amp outputs, I just said use one amp output with a crossover. I have used one and hooked up the 4ohm woofer and midrange and 8ohm tweeter and it was still 4ohm in the input, God blesses the crossovers. Of course the cut points were screwed up but it still worked without killing my stereo (it was wired directly to it).
I need to know the frequencies for the stock speakers in order to make the right crossover
OK.
You fried your stock amp right?
Is it out of the car?
I found some useful information (not the answer, but the path to the answer).
from http://66.249.93.104/search?q=cache:...s&ct=clnk&cd=2 not that it matters.There is no crossover in the BMW head unit!(at least in the USA).
The crossover is in the BMW amp. It is a passive crossover at the output
of the four-channel amp. There is nothing high-tech about this, it's a
regular old passive crossover made from run-of-the-mill capacitors and
inductors. They are just located inside the amp chassis instead of
between the amp and the loudspeakers. And no, it's not ten 25W channels.
The amp is four channel, and by Hi-Fi standards puts out 15W/channel.
Yep, that's all folks. The crossover for each corner of the car is at
the output of each channel, and divides the spectrum appropriately for
the drivers on that channel. The only problem with this set-up is that
you don't have a powered full range output to drive aftermarket speakers
that you can get to with without tearing the amp apart and making an
internal connection. This pretty much forces you to replace the amp as
part of a speaker replacement just so you can get a full-range signal.
Open up your amp, take hi res pics of the circuit board. I'll ask you to look at a few things more closely after I see a pic of it. Basically, they are using passive crossovers like I described earlier, if we can find the values of the caps, inductors, and resistors we should be able to work backwards to the crossover frequencies., the front stage is only 2 channels, right and left that are split into a crossover inside the amp casing, think of a 3 way component crossover, 1 in 3 outs, its just built into the amp case, and will be very close if not the last thing before the actual output connectors.
If you can't take pics for some reason I can look at mine next week, I just won't have time to get it out before then.
As far as I have checked, it's a real 10 channel amplifier. It has five TDA7374B as you can see, each one is a dual amplifier.
http://pdf1.alldatasheet.com/datashe.../datasheet.pdf
Why do you want to go through so much trouble to keep the stock speakers?
I'll take your word for it, I could not get alldata to come up. It would not make sense to have 5 audio amps on a 4 channel system. I love misinformation on the internetOriginally Posted by Daved
Last edited by Mjollnir; 05-03-2006 at 09:54 AM.
10W @ .5%THD
21W @ 10% THD - Yuck! Measured at 1Khz - not 20-20K
No Beuno!
http://www.datasheetcatalog.com/data...DA7374BV.shtml
Matt I
BMWCCA #353696
It doesn't matter, its actually better that way since the amp isn't amplifying the signals it is going to filter, less waste.
Yeah, I have been looking all morning.
The little brown and yellow boxes are thin film caps, I have only been able to find the specs on a few of them.
15nJ100 .015UF 100v
2N2J400 .0022UF 400v 5%
From an analysis of other part numbers I have found with the same number format we get:
15 = value in nanofarads (nF)
n = decimal? unsure, however 2n2 is 2.2nF
j = 5%, unsure (this is a standard rating for caps, appears to apply here)
100 = rated voltage
(for example 47nJ500 is 47nf 500v 5% and 1nJ400 is 1uf 500v 5%, these are actual caps, not deciphered)
So that gives us a few known values
.015uf
.0022uf
.027uf (27nJ100)
.082uf (82nJ63)
.0015uf (1n5J100)
What I don't know
6*1j50
6*10nJ100
Red items (can't read anything on them small ones)
Blue/gray items (cant read any of the ink)
I was not able to find any datasheets for the Vogt components.
Working on it.
Any traces on the back side of the board?
This is awesome.
If we find this information...we can use it for all the n00bs who just want to replace their factory speakers and not do a whole new system.
I f you buy aftermarket speakers with broader frequency ranges than those of the stock, you can replace them and the factory built in crossovers will still be effective.
Sticky this when we find it. Definately useful links quality for eric's thread.
Me too, the wife will kill me if I buy new components. My amp isn't dead (yet), but since I am using my 5v RCA's from the deck, its not quite right even though it works.Originally Posted by Daved
Can I get a pic of the backside of the board?
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