specifications for speakers?

[tim eh?]

the short: I need specs (Watts and ohms) on the factory speakers so as I can make crossovers.


the long: I decided to finally do the factory amp bypass.

So I did the soldering but I must have botched it somewhere. Looks ...errr... ok .... i think ... :D (black is + here btw!!!!!)

http://www.bimmernut.com/forum/attachment.php?attachmentid=6633&stc=1&d=1237242683

So anyway there is something badass going on when I turn the head unit on... definitely a bad circuit as the HU keeps turning itself on and off and there is a nasty click in the speakers.

HU works perfect if I disconnect the speakers... so I hooked up a spare pair and the HU works fine with those and it indicates that my wiring is good (I am connecting the +s at the amp plug and I ran new -s from the HU to the trunk which took forfrigginever).

I have taken the amp apart and resoldered with the same result. No blown fuses, no evidence of a burnout in the amp.


SO, I'd like to make external crossovers for the existing speakers... I don't want to replace all the speakers (yet). I haven't done this before but I understand the circuitry, I think I just need the numbers (Watts and ohms) from the factory speakers but I'll take whatever pointers anyone has... any help?

edit: btw the HU is a 4x40W JVC... worked perfect running through amp.

edit: found this - rear speakers low= 40W/4ohms tweeter= 40W/8ohms

edit: It is occurring to me that the trouble may be with the speaker grounds as it is an active crossover with shared grounds... i think...
am i talking to myself? i think i am... tbc...

[pingu]

If the HU keeps turning itself on and off then I wonder if maybe some mis-wiring is upsetting the amp which then turns the HU on and off. Given that the HU works perfectly if you disconnect the speakers, I'd maybe try connecting the tweeters and woofers etc one at a time until you can work out exactly what is causing the problem.

Unless I'm mis-understanding you, I think you're under-estimating the complexity of a cross-over. The watts and ohms of the factory speakers are almost irrelevant to the cross-over (OK, it'll effect the power rating but not the values of the cross-over components). What does matter is the frequency at which the woofer and tweeter (and mid-range?) need to be crossed over, which will determine the values of the inductors and capacitors.

I see from your edit that there is possibly something to do with shared grounds and I reckon that your time would probably be better spent investigating this rather than trying to make a cross-over from scratch. (I have built amplifiers, loudspeakers and CD players in the past and I would always try to avoid re-building a cross-over from scratch.)

Anyway, good luck. Let me know if you have any queries.

[tim eh?]

Thanks - I think you are right, I will restore factory grounds first and see...

I was doing some reading here... I guess it's just impedance you need not watts.

http://www.diyaudioandvideo.com/FAQ/XOver/

the parts list calculator is neat.

http://www.bimmernut.com/forum/attachment.php?attachmentid=6635&stc=1&d=1237259224

http://www.bimmernut.com/forum/attachment.php?attachmentid=6636&stc=1&d=1237259224

[tim eh?]

ok so there is no change... bummer.
but at least it works if I don't run the speakers through the amp at all... must fix...

[ArnZ!]

im interested also about what ohms the speakers are.

Cuz atm im only using two channels from my 4 channel HU. But all the speakers run off it.... Ive also done the amp bypasss succesfully. Thing is that i want to full utilise the 4 channel power.

[tim eh?]

I measured the resistance with a multimeter through the amp plug. Results...

Rear Woofer = 4.0 ohms
Rear Tweeter = 6.5

Front woofer =4.0 ohms
Front MR = 4.7
Front tweeter = 6.6

tbc...

[ArnZ!]

are u able to measure the ohms needed to go into the amp box (by amp box i mean cross over box after gutting the amp)

[tim eh?]

are u able to measure the ohms needed to go into the amp box (by amp box i mean cross over box after gutting the amp)

i'm afraid i can't, that is the part that is busted.

[Ross]

Just curious Tim. Why not use the factory crossovers with the factory speakers?

[tim eh?]

Just curious Tim. Why not use the factory crossovers with the factory speakers?

That's what I tried to do, but I screwed something up. Actually I took the amp in to a pro yesterday, it would solve a lot if it was just my lousy soldering and he could do it properly for me, that would be so sweet.

[BMWDriver]

How's that coming out? I'm curious to do the same. I can only crank my volume so far before I get distortions with my aftermarket.

[tim eh?]

How's that coming out? I'm curious to do the same. I can only crank my volume so far before I get distortions with my aftermarket.

amp is still in shop... no stereo = :(

don't want to rush ma man ... but if he can fix mine he can fix yours, unless you ****ed yours up like me. his shop is around the corner from me.

i would suggest you wait until

a) mine works
b) we see the bill...

i'll keep you posted... anyone else? maybe we can get a bulk order going...

[bloodyvsunday]

well considering, from what i understand from reading..
your installing aftermarket amp?

If your getting a lil short momentarily due to the speakers..
try getting a say...6 foot speaker wire cable... finding all the due points of the speakers, and grounding them yourself..
or better yet..
only hook one speaker up at a time to break down WHICH speaker it is?

If im far off the topic, my apologies..
Not much sleep lately. started classes this week, tired as hell.

But anywho, after resolving which speaker, im sure you can go from there?

I mean cracking normally indicates a overpowered..or underpowered speaker...duh lol sry for stating the obvious..
I have a 1200 watt profile amp..of course..only to a sub >:}
Gotta love feeling the music a lil bit more with a little bass.

But from what i can conclude...at first i went through the factory amp and did the rewiring, and turned out fine...
however i decided to avoid that...dont ask me why..
just a weird spazm of mine?

[tim eh?]

i am so frustrated.

just spent a while at this repair shop and it took everything i had to keep it all bottled up inside and walk out of there calmly...

basically i have just been told that i never had my stereo hooked up to the amp (which i did) and if i did it never worked (it did) because the input schematic i gave him was all wrong (it isn't). and if i did hear sound (i did)then there is no way the balance and fade worked (they did) because the amp is not designed that way (it is)!!!!!!!

anyway, since my amp is all frigged now anyway i am going to try and build crossovers out of its guts and just hope they work at the reasonable frequencies, if not i guess i'll go looking for an active crossover setup for the fronts at least.

i'll let y'all know...



If im far off the topic, my apologies..

no problem, thanks for trying :)

[ladiesman217]

some people are just parts swappers, not repair people.
he is the later. Congrats on the elegant fix btw. :)
you showed him!