Alfa Romeo Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
1,374 Posts
Discussion Starter #1
Hi all, quick question about front components in my 1999 156;

I'm replacing the non-Bose with affinity, is there a crossover behind the card or are both cables to tweeter and woofer straight from head unit? (So when I fit affinity components can I just take 1 of the cables and put it as input to affinity crossover?)

Many thanks!
 

·
AO Silver Member, 155 Lounge Winner 09
Joined
·
7,713 Posts
(So when I fit affinity components can I just take 1 of the cables and put it as input to affinity crossover?)
^^^ that.

Wires run from the headunit into the door, then divide into two. One branch to the woofer, operating 'full range' (no crossover involved), the other to the tweeter, which has a tiny inbuilt capacitor which functions as a highpass filter.

You can connect either branch to your (?) Infinity crossover.

:)
 

·
Registered
Joined
·
1,374 Posts
Discussion Starter #3
^^^ that.

Wires run from the headunit into the door, then divide into two. One branch to the woofer, operating 'full range' (no crossover involved), the other to the tweeter, which has a tiny inbuilt capacitor which functions as a highpass filter.

You can connect either branch to your (?) Infinity crossover.

:)
Cheers, suspected this may be the case. Easy easy easy install!

But- does this mean that effectively the original front speakers are 2 ohm? And being driven by 4 ohm head unit?
 

·
Premium Member
Joined
·
7,698 Posts
Cheers, suspected this may be the case. Easy easy easy install!

But- does this mean that effectively the original front speakers are 2 ohm? And being driven by 4 ohm head unit?
Bose system speakers are 2 ohms, standard (non-Bose) are 4 ohms
 

·
Registered
Joined
·
1,374 Posts
Discussion Starter #5
Bose system speakers are 2 ohms, standard (non-Bose) are 4 ohms
Indeed. But if you split the output from a 4 ohm head unit in parallel, to 2x 4 ohm speakers, then the resistance faced by the signal is halved. Hence it becomes a 2 ohm speaker.
 

·
Premium Member
Joined
·
7,698 Posts
Indeed. But if you split the output from a 4 ohm head unit in parallel, to 2x 4 ohm speakers, then the resistance faced by the signal is halved. Hence it becomes a 2 ohm speaker.
not really, as you're talking ac current here (including the serial capacitor on the tweeter causing very high dc resistance ).... ;)
 

·
Registered
Joined
·
1,374 Posts
Discussion Starter #7
not really, as you're talking ac current here (including the serial capacitor on the tweeter causing very high dc resistance ).... ;)
Been a while since I did a level physics. Is resistance not calculated the same, as in parallel divides and in line adds? If you place 2 4 ohm speakers you create an 8 ohm speaker. If you place 2 in parallel you create a 2 ohm speaker? Out of interest what is the resistance of the factory tweeter?
 

·
Premium Member
Joined
·
7,698 Posts
speaking of dc resistance, yes. However, a speaker is not a dc resistance but an impedance.
In addition, a capacitor in series with a tweeter will create a very high dc resistance...
 
1 - 8 of 8 Posts
Top