Where is the best place to tap into the sub signal in the B7 A4/S4/RS4?
05-28-2007, 11:46 AM
#1
AudiWorld Super User
Thread Starter
Where is the best place to tap into the sub signal in the B7 A4/S4/RS4?
I'm upgrading the stock sub to a better aftermarket one and am building the box and attempting to do the install myself. I am having a hard time finding the wires that feed the stock sub so I can tap into these as a signal source. Everything is SO tucked away and difficult to access. Any advice?
05-30-2007, 12:31 PM
#2
Member
Join Date: Sep 2004
Posts: 1,114
Likes: 0
Received 0 Likes
on
0 Posts
I would get a harness from Teddy B so you can get a nice clean low level input
The signal from the stock sub will be very processed and will probably make your aftermarket sub sound awful.
05-31-2007, 01:18 AM
#5
AudiWorld Super User
Thread Starter
Will this product work??
Line output converter with ground loop isolation.<ul><li><a href="http://www.pac-audio.com/products/productsCatagory.asp?mmSearch=Line+Output+Converte rs">click here</a></li></ul>
05-31-2007, 07:03 AM
#6
Junior Member
Join Date: Apr 2006
Posts: 1,154
Likes: 0
Received 0 Likes
on
0 Posts
Line output converters take speaker level to preamp level.
So either grab the sub wires, at which point you will need an LOC either in the amp or external to the amp (but NOT need the GLI portion, since subs don't play engine noise as a rule, and since tapping the output side of the amp doesn't create a ground loop on the input side of the amp), or you can tap the preamp signal between the HU and the amp, which is what he's talking about.
Doing that often creates a ground loop between the OEM HU and the OEM amp and results in the OEM tweeters playing RPM-related background noise, until you get rid of the ground loop with a ground-loop isolator.
GLIs case sound degradataion and are usually to be avoided, but in the last year a few guys have had this problem tapping on the input side of the amp ahd solved it this way.
The above post about processing is meant well but lacks enough data behind it. The Bose-mode HU output is flat and unprocessed and the Bose amp output is processed, but not in such a way that it will hurt your sound of the sub dramatically. I wouldn't do it, but I wouldn't keep the rest of the Bose system either... and I'd do it for you as a client, just not for me in my car, cause I'm **** that way.
But non-Bose HUs have the processing in the signal on its way out - too late - and the bass goes away as volume increases - which does seriously jack with your sub's sound. I wouldn't add a sub to a non-Bose system without some significant change.
Doing that often creates a ground loop between the OEM HU and the OEM amp and results in the OEM tweeters playing RPM-related background noise, until you get rid of the ground loop with a ground-loop isolator.
GLIs case sound degradataion and are usually to be avoided, but in the last year a few guys have had this problem tapping on the input side of the amp ahd solved it this way.
The above post about processing is meant well but lacks enough data behind it. The Bose-mode HU output is flat and unprocessed and the Bose amp output is processed, but not in such a way that it will hurt your sound of the sub dramatically. I wouldn't do it, but I wouldn't keep the rest of the Bose system either... and I'd do it for you as a client, just not for me in my car, cause I'm **** that way.
But non-Bose HUs have the processing in the signal on its way out - too late - and the bass goes away as volume increases - which does seriously jack with your sub's sound. I wouldn't add a sub to a non-Bose system without some significant change.
05-31-2007, 09:34 AM
#7
AudiWorld Super User
Thread Starter
So which, if either, would yield a better result?........
1. Feeding the stock sub wires directly to the high level inputs on the new sub amp or....
2. Using a line output converter and using the low level inputs?
Thanks!!!
2. Using a line output converter and using the low level inputs?
Thanks!!!
Trending Topics
06-01-2007, 07:19 AM
#8
Junior Member
Join Date: Apr 2006
Posts: 1,154
Likes: 0
Received 0 Likes
on
0 Posts
There is no spoon...
Using the speaker outputs will retain the Bose processing, which I find acceptable. It is not optimum in that:
- the LOC you use may have a non-flat freq response in the low end, and that may change your sound. If your amp will take speaker level inpus directly then this is not an issue (those amps lack transformers in the LOC or lack an LOC entirely).
- The Bose system EQs the bass.
...but it is good enough IMPO for a guy who is keeping his Bose system. If you had audiophile sound out of your woofer and Bose sound out of the rest of it...well, should that be my target? Interesting question, my answer's no.
If you use the preamp outs you eliminate the Bose processing but you will probably need a ground-loop isolator to prevent RPM whine. Those also have the same sonic issues as LOCs unless you spend +$100 on one.
I'd rather have no noise issues and not worry about the last few points on the sub SQ.
- the LOC you use may have a non-flat freq response in the low end, and that may change your sound. If your amp will take speaker level inpus directly then this is not an issue (those amps lack transformers in the LOC or lack an LOC entirely).
- The Bose system EQs the bass.
...but it is good enough IMPO for a guy who is keeping his Bose system. If you had audiophile sound out of your woofer and Bose sound out of the rest of it...well, should that be my target? Interesting question, my answer's no.
If you use the preamp outs you eliminate the Bose processing but you will probably need a ground-loop isolator to prevent RPM whine. Those also have the same sonic issues as LOCs unless you spend +$100 on one.
I'd rather have no noise issues and not worry about the last few points on the sub SQ.
06-01-2007, 01:50 PM
#9
AudiWorld Super User
Thread Starter
Great. Thanks for the detailed answers! Only one thing left....
Is there a place I can actually access the wires feeding the stock sub without ripping apart my whole trunk?