factory amp inputs?

[blackhueys]

Was wondering if I can use the left and right factory inputs to the amp as high level inputs for an aftermarket amp or not? Does anybody know or done this? thanks, scott

[kartherma]

Scott,
I am not an expert by any use of the word, but there is a posting that describes using the factory inputs in an after-market utilization.

It a lengthy posting that discusses how to install a specific set up, but the info there is applicable to your question I think...

http://www.mercurymarauder.net/reviews/showproduct.php/product/35/sort/2/cat/14/page/1

hope this helps!
be good
curt

[blackhueys]

thanks the factory amp sub setup sucks at least to me lol.

[magindat]

That post is WRONG!!!!!

Do not use rear factory speaker signal as a SUB input. It is crossed over for high pass and WILL NOT provide a subwoofer signal.

There is a mono true subwoofer signal in the harness.

Identify your +12 and -12 with a mulit meter (red and yellow, I believe). then ID the +5 trigger by probing the harness with + on meter, keeping - on meter to -12V (radio on). Other two will be +/- BALANCED signal. Wire directly to RCA plug and add splitter if necessary.

Test sound. If 'muddy', then RCA tip and sheild are backward (out of phase). Switch them.

[Pops]

Listen to Rich as he is correct.

[kartherma]

Magindat,
I must first state the most obvious...I am not an expert on this

but...

I went ahead yesterday and added a few components to my marauder.

I dropped in a 1000w Rockford Fosgate amp with two 10inch JLW6 subs and a 1Farad Cap.
I used a converter in the process also.

I took the left and right rear deck signal and sent it to the adapter and that converted it to the RCA inputs for my amp.

This set up provides PLENTY of the low signal to the sub and I have to say that from this experience I am not sure I understand what you are saying.

Bottom line, I get plenty of the lower frequency signal to my amp/sub combo. Enough so that I now have quite a job on my hands to insulate/vib-proof the entire rear of the ship.

Before we get too far, there is a built in "cross-over" in the amp that allows me to filter out the higher frequency signal.
That being said, I make a small argument that the signal to the rear deck speakers is either full range or if it is filtered as you say, it isnt filtered below about 80Hz or so.

My set up picks up signal (and makes sound) at about 60hz on the amp dial.
So, if the signal to the rear deck speakers is filtered to the mid/high range, my car is odd.

or more likely

the factor signal to the sub IS filtered to provide the sub with only the 120-ish below signal AND IS MORE APPROPRIATE for this type of set up. (basically what I am saying is I believe I am wired wrong after reading your above post, even if it is "working")

For me, it doesnt matter...After adding a set of dedicated subs, I am "happy" but not totally. A new deck and amp will be added post haste to complete the install. I will do away with the need to pull "factory signals" for my aftermarket amps.

For what it is worth...
I knew I was headed in this direction before I started. So why didnt I just do the whole thing in the first place? I guess I just had to learn it myself.

be good!
Curt

EDIT >>>>
Since I have this wired in this manner and I am thinking of doing the remainder of the install soon (but not now, maybe in a month or so) what damage can I cause to my amp/subs, anything? Do I need to go out directly and fix this or can it "limp" along until I fix it for good?

and for John, will you ship to an FPO since I am all the way on the other side of the world and these guys want an arm and a leg for a wire tie?

be good!
Curt

[Pops]

Yes I will ship to the other side of the world!

[magindat]

No doubt you WILL get signal, but is is roughly -6db at about 70. That means it diminishes 6db per octave below 70. So, at 45, 6 db less and at 30, 6 db less again. That's enough signal to amplify and can be re-equalized back out with a 45Hz boost which is built in to most amps. It is, as you said, not appropriate.

You would get a TON more signal, thus requiring less amp gain for the same output if set up as I describe. Also, distortion would be NIL since you are removing a distortion creating component (spkr/RCA adapter) from the system.

I post what I post for the edification of all and not a flame on one. I'm glad to see you took it in that way.

A new deck moots the entire arguement, as you know.

For the record, however, your assements of the -12db at about 120 down sub signal are fairly accurate. I believe the separates to be about -6db at about 70. Just enough to keep distortion-creating bass out, or about what 'bass blockers' would do in a passively crossed system.

You will not likely do any damage and it is not limping. It's just not optimal nor working as designed.

[Breadfan]

Rich is correct, low frequency to the rear deck speakers is choked. It IS there but is diminished, and drops off as frequency drops.

You CAN get a bass signal from it but it's not going to be much so your equipment will be working overtime to produce the right amount of bass that you want.

It's actually easier to simply put an RCA cable on the existing mono sub connection and run it to your new amp.

The difference will be night and day

[magindat]

You CAN get a bass signal from it but it's not going to be much so your equipment will be working overtime to produce the right amount of bass that you want.

It's actually easier to simply put an RCA cable on the existing mono sub connection and run it to your new amp.

The difference will be night and day

With his set up I don't believe the 'overtiime' will cause any long-term health issues for his particular equipment if run this way for a month or so.

if left this way permanantly, the amp will run hottter and will run with a distorted signal which will shorten it's lifespan over-all.

The system as currently set up is maybe 20% efficient. Changing it over would make it around 80-85% efficient.

You will notice a HUGE gain and cleaner bass when you switch to a new HU. BEWARE, turn amp gain down from current setting before testing on a new deck!!!

[CRUZTAKER]

This is a good thread I was redirected to for info...

I am hooking up an Infinity Bass Link in place of the OEM sub/amp.

Rich: Are you able to tell me what wires in the factory harness are what?

I have a meter, and the know how...but being American, if someone else has a short cut, I'll take it. :P

[magindat]

yeah Barry. Sent you a pm with a phone number. I'll walk you through it.