sub pre amp output
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=102531
Printed Date: May 02, 2024 at 5:17 PM
Topic: sub pre amp output
Posted By: brockdog08
Subject: sub pre amp output
Date Posted: February 25, 2008 at 8:17 AM
OK, I must be totally out of this whole stereo thing from the way things use to be. I have a JVC HU with a pre-amp sub output and built in crossover...hooking this to an amp'd subwoofer, I get very little in the way of sound. It finally occured to me that the sub output of the stereo is line out, which to me means I need an amp with a line in and a line out to my amp'd subwoofer? The amp on the subwoofer will not amp this line out signal since it has no line in. Question, is this close to being on track or not? In short, is what I need a stereo, sub amp, then the amp'd subwoofer? Thank you!
Replies:
Posted By: brockdog08
Date Posted: February 25, 2008 at 9:03 AM
Let me try to explain this better...I am using a JVC HU and an oem amp'd subwoofer. The HU has a sub preamp ouput, but there is little to no audio at the subwoofer, this was also true with another amp'd subwoofer I had and a Sony HU. Same problem, different setups. Do I need to amp the output from the HU before going to the amp'd sub? I would think the amp'd subwoofer should take care of this?
Posted By: Clean Install
Date Posted: February 25, 2008 at 10:13 AM
well the vehicle would probally help... but any how... u will not need to use the sub out on a factory amp........ ------------- If we learn from each success and
each failure, then we can improve ourselves
Posted By: DYohn
Date Posted: February 25, 2008 at 10:20 AM
How have you connected a signal to your OEM subwoofer? ------------- Support the12volt.com
Posted By: brockdog08
Date Posted: February 25, 2008 at 10:30 AM
This is actually an 06 Explorer and an oem Explorer amp'd subwoofer. The HU is not the Ford unit as stated, it was a basic no frills unit. I don't think I follow your suggestion, but are you saying to just wire the sub to a left or right rear channel and not use the stereos sub output?
Posted By: brockdog08
Date Posted: February 25, 2008 at 10:40 AM
Yes, from the preamp sub output from the hu and there is audio, but very little, definitely not any amping going on. This has been the case on 3 amp'd subs and two different hu's with preamp sub outputs. I am missing a piece of this audio puzzle. I think I am needing an amp'd input to the amp'd sub, kind of like a driver. This is what I am not sure of. Basically the sub output to an amp, then to the amp'd output to the amp'd subwoofer.
Posted By: DYohn
Date Posted: February 25, 2008 at 11:11 AM
What signal from the head unit are you connecting to the OEM subwoofer amplifier, and hoe are you connecting to the OEM subwoofer amplifier? ------------- Support the12volt.com
Posted By: brockdog08
Date Posted: February 25, 2008 at 11:17 AM
I am taking the HU sub preamp output to the oem subwoofer via RCA plug terminated audio cables.
Posted By: DYohn
Date Posted: February 25, 2008 at 1:20 PM
brockdog08 wrote:
I am taking the HU sub preamp output to the oem subwoofer via RCA plug terminated audio cables.
So the OEM amplifier includes RCA inputs? That is unusual. Does it include a gain control? If so it is not set to the proper level. Have you provided power to the OEM amplifier? Also, have you turned on the sub output from the HU and set the output level? ------------- Support the12volt.com
Posted By: brockdog08
Date Posted: February 25, 2008 at 2:03 PM
I added the RCA plugs for connection ease. I have the OEM amp powered and the sub level on the hu turned up to 6, max is 8. There are no adjustments on the amp since it is a hidden behind a panl type amp. Even on the other two amp'd subwoofers I have that have RCA plugs, this symptom is identical, very low audio from the sub. Here is a silly question, are there amps made to specifically amplify sub preamp outputs such as these on headunits? Maybe these sub amps are not designed to amplify the line out and amplify an already amplified signal???
Posted By: DYohn
Date Posted: February 25, 2008 at 2:13 PM
You are right, the OEM amplifiers are generally not designed to be used with after-market head units. You cannot just use "RCA plugs for connection ease." The amplifier requires a specific level signal that is provided by the OEM head unit. This is the case for most OEM equipment. Sorry. ------------- Support the12volt.com
Posted By: brockdog08
Date Posted: February 25, 2008 at 2:23 PM
Cool, this must the case with the other amp'd subs I have then, the store bought units. They also have zero gain. It is almost like there needs to be an amp installed between the hu and the subwoofer to boost the signal into the sub, in addition to the amp on the sub. I'm baffled.....this seems to me it should be plug and play, but it isn't. I am talking about the JVC to the non oem amp'd subs, even the Sony hu before that did this.
Posted By: DYohn
Date Posted: February 25, 2008 at 2:43 PM
If you are using an after-market subwoofer WITH an amplifier - not the OEM unit - then it WILL connect to and work properly with an after-market head unit. If it's not working, then either it is installed or adjusted incorrectly. Please list make and model numbers of all the pieces of gear you want advice for. ------------- Support the12volt.com
Posted By: brockdog08
Date Posted: February 25, 2008 at 2:59 PM
Thank you, I'll have to get the list of components I am trying to use. And I agree, they should be working, but they are not. This is why I am baffled, I plug the sub preamp out to the amp'd subwoofer and really, nothing happens, adjusting the levels on the amp have an affect, but it is minimal, the rest of the stereo drowns out the sub bass.
|