Adding subwoofer and amp

[Xrford]

Hi, I am in the middle of deciding on an amp to add to my audio system to drive a 10” subwoofer box 500w @ 2ohms. I intend to use the speaker level outputs already pre wired from the factory for the stock JBL subwoofer option. I however after doing some research on the high level inputs of most aftermarket amps they usually specify a max input voltage of 12volts. That is in the range of 36watts into 4 ohms. That seems low, but may be sufficient? Does any one know the max watts in to 4ohms or max volts the stock head unit puts out per channel? I did some research on the stock JBL subwoofer box and it has a 20volts max speaker level input, so the stock speaker level must be below 20v assuming Ineos engineered it properly. If anyone has an aftermarket amp hooked up to the speaker outputs and has no problems, I would be interested to know the make and model and its high level speaker input voltage limit. Also in my research I noticed a common theme where these aftermarket manufacturers of stereo equipment, say there is a possibility that the stock head unit will roll off the lower frequency as the volume is increased to protect the small stock speakers. They suggest using some specialized line out converters to restore the lower frequencies. Anyone notice this when upgrading their stereo with a subwoofer? Also when setting the gain on the amp they say to start off with your head unit volume at 75% of max to set your amps gain as most head units will clip above that level. This 75% seams very arbitrary and I would like to know, if anyone knows what volume level does our head unit start clipping at and if you do, how did you test it (oscilloscope, clipping meter )? They say some head units do not clip at any volume so in that case you would missing out on 25% of your volume as once you set your gain on your amp at 75% you should not go higher than that volume. My final question is has anyone cranked their stereo to the max volume and what is the max volume level of the head unit? and did it sound like it was clipping?

Thanks in advance for the help.

 

[Quartermaster]

View: https://youtu.be/hLGfTj5Ja-E?si=32GYi8vfE4rFr_Px


In this video he maesures no clipping at full power, 5 watts/ ch into 4 ohms. He does not mention subwoofer prewiring - do you know, where it is located?

 

[RobP]

Here's a thread on my sub/amp install with a link to the amp specs:

Added a 12" sub to my "premium" sound

As has been discussed, the premium sound option in the US is nothing more than a 6"x8" sub/amp combo mounted under the rear passenger seat. It's the weakest part of the audio system (to my ears) and I miss the thump of a real subwoofer. I enjoy doing my own installations and this was one was...

www.theineosforum.com

 

[Xrford]

View: https://youtu.be/hLGfTj5Ja-E?si=32GYi8vfE4rFr_Px


In this video he maesures no clipping at full power, 5 watts/ ch into 4 ohms. He does not mention subwoofer prewiring - do you know, where it is located?

Wow thank you @Quartermaster. This video answered all my questions, it reinforces my faith in the German technicians; taking measurements of everything to do with the stereo before doing any modifications.

Summary see around 25 minute mark:

• Max volume level on the head unit 14
• At max volume level there is negligible distortion emitted by the head unit at 100HZ. No clipping seen on oscilloscope
• Head unit puts out 5.76watts @4ohms per channel at max volume at 100HZ. This is just under 5volts
• Head unit speaker output signal is linear form 20-20khz. No roll off of bass, no dsp interference.

What this means is any amp that has high level input capable of accepting up to 7volt should work. No need for any special line out converters needed to restore the bass signal. When setting the gain on your amp you should be able to adjust it while your head unit is at full volume as the head unit does not clip at full volume(see YouTube videos Adjust gain using multimeter ). The only not so good news is how little watts the stock head unit outputs, you will need all of that 5.76 watts to get some high volumes out of your system.

 

[GN4HIR]

Lord, give me the strength not to launch into another audio build. You know I've been surviving on OEM sound for 4 or more vehicles. Somewhere here in the garage I have an Audison Bit One and a JL HD900/5 wrapped in plastic for long term storage. Wish Xrford hadn't posted that the headunit is linear. Of course, I don't know if I could survive the BONG for low gas backed by 900 watts.

 

[Xrford]

@Quartermaster i forgot to answer your question. If you have a 2024 or newer model then you should find the stock sub output connector on the passenger side (right side) of the center tunnel under the backseat, wrapped in foam and taped to the main wiring harness with white tape. Mine was between the auxiliary battery and the centre tunnel. Here are some images that may help that I found on other threads on this forum.


;

 

[Quartermaster]

@Xrford found it, great, thank you!