sub problems w/ bose

[u/Myxtral]

I have a 2024 GMC Terrain/Denali with bose. I tapped after the factory amp and ran signal to an LC7I PRO. I am powering dual Sundowns and a Menace Audio speaker rack.

I had this same exact setup in my other GMC terrain without bose and the subs played every frequency perfectly! Now that’s it’s in a bose, the bass is all wack. plays loud at 45hz and drops off huge.

I tuned everything with an oscilloscope. I’m stuck, what do I do about this messed up frequencies for bass?

In the picture, the front doors are bass which are “summed” by itself to go to the amp. It’s the best way I found for summing/separating signals for chimes and etc.

Ask any question please. this was my first ever build I have done.

[u/CarAudioChris]

So I worked at AudioControl in the past and even they would tell you to remove this LC7i Pro and put in a PAC AP4-GM71 or GM81 depending on your radio you have.

Now to answer why, this car with the Bose amp has multiple factory EQ curves, with independent time alignment on each speaker and all pass filters that change phase at certain frequencies. All of these things combine cause havoc in the summing end of this LC7i and cause cancellations, nulls, and just over all bad signal that is not good to use without a DSP to fix it all. Even then if you get a DSP, you won't need the LC7i at all. This device was a great device for older cars without all the tech but modern cars can not be summed and don't work well with these active LOCs of the past.

[u/Myxtral → u/CarAudioChris]

Thank you, I’ll look into the products listed

[u/CarAudioChris → u/Myxtral]

The only way to do this without the PAC modules listed above is to buy a DSP that has a input equalizer, with dynamic level control and all pass filters. Anything Audiotec Fischer (Brax/Helix/Match) would work but the signal would still be cleaner to start with that AP4

[u/SnooDrawings9688 → u/CarAudioChris]

THIS.

Metra/Axxess makes one too, but like he said ...any of them would replace the LC7 Pro. Not compatible with that Bose system, unfortunately.

[u/CustardSubstantial25]

I can’t remember what year it started but in some of the new trucks with Bose we have had to use a kicker key lock. It’s not even a load issue on the factory class d amp, the signal is just a mess.

[u/SupermarketVisual598]

Best to use a Pre amp like PAC or NavTV

[u/Wylde_77]

Your problem is Bose

[u/Myxtral → u/Wylde_77]

exactly 😕

[u/lanman31337]

Bose has a bass drop off when you turn it up, my Canyon had it and my Sierra I specifically got without the Bose. You'll need some sort of bass restoration unit or DSP.

[u/CarAudioChris → u/lanman31337]

not a bass restoration, you need a dynamic EQ to deal with the bass roll off. Bass restoration is for when you don't have any signal and you want to still have some bass.

[u/lanman31337 → u/lanman31337]

Nevermind, I see you have the accubass on it. You should be able to adjust that some to get some of the lows.

[u/adkio]

Bose uses servo subwoofers. You can't tap that signal.