Hi all. Read through many many audio threads both on and off ClubLexus but still confused and need help.

Car: 2017 IS350 non-ML

Current setup:

• Dash: Infinity Reference REF-4032
• Front and Rear: Infinity Reference 6532IX
• Sub: stock
• Amp: stock

Goal: looking to upgrade sub for bass quality(not necessarily loud thump). I need to maintain trunk space and would greatly prefer low footprint for anything I'm adding.

I purchased LC7i and a JBL Stadium 82SSI to put in the factory location. I understand LC7i/LC2i is meant to take high level output from factory amp and turn it into pre-amp signals. Originally, I thought I could do factory amp > LC7i > sub without an amp for the sub. After reading through the LC7i user guide, it says not to connect speakers directly to the LC7i output. Now to the questions:

1. Do I really need an amp between LC7i and subwoofer? will it not work at all, be perfectly fine, or still an upgrade but not full potential sort of deal?
2. With low footprint in mind, should I skip LC7i completely and install the sub without it? I bought the LC7i for channel summing thinking this would provide the best signal for the sub and avoid bass roll off
3. If I were to keep the LC7i, can I hook up the other speakers to it? (again no additional amp)
4. is the LC7i overkill and instead go with LC2i purely to add subwoofer and leave the other speakers alone?
5. if a sub amp is absolutely necessary, can I get recommendations on one with low footprint?

 

Well I’m an audio hobbyist at best but I’ll give my thoughts since nobody else is stepping up.

The lc7i is a line output converter, meant to switch high level signal to low level (preamp, rca) signal. Your factory amp > lc7i > sub seems backwards and I’m not even sure how it would do with an amplified input.
1. can’t say exactly what it’ll do, never tried it like this, but I’m guessing that even if it works it won’t be any better than stock.
2. what benefit will channel summing do for a sub? The sub channel is split before it even goes into the amp so (again, I’m guessing) the signal is probably split before it reaches the amp. Combining all the signals again after the amp seems counterproductive.
3. see 1
4. See 1
5. I just installed a JL JD500/1 in the wife’s 3IS. Accepts high level input, has low pass filter, and has 250w rms @ 4ohm which is about what you want to run if using the 82ssi in a free air application. And it has a relatively small footprint.

 

I'm currently working on a sub replacement for my car. Check out my thread if you'd like. It's going to be a slow process but it hopefully will bring back the bass it is lacking and should also work for 2014-2020 IS since the 21-23 practically have the same system.