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Just picked up a new IS. I'm looking for ways to do an aftermarket stereo in it. My goal is to do a 3-way active up front and use the stock sub for a little bass fill. I'm not a bass head and I'm too old to listen to things loud, so my main goal is clarity, flat response, and to control directivity.
Knowing that replacing the HU is next to impossible, I moved to investigating the strategy of utilizing the high outputs of the stock amplifier to be placed through a DSP and to aftermarket amplifiers. I've seen several members do something similar.
Firstly, I needed to see what kind of signal I was dealing with. I was hoping for a flat frequency response out of the door speaker. I installed a quick disconnect between the amp and the left driver's door speaker. I then hooked it up to my RTA, and here's the result.
Front left door output of a 2016 IS 350 (non Levinson stereo)
Absolutely terrible. The green read is from my reference amplifier (nothing fancy). It is +/- 2.5db pretty much from end to end.
The pink read is from left door output of the stock amplifier in the car. I think the readings speak for themselves with a swing of 20db between midrange and highs. Please note that I am not measuring the speaker, I am measuring the amplifier output.
This is going to be much more challenging than I hoped. I'll keep on updating this thread as I move through testing more amp outputs. I'm expecting to have to sum the front door, dash, and sub channels in order to get anything somewhat flat. bummer...
And here's the dash speaker. Kudos to Lexus for doing an active crossover setup, but it makes it much harder on me. I'm going to have to sum these channels. I'll try and measure the sub tomorrow.
Front left dash output of a 2016 IS 350 (non Levinson stereo)
Have you read Percy's review on the Mark Levinson version? Interesting perspective from an audiophile - not being someone that can truly tell the difference, it sounds okay to me.
Have you read Percy's review on the Mark Levinson version? Interesting perspective from an audiophile - not being someone that can truly tell the difference, it sounds okay to me.
Mariners!
I didn't check out the ML version in depth really. I was dead set on getting a model without nav though and I don't think there was any models with ML and no nav.
The stock system doesn't sound bad. It's actually much better than the Harman Kardon system in the 3 series. Imaging is great when faded forward a couple clicks to the front, and the sound is really flat when the bass is taken down a couple clicks as well. I just like tinkering - lol.
I didn't check out the ML version in depth really. I was dead set on getting a model without nav though and I don't think there was any models with ML and no nav.
The stock system doesn't sound bad. It's actually much better than the Harman Kardon system in the 3 series. Imaging is great when faded forward a couple clicks to the front, and the sound is really flat when the bass is taken down a couple clicks as well. I just like tinkering - lol.
I have the ML version, and so far so good - but again, haven't really tinkered with it aside from turning up bass and treble a couple of clicks, and also coming from my Subaru, anything is going to sound better.
i have the ml version, and so far so good - but again, haven't really tinkered with it aside from turning up bass and treble a couple of clicks, and also coming from my subaru, anything is going to sound better.
Here's the sub output of the amplifier. Observation wise, it extends reaaaaly low. I would have expected them to use a more aggressive subsonic (highpass) filter to avoid rattles/blowing the sub. I'm probably going to use a really steep slope (48db) at 35hz to start with.
Looks like they have a decently steep low pass slope (maybe 24db) starting at ~ 100hz. Very decent choice not allowing the sub to extend too far into the midrange. Also, I don't really see any "trickery" like a big bump at ~150hz to give an illusion of extra bass, perhaps the driver itself is already doing that.
This is what you guys should be tapping into for adding an aftermarket sub, not the rears. You wouldn't even have to adjust crossover points really, just set gains, and you'd be in a good place for most popular "tastes" of subwoofer-ness. I personally would have the sub start rolling off at 60-80hz, but most people like a bit of extra boom that can be had with this stock output.
I'm looking into the JL Fix 82 for summing. Still undecided on DSP. Let me know if you guys have any questions.
Subwoofer output of a 2016 IS 350 (non Levinson stereo)
Here's the right rear door. Some heavy EQ'ing going on here for sure. Big peak at ~ 4khz which is a bit scary since most 6.5" speakers will start ringing around there. Looks like they completely ignored 5khz and up in terms of correction since a 6.5" won't play well that high no matter how much EQ'ing you do.
As far as the low end, I don't know how in the world people are recommending tapping into this output for a subwoofer. Output under 100hz is down 15db from the peak output of this channel, and starts rolling off immediately. This is not a good candidate for subwoofer output.
As far as summing overall, this is the "widest" channel available in the car. I'm not sure if the rears are TA'ed, but as of this moment, I am thinking of summing the subwoofer channel, the dash channels (not center), and these rear door channels. I'll have to think about it some more and make a follow up post.
Rear left door output of a 2016 IS 350 (non Levinson stereo)
Now that I've measured all the channels' frequency response at a baseline volume, I wanted to make sure that the frequency response did not change with volume settings in the car. Many manufacturers will roll off bass/highs as the volume **** is cranked in order to not sound like crap.
There really isn't a way to combat a system that has volume dependent EQ'ing. You basically either have to live with the constantly varying frequency response, or set the head unit volume at a specific # and leave it there forever and use an outboard volume **** (and lose steering wheel volume control in the process).
I'm glad to say that thus far, I haven't found any heavy indication of volume dependent EQ'ing.
In the graph below, it must be read differently than the previous ones I posted. While the earlier graphs were singular looks at each channel, the graph below is a look at a single channel at various volume settings. I wanted to start with the system volume level maxed, but anything over 50 introduced hiss, so a setting of 50 will be the maximum limit for me. I took a reading at 10 click intervals (50, 40, 30, 20, 10) and did not see any wide variance in system response. The relative differences between the peaks and valleys remains the same across the volume range.
This is great! I'll have to take the same sets of measurements for the other channels as well, but I'm happy with the front door speaker at least
Front left door output of a 2016 IS 350 (non Levinson stereo) taken at 10 "click" intervals between volume settings of 10-50.
Now that I've measured all the channels' frequency response at a baseline volume, I wanted to make sure that the frequency response did not change with volume settings in the car. Many manufacturers will roll off bass/highs as the volume **** is cranked in order to not sound like crap.
There really isn't a way to combat a system that has volume dependent EQ'ing. You basically either have to live with the constantly varying frequency response, or set the head unit volume at a specific # and leave it there forever and use an outboard volume **** (and lose steering wheel volume control in the process).
I'm glad to say that thus far, I haven't found any heavy indication of volume dependent EQ'ing.
In the graph below, it must be read differently than the previous ones I posted. While the earlier graphs were singular looks at each channel, the graph below is a look at a single channel at various volume settings. I wanted to start with the system volume level maxed, but anything over 50 introduced hiss, so a setting of 50 will be the maximum limit for me. I took a reading at 10 click intervals (50, 40, 30, 20, 10) and did not see any wide variance in system response. The relative differences between the peaks and valleys remains the same across the volume range.
This is great! I'll have to take the same sets of measurements for the other channels as well, but I'm happy with the front door speaker at least
Front left door output of a 2016 IS 350 (non Levinson stereo) taken at 10 "click" intervals between volume settings of 10-50.
Wow nice job and thank you for sharing!!! Was wondering if maybe the Subwoofer had higher Roll off then the other channels?
Derek (or anyone else that would like to comment) - I have been searching all over the internet to get some information about the base stereo system in my 2014 IS350. I want to upgrade the sound, but I don't know how long I will keep the car. I don't want to spend thousands on a system and then sell the car in a couple years.
Derek, based on your analysis, would replacing only the existing OEM speakers provide a significant improvement in the sound quality? I am thinking of spending $600 to $800.
Or do I need to go the route of a JL Audio Fix 86, JL XD700 AMP and C2-650 speakers? This will cost me about $2,000, which is a lot of money if I sell the car within the next couple years.
03-15-16, 08:43 PM
Base Stereo - RTA Analysis
