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Upgrading standard sound on Model S and using Chromecast

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I took delivery of my Model S 70 last September and got it with the standard sound system with the idea of upgrading it later. This is going to be long post (and my first post too). My hope is someone trying to do something similar may benefit from my post.

I have a signal processing background in audio and quite familiar with measuring and tuning audio systems, but this was the first time trying to to tune an audio system in a car.

After contemplating multiple options (Reus, Lightharmonic, NVX sub), I decided on doing a custom installation. There were multiple reasons I went this route:
  1. I needed to be able to bypass any factory tuning/EQ: If I just replaced the factory speakers, it likely will not sound quite right as the speakers are already fed signals with factory tuning designed for the standard sound system and to my knowledge there was no way to bypass and get line-level/pre-amp signal output from Tesla's DAC/processor.
  2. I needed to be able to provide a digital signal input for the best possible audio quality.
  3. I wanted to be able to tweak the tuning to my liking.
  4. I wanted the best possible imaging for the driver and also be able to switch it to get a decent imaging for both driver and passenger (i.e. be able to have at least two presets) so that my spouse does not say I get all the good sound!
  5. I wanted to use Tidal, but not through Bluetooth. Chromecast Audio works better (yes there is an audible difference even at highway speeds) and yes it is possible to use Chromecast in your car despit what Google tells you. Skip to Digital input 2 if you want to see the details
Components selected
All this pointed to needing a DSP/sound-processor and this is what I choose to install:
  • Helix Pro DSP
  • JL-Audio HD900 5ch Amp
  • Focal ES165 KX2 Component Speakers: These are two way speakers that replaced the front door speakers and the tweeters.
  • Focal 165AC Coaxial Speakers: These replaced the rear door speakers
  • NVX Subwoofer and Enclosure (without the amplifier)
  • A 120w pure-sine wave inverter (I will come to this later on why I needed this)
I am sure there are infinite choices on choosing speakers amps DSPs. I wanted to get good performance without breaking the bank. Cars being inherently noisy environment, I did not want to go overboard.

Installer and Cost
I used Custom Car Stereo in Houston and Jonathan helped me choose the various components (due to my limited experience with car stereo). Both the Focal speakers and Helix DSP were on sale at that time (on Crutchfield) and Custom car stereo matched the price, so it made my choice on the components a little easier. It cost me a little over $5000, and out of which about $2000 was the installation cost.

Note: Most of what comes below is with respect to DSP Helix Pro, but I think a lot of this may be equally applicable to other processors.

Signal path
Helix DSP Pro supports 8ch Line-level (RCA) analog input, and 8ch Highlevel (speaker) inputs and a digital optical (up to 96kHz) and one digital coaxial (up to 192kHz). Helix DSP pro comes with a software you could use to tune and configure through a PC USB input and the software has vast number of options to get things setup just the way I wanted it.

Analog Input
The standard audio has 5 channels Front Right (to door speaker and tweeter), Front Left (to door speaker and tweeter), Center, Rear right and Rear left. All the five channels were connected to the Highlevel input of DSP Helix. when I

Digital Input 1 (coaxial)
I requested that a digital coax cable be pulled all the way to space under the touch screen. My intention was to mostly use this for tuning/Eq for digital input and doing measurements

Digital input 2 (optical)
This is my primary listening setup. Helix DSP allows the use of coax or optical input (through a hardware switch) but not both . I have a Chromecast Audio connected optical out -> ifi spdif ipurifier -> optical input of DSP helix. iFi spdif purifier is not required, but I had one I was not using and heard an audible difference in parked car or at low speeds. Chromcast Audio's spdif output quality is not that great by itself.

Setting up Chromecast Audio for car is easy but needs a little creativity. This assumes you have a phone that is capable of teathering that you intend to use in your car (I use android so I cannot comment on iOs devices) and second android device (just for the setup).
  1. Install Google Home on both Android devices.
  2. Enable hotspot on the phone you intend to use in the car. Let us assume the hotspot is named 'EV-Audio'
  3. Connect the second Android device to the hotspot and also use Google home app to configure your Chromecast Audio device and point it to 'Ev-audio'
Now when in your car, you can enable hotspot and stream to Chromecast Audio using Tidal App or you can stream local files on your phone using apps such as BubbleUPnP. One cool feature of BubbleUPnP is that even if you had DSD files, it will resample it to 96kHz, which is the max rate supported by Chromecast Audio and which is also the internal sampling rate of Helix DSP Pro. I use AuI ConverteR and store all mymusic as 96kHz flac in my phone and also as 192kHz flac in the USB drive. I try to avoid resampling by processing limited hardware and instead do offline resampling on my PC (if you are OCD on such things).

If you are worried of data usage charges, you can use Tidal offline and simply turn off data (but still keep tethering on). i do not switch off data and I have not exceeded my data limit.

Both Chromecast and ifi spdif ipurifier needed power (very little though), you could power them off of a 12v lighter and USB cigarette lighter adapter, but I choose to install a inverter for flexibility.

I used 6 channels (Front right and left component speakers, rear left and right coaxial speakers and two for Sub) output from DSP Helix, going into the 6 channels of the JLA amp. Then output from the amp went to the four speakers and a single NVX sub (two channels going into single sub).

A knob was installed under the touchscren to control the gain on the Sub, I also added a remote for DSP Helix as I figured this was the only way to control digital volume.

I am not going to go in to detail of how I tuned each speaker or how the crossover was setup, instead I will provide dropbox link here preset 1 best for driver and preset 2 best for driver and passenger to my configuration files. You can easily download the DSP PC-Tools software and look at them (choose DSP Helix Pro and not Mk2). If you choose to install a system with the same setup, then it is very likely that you may be able to directly use these and may be tweak them a little.

I setup crossovers within the helix DSP. A good thing was Tesla's processor was putting out full range signals on all channels except center (I disconnected the center speaker and do not use it), so crossover was a little easy for the analog input. I used 80Hz as the corner frequency for both Sub and the other four channels, Linkwitz with 24dB/octave roll-off.

Factory default tuning/EQ
See below (or this link in case I do not have permissions to post images) for the the default Tesla factory tuning for the center, front and rear channels. Measurement was done using REW by playing pink noise from USB and measuring it directly from the output of HelixDSP and HelixDSP was set to pass through the signals from speaker level input. It also throws some light on hove the standard sound system is tuned (boosted base and upper treble) to compensate for the performance of the factory speakers.

DSP Helix has a auto-tuning function that either you can do if you have compatible mic or the installer can do. I was not happy with the auto tuning that the installer did (not their fault, just a matter of personal taste) and did the tuning myself using REW and UMIK-1 (there are numerous Youtube videos if you want to do it yourself).

There are two options:
  1. You can tune separately for the digital input and for the analog input (from Tesla's processor/head-unit) and have them as two presets. I felt this would be a pain to keep switching presets. Also if you wanted two setups for best imaging (one for driver and one when the passenger is present), then you will need four presets.
  2. Helix DSP has the ability to automatically switch to digital input when a high enough signal is applied to the digital input. Also it has a feature where you can apply a separate EQ to compensate for any factory tuning when a analog input is applied.
I choose option 2. I first measured by playing pink noise through digital input and averaging measurements from each speaker (measured at ear height from driver's seat). REW can be used to do a EQ if you provide a target curve ( I used a slightly base boosted 3dB below 150Hz target and then gently sloping starting from 1kHz, loosing 6dB at 20kHz). REW will spit out parameteric EQ values that I simply plugged into the channel EQ of DSP helix then tuned it by ear a bit.

Once I was happy with the digital input EQ (this is the true EQ for the speakers that were installed), I had the EQ on and then played pink noise through analog input (pink noise file from USB stick). I then used REW to compute parametric EQ values. this is the additional 'correction' that needs to be done to compensate for factory tuning when using analog input.

Setting up the right delays is very important for imaging. Sitting at the drivers position I measured the distance from each speaker and plugged them in to the timing information of DSP Helix software. Then I adjusted it using tracks that were predominantly vocal so that the image was a little to my right but not directly in front (the reasoning is a little complex than I wish to elaborate here). II saved this as the first preset

I then sat in the passenger seat and and adjusted the delays (from the previous setup) such that the vocals appear to be coming from directly in front of me. I verified that the driver will also hear something similar with imaging directly in front but would be a bit compressed on the left (which is a compromise). I saved it as a second preset.

Other considerations
After setting up everything I realized that when playing music through digital input, since I gave digital input priority, I will get no sound for anything routed through the head-unit (turn signals, warning chimes, navigation etc). Also I found that Android was a bit unpredictable in turning off music on incoming calls when streaming to Chromecast Audio. This meant, I had to give analog input priority. Having analog input at a higher priority meant that the music gets interrupted at every turn or anytime there is a chime (like exceeding speed limit by 1 mile) which was a major annoyance.

Fortunately, within each preset DSP Helix allows two signal paths. One that is purely digital and another that can either be purely analog or you can mix both digital and analog. So I setup a pure digital path and one with digital and analog input signals mixed with digital singal at a reduce volume. This turned out to be a good compromise so the music will not be interupted instead will be reduced in volume.

Feedback on the installer I used
I am in no way affiliated with Custom Car Stereo of Houston, I was looking for a installer who has worked on Tesla's in the Houston area and I found them through this forum as they had previously done NVX installations. I was a bit nervous as i think this was the first full fledged custom installation they did non a Tesla. They were very professional and completed the installation on time (3 days). Installation was clean and I had not have any issues after installation. All components were stealth (i.e., you will not notice any change in the factory looks in the interior). I would give 9/10 on the quality of work (if you are OCD you may notice a few minor things if you scan the interior inch-by-inch).

I hope you find this helpful and I will try to answer questions as my time permits.
Impressive system! The info on the outputs available from the head unit is very useful for me.

I'm just about to take delivery of my second S - this time with the standard system. I'm expecting to want to upgrade it but I think our options over here in the UK are somewhat limited.

Anyone here from the UK done an upgrade of the standard system?
Thanks @BanburyRick. I would think Helix DSP pro and Focal both being European manufacturers, you should be able to get them, you could substitute the JL Amp for a Masconi or similar, but make sure they are not power hungry. I have no idea about cost involved for installation in the UK.
Focal are great speakers. I worked at Tweeter (defunct A/V chain) in college and I really liked reading your post and your thought process about why you chose components. I don't have the stomach for something like this but my daughter really loves high end audio and so I am thinking of how to improve the audio quality in my new Tesla. Honestly the standard sound is such an improvement over my Leaf that my daughter and I are reasonably placated by it until we get home and can really jam out. My wife, after I convinced her to splurge on a great system for our then apartment, has also warmed up to high quality sound systems but isn't an audiophile (yet).

Your choice of DSP is especially interesting to me as pre-processing the sound and then using chromecast isn't something I could've envisioned. Thanks for posting this!
Your choice of DSP is especially interesting to me as pre-processing the sound and then using chromecast isn't something I could've envisioned. Thanks for posting this!
With Chromecast you can either stream Tidal (or any other music streaming that supports Chromecast) directly or you can use BubbleUPnP to cast from Tidal , Qbuz, google music and some cloud services or local files. BubbleUPnP will transcode to 96khz if needed.

There are other options too for streaming in the car like Auralic Aires mini or Sonos (and now Poly from Chord) that are more feature rich. But nothing can beat the price of Chromecast, its tiny footprint and close to negligible power requirements.
Photos of this setup?

Here you go.
I have not included the pictures of the front and rear speakers because from the outside they just look like the factory installations and no modification was necessary to the doors or pillars. I do not have pictures during the installation process (I can ask the installer if they took some)

Amp, processor, chromecast, inverter installed in the foot-well

Everything hidden with a simple carpeted board with space to spare!

NVX sub

Bass control knob Just under the touch screen to control the sub gain.
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After several months of living with this setup I have some updates:
  • Yes it still sounds as good and may be a bit better even with the speakers having had time to break-in.
  • But my honeymoon with Chromecast Audio has ended. While chromecast does seem to stream locally and use tidal offline, it still needs a proper internet connection when it starts up and sometimes when switching tracks. This means on longer drives out of city where there is no cellular 3G/2G/LTE, chromecast audio does not work!
So I went searching for alternatives and found a few. But if you want to do Tidal offline, I found out the painless way is iDevice and airplay or a rooted android phone so you can audio cast.
  • Apple airport express is a good option for $100 if you are happy with streaming only 44.1kHz audio and tidal
  • I found another cheap nifty little device for $30 (EZCAST M7 WiFi Audio Streamer), there are many similar devices, rebranded from China. It can be powered from USB, supports DLNA and Airplay!, but wifi streaming is spotty for anything more than 48kHz. A no go for me but may work for you.
  • Finally, I settled on Auralic Aries Mini. Yes it is more expensive, but what a difference it makes! Streaming is stable, optical output is very clean and is immediately evident. It supports any format you throw at it. Also supports Upnp/DLNA/Airplay and streams wireless or bluetooth.
Finally, I also had a chance to spend a few days with a P85 loaner that had the Ultra High Fidelity Sound (UHFS) audio upgrade. I had my 70S for service as it reported 'reduced power' due to a kink in the coolant system. I loved that the P85 for being quick but UHFS was such a big downgrade from the custom sound system I had, I derived some guilty pleasure from going the custom route :p. In Spite of having only the tweeter elements on the pillar and the two front door speakers for staging, the imaging on my setup had greater width, depth and height, better clarity and stereo separation. In comparison, UHFS sounded so compressed and mushed to a couple of feet wide directly in front of me.
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I loved that the P85 for being quick but UHFS was such a big downgrade from the custom sound system I had,
I also have a P85 loaner right now and the UHFS sounds awful!! No matter how much I tweak the settings, I still can't get it to sound as good as the stock speakers in my 60. I feel like I am listening to music in a tin can. I would have been very disappointed if I had paid for that "upgrade".
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I also have a P85 loaner right now and the UHFS sounds awful!! No matter how much I tweak the settings, I still can't get it to sound as good as the stock speakers in my 60. I feel like I am listening to music in a tin can. I would have been very disappointed if I had paid for that "upgrade".
It's probably just the non audiophiles plebs like me and you who think this. My mum has a Merc E class with a Harmon Kardon stereo which is worth an extortionate amount of money, and to me it sounds tiny too. Maybe that's what the audiophiles want?
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As an experiment to see if I could do the install myself, I started with replacing the factory rear speakers. As shown in your trace, the rear speakers have much of the LF pre-EQed out. I don't feel like this was much of a help, except maybe making the HF a little smoother from the rear. I really need a processor in order to flatten the signal to get any meaningful improvement.