2020 Si Full Audio Rework

[jimmyreal]

...the built in DSP makes upgrading just the speakers kind of pointless.

This is my hang up. It’s pointless to drop $2-3k on power + speakers, then send them a signal that’s all jacked up.

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[himynameisaaron]

This is my hang up. It’s pointless to drop $2-3k on power + speakers, then send them a signal that’s all jacked up.

I mean, I guess I should clarify. If you do just speakers, most notably the woofers in the front and use a 3rd party EQ (whether viper or on your smartphone) you can clean up the muddy bass and dial it in a little better. I'm not gonna say it was an absolute waste of time but without upgrading the amp (which I'm gonna do soon) and/or add a DSP you won't notice a big difference. If you have the money/time/know how and wanna do it I'd say go for it but don't expect miracles.

 

[bikejog]

I mean, I guess I should clarify. If you do just speakers, most notably the woofers in the front and use a 3rd party EQ (whether viper or on your smartphone) you can clean up the muddy bass and dial it in a little better.

Not just the bass, the stock mids and highs are trash too. Vocals sound like I had wax in my ear and the only way I can tolerate the highs at high volume was with the windows down. Replacing the fronts make all three better, however, as you and I have found out, the volume level won't increase much and you'll be left wanting more.

 

[JT Si]

There are plenty of resources to find on this forum and other places, but I will sum it up for you here:

The head unit sends a digital optical signal (plus aux signals for things like chime sounds) to an AMP/DSP unit. The unit decodes the signal, mixes in the aux signals, and send all 10 channels through a DSP that performs crossover and mixing.

The signals are then amplified and sent to the speakers.

No matter what you do, if you do not remove the AMP/DAC you are using DSP altered and crossed over signals. You can try to use signal restoration devices and see good results, but you're really just compounding by continuing to alter a bad signal.

There is a box by Axxess (https://axxessinterfaces.com/product/AXDSPX-HN3) that replaces the OEM AMP/DSP box, accepting the optical and aux signals and allowing you to allocate channels as you want, cross them over (or not), and removes the signal altering DSP entirely.

It will require you amplify every channel you want to use. If you want to use component sets for front/rear woofer/tweeter you can get away with only amplifying 6 channels (FR/FL/RR/RL/C/Sub).

===========================

I replaced all the OEM speakers, including the subwoofer, utilizing the OEM AMP/DSP setup. It's not the best sounding system I've had, but it still improved the sound enough I am satisfied to not mess around with getting the Axxess interface, buying amps for the channels, and all that jazz.

 

[Snmtazz70]

Done alot of audio and mine sounds damn good considering not a crazy sub box because of weight.

 

[jimmyreal]

There is a box by Axxess (https://axxessinterfaces.com/product/AXDSPX-HN3) that replaces the OEM AMP/DSP box, accepting the optical and aux signals and allowing you to allocate channels as you want, cross them over (or not), and removes the signal altering DSP entirely.

I’ve been missing this, because it’s exactly what I’d want to start a build with, if I end up building.

If building a SQ system, I’m going to amp all the channels I use anyways, probably a 6 channel powering front tweeter/mids via passive crossover, rear mids, and a bridged sub.

 

[ewplayer3]

There are plenty of resources to find on this forum and other places, but I will sum it up for you here:

The head unit sends a digital optical signal (plus aux signals for things like chime sounds) to an AMP/DSP unit. The unit decodes the signal, mixes in the aux signals, and send all 10 channels through a DSP that performs crossover and mixing.

The signals are then amplified and sent to the speakers.

No matter what you do, if you do not remove the AMP/DAC you are using DSP altered and crossed over signals. You can try to use signal restoration devices and see good results, but you're really just compounding by continuing to alter a bad signal.

There is a box by Axxess (https://axxessinterfaces.com/product/AXDSPX-HN3) that replaces the OEM AMP/DSP box, accepting the optical and aux signals and allowing you to allocate channels as you want, cross them over (or not), and removes the signal altering DSP entirely.

It will require you amplify every channel you want to use. If you want to use component sets for front/rear woofer/tweeter you can get away with only amplifying 6 channels (FR/FL/RR/RL/C/Sub).

===========================

I replaced all the OEM speakers, including the subwoofer, utilizing the OEM AMP/DSP setup. It's not the best sounding system I've had, but it still improved the sound enough I am satisfied to not mess around with getting the Axxess interface, buying amps for the channels, and all that jazz.

That’s exactly what I want. It’s going to add a chunk of change to the project, but that will give me the best chance to install a nice audio system with the least amount of factory wiring modification and splicing.

 

[PandaXpress]

If you are going to put alot of money in the sound system you should get a way better DSP
At lease a AudioControl DM810 quality DSP or higher
https://www.audiocontrol.com/car-audio/digital-signal-processors/dm-810/
Because not all DSPs sounds the same
does the AXDSPX-HN3 actually does summing of the channels?

That’s exactly what I want. It’s going to add a chunk of change to the project, but that will give me the best chance to install a nice audio system with the least amount of factory wiring modification and splicing.

 

[kostas]

The OP of the thread I linked to tested the SPIDF signal with a cheap decoder and said it didn't work. But then there was one member here whom wrote gibberish about it being standard SPDIF and as best I can understand from his post, he said the AMP can take a standard SPDIF signal, but nothing about if the SPIDF output from the HU was standard or not, but he could also be saying the HU SPDIF output is standard.

The only success with completely bypass the stock amp is this https://www.civicx.com/forum/thread...-speaker-audio-of-sport-touring-type-r.52248/. But only one guy did a review of it and found the Bluetooth Hands Free link had really bad echoing problem.

And there's a guy in this thread https://www.civicx.com/forum/threads/premium-amplifier-out-wiring-harness.43631/ that will mod (destroy??? lol..) your amp for $260 plus shipping. Not sure if I get what he's trying to do. The way I read his post is he's bringing out the low level from the preamp, but isn't the preamp after the DSP? So that's useless no? I'm not sure.

But if you want to TOFTT and try to see if you can decode the SPDIF, you can buy one of these Antenna Adapter and remove the square plastic housing and you'll get the round connector and wiring that will mate with the stock SPDIF connector to the amp.

I tested the digital audio from HU to the AMP yesterday.
It IS a standard SPDIF. I could listen the HU to my laptop!!
And this opens a whole new approach for fully digital sound with aftermarket DSP & AMP...!

 

[bikejog]

I tested the digital audio from HU to the AMP yesterday.
It IS a standard SPDIF. I could listen the HU to my laptop!!
And this opens a whole new approach for fully digital sound with aftermarket DSP & AMP...!

That's good news dude. This indeed opens up to another approach, however there's still a small hurdle you must overcome to mix in the analog audio with the digital. The way I think the amp logic works is this

• All analog sounds (nav, some system beeps, '20 Si engine sounds) are mixed in unchanged with the SPDIF
• When nav voices sound, amp will lower the digital sound volume. Or the HU will lower the SPDIF signal and in that case, it's even easier.
• There's a RS485 message opcode that tells the AMP when Hands-Free is active and in that case, the amp will mute the digital sound and mute all speakers except the front door speakers.. Or the HU will mute the SPDIF signal and in that case, it's even easier.

These can be done with an Arduino as follows. The hard part might be to find a DSP that provides an open external control interface (UART, SPI, I2C, Ethernet, etc) that the Arduino can handle. I have already decoded the Honda RS485 signal enough to provide all the volume, tone controls, fader, DTS on/off, and SVC (speed volume compensation Off/low/mid/high settings).

 

[kostas]

I have already decoded the Honda RS485 signal enough to provide all the volume, tone controls, fader, DTS on/off, and SVC (speed volume compensation Off/low/mid/high settings).

Really? That's great!! I would be very appreciated if you would share it...

Now, about the schematic. I have the same in my mind except the Arduino part plus I'm going to convert the coaxial to optical inside the HU .
The DTS and SVC are not important to me.
As for volume, tone, balance and fader, those can be controlled by the remote control that some DSPs have (e.g Audison, Helix). Some provide only volume (e.g Eton) and the rest (rarely used) through a phone app.

FYI while recording with the laptop I had a call. The phone was BT connected to the HU. The ringtone was recorded as well, in other words, the ringtone goes through SPDIF to the AMP.

 

[bikejog]

Really? That's great!! I would be very appreciated if you would share it...

Now, about the schematic. I have the same in my mind except the Arduino part plus I'm going to convert the coaxial to optical inside the HU .
The DTS and SVC are not important to me.
As for volume, tone, balance and fader, those can be controlled by the remote control that some DSPs have (e.g Audison, Helix). Some provide only volume (e.g Eton) and the rest (rarely used) through a phone app.

FYI while recording with the laptop I had a call. The phone was BT connected to the HU. The ringtone was recorded as well, in other words, the ringtone goes through SPDIF to the AMP.

My memory for the Hands-Free was incorrect and you're correct that it's carried via SPDIF.

You have another SBC in mind besides the Arduino? I pick the Arduino because of its low power consumption

On the remote controls. I haven't really spend time looking thru what're available yet. The only remote controls I'm seeing out there are via analog pots. If that's the case, are you thinking of interface with the pots using DACs and perhaps driving some custom hardware? Would be nice if there's a DSP that allows open digital control protocols.

The DTS and SVC might be used to switch between Equalizer Profiles, etc. Generically, could be used to pick options.

I don't feel like just sharing the protocol. If you have a detail requirement of what you want to accomplish, then I might be willing to help you. I'll see if I can (no promises) take a video showing I have decoded the RS485 signal later on today.

 

[kostas]

You have another SBC in mind besides the Arduino? I pick the Arduino because of its low power consumption

Nope... I intentionally avoided this part cause i know it's quite hard, basically the most difficult of all.

The remote controls must be digital. My guess.. After all, it's easier also for the designer.
But why to mess with the remote control's port?? I think I lost you here...
Take a look at this solution as a candidate I'm thinking of
AMP w/DSP: https://www.audison.eu/products/ap8-9-bit/
Remote control: https://www.audison.eu/products/drc-mp/

The DTS and SVC might be used to switch between Equalizer Profiles, etc. Generically, could be used to pick options.

That's a good thought!

I don't feel like just sharing the protocol.

It's totally understood!
I haven't something in mind. I just started yesterday after I tested the SPDIF and saw that there is something promising here (only digital flat signal!!)

 

[Misa33]

Does RS485 carries some audio payload (eg Navigation sounds, system beeps etc)?

If that is the case, then we need some kind of signal processing and mixing. For most people is not acceptable to discard all the audio payload that is coming from RS485. The audison remote control cannot help unless we decide to keep the OEM Amp to handle the center speaker.

Arduino (or any other SBC) idea, is promising. The difficult part will be to mix the 2 audio payloads by programming the computer. Maybe I can give it a try…

We know for sure that Axxess AXDSPX-HN3 has already managed to implement your idea.

 

[bikejog]

Nope... I intentionally avoided this part cause i know it's quite hard, basically the most difficult of all.

The remote controls must be digital. My guess.. After all, it's easier also for the designer.
But why to mess with the remote control's port?? I think I lost you here...
Take a look at this solution as a candidate I'm thinking of
AMP w/DSP: https://www.audison.eu/products/ap8-9-bit/
Remote control: https://www.audison.eu/products/drc-mp/

Below is a video showing just the volume and bass. Arduino is easy. The hard part is finding out the DSP control protocols. I could reverse engineer the protocol like I have done for the Honda RS485, but my motivation is extremely low right now since my current setup is already sounding very good and I'm super happy with it. It doesn't need anything else really, but I might just add a sub just for the hack of it, but the bass is pretty slamming (can shake side and rearview mirrors) as is.

I didn't meant to mess with the remote control. I meant to have the Arduino replace the Remote Control. That's the ultimate goal isn't it? If your goal is to keep the DSP remote control in the car, then all you have to do is to remove the Arduino block in my block diagram and you a complete working system. But make sure you test Hands Free call to make sure there's no echo problem as one guy found with the Axxess AXDSPX-HN3.