"PURE" Digital Factory Infotainment Integration Honda Civic Bose / Acura Integra ELS

[Ash @ S2i Audio]

Sorry a couple more.

Do all car alert sounds, voice nav, and phone call audio also run through that same digital audio output? Does your fake engine sounds also run through it?

No worries at all. The answer to this in the above post.

Have you tested phone calls without the ANC hooked up? Do you know what the call quality is like on the other end?

I have tested phone calls and they work. ANC doesn't change how you sound to others over the phone, it's for engine sounds and noise cancellation within the car for your (dis)pleasure.

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[Ash @ S2i Audio]

LOL I am dumb. Please take a picture if you can. If not no worries, hopefully my installer will understand this. I will stop bothering you now.

Thank you again for all your help. I think I fully understand the full scope of it all. You have been such an immense help in figuring out how to add an aftermarket system and to get the best sound quality. I am truly grateful that you also have a desire for a great sounding system, and are much smarter than I am. THANK YOU GOOD SIR!

Unfortunately I never took that photo before I Tesa-taped the CE2 to RCA terminal conversion (in my case CE2 to RJ45 as that's what my amp uses for SPDIF input).

That said, you may not need the 75 ohm parallel resistor if your amp has the proper impedance termination inside it (chances are it does). Try it out without the resistor first and if the head unit doesn't seem to latch on to the DSP, or you experience sporadic digital dropouts, then add in the resistor. One end of the resistor goes to the outer terminal of the RCA and the other end goes to the inner terminal. It's like a short circuit, but with a resistor instead.

 

[Ash @ S2i Audio]

The "easy" way that has always been available to us is to connect the speaker level outputs from the factory amp into your DSP, and then you don't have to worry about any of this complex stuff. It's a perfectly valid approach. The reason you may not want to do it (and why I don't want to) is because you are then at the mercy of the quality of the factory D/A converter, amplifier, and fixed DSP that you need to undo in order to get a halfway decent starting point. All of these actions introduce distortion and other issues. But again, all doable.

If you want the highest possible fidelity and have already spent a lot on high end speakers and amplification, the way to take the most advantage of those parts is to intercept the digital signal going into the factory amp and bypass all the factory D/A and DSP.

As for chimes etc, they are all on the B4/B5 pairs and I think there's one more called MIX as well (at least there is on my Integra ELS amplifier). As far as I have tested, they are all analog low-level signals so you just feed them into your DSP alongside the SPDIF source and you tell the DSP to mix these signals in, and duck the SPDIF when any of the analog signals are transmitting.

 

[Ash @ S2i Audio]

Also, I spent months figuring out what connectors types are for the amp I/O. From the image of the Bose Civic amp, it looks like they are the exact same connectors as the Integra's ELS amp.

The larger plug that carries the speaker signals was the really difficult one to identify, but I did (no one else has figured it out yet). The problem is that there is only a board-mount flavor available for the male side, so you have to hack the connector together with mean soldering skillz. The connector part is this. Here's the female side if you're building a T-harness for the high-level input to DSP approach. If you're going pure digital input you only need the male side alone.

The smaller connector that houses the RS485 and analog inputs is this. Thankfully, it does have a cable-type male connector available if you need to plug back into the amp (again, if doing the analog solution... not needed for pure digital).

 

[matttheazn]

Your factory HU was happy to run as long as the SPDIF connection was made to anything? It did not matter if the RS485 connection to the amp was made or not?

I think I will tap before the Bose amp. AA should be controlling the Navigation volume digitally before going. Looks like I just need to tap B4, B5, B12 and B14 for remote.

so you have to hack the connector together with mean soldering skillz.

Did you need to get to the back of the HU at any point? Or did you do everything at the amp connection area, which I assume was in the passenger kick area?

The smaller connector that houses the RS485 and analog inputs is this. Thankfully, it does have a cable-type male connector available.

Do you have spare connectors I can get from you premade? Both the RS485 female end to send out to the and a SPDIF to coax end? I can pay you whatever.

 

[Ash @ S2i Audio]

The head unit will continue to operate without any connectors plugged into the amp. It's a pretty dumb HU, thankfully. AA doesn't do any volume control; the head unit makes those decisions regardless of the source selected. This applies to AA navi sounds too.

Yeah I can make connectors for you. DM me so we can talk through the specifics of how you want to hook everything up because there are some choices to make. Do bear in mind it will take me some time to get to it because I have a day job, but I'm happy to weekend warrior some stuff for you.

You don't need to touch the head unit thankfully. And the factory amp connectors are REALLY easy to get to. Literally don't even need to unscrew anything to get to them - just pop off a few panels in the passenger footwell.

 

[Ash @ S2i Audio]

Would you want to use the factory volume control, or are you going to control the volume through your DSP remote knob?

 

[matttheazn]

Would you want to use the factory volume control, or are you going to control the volume through your DSP remote knob?

DM sent

 

[Ash @ S2i Audio]

Would anyone here be willing to help me test and confirm the actual encoding of the volume signal on the Civic is the same as the Integra? It would allow me to definitively confirm or adjust my encoding for the Civic, so that the volume control device can definitively work for it.

It would require purchasing one inexpensive piece of equipment, and of course requires a windows laptop.

It would be great if I got two volunteers - one with Bose and one without.

 

[Ash @ S2i Audio]

I've been quiet for a few days because I ran into a problem with the volume control device that required a redesign. TL;DR, All is well now.

The longer story: the strategy of replicating a manual volume knob aka potentiometer with a digital potentiometer was not the right strategy, at least not for my DSP. The Arc Audio ecosystem uses relatively low impedance volume controls (500 ohms in this case) which is an intentional design choice for reasons I won't get into here, suffice it to say they know what they are doing. The problem arises from the fact that there are no 500 ohm digipots (the closest is 1 kohm) because they will be susceptible to ripple and noise.

I was mistakenly under the impression that the ratio of the impedances would suffice, but electrically the power input for the digipot from the DSP just can't overcome the much higher impedance.

So, back to the drawing board. I ended up switching the strategy completely from applying a resistive load to the static voltage supplied by the DSP, to simply using a DAC as an analog variable voltage source, bypassing the DSP's potentiometer power source completely. This is a much better design and will be compatible with more aftermarket DSPs (so long as they use analog voltage as the remote control strategy). The only thing that would need to be figured out for each DSP is whether the amp is sending 5V or 3.3V into the remote control as the VCC power source (the two industry standards). I could feasibly make this a product with two models - one for 3.3V amp remotes and the other for 5V remotes.

The new device is the little red PCB on the lower right corner. I'm also planning to design a PCB to micro-size this whole device, and I found a board-mount isolated power supply that I can use for even further shrinkage.

 

[matttheazn]

Please keep sending updates . I will be waiting to see what you come up with. I have that DSD board in my cart.

 

[Ash @ S2i Audio]

I will!

Which DSD board? Sorry if I'm being forgetful...

 

[matttheazn]

It would require purchasing one inexpensive piece of equipment, and of course requires a windows laptop.

 

[Ash @ S2i Audio]

Oh, duh. I forgot that was the brand name of the sniffing device and was thinking "Direct Stream Digital board?" lol.

I can build you a connector harness to plug one of the harnesses that goes into the factory amp temporarily to take the measurement with the RS485 sniffer (the device above). And that connector would be one of the pieces you'll need for factory integration anyway, so it wouldn't be wasted $$.

Ping me if you want to move forward with helping me with this testing!

 

[Ash @ S2i Audio]

Was quite busy this weekend:

Automotive-grade connector (the same brand Honda uses):