Car Navigation w/ Buffalo III DACS project

[kotani]

Hello everyone. I posted this in DIYMA forum, but I didn't have many people's interest, so I figured I would post here as well. Please let me know what you think about this install...

The point of this project is to have a aesthetically simple install in a e39 BMW, with excellent SQ from a navigation head unit.

First, the Navigation unit is a Panasonic CN-HX3000D (I live in Japan). It features a flipout 720p screen, with an HDMI input (w/HDMI audio btw).

The problem is that the unit does not feature RCA outputs, so I am stuck with the 50w x 4 max output from the head unit amp. I didn't want to install a second SQ oriented head unit, and def. wanted the navigation and the 720p display.

So this here is the idea for the project. Take apart the navigation unit, find the final dac section, tap the digital audio I2S lines, feed the lines to a external dac, and then to external amps. It seemed difficult at first, but this is what I have so far.

Head unit (Panasonic CN-HX3000D):


DAC located inside navigation unit, and I2S(BCK, LRCK, D-IN1(Front R+L) D-IN2(Rear R+L)) lines tapped and fed outside the unit to a Ethernet cable recepticle


Now that I got the raw digital lines outside the unit, it was time to figure out which dac to use. I ended up using a pair of Twisted Pear's Buffalo III's(Perhaps worlds first?).

Also, I used the Twisted Pear IVYIII's for the output stage.

The problem of course was powering the units. The Buffalo III's include 3 on-board trident shunt regulators, so I decided to power the units using a adjustable DC-DC converter set for 5.25 volts directly. I'm hoping the shunt units will help eliminate the DC-DC's noise.

The IVYIII output stage requires +/- 15 volts to operate, and need good clean power. I used a adjustable DC-DC converter set for +/-16.8 volts and fed it to a modified twisted pear Placid BP HD with the bridge rectifier circuit removed, so it could work with the DC +/-16.8 volts instead of AC that would usually be fed from transformers.

Power supply board w/ the two DC-DC Converters.


Placid BP HD, and the two Buffalo DAC and IVYIII's powered successfully off of a 12v DC source.


Here is the I2S line coming from a STP Ethernet cable from the head-unit going into the Buffalo DAC's


I am able to get 4 balanced outputs from the two IVYIII units.


Where to connect the balanced outputs? The Mcintosh MC430 of course!



I will have the MC430 feeding the front (HAT Clarus C61-2 and rear fill speakers (HAT Imagine I51-2).

The IVYIII also features single ended outputs that can be used at the same time. I have pulled the L+R pair from the Front DAC to a MCC402 that will be powering a pair of Legatia L8V2's (crossed as subwoofers) on the rear deck as IB.


As for now, the system sounds great. Because the DSP, the Dolby Digital Processor, the ADC, and the Volume control happens before the DAC in the navigation unit, I am able to retain all of the functions on the Navigation, although I am worried about the internal bit rate of the volume control and the DSP system. I have been unsuccessful in finding a data sheet for the TI DSP that is in the head unit.

My next step is to fit the external DAC into a case, and then I should have the unit ready to be installed into the car. I have the L8V2's on the way, and I'm currently negotiating L1 Pro R2's to replace the stock Clarus tweeters.

I also have 2 pairs of balanced cables, and a pair of RCA's coming from Blue Jeans Cable.

Please let me know if you anyone has any input on the project. I apologize for the messy layout of wires. It's just a prototype.

Anyways, I will keep everyone updated in the future.


One thing I would like to ask. I would like to be able to extend the I2S signals to the trunk of the car, but even with STP Cat5e cables, 3 meters seems to be the limit before I get lock issues.

Can someone help me make a I2S extender? I seem to be stumped here. Thank you in advance!

[Bertje]

Very nice project (or proto..) As far as I know I2S should be connected with very short wires. If you really have to go a few meters away...spdiff?
Rob.

[TheBaronGroog]

Nice work, not wanting to rain on your parade but I have a few Qs:

Why worry about 720p display? As far as I'd heard there's no point in HD images on such a small screen? I stock Alpine, Pioneer, Sony, JVC and Clarion screens and while there are great differences between the marks the picture on the better screens would be damn hard to beat-I know Pioneer and Alpine use WVGA and I really can't fault them.

Why go to the time/expense of what you've done and then use the cheapest speaker cable I have ever seen?! Ihope that it's just for your "test" set up!

Also why not go for a better specified source unit in the 1st place? Alpine or Pioneer would have been my choice over in the UK, with more limited range than in Japan, surely you have a wider range of their products and goodies like Eclipse?

[kotani]

Originally Posted by Bertje

Very nice project (or proto..) As far as I know I2S should be connected with very short wires. If you really have to go a few meters away...spdiff?
Rob.

Originally, I couldn't find space in the front of the car for the dac box, so I thought I would somehow need to extend the I2S lines to the back of the car. Fortunately, I found some space behind the glove box, so the short STP Cat5e cables should do the trick.

Originally Posted by TheBaronGroog

Nice work, not wanting to rain on your parade but I have a few Qs:

Why worry about 720p display? As far as I'd heard there's no point in HD images on such a small screen? I stock Alpine, Pioneer, Sony, JVC and Clarion screens and while there are great differences between the marks the picture on the better screens would be damn hard to beat-I know Pioneer and Alpine use WVGA and I really can't fault them.

First, about the 720p screen and PPI. On a 7in, 16:9 screen, the 1280x720 resolution is about 210 pixels per inch. The standard WVGA used in most navigation units are about 131 pixels per inch. To give you an idea, the iPhone 3GS was about 163 ppi, and the iPhone 4's retina display is about 326 pixels per inch.

Most people can tell the difference between the iPhone 3GS screen and the iPhone 4 screens. I agree that for home use, a small, high PPI screen would not be beneficial, as most people will be too far from the screen to notice. However, in a car's environment, you are only sitting about about a foot and a half from the monitor, you can definitely see a difference.

Also, terrestrial tv in Japan is digitally transfered in 1440x1080. The tuner is built into the unit, and there is a clear difference here as well, especially with the complex Japanese (Chinese based) characters, so there will always be a constant source of HD video for the screen to play.

Also, later on, I would like to add a carputer to the system in the future, and I will be able to send video and audio through the HDMI cable to the unit. While surfing the internet, the higher resolution screen will definitely help. I don't know of any other navigation head unit at the time that will input HDMI.

Originally Posted by TheBaronGroog

Why go to the time/expense of what you've done and then use the cheapest speaker cable I have ever seen?! Ihope that it's just for your "test" set up!

This is just a test setup. I will be using much better speaker cables throughout. (I have it in a reel, and I don't want to cut them up)

Originally Posted by TheBaronGroog

Also why not go for a better specified source unit in the 1st place? Alpine or Pioneer would have been my choice over in the UK, with more limited range than in Japan, surely you have a wider range of their products and goodies like Eclipse?

Pioneer is the other big navigation manufacture in Japan. Alpine is starting to gain a bigger market share, as well as Kenwood for their speed, but the big two are Pioneer and Panasonic.

In terms of navigation sound quality, Pioneer seems to have the best reputation. Even the top of the line pioneer AVIC-VH09CS uses the AKM4388 dac. Most people who are interested in SQ will run a navigation unit and another quality audio head unit at the same time.

Here is an example:


Personally, I don't like having two control units in the car at the same time. Some people are ok with it, but I figure I would go beyond what others are doing, while at the same time, keeping simplicity.

[TheBaronGroog]

Points taken, it's a shame Panasonic have pulled out of the UK as they did have some great products.Nice work

I have to say I'd run the nav through a decent SQ unit-as you pictured-though I use Nav so little I got rid of my AVH-P7500DVD and AVIC-9DVD to get the DEH-P88RS instead-iphone does the nav well enough for my limited use and while the 7500DVD had good processing capabilities it's not a patch on the 88RS. Admitantly it's a shame that no manufacturer has really addressed the need for a media station and SQ source unit in one package-Alpine's PXA-H800 add on is the closest anyone gets!