L8r

Repost - for some reason I was logged on as Ibleedgarnet, no idea how or why, but here it is again.

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Long time, lurker, first time poster. I was inspired by the system that OverLOAD described, but too cheap to get the tape deck. So I got the belkin ipod car charger (with the pre-amp) and then wired directly to the CD player. It was very simple, (after the instructions for removing the head unit that is =) ) and now I just put a regular CD into the player and as long as my ipod is plugged in, the ipod owns the channel, when I unplug it, it is CD's as normal. I ran the line out under the center and back to the charger plug in the center "glove box" - it works great and sounds SO much better than the iTrip or other FM solutions. - Great job OverLOAD - and just to let everyone know, you can do it with just the stock equipment.

John Blakely

miata2rx8

this is very cool news. So, here is what I am interested in: tape hack for XM radio, cd hack for IPOD. Has anyone done BOTH of these hacks?

OverLOAD

hey L8r,

I'd like to hear about more details about how you spliced in that ipod car charger. It's just a line-out connection from the ipod right?

How about some details on exactly how you wired it up?

Cool beans,

OverLOAD

L8r

I actually just added a line out to the CD player - happened to hook it to my iPod, but I am sure it will work with other devices as well. I got an XM commander for christmas, so I will keep the forum up to date (with pictures this time) about my installation of that device. I wish I had taken picutres as I went through, but here is a rough outline.

I removed the head unit completely, took it into my garage and disassembled it completely, down to the circuit boards (you do not have to do this - I was simply exploring =) ). Then I discovered there is a small PC board that connects the head unit to the CD player. I removed that board and then found the input channels and a ground. I purchased and 8 foot shielded 1/8" stereo extention cable from radio shack, cut off the female end of the cable, then tinned and soldered the appropriate wires to the pads I identified on the PC board. Once that was done, I routed the 8 foot cable our of the head unit, reassembled the unit and reinstalled into the vehicle. Then I lifted the center, routed the cable through to the power socket in the center console, and drilled a hole, so I could have a line out to the head unit. I then bought the belkin ipod charger (which has an 1/8" plug into a pre-amp on the charger) plugged that in, selected CD and was in business. I have attached a picuture of the final result. I will take more as I attempt to install my XM Commander this weekend. Also, I have not had any interference issues that have been mentioned in prior discussions. Hope this helps.

l8r


With Ipod in (that little mark on the iPod is a protective cover doing its job =) )




With Ipod Out


so I just added that 1/8" mini stereo out that plugs into the CD player. The holder BTW is by belkin as well and fits into a cupholder. Yes I can shut the comparment without any problems.

ectomort

Can you post any pictures, or more detail about which leads you used for Left channel, Right channel and GND?

I'd like to pull off this mod as well.

OverLOAD

Presumably, there is a pre-amp board in the CD unit, much the same way that there is in the Tape unit?

What makes me curious, is how it 'automatically' bypasses the audio of the CD.. or are you using a CD that's full of "Silence"?


FYI,

My partner and I are considering making a module which will plug into the CD expansion module (for the Tape or MD player) and provide optical, SPDIF and other input formats, as well as a serial port to connect into a computer with Winamp based controls..

Ideally much cheaper, doesn't involve soldering, perfect sound quality, and usable steering wheel controls for Winamp in a mini car PC.. Probably selling in the neighbourhood of $50.. if there's a lot of interested people, please say so, and we will step it up a notch. right now we're just contemplating the idea.

Happy Holidays!


OverLOAD

mdmaclean

I'd be interested, as long as the final result had a high quality appearance. Are you planning to have all these jacks on the console of the car (where the MD player would be)? If you do, it might look a bit cluttered.

ectomort

I'd definitely be interested in such a module (especially if it worked well with iPod.)

"Show us the meaning of haste!"

eXentric

OVERLOAD,

If you've already figured this all out, I'd gladly pay you $50 or more for it.

I'd prefer a USB connection then a serial connection, but I understand it's quite a bit more work to pull this off.

Can you start a new thread and/or elaborate on what this module would be capible of? I'm assuming its tapping the bus + / - pins we've seen for monitoring the steering wheel controls? What else have you been able to determine is available over this bus (if in fact you have gone this route)? Can you, for example, write to the display screen?

What other progress have you made so far on this? Have you managed to trick the head unit into thinking you have a tape module (or any other module) in the tape bay? I have you managed to get audio through the tape bay without the the Mazda tape player? Any other information you can share would be great.

Thanks, and good job!!!

M6Ray

Hi OverLOAD,

Great work and contribution to the forum. I enthusiastically third the notion for your proposal for a $50 add-on module.

It seems like a great idea if you can pull it off. 1/8" stereo, and optical inputs are good ideas as that would cover most of our AUX input needs. A usb connection would be a nice alternative to serial.

Question: Would this module's faceplace use the existing spot for the cassette player/ md player?

Thanks for the effort and keep us posted!

:D

OverLOAD

The customized unit has had it's own thread started, and is here:

https://www.rx8club.com/showthread.p...threadid=17396

miata2rx8

l8r-

on the right side of the board that connects the CD to the headunit, there is the L, SGND, and R solder points- these seem the only likely candidates- is this what you used?

OverLOAD

close a similar thing on the tape module, but there was no gound labeled.

OverLOAD

L8r

miata2rx8 -

yes the labels were in black as I recall, - also the ground was "below" the other pads on the board forming a small triangle. (it is a rotary after all =) ) the SGND is for signal ground - you should also do a continuity check beofre doing any soldering.

L8r

miata2rx8

sorry to ask so many questions; my solder points seem very clean, not much solder, no dripping or spillage, however the sound quality is VERY low and of very bad quality. What does this suggest- what should I look for? I am thinking of wrapping the wires with shrinkable wrap up the pad- right now they are between 1-2 mm of exposed wire.

OverLOAD

Several possibilities:
1. your audio input level is too low or high. Try adjusting the level of your source device to find the ideal level

2. you've got a ground loop causing interference. If you can run the device on battery power only (car-not-running) and the noise goes away, that's the problem. A ground loop isolator will fix that, but may be expensive, and/or hard to find. Radio Shack will usually carry them

3. you've somehow messed up the wiring and connected a signal to the gound and a ground to the signal. Recheck your wiring to make sure that your wires are going to the right places. This would likely sound like there was just something wrong with the setup.

Check it out, maybe it'll be ok. Also, try using a different audio source device (like a portable cd-player) to see if it works with that any better..

Regards,

OverLOAD

ectomort

I got tired of waiting, and didn't want to rely on the cassette module, so I opened up the headunit itself and patched in to the CD output channels. (Kudos to OverLOAD, l8r and others for their valuable information.)

It wasn't too risky or hard (some simple soldering), it doesn't require any additional modules, cost about $10 (for the minijack extension.) The technique will work for either the Bose or base head units.

The result: seemless integration and perfect sound from my iPod. Next, I plan to figure out how to pass the steering wheel controls to the iPod's wired remote input.

I'll post more info on what I did if anyone is interested.

MrWigggles

Please post the info.

As an electrical engineer who does a lot of circuit design and testing, I would recommend that just trying to inject a signal into a signal stream isn't the best of ideas.

Sometimes it will work fine other times you might damage something or get poor results; it really depends on your MP3 player and its output impedance. The iPod is probably robust enough in design to not cause any problems but other MP3 players might not like the forced mixing connection.

Please show us what you did. (detailed shots of the ciruit board would be nice with part numbers. I'll try to make some comments on them.

Thanks in advance.

-Mr. Wigggles

OverLOAD

That reason, in particular is why the tape module hack doesn't sound as clean as it could. If you connect into the expansion connector, you might be able to get a better signal, but it's the same thing, the module has to be completely disabled from it's original function, and doesn't work the way it used to.

Ectomort, It sounds like you've got decent results, but I'll bet if you disconnected the audio outputs (cut the CD audio source traces) at the point before you tapped in, you'd get even better sound, at the expense of loosing a functional CD module, then you could play any CD, and the source wouldn't mux into the stream

It could be dangerous to the head unit if you pumped up the volume too much though.. be careful.

Still working on a Plug and Play solution which integrates with the radio.... and getting closer.....

OverLOAD

ectomort

Here's a description of how I patched an auxiliary line-in to the head unit. I have the Bose head unit, but I'd be surprised if this approach doesn't work for the base unit, too.

Follow the standard instructions (posted elsewhere on this forum) to remove the audio assembly from the car and separate it from the control-trim panel.

This picture shows the audio assembly from below (the lower module is empty.)



Turn the unit over. Detach and remove the upper module (CD/MP3/CD6 player) from the assembly.



Remove CD module front plate (thing with the black felt dust guard) according to the instructions printed on the top of the CD module.
To expose the head unit circuit board:[list=1]
[*]remove 2 3mm short phillips screws from front of unit
[*]remove 2 5mm screws from bottom of unit
[*]remove 2 5mm screws from rear of unit (back plate will come off now)[/list=1]

Gently pry off the head unit cover plate to expose circuit board and remove the right (on the left in the photo) side plate to expose CD-head unit PC board.



On the left side (not visible in this picture) is a little board which connects signals from the CD module connector to the head unit's main board.

I'm sorry the next picture isn't clearer, but it shows a closeup of the head unit from the left side, the green board connects the CD module connector to the main head unit circuit board. (You can see a portion of the pink sticker in this photo that also appears in other images I've posted.)

I've added a diagram which shows the various lines (labeled as they were printed on the board.) I've marked the locations where I patched in in green. There are no electronic components on the board, so it's relatively safe to solder there without risk or heat-damage to components on the head unit itself.



I purchased a stereo minijack extension cord and snipped off one end, leaving the male plug end to connect to the line out from my iPod. Then, I threaded the cord through the hole in the frame near the pink tape. (It's important to use this location, so that the cord is not crimped when the audio assembly is re-installed in the car.)

Next, I prepared the end of the cord, stripped and tinned the wires, and used the continuity test function on my digital multimeter to identify the left and right channel and ground wires. (On a stereo mini-jack, the tip is left channel, middle is right, and the base is the ground.) Then I soldered the cord as shown above and used the continuity tester to verify a good connection between the male end of the mini-jack and the corresponding lines going into the main circuit board. It's a shame the picture of the final solder job didn't turn out.

I then reassembled everything. Here's a picture of the nearly complete assembly showing the patch cord.



And here is the iPod in the car. I use a Monster Ultra-Low Profile Charger for iPod™ with Dock Connection (http://www.monstercable.com/computer...r.asp?pin=2132) which gets power from the accessory outlet and attaches to the iPod's docking port. It provides line level output which the patch cord plugs into. There's no risk of blowing to the head unit with the signal, since the iPod's volume control doesn't affect the line output. The adaptor includes a voltage inverter, so there isn't any noise from ground looping. I get perfect sound.

The patch signal source merges with the CD player source, and the head unit won't accept input from the CD player unless it's playing a CD, I've burned an audio CD which contains nothing but silence (I call it 4'33" extended remix, a tribute to John Cage.) When that CD plays, the iPod effectively owns the audio channel. The CD player auto repeats, so every 80 min or so I have to tolerate a 2 second dropout while CD cycles. Since my iPod has over 7200 songs on it, I won't often need to pop in a normal audio CD, but as long as I turn of the iPod, there's no problem.

ectomort

I'm a software engineer with a bit of EE background. I didn't check on the input impedances, but since I'm dealing with a line level signal from the Monster adapter, and the results sound so good, I doubt there's any problem w/ my set up.

ectomort

As I posted above, the signal is line level (from the iPod's dock connector.) Should I plug into the iPod's headphone jack, I would have to be concerned with pumping too much signal through.

I use a "silent" cd to ensure only iPod is supplying audio.

I remain appreciative of your efforts to bring a custom module to market, since there are obviously many folks who won't want to open up their HU and tap it like I did. I just ran out of patience and decided to experiment a little.

yanksfan_98

FWIW:
A more significant consequence of this method is that you are now exposing your head unit to static electricity. Usually inputs like this would be properly ESD protected.

Admittedly, I don't know how the car would handle this, since the car isn't grounded anyway. And not that I have ever seen anything damaged by ESD, but i sure have been zapped while I was wearing a wool sweater.

speedmaster

First of all, congratulations for an ingenious and easy to be done solution albeit costly...

How is your sound quality? I've just installed my deck one day before you passed this instructions and I'm somewhat unahppy with the flat sound I'm getting from my IPOD. I have the same setup in my wife's Stratus and the sound is much better... I've even exchanged the whole setup IPOD+tape adapter (one each time and then both altogether) and the result didn't change. The Mazda tape head has far less treble than the one in the Stratus

I hope it is due to the head quality and that bypassing it will give better results. On the flip side if the whole circuit is built taking into consideration that the frequency response of the tape head is limited than it won't make any difference...

Would you let me know what do you think comparing the sound with a tape adapter and the direct connection you cleverly designed and implemented.

Thanks.....

OverLOAD

You can get near-CD quality sound, if you want to sacrifice ever using the tape module to play tapes again. It's not really that difficult, (if you've done some soldering before) but you have to completely disconnect the audio sources from the factory RX-8 connector, and feed your audio source directly into the HU. IT's possible to overload the circuit and blow the HU tho, so it's pretty risky.

I'm thinking about doing a small write-up next time I take my tape module out so that I can explain the process better. It's really very similar to what ectomort has done with his CD module.

Regards,

OverLOAD