My C33 Stereo Aux Input Project

[flyfishvt]

If you look at the second pic in the original post you'll see the Tape Output board. In the actual unit it's under a thin metal shield. Remove the shield and solder onto the board just like he did.

Once everything is installed you fool the player into thinking there is a tape in it. Then you can use the buttons on the unit to switch from cd to tape to radio. The only difference is when you switch it to "tape" it will use the input from you mp3 player or whatever you have plugged into the aux port. If you decide to actually put a bank tape in it will still work but you'll hear the clicking of the tape spinning and sound quality will be reduced.

[NJDave]

"If you look at the second pic in the original post you'll see the Tape Output board ..."

Got it ... but did you hook wiring up to the top Tape Output Board, or the Head Unit "In" terminals on the side board?

Previously, I had hooked up to the "top" Tape Output Board terminals only, and the result was a "muddled" sound, coming out of both channels ... really bad sound. Like "m2pc" I would prefer to hook-up through the main board TDA processor chip, as the sound should be 100% clean going into the Tape Player Head unit this way, instead of taping into the tape circuit board.

How's the overall sound on your hook-up?

[flyfishvt]

I hooked onto the tape out terminals. The same ones as the top set of wires in that pic. Sound quality is excellent. After reading this thread and others I was prepared for poor sound but it's excellent. I don't know if it makes any difference but he used RCA ports on the back. I used a headphone jack similar to what he installed on the front.

[NJDave]

I hooked onto the tape out terminals. The same ones as the top set of wires in that pic. Sound quality is excellent. After reading this thread and others I was prepared for poor sound but it's excellent. I don't know if it makes any difference but he used RCA ports on the back. I used a headphone jack similar to what he installed on the front.

In my hook-up attempt, that didn't sound great, I used a headphone jack too (but I'm sure that wasn't
the problem).

Did you use "shielded" 3 wire cable (off the tape head board terminals, or did you just use single individual
wiring (ie: covered 18-22 gauge)?

I may try re-soldering a new set of wires to the tape circuit board again, as I took everything apart, and
will need to try this all over again.

I'm thinking it might make more sense to "patch-in" through the "head unit in" side terminals shown in the photo.
This way the audio would be by-passing some of the tape board circuitry ... and making a more direct connection
to the main processor. Or it doesn't really matter, because both the top and side terminals are directly connected
to each other, and are "all-in-the-same"

Did you ever try the wiring just "patched-in" to the side board terminals (instead of the top ones like you have)?

[flyfishvt]

I just used plain covered wires. I grounded it to the chassis of the head unit instead of soldering the ground wire onto the board. Not that it really makes any difference. It was just easier that way. If you have some phone cable that works good too. Not the white thin stuff that plugs into the back of the phone but the round grey stuff with 4 wires inside. The wires are very small and easy to solder.

[NJDave]

So I just re-soldered the three wires to the three terminals off the main tape head circuit board (the small board one on top of the separate tape drive mechanism, with the tape out solder termainals), and tried the deck out with an iPod Touch attached .... the sound ONCE AGAIN (this being my second attempt), SOUNDED LIKE CRAP!

The sound, tapping into the tape deck circuit board is kind of "scratchy" and sounds like the speakers are being overloaded or something ... definitely not a clear sound output by any means.

"flyfishvt" ... I'm not sure what you meant by "Then you can use the buttons on the unit to switch from cd to tape to radio."
I'm doing this Cassette AUX modify with a BMW C33 Cassette/Radio unit, and the tape player only becomes active (takes over from the radio or 6 CD player in the trunk), when a tape is placed in it ... there are no "buttons" (My older C33 BMW Cassette player is out of a 1997 E39 528i).

I still haven't figured out how to tape into the "audio processor chip" on the main board, like the "m2pc" claimed to have done. I just wish he would repost his method in a full understandable "step by step" description.

Come-on "m2pc" what ever happened with getting back to us on this!



*Note: When I re-hookup my in-dash BMW Business CD player, and use the iPod Touch in the AUX mode .... the sound is awesome ... so it's not my speakers or anything that are making the older BMW Cassette player sound like crap. It's the non-working method of using the Cassette tape circuit for the AUX output.

[flyfishvt]

I just finished a 6hour drive yesterday and the sound quality from my aux input was as good as the CD player. Don't take this the wrong way but are you using a "stereo" cable? I almost bought a mono cable to use as an extension cable. I also don't know what you have for wiring or connectors. I used plain wires (non shielded) for the ones inside the headunit. I used a plain (cheap) female recepticle from radio shack. I drilled a hole in the back of the headunit and mounted it there. Then I ran an actual headphone extension cable from there to the center console. One end of this extension cable was male and the other female. I mounted it to the under side of the center console and used a 4' male-to-male headphone cord from my i-phone to the jack. Just like you...I soldered onto the small board on the tape deck. I'm no expert on sound systems but crackling sounds are usually a bad connection or static caused by a bad ground or something like that. Instead of grounding from the female recepticle to small board I grounded directly from the recepticle to the chassis. What kind of plugs and receptilces are you using?

As far as using the buttons to control everything...its easy. While the cover is off the headunit and its turned on you manually push in on the tab that an actual tape would hit when its inserted. This will make the tape deck think a tape is inserted and it will pull pull it in then the tape carrier will hit the "tape inserted" microswitch in the back. Your deck/headunit now thinks an actual tape is inserted and you can use the tape/cd button to go back and forth from your aux input to the CD player in the trunk if you have one. I did it this way because those fake tapes with the cord on them make a ton of noise as the drive motor spins. With no actual tape inserted it whisper quiet. You only have to do it once. Even if you remove the headunit from the car the tape player stays in what I call "tape locked in" position. If you hit the tape eject button you'll have to reach inside the tape player and carefully push in on that tab again to make it pull the nonexistant tape in and lock down.

[NJDave]

"... are you using a "stereo" cable? ... I also don't know what you have for wiring or connectors. ... What kind of plugs and receptilces are you using?

Q:
Are you using a "stereo" cable?

A:
I have been using a direct 30 pin connector to male stereo 1/8" mini
jack (a P.I.E. Universal cable, that is connected to a Radioshack 1/8"
female panel mount on the back of the C33 Cassette deck (I drilled a hole
in the heat sink and mounted the female jack to an aluminum extension
wall I soldered to the chassis, behind the "holed" heat sink opening).

__________________________________________________ _______________

I'm just wondering if you are connecting the iPhone from the internal headphone jack, or using a 30 pin connector coming off the bottom of the phone?


I may try grounding the new wiring ground to the chassis itself, but I would think the ground terminal on the Radioshack jack would be enough to accomplish a good ground.

I don't have a direct stereo male to male 1/8" cable to test if this would be a better way to connect ... rather than the 30 pin outlet. There may be something to the fact that the direct 30 pin connector may be sending a more pure unprocessed signal to the deck, and over-loading the AUX input signal (although this shouldn't really happen), as opposed to using the internal headphone jack of the iPhone/iPod Touch .... where the signal is coming from a digital signal processor that control the "processed equalizer" setting outputs.

I'll have to get a male to male connector cable and try the headphone jack off the iPod Touch ... and see if that is any better for sound.

[flyfishvt]

I wouldn't even know where to begin with a setup like you have. I kept it simple. I use the headphone jack on my I-phone. I've also tried it with a mp3 player I have and it works with that too.

[NJDave]

My understanding is that the audio output on the iPod & iPhone 30 pin dock connector, is that it is a "fixed" line level output, and it also can't be controlled using the volume setting on the iPod/iPhone (only the MID unit volume knob works with the 30 pin dock connector). Only the headphone jack audio output is controlled using the volume setting, directly off the iPod/iPhone.

So I'm thinking, this so-called 30 pin dock connector "fixed line level output", of the iPod/iPhone, may just be too much sound output level for the tape circuit to handle ... and some how it's distorting the input signal to the re-wired tape circuit AUX output I've done.

I get back with my results, when I've had an opportunity to just run the line from a headphone stereo jack, on an iPod Touch, to the AUX input jack.

[M3C]

That solution has been used for years through an interface like Dice or Dension. You can get an extra module that even makes you switch between the original changer or the aux channel.

Are you saying that with Dice or Dension interface you can still use the original CD changer or the interface just by switching? Switching - plug unplug or with a switch?

[TheGuy34]

Hey m2pc what ever happened with the direct to processor approach? I cant get good quality out of the soldering to tape deck technique.

[NJDave]

To follow up on my final C33 AUX conversion observations.
Probably a little late, but better late than ...


In following up on my AUX conversion of the BMW C33 Tape/Radio Cassette Player, I was actually able to confirm having the unit work through wiring to the tape head inputs on the lower circuit board. I was also able to confirm that using the Apple "earphone" jack (on my iPod Touch), was the better connection method to use, rather than connecting through the lower 30 pin connector port.

In using a standard 1/8" stereo cable, coming out of the iPod Touch "earphone" jack and connecting to the C33 "modified" AUX input jack, I was able to have the C33 AUX modification work perfectly. The sound is great, and pretty much matches CD quality (that of course considering coming from an mp3 player - iPod Touch). I also found that in using the iPod Touch "earphone" jack output, I was also able to adjust the sound quality using the internal iPod Touch Apple (EQ) equalizer settings (reduce bass, increase bass, rock, flat, acoustic, loudness, treble booster, etc.). This way, the sound output could be almost "custom set" for various sound listening/car interior situations.

With using a "blank tape" in the cassette deck, when using the AUX input, I didn't notice any real objectionable tape deck/tape noise, except the occasional tape "auto A-B side flip" (but using a long play tape of 60 minutes or more helps in this area). Also, with the BMW outer C33 "cover door" closed, there wasn't really any issue with tape noise.

Over all, this C33 AUX conversion turned out very well, and the sound quality was excellent, obviously, depending on the overall quality of your speakers and using high quality mp3 audio files of 256-320 VBR (typical lower quality mp3 audio files (128 kbps or lower) will obviously not produce sound of a higher quality).

[m2pc]

Hey m2pc what ever happened with the direct to processor approach? I cant get good quality out of the soldering to tape deck technique.

It works fine for my setup, EXCEPT:

1) I had originally planned (and built) an auto-switching circuit using an op-amp and some relays, but it never got wired correctly and doesn't work unless the car is not running (key in "ACC" position). This was intended to detect and automatically switch the audio signal from the external device into the audio path of the C33/C43, directly to the TDAxxxx audio processor. When the AUX signal was paused or disconnected for a certain number of seconds, the relays would fall back to their default state, thus allowing the normal stereo operation.
2) As a result of #1 not working, my head unit is in permanent "AUX" mode. Meaning I have to launch an Internet radio app on my iPhone if I want to listen to any local AM/FM stations.
3) Due to #2, when the cable is unplugged from my iPhone, I get a TON of engine whine/noise in the system.

When connected to a good audio source, however, the sound quality is excellent!

[flyman3456]

Look an empty post....

Look an empty post....

And now that I have 15 posts...

So I originally followed the diy aux install and had soldered my connections to the tape board. This resulted in really poor sound quality. Following some of the info posted in this thread I was able to make a direct connection to the TDA7328. Pins 10 and 14 are for the tape input. 13 and 9 are the CD input. Also, this method disables the ability to play tapes. (although it only takes 20 minutes to revert back)
Tools required:
- A decent soldering iron, tip cleaner, and solder (i used a $20 radioshack)
- Wire
- Heat shrink tubing
- RCA and 1/8 inch plugs or your choice
- 2 x 2.2 microfarad capicitors http://www.radioshack.com/product/in...tent=CT2032230

I now have an aux input that sounds just as good as the cd input.

Hopefully these pictures provide enough explanation.













Reference the TDA7328 datasheet. http://www.datasheetcatalog.org/data...ics/mXytuz.pdf

[405style]

yeah i just use a tape adaptor for the oem look. Sub takes care of the lows, highs are fine on tape adaptor.

[TheGuy34]

So I originally followed the diy aux install and had soldered my connections to the tape board. This resulted in really poor sound quality. Following some of the info posted in this thread I was able to make a direct connection to the TDA7328. Pins 10 and 14 are for the tape input. 13 and 9 are the CD input. Also, this method disables the ability to play tapes. (although it only takes 20 minutes to revert back)

Hey it looks good! I can't stand the soldering to the tape board technique. Ive done it and re-done it like 5 times and it just sounds terrible. I cant put my phone above 50% volume and I have to turn the radio all the way up, then it just qets all fuzzy. Anyway, I just have a few questions.

1) How do you use the input? ie; put a blank tape in?
2) In the picture, is red positive, green negative, and black ground?

Thanks,
Brian

[Surfin]

It works fine for my setup, EXCEPT:

1) I had originally planned (and built) an auto-switching circuit using an op-amp and some relays, but it never got wired correctly and doesn't work unless the car is not running (key in "ACC" position). This was intended to detect and automatically switch the audio signal from the external device into the audio path of the C33/C43, directly to the TDAxxxx audio processor. When the AUX signal was paused or disconnected for a certain number of seconds, the relays would fall back to their default state, thus allowing the normal stereo operation.
2) As a result of #1 not working, my head unit is in permanent "AUX" mode. Meaning I have to launch an Internet radio app on my iPhone if I want to listen to any local AM/FM stations.
3) Due to #2, when the cable is unplugged from my iPhone, I get a TON of engine whine/noise in the system.

When connected to a good audio source, however, the sound quality is excellent!

Bringing the thread back from dead...

So this method would alow me to use the C33 unit with the entire tape assembly/drive off, always in Aux mode, is this correct?
If that's the case, now we have the definitive solution HERE !!

I already have all the parts, just need to confirm before the soldering starts. My plan is to remove the entire Tape unit and install this module just behind the tape door, when not in use (without a flash drive) is looks 100% OEM. With a USB unit, the door stays open and we can use the remote to operate the module, cicle between sources (including FM, just need an extension from external radio antenna), change music and all.

[Surfin]

Update:

I removed the Tape drive and wired the mp3 module directly to the TDA, but as soon as the unit displays "Tape Error" the sound is muted.
With the tape deck on I get sound, but this way I don't have space for the module.
Sound quality was excellent in both tests.

I also considered removing all tape deck parts and leave just the tape mainboard, but this don't guarantee that I will not get the tape error again. The tape deck works perfectly, I think it's not worth the risk, plus I would risk loosing this partial working (as I would have no more tape)

Any tip in about bypass the tape drive ok check?

For now it looks like this:

[Lukitas]

So right now i am tapped to the Cassette player should i do what flyman did? will i get better sound from there or should i just leave it how it is in the tape inputs.

[Surfin]

I soldered directly to the board using capacitors, sound was very good.
But because I could not fit the mp3 module inside the stereo unit without removing the cassette assembly (removing it causes TAPE ERROR and no sound output), I droped the project and got the specific mp3 module for the C33, C34 and CD43, that goes attached to the cd changer port, works perfect.
Looks like this one: http://image.made-in-china.com/43f34...0LT-X3-X5-.jpg
But it's not this brand nor have bluetooth. I liked and recommend.

[Fix.a.ZX]

I soldered directly to the board using capacitors, sound was very good.
But because I could not fit the mp3 module inside the stereo unit without removing the cassette assembly (removing it causes TAPE ERROR and no sound output), I droped the project and got the specific mp3 module for the C33, C34 and CD43, that goes attached to the cd changer port, works perfect.
Looks like this one: http://image.made-in-china.com/43f34...0LT-X3-X5-.jpg
But it's not this brand nor have bluetooth. I liked and recommend.

Hey you were onto something, but the reason you weren't successful in removing the tape deck without error is because the radio expect certain trigger points to be open or closed circuit in order for the tape mechanism to work. Now those triggers are in form of micro switches throughout the tape mechanism. remove the entire circuit out from the tape mechanism (the flex board circuit) and as you are doing so, glue all of the micro switches and hall sensors you find in their resting position (the hall sensor is on the bottom gears, you might need to glue that gear onto the sensor in a certain position). I've not done this fully as I'm not so obsessed with the factory radio but I have gone so far as to open a radio and do it on a test bench.

good luck

[Lukitas]

Hey you were onto something, but the reason you weren't successful in removing the tape deck without error is because the radio expect certain trigger points to be open or closed circuit in order for the tape mechanism to work. Now those triggers are in form of micro switches throughout the tape mechanism. remove the entire circuit out from the tape mechanism (the flex board circuit) and as you are doing so, glue all of the micro switches and hall sensors you find in their resting position (the hall sensor is on the bottom gears, you might need to glue that gear onto the sensor in a certain position). I've not done this fully as I'm not so obsessed with the factory radio but I have gone so far as to open a radio and do it on a test bench.

good luck

Can you do a quick DIY showing what needs to be removed to be able to delete the cassette module please.

[jcinlaca]

Flyman3456,

Did you find a way to "trick mod" the tape player?

[Surfin]

No, I use now a mp3 module that goes at the cd-changer input, fully controlable from the tape deck, problem solved!
Just check eBay for "e36 mp3 module", ranges from $55 to $70, some also have bluetooth.

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