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[05omegav6]

Starting to plan ahead... Plan was to add a pair of Rca plugs to thie CDC ribbon in order to add an audio input to my NCDC2013 with Bose.

The idea being to connect the amp out puts from a n other headunit in order to expand the system whilst retaining the Bose set up. Is their any reason why I couldn't use the front speaker outputs instead of the amp outputs?

TIA

What are the pros and cons of either approach

[VXL V6]

Starting to plan ahead... Plan was to add a pair of Rca plugs to thie CDC ribbon in order to add an audio input to my NCDC2013 with Bose.

If you wish to retain the CDC then you will need to incorporate a DPDT selector switch to chose the input.

The idea being to connect the amp out puts from a n other headunit in order to expand the system whilst retaining the Bose set up. Is their any reason why I couldn't use the front speaker outputs instead of the amp outputs?

What are the pros and cons of either approach

You will probably encounter impedance issues. The ideal is a line level output from the source - something like the line out connections on a head unit for an external amplifier would be the ideal, anything more will potentially fry the preamp stage on the NCDC.

[05omegav6]

Ok RCA it is from the aux amp output.

CDC functionality isn't a requirement... I have that well and truly covered

[TheBoy]

CDC from TBE is currently mislaid, so I could use gayPod in France. Must remember to mark it as TBE's as it has a good laser

I reckon that gayPods and gayPhones could do with a shade more preamplication first. Some of my cheapo MP3 players are perfect, some are also a tad quiet. So might be worth building a small preamp.

VXL-V6, whats yours like for volume?

[VXL V6]

Volume is fine, I can adjust the line levels slightly on the MP3 player to match radio / cd levels. 

I use ITunes with normalise set to ensure the MP3's are all around the same volume.

[05omegav6]

Having perused this thread...

https://www.drive2.ru/l/288230376153084194/#post

... which details how to connect a 3.5mm jack to an NCDC unit.

I have two questions...

1. In order to add a pair of RCA plugs, I simply tap into wires 1 and 4 for left and right audio respectively. Can I ignore the ground connection. iirc, it's only one wire per plug...

2. Do I need to cut wires 1 and 4 and simply connect to the headunit side (rather than the cdc side obviously ), or can I just tap into them?

I have no intention of using the cdc, but would rather not permanently remove the facility. If the alternative source is switched off, then no reason why the cdc shouldn't function as intended

[zirk]

Having perused this thread...

https://www.drive2.ru/l/288230376153084194/#post

... which details how to connect a 3.5mm jack to an NCDC unit.

I have two questions...

1. In order to add a pair of RCA plugs, I simply tap into wires 1 and 4 for left and right audio respectively. Can I ignore the ground connection. iirc, it's only one wire per plug...

2. Do I need to cut wires 1 and 4 and simply connect to the headunit side (rather than the cdc side obviously ), or can I just tap into them?

I have no intention of using the cdc, but would rather not permanently remove the facility. If the alternative source is switched off, then no reason why the cdc shouldn't function as intended

Bloody hell that guys soldering skills aren't all that.

You will need to use the earth / ground connection where ever required, as apart from being a return signal for the I/p and o/p's its also required for the signal return from your external source, whilst some would argue that its all connected to ground anyway, connecting all the grounds locally at each switched audio point decreases the chances of any long earth loops and the possibility of picking up interference.

As for tapping into the audio line without switching, not a good idea as your effectively adding two output stages together (whether live or not) to the same I/p stage, so your changing the impedance of your external source which may effect frequency response, headroom and signal to noise ratio, plus you also run the risk of adding any residual / quiescent noise from the CDC o/p to your required I/p.

[05omegav6]

Ok, makes some sense... So cut the audio connection to the CDC and isolate it.

Confused by what I am connecting to ground though each Rca lead is single core... No interest in adding a 3.5 mm jack, which I understand why that needs a ground connection

[zirk]

Ok, makes some sense... So cut the audio connection to the CDC and isolate it.

Confused by what I am connecting to ground though each Rca lead is single core... No interest in adding a 3.5 mm jack, which I understand why that needs a ground connection

RCA lead is an unbalanced audio line, inner core is signal (or signal live) and outer (coax braid if you like) is ground / screen / earth (signal return).

Without a signal return, no audio, unless it can find a return through another way, ie, common ground, which was mentioned earlier, earth loops etc.

If your your switching audio signal live locally, ie on a small PCB or using very close proximity switches next to each other, the you can get away with using a common ground, however a signal cable over a longer run, ie switching between different components need to have its own earth screen / ground / signal return, what ever you want to call it.

So your RCA leads will need to be inner and outer core connected, both ends. 

[05omegav6]

Ah ok, so outer sheath gets connected to line 8 in that guide. Presumably both grounds can be connected to a common point

[zirk]

Ah ok, so outer sheath gets connected to line 8 in that guide. Presumably both grounds can be connected to a common point

Yep, pin 8 is the Signal ground (its also earth but runs along the L and R live signal leads, in this case its not screened, as its a ribbon cable, but its ok for a short local run, its there to serve as a direct signal return feed, so the L and R signal doesn't have to find the feed through other earth source, ie another ground on a PCB or neg volts somewhere etc.)

So, in your case the two RCA leads (screened cables) the outer screened braid of both leads gets connected together to pin 8, at the other ends the RCA connector does this for you, ie, connects the ground, signal return at the nearest point to the signal live (inner) output connector on your external source.

[05omegav6]

Ok, so three connections to make on the ribbon, and leave the CDC side of the audio insulated and disconnected...

[zirk]

Ok, so three connections to make on the ribbon, and leave the CDC side of the audio insulated and disconnected...

yep, diss the L and R signal from the CDC, you can leave the pin 8 / ground lead as is, just join your screen cables to it.

[zirk]

Just to add Al (and maybe confuse the issue) I done a few of these, the last one being a few years back now, on the last one I did I added some present pots to the line in, reason being as different phones, MP3 players seemed to vary with there output levels, once the chosen device was found, in my case a Nokia, I adjusted the pots so as to allow the best level on the phone, ie, max phone vol equates to max HU vol, that way you making the best of the phones output headroom and dynamic range to the HU's input.

I also added a couple of capacitors on the inputs just in case there was any stray DC levels kicking around, but not the end of the world if there not added.

[05omegav6]

Confused dear? Me dear? No dear. I don't know what you could possibly mean...

Will use the amp outputs from aux headunit, so aux levels will be controlled/adjustable from the menu on the aux h/u... The Bose amp should then take care of the rest