AUX Quiet?

[FunkyGBrown]

Up to now I've been using one of these AliExpress FM transmitters for music.. it's ok but the sound seems lacking.

Decided to try a usb c - AUX cable but the sound is so quiet and doesn't sound like it's coming from all speakers.

Issue with the aux connector perhaps? All the speakers definitely work, the cable seems fine.. I've had the stereo out and it all looks connected fine.

Anyone come across this before?

 

[smorris_12]

Obvious one, is the volume up on the phone?

 

[FunkyGBrown]

Obvious one, is the volume up on the phone?

Yes, should have mentioned.. checked that and the cables were in tight, just doesn't feel like I'm getting sound from all the speakers.

 

[M1k3yC]

Anyone come across this before?

Yes. I used to own an E86 and the aux in was quieter than the other sources. Sounded fine, though. I just had to remember to turn the volume down before switching to another input source.

 

[E86]

Have you checked the Aux Level setting on the radio?

With the Aux input selected, press the button with the music note on it, it cycles through Bass / Treble / etc. then Aux Level 1-5.

 

[FunkyGBrown]

Have you checked the Aux Level setting on the radio?

With the Aux input selected, press the button with the music note on it, it cycles through Bass / Treble / etc. then Aux Level 1-5.

Hmm I don't seem to have that option.. I've got bass, treble, FAD, BAL and an option called TONE LIN?

No level it seems..

 

[Matty_Z4]

Do you have a link to the USB-C aux cable you bought? It sounds like the cable is outputting at headphone level and not line level if this is the case you will need a new cable that outputs line level.

Not sure what can be done in the case other than a new cable, Sometimes there is a switch on the device that changes between Line Out and Headphones Out sometimes it switches automatically (DSP Detects the signal voltage)

One thing to do in order to confirm its your USBC - Aux cable is if you have an analogue device or an old phone where you can use a normal 3.5mm -> 3.5mm cable and test with that. If the Analogue device works fine then that confirms its your converter cable.


https://geekmusician.com/line-out-vs-headphone-out/

 

[brillomaster]

still a thing... for some reason, BMW put a resister in the aux line so its always way quieter. whenever i listen to my mp3 via the aux in i have to turn the volume way up. and then when i switch back to the radio i get deafened. its somewhat annoying to be honest!

do you have bmw professional audio? in which case this might help:

https://www.youtube.com/watch?v=uz4x1qsmO9E

 

[smorris_12]

The problem in a lot of cases is disagreement about what constitutes a full volume line signal. Many devices use 1v pk-pk while some (and I think this includes BMW) use 2v pk-pk.

The reason is long, boring and maths-y.

 

[Matty_Z4]

still a thing... for some reason, BMW put a resister in the aux line so its always way quieter. whenever i listen to my mp3 via the aux in i have to turn the volume way up. and then when i switch back to the radio i get deafened. its somewhat annoying to be honest!

Its a 300kOhm resistor across Left and Right channels, this is how the radio detects that there is an AUX cable connected to it and makes it available in the mode menu. There is also a couple of 22uf capacitors in series with the Left and Right channels for noise suppression. Both the capacitors and the resistor will have some effect on the signal (Will reduce the gain) but shouldn't make such a dramatic difference unless the signal from your device is already weak.


1Volt Peak to Peak will be headphone level and 2v peak to peak will be line level.

I wonder if there is an input gain adjustment on the head unit that can be used to adjust the amount of attenuation on thee aux input. On pro audio gear there is normally a gain adjuster screw on the back of an amp or its done in the software on the DSP. Not sure how to translate pro audio into car audio.

 

[smorris_12]

As someone who recently dismantled their standard radio to do aggravating things to it at component level, nope, no adjustment. The signal path just follows straight through to the amplifier chip (TDA 7385) which has a 2v pk-pk spec on its inputs.

 

[Matty_Z4]

As someone who recently dismantled their standard radio to do aggravating things to it at component level, nope, no adjustment. The signal path just follows straight through to the amplifier chip (TDA 7385) which has a 2v pk-pk spec on its inputs.

Well thats a bit of a s**t then I guess the only option is to get a USB-C to 3.5mm cable that outputs at a higher voltage or use Bluetooth.

 

[smorris_12]

Just to pour more cold water on, I've always found Bluetooth outputs to be aggravatingly low too. I've got a TP-Link one in the Zed and, with my old phone, it was hopeless. This was what got me into looking at signal levels. With my old phone it maxed out at 0.7v pk-pk. My new phone is louder over the same hardware which is ridiculous as that's entirely a software thing.

 

[FunkyGBrown]

Just to pour more cold water on, I've always found Bluetooth outputs to be aggravatingly low too. I've got a TP-Link one in the Zed and, with my old phone, it was hopeless. This was what got me into looking at signal levels. With my old phone it maxed out at 0.7v pk-pk. My new phone is louder over the same hardware which is ridiculous as that's entirely a software thing.

I found that a bluetooth adaptor on battery was very quiet (Same as the AUX is, exactly). However, plugging it in via the cigarette lighter gave a full range of sound, BUT there was excessive interference. I did try a portable battery to power it, but it was back to being quiet.

So possibly it's dependant on the input signal, as you say.