audio interface with bluetooth transmitter

F

Fluxia

Member
Hello I am recenlty finished building a midi controller to control NI Traktor 3.
I am using Trktor with my laptop and bluetooth speaker. In order to use the tracks cue monitoring, I now need to have an additional audio output.
I am considering building an audio interface that has four outputs (2 stereo outputs) and that is capable of trasmitting via bluetooth.
I have built several midi controller with teensy 2 but never anything handling audio. I would like some guidance please as I am a bit unsure whether this is worht it in terms of cost. (I believe I need a teensy 4.1 and audio shield and this is approx £50; a 2 input - 4 output Behringer costs approx £80, but requires a bluetooth trasmitter).
If I build it with teensy I am not sure what other components I need, apart from the obvious jack connectors.
I believe that the Audio System Design Tool should make the coding part fairly easy. In terms of my knowledge in electronic is quite basic, as I said I have only built midi controllers...
Any advice / guidance please?
 
Not sure if I understand your setup. Why exactly is bluetooth needed here? You have your controller in front of your laptop and need one stereo-output as main-output of the the audio software plus a second stereo output to listen over your headphones, right? Is it really necessary to go over bluetooth for both outputs?

One audio shield can handle 2 audio channels (inputs and outputs), i.e. for 4 channels (2x stereo) you would need 2 audio shields. This is possible to build with a Teensy 4.0. For 2 channel audio there is a direct way to use USB-Audio. For more channels there exist only experimental setups as far as I know. This would be one thing to solve. The other thing is to get two bluetooth transmitters to the outputs. This would be the same when using a readily available USB soundcard. So 2 audio shields could save money compared to one 4 channel audio interface.
It would be more elegant to have a solution with a direct bluetooth output without the additional analog path. But I am not aware of an easy solution and it would make it necessary to handle the pairing somehow.

Have you looked into USB bluetooth dongles? Would it be possible to use two of them from the laptop?
 
Thanks for your replay. Sorry I should have explained better.
I need two separate stereo outputs: one for the headphones and one for the speaker. I want to be able to use my bluetooth stereo speaker, but have the option to connect to other speakers as well (as an alternative to the bluetooth speaker) if I want to.
My midi mixer is just a midi controller to operate the various traktor controls.
Traktor manual states clearly it cannot use two separate audio interface so at present if I connect my bluetooth speaker, I can only use it either for cue listening monitoring or for master out, which is no good. (so for example I cannot send the audio to the speaker via bluetooth and use the laptop headphone output, as that will not work.
In theory I woudl not need inputs, for this particular usage (Not recording or using microphones). So if that helps I can just build an audio interface with two steroe outputs (this means 4 mono outputs of course). I have never build any bluetooth device so I don't know that side of the project requires or how it works. Is it possible to simple have a way of selecting where I want the audio to go to the jacks or via bluetooth?
 
I am not aware of a simple way to build a 4 channel output USB to bluetooth sound interface. I don't see that a Teensy is really making things easier here.
As I was trying to say:
- You would have to find a solution to make the Teensy a 4 channel USB audio interface
- connecting bluetooth devices to the analog outputs of two audio shields does not have an advantage over using a commercial sound interface
- I don't know if there is a solution to directly (i.e. somehow digitally) build a bluetooth output for a microcontroller

Plus: making the analog part of the audio shields reliable and without any risk of noise when connected to USB can also become tricky

So from what I know it seems to be better to use a 4 channel sound interface and put bluetooth transmitters on the analog outputs.

But no guarentee that other solutions are out there.
 
@Fluxia,
There is a lot of bluetooth audio transmitters you can find on aliexpress,from the very cheap to more elabotated,the same for receivers,
but there is a maybe a latency in these bluetooth stuffs,you can also use transmitters like those used with guitars and no latency (but mono?),
Also i don't know if beringhers mixers tables have latency in their bluetooth output.
With teensy you can use a patchcord with a toggle button (physical or TFT touch button) to dispatch your signal on the output you want.
 
Thank you all. After trying using Bluetooth speaker with my current gear I came to realise that the latency is more than I expected, so I will probably just do without the Bluetooth output. At this point I may probably consider getting just a very cheap audio interface with headphone and a digital output( which I can use to connect my speakers) and see how it goes. Having looked into teensy audio has given me ideas for the future though... Like building a DIY synth. That will probably be my next project. Thanks again for the advices.
 
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