How to wire the balanced breakouts

[flatmax]

If you have purchased/received the balanced breakouts, then wiring them up is simple once you know, but seems like a jigsaw puzzle at first.

Here is a connection diagram :

Audio Injector Octo balanced breakouts connection diagram

octo.balanced.connectionDiagram.forum.jpg (221.91 KiB) Viewed 8653 times

Key thing is to make sure the preamp is plugged correctly into the Octo sound card. The mechanical holes should line up perfectly. The 8 outputs are on the left side, the 6 inputs are on the right side.

There is no phantom power provided on the input side (some condenser microphones require phantom power).

NOTE: you can wire up without the preamp if you want to do field recording with only the 5V supply, however you will have to be careful and reduce the gains of the ADCs and DACs from full scale to get linear recordings without clipping.

Matt

[flatmax]

For field recording, you can remove the preamp, however your dynamic range will be reduced.
In this case, the balanced breakouts can draw their power directly from the 5V output from the Pi's power supply. This means you only need to power the Pi and the balanced breakouts will be powered as well.

To use this setup, you will have to reduce your ADC and DAC gains from full scale to make sure you get a linear signal.

Audio Injector octo balanced field recording connection diagram.

octo.balanced.connectionDiagram.fieldRecording.forum.jpg (201.58 KiB) Viewed 8651 times

If you will be using microphones which require phantom power, you will need to power them yourself. Dynamic microphones typically don't require external phantom power.

Matt

[waldo]

Hey, new guy with question. I don't have a board in hand yet.

Can I assume that I could wire balanced i/o directly to the hat pins? Reason being that I want xlr and no preamp. So I would wire xlr jacks to a header to plug straight into the hat pins.

If so, can you point me to the pinout?

cheers,

waldo

[flatmax]

Hi there,

Yes you can do this.
Have a look at the pdf of the schematic here :
https://github.com/flatmax/AudioInjector.Octo.balanced

The pdf gives all of the pin inputs to the balanced header. You can work out the sound card pin headers from this.

Matt

[MedicationTime]

Hi,

there's no mention of max current for preamp's voltage supply. Anything in particular ?

Thanks !

[flatmax]

I think it pulls around 0.3 amps.

Matt

[Ivan]

Where can we buy the preamp board and the balanced breakout boards?

[flatmax]

We have run out of stock for the balanced boards. There is low demand so we will not manufacture any more.

Matt

[PRiZM]

We have run out of stock for the balanced boards. There is low demand so we will not manufacture any more.

Matt

If you are not manufacturing any of these board any longer could you tell me where I could get one made I really need Balanced breakouts and the preamp card for the Octo. Thanks in advance for any thing you can do..