How to wire the balanced breakouts

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flatmax
Posts: 603
Joined: Sat Jul 23, 2016 11:39 pm

How to wire the balanced breakouts

Post by flatmax » Tue Jul 25, 2017 9:55 am

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 :
octo.balanced.connectionDiagram.forum.jpg
Audio Injector Octo balanced breakouts connection diagram
octo.balanced.connectionDiagram.forum.jpg (221.91 KiB) Viewed 1733 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
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flatmax
Posts: 603
Joined: Sat Jul 23, 2016 11:39 pm

Re: How to wire the balanced breakouts

Post by flatmax » Tue Jul 25, 2017 10:08 am

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.
octo.balanced.connectionDiagram.fieldRecording.forum.jpg
Audio Injector octo balanced field recording connection diagram.
octo.balanced.connectionDiagram.fieldRecording.forum.jpg (201.58 KiB) Viewed 1731 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
Checkout the latest kickstarter campaign - the Ultra !
https://goo.gl/8HdqDi
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

waldo
Posts: 1
Joined: Sat Sep 23, 2017 1:11 pm

Re: How to wire the balanced breakouts

Post by waldo » Sat Sep 23, 2017 1:31 pm

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
Posts: 603
Joined: Sat Jul 23, 2016 11:39 pm

Re: How to wire the balanced breakouts

Post by flatmax » Thu Sep 28, 2017 3:19 pm

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
Checkout the latest kickstarter campaign - the Ultra !
https://goo.gl/8HdqDi
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

MedicationTime
Posts: 14
Joined: Mon Oct 02, 2017 9:57 pm

Re: How to wire the balanced breakouts

Post by MedicationTime » Mon Oct 02, 2017 9:59 pm

Hi,

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

Thanks !

flatmax
Posts: 603
Joined: Sat Jul 23, 2016 11:39 pm

Re: How to wire the balanced breakouts

Post by flatmax » Wed Oct 04, 2017 7:07 am

I think it pulls around 0.3 amps.

Matt
Checkout the latest kickstarter campaign - the Ultra !
https://goo.gl/8HdqDi
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

Ivan
Posts: 11
Joined: Thu Jan 11, 2018 10:33 pm

Re: How to wire the balanced breakouts

Post by Ivan » Sun Jan 14, 2018 12:42 pm

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

flatmax
Posts: 603
Joined: Sat Jul 23, 2016 11:39 pm

Re: How to wire the balanced breakouts

Post by flatmax » Tue Jan 23, 2018 5:21 am

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

Matt
Checkout the latest kickstarter campaign - the Ultra !
https://goo.gl/8HdqDi
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

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