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How to correctly wire balanced & unbalanced instruments to AP512c?
Old 9th February 2020
  #1
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How to correctly wire balanced & unbalanced instruments to AP512c?

Hi all,

I have recently decided to look at purchasing some outboard gear (notably a API 512c preamp) for the first time, and was wondering how to correctly wire my instruments to this.

I would be looking to record my Jomox Alpha Base (balanced outputs), DSI Tempest (unbalanced outputs) and maybe eurorack (unbalanced outputs) into the 512c.

Am I correct in thinking that the best way to do this would be:

Jomox Alpha Base (balanced outputs) - TRS to XLR cable into the mic input of the 512c.

DSI Tempest (unbalanced outputs) - TRS to XLR cable? into the mic input of the 512c?

Eurorack (unbalanced outputs) - Not sure about this one, I would gather some sort of DI box to convert to mic level, then into the mic input of the 512c?

Can anyone please help with the above / let me know whether I am thinking about this in the wrong way? I’m not entirely sure whether the Hi-z input on the API 512c would be of any benefit?

Cheers!
Old 9th February 2020
  #2
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What exactly are you hoping to accomplish by inserting the preamp into your signal chain? It's primary purpose is to amplify low level signals to be line-level (i.e. microphones), while not adding noise or coloration; for gear that already outputs a line level, that's not at all necessary.

At any rate, your synths would probably overload the microphone input even with the pad engaged. It would probably work best to connect them to the instrument input with the pad turned on, which gives a reasonable line level input range. It's not at all clear if this input is balanced or unbalanced; I suspect unbalanced, in which case TS cables are the way to go.

For the unbalanced outputs on the Tempest, you don't want to use TRS cables; depending on what output jacks they have and exactly how they're wired, you could end up with a connection that just doesn't work as the ring would not be connected to anything and so half the balanced connection would be floating.
Old 9th February 2020
  #3
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nosebleedaudio's Avatar
 

Whats pretty common is to use a passive DI box between KB & Mic pre input, NOT the same as using HiZ input on 512..
Old 9th February 2020
  #4
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Quote:
Originally Posted by DrewE View Post
What exactly are you hoping to accomplish by inserting the preamp into your signal chain? It's primary purpose is to amplify low level signals to be line-level (i.e. microphones), while not adding noise or coloration; for gear that already outputs a line level, that's not at all necessary.

At any rate, your synths would probably overload the microphone input even with the pad engaged. It would probably work best to connect them to the instrument input with the pad turned on, which gives a reasonable line level input range. It's not at all clear if this input is balanced or unbalanced; I suspect unbalanced, in which case TS cables are the way to go.

For the unbalanced outputs on the Tempest, you don't want to use TRS cables; depending on what output jacks they have and exactly how they're wired, you could end up with a connection that just doesn't work as the ring would not be connected to anything and so half the balanced connection would be floating.
Thanks for your reply. I am hoping to accomplish colouration of drum machines / eurorack drums. I don't intend to use it for anything else.

Quote:
Originally Posted by nosebleedaudio View Post
Whats pretty common is to use a passive DI box between KB & Mic pre input, NOT the same as using HiZ input on 512..
Thanks - do you think these instruments will still be too hot for the Hi-z input?
Old 11th February 2020
  #5
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Quote:
Originally Posted by Ruse View Post
Thanks for your reply. I am hoping to accomplish colouration of drum machines / eurorack drums. I don't intend to use it for anything else.
I honestly hope it works out for you. That said, adding a device that is clearly designed to have flat response (+0, -0.3 dB from 30 Hz to 20 kHz, per the specifications) and low distortion (less than 0.05% at nominal output levels) as a way of introducing coloration doesn't strike me as a very productive approach.
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