1 Topic by soundnerdie (edited by soundnerdie 2024-01-18 18:06:36)

  • Registered: 2023-11-27
  • Posts: 3

Topic: ADI-2/4 Pro SE as hardware I/O for measurements

Hi,

I wish to use the ADI-2/4 as an audio analyzer. I have read page 84 of the manual and note the following remarks.

Tips for optimal measurement results
Improve the signal-to-noise ratio (and thus THD+N) at the analog input by mono operation
To do this, simultaneously place the source on both inputs using a split cable and activate M/S processing in the analog input. The left channel now has an SNR of 124 dB (AES17) instead of 121 dB at unchanged level.

Improve signal-to-noise ratio (and thus THD+N) at the analog output by mono operation
To do this, use a split cable to connect both outputs, which must output the same signal, to one cable. This 'short circuit' uses internal resistors of the ADI to improve the SNR by 2.5 dB.

Pardon my ignorance but I hope to know:

What is the best wiring approach in a loopback setting (i.e., ADI-2/4 analog outputs -> ADI-2/4 analog inputs)?
What is the best wiring approach in a standalone setting (i.e., Other DAC analog outputs -> ADI-2/4/ analog inputs)?

Your help is much appreciated. Thanks in advance.

2 Reply by KaiS (edited by KaiS 2024-01-18 21:08:17)

  • KaiS
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  • Registered: 2020-02-05
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Re: ADI-2/4 Pro SE as hardware I/O for measurements

You already have everything necessary:

Measurement ADI-2 loopback:
ADI-2 L+R Out -> Y to mono XLRm cable -> -> mono XLRf cable to Y-split -> ADI-2 L+R input.

Measurement of an analog I/O DUT (Device Under Test):
ADI-2 L+R Out -> Y to mono cable -> DUT -> mono cable to Y-split -> ADI-2 L+R input.

Measurement of a DAC:
DAC running the test signal, e.g. sine wave -> mono cable to Y-split -> ADI-2 L+R input.


For each DUT of course you need fitting cables and adapters, in order of preference: XLR (balanced and single ended), TRS (balanced and single ended), RCA.

For single ended operation do NOT short ADI-2‘s XLR OUTPUT‘s pin 3 to ground, leave it open.

For single ended operation do short ADI-2‘s XLR INPUT‘s pin 3 to ground.

On ADI-2 best only use the XLR outs, the TRS’s out’s reference level doesn‘t use the highest step.

KaiS's Website

  • Registered: 2023-11-27
  • Posts: 3

Re: ADI-2/4 Pro SE as hardware I/O for measurements

Thanks, Kai.

For single ended operation do NOT short ADI-2‘s XLR OUTPUT‘s pin 3 to ground, leave it open.
For single ended operation do short ADI-2‘s XLR INPUT‘s pin 3 to ground.


I don't quite understand this. They both mentioned single ended operation.

Thanks.

  • KaiS
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  • Registered: 2020-02-05
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Re: ADI-2/4 Pro SE as hardware I/O for measurements

soundnerdie wrote:

For single ended operation do NOT short ADI-2‘s XLR OUTPUT‘s pin 3 to ground, leave it open.
For single ended operation do short ADI-2‘s XLR INPUT‘s pin 3 to ground.

I don't quite understand this. They both mentioned single ended operation.

Read again.

ADI-2‘s XLR OUTPUT needs different handling than ADI-2‘s XLR INPUT, when operated single ended.

KaiS's Website

  • Registered: 2023-11-27
  • Posts: 3

Re: ADI-2/4 Pro SE as hardware I/O for measurements

Now I see! Thanks smile