Topic: Firmware Updates ADI-2 Pro 180 / 88 and DAC 20 / 22

ADI-2 Pro / AE / FS. For ADI-2 DAC see second post.

This firmware update 180 for all ADI-2 Pro became urgent due to a bug introduced in the last FPGA version 177:

- Bug fixed that caused wrong samples on the analog recording signal's left channel at sample rates 352.8 kHz and higher

A fellow forum user pointed out that AutoDark mode with older Pro units easily causes the loss of the current power state when switching the unit into Standby. To prevent this we added visual feedback when to release the Standby button - the display now comes back to life (dimmed) for half a second as soon as the unit starts to shut down.

We were already working on some other things that now also go public in DSP version 88:

- Level meters of unused Phones 3/4 can be wrong

- Auto Ref level takes wrong channel's information from Dual EQ mode to calculate the available overhead

While these two issues were most probably never noticed by anyone, changes in SETUP are long overdue:

- New menu structure in SETUP for easier navigation and operation with new subpages Display and Phones

The menus found under SETUP - Options were a bit overcrowded and cluttered, thus not easy to navigate. For example Hardware / Diagnosis had 16 entries, Device Mode 10. Finding the correct entry not only requires a lot of scrolling, users often searched for an expected entry in the wrong subpage. Improving the structure turned out to be quite easy.

Step 1: Move all entries relating to display control into its own menu page called Display (Entries: Display Mode, Meter Color, AutoDark Mode, LCD Brightness, LCD Tint Control)

Step 2: Move all entries relating to Phones control into its own menu page called Phones (Entries: Dual Phones, Bal Phones Mode, Phones <=> Line, Mute v. TRS 1/2, Mute v. TRS 3/4)

Step 3: Move the option Dig. Out Source from Hardware / Diagnosis to Device Mode

Result: SETUP - Options now has 5 subpages, which make it more easy to find relevant settings and to remember where they are. Also some settings hidden at a lower position in the menu are now on top, quicker to find. Hardware/Diagnosis is down to 10 entries (from 16), Device Mode down to 6 (from 10), which makes vertical scrolling through all entries more quick.

These changes are fully compatible to earlier stored user setups.

The manuals German/English have been updated to version 2.2 with the new menu structure of SETUP, and are available here:



And there is one more:

- Added 6 dB headroom to the SRC to avoid intersample peak overloads

While the Sample Rate Converter is not an often used feature we still want it to operate as good as possible. I already confessed here: https://www.forum.rme-audio.de/viewtopic.php?id=26873, post 6, that we are aware that the SRC causes higher distortion when processing levels above 0 dBFS, the so called intersample peaks (all SRC chips that we are aware of do that). In firmware 180 we now gave the SRC 6 dB headroom to address this issue.

For the analog outputs, the SRC's output goes into the ADI's volume control with 24 dB headroom. A +3 dBFS input signal will now be properly sample rate converted and stays +3 dBFS. Consequently the level meters show 0 dBFS already at a volume setting of -3 dB, and at volume -2.5 dB they show Over. In other words: thanks to the internal headroom all one has to do is dial down the output volume until the level meters don't show Over, and one totally avoids the SRC intersample peak distortion. Easy and intuitive.

The interesting part here is that properly clipping the sample rate converted signal the same broadband distortion as when overloading the SRC will show up. Which happens at the digital outputs AES/SPDIF/ADAT and with USB recording the SRC signal. In normal operation there is no attenuation available in these signal paths to prevent clipping. Please note that the global level meter screen shows the effect on the output meters, red Over will be signalled.

Solution for the digital outputs AES/SPDIF/ADAT: The option 'Digital Out Source - Main Out' puts the volume control (all DSP) into the digital output path. Reducing the volume a bit (one to three dB) will keep the digital output meters from showing intersample clipping, because then there is no such overload anymore.

Solution for recording the SRC signal via USB: SETUP - Options - Device Mode. Basic Mode AD/DA, CC-Mode Multi-channel, Dig. Out Source Main Out. Then I/O - Main Output 1/2 - Settings. AD/DA Source - select the correct SRC input signal, SPDIF or AES. Then perform a loopback cabling on the other digital I/O, and set this loopback input as record input source in the recording software. The USB record signal can now be lowered by the ADI's volume knob a bit to stay clean.

In both cases DIGICheck's OVS (oversample) level meters will verify the correct VOL setting.

Sorry for the long explanation, now here are the firmware downloads:



Matthias Carstens


Re: Firmware Updates ADI-2 Pro 180 / 88 and DAC 20 / 22

The changes in DSP version 22 for the DAC are far less than for the Pro. Obviously there is no analog record bug, the other two issues were never in there, and the Standby button won't fail in AutoDark mode. Even the changes in the menu structure do not apply because most of the entries do not exist in the DAC at all.

Still for consistent operation we found it useful to give the DAC its own menu page Display:

- Added menu page Display with all entries relating to display control (Entries: Display Mode, Meter Color, AutoDark Mode, LCD Brightness, LCD Tint Contr)

Doing this causes Hardware/Diagnosis to have the Remap Key options as first entries, a small but useful improvement.

We also changed the lowest Low Vol Ref value of Loudness from -80 to -90 dB, as it was stated in the manual for a long time already.

The manuals German/English have been updated  to version 1.4 with the new menu structure of SETUP, and are available here:



Firmware download:



Matthias Carstens