The RME HDSPe MADI PCI Express card works with ALSA and Linux, but at the time of writing hdspconf doesn't recognize it. Many of the control values can be set using amixer and alsamixer.

Controls can be displayed using amixer:
amixer -c0 controls | less

and current control values:
amixer -c0 contents | less

where -c0 refers to the first sound card in the system (use -c1 for second card, -c2 for third, etc.).

To display a specific value, eg. System Clock Mode
amixer -c0 cget iface=MIXER,name="System Clock Mode"

Clock Source

The default clock source is internal. To set the card to slave to an external clock:
amixer -c0 cset iface=MIXER,name="System Clock Mode" 1

which sets the sample clock source to AutoSync (item 1 in the enumerated list). This presupposes that there is a valid clock source plugged in and the Error LED is green (and in the case of Word Clock input, the green Lock LED is lit).

IMPORTANT: At time of writing, ALSA doesn't detect the external clock frequency automatically at sample rates above 48kHz. The "Internal Clock" has to be set manually to the same frequency as the external clock to notify ALSA and jackd. External sync works correctly; the manual setting is just to notify the software. If you forget this jackd will fail to start.

Problem With SSL Alpha-Link at 96kHz Sample Rate

The HDSPe MADI works fine with the Solid State Logic Alpha-Link MADI AX and MADI SX at 44.1, 48 and 88.2 kHz in non-S/MUX mode, but it doesn't work at 96kHz. This is due to a bug in the Alpha-Link which causes it to incorrectly switch the output to 48kHz frames when running at 96kHz in non-SMUX mode. It needs to be set to SMUX mode in order to work at 96kHz.

To set the HDSPe MADI to run at 96kHz in SMUX mode:
amixer -c0 cset iface=MIXER,name="Internal Clock" 5
amixer -c0 cset iface=MIXER,name="MADI Speed Mode" 1
amixer -c0 cset iface=MIXER,name="Disable 96K frames" on

Note the upper-case 'K' in '96K' and lower-case 'f' in 'frames' in the third command. Also note that the internal clock needs to be set to the correct sample rate even if synchronised to an external clock.

Input Source

To change the MADI input from the default coaxial to optical:
amixer -c0 cset iface=MIXER,name="Input Select" 0

Note that this isn't necessary to get a valid clock signal from the optical MADI input, as AutoSync will detect it whether selected or not.

Other controls can be set using similar command syntax after looking at the information displayed by `amixer -c0 controls'. Some of these are read-only and depend on other writeable values being set; they are provided as indicators only.


Playback levels can be set from the text console using alsamixer. The default playback level is zero, so these need to be set to get any output. Capture levels can not be altered from unity gain, despite alsamixer showing movable faders when started with the capture option (they don't do anything). To start alsamixer:
alsamixer -c0

which starts it with playback level faders displayed. Values range linearly from 0 to 100, with 100 being +6dB and 50 being unity gain.

Alternatively, starting hdspmixer (with X running) will initialise the playback levels to unity gain.

Save Settings

To save the current settings:
/usr/sbin/alsactl -f asound.state store

This will store the current settings in the file asound.state. To restore these settings next time they are needed:
/usr/sbin/alsactl -f asound.state restore

Here are a couple of working asound.state files which have been tested on Debian 10 with 5.4 kernel. Both assume HDSPe MADI is the default device, with clock synchronised to MADI input: asound.state-hdspe-madi-48k asound.state-hdspe-madi-96k

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Last updated December 20 2020