Note: I originally posted this on 25ms.org, a blog that started my journey into the world of audio and JackTrip. I’m reposting it here in case it may be useful to others.
In my previous post, I tested the latency of the HiFiBerry DAC+ ADC Pro with great results. Today, I tested their less expensive model ($50 versus $65): the HiFiBerry DAC+ ADC. I used jack_delay as described in this post with Raspbian (kernel 4.19.118-v7l+).
Here are the device loopback test results, along with the previous Pro results for comparison:
| Device | Hz | FPP | Latency |
|---|---|---|---|
| HiFiBerry DAC+ ADC | 48k | 128 | 30.862 frames (0.64ms) |
| HiFiBerry DAC+ ADC | 48k | 256 | 30.865 frames (0.64ms) |
| HiFiBerry DAC+ ADC | 96k | 128 | 33.154 frames (0.69ms) |
| HiFiBerry DAC+ ADC | 96k | 256 | 32.081 frames (0.69ms) |
| HiFiBerry DAC+ ADC Pro | 48k | 128 | 51.100 frames (1.0ms) |
| HiFiBerry DAC+ ADC Pro | 48k | 256 | 50.416 frames (1.0ms) |
| HiFiBerry DAC+ ADC Pro | 96k | 128 | 50.393 frames (0.5ms) |
| HiFiBerry DAC+ ADC Pro | 96k | 256 | 50.459 frames (0.5ms) |
Device latency using local loopback, excluding buffer overheads (jack_delay -E)
And here are the full round-trip loopback results over the Internet:
| Device | Hz | FPP | Latency |
|---|---|---|---|
| HiFiBerry DAC+ ADC | 48k | 128 | 1823-2463 (-3ms) |
| HiFiBerry DAC+ ADC | 48k | 256 | 3359-4127 (+5ms) |
| HiFiBerry DAC+ ADC | 96k | 128 | 2336-2976 (+2ms) |
| HiFiBerry DAC+ ADC | 96k | 256 | 3616-4896 (+1ms) |
Round-trip loopback, including buffer overheads
I was very surprised to measure approximately 40% lower device latency for the the less expensive model! Like the Pro model, it still sounded great and produced nearly identical Audacity waveforms from a round-trip network test.
Unlike the Pro model, you have to swap a jumper on the board to enable the microphone boost, and it appears to be all or nothing. The Pro allows you enable and control the level of boost using alsamixer on a 0-100 scale, no jumpers required.