On Thu, Dec 17, 2020 at 03:08:54PM +0100, David Kastrup wrote:
just got an UMC22. Its codec is a Burr-Brown (TI)
PCM2902. Looking
up its specs, it's USB1.1 full speed and sports stuff like
• Stereo ADC
– Analog Performance at V BUS = 5 V
– THD+N = 0.01%
– SNR = 89 dB
– Dynamic Range = 89 dB
– Decimation Digital Filter
– Pass-Band Ripple = ±0.05 dB
– Stop-Band Attenuation = 65 dB
– Single-Ended Voltage Input
– Antialiasing Filter Included
– Digital LCF Included
"Not recommended for new designs" (currently the card is being sold
new everywhere), an USB1.1 (and USB is half-duplex, so this is
certainly responsible for part of the latency) 48kHz design with a
16-bit ADC specified for slightly above 14bit of precision.
And that's the naked codec, without being impacted by any circuitry
around it.
It's more compact for sure than my current solution at one ensemble
member (mic input into a Mackie Onyx 400F with dead digital circuitry,
out via the plugin jack into the mic input of a laptop).
For -p64 (without --sync) I get
464.320 frames 9.673 ms total roundtrip latency
extra loopback latency: 272 frames
use 136 for the backend arguments -I and -O
(the -O and -I values are independent of -pxx I think).
For comparison: with my Alesis iO|14 (Firewire, a lot more inputs and
outputs) I get 81 for the backend arguments regarding additional
loopback latency. With a Hammerfall DSP (PCMCIA card via expresscard
adapter, so routed through a PCI to PCIx converter) it's 31 if I
remember correctly.
Yes, this is a bit disappointing from the UMC22.
Thank you for taking the time to post the specs & test results, though!
I need to ask
the exact model of Behringer that my one orchestra
colleague got. That one's performance (regarding latency/dropouts)
did not really appear to improve upon my stone-age Tascam US-122L
I think it might be that model but I haven't asked back yet.
OK, will be interesting to know.
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