Re: [LAU] Affordable well-working USB interface with low latency at 48kHz?

David Kastrup <dak(a)gnu.org> writes: "Behringer U-Phoria" Back to my prejudices: 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. So even in the latency department, I am not really impressed though given the tests I've seen, this does not seem too uncommon for USB cards. Though there are plenty by now that are at least USB2.0 and can consequently, for example, do 96kHz at full-duplex (full-duplex audio, the USB is still half-duplex). It's most definitely not what I'd use for recording (and with a single mic input, it's not overly suited for that either). For jamming, it might fit the bill if you need a phantom power input. Not much justification for it beyond that I'd say over basically anything cheap with a line input to be had these days. I think it might be that model but I haven't asked back yet. -- David Kastrup