VAlinks USB audio interface2018-01-02
Last year, I purchased a USB audio interface made by VAlinks. I can't find much about VAlinks, but they seem to be a Chinese outfit that sells audio and video devices and connectors online. The reviews on the Amazon.com version were evenly split between it working well and being useless, but I figured it was cheap enough that I'd give it a try anyway.
The device itself is very simple: One end is USB and the other end is 1/4" mono TS, with 3 m of cable connecting them. Plug one end into your computer, the other into your instrument, and you're set.
The USB end of the cable comes with a LED which is on when the device is plugged in and blinks when it's recording: This comes in handy when you're setting up and not certain which device you're recording from. The connector enclosure is a little bulky, so you might not have enough space to plug it in.
Surprisingly, the enclosure pops open with no tools and minimal effort: I was expecting to find clips, but it's held together with just a little friction. On one hand, I wish more devices were this easy to open! On the other, I'm a bit worried this will come loose and start falling open on its own.
Inside, there's a circuit board with a single IC: The chip is a C-Media HS-100B. It claims to be a "highly integrated single chip USB audio solution" with both a 16-bit ADC (useful here) and two DACs (for stereo output; not useful here).
On the other side of the board, we see the LED and connections: Interestingly, there's space for another chip on the board; I believe it's for the optional EEPROM chip that the HS-100B supports (the datasheet says it should be a 93C46, which comes in 8-pin SOIC).
The audio end of the cable has the look and feel of a low-end guitar cable:
Inside, though, I don't know what is going on: I'm hoping that the brown stuff is burnt flux, but there are also small white crystals of some sort. I think if this connector ever gives out, rather than desoldering it, I'll chop off the entire end of the cable.
At 3 m, the cable is a good length when near the computer. If necessary, it's trivial to extend it with a regular cable and any pedal.
It reports itself to the host as "C-Media Electronics Inc. USB Audio Device" with ID (vendor:product)
That makes sense, because there's no EEPROM chip present to customize these values.
It shows up as an output device as well as an input device. According to the datasheet, the HS-100B has an output-only mode and a bidirectional mode, but no input-only mode. (It's clearly not the right chip for the job here.) The output device can be ignored.
Since it appears to use the standard USB Audio Device Class, it works out of the box on Linux and macOS. It runs just fine on USB 3 ports and even through a USB 3 hub.
When recording, there is no audible noise. No hum, no hiss, no clicks. The amplitude of the background noise is many orders of magnitude less than that of the signal.
However, there is an issue with mechanical noises from the instrument being amplified too much. When I'm playing through my amp and I change my guitar's pickups and volume, I can hear very faint clicks and scratching, and I would expect to hear the same when playing through this interface. Instead, these sounds are significantly louder:
The problem is independent of computer and operating system.
It doesn't happen on my bass, since its pots are much newer:
This interface seems to have very little latency, which makes it possible to listen to yourself through the computer in real time as you play. It's definitely well under 100 ms, but I suspect that it's under 20 ms. To put that in context, 20 ms is how long it takes sound to travel about 7 m (22 ft).
In practice, the total latency will depend on many factors, including the operating system, drivers, and software. In the worst case (Audacity on macOS on a MacBook Pro), I was getting close to 400 ms, which is unusable for monitoring. In the best case (Audacity on Linux on a Samsung laptop), it was fast enough that I wasn't able to measure it, and I definitely couldn't hear it.
The low end comes through beautifully. Here's a bass with active pickups, played with fingers:
And with a pick:
Here's a fretless bass with passive pickups, played with fingers:
Sadly, I don't think clean guitar comes out well. My guitar doesn't have the brightest tone to start with, but I think this interface sucks away more tone, leaving behind a fairly dull sound:
There's supposed to be a "MIC High Pass Filter" (on by default; can be disabled in EEPROM), but it doesn't appear to be enough. Part of the problem might be that the filtering in the HS-100B is designed for voice. Or perhaps there's a capacitor to ground somewhere that acts as a low-pass filter, dumping all the treble.
With distortion (Boss DS-1), the lack of tone isn't as obvious to my ears:
I don't think it's just a problem with my guitar, either. Recording a digital piano, the sound is not nearly as rich as when playing through headphones directly:
The construction is better than what you'd find at a dollar store, but it still feels like a toy. I expect it'll last for many years with light use.
It uses common standards, so there are no issues with compatibility or drivers.
The audio quality (in terms of noise) and latency are excellent, though there are issues with amplified scratching and a lack of tone. If you're looking to record clean, bright tunes that sound like they came from a studio, look elsewhere. If you just want to experiment with recording your ideas on a tight budget, this ought to do the trick.
- I can't find a datasheet for the C-Media HS-100B, so I'm extrapolating from v1.1 of the HS-100 datasheet.