A Good Headphone Amp/Mic Input, but Not for the Studio
By Paul
Rated 3 out of 5
Date: 2022-06-06
I bought this with a specific use case in mind - I wanted to integrate remote guests into my podcast setup using an iPhone and Apple's camera adapter. In other words, I wanted to use this as a separate audio interface to send a mono mix minus from my mixer to the guest on a Zoom call, and get the guest's audio into my recorder. It turns out it will work for this purpose, but I can't really recommend it, as I'll explain below.
First off: this thing comes with no real manual to speak of and there is not real manual available on the web site, so I had to experiment to figure out how some things work. Also, you will want to update the firmware using the Rode Central app on Windows or MacOS before trying to use it with an iOS device.
It makes a really good DAC/headphone amp. The DAC is very clean and crisp and the built-in headphone amp is very powerful and should drive anything you have around. So if you just want to use it to listen to your music collection I highly recommend it for that. I'm actually going to use one for that purpose.
It also has a very good mic preamp in it for the one input, with enough gain to use even with dynamic mics like the Heil PR-40. So if you want to use it to get one microphone into your computer for recording, I recommend it for that, too. You can turn on phantom power by pushing the knob in. I didn't try it with a condenser mic but given the general quality I would assume that would also work well.
The TRS in on the combo jack input also works fine with an electric guitar and its sounds quite clean, with plenty of gain. I did not try it with something like a drum machine or synthesizer output.
If you want to monitor the input directly, rather than hearing what your connected computer or phone is sending, you push in the right knob and turn on direct monitoring. So far, so good.
You can use the mic/instrument input and turn on direct monitoring, and _also_ listen to the audio your computer or phone is playing. If you turn on the direct monitoring, you have a little mixer. So you can, for example, play guitar over a backing track to practice and it will sound very good through your headphones.
Things get strange when you want to use the rear pair of TRS outputs. This thing will drive _either_ the rear outputs or the headphone jack, but not both. If you plug in headphones, you'll get nothing out of the TRS outputs.
When you have TRS cables plugged into the rear outputs, the output level is controlled with the right knob on the front panel. This is a strange choice, because let's say you have the knob all the way up, and then plug in a pair of headphones, forgetting to turn the knob down. What happens? You'll blow your headphones up. Or your ears. So, that's a design choice I really disapprove of. I know there's not much space on this device, but a separate knob that is always dedicated to headphone volume would be a better design choice.
If you have cables plugged into the rear TRS outputs, and the direct monitoring engaged, you'll get your microphone or instrument input out the back, so you can record your live mic or instrument into your computer or phone. That's all well and good.
Now, for some strangeness. The rear outputs have very low gain when play the output from your computer or phone. So, let's say you wanted to play audio from your computer or phone directly into a set of powered speakers with balanced inputs. You're going to have to turn the speakers way up to get a normal volume level, adding noise. That's not good.
I compared two devices side by side, a phone driving the outputs of a Focusrite Clarett+ 2pre, and another phone driving this device, both playing test tones such as a pink noise and a sine wave at -20dB. Running this into an SSL SiX, it was obvious that even with the right knob all the way up, the output from the AI-1 is not at all full scale. I also tried it into a Sound Devices MixPre 6 II. To get the levels to match, I had to add about 12 or 13dB of gain on the inputs.
The situation on the input is much worse, though. If you want to use the combo jack with a TRS input, it's problematic. Sending the alt monitor mix output of the SSL SiX, with the mono switch engaged, using a TRS cable, into the AI-1, even with the left knob turned all the way down, the input gain was too high and my signal would severely clip the input, indicated by a red light (you get red, yellow, and green to give you a sense of how hot your input is). I had to turn down the monitor mix level down to about 3/4 to avoid the clipping.
Worse, even when the input via a TRS cable is low enough to avoid clipping, there is, as some other reviewers have noted, nasty digital noise on the input. If I record the input to my phone it is present on the playback, which means my remote Zoom guest will get this noise. Since Zoom is not known for its audio quality to begin with, I can probably live with this. Note that the digital noise isn't present on the AI-1 _outputs_, just the input, and only when using a TRS cable, not an XLR cable or TS instrument cable.
Thinking that maybe I had a bad unit, I wound up ordering a second one from the other company that sends you candy with music gear thrown in as a bonus. So I actually tested two units. Both needed the firmware update, but both behaved identically.
Oh, also, the front knobs on both units feel just a little bit loose. There's a bit of play in them. That's a minor annoyance but unexpected.
I'm hoping maybe a future firmware update might fix the output level. I'd be much happier if I could get full-scale output from the rear TRS sockets. I don't think they can fix the TRS input with a firmware update. I think that's a circuit design issue.
If they make a Mark II, I'd suggest:
- Adding a line/inst button on the front panel to change the characteristics of the TRS/TS input for instrument or line level - basically, turn off the high impedance that is desirable for something like an electric guitar and change the gain staging.
- Break out the headphone volume control/rear output volume control into separate knobs, with pass through behavior you can turn on, on _each_ of them.
Some of these features could be added in software, but at present there doesn't seem to be any way to control things like the rear output gain using software. The Rode Central app will only update the device firmware. But if there was a Windows, Mac, and Phone app that would control some of these parameters and they were persistent after power-cycling the device, that would be great, and I could live without some hardware knobs and buttons.
