Because I am Here

I recently purchased two sets of podcasting gear to record podcasts with someone in another state. The gear included two TASCAM US-144 mkII interfaces, two Audio-Technica AT 2020 condenser microphones, two mic cables, two stands, two pop filters, two sets of headphones, etc. As I recorded I noticed an inconsistent whine in the audio. Sometimes the wine was little more than a vinyl-record-like scratch, other times it was a scream, and still others it disappeared altogether.

To track down the source, I started by changing out the AC power for battery power, switching USB cords, switching mic cords, switching microphones, switching interfaces, turning on and off the wireless network, unplugging my wireless router, changing rooms, and even moving to a location several miles away. None of these things had any consistent effect on the whine. After a lot of trial and error, I have narrowed the problem down to two three variables: Temperature, Phantom Power and the MIC/LINE-GUITAR select switch.

The whine appears with the phantom power on, while the interface is cold (ie, less than about 65 degrees Fahrenheit). It gets worse when the MIC/LINE-GUITAR select switch is set to “Guitar.” Setting the MIC/LINE-GUITAR select switch to “Guitar” makes it act as an unbalanced input jack, which probably explains the noise. But turning on the phantom power while the interface is cold produces a lot of noise.

The solution: Sit on the interface to warm it up. My home “studio” is in a very cold room with two exterior walls, and it’s the middle of winter. So in order to warm up the interface—no joke—I actually put it under my thigh for a good 10-15 minutes. I didn’t read that helpful work-around in the manual. I thought about using an electric blanket, but I was afraid that might cause some induction damage.

The Test

I conducted a test to demonstrate the whine, which I have included here. For the test I had the following setup: I plugged an Audio-Technica AT 2020 condenser mic into the MIC IN L XLR balanced jack. I also plugged a crappy old dynamic mic into the LINE IN R/GUITAR IN jack TRS 1/4″ jack. For the “Cold” test, I left the interface in a box in my car for 30 minutes, where the outside temperature is around 25° Fahrenheit. For the “Warm” test, I basically sat on the interface for about 15 minutes until the interface housing was noticeably warmer than room temperature.

I then recorded a systematic test of the phantom power, left and right input levels, and the MIC/LINE-GUITAR select switch in 10-second intervals. I included the results in a table below, with each numbered setting corresponding to a period of time on the non-normalized .mp3 file. You can skip around to compare the different settings if you’d like. Please ignore the ambient noise of the HVAC system, as well as the lousy line quality for my crappy dynamic mic.

INTERFACE TEMPERATURE: COLD (~30°- ~65° Fahrenheit)
Setting	Time on Tape	Phantom Power	INPUT L Levels (AT 2020)	INPUT R Levels (Crappy Dynamic)	LINE/MIC- GUITAR Select Switch	Whine
1	0:00-0:10	OFF	Line (Low)	Line (Low)	Line/Mic	None
2	0:10-0:20			Mic (High)	Line/Mic	None
3	0:20-0:30			Line	Guitar	None
4	0:30-0:40			Mic	Guitar	None
5	0:40-0:50		Mic (High)	Line	Line/Mic	Scratch
6	0:50-1:00			Mic	Line/Mic	Scratch
7	1:00-1:10			Line	Guitar	Scratch
8	1:10-1:20			Mic	Guitar	Scratch
9	1:20-1:30	ON	Line	Line	Line/Mic	Whine-Low
10	1:30-1:40			Mic	Line/Mic	Whine-Med
11	1:40-1:50			Line	Guitar	Whine-Med
12	1:50-2:00			Mic	Guitar	Whine-Scream
13	2:00-2:10		Mic	Line	Line/Mic	Whine-Loud
14	2:10-2:20			Mic	Line/Mic	Whine-Loud
15	2:20-2:30			Line	Guitar	Whine-Loud
16	2:30-2:40			Mic	Guitar	Whine-Scream

INTERFACE TEMPERATURE: WARM (~75°+ Fahrenheit)
Setting	Time on Tape	Phantom Power	INPUT L Levels (AT 2020)	INPUT R Levels (Crappy Dynamic)	LINE/MIC- GUITAR Select Switch	Whine
1	2:40-2:50	OFF	Line (Low)	Line (Low)	Line/Mic	None
2	2:50-3:00			Mic (High)	Line/Mic	None
3	3:00-3:10			Line	Guitar	None
4	3:10-3:20			Mic	Guitar	Scratch
5	3:20-3:30		Mic (High)	Line	Line/Mic	Scratch
6	3:30-3:40			Mic	Line/Mic	Scratch
7	3:40-3:50			Line	Guitar	Scratch
8	3:50-4:00			Mic	Guitar	Scratch
9	4:00-4:10	ON	Line	Line	Line/Mic	None
10	4:10-4:20			Mic	Line/Mic	None
11	4:20-4:30			Line	Guitar	None
12	4:30-4:40			Mic	Guitar	Whine-Loud
13	4:40-4:50		Mic	Line	Line/Mic	None
14	4:50-5:00			Mic	Line/Mic	None
15	5:00-5:10			Line	Guitar	None
16	5:10-5:20			Mic	Guitar	Whine-Loud

My home studio is in the basement near an outside wall, so it’s usually around 65°. Every morning the whine reappears until I physically warm the unit to around 75°+.

At lower temps, the phantom power whines and bleeds over into the 1/4″ inputs, which surprises me because most electronics are happier when they’re cold. I’d chalk it up to a defective unit, except that I purchased two 144 mkII’s, and both units display the same behavior. Regardless, I’m not looking forward to the hassle of returning or exchanging the interface. It’s going to put me back several weeks.

I wonder if anyone else has experienced these same problems. The helpful guys at Sweetwater didn’t seem to have bumped into the problem before.

[Update Jan 14, 2010]

I have decided to return the mkII’s to Sweetwater in favor of another brand, perhaps an M-Audio. I haven’t decided. At first I was content to swap them out for non-defective mkIIs, but apparently TASCAM has temporarily stopped shipping the US-144 mkII. More precisely, they are taking orders without providing a firm ETA. This is apparently quite unusual, and in the estimation of the guy I talked to it likely indicates that they are doing some re-tooling.

I decided that I’m probably better off not being the guinea pig for the “fixed” version (if, in fact they are re-tooling). And even if they’re not re-tooling, I don’t want to wait indefinitely for TASCAM to fill the order.

I am so glad that I purchased from Sweetwater instead of Guitar Center. Sweetwater has much better support. Let me correct that: Sweetwater offers any type of support.

[Update Jan 25, 2010]

I decided to go with a Lexicon Omega instead. So far (in some preliminary recordings) I haven’t had any noise problems, thought the levels are significantly lower than the Tascam 144 mkII. I’ll just have to do more post-normalization. I hope the noise levels stay tolerable.