Tascam DR40 noise like Blue Snowball

[whbjr]

Tascam DR40 recorder, running on batteries, using the built-in mics, picks up the same 1kHz noise that others have noted in the Blue Snowball mic:



This is definitely something I noticed after the fact - it's possible that the audio has been compressed, boosting the quiet-but-noisy part. I can guarantee that no computers were anywhere near... but hmm, I wonder if my smart phone was in my pocket? I need to go back and try again, recording under the same conditions. But in the audio file which this is analyzing, the 1kHz noise is definitely audible.

This is NOT an Audacity problem, and for that matter it's not a Windows problem, either, but here I am using Audacity on a Windows machine, so...

- Win

[kozikowski]

I can guarantee that no computers were anywhere near...

Oh, I wouldn't say that. This is a quote from the spec sheet.

USB 2.0 jack and cable for transferring recordings to computer

So all the USB command and control services are right there on the DR-40 motherboard. It's the USB Management signals that cause the Yeti Curse, formerly Frying Mosquitoes.

Over weeks we found that it wasn't the management signals getting into the super sensitive MicPre, by far the obvious "usual suspect," but the A/D converter. We had one poster whose audio/microphone system was dead, but the unit still managed to whine at us. The only thing left was the A/D. Nobody believes the signal is affected once the audio becomes ones and zeros. It has to happen when the show is still volts.

I'm going to climb into my Conspiracy Jacket and claim that "somebody" made a super cheap A/D converter at some unspecified time in the past and everybody dropped what they were doing as a hot rock and piled on the New Chip band wagon. I have several instances of one model of USB audio converter that splits that date. The ones made before that time don't whine. The ones made after that do.

Any minute now I'm going to pop them apart and see what's in there.

Koz

[whbjr]

I can guarantee that no computers were anywhere near...

Oh, I wouldn't say that.

Right - let me clarify: No other computers were near! (My point was, it wasn't a USB cable, or an external power supply.) Personally, I was suspecting the LCD display driver, because who else would operate as slowly as 1kHz?

I'm going to climb into my Conspiracy Jacket and claim that "somebody" made a super cheap A/D converter at some unspecified time in the past and everybody dropped what they were doing as a hot rock and piled on the New Chip band wagon.

I like this theory a lot - at some point in the "recent" past, A/D converters and Embedded CPUs and RAM dropped enough, causing hand-held recorders like this one (Tascam) became cheap enough to sell to customers like this one (me).

[kozikowski]

I was suspecting the LCD display driver, because who else would operate as slowly as 1kHz?

How about the service that's constantly polling the USB connection to check for activity?

Koz