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[InflatableMouse]

I own a Tascam UH-7000 AD/DA USB device. When I run Wavespectra using ASIO and WASAPI, I get these spikes:

click for full size

They appear on the Left channel, the right channel only gets them when I increase recording volume.

I tried a lot of things:
- unplugged all the cables except USB of course
- changed wall outlet to a different power group
- turned off all other devices in its vicinity
- changed USB cable
- swapped USB ports
- downgraded/upgraded the firmware
- tried different driver versions
- tested with different latency settings
- tested when device is cold and just switched on (ie, not heat or time related)
- used a different PC for testing

I realize its all academic with the spikes well below hearing treshold and higher than what we can actually hear but it still annoys me that a device of this class would get it.

Last but not least, a friend of mine owns one too and he's seeing the exact same thing.

PS. I filed a support case with Tascam as well today.

If anyone has any suggestions please share. I'm out of ideas. Maybe my friend comes back with a smart idea (he's way more knowledgable than me anyway) but there are a lot of smart and knowledgable folks here too.

Thanks!

[mwillems]

How are you capturing the output?  Are you using the TASCAM's input or something else? Is the input you're using to record a stereo input or a mono input?

The fact that it appears in the right channel when you increase the recording volume suggests you may either be using a mono input, or you may be seeing some kind of electrical feedback from coupling the outputs to the inputs (or both).  If you have another device that has inputs sensitive enough you might want to try measuring that way to rule that out.

And, FWIW I wish I got loopback measurements that good     -140dBFS across most of the band with occasional spikes to -120dBFS is miraculously good (I do see the spike/triangle up to -100dBFS at the lowest octaves, but it's below -120 almost instantly, and that's very, very good).  

[InflatableMouse]

Yes, Tascam's input, device itself is connected via USB. Wether the cables are connected to the input or not doesn't make a difference. The Tascam is in multichannel mode, which for me means stereo . Switching to stereo mix (mono) doesn't matter for the measurements. The only thing that matters somewhat is the latency setting in the devices' control panel. Set to the lowest, the spikes go up. But one or two steps higher its all the same as in the screenshot.

I agree the device measures very good in general and I'm very happy with it. Recordings really do sound better than with the consumer devices I owned.