Internal noise of HDD-based recorders: let's compare!

[Toki]

I have also initiated the topic here: http://taperssection.com/index.php/topic,92137.0.html

I have been doing a record in local philarmony yesterday, sitting very far from performers, and was trying to estimate the sensitivity of my recording system. My equipment was RODE Stereo Videomic attached directly to the line input of rockboxed Cowon iAudio X5 player. Recording was done in pcm wav 44k. I had to use maximum gain (+12db) on player since the sound was silent and no preamp was used. Listening to the results I found that the biggest problem of the record was HDD spinning noise. I tried to deattach the mic, but the noise remained in the records - thus it is not a noise picked up by the mic from player "from the air" but internal noise. It was possible to make this sound almost unnoticeable only when I lowered gain to about -7db.

So I have few questions:

1) is it a normal having such noise for all players of this type?
2) if it is a common problem of all HDD players? And if it is,
3) can we make a comparison test of a noise level of hdd-based recorders with gain set to a high level and wit/without mic?

Here are my samples:

HDD noise with +12db gain, amplified in post:
http://www.mediafire.com/?5fxb2xuxdb3

Original file of the same sample:
http://www.mediafire.com/?2jcm9wbt4yx

A sample of very silent vocal music with HDD noise:
http://www.mediafire.com/?a6c5yzhmd9x

(all samples are about 3mb wav files)

And the noise specter viewed in adobe audition:


P.S. it is worth to note that it was at least once that there was a warning message over timeline in recording screen Warning: 00000002. It didnt affect the output files but since it is not normal if you see this message too leave info here. thanks.

[saratoga]

If you really want to measure, you should use RMAA.  Play back the test signal over am ok soundcard and record it with Rockbox.  Then load it back into RMAA and it'll give you the SNR figures, THD, stereo crosstalk, etc.   Its really handy for this sort of work.

[dreamlayers]

Some devices such as my Archos V2 Recorder can record from a digital source and in such cases there shouldn't be any electrical noise from the recorder.  It seems like A/D converters are expensive however.  It's probably best to just get a preamp so you can decrease gain on the device.

Don't assume that flash based devices don't have electrical noise.  For example I've read that the Sansa e200 series have electrical noise on the output when reading flash.  

[petur]

Don't assume that flash based devices don't have electrical noise.  For example I've read that the Sansa e200 series have electrical noise on the output when reading flash.  

I thought the interference came from the LCD. But I could be wrong, no sansa here to check....

[Llorean]

I believe buffering, LCD, and the ring-light all can cause audible noise during playback, actually. Honestly, the Sansa's not my favorite device for sound quality, though under most circumstances I don't notice it.

[kensuguro]

I'm an audio guy, not an electronics guy..  i use sansa e260, and I get noise from LCD when I record.  It goes way after the LCD times out.  But rule of thumb is, where there's electric current, there's going to be noise unless it's been shielded right.  In most cases with these devices, they're not built for high quality recording so I'm guessing it's a hardware limitation.

I think the sansa's great for recording live gigs tho.. I take it home, and EQ it a but to try to put things back in prespective, and it turns out not so bad compared to the usual "got it off my video" recordings.