Topic: preamp on 48kHz recorder records at 44.1... Help!

[Swampy]

I taped a show last night going warm mod UA-5 > iRiver H120. The pre was set to 48kHz but when I dumped the file to the computer, it was a 44.1 file. The file sounds great, but that doesn't seem right to me. Shouldn't it sound like its skipping the whole time if the pre was truly putting out 48kHz and it only recorded 44.1kHz? I thought it just syncs with whatever output the a/d is giving it, so does that mean that my UA-5 was giving it 44.1? Any help would be appreciated...

[DSatz]

swampy, there are various possibilities. One is that the recorder synched itself to the incoming bitstream and recorded all the samples as they came in (i.e. at 48 kHz) without skipping or burping--but then stored them in a file that it marked as being at 44.1 kHz, since that's the rate it was expecting.

A receiving circuit can lock onto an incoming signal simply by following its ups and downs, irrespective of whether or not it "knows" the nominal data rate of that signal. (Up is up; down is down; so who's counting?)

If that's what happened, then when you play that file back, it should play back nearly 10% slower (and lower in pitch) than the original sound. That's about one-and-a-half musical semitones--like the distance between, say, an F and a basically out of tune note sitting between E and E-flat. Does the recording sound OK except for the pitch and speed being slow to that degree? If so, various kinds of editing software (e.g. Sound Forge) can simply alter the WAV file header to indicate the correct (48 kHz) sampling rate, and then it should be fine.

Some equipment can accept a bitstream at one sampling rate and record it at a different rate; some equipment does a (possibly unnecessary) conversion even if the incoming bitstream is at the same nominal sampling rate as what you're going to store on disk. But I don't think that the iRiver does that.

--best regards

[Swampy]

Hmm, I checked with a guitar and it doesn't seems to be off by a semitone and a half, and the time looks right (it was a 2.5 hour show, so I'd probably notice a ten percent difference... I guess I should just spread it? Everything seems to be kosher?

[petur]

Rockbox or original firmware?

Rockbox should record it in whatever bitrate you give it, just make sure the signal is connected and stable before you start recording.

If it sounds ok, time is ok and says 44.1kHz, then that is what it is. Rockbox doesn't resample, no idea what the OF does...

[Swampy]

Ya, Rockbox. Not sure what build, I'm not home. But time and pitch are good, and the file was 44.1, but I'm sure the UA-5 was definitely on 48... Weird. Thanks for the opinions