Having to set recording level meter really low. Normal?

[7track]

Hi! I've just got hold of a Citronic AC-1USB gadget to convert my tapes to digital. I'm coming out of my tape deck (stereo RCA L&R) into the Citronic interface (again stereo RCA) and into Audacity. Even with no signal, I note that when I click on monitoring the meters are flickering and there's some kind of audible inteference. To compensate for this I have the Recording Level triangle practically all the way to the left and the input dial turned up high on this Citronic to raise the gain at that stage. Is this standard practice? Doesn't seem right somehow. Where should the Recording Level Meter in Audacity be set ordinarily? Is there a default setting?

[steve]

It's quite common for Windows to set the level for USB devices very high. It's probably because Windows thinks the device is a USB microphone, so it sets the number of channels to 1 (mono) and adds a load of "gain" (boost) to the signal level.

Look in the Windows Sound Control Panel to check that 2 channels are enabled, and also have a look for any "enhancements" that may be enabled. Windows sound enhancements normally need to be disabled for recording. (see http://manual.audacityteam.org/man/faq_ ... hancements). There may also be a "+30 dB boost" option - if there is, turn that off.

Where should the Recording Level Meter in Audacity be set ordinarily?

Generally you would want to adjust the recording level so that the waveform reaches up to about half the track height (peak at about -6 dB on the meters). For live voice / music recording where the sound level may be erratic, you would probably want to aim a little lower for safety. It is essential that the recording level stays below 0 dB at all times. Digital recording "clips" at 0 dB, which is permanent and often unrecoverable damage.

[7track]

Thanks so much for your respose. Yes, Windows is seeing this Citronic audio capture device as a 'USB Microphone' and the default is one channel 'mono'. I'll go and have a look 'behind the scenes' now and see what else has been enabled that might need disabling. Thanks so much!

[7track]

Still not out of the woods this end it appears! Even with my laptop just running on battery power (ie: no mains 'interference') I can't seem to get rid of the 'static' or whatever it is! As soon as I fire up Audacity (with this 'CITRONIC AC-1USB' USB-powered interface connected) then click 'Monitoring' there's this flickering signal on the level meters (which you can see in the attached screenshot with inserts). NOTE: This is without an input source signal connected/present, the flickering is there from the off. If I turn up the recording level triangle it gets even worse. I'm managing to record audio in (from my tape deck line outs) but it's not a 'clean' signal - there's this constant static in the background. Is there anything else I can perhaps try here?

PS: No drivers were required for this unit. My laptop just recognised it instantly on plugging in.
PPS: UPDATE! In an attempt to troubleshoot this further I now appear to have permanently disabled other options in the 'Sound' section of my PC's Control Panel! I thought by disabling: Ext. Mic/Internal Mic (and, err, 'something else' "YIKES!") it might take troublesome factors out of the equation but all the things I mention in the above sentence now appear to be gone for good on my system = "ARRGGGHH!!!"

[steve]

I'm coming out of my tape deck (stereo RCA L&R)

Is there an output level control for those outputs, or is it fixed "line-level"?

[7track]

The tape deck outs (L/R RCA marked 'LINE OUT') are line level. There's a gain trim level on this Citronic unit which I have set to about half way. Like I say though, there's the flickering on the meters in Audacity WITHOUT the deck (or any input source) attached. If I remove the interface it goes away but, as soon as the interface is reconnected and I click 'Monitoring' the flickering meters come back. Here's a link to this Citronic unit - it all looks/seems very straightforward (in theory!) and that's the main reason why I bought it as I didn't want anything too 'fancy' to confuse issues. Hmm ...

[steve]

OK, so you've got::

1) Tape player:
Fixed output level.
Fixed noise level (dependent on tape noise).

-> going into ->

Citronic:
Adjustable input gain level -> A/D converter -> USB ->
Noise level may change with gain level.

-> going into ->

Computer:
Adjustable input level (digital) -> Recording application (Audacity).


It's important that the signal does not clip at any stage, but in order to minimise noise we also want a reasonably high signal all the way through the signal chain.
Ideally, the gain on the Citronic should be as high as possible without clipping as it passes through the A/D converter (analog to digital). This will give the best signal to noise ration ("SNR") for the (digital) signal that is going into the computer.

Does the Citronic have a "clip" indicator (to show when the gain is set too high)?

[7track]

Yes, aware of gain structure. My decks sending a line level. I can control the gain with the trim on the interface (it has a clip gain LED that turns red if the input source is too loud which it's not in this example). I click on 'Monitoring' in Audacity and there it is, a garbled static sound and the meters jumping about (as is shown in my above attachment). If I go and hit play on the deck now I AM getting a signal and I can record the input HOWEVER the underlying 'static garble' is still present (especially noticeable on quieter passages and at the start and end of the music I am attempting to digitise). I've tried it now with a CD player as my input source and, as mentioned, without any input source connected and the interference just won't go away. Not really sure where to go next with this as there doesn't appear to be any options left to me the way I see it - I've tried everything I can think of. (Thanks again for your help in this matter too of course). I'm kind of stumped now this end!

[Gale Andrews]

The tape deck outs (L/R RCA marked 'LINE OUT') are line level. There's a gain trim level on this Citronic unit which I have set to about half way. Like I say though, there's the flickering on the meters in Audacity WITHOUT the deck (or any input source) attached.

Why would you expect inputs to be noiseless?


Gale

[steve]

it has a clip gain LED that turns red if the input source is too loud which it's not in this example

Good.
Play the loudest tape that you own, turn up the gain until the LED just comes on, then back it off just a little so that the LED does not come on.

Now Launch Audacity and adjust the record level so that the peak level is around -6 dB (half track height).

What's the noise level like now? (there will always be 'some' noise from the audio device, but it should be low level).