Analog audio recording -issues

[frankberry]

The problem may be due to some very low frequency oscillation.  Check the decoupling caps in the power supply.

Also.  Recording a 10kHz signal at 0dB does not generally produce a 0dB output on playback due to the high frequency compression that is normal in the analog tape world.  I have always recorded the 10kHz tone at a level of -10dB.  At that level, the tone should play back at -10dB because the level is below the high frequency saturation point of the tape.

[Robert Bass]

Also.  Recording a 10kHz signal at 0dB does not generally produce a 0dB output on playback due to the high frequency compression that is normal in the analog tape world.  I have always recorded the 10kHz tone at a level of -10dB.  At that level, the tone should play back at -10dB because the level is below the high frequency saturation point of the tape.

Hmmm, well both of my decks are giving me a near 0 dB reading during playback of a 10 K tone recorded at 0 dB.  Perhaps the machine(s) you worked with were not in pristine condition?

R

[SFM-Ptgal]

Thank you all for the replies. Since it's a minor imperceptible problem I can live with it  Perhaps I'm being too picky 

[Robert Bass]

Thank you all for the replies. Since it's a minor imperceptible problem I can live with it  Perhaps I'm being too picky 

If it ain't broke, don't fix it, eh?

R

[Tom Wells]

But still,  inquiring minds want to know!

 I'm betting on the low frequency oscillation from the power supply.  Here's why:

Do you have any tapes with test tones from another machine and do they also show the 1 db flutter on playback?
It may be that it really is putting the variation in at recording, but not indicating on the meters during record.
High frequencies may be beating with the recording oscillator if the osc is not completely decoupled.
The ONLY mixing of  the audio with recording bias freq should be at the HEAD.
Try adding some more filtering caps temporarily and see if it clears up.