Oh well... My babe (ITC Delta) while playing and recording normal stuff behaves apparently nicely. But, while recording single tones @ a fixed level shows +1/-1 db oscilations about 3/4 times per second. Any clues about what it might be? Note that it's just the level, not the frequency (that excludes capstan motor issues, I think)...
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Analog audio recording -issues
- Thread starter SFM-Ptgal
- Start date
I
Info-warrior
Guest
Rock the level trim pots back and forth a bit. They might be dirty.
Could be worn tape heads.
Heads, guides, or carts, or some combination thereof are probably worn. Level variations at playback only are a function of changing tape wrap across the head gap. And quite common, it ain't easy to get a continuous loop to pull past a head straight and at constant tension.
I forgot to add - this can also happen if the head face isn't exactly perpendicular to the tape path...causing the tape to ride up and down as it passes the head.
littlejohn said:
Thank you all. I wrote b4 that it's playback issue only. I'm wrong because it happends on all the players, so I assume that's a recording issue. About the tape "deviation" it's not a problem because while summing the channels I don't get any phase issues... And the heads are flat as a pool ball ;D
SFM-Ptgal said:
WHAT ???
They are supposed to be round!
What kind of response do you get when you hit (pun intended) a cart with a high frequency like 10 kHz?
R
Robert Bass said:SFM-Ptgal said:
WHAT ???
They are supposed to be round!
What kind of response do you get when you hit (pun intended) a cart with a high frequency like 10 kHz?
R
0 db@10Khz input= almost steady 0 db@10Khz on the tape monitoring level output. No phasing issues noticed.
SFM-Ptgal said:Robert Bass said:SFM-Ptgal said:
WHAT ???
They are supposed to be round!
What kind of response do you get when you hit (pun intended) a cart with a high frequency like 10 kHz?
R
0 db@10Khz input= almost steady 0 db@10Khz on the tape monitoring level output. No phasing issues noticed.
SWEET! 8) 8) 8) 8) 8) 8)
If you get similar results with 1 kHz and 100 Hz, you've got yourself a correctly callibrated machine!
And in that case, a +/- 1 or 2 dB "wavey" tone is not really that big of a problem. At least not to me, it isn't. The phase alignment is more important, and it sounds like your machine is in very good condition.R
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.
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.
frankberry said:
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 said:Thank you all for the replies. Since it's a minor imperceptible problem I can live with it
If it ain't broke, don't fix it, eh?
R
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.
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.
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