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Tape Trail Reel to reel, cassette and other analogue tape formats. |
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Tape Trail Reel to reel, cassette and other analogue tape formats. |
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In Reply to: Re: Playback Equalization posted by kingseiko on May 13, 2005 at 18:50:54:
I don't think you mean Type I bias for playback. Bias is a high frequency signal applied to the tape along with the music signal during the recording process. It is true that the recording bias for Type II tape is approximately 50% higher than for Type I tape. The recording bias for Type IV metal particle tape is higher still. Bias does not apply to the playback equalization curves previously described in this thread.If your deck has an external bias adjustment trim control, you can adjust the recording bias by ear for a particular type of tape. When the bias level is properly set, for the type and brand of recording tape you are using, the playback of a test signal such as pink noise or interstation FM radio hiss (recorded at a level of -20DB without noise reduction) will be almost indistinguishable from the source signal.
If the bias is set too low there will be excessive high frequency response and increased distortion. If the bias is set too high the recording will be rolled off in the uppermost frequencies and sound dull in comparison to the source test signal. It is easier to adjust the recording bias if the deck has separate recording and playback heads, and allows off-the-tape monitoring during recording. But if the deck has only a combined record/playback head you can still adjust the bias with a bit more effort and time. Just record 30~60 seconds of test signal for each setting of the bias control, making sure to write down where you started with the setting of bias control as you go. The important thing is to match playback level of the tape with the test signal as closely as possible, so you are not fooled into thinking that the louder signal sounds better.
If your supplier told you to use 120usec playback equalization for a Type II tape, this will make the recording sound overly bright in the frequency range of 2000Hz and higher. Perhaps your tape supplier is using high-speed duplicating equipment that introduces noticable roll-off of the high frequencies during the duplication process. So using the Type I equalization may be an attempt to restore the frequency response of the recording, but nothing is for free as this will also increase the level of any noise in the recording during the playback of the tape. This may be acceptable for playback in a moving vehicle where road and engine noise will usually mask any noise in the recording.
Many current decks automatically sense the cutout notches in the cassette shell and set the recording bias and playback equalization accordingly, with no ability to override these settings.
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Follow Ups
- Re: Playback Equalization - mkmelt 22:26:41 05/13/05 (3)
- Re: Playback Equalization - kingseiko 07:17:39 05/14/05 (2)
- Re: Playback Equalization - mkmelt 11:40:30 05/14/05 (1)
- Re: Playback Equalization - Tandberg TD20A man 14:09:59 05/14/05 (0)
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