Test –Qview Magnetic Developer for Tape Imaging
Magnetic imaging can be a valuable tool in cassette tape restoration by providing a non-invasive way to visualize and analyze the magnetic patterns on the tape. This is particularly useful for:
- Diagnosing Issues: Magnetic imaging can reveal problems such as uneven magnetic fields or areas where the magnetic particles have degraded, which can affect audio quality.
- Forensic Analysis: It can help authenticate the age of recordings or detect tampering by comparing the magnetic patterns to known standards.
- Data Recovery: For damaged tapes, magnetic imaging can assist in recovering audio data that may not be retrievable through conventional playback methods.
- Preservation: By understanding the condition of the magnetic tape, conservators can make informed decisions about the best methods for preservation and storage.
The Process of Making Images
Record a signal on the tracks you want to develop at a high level, a square wave, and a low frequency.
If you want to measure the signal on the tape, the frequency needs to something like cycles/mm at tape speed. for example to image cassette tape the length of tape per second is
4.8 cm/sec = 48 mm/sec
to place a edge line of a square wave on every mm you would need to consider two edges per square wave, so divide by 2 = 24 Hz signal
Record about ten seconds and then center the tape at the five second mark.
Tape the magnetic tape, magnetic side up, to a piece of graph paper in millimeter divisions. I use sticky notes to secure the tape. Then place a few drops of the developer on the tape and allow it to dry. Then either photograph the page with a good macro camera, or place it on a scanner and scan the tape at the highest resolution.
The illustrations below show the process.
After imaging the tape, wind it forward and save the tape for future use. Don’t play the developed portion of the tapeunless you wipe the iron particles off.
The detail image shows better how this looks . I made new traces at 24 Hz. the illustrations below show my first set of tests which i did at 4.76 cm/sec tape speed – which is not correct for japanese decks .
After putting a few drops of Qview on the tape, let it dry and then image it on the scanner. There is no need to cut the tape out of the cassette. After getting the scan, wind the tape back into the cassette shell on the take up side. You can use the tape over and over to make images, just don’t rewind to the part you already imaged because there may be some residual sticky from the sticky notes that might foul the rollers or heads, or cause the tape to jam
Conclusions
Concluding comments
1. This page was done engineering notebook style – Someday in the future it might be added to and typed up in a spreadsheet
2.This is a current system ‘Standard’ subject to revision.
As always there is also:
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.
Pingback: Added Qview Mag Imaging to Test - Carl Valle ORG
Had to revise this page – Japanese decks do not run at the same speed as european decks do. I checked service manuals for the decks in my system:
TEAC
TASCAM
JVC
Technics
and they all say 04.8 cm/sec
So i revised this page and revised the standards page