TI = Record tabs in
TO = Record tabs out
NR = Normal bias recording, 120 µs EQ playback
CR = High bias recording, 70 µs EQ playback (for chrome or cobalt tape)

Many people put chrome or cobalt tape into normal shells. To do this you MUST have a cassette recorder with a BIAS Selector button.
You will not be able to record correctly on later-model cassette decks which use an auto-sensing pin to determine the bias and EQ.

TABS IN or TABS OUT

Note: Most of our cassettes are TABS OUT (check out tabsout.com for a cassette podcast) and for normal bias tape. If you want to record on regular cassette decks you must put a piece of scotch tape over the record tab holes, or choose the TAB IN cassettes... or disable the record tab sensor on your machine with some duct tape or a paperclip!

Notes:

• TI = Record tabs in, any machine can record on these tapes
  
  
• TO = Record tabs out, for duplicated cassettes or professional machines, you can record on these tapes if you put some scotch tape over the hole or if you use professional duplicators.
  
  
• NR = Normal tape (aka Type I tape or ferro), machines record and play back with a 120 µS equalisation curve.
  
  
• CR = for high bias tape (chrome or cobalt), has an extra notch to tell the record machine to use higher recording bias and to use 70 µS record and playback EQ. One of our tricks is to use standard normal bias cassette shells with high bias cobalt or chrome tape, and a special equalisation during recording. This lets us have louder and brighter cassettes.
  
  
• Type IV = c-zero has a notch for metal bias
  
  
• Screws: the two halves of an audio cassette shell are either held together with 5 screws, or are sonic-welded with no screws. One type is not neccessarily better than the other.
  
  
• Liners: also known as slipsheets or foils, every cassette has liners to support the tape hubs. The tape liners play a critical role in permitting a smooth rotation of the tape hubs. The liners are rippled to apply a slight spring pressure on the tape hubs.
  
  
• Pressure pad: The pressure pad is a wool pad mounted on a spring and applies pressure on the tape as it passes over the recording and playback head.
  
  
• Leader tape: every C-zero has about 15 to 20 seconds of leader tape. The leader tape is usually a clear, frosted, red, or blue-tinted plastic. You cannot record on the leader tape.
  
  
• Magnetic leader: We also have cassettes loaded with magnetic leader tape to permit instant-start recording. For example court reporters may want instant start cassettes so they don't miss a word.
  
  
• Rollers: Most C-zeros have a roller in each lower corner to guide the tape. Rollers that are out-of-round cause wow in the recording. Rollers that are not precisely made can also cause azimuth problems. Some cheap cassettes did not have rollers.
  
  
• Guide posts: Most C-zeros have guide posts located before the rollers to help isolate fluctuations in the supply and takeup hubs from causing wow and flutter in the recording.