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I am finding lots of pre-recorded tapes with nothing on them about what bias or eq they were recorded at or what type of tape was used. Do any of you folks have any "rules of thumb" for unmarked tapes? I'm guessing there must be some based on year recorded, recording company, type of music, etc?
Thanks
Vince
Follow Ups:
For pre-recorded cassettes with no eq given on the cassette itself, my best bet is to set the eq for 120 (forget about the bias)and give it a listen. If it sounds bad try 70 before I toss it. Does that sound about right? Thanks for all the info boys & girls, I apprciate it.
Vince
as well. If it's too bright with 120, it's a 70. Same if it's too bright with Dolby off, it's Dolby on and should have the double D face to face sign somewhere on the label, the cassette itself or the box/printed material.
I am confused by the "small and large notches" y'all keep refering to. On my pre-recorded cassettes there are two notches of equal size on either side, that's it.
Maybe I can help to clarify. A cassette tape shell can have as many as three pairs of notches, knockouts, detector slots, or whatever we want to call them. The outboard most pair is to prevent accidental erasure of the tape. Blank tapes have tabs to break out of this location after the tape is recorded. Prerecorded tapes, it is already out obviously. Just inboard of these is the next pair of slots. These are open if the tape is Type II (70 uS), no opening for Type I (120uS). Many cassette decks have sensors to automatically select the proper EQ based on these notches. The third pair of notches is much closer to the center of the top edge, about 1/2 inch apart from each other. These slots are open on Type IV, or metal tapes.So, if your machine does not have automatic tape type sensing, and the prerecorded tape does not have any other indication, just check the number of open tabs on the tape, and set the EQ accordingly :-). HTH
Are these notches on the wide edge where the tape touches the heads or on the narrow edge opposite that?
They're on the narrow edge opposite where the tape contacts the heads.
Mike
Thanks Mike, that's an easy to follow system. I can see that virtually all my prerecorded cassettes are 120 eq as almost all have only the outboard pair of notches. I like your system.
Thanks
Vince
which my rich and cheapskate uncle used to punch out to get SVHS performance with cheap tape.
Bias is only applied in the recording process. Playback is never adjusted as to bias. As to EQ most pre-recorded reel to reel tapes in the USA are NAB. Most European tapes are CCIR. Nagra has a unique equalization scheme but hardly no pre-recorded tapes were made with it. It was used primarily with film sound on location with Nagra recorders. As to tape formulation, every company had their own "deal". Ampex used AMPEX tape. Capital used AUDIOTAPE. Many companies were into making audio tape in the 50-80s; Irish became Ampex, Kodak made tape for a short time and then the European companies Agfa and Basf. Basf sold a lot of cassette tape. Most studio mastering was done on Scotch 111 until about 1967 then back coated tape came in with "low-noise" 202, 206. Ampex with 406 then 456. Bias was set to 0db and not overbiased until the "low-noise" tapes with finer oxide and higher coercivity demanded a slight overbias by about .5 to 1 db. Ray
"I take you as you are
And make of you what I will,
Skunk-bear, carcajou, bloodthirsty
Non-survivor.
Lord, let me die but not die out." THE LAST WOLVERINE by James Dickey
For cassette tapes, if the recordings are based on 70uS equalization you should set the equalization on your deck to 70uS instead of 120uS during playback. This has been clearly indicated on the J-inserts that come with the cassette tapes that are recorded using 70uS.For example, in a PRO-ARTE pre-recorded cassette tape, on the J-Insert it states:
" Duplicated on Chromium Dioxide Tape, Requires 70uS Eq. "
For Reel to Reel I do not know though.
So what eq are you suggesting I use for pre-recorded cassettes when there is nothing on the tape?
120uS Eq.
Hi:
There is in general three types of pre-recorded cassette tapes in the market. One of the three is Type-I( or normal ) with 120uS equalization. This is the most common seen one. The second one is Type-II ( or Chrome ) with 120uS equalization and the third one is Type-II ( or Chrome ) with 70uS equatlization. Seldom will you get Type-IV ( or Metal ) with 70uS equalization.The first two will need to be played under Type-I and 120uS equalization during playback while the thire one will need to be played under Type-II and 70uS equalization during playback.
I have no idea whether when you play a Type-II with 120uS equalization tape on a deck which allow you to select the tape type plus bias manual you have to select normal and 120uS or CrO2 and 120uS even though the J-insert in the pre-recorded casssette tape will tell you to use normal and 120uS during playback. The type-tab on the shell for Type-II with 120uS equalization is the same as the Type-I shell ( one single tab ). This probably is to ensure that normal and 120uS equalization will be selected on those decks that automatically select the type of tapes for you.
In general, pre-recorded commerical cassettes will have much better playback performance when recorded using TYPE-II/70uS equalization. They are not produced as many as the TYPE-II/120uS though.
Pre-recorded commerical cassettes using TYPE-IV/70uS are very rare and as far as I know only the Reference Recordings by Nakamichi series exist. Let me know if there is more brands than this one.
Hope this will help.Happy Hunting,
Mike
On Reel to Reel both bias and EQ are record only functions and these switches on your deck have NO effect on playback.On Cassette bias is a record only function however Cassette has two playback EQ settings: 70ms and 120ms, choosing the incorrect one will make the recording sound either too dull or too bright.
Basically if a pre-recorded Chromium dioxide cassette says “Compatible Chrome”, “120us Chrome”, or just “Chrome” with only the small notch removed on the top of the headshell it is 120us EQ (Normal).
If a pre-recorded Chromium dioxide cassette says “70us Chrome”, or just “Chrome” with the large notch removed on the top of the headshell it is 120us EQ (Chrome/Metal).
"Music is love"
Teresa
but muS--lowercase μ and here refers to microseconds
Mu is the 12th letter of the Greek alphabet.
to: 70μS and 120μS.Maybe it thought it was "ms" because it stands for microseconds?
"Music is love"
Teresa
I think I have been calling it "ms" for decades when my cassettes clearly say "uS" or "us". I don't know where the "ms" comes from other than my salutation.Please if anyone sees any errors or typos on my web site me know at info@analoglovers.com.
Teresa:
I hope it is only a typo. If a pre-recorded Chromium dioxide cassette says " 70uS Chrome " or " Duplicated on Chromium Tape, Requires 70uS Eq " with the large notch removed on the top of the headshell it requires 70uS EQ ( Chrome/Metal ) setting during playback in your deck.Correct me if this is not true.
I will change all reference on my web site from "ms" to "uS", great catch.I found another error the other day I have "Direct to Tape Recording Company" listed as "Reel to Real recording company". Reel to Real was a company that sold pre-recorded Reel to Reels.
If anyone else sees typos or errors please email me at info@analoglovers.com.
"Music is love"
Teresa
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