Recording K7 Tapes

[Clipping]

Im about to digitize around 1.000 hours of testemonials recorded on K7 tapes. The oldest tapes has around 20 years and the newest around 7 years. They roll foward and backwards each tape each 6 month.
- Is there any standart procedure before playing them? Like an equipment for cleaning the tapes?
- Suggestion for a good equipment to play the tapes?
- Where do I find a good equipment to fix broken tapes?
- How often should I clean the player heads? Each tape? Isopropilic alcool still the best?
- What can I expect from the sound quality of these tapes? I didnt listen to them and have no idea of the sound quality. Since the tapes were recorded very close to the speaker they might had suficient sound quality at the time they were recorded.

[Craig Maier]

What is a K7 tape? I vaguely remember hearing about a model K7 Magnetaphone tape recorder, but I do not think that is what it is that you are discussing. Is that the kind of tape recorder that is/was used in legal proceedings in which the head oscillated up and down?

[cromag]

Clipping, are you French?

The word "cassette" in other languages

The word "cassette" is French in origin, so it was acceptable to the Acad?mie fran?aise. A popular alphanumeric abbreviation comes from the word's pronunciation /ka ˈsɛt/ in French, which is the same as that for K7 in that language. The same holds true for Catalan. In Portuguese, the abbreviation K7 works as well. In Spanish it is popularly abbreviated by the letters KCT (pronounced /ka ˈsɛ tɛ/).

[Dan McDonald]

Hadn't even thought of that... I was wondering also.

case - sept


You learn something every day.

[Craig Maier]

If the tapes in question are Cassettes, here are my suggestions:

- Is there any standart procedure before playing them? Like an equipment for cleaning the tapes?

Clean the Tape Deck Heads, Capstan, and Pinch Roller before playing. Also, demagnetize the heads. Make sure that the tapes are located far away from the tape deck during the demagnetizing process. Make sure that the tape head azimuth alignment is correct. DO NOT ATTEMPT TO CLEAN THE TAPE, PER SE.

- Suggestion for a good equipment to play the tapes?

Any high quality tape deck, usually indicated by the fact that it will have three (rather than two) heads.

- Where do I find a good equipment to fix broken tapes?

Tape Splicing Equipment can be purchased at Radio Shack; at least they had it a few years ago.

- How often should I clean the player heads? Each tape? Isopropilic alcool still the best?

You should clean the heads after each tape play since the tapes are so old. Isopropyl or Ethyl Alcohol are good solvents for this. NEVER PUT ALCOHOL OF ANY SORT ON A TAPE. IT COULD DISOLVE THE BINDER RUINING THE RECORDING.

- What can I expect from the sound quality of these tapes? I didnt listen to them and have no idea of the sound quality. Since the tapes were recorded very close to the speaker they might had suficient sound quality at the time they were recorded.

That would be hard for me to say. Anything and everything is possible.

[cromag]

Cross your fingers!

I've "restored" several cassettes from my personal collection. These run up to about 25 years old, but they were pre-recorded (or home recorded by me) so they had a reasonably good signal to begin with, and were reasonably well cared for. In these cases there wasn't much restoration to do, although I had a lot of fun using different tools to enhance what was there -- especially if the artist wasn't high on the recording company's list of priorities.

I've shied away from picking up used cassettes at the thrift shops, though, since most of the ones I've seen show obvious signs of abuse and neglect. I picked up a few, but only to hold me over until I can locate a good copy, or an LP. I'll start playing with them when I get the time.

From what you've said, Clipping, it sounds like the tapes have been well maintained and contain spoken word rather than music. As long as they were reasonably well recorded you might luck out!

[Dan McDonald]

I work with cassettes all the time - up to about 35 years old, not pre-recorded and get extremely good results. Just take your time on the cleanup. Follow Craig's suggestions for transferring. Use 24-bit transfer if you are able because you'll need to do quite a bit of work on them, but I usually can eliminate nearly all the hiss without hurting the music or whatever is recorded.


If they've been taken care of, as cromag mentioned, you should get good results. I've gotten decent results from 50 year old open reel tapes, but 30 year old cassettes should result in very nice end products.

[Craig Maier]

Cassette Tape Inspection Before Playing

Probably the most important thing that one should do with a rare and/or old Cassette tape is the inspection process before proceeding to "pop" it into the machine. Here is what I do, especially to 30 year old living history Cassette tapes:

1. I make sure that the record protection tab is removed.

2. I check the pressure pad to be sure that it is still there. Sometimes, these things fall off because the glue fails. If it has fallen off, I canabilize another tape having no particular value and retrieve its pressure pad. I replace the missing one with the canabilized one. Sometimes, I just glue the felt part onto the phospher-bronze spring assembly, or if the cassette is screwed together, I take the assembly apart and replace the entire pressure pad / phospher bronze assembly.

3. I use a pencil held at a slight angle slid into each reel - - - one at a time. I assure that the tape moves freely in each direction by spinning the pencil. The reason for this is that if the tape has internal tension and is binding, the tape machine may have enough torque to stretch the tape causing irrepairable damage (well, the curvalinear speed change filter can be used to fix this, but it best not to get into this situation to start with). If the pencil requires a lot of force, I stop the process. Then, I take apart the tape and find out what is causing the binding and fix it before playing.

4. I always use a pencil to take up all slack in the reels. If tapes have been laying around loose in a drawer outside of the cassette carrier / jewel case, the tape can become partially unwound. Taking up the slack before placing the tape in the machine is a must. Otherwise, you run the risk of wrapping the loose tape around the capstan and or pinch roller thereby tearing and crinkleing / creasing the tape.

keywords: priceless cassette tapes, cassette tape preparation

[DougMac]

Another Caution

Sometimes the splice to the leader fails. You'll get to the end of the tape and it will just keep going.

Our friends at Tracer sells repair materials: http://www.tracertek.com/miva/mercha...tegory_Code=TR

Also, if you can find old BASF cassettes, they screwed together. They make great repair housings.

If you can get an autoreverse deck, you can combine that with DC 6's VOX feature to make the transfer an unattended affair. I'm wondering if the cassettes in question or unidirectional or biderectional.

On a side note, it's too bad they didn't take the technology used to wring out decent sound from a cassette and apply it to the reel to reels of the time. I just listened to a Pete Fountain commercial RTR recorded at 7 1/2ips. I've heard commercial cassettes that sounded as good, if not better.

Doug

[Craig Maier]

The key technology that improved the performance of the Cassette Deck over time involved the reduction of the tape head gap in conjunction with tape formulations having finer coloidal partical size. It is a very good question why they did not do the same thing with Reel to Reel tape decks. Perhaps it involved the existing standards in the Reel to Reel industry since the EQ circuitry would have had to have changed too.

[Clipping]

Cassete Tapes Frquent Noises

I believe that hiss will be the most frequent noise I will find in these testimonials speech cassete tapes. I will use CNF will solve this problem. Correct?

Is there any other frequent noise I might find in these tapes?

Several tapes have recorded some seminars and there are speech echos, people speaking far from the microfone, etc.
- Is there a filter I can use to remove echos?
- People speaking far from the microfone how can I make their voice more clear?

Thank you all, your help and coments, they were great.

[Dan McDonald]

I use the CNF quite a bit with cassettes and it works well. You should be able to use the EZ clean also.

Hum (60 Hz or 50 Hz, depending on where you live) is sometimes a problem, depending on a lot of factors.

There is the Dynamics Processor "Telephone conversation near-far" presets that might help with the far from microphone problem, if some people are close and some people are far. If it's a matter of being far for an extended period of time, just boost the gain in that area and you can get a little more aggressive with the CNF - background noise will increase also.

Echo is very difficult to get rid of. I had a little success in making mono recordings into stereo ones and subtracting one channel from the other, but you have to get the delay exactly right, and you have to work with the level of the one you're subtracting so that it's not as high as the source. Even then, I have only done this with something that I really want to keep (priceless stuff) because it is a huge amount of work.

Dan

[Craig Maier]

Just as a quick sidebar, the Dynamic Spectral Subtraction filter in the Fornensics version has been known to be effective for the reduction of echo. But, that is only available in the more expensive software package.

[Dan McDonald]

That's interesting. I believe I tried the DSS with some music tapes but it didn't help much. Of course, not much could have helped these tapes. I may not have been good enough at it. I should try that again.

[Craig Maier]

I have never tried DSS (Dynamic Spectral Subtraction) on music tapes. It was really designed for speech (spoken word) and Forensics situations primarily. I suspect that the DSS would produce a lot of artifacting on music, but I do not know for sure.