speakers erasing tapes

how close would a 1/2" tape have to be to a standard bookshelf speaker for it to have an effect/erasure or otherwise?

For the average bookshelf speaker - ie not a hulking great magnet - pretty damn close in reality, but that said I wouldn't feel comfortable placing it less than about six feet away.

Mmmm, not sure . .


  All I can say is that when I worked for Roger Quested, I went through half a dozen bank cards a couple of years  . . .they would just stop working in cashpoint machines. I could only conclude that it wuz da magnets wot dun it . . and I never knowingly sat on a bassdriver or midrange . .


  ANdyP

only time I ever really had any magnetic material erased was using the bulk tape eraser and the time I de-maged a tape machine with bank cards in pocket.

I found a  slap echoreel of tape near a set of mains once that played without issue although I don't know what was supposed to be on there. I for one wouldn't take any chance....

It's kinda OT, but I once left a set of cans on my laptop and totally crashed the HD...

My dad left a box of cassette tapes (with recordings) on top of the TV for 6 months (mid '80's), and they were almost entirely blank when played. 

emrr said:

My dad left a box of cassette tapes (with recordings) on top of the TV for 6 months (mid '80's), and they were almost entirely blank when played. 

Click to expand...

Old school color TV picture tubes used a degaussing coil (once every time they turned on) to demagnetize the picture tube and prevent color distortions. Your cassettes were apparently degaussed... which is just like a bulk tape eraser.

I suspect the popularity of VCR tapes, stored in the vicinity of TV monitors caused them to be a little more careful with stray magnetic fields.

JR

Reading through this thread made me realize how close I've probably come more than once to erasing all my bank cards, letting my wallet lie around while using the tape demagnetizer... Thankfully nothing happened so far.

My wife had a purse with a magnetic fastener. Was enough to kill her bank card. I've actually considered making a bank card sheath out of mu-metal. Wouldn't help against the demagnetizer though.

spreemusik said:

My wife had a purse with a magnetic fastener. Was enough to kill her bank card. I've actually considered making a bank card sheath out of mu-metal. Wouldn't help against the demagnetizer though.

Click to expand...

Didn't the mythbusters utterly debunk this myth? It's completely impossible to erase any type of bank cards with magnets, new or old. People just think it happens, but it is actually physical wear that breaks the cards. Magnets have nothing to do with it.

Well, it worked before the new purse, then it didn't. But apparently the quality of bank cards has drastically worsened. I do have a couple of old ones, and lots of magnets, so I could experiment. Just have to find a card reader.
While on the subject of experimenting, and back on topic, has anyone actually tried erasing tape with a permanent magnet?

Mythbusters have debunked your mamma. Kingston, you don't even exist, haha.

spreemusik said:

While on the subject of experimenting, and back on topic, has anyone actually tried erasing tape with a permanent magnet?

Click to expand...

It works, but doesn't make a lot of sense. You need a high frequency bias to get good SNR, and the frequncy of a permanent magnet is essentially zero.

living sounds said:

spreemusik said:

While on the subject of experimenting, and back on topic, has anyone actually tried erasing tape with a permanent magnet?

Click to expand...

It works, but doesn't make a lot of sense. You need a high frequency bias to get good SNR, and the frequncy of a permanent magnet is essentially zero.

Click to expand...

It works; it was used on some cheap machines. High frequency is necessary for bias, not for erase.

abbey road d enfer said:

It works; it was used on some cheap machines. High frequency is necessary for bias, not for erase.

Click to expand...

Yes, but the bias frequency is fed to the erase head as well for the best results.

living sounds said:

abbey road d enfer said:

It works; it was used on some cheap machines. High frequency is necessary for bias, not for erase.

Click to expand...

Yes, but the bias frequency is fed to the erase head as well for the best results.

Click to expand...

HF erase has no direct influence on the quality of recording.
DC erases tape as well as HF, but leaves permanent magnetization on tape and also on erase head, which in turn magnetizes the heads. The record process is essentially not affected, because as soon as bias current is established, the record head gets demagnetized, but the playback head gets stays magnetized, as well as rollers and guides. As a consequence, the fresh tape gets magnetized by contact, and that creates awful thumps and noises. This remanent magnetization also partially erases high frequencies of existing recordings, making them muffled.

so you think my bookshelf speaker will magnetize the play heads, rollers and guides?
really?
from what distance?
presuming i have an ns10 mounted 20" from the play heads for instance...

I wouldn't take the chance...Do you demag your tape machine everyday?