Anyone ever send a track to a tape recorder then back?

[NYMorningstar]

actually you demagnetize the tape player heads.. not the tape itself.

After you demagnetize the tape player heads and then turn them on aren't they magnets again? What did demagnetizing the heads accomplish exactly? I was taught to only demagnetize the rollers and guides and not the heads.

 

[tthcore]

I used to be really into Lo Fi stuff. I'd record on a PC then run it through a tape deck to get the 'hiss'.

 

[liv_rong]

you can demagnetize the tape...Thats what the entire degaussing room was for

If the client started fooling around about payment, you walked over to the degaussing machine and stuck the tape on it and started counting. Usually be the time you hit 2 or 3 they'd have some money

hahaha, thats brutal!!

 

[metalhead28]

I would imagine that sending to a cassette deck would add the "tape sound" in much the same way that tracking through this:

...would yield the "tube sound"

 

[liv_rong]

but its "ultragain" and it says "tube" on it

 

[TerraMortim]

After you demagnetize the tape player heads and then turn them on aren't they magnets again? What did demagnetizing the heads accomplish exactly? I was taught to only demagnetize the rollers and guides and not the heads.

excess buildup of flux on the heads happens since so much tape runs by on them over time.. It can bring up the noise floor.

 

[NYMorningstar]

excess buildup of flux on the heads happens since so much tape runs by on them over time.. It can bring up the noise floor.

I apologize in advance, I have too much time on my hands today

Are you saying the flux buildup is from the tape?

The way I understand it is the tape heads are made up of soft magnetic material which has essentially no coercivity or retentivity. That means they do not retain magnetization and they follow the strength of the applied external magnetic field.

On the other hand, hard magnetic materials have significant coercivity or retentivity which is why their used for storage.

I understand removing the buildup of residue(hard material) off the heads using alcohol and a soft cloth or a q-tip but removing magnetic flux I'm still not getting. Isn't the bias current added what determines the balance between distortion and frequency response? Does this flux buildup really affect noise floor? Anyone know of any test results on this?

 

[SouthSIDE Glen]

Are you saying the flux buildup is from the tape?

The way I understand it is the tape heads are made up of soft magnetic material which has essentially no coercivity or retentivity. That means they do not retain magnetization and they follow the strength of the applied external magnetic field.

Yes it does come from the tape, and your description of tape is essentially correct also, but the two points are not mutually exclusive.

If tape didn't retain magnatism at all, it would be useless as a recording meduim. It is that very retention that allows it to work. When they say it doesn't retain it's magnetism very well, they're talking as compared to something like an iron magnet.

The magnetization of the heads isn't so much from the tape dust itself, but rather from the prolonged exposure of the heads to the magnetic fields on the tape itself.

Have you ever, when you were a kid, magnetized the tip of a paper clip with a magnet just by letting it stick to the magnet for a while (this is a classic way of making a homemade compass needle)? Just the prolonged contact to the magnet causes the clip to acquire some magnetic properties itself.

It's a similar principal with tape heads. Just the prolonged contact with the magnetic tape, over time, can cause a small build up on magnetism on the tape heads themselves (especially the playback head , which has no field of its own.)

As far as the noise, not only can the magnetism affect the performance of the playback heads, but they can serve to slowly erase the tapes themselves, like lightweight, lower magentism versions of an erase head. This can actually increase the noise level on the tape itself.

This is why there are indeed tape head demagnetizers of all different sizes and shapes (and levels of quality too) ffor everything from casette decks to 2" open reels.

G.

 

[NYMorningstar]

Yes it does come from the tape, and your description of tape is essentially correct also, but the two points are not mutually exclusive.

If tape didn't retain magnatism at all, it would be useless as a recording meduim. It is that very retention that allows it to work. When they say it doesn't retain it's magnetism very well, they're talking as compared to something like an iron magnet.

The magnetization of the heads isn't so much from the tape dust itself, but rather from the prolonged exposure of the heads to the magnetic fields on the tape itself.

Have you ever, when you were a kid, magnetized the tip of a paper clip with a magnet just by letting it stick to the magnet for a while (this is a classic way of making a homemade compass needle)? Just the prolonged contact to the magnet causes the clip to acquire some magnetic properties itself.

It's a similar principal with tape heads. Just the prolonged contact with the magnetic tape, over time, can cause a small build up on magnetism on the tape heads themselves (especially the playback head , which has no field of its own.)

As far as the noise, not only can the magnetism affect the performance of the playback heads, but they can serve to slowly erase the tapes themselves, like lightweight, lower magentism versions of an erase head. This can actually increase the noise level on the tape itself.

This is why there are indeed tape head demagnetizers of all different sizes and shapes (and levels of quality too) ffor everything from casette decks to 2" open reels.

G.

I never said tape doesn't retain magnetism very well. I said " hard magnetic materials have significant coercivity or retentivity which is why their used for storage."

I'm having a hard time understanding your perspective because it doesn't make sense that a tape head will buildup magnetic flux from tape when the head is in the presence of a stronger electromagnet and the material it is made of essentially does not retain magnetism. If at all, wouldn't the flux be from the stronger electromagnet?

 

[TerraMortim]

I apologize in advance, I have too much time on my hands today

Are you saying the flux buildup is from the tape?

The way I understand it is the tape heads are made up of soft magnetic material which has essentially no coercivity or retentivity. That means they do not retain magnetization and they follow the strength of the applied external magnetic field.

On the other hand, hard magnetic materials have significant coercivity or retentivity which is why their used for storage.

I understand removing the buildup of residue(hard material) off the heads using alcohol and a soft cloth or a q-tip but removing magnetic flux I'm still not getting. Isn't the bias current added what determines the balance between distortion and frequency response? Does this flux buildup really affect noise floor? Anyone know of any test results on this?

it's just what I was told. I don't work with tape that often, so dunno.

 

[Tim Gillett]

The tape head is not like a permanent magnet which is hard to demagnetize. It does have a magnetic "memory", but can be erased, like tape. Like a hard drive.

Often the head gets magnetised (becomes like a magnet with a north pole at one end and a south at the other) by big electrical switching spikes coming through the signal chain. It can happen to both the record and the play head.

The effect is a bigger noise floor, and erasure especially of the highs. Sometimes you can hear bass like thumps coming through.
Demagnetising is sending a powerful oscillating magnetism across the head but slowly diminishing to nothing. So each oscillation cancels out the last one until you arrive at no magnetic pattern on the head . No north or south poles.

On a well designed machine magnetisation of heads shouldnt get too bad but it was always good to demagnetize regularly as a precaution. Only took a minute or two.

Tim

 

[Tim Gillett]

The tape head is not like a permanent magnet which is hard to demagnetize. It does have a magnetic "memory", but can be erased, like tape. Like a hard drive.

Often the head gets magnetised (becomes like a magnet with a north pole at one end and a south at the other) by big electrical switching spikes coming through the signal chain. It can happen to both the record and the play head.

The effect is a bigger noise floor, and erasure especially of the highs. Sometimes you can hear bass like thumps coming through.
Demagnetising is sending a powerful oscillating magnetism across the head but slowly diminishing to nothing. So each oscillation cancels out the last one until you arrive at no magnetic pattern on the head . No north or south poles.

On a well designed machine magnetisation of heads shouldnt get too bad but it was always good to demagnetize regularly as a precaution. Only took a minute or two.

Tim

 

[SouthSIDE Glen]

I'm having a hard time understanding your perspective because it doesn't make sense that a tape head will buildup magnetic flux from tape when the head is in the presence of a stronger electromagnet and the material it is made of essentially does not retain magnetism. If at all, wouldn't the flux be from the stronger electromagnet?

Of course any magnetic flux from anywhere can over time cause problems, As Tim said, the record heads can be indeed affected as well, but here I'm talking mostly abot the playback heads, which in a typical 3-head configuration do not purposely impart any magnetic flux of their own (unlike the erase and record heads, which do.)

Also, there is the inverse square law to consider (for every doubling of the distance from the source of the field, the strength of the field is reduced four times). While there the flux from the adjecent heads can possibly cause problems, they still are not extremely strong, and are virtually infinitely farther away from the playback heads than the tape itself, which is actually physically touching the heads. I don't know the exact numbers and values, but it is at least theoretically possible that the amount of flux reaching the playback heads from the tape could actually be larger than from any adjecent heads (I could be wrong about that.)

Also add in the fact that the record and erase heads are only active when recording is in progress, but the tape is always there regardless of function, and the tape has much more opportunity to magnetically contaminate the playback heads.

And, as Tim said, demagging the heads should not be something that needs to be done all that frequently - at least certainly not as frequently as a good tape path cleaning - unless there is a defect or problem somewhere causing undue problems.

Just to add to that, it's very important to fiollow the demag process completely and correctly. A slipshod demag process can actually (in a wose case situation) make things worse and not better. It's not that the process is hard at all, it's just that it does require paying attention, being careful to do it right, an not just phoning it in.

G.

 

[NYMorningstar]

The effect is a bigger noise floor, and erasure especially of the highs. Sometimes you can hear bass like thumps coming through.
Tim

I hear what you are saying but without absent test results, I'm having a hard time going for it.

These symptoms I've seen associated with head wear, not magnetic interferance. When a head wears down, minor problems develop with a gradual deterioration in performance.

On metal heads, the symptoms are a result of minor changes in contour and tape-to-head contact loss caused by wear. These include: signal amplitude instability, slight loss of high frequency, and unstable tracking or tape path.

Ferrite record and playback heads, due to the extreme hardness and composition of the core material, do not wear as conventional metal heads do.
Slight losses in high frequency response are generally the early indications of core surface and gap deterioration caused by material erosion (head wear).

Everything I've ever read on this aside from the advertising for demagnetizers shows these problems developing from wear not residual flux buildup on a tape head.

Has anyone ever measured the flux buildup on a tape head?

 

[The Axis]

Lots of previous replies....but basically "yes", a lot of people have experimented with sending digital to tape and then back. The theory is that imparts a pleasant compression and frequency characteristics. I have heard of it off and on for at least 20 years.

If it sounds good to you, then it is good.

 

[Tim Gillett]

I hear what you are saying but without absent test results, I'm having a hard time going for it.

These symptoms I've seen associated with head wear, not magnetic interferance. When a head wears down, minor problems develop with a gradual deterioration in performance.

On metal heads, the symptoms are a result of minor changes in contour and tape-to-head contact loss caused by wear. These include: signal amplitude instability, slight loss of high frequency, and unstable tracking or tape path.

Ferrite record and playback heads, due to the extreme hardness and composition of the core material, do not wear as conventional metal heads do.
Slight losses in high frequency response are generally the early indications of core surface and gap deterioration caused by material erosion (head wear).

Everything I've ever read on this aside from the advertising for demagnetizers shows these problems developing from wear not residual flux buildup on a tape head.

Has anyone ever measured the flux buildup on a tape head?

Demagnetising tape heads and guides has been standard practice in the tape recording industry ever since it began. Nothing startling or new here.

Head wear causes the problems you mentioned. Magnetised tape path causes the problems I mentioned.
If you were taught only to demagnetize guides and rollers but not heads you were taught wrongly.

Cheers Tim

 

[NYMorningstar]

If you were taught only to demagnetize guides and rollers but not heads you were taught wrongly.

Cheers Tim

I understand your argument, I was just looking for proof. I have seen demagnetizers for cd players too but that doesn't make it a viable option.

 

[Tim Gillett]

I understand your argument, I was just looking for proof. I have seen demagnetizers for cd players too but that doesn't make it a viable option.

Reading through your posts, you seem to think that because a magnetic material, as in a tape head, is "soft" that it is infinitely soft.
But it's only a relative description. The head can still be magnetized, and retain that magnetism until something else comes along to demagnetize it.

Howard Tremaine in "Audio Cyclopedia" (rev.edn 1979) says "a magnetized recording head will decrease the signal to noise ratio 6 to 10 db. Also it will gradually erase the high frequencies during playback."

Cheers Tim

 

[NYMorningstar]

Just got back from a trip I've been trying to research this some more. I have come to the conclusion that it's much to complicated for me to grasp without taking on another career.

I don't mean infinitely soft, just of no consequence.

I still come across statements that say that there may or may not be residual buildup in the heads that cause a noticeable difference in playback. I just read an article from UCLA that says erase heads don't need demagnetizing. I have seen one that says record heads don't need it either because as soon as you turn it on it is a magnet again. The bias and gap do seem to have much more a contribution and the residual flux diminimus.

In your article stating "a magnetized recording head will decrease the signal to noise ratio 6 to 10 db. Also it will gradually erase the high frequencies during playback.", does it mean residual?

I still believe that demagnetizing the heads is unnecessary and if done incorrectly it will end up polarizing them. But still, to complicated for me. I'd sure like to see an engineer explain it in simpler terms.

 

[MCI2424]

Demagnetising tape heads and guides has been standard practice in the tape recording industry ever since it began. Nothing startling or new here.

Head wear causes the problems you mentioned. Magnetised tape path causes the problems I mentioned.
If you were taught only to demagnetize guides and rollers but not heads you were taught wrongly.

Cheers Tim

There are some funny things in history that recording engineers did simply because they were taught by their mentors to do it. The Beatles and crew broke and proved wrong so many "rules" that they turned Abbey Road Studios upside down.

They believed you cannot re-record over tape (all recordings done on virign tape)

You will destroy a mic by putting it too close to a loud source (Geoff Emerick put it *indside) the kick drum.

You can't roll the tape deck into the control room for fear of losing the alignment forever (how did they get it aligned upon delivery?)

You can't stack on over 1 pre-amp stage or you will blow up the console (Revolution used 4 stages!)

You must always clean and demag heads every session.

The cleaning is good, but demagging is overdone by studios in my opinion. It is done (like aligning) for every session for safety reasons, and I can certainly understand it, but I know some home recorders who have never demagged ever for years and their decks don't show any signs of being horribly magnatized.

Who really knows what the exact answer is?