Hello, Gregorio,

In general, the magnetic record seems to be rather robust and it mostly 
decays from close encounters with magnetic fields stronger than the 
Earth's. I know of no studies that have attempted to quantify this, but 
I'm copying Jay McKnight who may know of a study and if he has any 
information, I'll post it to the list.

So, assuming no chemical or physical degradation (which mostly affect 
tape via spacing loss across part or all of the tape) and no close 
encounters of the strong magnetic kind, the S/N decay rate would be 
minimal (I don't want to say zero, but I suspect close to it).

We had the discussion on the Studer list about whether tape or machine 
background noise is predominant and Jay chimed in with an "it depends". 
For master tapes, generally the tape noise is predominant. There are 
times at slower speeds and narrower tracks where head/electronics noise 
would be predominant.

As to degradation factors, I have a page I try and keep updated where 
this is discussed.

I hope this helps a bit.



On 2013-04-17 12:32 PM, Gregorio Garcia Karman wrote:
> Dear members,
> I am looking for references in the literature dealing with the study of the decay of magnetic remanence as an effect of tape aging. What is the expected signal-to-noise decay rate under ideal conditions (i.e. no chemical degradation)? In real life, what is your experience in regard to different brands / models in similar storage conditions?
> Thanks in advance and regards
> Gregorio

Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
Quality tape transfers -- even from hard-to-play tapes.