RB Annis makes a magnetometer that measures the gauss rang of your heads.

http://www.rbannis.com/products/magnets.html

Also, I think if you are putting 6-8 hours a day on your machines,
demagnetizing them every morning is a good practice.  Hope this helps.

Justin Lemons


On Fri, Nov 1, 2013 at 2:55 PM, John Schroth <[log in to unmask]>wrote:

> As standard practice, I usually demagnetize the heads on any tape deck at
> the start of each morning when I'm doing audiotape digitizing. But it
> occurred to me that it might be worth asking what others on the list do.
> How often do you demagnetize your heads if you're putting 6-8 hours on them
> a day? Do you demagnetize more or less often for different formats (such as
> cassette verses reel-to-reel)? Is there a measurement device that could
> tell you if your heads require demagnetization?
>
> Any input would be appreciated.
>
> Regards,
>
> John Schroth
>