On 12/20/18 3:39 PM, Richard L. Hess wrote:
> I am going out on a limb here and say, in certain circumstances, I
> remove all non-essential, non-rotating components from the tape path.
>
> While the others' arguments are compelling, I'd like to suggest an
> alternate perspective. As we're dealing with tapes that often show an
> increased coefficient of friction, I see it as meaningful that we
> should remove as many as possible sources for stick-slip to occur in
> the tape path. The wrap angles often do not change dramatically with
> the removal of other heads.
If the single remaining head is mounted in the usual repro position,
just downstream of a scrape flutter idler, the wrap angle on the head
will not change. But... the sideways force on the scrape flutter idler
will increase, thus reducing bearing life and increasing bearing noise.
Bearing noise from a scrape flutter idler which is even slightly worn is
*very* sensitive to the amount of sideways force.
Speaking of scrape flutter idlers, Ampex's recommendation for cleaning
and lubrication was once a year or after 2,000 hours of operation -- a
recommendation which seems to be widely ignored. I've seen idlers with
badly worn bearing surfaces where the bearing noise was almost as bad
as scrape flutter.
I have headblocks which contain multiple repro heads, with only one in
use at a time. I cover the unused ones with Teflon adhesive tape, which
prevents wear on the head and greatly reduces friction. However, the
Teflon needs to be quite thin so that it does not significantly disturb
wrap on adjacent heads, so it must be replaced about every 20 hours.
-- John Chester
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