On Oct 29, 8:33 am, "N Cook" wrote:
Ideally identifying which and dismissing the roady would make more sense for
this locally based, but made big-time band.
Failing that - concerning cut grommets encircling valves to act as retainers
in inverted amps. Lining the holes in the chassis where the valves pass
through .
a/ fairly rigid rubber of otherwise standard trunking grommets
b/ fairly tight to the glass envelopes to function as retainers.
c/ obviously they do no take much a jarr to cause breakage as no obvious
damage to the cab.

The 4 o/p valves have spring retainers.
One of the ECC83 quite neatly split in a ring where the grommet lies and
white cap.
I am thinking of running my plaited, high temperature silicone cord "rope",
over the tops of all 6 of these small valves , located over the top "pips"
and anchored to the chasis at the ends.
Any comments pro or con ?

I think the problem is not retention of the miniature tubes, but the
fact that their socket (some distance under the chassis) obviously was
jarred and shifted/vibrated enough to cause the tube envelope to hit
the chassis hole.

I think that enlarging the hole or stiffening the chassis is your only
choice. Retainers keep tubes in their sockets, but do not stop the
socket from moving under the hole.

Tim.