Electro Voice Sx 300 speaker

[N_Cook]

Bass driver giving off a noise like frying bacon of fairly constant level
compared to varying audio level. They had used epoxy glue and soft contact
glue at 2 different stages of fixing the spider to the frame. Epoxy had
squeeged into the interior forming beads of solid epoxy up to about 10 mm
long by about 2mm that had later broken off and was rattling inside. So
gummy/soft glues only is the lesson . As there is always bits of sub-mm
aluminium oxide etc , but greater than air filter mesh size , inside
speakers, that don't seem to make any humanly observed rattling
interference noises , anyone any idea what is the size that becomes
intrusive ?. In the core that is , not staples etc on the outside. RoHS
stickers all over and all sorts of other problems in the cab but not PbF
isssues (this year)

 

[Meat Plow]

Bass driver giving off a noise like frying bacon of fairly constant
level compared to varying audio level. They had used epoxy glue and soft
contact glue at 2 different stages of fixing the spider to the frame.
Epoxy had squeeged into the interior forming beads of solid epoxy up to
about 10 mm long by about 2mm that had later broken off and was rattling
inside. So gummy/soft glues only is the lesson . As there is always bits
of sub-mm aluminium oxide etc , but greater than air filter mesh size ,
inside speakers, that don't seem to make any humanly observed rattling
interference noises , anyone any idea what is the size that becomes
intrusive ?. In the core that is , not staples etc on the outside. RoHS
stickers all over and all sorts of other problems in the cab but not PbF
isssues (this year)

You want to know the size of a particle that could cause a rub between
the VC and the magnet structure core? Is so I can't imagine it would take
much knowing the tolerances around the VC are measured in the tens of
thousands of an inch. I've seen several of these type and guitar types
get re coned living near an individual who did re-coning for a living.
Some of the shims used while gluing especially in a studio monitor
speaker like a Tannoy I saw get re-coned looked to be around 1.5 mil or
slighlty more.

 

[N_Cook]

You want to know the size of a particle that could cause a rub between
the VC and the magnet structure core? Is so I can't imagine it would take
much knowing the tolerances around the VC are measured in the tens of
thousands of an inch. I've seen several of these type and guitar types
get re coned living near an individual who did re-coning for a living.
Some of the shims used while gluing especially in a studio monitor
speaker like a Tannoy I saw get re-coned looked to be around 1.5 mil or
slighlty more.

These bits were rattling around in the interior space not passing through
the air filter gauze or getting graunched in the vc gap. Demounted spicer
and cone and for "reconing" this one I used 3 slivers of credit card, hardly
thou/mil sorts of dimensions.

 

[Meat Plow]

These bits were rattling around in the interior space not passing
through the air filter gauze or getting graunched in the vc gap.
Demounted spicer and cone and for "reconing" this one I used 3 slivers
of credit card, hardly thou/mil sorts of dimensions.

I guess it's up to the person doing the re-coning as to what tolerances
they prefer.

 

[N_Cook]

I guess it's up to the person doing the re-coning as to what tolerances
they prefer.

You need a jam fit, to coin a term. Not a clearance or sliding fit as you
need the cone to stay at a pushed in distance, say 5mm below natural level.
To allow the glue to have a closing pressure that is a once only application
of force. Not removing hands and then placing a weight inside the cone. So
the circular VC former goes slightly triangular with 3 credit card slivers
or slightly squared with 4 (excessive deformation/ holding force for this
one)

 

[N_Cook]

I guess it's up to the person doing the re-coning as to what tolerances
they prefer.

The precision required for a shim cylinder (even with an axial gap) for
coning/reconing would be near impossible to have a "jam fit"

This one given a work out with high power 50 hz and now back with the owner.
Does not bode well with its fellow, 5 problems with this one. Loose horn,
loose spade connector, another one the wire came out of the "crimp" on
normal handling, spider of the bass unit partially unglued from basket and
these bits of black epoxy rattling around inside (now in my black museum)