1 inch speaker problem

[N_Cook]

Nastly little magnetic tweeter/mids ?
As a 47uF NP cap is over one, for mid?
Anyway nasty buzzing overtone as though a bit of steel swarf or staple
has got on the cone of a larger speaker.
These things have brushed aluminium inverse dome covers on them, do they
work loose, swarf dislodged inside?
Of course close-handling has "cured" the problem, but bound to return
without proper treatment

 

[Gareth Magennis]

"N_Cook" wrote in message news:n7la85$b2u$1@dont-email.me...

Nastly little magnetic tweeter/mids ?
As a 47uF NP cap is over one, for mid?
Anyway nasty buzzing overtone as though a bit of steel swarf or staple
has got on the cone of a larger speaker.
These things have brushed aluminium inverse dome covers on them, do they
work loose, swarf dislodged inside?
Of course close-handling has "cured" the problem, but bound to return
without proper treatment






I take it you mean a shit hi-fi speaker with a one inch voice coil.

Have you checked it's not a Surround problem? i.e. the attachment to the
outer rim of the chassis has failed.
Or sometimes the dustcap itself comes loose and rattles.
Or sometimes the bottom spider suspension becomes detached from the inner
part of the chassis.



But mostly its because the owner has blown it, and there are burnt or loose
pieces of voicecoil rubbing intermittently.


You might also check that the magnet hasn't become partially detached from
the chassis.
That's a good one for a pub story.



All the above much more likely than an otherwise foreign body entering the
gap.
In my experience.




Gareth.

 

[Gareth Magennis]

"N_Cook" wrote in message news:n7la85$b2u$1@dont-email.me...

Nastly little magnetic tweeter/mids ?
As a 47uF NP cap is over one, for mid?
Anyway nasty buzzing overtone as though a bit of steel swarf or staple
has got on the cone of a larger speaker.
These things have brushed aluminium inverse dome covers on them, do they
work loose, swarf dislodged inside?
Of course close-handling has "cured" the problem, but bound to return
without proper treatment




You also might want to remount said speaker with that recommended to tighten
cylinder head bolts, so it's flimsy chassis does not warp in the process.

Though I would guess you are very aware of this method already.

https://www.google.co.uk/search?q=cylinder+head+tightening+sequence&ie=utf-8&oe=utf-8&gws_rd=cr&ei=58KeVoeKKobbU8r1oIgO



Gareth.

 

[N_Cook]

On 19/01/2016 20:54, Gareth Magennis wrote:

"N_Cook" wrote in message news:n7la85$b2u$1@dont-email.me...

Nastly little magnetic tweeter/mids ?
As a 47uF NP cap is over one, for mid?
Anyway nasty buzzing overtone as though a bit of steel swarf or staple
has got on the cone of a larger speaker.
These things have brushed aluminium inverse dome covers on them, do they
work loose, swarf dislodged inside?
Of course close-handling has "cured" the problem, but bound to return
without proper treatment






I take it you mean a shit hi-fi speaker with a one inch voice coil.

Have you checked it's not a Surround problem? i.e. the attachment to
the outer rim of the chassis has failed.
Or sometimes the dustcap itself comes loose and rattles.
Or sometimes the bottom spider suspension becomes detached from the
inner part of the chassis.



But mostly its because the owner has blown it, and there are burnt or
loose pieces of voicecoil rubbing intermittently.


You might also check that the magnet hasn't become partially detached
from the chassis.
That's a good one for a pub story.



All the above much more likely than an otherwise foreign body entering
the gap.
In my experience.




Gareth.

So far, 3 pages worth of images, I've not found any replacement ones
available anywhere, 4ohm, presumably about 3W, actually 30mm not 1 inch
diameter. So I'll unglue them and see what I can see

 

[N_Cook]

First time I've been hands on these sorts of speakers. Tinsel wire
pigtails are more circumferential rather than large speaker more
axial/radial but evenly spaced so unlikely knocking against VC or
surround, but I may decide on a dab of lacquer on those in case they are
resonating in use and then touching, well hardly hifi speakers anyway.
26mm diameter metal part 31mm diameter plastic surround for the
suspension and onward fixing. The glue may have softnened holding hte
plastic surround into the body of the donut as very easy to remove, so
hotmelt will go in there on replacement. Also one of the little crimp
shoes came off very easily. I'll swap over the "mid" and "treble" ones,
both 4R in series , so 8R to the amp , but 47uF over one of them. Amp is
little fine pitched leadout flip chip for 4R bass speaker and 2x2 of
these little speakers, bolted to a little vaned heatsink
There is no slot in the magnet, just a cup it seems, so unlikely the VC
is rubbing on anything and seems good bond to the cone/dome sounder
section.
Suspension looks good.
I'll give a blast through with 1KW Martindale blower , hopefully
dislodge any swarf inside the magnet cup and hope they survive that as
still no like for like replacements found.

 

[N_Cook]

I've decided it is pigtail problem. Looks as though they've taken up an
unpowered position too close to the periphery plastic. Bent them all
away from it and added a dot of lacquer on the terminal end of each
pigtail, hopefully stopping the tails setting themselves back again.