136HS stripped naked

[subwoof]

Bet this one shows up in a lot of searches..

Well it's time to dissect the rare 136HS and see just how it is made.
This unique sub is used in the consumer synthesis line and probably in
many of those wonderful Japanese models that WE CAN'T GET in the US.

First a couple of things about the ferrite 4" coil motors from JBL. For
convenience sake we will NOT include the 2215/LE15/145 types nor alnico
comparisons. These observations are not definitive but based on hundreds
of baskets that have gone thru my fingers in the last 30+ years.

(1) There are 2 depths of gaps: The thinner (5/16) includes the majority
of motors like the 2225, E120/30/40 and consumer 124/135/136. The
deeper gap ( appox 3/8) is reserved for the 2220 and 2245.

(2) There are 2 thicknesses of actual ferrite slugs: 3/4 and 7/8. Again
the thinner includes the majority like the 2225, 2220 and consumer
124/135/136. The thicker is used on the musical series ( E120/130/140 )
and the 2245.

(3) There are a myriad of coils, spiders, lead wires and dust caps so we
will only refer to them if/as needed.

(4) There are *probably* different back caps for the motors but no
literature outside JBL engineering is available so educated guesses have
to be made. Same for the "shorting ring" that is used at the base of the pole piece.

So after receiving a pair of baskets ( thanks alan! ), And patiently
waiting for a breezy non-rainy day outside to unglue a kit from a frame,
here's what I found.

(A) The voice coil assembly belongs to a 2245H !! And therefore requires
the deeper gap to work correctly.

(B) The paper and cloth surround are the current 3 roll types used on
the pro series 2226H and many others.

(C) The spider is as STIFF as the 2226 also. NOT the extra-flexible ones
found on the foam surround types. However this is a difficult thing to
actually measure.

(D) The lead wires are copper - not aluminum. it's possible this has
been changed since the build date is at the changeover era ( mid 1991 ).

(E) The back of the cone is aquaplassed and there is NO mass ring.

(F) The frame is the standard 15" ferrite model, the magnet thickness is
3/4 and the gap is the deeper one SO the motor is the 2220H without the
mass ring glued on the back.

NOT THE 2225 and NOT the 2245 !

So it looks like a way has been found to reuse the orphan 2220H that
seems to take over shelves and shops....by reconing them with this kit
you get:

(I) DOUBLE the power handling ( 600w ) With this caveat: The xmas will
be different due to the overall *depth* of the motor assembly countered by the
*lack* of a mass ring.

(II) Look ma - no foam.

(III) No more annoying "tink tink" when slamming 2235H ( with mass
ring ) backwards onto the pole piece.

(IV) The hassle of going through JBL consumer to get the part. Service
centers know how FUN that is....not...

sub


ref:
motor means the actual magnet assembly.
frame means the aluminum part that the motor mounts to.
basket is the above paired together.
cone assembly includes the surround, spider, paper + cap, wires and
voice coil/former.

[4313B]

(III) No more annoying "tink tink" when slamming 2235H ( with mass ring ) backwards onto the pole piece.

Note that the bottom of the mass ring is on the same plane as the spider so when the mass ring smacks the pole piece the spider is smacking the top plate.

The mass ring has really fallen out of favor. Current thinking is to just use the 2234H and EQ it.

(C) The spider is as STIFF as the 2226 also.

Too stiff.

But JBL wanted to prevent bottoming out as much as possible.

So it looks like a way has been found to reuse the orphan 2220H that seems to take over shelves and shops....

Thanks for the info. Very nice!

[Triumph Don]

IMO Mass rings are just bad.