CDV- 700 Loudspeaker
- Hi all- Happy New Year.
I've found a nice loudspeaker solution for CD V-700- it's small,
cheap, easy to make from common material,and is adequately loud for
most uses. It is built inside the stock headphone dust cap, so it
doesn't change '700 appearance. It can be easily removed, and
requires no mods, but one tiny hole in the dust cap does make it
work much better.
I posted pictures of these parts. You need a piezo sounder element
that can be trimmed to 14.75 mm dia. Most of the cheap, dime-sized
ones fit this discription- you may have to break away the plastic
sounder case. Do this carefully to preserve the front solder
You also need two rubber "O" rings that will friction fit inside the
dust cap of the headphone connector. (I used nitrile rings, size r-
09 from a Harbor Freight O ring assortment.) And a ball point pen
spring. Tools: wire cutters, needle nose pliers, soldering iron,
solder, some flux.
Trim the piezo disk to size. It should be small enough to exactly
fit inside the '700's headphone dust cap- try to avoid cutting the
active (white) part of the piezo. The element is thin brass, and
small scissors cut it easily. After you cut it, check the brass back
to make sure there is no insulating varnish. Sand it clean if
Next uncoil the end of ball point spring to make a whisker sticking
out about 5mm. Shape the spring so that when that whisker is
soldered to front side connection, the remainder of the spring is
centered on the sounder disk and sticking up. (To solder to the
steel spring wire, use some aggressive flux to 'tin' the whisker. I
used Zinc Chloride. Wash the spring in hot water to remove the
excess flux- it's corrosive.) Solder the tinned whisker to the front
solder connection on the piezo disk. Work quickly to avoid
overheating the element. Trim it to about 5mm high, and save the
remainder of the spring. Test your speaker by pressing wires to the
front and back of the element from the -700 headphone jack. You
should hear it clicking.
The remaining piece of the ball point spring must be carefully
shaped to serve as the back electrode connector, as well as
connector to the ground terminal of the headphone connector. See the
picture and drawing. Test fit this spring inside the dust cap to
make sure the center coil is centered in the cap, and aligned with
the axis of the cap. Be patient- this is a fiddly part. It doesn't
have to be beautiful. Overall height is about 7-8mm for the outer
wire, and maybe 5mm for the inner. It isn't critical.
Now assemble the parts in the dust cap. First, place the back
electrode spring. Then, the first O-ring, then the piezo element,
then the front O-ring. Work the outer wire from the back electrode
spring around so that it extends past the edge of the piezo disk and
the front O ring. It should tuck inside the dust cap's edge, and
contact the ground of the connector when the cap is mounted on it. .
Test. Press the dust cap onto the connector, turn up a test source
and listen. You should hear distinct, muffled clicking. If not, Test
the assembly with wire connections to a CDV-700 or other signal
source. Adjust the shape of the springs as needed.
Once working, you can make your speaker much louder with a small
hole in the dust cap, right next to the rivet. I used 3/32". The
ball chain's clip can be rotated to cover the hole, leaving the '700
looking totally original- but now it has a loudspeaker.
As always, comments and improvements are welcome.