An unusual design.
A one-piece mold with corrugated half-roll
surround suppressing resonances. Paper-wound
voice coil former glued to the dome and this all
glued to a metal frame fitting into a wide magnet
gab. The frame holding the dome is made from iron
and it's major trouble removing the dome and even
worse getting it into place again without
damaging the voice coil. From one of the domes
here, Philips didn't get it right either and the
voice coil is scraping against the magnet gab.
View impedance profiles below.
The pole piece has a hole stuffed with a foam
plug and on the rear top of the dome a small
piece of foam - to further suppress resonances, I
guess. 13 kHz peak? Anyway, quite a lot on
engineering went into this dome and despite not
having a copper plated pole piece (symmetric
drive) it displays a flat impedance profile.
Further info from Nils-Åke:
Thanks for the nice vintage things you still keep
doing ones and a while! Slightly vintage nerdy as
I am (unfortunately... or maybe not...) I though
I´d share somethings about the Philips domes.
The one you remembered using many years ago with
the flat surface is (from all of them Ive
seen) numbered differently, 0140 T4 or 8,
not 0160. The 0160 exist in various types, some
with a lager black reflector spot in front of the
dome (I think 14 or 15mm if I remember correctly)
and some with smaller (around 10..?) and the
polepiece in some are slanted inwards, some
are flat and the amount of stuffing varies...
stuffing them harder usually lowers the
impendance peak a lot and clears up some of the
rubish some have around the peak
also.. it also changes the FR slightly and
Fs goes down. Room for experimentation there.
Some have a small amount of foam (that usually
disintegrates over the years) on the top of the
dome, right under the black "spot" on
the grille, some have not. Olle Mirsch also had
some specially made for his speakers with
different mods, some of those with diffusor
fronts. Those I think have the modified
polepieces and I think I tried putting a 0140
front on one of those with pretty nice result
many years ago... dont remember exactly what I
did with it though... the years go by... ;-/
should this tweeter be mounted? Probably not like this. A
major bump at 7.5 kHz due to the deep moat around the
looks better (red curve) and is probably how it was
intended. The version I had in one of my Seventies'
construction had a flat faceplate for proper flush
the two domes flush mounted and displaying a nice
response profile, steadily rising towards 17 kHz from
where we see a rapid decline.
Some disturbance at 13 kHz, most likely related to
improper damping of top and cavity of center polepiece.
Impedance of the two domes, one compromised by skewed
centering. Right: Step response from best dome.
test done at 0.25 m distance, normalised for 2.8 volts/1
Left: 2nd (blue) and 3rd (green) harmonics shown. Right:
20 dB scaling and 4th (yellow) and 5th (purple) harm.
These tweeters are doing remarkably well compared to any
modern dome. Read distortion test here.
CSD, 20 dB scaling mounted according to example A.
Right: CSD, 20 dB scaling mounted according to example C.
Minor trouble at 13 kHz, otherwise fairly clean.
same as above with 40 dB scaling.
AD 0160/T8 is a fairly sensitive tweeter, easily making
up to a 90-92 dB midrange and as can be seen here, used
with a SEAS midbass tuned to 95 dB.
The /T4 version would make 93-95 dB, I guess, having the
AD 0160/T8 is not an easy driver to model. Rendering a
reasonably flat response takes a minor equalising step.
Above a 3rd order filter @ 3 kHz.
for fun: The SEAS CA18RLY set up with the Philips AD
0160/T8 in a 2-way system.
I'd be surprised if this confirms our prejudice of
"the world's worst dome". It most likely