A few
notes and graphs on these two ribbons. Apart
from a possible 1 dB difference in sensitivity from 2-7
kHz, these drivers are very much interchangeable. Even a
small dip at 3.7 kHz, which is possibly derived from
baffle geometry, is shared by the drivers. Both drivers
are flat down to 1.5 kHz but I will not recommend going
lower than 2.5 kHz. Use 3rd or 4th order filters.
 
Left: Red = Aurum Cantus G2Si-I, blue =
Aurum Cantus G2Si-II, green = Fountek JP3 (original
ribbon). 10 uF capacitor connected in series with driver
during measurement.
Right: G2Si, driver I & II. Measurements with
crossover seen below.
Crossover used for measurements.
Fountek JP3
Available from here:
GM Sound Denmark.
GM
Sound - Produkt 2
Available from Madisound, US:
http://www.madisound.com/,
price is 81-89 US$/ea depending on faceplate +
postage.
Aurum Cantus:
Europe:
http://www.hifisound.de
Germany:
This driver is called Harwood UR2.0
(peel off the label on the box and you will see
"G2Si".
Price is 119 EUR/ea (2131 DKK/pair at my
doorstep)
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28-09-2005: Received this mail from Mark:
I was googling and found your article about
replacement ribbon in Fountek. I have built a lot of
ribbon speakers of different configurations. At the
moment, I am into building ribbon microphones. The
constructions of ribbon tweeters and microphones are
very similar. If you don't mind I have a few tips.
One of the biggest problems is to make a good corrugator.
I machined mine on a mill with indexing rotary table.
However, I found this device: http://www.dickblick.com/zz049/07/. It is
not very good as a corrugator for
microphones, where the foil is much thinner - I am
working with 0.6-1.5um thickinesses. Basically, it
just tears the foil. Another problem is a ribbon skewing.
That is, the clearance in mics between ribbon and
pole pieces is less 0.01", so the ribbon should
be PERFECTLY straight. However, with something like
thicknesses of 4um and up, this
corrugator should work just fine. Make sure to get a
metal one. The plastic is uneven in the middle. If you
want to experiment with foils thinner than 11um
household aluminium, look in older paper-in-oil
capacitors. The thinnest I was able to find was 3.5um
Illinois caps. The lower the voltage rating, the thinner
material. Usually, it is about 6 um. Just unroll the
thing, place on a clean glass, and clean with isopropyle
alcohol. Do it outdoors. I heard it is not a good idea to
breath odour from these babies.
Best regards, Mark
Thanks to Mark for the information.
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