Serendipity strikes again. On July 28, 2001 I received the message below and photo/plot
from Mr. Dahlberg. Previously, his friend Lief Aden had advised me of the
Japanese "Ulfa" brand rotary knife for cutting aluminum foil for ribbons. Bengt
has a beautiful planar-ribbon combination loudspeaker.
"Hello Mr Whittaker. My name is Bengt Dahlberg (a friend of Leif Aden's). We have constructed a pair of fullrange planar/ribbons and when I saw the pictures that Leif sent you I just had to send you these ones."
"The speaker is standing in my livingroom, and the lspcad screendump is the frequency-response for the tweeter section taken from a 2 meter distance. Crossovered at 400hz second order and I'm only using one notch filter."
"Constructing the filter was an interesting experience because all filters seemed to sound good. So going from a first order with three notch filters to a second order with just one took some effort. I have also lowered the crossover from the first one at somewhere around 800hz to somewhere around 400hz (electrical at 320).Hope you'll enjoy the pictures." Bengt from Umea Sweden.
Bengt can be reached at: d.bengt@bredband.net
Bengt has supplied a photo of the back of one of his ribbons. This is what I'm calling a
'quasi-ribbon' in that it uses multiple conductors on a film backing. The yellow color of
the film is indicative of Kapton (TM) - and the corrugation or pleating is absolutely
professional in appearance. He indicates that the ribbon is 26.5mm in width in pole gap of
29mm (ribbon-to-pole face tolerance of 1.25mm per side).
Hans Struwe of Denmark pretty much saved my life back in December 1999. Trying to cut aluminum foil on my new cutting bench by taping it down was driving me crazy. He wrote me out-of-the-blue, and advised that water could be used as 'glue' to adhere the foil to the cutting mat. This method works well indeed, and allowed me to get a couple ribbons cut and get my 1cm x 182.5cm true ribbons playing in January 2000. I have promised to always refer to the "Struwe Wet-Processed Ribbons" that I will make using this method.
At the beginning of August 2001, Hans wrote, "I am still using the same ribbons, the only change has been on the woofer side, swapping to Scan Speak W8545. The sound is very good, I really enjoy playing the system. Changing the CD and amplifiers has demonstrated a huge potential in the speakers."
"I have tried no. of high end speakers and compared them to my ribbons, but no one get's near the soundstage provided by the ribbons. I have become true ribbon addict."
Hans has built an interesting suspended ribbon module above a woofer module. The multi-conductor ribbon element appears to show some very deep corrugations.
Hans write that he has recently started his own company as a independent AV-consultant, and that business is going well. All the best Hans!
Hans can be reached at: hans.mie@mail.dk
Acoustic Line Source Research - Table of Contents.
