We discussed Jan Lohstroh here, who actually designed and build what came to be known as 'the Otala amp'.
I interviewed Dr Lohstroh, and this interview can be read here:
http://www.audioamateurinc.com/digital/609/pageflip.html
The article starts at page 5: "An afternoon with Jan Lohstroh". He also comments on the PIM/IMD discussion.
There's a link at the very end of the article on page 9 that gets you to a short video with Lohstroh playing the Steinway.
Edit: here's a link to the article itself: Lohstroh interview
jd
I interviewed Dr Lohstroh, and this interview can be read here:
http://www.audioamateurinc.com/digital/609/pageflip.html
The article starts at page 5: "An afternoon with Jan Lohstroh". He also comments on the PIM/IMD discussion.
There's a link at the very end of the article on page 9 that gets you to a short video with Lohstroh playing the Steinway.
Edit: here's a link to the article itself: Lohstroh interview
jd
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Thank you. I also put a link to the video with Lohstroh on the top of my website Jan Didden audio diy and other human frailties place , courtesy of Audio Amateur Inc.
jd
Jan do you know if the layout for the original design or any of the production designs is available?
Anyone?
Pete,
From what I've seen of the original prototype at Lohstroh's place, there was no layout - it was p2p wiring and a few of those ceramic solder tag sets you also find in test equipment of that time.
I guess that the Elektrocompagniet version would have a PCB but I don't know anything about that.
Why you ask?
jd
Just toying with the idea of building a copy - as close as possible.
Maybe when I retire, lol.
Also interested in BD203/204 data sheets from Phillips.
Maybe when I retire, lol.
Also interested in BD203/204 data sheets from Phillips.
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Not easy to find, those Electrocompaniet amps schematics.
Fortunately, Tiefbassuebertr has posted many by there...
Fortunately, Tiefbassuebertr has posted many by there...
This was an interesting and informative thread. Fun to see so many around the world still appreciate this historic little gem of a hifi amplifier. I even have a 25w 'ottala-amp ", produced in 1977. The special thing about my version is that it has "Electrocompaniet" as a trademark on the front plate, not "otal Lohstroh" or "The 2 channel audio power amplifier", which is most common. According entrepreneur behind Electrocompaniet, Per Abrahamsen, this is one of about eight amps that had this face plate, which was a sort of prototype. Abrahamsen confirms that these eight amps were the first who had Elektrocompaniet trademark on the front. This is probably the only specimen in Europe. The funny thing is that Per Abrahamsen, who has now gone out of Electrocompaniet, and has a company called Abrahamsen Audio has just released a new version of "The 2 channel audio power amplifier."
http://audiofidelity.no/comlete_mags/18.pdf
You who have technical questions about these amps, and need advice on repair, please send an email to Terry Sand Power, who was involved in the development of these amps. Terje.Sandstrom@inmeta.com
This is my ottala-amp.
http://audiofidelity.no/comlete_mags/18.pdf
You who have technical questions about these amps, and need advice on repair, please send an email to Terry Sand Power, who was involved in the development of these amps. Terje.Sandstrom@inmeta.com
This is my ottala-amp.
the late William Marshal Leach and his low tim amps are surely inspired by Matti Otalla...
his amps are the most diy'ed amplifier in the whole wide world...it's free.....
Nelson Pass is also coming out to give diy'ers his designs for free, exciting times...
his amps are the most diy'ed amplifier in the whole wide world...it's free.....
Nelson Pass is also coming out to give diy'ers his designs for free, exciting times...
Dr Leach memories
Dr Leach referenced Otala’s work in his articles. They both published in the Journal of the Audio Engineering Society. I was fortunate to have Dr Leach as my Prof in several classes, including some audio classes. He was a great Prof, really cared about his students, and provided the information to allow us to build some of his designs. The Leach amp that I built was special. Years after graduating, when I was working on another speaker project, he was kind enough to have a copy of his new audio book printed and shipped to me.
Dr Leach referenced Otala’s work in his articles. They both published in the Journal of the Audio Engineering Society. I was fortunate to have Dr Leach as my Prof in several classes, including some audio classes. He was a great Prof, really cared about his students, and provided the information to allow us to build some of his designs. The Leach amp that I built was special. Years after graduating, when I was working on another speaker project, he was kind enough to have a copy of his new audio book printed and shipped to me.
Regrettably, Otala's "work" was a masterly exercise in obscurantism and obfuscation. It served no useful purpose at all.