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Old 24th May 2006, 07:03 AM   #11
Netlist is offline Netlist  Belgium
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Quote:
Originally posted by PMA
I had been working a lot with them in their times.
103NU71, 156NU70, OC71, OC30, OC26, 2NU74, GC511/GC521, GD607/617 and many others.
Care to dig in your archives and show us a glimpse of what you did with them?

/Hugo
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Old 24th May 2006, 09:24 AM   #12
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Quote:
Originally posted by Netlist


Care to dig in your archives and show us a glimpse of what you did with them?

/Hugo
I am sorry, it was done in the late sixties and early seventies of the last century. No PC drawings, and hand drawed artworks not archived yet. I know that I greatly appreciated when Si transistors appeared on the market, BC series, 2N3055 etc. I would not like to go back to Ge thermal instabilities, noise and ageing. Also, I do not think much about their sound, contrary to JC. Unfortunately I did not save any of those Ge amplifiers. I still have several Si amp boards from middle seventies, and to tell you frankly, their sound is very very poor compared to properly done up-to-date design.
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Old 24th May 2006, 09:39 AM   #13
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Thanks,
I remember a thread where the Telefunken Bajazzo was discussed and I believe it was John Curl who still had a few lying around.
I think I can find more schematics of Germanium designs in my archive.
I still have quite a few different types lying around.
If someone can start an interesting project with them I wouldn't mind to donate some. I'll make a list of what I have later.

/Hugo
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Old 24th May 2006, 11:27 AM   #14
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I have 6 pairs of AC128K/AC176K.
10 pairs AC187/AC188
8 X AD149
A bunch of AF's, HF Ge's.

I found some interesting schematics which I'll scan and post later.

/Hugo
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Old 24th May 2006, 12:16 PM   #15
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I listen to my HEA 2000 radio every day with pleasure - made in Austria in the early 70ies with Germanium transistors (AC187/188 output stage, etc.). Together with the oval inbuildt Celestion loudspeaker it beats every other kitchen radio I have heard hands down, the Tivoli#1 and other highprice items included. I had to change the elcaps yet, but none of the transistors (I must state the I have found this gem in a pile of junk...)
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Old 24th May 2006, 01:50 PM   #16
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Imadea 2+2 watts AC187/01 Ac188/01 amplifier...made in the early 80's...it was a kit ...
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Old 24th May 2006, 02:04 PM   #17
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Quote:
Originally posted by lohk
I listen to my HEA 2000 radio every day with pleasure - made in Austria in the early 70ies with Germanium transistors (AC187/188 output stage, etc.). Together with the oval inbuildt Celestion loudspeaker it beats every other kitchen radio I have heard hands down, the Tivoli#1 and other highprice items included. I had to change the elcaps yet, but none of the transistors (I must state the I have found this gem in a pile of junk...)

I believe this was in large part to the fact that at that time they understood how to design a well-tuned loudspeaker/enclosure system that gave good sound, including the suggestion of good bass, from even a fraction of a watt output power. That knowledge (and interest) seems to be forgotten later.


Interestingly, lately it seems that it is rediscovered and taken even further with the Bose waveradio and the Bose IPOD docking system, which, although not being HIFI as we understand it, do produce phenomenal sound including strong bass from a dinky package and low power.

What goes around, comes around.

BTW, I may still have a source for AC187/188 and AD161/162 if someone needs them. No idea about the cost but I can ask.

Jan Didden
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Old 25th May 2006, 11:19 AM   #18
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Jan,

maybe you are right, but this radio is merly a small wooden box, nothing really tuned or refined. It is surely not the merit of germanium transistors alone, that is definitely true. But I learned in the old days that the silicon ransistors are so much more reliable.

Naively asked: Is is possible that gemanium transistors (cause of the much lower pe transition of only 0.3V) may have lower crossover distortions (in classic AB biased push-pull circuits) than their younger cousins? I remember the first schematics I study with GE transistors were transformer based power amplifiers (phase shifting driver and output) with PNP GE power transistors (most GE transitors were PNP).

I recently found several classic GE transistors in my junkbox, and I will make a NAIM style preamp just to listen to the differences. In the old days transistors were very expensive, so active loads etc. were out of reach probably.
I am not a bit nostalgic but curious, maybe with todays knowledge old things can be looked at a different angle.
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Old 25th May 2006, 01:21 PM   #19
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I've scanned some old stuff which can be found here.
Enjoy.

/Hugo
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Old 25th May 2006, 01:41 PM   #20
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Anyone happens to have the schematic of Heathkit AA-21D which is using germanium xistors too..

Thanks
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