Germanium investigations

[joshvi]

3AD6 is germanium.
2SB337 is silicon.
I cannot find 3AK30

2SB337 is germanium

 

[Soundhappy]

Do you see what transistors on the photos ?

 

[joshvi]

Not clear, difficult to read from photos and may be with different transistors.

 

[astouffer]

What is everyone expecting from AliExpress? Not a bad price for a metal case with all the knobs and jacks included. As a bonus you'll get some electronics that may or may not function.

 

[OldDIY]

MULTIWATT TW40 Junior - amp 25w class B KU606(Si)+4NU74(Ge)
https://www.elektroakustika.cz/images/tesla/tw40/tw40_3.jpg

 

[adason]

aaah transiwatt!
brings back memories...I used to live in czechoslovakia and build a dozen of various transiwatt amplifiers, the most dreadful sound you can imagine

 

[Nelson Pass]

I dunno. I can imagine pretty dreadful...

 

[MEPER]

Does "dreadful" mean something positive in the context?

 

[adason]

highly class B positive for crossover distortion

you need migraine?

 

[MEPER]

Ok, but why that many transistors to make it sound that bad?
It is a funny choice to make it a class B?
Was it to save power? ....or just for "non-HiFi" use like systems for speech only or "background music"?

 

[chip_mk]

Not that many for phono stage, preamp with tone control and power amp. I had a radio with kindred electronic inside. Crossover distortion was clearly noticeable at low level listening. Perhaps not that bad due to natural leakiness and low Vbe of Ge output transistors compared to Si.

 

[adason]

What do you mean that many transistors? Its prety minimalistic in design.

Take the riaa preamp for instance. Its just two transistors with riaa feedback for fr correction. It cant get any simpler. Can you make it with just one transitor? I dont think so. It could use one more buffer on the output. I built many of these, they were noisy and sharp sounding, poor low fr response, poor overload margin.


Take next stage...line level stage with bass/treble. Its just two transistors, cant get any simpler. It starts with 1 megaohm volume pot, which makes it terribly noisy. And feedback from output should be buffered. Again, minimalistic, with quite poor parameters.

When it comes to output amp, i am no expert, but i believe the reason its done that way is TESLA that time was not able to produce complementary output transistors. This was only what they had to work with.

 

[chip_mk]

What do you mean that many transistors? Its prety minimalistic in design.

Precisely.

Ok, but why that many transistors to make it sound that bad?
It is a funny choice to make it a class B?

My point is it's not too many transistor having in mind it's complete feature rich integrated amp.

 

[adason]

Sorry, i have not seen your post, i was replying to Meper. Somehow my screen was not updated.

 

[MEPER]

It should not be that hard to apply a bit of bias to the output PP stage. My point was that why spend time on designing an amp that sound so bad if just a small adjustment like applying a bit of bias could make it a much better sounding amp.....if the amp was meant for playing music.

 

[MEPER]

By the way......I was told that TESLA made some fine tubes like ECC83/E83CC.....if it is the same company. I have considered to get a matched pair of TESLA E83CC for my 300B amp. The Germaniums are not for me...... 🙂

 

[Soundhappy]

Germanium line pre and headhone amp show on the scope GERMANIUM Single ended Class A Headphone Amp.
Very nice work 😀

 

[adason]

I have seen that thread, great work from Mooly.

I was cleaning my used stuff drawer, with boxes of old used transistors, and once i sorted stuff out, i found four output transistors, 2N3614. They measure as good.
Any idea what these are good for? I searched, but did not find much.

 

[Soundhappy]

Data sheet for expertise 1 Piece Motorola 2N3614 TRANSISTOR (R5S8.5) | eBay

 

[OldDIY]

2N3614. Any idea what these are good for? I searched, but did not find much.- Leak 30
#95
#105 in a 1960s SS amp Hohner Electra Piano