germanium Preamp?

[vsmusic]

I am surprised to read these low noise levels achieved with Ge-transistors. Like KayPirinha my experience with the Ge-types available to me at this time like OC70, OC71, AC122,GFT32, OC304 etc were quite noisy compared to the upcoming Si-BC109.

The noise of a germanium Phono preamp is much less than that of a pure LP groove

 

[Kay Pirinha]

I am surprised to read these low noise levels achieved with Ge-transistors. Like KayPirinha my experience with the Ge-types available to me at this time like OC70, OC71, AC122,GFT32, OC304 etc were quite noisy compared to the upcoming Si-BC109.

Yes, especially the AC122, as used by vsmusic, wasn't exactly known for low noise.
There were better Germaniums in terms of noise, btw, the AC150 for instance.
Best regards!

 

[Kay Pirinha]

The noise of a germanium Phono preamp is much less than that of a pure LP groove

Agreed. But I expect a phono preamp to be almost noiseless especially if the tonearm is lifted.
Best regards!

 

[vsmusic]

Agreed. But I expect a phono preamp to be almost noiseless especially if the tonearm is lifted.
Best regards!

: ))))) ...Then listen to the silicon preamp . And I will continue to use germanium - I have 2 of them ( probably there will be more )

 

[vsmusic]

Yes, especially the AC122, as used by vsmusic, wasn't exactly known for low noise.
There were better Germaniums in terms of noise, btw, the AC150 for instance.
Best regards!

The noise level of this preamp (with AC-122 transistors) is less than minus 70 dB . I took measurements using RMAA . This parameter is quite enough for me . I use vintage players ( pioneer and Kenwood), vintage Empire cartridges ...Why not a vintage preamp ?

 

[Kay Pirinha]

I use vintage players ( pioneer and Kenwood), vintage Empire cartridges ...Why not a vintage preamp ? View attachment 853317

Of course! I'm also on vintage gear (Dual and Thorens TT's from the 1970ies and 1980ies, Shure, ELAC and AKG catridges, tonewheel Hammond organs, airhead BMW's, steam locomotives…).
Best regards!
Edit: Your builds look phantastic !

 

[analog_sa]

Agreed. But I expect a phono preamp to be almost noiseless especially if the tonearm is lifted.

Not sure why is it so important what happens when music isn't playing and the volume is all the way up

If the sound is so much better with Ge, the noise issue can easily be overcome by paralleling.

 

[vsmusic]

For me, experiments with assembly on germanium transistors are very interesting . I had different preamps, including on FET transistors . But when I first collected and listened to the germanium preamp, I was surprised by its sound .

 

[Kay Pirinha]

If the sound is so much better with Ge...

...which still has to be proven…

...the noise issue can easily be overcome by paralleling.

Never noticed any design using paralleled Ge devices, most probably due to their enormous manufacturing tolerances. You'd have to carefully select form a big lot of specimen that aren't in production since a long time.
But agreed: That Shure M-61 offers astonishing data, especially for a Ge powered phono amplifier. Which devices are used in here?
Best regards!

 

[vsmusic]

...which still has to be proven…
Never noticed any design using paralleled Ge devices, most probably due to their enormous manufacturing tolerances. You'd have to carefully select form a big lot of specimen that aren't in production since a long time.
But agreed: That Shure M-61 offers astonishing data, especially for a Ge powered phono amplifier. Which devices are used in here?
Best regards!

The SHURE product used American transistors . But the phono scheme itself was the same as that of Telefunken TV-206 . I don't have transistors like SHURE used . So I can't compare them to AC-122 transistors . Telefunken used AC-122 transistors .I made a device like Telefunken's , using AC-122 . Power supply-32 volts . And this has been working for me for about 5 years

 

[Kay Pirinha]

If you can get your hands on AC150's, try to replace the first stage AC122's by them and report, please!
Best regards!

 

[vsmusic]

If you can get your hands on AC150's, try to replace the first stage AC122's by them and report, please!
Best regards!

I don't have the AC-150 yet either . I made the same device using the P-28 (USSR). These are low-noise transistors . The result was similar to the AC-122 transistors

 

[Kay Pirinha]

Yes, I know, chances to get AC150's aren't exactly big…
I've seen them in just one device so far, the GRUNDIG RT 50 AM/FM Radio.
Best regards!

 

[vsmusic]

AC-122 - low noise transistors . View attachment AC122.pdf

 

[U230421]

@ vsmusic:
Are there circuit drawings available of your low noise Ge-preamps?

 

[vsmusic]

@ vsmusic:
Are there circuit drawings available of your low noise Ge-preamps?

The basis of this scheme is Telefunken TV-206 . I've upgraded the basic scheme a bit . The changed values of the correction ( in TV-206 applied correction Teldec ) . And added a single transistor stage . Diagram of the Phono preamp and its power supply

 

[vsmusic]

The original scheme of TV-206 .

 

[Mark Tillotson]

Impressive draughting skills there - using a stencil? Took me a while to convince myself it wasn't computer generated!

 

[Kay Pirinha]

AC-122 - low noise transistors . View attachment 853335

Thanks! And now compare with AC150 ;-) : https://www.web-bcs.com/pdf/Tf/AC/AC150.pdf
Best regards!

 

[vsmusic]

Impressive draughting skills there - using a stencil? Took me a while to convince myself it wasn't computer generated!

Yes - using a stencil . When I make a device, I always use a drawing on paper ... Bad habit