Germanium phono . Who uses phonopreamp on germanium transistors ?

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Andreas - Thanks ! You have done a good job on this scheme !  Very interesting !

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The phono preamp circuit from the Saba Telewatt amplifier . They applied an emitter cascade at the input . The same was done in some broadcast preamps of the 60s .           

[bykowina]

The scheme of the Beslik phonocorrector with updated values in correction

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bykowina - Thank you for the addition in this topic. Now I am building a germanium phono-preamp according to the scheme of Sergey Toropov (with a passive RIAA circuit ) . I will write about the results in a couple of days . 

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Hello everyone !  Germanium phono-preamp with passive correction. Sergey Toropov 's scheme ( published by him on one of the forums ) . The drawing of the board is mine . I have made changes to the nominal values of some elements - to limit the range in the infra - low frequencies . The gain is about 40 dB ( at a frequency of 1 kHz ) . Correction according to the RIAA standard, a decrease in frequency response is made below the frequency of 20 Hz .... I have not yet made measurements of the noise level and harmonics. I checked only the correction (through the generator / anti-RIAA unit / oscilloscope ). And I checked the board in working with the turntable  . The sound is very good , although the noise of the circuit turned out to be somewhat more than that of my other germanium correctors . I will insert the board into the case , and I will keep it in my collection . In the diagram , the denominations that I changed are highlighted with a red frame . Transistors are installed P416A , P416B ( military transistors of the USSR ) with beta in the area of 45-60 .

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30-volt power supply.

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Hi! Another germanium phono . I started assembling the preamp according to the Fisher TR-1 scheme.

[macuser]

Hello,

just found this article in Radio Mentor. It is from Elac and describes their PV 2 single stage preamplifier:



Kind regards
Max

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Phono preamp is ready for testing .

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The first tests of the FISHER TR-1 corrector board were quite successful. I had to make small changes to the scheme - to improve the transient characteristics of the corrector when measuring on a meander . I applied 22 volts of power ( but I also checked the operation from 13 volts , as it was in the original scheme ) ... I also reduced the maximum gain of the circuit to 42 db / 1 kHz - in its original form it was about 48 dB, but I don't need that much.... The corrector sounds good, the frequency response closely corresponds to the RIAA (checked through anti-RIAA). And at frequencies below 30 Hz it has a smooth gain drop ( at a frequency of 10 Hz - a cut of about 6 db - compared to a frequency of 30 Hz) .... I have used P-416 with a small beta (about 30 ). There are no more transistors with a larger beta so that you can pick up pairs in the channels . I'll buy more transistors - I'll replace them with copies with a larger beta .... But it plays so well. The current consumption ( when powered by 22 volts ) is about 3 milliamps per channel . I will install the board in the case ...The scheme is now like this .

[gibber]

Interesting, i‘m tempted to try Germanium and tried to find ACY32. Given that the input T‘s beta is perhaps the biggest headache, that could be silicon. Is your regulator T1 (after the 337) a Germanium type?

W: is the fifth of the larger ‘lytics on the PSU part of the board mounted from below or is it supposed to be near tranny and rectifiers?

— Ralph

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Interesting, i‘m tempted to try Germanium and tried to find ACY32. Given that the input T‘s beta is perhaps the biggest headache, that could be silicon. Is your regulator T1 (after the 337) a Germanium type?

W: is the fifth of the larger ‘lytics on the PSU part of the board mounted from below or is it supposed to be near tranny and rectifiers?

— Ralph

Transistor T1 in the power supply is germanium GT403 ( manufactured in the USSR ) , but of course you can use any silicon with a collector current of 100-200 milliamps ( or more ) - bc-560 and others.

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W: is the fifth of the larger ‘lytics on the PSU part of the board mounted from below or is it supposed to be near tranny and rectifiers?

— Ralph

A few words about the power supply . Capacity 1000 mkf - consists of 2 capacitors of 470 mkf  each. So I did because of the dimensions in height (the case for this phono-preamp has a small height) . Output capacitors of 220 mkf are installed in the phono-preamp channels ( next to the green terminals) . Transformer and rectifier are installed in a separate case . I always do that . A rectifier on fast diodes and a filter capacitor of 3300 mkf  .

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The germanium transistors P-416 ( П-416 ) that I used are high - frequency transistors ( frequency band - tens of megahertz ) . But they also work well in audio devices. They have small leakage currents - much less than those of AC-122/125/ 151 transistors. The original FISHER TR-1 circuit used 2N109 transistors, but I didn't even try to find them.

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The phono preamp board according to the Fisher TR-1 scheme is installed in a metal box.