Thanks !
... In the next few days (maybe one week), I will show you the finished product and tell you more about it ...The first test was successful . And the sound was good . So I want to make it more thorough .
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Germanium phono preamp with battery supply .
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hello,
Some schematics: https://www.google.fr/url?sa=t&rct=...d=1283640111&usg=AOvVaw15c_PhU8zNt7uHnLKqbEA6
Some schematics: https://www.google.fr/url?sa=t&rct=...d=1283640111&usg=AOvVaw15c_PhU8zNt7uHnLKqbEA6
In 1972, I was at school . The RRR radio factory in Riga produced the Victoria 001 Radiola . It was a good Radiola . And very not cheap . It had a germanium transistor Phono amplifier . I decided to make a Phono preamp according to that scheme . I developed the printed circuit Board anew . I changed the scheme a little . Used transistors AC-122, Gt308v, MP-37B . Power - 2x12v batteries ( 0.8 A / h). The arrow indicator shows the battery level and the signal level in 2 channels . You can switch off the display and backlight of the indicator - this saves battery life . The sound is very good . The circuit has a rumble filter , and it is very effective at frequencies below 20 Hz .
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Several photos of Assembly work ....
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Specification. Resistors .
R1- 51k ( 75k ) …R2 - 220 …R3 - 56k …R4 - 6,8k …R5 - 270k
R6 - 36k…R7 - 820…R8 - 20k…R9 - 200k…R10 - 8,2k…R11 - 8,2k
R12 - 1,5k…R13 - 6,8k…R14 - 10k…R15 - 3,3k…R16 - 12k…R17 - 300k
R18 - 1M…R19 - 1,5k…R20 - 8,2k…R21 - 1k…R22 – 24k ( 39k )…R23 - 4,7k
Capacitors .
C1-2, 2 ... C2-no.... C3-220,0 x 35V…C4-9100pf ( 10000 pf) ...C5-3000 pf...
C6-0,25 ( 0.22 ) ...C7-220,0 x 35V...C8-220,0 x 35V...C9-220,0 x 35V…
C10-0,1 ...C11-0,1 ...C12-0,1 ( 0.22-0.47) ...C13-22 pf ...C14-150 pf
Transistors .
T1, T2, T3-AC 122 ( Telefunken )
T4-GT308V.... T5-MP 37B
R1- 51k ( 75k ) …R2 - 220 …R3 - 56k …R4 - 6,8k …R5 - 270k
R6 - 36k…R7 - 820…R8 - 20k…R9 - 200k…R10 - 8,2k…R11 - 8,2k
R12 - 1,5k…R13 - 6,8k…R14 - 10k…R15 - 3,3k…R16 - 12k…R17 - 300k
R18 - 1M…R19 - 1,5k…R20 - 8,2k…R21 - 1k…R22 – 24k ( 39k )…R23 - 4,7k
Capacitors .
C1-2, 2 ... C2-no.... C3-220,0 x 35V…C4-9100pf ( 10000 pf) ...C5-3000 pf...
C6-0,25 ( 0.22 ) ...C7-220,0 x 35V...C8-220,0 x 35V...C9-220,0 x 35V…
C10-0,1 ...C11-0,1 ...C12-0,1 ( 0.22-0.47) ...C13-22 pf ...C14-150 pf
Transistors .
T1, T2, T3-AC 122 ( Telefunken )
T4-GT308V.... T5-MP 37B
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Hello, is it possible to upload the Germanium PSU/regulator schematics related with this phono amp?
in any case great job overall!!!
cheers Andy
Hello ! With this phonopreamp, I used a VLRA battery (2 pieces of 12 volts). 0.8 A / h . If you need a circuit of the power supply from the network - there is such a scheme . It outputs 32 volts ( there is an output adjustment ) . It has been successfully working with another germanium preamp for several years . I recently collected it again - for one of my friends . It uses germanium transistors . You can set the output to other voltages . .
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Another germanium phonopreamp . Made for one of my friends . Transistors-AC-122 and MP-21 . Power supply unit - P-213 and MP26B transistors .Vinyl Engine -Germanium phono preamp & power supply ... Vinyl Engine -Germanium phono preamp ...Vinyl Engine -Germanium phono board ...Vinyl Engine -Germanium power supply
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Thank you so much. I 'm in the process to assemble 2 MM phono preamps schematics from the very early times , one using OC44 , 2 stages and another one more complicated with AC107 and OC75. Both seem very promissing. I am thinking also to give it a try with tube rectification...Very ambitious in terms of hum issues...
I wish you success in the assembly phono preamp . I like the sound of germanium preamps . I have 4 phono preamps . And 2 of them - on germanium transistors . The sound is very good .
Instructions for Phono preamp SHURE M-61 on germanium transistors . The noise parameters are also specified there . View attachment ve_shure_m61.pdfI'm afraid that, compared with more recent designs, a Germanium phono preamp puts out noise like the Niagara falls
Best regards!
One of my phonopreamps is just made according to the scheme SHURE M-61 (Telefunken-TV 206) - on the original Telefunken transistors ...... About modern devices - if you are interested in OP-preamp, this is your choice . But it's not mine . ...And this topic is just about germanium preamps, not about modern devices ....I have 4 phono preamps, and among them there are devices with a noise level of minus 82 dB . So I have the ability to compare the sound
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I have a Phono preamp on 550/560 series transistors . But the germanium preamp sounds better . Although of course it has a little more noise .
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