Well, yeah, without even a schematic the best I can do is some seat-of-the-pants speculation. I vaguely recall the "Cortina" series products from about 1970. Given the general improvement in device performance over the intervening 40 years I'd suggest that the BC550 (NPN) and BC560 (PNP) would be acceptable substitutes for just about any small-signal transistor likely to be found in the preamp section.
If the devices are definitely faulty, a more significant question is what caused the failure. Again going on the age of this unit, a wholesale replacement of electrolytic capacitors may be a wise first step.
Dale
If the devices are definitely faulty, a more significant question is what caused the failure. Again going on the age of this unit, a wholesale replacement of electrolytic capacitors may be a wise first step.
Dale
2N2222's should work OK. You don't need change any components for using different transistors in this circuit. Make sure you identify the connections correctly... and if you have the choice get some more modern devices like the BCxxx devices mentioned. If your 2N2222's are metal encapsulated then that makes them less of a good choice due to possible pickup of noise and hash... which I guess in a phono stage is important.
Tandbergeren,
Your offer is most generous, thank you but that will not be necessary. If you have a better schematic of a transistor riaa pre amp I would accept that.
I am retired and need something to keep my mind active so I decided to built
the EICO pre amp. I'm just having fun.
thank
Bruce
Your offer is most generous, thank you but that will not be necessary. If you have a better schematic of a transistor riaa pre amp I would accept that.
I am retired and need something to keep my mind active so I decided to built
the EICO pre amp. I'm just having fun.
thank
Bruce
Have a search for the Radford ZD22 and HD250 amps. Classic all discrete single rail design and hard to better even today sonically.
After some suggestions, I choose the transistors as indicated on the schematic.
I am very happy with the results, highs and bass are all present. I don't know how to evaluate the sound so I have no idea what the distortion is or even the frequency range. Having said that, it sound pretty good to my old ears.
I am very happy with the results, highs and bass are all present. I don't know how to evaluate the sound so I have no idea what the distortion is or even the frequency range. Having said that, it sound pretty good to my old ears.
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