This pre-amplifier was published in 1994 in Elektor.
https://drive.google.com/file/d/1gFx9xPYtoKBOYfyoPnygX1_ZdWmwhsKf/view
Problem is that I don't see the volume control for it.
I know it's a noob question but where to put it and what value should it be?
https://drive.google.com/file/d/1gFx9xPYtoKBOYfyoPnygX1_ZdWmwhsKf/view
Problem is that I don't see the volume control for it.
I know it's a noob question but where to put it and what value should it be?
Connect the pot before C1, with the wiper to C1, and the pot bottom lead to ground.
Input goes to the top lead of the pot. Normally 10k is suitable, unless you have a tube source.
Input goes to the top lead of the pot. Normally 10k is suitable, unless you have a tube source.
Are the matched BJT pairs MAT02, MAT03 still available? If not, are their modern contemporary equivalents available?
Finding MAT02/03 will be tough (and expensive). That design is from 1994, today's opamps have quite good properties. Besides that you likely won't need much gain either. Since it is essentially a discretely built bipolar opamp the JFET OPA828 would be a very good substitute and the DC servo probably would not be needed. Or eh... no preamp at all. Just a buffer with source selection and volume control.
For the NPN pair, SSM2212, if I'm not mistaken. SSM2220 is a PNP pair, but I can't find it on the Mouser site anymore. The THAT300 series is also rather similar. The packages are different from the old MAT02/03, I'm not sure about the pin-outs.
If hFE doesn't matter much, if 2 mV matching suffices and if you don't mind SMD packages, BCM56DS and BCM53DS might be interesting.
If hFE doesn't matter much, if 2 mV matching suffices and if you don't mind SMD packages, BCM56DS and BCM53DS might be interesting.
SSM2220 is 19 Euro, SSM2212 about 8 Euro. Both won't fit on the Elektor PCB so you have to add the time, effort and costs to draw a new PCB 🙂 OP77 starts at 8 Euro. It is all quite some required energy to build that 1994 design. It would not surprise if the matching of the on die semis in opamps is better than that of discrete ones.
That is the price one pays to build old designs with substitute parts. OPA828 costs 6,19 a piece. Low part count, affordable, small, stellar performance.
That is the price one pays to build old designs with substitute parts. OPA828 costs 6,19 a piece. Low part count, affordable, small, stellar performance.
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Oh, has it been that long?
I still have two of the assembled boards in my collection box, but I've never used this preamp.
rayma has already answered the actual question.
+1
I still have two of the assembled boards in my collection box, but I've never used this preamp.
rayma has already answered the actual question.
+1
Yeah DIY audio is an efficient hobby 🙂
Unlike you maybe the OP does not have the boards in a collection box. Then he now knows how to connect the volume potentiometer and that building it in 2024 will be an expensive affair. In a perfect world non used and stuffed PCBs could go from the person that has them but does not use them to the person that does not have them and wants them but that is Utopia and we are living in Europa.
Unlike you maybe the OP does not have the boards in a collection box. Then he now knows how to connect the volume potentiometer and that building it in 2024 will be an expensive affair. In a perfect world non used and stuffed PCBs could go from the person that has them but does not use them to the person that does not have them and wants them but that is Utopia and we are living in Europa.
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funny, I had thought of that too - well, I can be reached via PM.
#
Although I don't like to say it, because you and I don't like each other very much, but:
I also advise against replicating this SuperDuper94Pre. After all, it's not resting in peace in the box untested. But the treasure can be unearthed.
HBt.