Someone can ask why it took so long for me to ever build any at all RIAA amplifier. I can only wonder myself. Lack of time, family obligations, house, work and so on. I allways had the drive but i also had high demands on the projects building and how it would look... so i never tried. I just imagined how I would do it when I eventually got the power to do it. The Internet and all the communities finally got me going. This project I found on the DIY audio forum, the best one there is. Read about the DIY phono preamp - cheap and simple!
After all those years of waiting i did this little amp in 3 days on sparetime! Instead of external AC I use an allready regulated DC unit (switched psu) outside this amplifier. The inbuilt regulators on top of that ensures very clean DC power. As one can see I also used carbon resistors as load impedance for the MM cartridge. Some people say they can hear difference against metalfilm and that they are better in the inductance aspect. Other ones says they are noisier so .. I'll maybe switch them some day. I doubt I can hear any difference though.
RJM's DIY printed circuit boards in Eagle format was offcource the kickstart. I was eager to get something better then this one ....
This "HQ PRE MP 220" phonoamp has served me for several years. I had to modify it though. The 220V AC transformer was spreading it's hum all over the card :-) I fixed another external PSU to get rid of the hum. But if I compared CD titles with the vinyl ones there was definately to much bass with this one. There is some more reading of this amp out there. From the beginning it seems to be from an early DUAL, discrete transistor design from the 60's. Read about this one and his cousins.
There is also another thread by RJM which is useful if you would like to build one of the slightly different models he have. On the DIY audio forum the thread is The Phonoclone and VSPS PCB Help Desk.
I havent yet been i contact with RJM. I should thank him for making me move my butt and finally do my own reference one RIAA amplifier :-) .
When it comes to A/B tests with the same music on CD the overall frequency responce is spot on. So maybe the "Allen Wright" curve of the RIAA curve is the way to go. The one thing I dislike is that there is to much pops and clicks. Can it be to little "headroom" from the PSU or something else? I have to read and learn more about it.
Does it sound more pleasing then my Marantz CD65II? Sorry to say no. There is to much clicks and pops to be really enjoying.
Please look at my progress with my second reference phono stage. It will be with tubes accompanied by some solid state.
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