Dear all,
Recently I have built a very simple RIAA preamplifier (for a moderate output moving coil cartridge) and line stage, in order to play LP records and CDs in our living room. Since my power amp (Van Medevoort PA222) has no volume or level controls at its input, I needed a preamp. The preamp was built using parts of the junkbox, and all PCBs were homemade and home-designed. Since I did not use anything special, I didn't expect much, but the sonic results were excellent. Thus, I will present my little project in a few posts to this forum, starting with the RIAA preamplifier.
The RIAA preamp circuit that I used was published by John Linsley Hood, in the magazine Electronics World + Wireless World, June 1993 ("An Integrated Audio Amplifier"). John used two LM833 op-amps, which I replaced by two NE5532s (Philips) since I did not have LM833s in the junkbox. An "input impedance conversion stage" (linear gain block) is followed by a RIAA equalisation stage with shunt feedback. Although the use of shunt feedback rather than series feedback results in higher noise, the reproduction of transients by a shunt feedback system is superior. And I can report that the noise of this preamp is not objectionable, in fact, it is much lower than the surface noise of most LPs. All my capacitors were of decent quality and good accuracy. Styroflex and MKP types were used for the RIAA network, input and coupling caps, low ESR types for the electrolytics and multilayer ceramics for decoupling of the power supply lines. A kit for the RIAA preamp has been supplied by Hart Electronics ("K1500 Shunt Feedback RIAA Preamp"), but that company no longer exists.
Although I used ICs that can be purchased for 26 Eurocents (e.g. from Pollin in Germany), the preamp sounds great! This was also reported by David Hembrow, a UK citizen living in the Netherlands (see his homepage at hembrow.eu). Very minor details in recordings are revealed, and the placing of instruments on the soundstage is very accurate. The soundstage is both wide and deep. Improvements are perhaps possible (one could e.g. replace the first opamp by a "better" type such as the SSM2139), but right now, I'll leave everything as it is. I'm happy listening to my old records..... In case you wonder: I use an Audio Technica OC30 mc cartridge mounted in a Pioneer PLX-1000 direct drive turntable. And my speakers are exponential horns (Jericho horns with Fostex FE208 Sigma fullrange drive units).
To this post I attach: a. Circuit of the preamp; b. Bottom side of my home-designed PCB; c. Top side of the PCB (please note the presence of two wire links).
Best regards,
arensattic
Recently I have built a very simple RIAA preamplifier (for a moderate output moving coil cartridge) and line stage, in order to play LP records and CDs in our living room. Since my power amp (Van Medevoort PA222) has no volume or level controls at its input, I needed a preamp. The preamp was built using parts of the junkbox, and all PCBs were homemade and home-designed. Since I did not use anything special, I didn't expect much, but the sonic results were excellent. Thus, I will present my little project in a few posts to this forum, starting with the RIAA preamplifier.
The RIAA preamp circuit that I used was published by John Linsley Hood, in the magazine Electronics World + Wireless World, June 1993 ("An Integrated Audio Amplifier"). John used two LM833 op-amps, which I replaced by two NE5532s (Philips) since I did not have LM833s in the junkbox. An "input impedance conversion stage" (linear gain block) is followed by a RIAA equalisation stage with shunt feedback. Although the use of shunt feedback rather than series feedback results in higher noise, the reproduction of transients by a shunt feedback system is superior. And I can report that the noise of this preamp is not objectionable, in fact, it is much lower than the surface noise of most LPs. All my capacitors were of decent quality and good accuracy. Styroflex and MKP types were used for the RIAA network, input and coupling caps, low ESR types for the electrolytics and multilayer ceramics for decoupling of the power supply lines. A kit for the RIAA preamp has been supplied by Hart Electronics ("K1500 Shunt Feedback RIAA Preamp"), but that company no longer exists.
Although I used ICs that can be purchased for 26 Eurocents (e.g. from Pollin in Germany), the preamp sounds great! This was also reported by David Hembrow, a UK citizen living in the Netherlands (see his homepage at hembrow.eu). Very minor details in recordings are revealed, and the placing of instruments on the soundstage is very accurate. The soundstage is both wide and deep. Improvements are perhaps possible (one could e.g. replace the first opamp by a "better" type such as the SSM2139), but right now, I'll leave everything as it is. I'm happy listening to my old records..... In case you wonder: I use an Audio Technica OC30 mc cartridge mounted in a Pioneer PLX-1000 direct drive turntable. And my speakers are exponential horns (Jericho horns with Fostex FE208 Sigma fullrange drive units).
To this post I attach: a. Circuit of the preamp; b. Bottom side of my home-designed PCB; c. Top side of the PCB (please note the presence of two wire links).
Best regards,
arensattic