The “Retro” balanced RIAA stage

Since I got my Pro-Ject turntable about two months ago I have been looking for a decent RIAA-design. I have an old Vincent, but it isn’t really good enough. Almost at the same time, I realized that Brian and Russ at Twisted Pear Audio were just finishing up a balanced RIAA design using differential opamps which they called the Retro. It looked like it might be worth a try, so I ordered some PCBs and the few parts that I were missing – sometimes it is nice to have a big cache of parts that can be used 😀

The build is dual-mono including power supply boards (the LCBPS also from Twisted Pear) and separate PCB-mounted transformers for each channel. It is a bit overkill with two transformers, but hey, they were just laying around anyway 😉 The observant reader will notice from the pictures that my ground wiring isn’t 100% correct – I am still trying to get my head around grounding in differential systems but for now it works fine with only a little hum in the speakers.

I haven’t spent two much time listening yet, but even with short tests it is obvious that this design is at least a few steps up from the Vincent, so although I have a few more RIAA-designs I would like to try as well, the Retro is definitely making the Pro-Ject (and the vinyl collection) sing 🙂