Rotel RT-870

[DanTana]

I've had this for some time. It had an intermittent problem I couldn't figure out. Turned out to be a loose solder joint on one of the TO-92 transistors. I resoldered it and it's been working fine ever since. I bought a JVC FX-1100BK in the meantime and modded it while I had used the Rotel. Now that I have the Rotel out, it was time to try some mods on it. First thing I did was swap all the 1N4003 diodes for 250v 40a Schottky's. There were 9 of those to replace. I then began swapping out capacitors with bigger value ones. I doubled the size of the first 2-3 caps directly from the transformer, and most of the other caps as well. I then replaced the D313, with a TIP31C. Put it back together plugged it in and a capacitor blew up, first time I had ever done that before. Turned out, the PCB showed negative on it, I put in the new one accordingly, however, the regulator was reverse polarity than the capacitor it was wired to, so poof it went and I rewired it the other way and it was fine. Goes to show...never trust the PCB markings. I replaced a couple other caps on the board, mostly the 10uf, and 47uf ones. There are a ton of 100uf caps but I ran out of them. I then put it back together once more and now it closely rivals the JVC for sound quality. I need to do more A/B testing but I think the Rotel beats it in overall sensitivity, and possibly selectivity also. I also like how the Rotel is all manual with the "Hi-Blend" and narrow and wide modes, it also has a "AM Wide" selection. The JVC when auto tuning sets the quieting "QSC" and wide and narrow modes, the wide and narrow you can overwrite, but not the quieting. The Rotel also has an interesting internal adjustment for the filtering at the end of the output section. I think it adjusts the roll-off of the high frequencies. So far, the bass is better with the Rotel. I think the JVC wins in the highs and imaging/soundstaging. I do like the JVC's dual antenna feature too. This is a nice problem to have, both now are very good sounding tuners and for now I'm going to use both.