Back in February of this year I ventured into the world of Tube amps and purchased the subject amp on Amazon. At the time I was refreshing a pair of Klipsch Forte' IIs and kept seeing how often they are mentioned for playing well with low watt amps like this one. After a few upgrades on the Forte’s which included configuring them for biamping I took the plunge on this low cost entry level 300B amp. Performance was better than I expected until a few weeks ago when it failed to power on. Replacing the 4A fuse integrated into the power connection port did not resolve the problem. After some trouble shooting advice and few more blown fuses I determined the rectifier tube was suspect. Unfortunately finding a place to check out a tube locally is no longer as easy as stopping in at Radio Shack or the TV repair store – at least not here in Huntsville, AL.
A friend suggest I contact a guitar store for a possible lead and sure enough I was recommended to a local gentlemen that was able to not only check out the tube, but also do a little diagnostics on the amp itself based on the limited schematic information that Stephe has made available. Turned out that in addition to the rectifier being blown, the LC was only outputting about 1.5 watts – so something else appears to be wrong in the circuitry. He also recommended using a $10 dollar SS 5AR4 rectifier to eliminate the cost of another tube rectifier. Has anyone else tried this?
With a little help from Amazon I was able to get in touch with the "TubeAmplifierStore" who is still selling it on Amazon. Initial communication from them looked like they might attempt a run around on warranty service. I provided a second response with photos and the detailed notes from the tech that checked it out for me along with sending an email directly to "China-hifi-audios.com" where the one year warranty is clearly posted. Not sure what got traction but I soon received instructions for packaging it back up and along with a prepaid UPS label to return it. The “to address” CHFRC appears to indeed be China HiFi in Racine WI, apparently they go by TubeAmplifierStore as a storefront name on Amazon.
So it is on the way and we shall see what they do to correct the problem. I'm hoping they simply send me a brand new unit that perhaps has some of the upgrades/improvements that are much talked about on the web.
Meanwhile I connected my old 1973 Fisher 170 Receiver using the Aux in L/R channel from my A/V pre-amp to power the mids and tweeters on the Forte's (same configuration I was using with the A50). I must say it sounds really good. Looking forward to setting the returned A50 300B right on top of the old Fisher and being able to do quick A/B comparisons for sound quality. Should have done that from the beginning. I’ll update this post once I get the A50 back.