My friend brought me another amplifier to fix about a week ago. This amp is the Harmony H304 guitar amplifier.
This amp was probably built in 1960, the date on the power transformer is December 1959, so I'm guessing either 1960 or 1961. This amp is all tube powered. It has a 6V6GC power tube, a 5Y3 rectifier tube, and two 7 pin preamp tubes that you don't normally see in a guitar amplifier. Normally you would see a 12AX7 which has 2 triodes built into it. The two single triodes do the same job as a twin triode tube, but you need 2 tube sockets for the preamp instead of just one for the twin triode preamp tube. This amp will put out about 4 to 4 and a half watts of power to the speaker. The amp only has 2 controls, a volume and a tone control. The cabinet on this amp is not in the best condition, but the amp is almost 60 years old and you can see that it was well used. The grill cloth is in remarkably good condition, considering it's age. It may, or may not be original.
When the amp was brought to me, it was partially disassembled, so I basically just had to put it back together and replace the necessary parts to make it functional. I pulled the chassis out of the cabinet so that I could get at the parts to do whatever needed to be done.
There's really not a lot of parts in this little amp, just enough to make it work. The power supply capacitors had been replaced in this amp, apparently in 2004, judging by the date written on the capacitors, and the power cord had been replaced with a 3 wire grounded plug, probably at the same time. The original power cord would have been a 2 wire cord, the 3 wire cord is a safety measure against possible electric shock. I ended up replacing both the volume control and the tone control, the rest of the parts seemed to be ok.
Another interesting part of this amp is the 6 inch Jensen alnico speaker that is original equipment in this amp. This speaker sounds better than any of the 8 inch guitar speakers that I've heard. The old alnico speakers don't handle a lot of power, but they really do sound good. The speaker had 2 wingnuts holding it in on 1 side, I replaced them with lock washer nuts that will stay tight. The wingnuts were loose with no lock washers to keep them tight. It's important that the speaker be tight in the cabinet to prevent rattling and cabinet buzzing.
Of course, I had to test the amp after I put it back together. I decided to make a video to demonstrate the sound of the amp after I was satisfied that it was working properly. This amp doesn't get really loud like bigger amps do, but it certainly gets loud enough for any room in the house. Here's the youtube video link.
I thought about putting the video on Dtube, but the rest of the post would be difficult to write from the Dtube uploader. I would have had to edit the post on steemit anyway to put the pictures into the post, so I decided to just write the post on steemit.
That's all I have for this post, I hope you found it interesting!
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