Here is the amp nearly done, from the front. As mentioned earlier, this would be the time that I would debug the amp for possible problems. Well, on this build I had no appreciable B+ voltage, even though the rectifier was working fine. Those silly electrolytic capacitors were all in there backward. Usually the marking is very clear as to which side is negative. The black stripe with no arrow wasn't helpful for me. I wrongfully guessed that the black stripe corresponded with the black end cap, marking that as negative. Duh, that black cover was on the crimped side, and usually it is there to insulate it from the casing. The casing is usually grounded, and the negative side is silvery. Well, it could have been worse for debugging, and luckily I did not destroy these four capacitors ($2.50 each!).
Here you can see that I sketched a part of the schematic on the back of the amp. It is the preamp stage. I wrote that this was "BlackLine Amp Serial Number: 00002," except that I mispelled it "BlachLine." Oh well. Look in the back of the workbench, I installed a permanent 1/4" audio jack for my amp building projects. It is connected to a speaker only for this purpose.
...and that speaker is mounted to the ceiling of my workshop! This is a nice 12" speaker from an old Dean Markley amp from the 1980s. I can sort of use it for some hi-fi stuff as well for basic debugging. The sound is weird coming from the ceiling! Behind that you can see the workshop clock mounted on my little data closet. Inside that small room is the nerve center for all the phone, cable, satellite, and ethernet connections.--gh
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