Monday, November 16, 2009
My parents were in town this past weekend for another visit. This time my father and I had more time to spend working with three amp projects. First we looked at the Champ 5E1 project that started all of this. We confirmed that I do not have a center tap on my RCA power transformer so my options are to either create an artificial tap and use the 5Y3 for rectification, or create a bridge rectifier using 4 diodes, donated by my neighbor (thanks Bryan!). Next we spent time slowly powering up the Western Electric 124c Dad pulled out of the town dump! This thing was THE workhorse of the early '50s. As you can see in the photo above, this amp has 19" rack mount ears on either end of ths chassis and a full-size face plate that mounts on the bottom which is actually the front. Click on the photos to see larger versions.
The third amp was the Hammond AO-35 which was donated by Ron Ashcroft last year. I installed new tubes which I bought at the Dayton Hamfest in June 2008. These were two Sovtek EL-84, two Svetlana 12AX7, and a NOS Sylvania 5Y3 made in 1975. We slowly powered this up as well, using the variac I bought at the '08 Hamfest. This amp has no gain control pot, so after a little squealling with a microphone, we plugged my Samick Telecaster in using the Switchcraft adapter I bought from Antique Electronic Supply (visible on the right of the chassis). The amp sounds good, but a thorough test of all the parts will likely turn up some leaky caps. A gain pot would also be helpful.