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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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In Reply to: I like these Welborne300b amps with Elektraprint transformers. posted by Michael Samra on April 9, 2014 at 23:15:17:
I bought a pair of these amps about five years ago on epay. Mine have the rectifier tube and were a kit assembled by a very competent tech. They sounded fine, but this is a DIY hobby and my least favorite part is building the chassis so I bought these as a platform upon which to build my own version.
I replaced the 300B with a 2A3 and added a 2.5V filament transformer. I added a volume control and moved the RCA jack next to the volume pot. Since the 2A3 tubes were making expensive sounding noises on power up I added a switch for the filament transformer. The existing power switch powers on the B+ and the JJ caps were replaced with a Mundorf. This required making a new panel on the back to replace the Welbourne panel. I moved the speaker posts to a spot near the output transformer and added a hum pot on the panel along with a fuse holder.
I changed the input tube to a 6N23P-EV and biased it with a diode. In the process of these mods I removed about a foot of wire and tightened up the layout. The filament supply for the 2A3 is AC so the discrete diode bridge is not used and the filament choke was removed. Note the extra resistors added to the 2A3 cathode resistor to dial in the operating points. The upper left transformer is the plate choke and the bottom left is the power supply choke. There are only three capacitors in the amp.
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Follow Ups
- RE: I like these Welborne300b amps with Elektraprint transformers. - Palustris 10:13:12 04/10/14 (0)
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