DIY 6T9 Tube (Valve) Single-Ended Amplifier Kit

Posted on Feb 5, 2014

The PCB for this amplifier can be purchased from Spare Time Gizmos for $16US. In a single afternoon you can have the whole board assembled and dropped into a chassis of your choice. The value and type of component is laid-out in the parts list. But what I like to do is to put my own twist on each amp I build. If you are not an experienced valve am

DIY 6T9 Tube (Valve) Single-Ended Amplifier Kit
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p building follow the parts specification to the letter. I increased the input and coupling capacitors to 0. 22 uF and used polypropylene types. These components are physically larger than what is meant for the PCB so some manipulation is required. I also like to use snubber capacitors across any possible noisy components such as 0. 01 uF poly caps. across the diodes and 1 uF capacitors across the filaments of the valves. Snubbers on the filtering caps is also a good idea and I used 0. 1 uF polies. I added an extra 200 uF of capacitance to the power supply and found that this helped the bass response. I used a Hammond 369JX power transformer and Edcor XSE15-8-5K for the output transformers (OT). A smaller OT can be used but expect the bass and treble to suffer. The Edcor OTs are very reasonably priced and also have a ultra-linear (UL) tap so you can run the amp in true UL mode. I mounted the tube sockets on the back of the board so I could expose the cute little hot bottles outside the chassis. A drilling template is provided with the boards. Instead of an expensive chassis I used a $7 cooking pan. Drilling thin metal can be more problematic than drilling a heavy chassis, so be patient with drilling. I mounted the power and OTs on rubber grommets that were sliced in half. This was done to reduce the potential for transformer vibrations reaching the tubes which can be microphonic. The thin chassis is mounted on thick...

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