2A3 SE - The Beginning
What topology to use is a matter of requirements for the outcome, finish and way, method or ease of construction. I used to go for push-pull to get more power, but today I am into single ended designs as they are easier to build and require less components.
This is to describe a project I have dreamt about for a long time - a DHT amplifier. I figured that 300B was a bit expensive, an 811 or 211 or GM70 required to much volts. A 2A3 was maybe the most perfect choise for an "experiment", especially as the tubes were offered at a very attractive price.
Fig 1. The chassis will be made from a number of pineboards 245 by 300mm sandwiched together. Tob board will have cut outs for tube sockets and wires from transformers and choke.
How to make arrangements for connectors and potentiometers and switches I haven't really figured out.
Fig 2. When finished it will look something like this. The blue OP-transformers are from Edcorusa and are slightly overkill with their rated power of 20W. The mains transformers is not correct and will propably be replaced by a similar. Not seen are the two driver tubes 5824.
Fig 3. Transformers, choke and a 2 x 2,5V transformer. All posing on a slightly smaller beech board - but noticed when I had gotten the transformers home that it was too small and that components had ended up to close to each other.
Fig 4. When picking passive components I am go for cost/quality. No fancy overpriced crap here because a Golden Ear has said that tantal resistors sound better. The potentiometers are for balancing the heaters - 2W, cehap from German (Swedish) Conrad.
Missing some stuff for the PSU and I guess I have nicked som components for other projects!
Fig 5. Tubes are 2A3 from Chinese Valve Art, 5842 are NOS Raytheon and 5AR4 a Russian RUBY-tube.
