Well got all my parts in yesterday and slapped her together in short order. This was from their schematic published on their Decware website and wired point to point (not using their ckct board). Was thinking I was going to seperate the shared cathode resistor but wanted to hear it as designed- getting 9.7VDC so Iam running 32ma thru each output tube so that puts me at around 92.5% bias-When running thru my bucking trans-115V they run 30ma each that puts the bias at 79% -they are strong military spec tubes and will be fine. Was wondering if the 10W 8K Edcors would perform well on the low end and YES they did (strong bass) I measured 1/2 a DB down at 40Hz and a perfectly flat response till 10K when it slowly dips even at 20K it's good. The power trans is hearty and over spec'd also- runs cool. How does it sound?? Well happy to report it sounds really good and punches well more than it's 2.8W would suggest. I've only been running it for a a couple hours but 1st impressions are great so far. If I were to build it again I'd have the output transformers back and the tubes in the front- with these Edcors they are top chassis mount- the Zen triode pre-built amp has a tube recetifier and the output transformers are in chassis.
Very nice! May I ask what chassis you used?
I built the version of this shown on the website with their PCB on a wooden board. It does sound nice with EL84 and 6DJ8 but I have to say I prefer the Skunkie 6BM8 sound, though the differences are subtle. Love the way you built this - looks really nice.
Here's the voltages I got if anyone else is going to build it (my live voltage at my house is 124.6Vac)- Iam using my 115Vac (bucking transformer) -it's really a great little amp and not many parts. the parts list are published on Decware's website. After checking bias and running performance tests - 115vac=79% bias 124vac=92.5% bias - my freq response and thd/power tests are running the same so 79-92.5% bias on output tubes equal same results. I will use my 115v as it tests and sounds the same as I will get longer tube life with the lower bias and heaters are right at 6.3v. with the over spec'd power transformer it will hardly even get warm running 12hrs straight.
Hi Danny, it's looking very good! It will need more than a couple of hours of running time to be at it's best as you well know, so that is encouraging. Is it quiet? Did you make the chassis or were you able to buy it from somewhere? Also I noticed that the schematic was revised quite recently, ie. 2021, so I wonder what was changed as the Zen has been around for a long time. Also, did you bother with the "Anniversary Mod"? It would be good to compare with and without.
I didn't realise that the DIY version had external output transformers. Those things are huge! I think If I built one I might be encouraged to build it into a deeper chassis and have them tucked away, although external is fine visually if they can be pushed to the back and shielded somehow.
I noticed that my Decware SE84UFO2.1 is still a long way off. I ordered a year ago and I see that they are only up to the July/August 2021 orders now. 😌 I hope the wait will have been worth it.