Just a little thread where I'll document my Decware Zen clone. Decided to remove the full metal jacket just...because.
after:
These are the little output transformers used in the Sony R2R. Because the Zen wil be around 2 Watt. The have nice core material that is very thin and the appear to be made very well.
after:
These are the little output transformers used in the Sony R2R. Because the Zen wil be around 2 Watt. The have nice core material that is very thin and the appear to be made very well.
Nice! I don't want to pollute your post, but I am almost done with my Decware Zen clone too!
Will add better photos but these are some details:
Right now I have a it of low voltages, only 5~v at the EL84 pin 3 test point. I suspect the choke + 80 rectifier are giving me lower voltages then the comparable Zen with solid state rectification.
I was planning to try reduce the value of the first 1k resistor in the power supply until reaching the voltages suggested in the Decware Zen docs.
To clarify I am a beginner and don't know much yet about building tube amps, so surely I have made and will keep making lots of mistakes.
So far I've turned on just one unit, it was humming a bit. It sounded like a higher pitch hum, not 60hz, maybe 120hz? I will have to look more into it.
The heater of the preamp and power tube do not have center tap at the moment, as the transformer doesn't have a center tap for the 6.3v winding.
Hope we can learn from each other's build!
Will add better photos but these are some details:
- power transformers are some old potted ones with the specs seen in attached photo
- I forgot what the chokes are, some vintage potted ones, i have to see if i find pictures of the specs before being painted
- 2x vintage oil caps 8uf Sprague 600v (forgot the exact voltage) paralleled in each monoblock, coming after the choke
- implemented some of the mods included in the 2019 ZKIT-1 Manual With Anniversary Mod schematic, in particular paralleling smaller film caps in the power supply
- rectifier is 80
- output transformers are Electra-Print 300B Enhanced A3 Output Transformers 9.5k @ 60ma
- I will use vintage Siemens 6922 branded RCA made in Germany
- I will use 2x globe 80 rectifier
- I will use some vintage EL84, but I would like to try 6973 in its place. I really like the sound of some Ampex monoblock I have with 6973, much more bass-y
- I have used CL-90 and CL-130 for soft start
Right now I have a it of low voltages, only 5~v at the EL84 pin 3 test point. I suspect the choke + 80 rectifier are giving me lower voltages then the comparable Zen with solid state rectification.
I was planning to try reduce the value of the first 1k resistor in the power supply until reaching the voltages suggested in the Decware Zen docs.
To clarify I am a beginner and don't know much yet about building tube amps, so surely I have made and will keep making lots of mistakes.
So far I've turned on just one unit, it was humming a bit. It sounded like a higher pitch hum, not 60hz, maybe 120hz? I will have to look more into it.
The heater of the preamp and power tube do not have center tap at the moment, as the transformer doesn't have a center tap for the 6.3v winding.
Hope we can learn from each other's build!
Attachments
I want to try that in the next few days and see if it helps with the hum. I'll post pictures of the wiring as well. Probably I'm doing something wrong with how I route and twist them too.
I thot they looked familiar, TamRadio quite decent. Once you are done are you going to improve it, the ZEN is OK but can be much better. I expect with the better OPTs you are already heading in the right direction.
dave
Adding a choke to the PS and using all poly caps are 2 simple things that improve on the ZEN.
We used the 10H Hammond choke and all Solen caps.
dave
I was planning on using a 10H choke. And know that you guys used Solen caps. I might go all pp caps as well..except for bypass of cathode. Won't change it much I think because I want to compare it sort of for what it is. A tube rectified...6n1p and sv83 wired as triode se amp.
And here is my measurement of the OPT.
Are you also using the (very nice) power tranny? Considerably beefier than on a the Zen. You have to feed 2 less triodes and 2 6AU6, is that enuff current for the hungry 6H1∏ filaments?
You might want to see if you can get a pair of 6П14П, much beefier than the SV64 (6П15П)
dave
Are you also using the (very nice) power tranny? Considerably beefier than on a the Zen. You have to feed 2 less triodes and 2 6AU6, is that enuff current for the hungry 6H1∏ filaments?
You might want to see if you can get a pair of 6П14П, much beefier than the SV64 (6П15П)
dave
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Not sure if that suggestion was for me. I have plenty of the 6П14П. But my aim is to do something different than my recent SE el84 amps and as the original Zen used sv83. I'm planning on using them.
PS...Almost all round holes done. Just the rectifier octal tube socket and power switch and then the transformer cutout.
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Nope. Since I don't have one. But I've got a great 270-0-270 (250mA) 6,3 (5A) locally built transformer (Vlaartronic). Pimped in my two tone look. With extra breathing holes (not perfectly aligned but good enough)
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