Photo Gallery

[icebear]

A picture of my decware clone.

[icebear]

The bottom:

[resident]

@rdf
Don't you have hum problems with that kind of transformers placement?
The power tranny is that on the back(middle),right?
I have tried it at my last project and I had serious hum problems and now I'm rebuilding it.

[rdf]

None that I can ascribe to tranny placement. The amp uses a simple C-R-C supply but hum and hiss are completely inaudible more than 4" from 89 dB eff. speakers in a dead quiet room. What little remains is 'clean' and sounds more 120 Hz than 60 Hz so I took it to be due to the simple supply. The ground plane construction helped. Mind you, the Mullard circuit uses global negative feedback too, which plays a big part in hum reduction.

[bobhayes]

I've just completed my first DHSET amp. It's based on the JE Labs 6SL7/2A3 design with some changes... Mainly I built my own C Cored transformers, which were easy enough but very time comsuming. It was a project while I've been in Oz.
Other changes are mainly to the PSU to use 5U4G and bring the voltage down a bit. A choke load resistor to bring the PSU resonance down too, and easier to find components.
The only thing to do now is make a nice Jarrah (oz timber) plinth to replace the temporary plastic one I knocked up. I might play with the coupling caps too, although the polyprop mains snubber is ok.
The home made covers are removed to show the transformers.

For two days I,ve been rediscovering my CD collection, conclusion...
Sounds very nice.

Just had to tell someone.

[Bas Horneman]

Congratulations on your build!

Where did you learn to wind your own transformers!?

Regards,
Bas

[bobhayes]

A bit of college teaches the basics, but more useful practical information came from posting a couple of questions on this forum and did a little research on the web. There are a few good sites with a 'how to' approach and the rest is just getting the bits together and plenty of time to do some number crunching a a lot more time to wind them by hand!
If you have some spare time I'd recommend it as you'll get a superior item for a lot less money than commercially available transformers, and there's nothing better than doing it yourself!

[resident]

@bobhayes
Very nice amp.Give us a foto with covers,too!
Where did you find those bobbins for the transformers?
You bought them or are handmade?
What kind of C-cores you use?

[bobhayes]

Here's a picture with the covers on.

I got all the cores and matching glass fibre bobbins from a local three phase transformer winder. He was very helpful, giving me the web address of the manufacturer, to choose the appropriate cores, then ordering them for me.

He also gave me a nice few spool ends of enamelled wire to wind them with!

The cores are manufactured and imported by AEM cores in western australia, but I'm not sure about the bobbins as the whole lot actually came from south australia.

[kmtang]

Here my little monoblock 45/2A3 power amp based on the JE Lab design using 6SL7 as driver, Hammond power transformer/choke/1628SE OPT.


Johnny