[rjm003]

6CG7 + several 2SK213s, mu-follower topology with additional MOSFETs as line smoothers. It took me two years to get around and finish the thing, and the concept - a single tube headphone amp - has been kicking around my head for more than a decade I guess. It ended up a bit bigger than I originally planned, but overall I'm really pleased with how it turned out.

Most importantly, it glows:

When it not glowing, it looks like this:

The insides are pretty messy and look like this:

Finally you can peruse the circuit schematic here: (large, so I wont embed it)

http://i55.photobucket.com/albums/g1...ht_circuit.png

The circuit puts about less than 10W heat including the filament, and gives about 40 mW (calculated limit at 1% distortion) output power into 300 ohms. Hum and noise below 0.2 mV, and inaudible.

Given that you need a 60 V secondary, and ideally the 2SK213s, this isn't ever going to be one for the masses. It's rewarding, though, if you are willing to go this distance with it.

/rjm

 

[TzeYang]

i cant believe what i'm seeing here, it's absolutely beautiful.

I really really love the simplicity of the circuit. It's...just...elegant.

 

[pmillett]

Quote:

Originally Posted by rjm003 /img/forum/go_quote.gif 6CG7 + several 2SK213s, mu-follower topology with additional MOSFETs as line smoothers.

Excellent design, and beautiful execution.

Quote:

The insides are pretty messy and look like this:

Messy? You're kidding, right? I don't know that it could be much better...

Pete

 

[fierce_freak]

Very nice...I'm certainly far, far from an authority on this, but I think it looks like a nice scheme. If pmillett thinks it's a nice design, that only confirms for me that it is. I have a pair of 6CG7's sitting around doing nothing, so I'm going to consider putting one together in the future.

 

[Budgie]

Nice. When will the kit be avaliable?

 

[fortney]

Lovely job, inside and out.
2 questions--
How does it sound?
Does the heat sink get hot? If so, it would make a fine winter amp here in Wisconsin.

F

 

[Marzie]

Any plans to put the Eagle files on your site? The first two replies on this page sold me on the fact that one way or another, I will be building this amp...

 

[dBel84]

The files are posted over @ HW , truly great work imo..dB

 

[Marzie]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif The files are posted over @ HW , truly great work imo..dB

Ahh, and here I've been taking a crash course in Eagle for the last 2 hours. Good learning experience, though.

 

[Uncle Erik]

Very nice work!

Do I really need another project? I get the feeling I'll end up with one of these.

 

[rjm003]

Thanks for the kind words. If you have any questions I'll do my best to answer them. Except for "how does it sound?" part. That will have to wait for a bit.

"When is the kit available?"

I realise that was only half-serious, but I don't think the Twilight project lends itself to being packaged as a kit. Too much, like the transformer, is out of the mainstream.

"How hot does the case get?"

The MOSFETs and the source resistor are bolted to the case with a large 4 inch square heatsink on top the whole thing is just pleasantly warm to the touch. Its not even any good as a hot plate to keep my coffee warm.

"Any plans to put the Eagle files on your site?"

I will attend to that shortly. I've just updated the Twilight homepage, basically putting there what I just posted here. I'll do the Eagle files shortly.

/rjm

 

[Marzie]

Anyone able to translate the eagle files to Autocad? I would like to add things to the layout like space for heatsinks, the tube socket, and the wiring that was done point to point. I can get autocad from work, but I don't think we have the "inventor" software that does translation. Anybody else interested in this? Or would it be mucking up a great design?

 

[rjm003]

Quote:

Or would it be mucking up a great design?

No, definitely not. Its the way it is only because it had to fit on 100x160mm. The point to point stuff isn't that difficult, but it would help to use a terminal strip next to the socket to provide additional lugs for supporting components. I regretted not using one.

Also note that IRF510 do not share the same pinout as the 2SK213, so chances are you'll have to redo large sections of the PCB regardless.

 

[pmillett]

Quote:

Originally Posted by Marzie /img/forum/go_quote.gif Anyone able to translate the eagle files to Autocad?

Eagle has a ULP called DXF. Just turn on all the layers, do a "R" to fill the copper, and run DXF.

It will generate a multi-layer DXF file (each layer on it's own... layer...) It can get painfully large for a big PCB.

You can then open the DXF in ACAD, or insert it as a block.

Pete

 

[borisov57]

Beautiful. Are those black resistors Welwyns?