[Tomo]

Hi,

http://www.ndh.net/home/kboehm/SE-2x1w.htm

I think it is very usable. I found it long ago, but I lost the link. Now I have it. So I am posting.

T

 

[jeffreyj]

Hey Tomo,

I thought Morgan Jones pretty well thrashed the use of AC for the filaments, especially in the case of directly heated triodes?!

This amp looks like a real "hummer"!

 

[Tomo]

Hey,

I am not talking about the PSU. I am talking about amp.

Who says you must build the author's PSU? I rarely do in real life. I design my own version depending on what I have at hand. Besides it would be so easy to implement DC filament supply and High V supply at the grade "WE" consider standard.

Ya acting silly ol' man. I ain't a noob.

T

 

[jeffreyj]

Where did you say you weren't talking about the PSU?? I missed that part.

Surely you jest about building your own power supply?! Making 6.3V at up to a couple of amps is a task best left to professionals, Tomo, and methinks you don't come close to qualifying!

Seriously, though... what I liked about the amplifier circuit was putting 4 triodes in parallel. I think the big problem with tube amps can be summed up in one word: output transformer. Okay, two words. Anyway, it occurred to me that with 4 tubes in parallel, the anode impedance ought to be low enough to drive headphones directly (well, through a DC blocking capacitor, anyway... hmmm.. a high voltage/high-capacitance/non-electrolytic capacitor would be required... that output transformer ain't lookin' so bad after all?!)

I don't like R105, either. It's begging to be replaced with a current source. This is one place where adding a transistor or two definitely helps, no matter the topology.

That PSU is shaky, though. Big time shaky. Hell, the filament voltages don't even match up! Gotta wonder if so little attention was paid to the PSU, what does it say about the rest of the amp???

 

[Tomo]

Umm ...

Some dude is using it for a pair of hones. I think it works fine. Yeah even with the shaking PSU.

But then if I were to build this thing, I probably use PSU that I can stomach.

However, I suggested this site because of the amp design and not because of PSU. (There are site for that too, but not this particular one.)

T

 

[zzz]

Quote:

Originally posted by jeffreyj Hey Tomo, I thought Morgan Jones pretty well thrashed the use of AC for the filaments, especially in the case of directly heated triodes?! This amp looks like a real "hummer"!

none of these tubes is directly heated, and even if some were, direct heated triodes don't really care about differential noise on the cathode. so far I've always used ac on the filaments, and the only time I had any hum issues was when my transformers sagged under the load and starved the filaments.