filaments above chassis

[funkmeblue]

I've seen this done on a roccaforte ultra 50 amp (a prototype). Seems like this would virtually eliminate any interaction from the ac heaters. No need to twist them. Useful for octal pre or just tight places where lead dress can become a problem. Anyone ever use sheilded wire for the heaters? http://www.roccaforteamps.com/ultra-50.html

[Firestorm]

I'm not sure what you mean by "this" ...

[M Fowler]

I haven't seen filaments wired on the top of the chassis like that. Soldano's are wired straight not twisted. But some builders may be running DC filament.

[Structo]

That's new to me as well.

I can imagine the chassis shields the tubes from the AC.

I wonder if he came up with that idea?

I've seen guys run transformer and choke leads above the chassis but not heaters.

[M Fowler]

Yeah I have seen the PT and OT leads above the chassis as well and did that to my Ceriatone Express to quiet things down a bit.

Not sure what the advantage to doing it that way would be all one has to do is go all DC supply or elevated a DC voltage above the AC voltage.

[Andy Le Blanc]

That "looks" cool, is it for cloud busting?

why all the extra work, is it really worth it?

[Phil_S]

...why all the extra work, is it really worth it?

My sentiments exactly.
I'd suggest, if you've got noise, deal with it. Chances are, if you follow accepted lead dress, you''l be fine. Are you looking for a solution to a problem that doesn't exist? Also, I really don't like the idea of wires on the outside.

[azatplayer]

Looks clean inside tho.

[Colossal]

Shielding might be improved to some degree, but I think exposed wiring on top of the chassis is an added liability to the consumer and as well as an opportunity for an increase in probability of failure at some future point. Consider the mechanical strength of the traditionally tightly twisted filament wires versus separated wires connected only at pins 4/5 and 9 on the top of the chassis. Further, if noise is such a big deal as to warrant a novel approach, I'd install a highly regulated DC source and run the heaters that way. Just my $0.02 however. Beautiful looking amp otherwise.

[TheHandsomeOrk]

Is it really needed. I like to keep all wiring inside the faraday cage.

[Cliff Schecht]

I think it's a fantastic idea. He's using the chassis as a shield against the more sensitive internal electronics. The bottoms of the tubes are shielded by the tube sockets and any stray fields will be blocked by the large steel chassis (looks steel, not aluminum). The exposed wire won't be a problem once the head is in a cabinet..

[Dai H.]

I saw this and thought it was a cool idea also:

http://forum.marstran.com/viewtopic.php?f=5&t=261

apparently though, not really a new idea:

http://ax84.com/bbs/index.php?id=405597

[flood]

dunno about effectiveness (i'm beginning to use DC heaters for anything with OTT gain) but i have to say... that is one of the cleanest, nicest, most admirable builds i've ever seen.

i think the finest build i've seen was one on this forum; something called the highway wreck.

slightly OT question: is it possible to get those 90 degree/perfectly straight leads WITHOUT prebond wire? you don't get prebond in india....

[Andy Le Blanc]

aluminum chassis? hows that vs. mild steel at magnetic shielding?

[Dai H.]

slightly OT question: is it possible to get those 90 degree/perfectly straight leads WITHOUT prebond wire? you don't get prebond in india....

doesn't look quite perfect (in terms of a 90 deg. angle). I bet you could just bend them with pliers to be like that (Hiwatts are such).