Advice sought on thermionic headphone amp

[jcx]

I quickly put down a pair of bamboo headcup ES headphones at a audio show when I could easlily feel the leakage current

but line powered dynamic heaphone tube amps can safety earth the xfmr output side and then should be quite safe

 

[Simon B]

...line powered...

Never easy sorting that with "amphibious" equipment though.

 

[marce]

Most enjoyable thread, about the only laugh I've had in Barrow this week, you could say I submersided myself in reading the banter posted herin...
Cheers

 

[Simon B]

Hi Marce,

I'm not going to enquire too closely about what you're doing in Barrow, but please don't let any passing Ministry of Defence bods pick up on this as a new procurement initiative. I think we know what could happen.

 

[PlasticIsGood]

the wires are much clooser to you with headphones, I have yet to see a audio output xfmr claim "double insulated" construction

while as long as the headphone insulation/air space is fine you won't have problems - there is little question that the safety story is less compelling with heaphones powered from lethal supply V on your head vs the same powering speakers 10 ft away from your listening position

OTOH, speakers have exposed connections designed for your thumbs. You might even try to tighten them both at once. That's why speakers, and headphone leads, should always be grounded, and the amp should be appropriately fused.

 

[PlasticIsGood]

Of the OTL I understand. Of the SET I do not.

Same point, more or less, taken a little further. I don't thing OTLs have ever been legitimate, BTW.

Apart from the adoption of some SS ancilliary circuits, it seems that a great deal of the effort devoted to valve amps post-RDH4 has been to cope with modern recordings, sources, and speakers. This largely boils down to reducing output impedance, which in turn translates to a struggle to reduce OPT winding ratio.

The relatively high impedance of headphones allow a reasonable turns ratio, just about, and low bass is possible without losing the top end.

 

[Simon B]

Speakers might be safer I suppose, but I've never heard a mylar cone drive unit sound anything but awful.