[Scott Dorsey]

Hank wrote:
In article ,
Scott Dorsey wrote:

I have generally designed 70v systems for high quality audio to have a
-3 dB point around 20 Hz, which requires pretty huge transformers. I
strongly recommend the Tannoy transformers (which are actually made by
some company in Canada for them) but the cheap Edcors aren't bad if you
buy their "extended low frequency" series. For background music systems
there's no need to have anything that extreme.

Are those Tannoy transformers wound by Hammond in Ontario?

No. I had to go down and find one of them, but they are made by BEI
(www.bei.net). Hammond's transformers are... kind of deficient.

Hammond's own line is at http://www.hammondmfg.com/117.htm. The top of
their line talks about low frequency cutoff at 50 Hz. at full power.

That's not anything to write home about, but you could do okay IF you
could derate the things. What you want is something with the same input
and output Z but with a much larger core.

I think Mouser now carries the Hammond line. Prices, last I looked, are
not too bad, considering that they're about the only quality house
still winding some of the old-spec stuff for vacuum tube iron.

That's actually a pretty big market these days, though. Lots of small
outfits doing good work, like Sowter. Sowter also makes 70v transformers
with good numbers too, but I have never tried them.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."