Re: Tube amp with 2.5 Ohm speakers??

On Mar 19, 8:59=A0pm, John Byrns <byr...@[EMAIL PROTECTED]
> wrote:
> In article <PPcEj.312846$7Q7.304...@[EMAIL PROTECTED]
>,
> =A0"Iain Churches" <Iai...@[EMAIL PROTECTED]
> wrote:
>
> > I have been asked about using a tube amp with
> > low impedance speakers (2.5 Ohms)
>
> This doesn't seem like a big deal if you are specifying the output
> transformer. =A0Is the questioner asking what to do with an existing
> amplifier that doesn't include an output transformer with a 2.5 Ohm
> secondary configuration option?
>
> > Does anyone have experience with this kind
> > of setup?
>
> No, sorry.
>
> > First thoughts are that with PPP in triode
> > mode one could probably achieve a DF of 10.
>
> I don't understand what SE vs. PP vs. PPP has to do with the DF? =A0
> Assuming you are talking about ZNFB amplifiers, I always thought the DF
> was determined by the plate resistance of the tubes being used along
> with the turns ratio of the output transformer? =A0All other things
being
> equal I wouldn't think PPP would provide a DF any different than plain
> old PP, or even SE for that matter.

Well, you might not find a transformer with precisely the PPP primary
ratio to match whatever you would have used for PP. Some of us might
even sacrifice some of the greater power to up the primary to plate
multiple for greater silence. I have a Velleman K4000 PPP amp which
was built for the power, and it is just as well that it has 18W in
Class A, because it is a Jekyll and Hyde affair, very sweet until you
attach (very) insensitive speakers and turn up the wick on a 100W of
PPP power, when it suddenly becomes an anti-social rock'n'roller's
amp.

> Regards,
>
> John Byrns
>
> --
> Surf my web pages at, =A0http://fmamradios.com/

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
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