Re: [LAD] simulating analog audio devices part II

thanks for your help! :)

porl

On 20/06/07, Dominique Michel <dominique.michel@email-addr-hidden> wrote:
>
> Le Tue, 19 Jun 2007 20:51:58 +1000,
> "porl sheean" <porl42@email-addr-hidden> a écrit :
>
> > thanks for the links!
> > the ax84 one is really good, pretty much exactly what i was after -
> short
> > and to the point (i don't mind a bit of complex math as long as it is
> > explained why i am doing it :)
> > i've looked through a few old valve books (
> > http://www.pmillett.com/technical_books_online.htm is an awesome site)
> but
> > it was hard to find certain info.
> >
> > i should probably have told you that i am making a guitar amp that i
> want to
> > sound dirty (not heavy metal distortion, but old overdriven blues
> sound). i
> > was only talking about a 4k primary because i'm pretty sure that is what
> the
> > OT that i gutted from my fender hotrod (a bit high rated for this
> project
> > but i can't afford to buy much at the moment). i have tried the same
> tactic
> > with PTs of old amps off ebay (the fender one doesn't have a 5V output
> and i
> > want to use a tube rectifier), but even the small one i realised is
> > 375-0-375 for the primary! i think this is a *little* over what i need,
> so i
> > am going to have to buy a new PT. i can't figure out how the old amp
> used
> > this voltage: it was only a p/p el34 amp (2 output tubes). how would it
> have
> > brought the voltage down enough to not kill the valves? maybe el34s can
> > handle a lot but i didn't think the preamp tubes could.
> >
> > anyway, sorry about how off topic this is. i should probably take my
> > questions elsewhere.
> >
> You can try the diyaudio forum. It is a thread with a lot of links on
> vacuum
> tubes theory:
>
> http://www.diyaudio.com/forums/showthread.php?s=5fc6a5fdf8f4d9101e3f07260bc6c498&threadid=38278
>
> You can find some with amule too. Just search for vacuum, valves or tubes.
>
> About the EL34, 375V for Ua is a very low voltage for such a tube. (You
> can
> find the datasheet from http://www.nj7p.org/Tube.php or with google).
> You can go up to 600 or even 700 V without problem. But you are right when
> you
> said at 375 is too much for the preamp tubes. Only some old japanese
> preamp
> tubes can handle such voltages, and they are very hard to find. The best
> is to
> made a separate and low-noise alimentation for the preamp. A simple R-C
> can be
> enough.
>
> For the tubes, I generally prefer new tubes over old ones. Some new tubes
> are
> even better as the best old ones. The engineers of today know what they
> are
> doing when they manufacture a new tube.
>
> Dominique
>
> > porl
> >
> >
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>

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Received on Wed Jun 20 04:15:04 2007