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you suck
"John Fields" <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:m51g32hqrnu8qhs5je0u0fs1ck4tb2fc56@xxxxxxxxxx
> On Sat, 8 Apr 2006 03:57:55 -0500, "Abstract Dissonance"
> <Abstract.Dissonance@xxxxxxxxxxx> wrote:
>
> >
> >"JeffM" <jeffm_@xxxxxxxxx> wrote in message
> >news:1144480902.366203.317800@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> >I know for guitar amps that [it's] not a good idea
> >>>to have no load on the amp when in use
> >>> Jon (Abstract Dissonance)
> >>
> >> Phil put the last piece in place.
> >> The times I have encountered this,
> >> the (relatively cheap and relatively easy-to-get)
> >> phenolic tube sockets burned up.
> >> Here's a description of what happens:
> >>
http://groups.google.com/group/alt.guitar.amps/browse_frm/thread/42a206e1658
2f0e9/7cfe1b7595b5e36c?q=*-energy-in-this-magnetic-field-has-to-go-somewhere
+Normally-it-would-be-dissipated-by-the-load+output-tubes-or+the-windings-of
-*-transformer+high-flyback-voltage-generated+*-close-*-*-*+no-speaker-conne
cted
> >>
> >> You can see that we're getting farther and farther away
> >> from what the OP is likely to encounter
> >> (direct-coupled semiconductor outputs).
> >>
> >
> >The amp I was using was actually solid state and it blew out the power
> >amps... used tda7294 I think. I replaced them and its worked fine since.
I
> >actually ran the things quite a while without an speaker load before they
> >blew.
> >
> >It would seem to me that impedence matching is a universal law for audio?
>
> ---
> It's not. Solid state audio amplifiers are designed to be voltage
> sources with the capability of driving some maximum current into a
> load.
> ---
>
> >I'm not sure how solid state changes that fact? Is there a buffer that
acts
> >as the output transformer or something like that?
>
> ---
> No. There is an output stage designed to drive the load directly and
> to supply whatever current the load needs, up to some limit.
> ---
>
> >(I think another reason
> >for the output transformer is to remove the dc bias that might exist
also.
> >One could cap-couple the speakers I suppose but still doesn't resolve the
> >issue of power transfer?)
>
> ---
> In higher-power amplifiers the output is driven by an output stage
> connected across a positive supply and a negative supply, with the
> output DC coupled to the load.
>
> There is no issue with respect to power transfer since, as the
> output voltage changes, it supplies whatever current the load
> requires.
>
>
> --
> John Fields
> Professional Circuit Designer
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