Subject: Re: [linux-audio-dev] [ann] unmatched - a LADSPA amp tone
From: Paul Winkler (pw_lists_AT_slinkp.com)
Date: Thu Oct 24 2002 - 20:40:14 EEST
On Thu, Oct 24, 2002 at 05:31:04PM +0100, Steve Harris wrote:
> On Thu, Oct 24, 2002 at 08:23:32 -0700, Paul Winkler wrote:
> > On Thu, Oct 24, 2002 at 08:41:36AM +0100, Steve Harris wrote:
> > > Looking at the scope traces from that guys site (which I will read later
> > > today), there is some fairly serious HP filtering going on sometime after
> > > one of the amp stages.
> >
> > Output transformer? Certainly they don't have infinite response...
> > It's not clear to me where and how those scope shots were taken.
>
> Could be. Aparently there is often HP filters insode amps to strop the low
> freqs dominating though.
I'm looking at a schematic for an 18-watt marshall at the moment...
there's a cap between the input gain tube and ground which *might*
be a HPF, but I don't really grok tube circuits well enough to be sure.
> Some of the scope traces are annotated with where they were taken from but
> its all greek to me.
On the 18watter page, they only say whether a resistive or speaker
load was used. From that, I now suspect the scope was looking at
the voltage across the load.
BTW, the 18watter page has sound samples here:
http://www.ax84.com/pdr/18watter.html
it's a nice little amp. the mp3s have nasty mp3 artifacts,
and it sounds kinda nasal like he miked it oddly or used an odd cabinet,
but the bridge pickup sample sounds kinda like AC-DC.
Now THAT's a classic rock tone.
--Paul Winkler http://www.slinkp.com "Welcome to Muppet Labs, where the future is made - today!"
This archive was generated by hypermail 2b28 : Thu Oct 24 2002 - 20:44:18 EEST