On Tuesday 05 November 2002 17:57, Steve Harris wrote:
On Tue, Nov 05, 2002 at 08:26:40 +0100, Tim Goetze
wrote:
> Steve Harris wrote:
> >The bad news is that it means going inside someones amp with a probe, I
> >would have a go myself, but I've allready killed my last amp, and my
> >electronics skills are bad enough that I would probably fry myself ;)
> looking at a fender tube amp schematic shows +140
V after the first
> 12AY7 -- i don't have any equipment that would make this signal
> digestable by a computer.
Yeah, ggjjjzap. I dont have anything that can handle
that either. How do
those attenuating osciloscope probes work? Maybe you can build something
equivalent in an audio lead, though I wouldnt be happy putting anything
like that through a homemade attenuator into my desk.
I have one of these:
http://www.velleman.be/Product.asp?lan=1&id=338488 (Velleman PCS64i digital
oscilliscope adapter for PC). It's good to 600V, I think. It attaches to
your parallel port. RadioShack carries them in the US. They run about $300.
As it also works as a transient recorder and spectrum analyzer (to 32MHz), it
is a great buy. Even though it is an 8-bit device, it is useful in showing
what the signal looks like, as your eye can't distinguish the difference on a
75dpi screen between 16 bit and 8 bit samples.
If you were close enough, I'd let you borrow my Tektronix 475 analog
oscope.... With a 10x attenuator probe it's good for signal amplitudes of a
couple hundred volts with a DC offset of 600V.
If I had the amp in question here, I would be happy to do the trace for you; I
routinely work on hot tube gear. (I'm a broadcast engineer; broadcast
transmitters that are tube output have 10kV or more floating around them.)
--
Lamar Owen
WGCR Internet Radio
1 Peter 4:11