wrote in message
oups.com...
A quote from "Diamonds are a Girl's Best Friend",i.e. a little humor,
as opposed to a strawman.

Offhand I can't think of an obso semi because

**I accept your admission that you cannot provide an example. I figured you
could not. I can supply literally dozens of examples of obsolete tubes.
Here's another:

A few years ago, I serviced an ARC power amp. I can't recall the model
number. It required a new set of output tubes. I fitted some US made NOS
6550 tubes. I was then unable to pull the amp into the correct range of bias
(it uses LEDs to indicate correct bias current). A 'phone call to the local
distributors and I was able to (un)happily inform my client that the repair
bill had just gine up by AUS$1,000.00, since I had to fit a mod to the amp,
so it could cope with a 6550, other than a Sylvania branded one. YIKES! The
list goes on. I promise you that obsolete semis ARE a problem, but mostly
with mid-fi equipment. VERY rarely with decent equipment, which uses
descrete output stages. Tube equipment, OTOH, is a whole 'nuther ball game.
As all those fools who spent big bucks on those silly Musical Fidelity
hybrid products will surely discover.

I am primarily a
homebrewer and usually if a solid state project doesn't have readily
available parts I don't start in the first place. They are definitely
out there though. Usually it's an IC for which there is a similar part,
but it doesn't match the PCB layout at all.

**Example please.

You wind up building a
kluge board. I have worked on solid state home organs where the
generator IC is NLA, but a third party has a prefab module (potted of
course) that replaces it. The organ in question also had a dead solid
state power amp but we took it and the speaker out and put in a line
level out. The owner then just used a commodity keyboard/bass combo
amp, with complete satisfaction.

**Hang on a sec! We're discussing audio amplification equipment, not musical
instruments.

What kind of tube was it your three watt push pull amp used?

**Buggered if I can recall. The whole job was a nightmare. I'd rather forget
about it. I can go through my records and find out, if you really don't
believe me.


--
Trevor Wilson
www.rageaudio.com.au