Here's a question that came to mind with the "Build a Bass Amp"
thread.

If Marshall or Fender used the oddball tubes that Ampeg used in their
amps, would they be so difficult to find. Tubes like the 7199, 7027,
12DW7, 6146B, etc. I know you can still find these, but they don't
seem as common as 12A?7, 6L6, 6550, EL34, etc. Any have any ideas on
this?

On Sun, 27 Feb 2005 15:13:17 +1100, Greg
wrote:

Here's a question that came to mind with the "Build a Bass Amp"
thread.

If Marshall or Fender used the oddball tubes that Ampeg used in their
amps, would they be so difficult to find. Tubes like the 7199, 7027,
12DW7, 6146B, etc. I know you can still find these, but they don't
seem as common as 12A?7, 6L6, 6550, EL34, etc. Any have any ideas on
this?

Tubes common in 1968 aren't now. Only tubes usable in geetar amps
will be available in a few years. Get 'em while they're hot.

And just a note about "quality": when the US military wanted the best
cost-no-object, people's-lives-depended-on-it quality tubes (and,
incidently, other complex objects) they found that the best results
were from selecting from mass-production lines.

IOW, sometimes the best (*to be defined*) quality can come from
an experienced production line and an appropriately winnowing QC.

To express the contrary, widgets *not* made on an experienced
production line vary from design center more, pretty much by
definition.

Does this mean that anybody is making 12AX7's like Telefunken or
Amperex did in their production highlight? Maybe. Does it imply that
it's no longer possible? I just don't know.

Chris Hornbeck

Chris Hornbeck wrote:

On Sun, 27 Feb 2005 15:13:17 +1100, Greg
wrote:


Here's a question that came to mind with the "Build a Bass Amp"
thread.

If Marshall or Fender used the oddball tubes that Ampeg used in their
amps, would they be so difficult to find. Tubes like the 7199, 7027,
12DW7, 6146B, etc. I know you can still find these, but they don't
seem as common as 12A?7, 6L6, 6550, EL34, etc. Any have any ideas on
this?


Tubes common in 1968 aren't now. Only tubes usable in geetar amps
will be available in a few years. Get 'em while they're hot.

And just a note about "quality": when the US military wanted the best
cost-no-object, people's-lives-depended-on-it quality tubes (and,
incidently, other complex objects) they found that the best results
were from selecting from mass-production lines.

Sometimes what the military needed in a tube may not be
the same thing audiophiles want. The mil application
might call for extreme ruggedness but noise not an
issue like it would be for a phono preamp.

Also, it's been said that tubes that were made for the
military in the 80's may not be that good. These were
meant for replacement use in older equipment the military
hadn't obsolete yet. Or equipment serving non critical
secondary purposes (similar to that beat up old radio
you have in the workshop or the garage). Much of these
tubes bought as spares would sit around in warehouses,
and only a few got pulled for repair replacements.
Even if 3/4 of the spares were no good the repair guy
would just get another until he got a good one, and toss
the NOS bad ones. Even if they did get sent back to the
manufacturer as defective (assuming someone went to all
the trouble of doing that vs just throwing them out) the
manufacturer would make good with replacements or cash
refund. But most of the bad ones would never see the
light of day before the "warranty" was out anyway.
So don't pay extra for "mil spec".

The phone company was the really demanding customer, not (for the most
part) the military. The military did have a few super critical uses but
sometimes they met the need through special tube requests for changes
to an existing design, sometimes they just upselected existing stocks,
and in a couple cases I am convinced they built a tube on a covert
basis whose very existence is still secret. It's doubtful you'd find it
any better though.

The telco's most demanding app was the undersea cable with repeaters
that had to last twenty years and were unserviceable (unless you
pulled the cable up.) There were two types built for this very service.
They had no other app and are big plums for collectors today.