DIYbanter - View Single Post - What's the latest in Desoldering gadgets?

Michael Black[_2_]

On Sat, 25 Feb 2017, wrote:

On Fri, 24 Feb 2017 16:11:20 -0600, Jon Elson wrote:

wrote:

On Tue, 21 Feb 2017 12:33:12 -0500, Neon John wrote:

The Woofers are 80 inches each....
Handle 5000 watts per channel.

Heck, that would involve a power amp with around 200 6L6 or 807 tubes in
Push-Pull Parallel-Parallel-Parallel-Parallel etc... For EACH
channel...... (And an output transformer about 3 foot big, weighing
close to the weight of a Harley motor cycle, and costing 10X the price
for a brand new Harley).....

No, certainly not! You use the modulator from an old AM broadcast
transmitter. I was at a Grateful Dead concert in 1969 and they wheeled out
this THING on the stage with big glass globes, and when they lit up I
realized they were TUBES (valves to the British)! Not sure of the type, but
at least several thousand Watts. I borrowed a set of ear muffs and sat back
for a show!

Jon

I was at several Grateful Dead concerts in the late 60's and afterwards.
I never saw any such thing. Are you sure you were not "tripping"? That
may have just been a common 6L6 tube in a guitar amp, and your
hallucinations made it look really BIG....

They went through various iterations, and sound people. SOmeone got
hooked in at one point, maybe it was Bob Heil but maybe it was the
soundman for Quicksilver Messenger Service (who was also a ham), there was
s story of someone having an Electrovoice "Voice of the Theatre" or
whatever it was adapting that. Owsley was involved, leading to the Wall
of SOund, which almost as soon as they finally got it going right, they
abandoned. They were using McIntosh amplifiers for a while, there's a
story, maybe about Woodstock, where they blew them out and had to hurry to
find replacements, finding a "close" dealership and getting them to open
up on a Sunday or something.

Things were evolving, and bands like the Dead helped that developemnt. So
they went to that Wall of SOund to adapt to the much bigger venues, then
dropped it because it was too much trouble to move, but I thought the work
helped other things to develop. So they may have been using just about
anything at some point, including home built equipment.

If you paralleled enough tubes, the output impedance would go down, so no
matching transformer for 8ohm speakers. I'm not sure if that was ever
done with audio, but I have seen it done with radio amplifiers, a bunch of
tubes in parallel so the output impedance is 50 ohms to match the coax.

Michael