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RE: GRAAF GM 200

I have a copy of the entire manual on my home computer, I'm away on
business for a few more weeks, but I can send it thru e- mail when I
return.
About the tube matching, from my personal experience I use an amplitrex
tester to test all tubes for plate and mutual conductance, just last year I
tested 50 6lf6's for my futtermans, they use 6 per amp, I ended up with 7
matched sets from the 50 tubes, 8 tubes were either too high or too low to
fit in to the sets.
I installed the worst of the sets into a pair of amps, aligned set bias and
balance and let them work together for 200 hours before I listened to music
or turned them off, that's 8 days. I then listened to them for a few months
about another 200 hours then retested the tubes, they were matched to
within 1 milliamp of each other when retested, much tighter than when I put
them into the amps.
The way the tubes work together in circuit seems to dial them in tighter
just by being in circuit.
Therefore I feel 80 tubes for the Graaf should yield 2 complete tightly
matched sets for the amp. 32+32.

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