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RE: GRAAF GM 200

Hello to Mark S Allen and all.
I must ask your comprehention and tolerance with my english. It is not my mother language.
I read with much interest your long explanation on tuning up the Graaf 200 OTL.
I have one too. But the matching procedure is very long and very time consuming. I already did Graaf method but I can´t match well.
I was working with 65mA on Bias, but now have lowered a little bit further to 50m, just for precaution.
I have an Hickock 600 tube tester that tests the 27GB5 /PL504.
Most of the spare valves I have reads between 4000 & 5000 and try organise them like that in the amp, but when I try Graaf matching procedure direct in the amplifier ( those 15,5 & 17,5mV) everything get wrong. Is just like this proceedure contradicts the Hickock.
Most of the 4000 valves read 19-20mV and some 5000 reads 8~10mV. It crazy, and I don´t understand why.
Can you help Mark? It seems you have a lot of experience in this amp. I have other OTL amps that sounds much better. Perhaps I am doing something wrong. My speakers are Quad ELS 57 and YAMAHA NS1000M.


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