Tube Amps / Music Electronics
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|4/18/2005 11:28 AM|
a friend recently gave me the chassis out of a redbear MKX50. it was missing the tubes, but otherwise looks ok. I found the schematic at blueguitar and saw that it's very similar ( but not identical )to a marshall 2204 only it uses some russian preamptubes that has the heaters wired differently and it uses 5881. I rewired the preampsockets to take ECC83 and changed the screengrid resistors to 1K/5w and isntalled EL34 ( I dont have any 5881 nearby..)rewired the P.I./feedbacknetwork and fired it up.
it sound quite good, but not quite there..
so here is the problem. the voltage sits at roughly 470Volt on the EL34 anodes and doesnt sag too much when pushed, I've compensated the output transformer by puting the secondary impedance on 16ohm when running into 8ohm but the amp just wount give me more than about 30watts ( its supposed to be 50w )and when pushed the sound is a little "spoungy" and undifined. I realize it might just be sheap transformers, but does anybody have any other idea?...
thankfull for any help..
|Rick Erickson Are both pins 1 and 8 grounded on t... -- 4/18/2005 12:38 PM|
johan ok...feel a little stupid now...