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it seems to get the right amount of gain with the SG / T-Tops volume on 8 or 9 and with teh amp bright channel treble and presence on 3 . it sounds really good, i don't understand why i don't get that spitty noise, i thought they all needed that mod ! i won't complain though ! LOL great amp , i'm su...

i have a 78' 2 input DR504 that is stock except i replaced all teh electrolytic capacitors and installed teh M Huss bias mod. i have seen teh "Spitty" Mod on that website but i don't have the feeling mine has that problem, especialy when i hear the "before" clip of teh normal cha...

after i tried with the 110k instead of the 82k, i had IK=5ma , so as i thought i had a problem in my resistors ! so i checked teh trimmer and realised despite i was sure i had measured it ok, it was not mounted right ! LOL so once it's been mounted correctly, i could finally setup the bias. i have n...

my bias trimmer has two feet (not 3) , it's not the stand tall model but the one lying (the one sold as jtm45 bias trimmer kit on metroamp). one end goes to ground and the other goes to the 15k resistor. when measured each side of the trimmer / 15k resistor combination, it was going from 15k to 39k ...

i have one side of teh 25k trimmer connected to a turret that goes to ground , the other side of teh trimmer is connected to teh 15k . i measure -39vdc between the trimmer and the 15k resistor. on teh other side of teh 15 k resistor i have -65vdc. i only used one 25k trimmer (between ground and the ...

i tried the Mhuss bias circuit mod except i used the UF5408 diode and two 2w resistors in serie to make the 82k but i when i use a bias tool , IK = 0 with or without power tubes installed (and my plate voltage seems to be higher as i now measure 500 vdc for 220 ac in whereas i think i measured a sma...

i saw that Aspen Pittman says it's possible to put a 1N4007 diode instead of the BXY94 in his amp book and i found some 1N4007 diodes in my stock of parts (although they look much smaller than the ones i have actualy but i wonder if there are some 1N4007 made for different voltages / A , although it...

i have a 78' DR504 2 inputs with tag board and i'd like to convert the bias circuit. i saw the M Huss mod but don't have some UF1007 diode (couldn't find some here) , so as i have some UF5408 and saw a 2001' hiwatt DR504 schematic where it was used in place of the UF1007, i was wondering if i could ...