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Post subject: a 59' Bassman re-issue
Posted: Fri May 28, 2010 3:17 pm
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Ok, this is a 59' Bassman Re-issue, one of the earlier 90's models, not the LTD. So, when installing new power tubes, there appears to be no bias control pot. What was Fender thinking? I know the LTD version do have an internal bias control, but the first versions do not. So, how to bias this sucker? It appears one needs to go through a whole rigamarole to do this by changing the resistor, if needed. But what I'm hoping to do is use a 5U4G tube rectifier ( which should lower the plate voltage ) and put in some Tung-Sol 5881's. These are reportedly safe to run up to 400 volts on the plates. Then check the mA and the plate voltage with my Bias Rite. If the voltage is around 400 or less, and the mA measures about 45, I should be good to go, yes? What I'm trying to do is get more sag and less volume from the amp, to use as a Harp amp. I will be replacing the 12AX7 pre-amp tubes with some lower gain tubes in V1 and V3, as recommended by many players using this amp for harp. Anyone got any other tips outside of sending it to a tech for a bias control to be installed?


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Post subject: Early reissue bassman bias issue
Posted: Fri Jun 11, 2010 10:43 pm
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Joined: Thu Jul 19, 2007 4:25 pm
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Location: Missouri
Hey man, don't make it too hard. I just picked up one of these, a '93 and it had a solid state rectifier and some old original chinese 6L6's and 12AX7's that I replaced. I got the Winged C power tubes and Tun-sol 12aX7s. Sounds great. I did a bit of research and when you buy your 6l6s, request them in the medium range so they will fit with the fixed bias in the amp. I would love to put a bias pot in the amp, and it can be done, but I think I'll hold of as the amp sounds great the way it is. I hope that this helps.

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Posted: Sat Jun 12, 2010 3:41 am
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Hello,

Visit: http://tone-lizard.com/Bassman_Modifications.htm


Tissan :wink:

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