Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: acheld on May 02, 2021, 09:49:48 pm
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I am planning a Bassman style build using GZ34, 5881's, and 12AX7, 12AY7. Essentially Dougs 5F6A but with 5881 tubes instead of the 6L6, which of course are similar. This amp will be used daily but not driven hard due to my old ears, wish to remain married, and tender sensibilities. I play primarily single note jazz, with ham fists.
Looking at Hammond's catalog is confusing, or maybe the better word is overwhelming.
It appears the OT should be the 1760K with primary winding of 4K ohms, into 2,4 and 8 ohm secondary. Does that seem correct?
Which power transformer to use? I'd like to avoid excessive voltage if possible -- my wall voltage is 125V routinely. What plate voltage for the 5881's should I be aiming for? (No experience with this tube other than hearing it play. . .)
It looks like the 290DX should be about right. Thoughts?
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yes to both transformers.
fender 5F6-A specified 5881 output tubes.
current production russian 6P3S-E are close match. the coin base type seem to be the most dependable.
https://el34world.com/charts/Schematics/files/Fender/Fender_bassman_5f6a_schem.gif
--pete
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It appears the OT should be the 1760K with primary winding of 4K ohms, into 2,4 and 8 ohm secondary.
4k Primary for 2 x 6L6GC in p-p
The original 5881s were specd at 23W. 6P3Se (coin base) are close at 20.5W and are very reliable at mid-400s voltages. I’ve put them in a range of 6L6 amps, including Fender 59 Bassman RI and RI LTD amps with no problems (but have removed the retainer clips in those amps to use these tubes).
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Dummy and tubeswell, much appreciated. I'll take a look at those 6P3SE tubes. I'm all about reliability these days.