Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TonyM on June 18, 2024, 07:21:14 pm
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Hi All,
I have a Marshall JCM 800 slp mkII 100W clone I built with the help of a tech guy 30 years ago.
This amp has to some degree been modelled around a JCM 900 which includes a large resistor for filtering.
Back then I chose to put in the JCM 900 Dagnall PT & OT and have decided I want to put in filter choke. The PT is a Dagnall TXMA 00021 100W but I'm having trouble finding a datasheet with specs so at match the choke.
There have been recommendations on other forums for a Hammond 5H@120ma but I'm leaning towards 5H@200ma 68ohms from other research and deduction.
So I'm thinking the spec sheet will help workout which choke would be better suited.
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If the CLC filter is between the plate supply node and screen supply node, 120mA will be sufficient (because it’s only seeing screen and preamp* current. *i.e., including PI)
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So I'm thinking the spec sheet will help workout which choke would be better suited.
The PT spec sheet won't help. The schematic is better. Since the choke does not have to carry the plate current I'd go with the Hammond 194F (https://www.hammfg.com/files/parts/pdf/194F.pdf?v=1697661947) that Hammond suggests for a JCM 800 100W amp.