Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: frpax on April 23, 2017, 08:13:35 pm
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I did a search for this, but I wasn't getting all the info that I wanted. So questions:
1. I want to add a Master Volume to the Hoffman 5F6A circuit, similar to the MV on the Plexi 6V6 (I realize that they are 2 different circuits, hence the help needed). If someone can draw this out in "layout" form for me, I would greatly appreciate it.
2. There is no real "need" to ground the buss wire that goes across the back of the pots, as the layout shows; the pot contact with the chassis is sufficient for that. Correct?
3. Am I correct in that the 2nd instrument input & the 2nd Volume pot (both from the left) is the "Bright" channel?
4. When you go from the lamp to "the heaters", do those leads go to the places on the circuit board (as indicated) AND to the tubes? I'm assuming some sort of "daisy chain" fashion is what I'd do. Please advise. I figured this out. Nevermind!! :think1:
That's all I can think of, for the moment.
Any and all suggestions are both greatly appreciated and encouraged!
Thanks,
Frank
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1. I want to add a Master Volume to the Hoffman 5F6A circuit, similar to the MV on the Plexi 6V6 (I realize that they are 2 different circuits, hence the help needed). If someone can draw this out in "layout" form for me, I would greatly appreciate it.
They are NOT that different & are very similar, so study the schematics and layouts of each and you should be able to easily figure this out. :icon_biggrin: :thumbsup:
http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf (http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf)
There is no real "need" to ground the buss wire that goes across the back of the pots, as the layout shows; the pot contact with the chassis is sufficient for that. Correct
Hoffman's Library of Information answers your question about the buss wire. That library is a wealth of great information!
http://el34world.com/charts/grounds.htm (http://el34world.com/charts/grounds.htm)
With respect, Tubenit
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Look at the 5F6A layout. There is a violet wire that connects the Treble wiper to the board. Cut that wire in half. Connect the violet wire that's attached to the treble pot to the left lug of your new MV pot. Connect the violet wire that's attached to the board to the wiper of your new MV pot. Connect the MV pot right lug to ground.
You are correct about the bright channel.
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Look at the 5F6A layout. There is a violet wire that connects the Treble wiper to the board. Cut that wire in half. Connect the violet wire that's attached to the treble pot to the left lug of your new MV pot. Connect the violet wire that's attached to the board to the wiper of your new MV pot. Connect the MV pot right lug to ground.
You are correct about the bright channel.
Like this?
(http://img.photobucket.com/albums/v376/fpaxton/MV5F6A_zpsbvwjxo0o.jpg)
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yes
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yes
Excellent!