Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on December 05, 2021, 10:51:40 am
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Hola amigos,
In order to build a clean boost, I have imagined a stompbox with a 1:2 step up transformer.
I have in stock old preamps from a mccurdy broadcast board with good quality audio transformers. Anybody has done that b4 ?
Thanks
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The usual guitar pickup is already wound as high as it can be without too much treble loss.
Eat your spinach.
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I've used a 1:2 Inter-stage tranny, in circuit it was more like 1:1 after loading.
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What about if I use only one half from the primary winding to make it 1:4 then ? I am not worried much about treble loss since the trannies are from highest quality ( and more, I am 50 percent deaf....)
Thanxx
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hey buddy. In the hour between your first and second posts you could have had your answer and eaten lunch too. :l2:
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A 1:2 transformer will quarter the input impedance.
1:4 will divide it by 16! So 1M is seen by the guitar as 62k.
And the input miller capacitance will be magnified.
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Sluckey, I didn't have lunch I was busy taking care of Linda :laugh:
Ok so my idea is not good impedance wise.
I ll go back to what I m better at, arpeggio workout :icon_biggrin:
Thamx buddies
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might not understand your objective, but dual op amps (tl072 or ne5532 are what i'd use) are cheap as chips and what you'd want for a clean boost
remember, there's no free lunch
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Op amps ? Never. I already have a marvelous12ax7 signal boost somewhere that I use from time to time. I just imagined the step up tranny trick as an easy way to boost up the guitar signal ( since I have many of them ) but I did not know about the impedance issue that would occur.
No free lunch ? Not for me :laugh: