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Old 31st May 2004, 12:11 PM   #1
sonix is offline sonix  Germany
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Question balanced input stage

hi,
i need a balanced input stage, like this:
Click the image to open in full size. , for a 300b se amp like this:
Click the image to open in full size..
is this possible?
thanks
sonix
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Old 31st May 2004, 05:32 PM   #2
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What's your goal? Do you just want a balanced input or do you want additional voltage gain as well? If you just want a balanced input and don't need any additional voltage gain, why not use a good quality input transformer?

se
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Old 31st May 2004, 05:43 PM   #3
sonix is offline sonix  Germany
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i would like to have an ballanced input. examples of one input transformer?
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Old 31st May 2004, 06:04 PM   #4
jam is offline jam  United States
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Default Why not use an input transformer....

That's our Steve.............
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Old 31st May 2004, 06:14 PM   #5
SY is offline SY  United States
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Default Re: Why not use an input transformer....

Quote:
Originally posted by jam
That's our Steve.............
Somehow, one of those migrated to the input of my amp, too.
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Old 31st May 2004, 06:35 PM   #6
jam is offline jam  United States
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SY,

I am waiting for Steve to come up with the self powered transformer only amplifier..............

But kidding aside what transformer are you using and have you tried to use a transformer as a phase inverter to bridge an amplifier.

Regards,
Jam
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Old 31st May 2004, 06:38 PM   #7
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WTF, that first schematic has an unbalanced input...but no way to balance the signal when using it... omgHUH?? Anyways, yes an input transformer will work. You can build a differential amp to balun the signal before feeding the power amp. You could redesign it to be balanced all up to the output tube.

Tim
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Old 31st May 2004, 06:50 PM   #8
sonix is offline sonix  Germany
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thanks for all answers!! can anyone do a redesign of the second circuit? PLZ !! I'm a beginner on this field

thanx
sonix
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Old 1st June 2004, 12:58 AM   #9
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Quote:
Originally posted by sonix
thanks for all answers!! can anyone do a redesign of the second circuit? PLZ !! I'm a beginner on this field
Not a problem. Just put the transformer between the input jack and the attenuator like this (note the new value of the attenuator):
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Old 1st June 2004, 05:01 AM   #10
SY is offline SY  United States
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Quote:
Originally posted by jam



...what transformer are you using and have you tried to use a transformer as a phase inverter to bridge an amplifier.

Regards,
Jam
JT11-P1 and yes. I posted a schematic of my input stage a few months back. I'm quite happy with the result.
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