balanced input stage

sonix · 31st May 2004, 12:11 PM

hi,
i need a balanced input stage, like this:

, for a 300b se amp like this:

.
is this possible?
thanks
sonix

Steve Eddy · 31st May 2004, 05:32 PM

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

sonix · 31st May 2004, 05:43 PM

i would like to have an ballanced input. examples of one input transformer?

jam · 31st May 2004, 06:04 PM

That's our Steve.............

SY · 31st May 2004, 06:14 PM

Quote:

Originally posted by jam
That's our Steve.............

Somehow, one of those migrated to the input of my amp, too.

jam · 31st May 2004, 06:35 PM

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

Sch3mat1c · 31st May 2004, 06:38 PM

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

sonix · 31st May 2004, 06:50 PM

thanks for all answers!! can anyone do a redesign of the second circuit? PLZ !!

I'm a beginner on this field

thanx
sonix

Steve Eddy · 1st June 2004, 12:58 AM

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):

SY · 1st June 2004, 05:01 AM

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.

31st May 2004, 12:11 PM	#1
sonix diyAudio Member Join Date: May 2004	balanced input stage hi, i need a balanced input stage, like this: , for a 300b se amp like this: . is this possible? thanks sonix

31st May 2004, 06:38 PM	#7
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	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 __________________ Seven Transistor Labs Projects and Resources

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31st May 2004, 05:32 PM	#2
Steve Eddy diyAudio Member Join Date: Sep 2002 Location: Sacramento, CA	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

31st May 2004, 05:43 PM	#3
sonix diyAudio Member Join Date: May 2004	i would like to have an ballanced input. examples of one input transformer?

31st May 2004, 06:35 PM	#6
jam diyAudio Member Join Date: May 2001 Location: Charlotte,NC,USA	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

31st May 2004, 06:50 PM	#8
sonix diyAudio Member Join Date: May 2004	thanks for all answers!! can anyone do a redesign of the second circuit? PLZ !! I'm a beginner on this field thanx sonix