Broskie "Unbalancer" - transformer specifications - diyAudio
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Old 5th January 2012, 09:38 PM   #1
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Default Broskie "Unbalancer" - transformer specifications

I'm currently in the process of soldering Broskie's "Unbalancer" PCB:

On pages 13 and 18 he specifies what sort of secondaries are required for the transformers, however I am a little confused as to how I need to specify the windings to the transformer manufacturer (it is an r-core type).

The input tubes I am using are 5963 tubes, whilst the output tubes are 5965. Hence in both cases the closest recommendation as per the chart on page 13 of the manual is the 12AU7 - with a B+ of 240V. And an AC secondary of 330VAC. However on another page he specifies the following:

The power supplies require an external power transformer(s) with two secondary windings (120Vac to 260Vac and 6.3Vac to 12.6Vac).
Presumably he is assuming that the 330VAC is centre tapped?

The r-core manufacturer has asked for a specification in the following format:


240VAC input

60 - 0 / 60 - 0 each 150ma = 300ma

6.3 - 0 / 6.3 - 0 each 1.5A = 3A

For the Unbalancer using 12.6v filament tubes - would this be the correct voltage specification?

240VAC input


330 - 0, 1 Amp (200mA for each tube)
12.6 - 0, 4 Amps (say, 1 amp per filament)
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Old 5th January 2012, 10:24 PM   #2
Zibi is offline Zibi  Poland
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Join Date: Jan 2006
Location: Bialystok
Correct, but for 100W guitar amplifier:
Hammond Power Transformer 290HX
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Old 6th January 2012, 12:00 AM   #3
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The Hammond looks good but may be overkill.

A custom wound r-core is probably about half the price and hopefully with those specifications will supply enough juice!
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Old 6th January 2012, 10:05 AM   #4
Zibi is offline Zibi  Poland
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Location: Bialystok
You don't need 400W power transformer!!!!!
Buffalo III DAC Tube Output Stage

Last edited by Zibi; 6th January 2012 at 10:23 AM.
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