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:

http://www.tubecad.com/2011/11/25/Un...er%209-pin.pdf

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:

Example

240VAC input

output
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

outputs

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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Correct, but for 100W guitar amplifier:
Hammond Power Transformer 290HX
http://www.hammondmfg.com/pdf/EDB290HX.pdf
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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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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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Old 27th August 2014, 11:40 AM   #5
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Good!
But the thread you link is invalid so could someone please remind us what transformer should we use for Unbalancer?
And for new Unbalancer version, that no more has PSs on board, what Glassware PSs and what transformers should we use?
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Old 27th August 2014, 01:10 PM   #6
Merlinb is offline Merlinb  United Kingdom
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Anything between 200Vrms to 300Vrms, 50mA, is more than enough. Adjust R12 to suit.

(So you could use 200-0-200 up to 300-0-300, 50mA if you prefer centre-tapped transformers)

Last edited by Merlinb; 27th August 2014 at 01:14 PM.
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Old 28th August 2014, 02:19 AM   #7
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Quote:
Originally Posted by Merlinb View Post
Anything between 200Vrms to 300Vrms, 50mA, is more than enough. Adjust R12 to suit.

(So you could use 200-0-200 up to 300-0-300, 50mA if you prefer centre-tapped transformers)
But i would need a high-V + low-V Glassware's PSU, isn't it? As newer Unbalancers no more include PSs...
Then transformer should have high-V + low-V secs. What voltages then, assuming i will use ECC802 input and 6CG7 output tubes?
If i choose a PS-15 PSU, that has 1x high-V and 2x low-V independent regulators, then i could use both low-V DC sources to power heaters at different voltages? Or i'll have to use just one anyway in 12.6V?
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Old 28th August 2014, 08:21 AM   #8
Merlinb is offline Merlinb  United Kingdom
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You should email John Brokie (Tubecad) with these questions as they are specific to his PCBs.
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Old 28th August 2014, 10:49 AM   #9
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Quote:
Originally Posted by Merlinb View Post
You should email John Brokie (Tubecad) with these questions as they are specific to his PCBs.
I tried, but i had no answer...
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Old 28th August 2014, 02:25 PM   #10
Merlinb is offline Merlinb  United Kingdom
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Quote:
Originally Posted by Luca72c View Post
I tried, but i had no answer...
The PS-3 looks like it is suitable, if the heater regulator is an LT1084 or LT1085...

You could ask for a transformer heater winding of 10Vrms, 3A.

Last edited by Merlinb; 28th August 2014 at 02:33 PM.
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