simple question about PS for DX Blame MKII

ByronInLawrence · 8th July 2011, 04:10 AM

Greetings,

I'm considering building the DX Blame MKII supercharged or MKIII supercharged. I already have a pair of 300VA torroids with 40V, 3.7 Amp dual secondaries which I'd like to use up. They are not center tapped. The recommended rail voltage for the Blame MKII supercharged is +/- 56V, which is perfect for my 40V secondaries. However, I also saw that the power supply which Carlos recommends for the Blame series, requires a center-tapped transformer and 2 diodes for rectification. I'm making the assumption that 56 volts is 56 volts, and that I can use whatever supply I want, provided it supplies the correct voltage, and has enough current (300VA/channel should be plenty). But you know what they say about assumptions! I'd just like some confirmation that I'm right before I commit to the DX Blame MKII / MKIII and purchase a different PS board.

Thanks in advance!
-Byron

Tekko · 8th July 2011, 07:50 AM

Put one bridge rectifier on each transformer and wire + on one to - of the other and bingo, centertap.

300VA is a bit low but 50-75 watts per channel should be plenty anyways.

ByronInLawrence · 8th July 2011, 10:41 PM

Hi Tekko,

Thanks for the reply, but I think what you are talking about is different from a power supply using a center-taped transformer. This Wikipedia entry: Center tap - Wikipedia, the free encyclopedia shows the kind of power supply designed by Carlos for the blame series which can be seen here: http://www.nabucoeletronica.com.br/d...-schematic.pdf.
I can not convert a non-center tapped transformer to a center tapped one post-rectification.

Tekko · 9th July 2011, 10:00 AM

I have done this with two separate transformers and it works just fine.

Put the two transformers in series and you get a centertap, or do the same thing after rectification and you get a centertap.

Its essentially the same thing as when a transformer has two separate secondaries, you use two FW bridges.

AndrewT · 9th July 2011, 10:27 AM

A dual secondary transformer can be wired with the two secondaries in series. This is equivalent to a centre tapped transformer.

I use a 230:40Vac transformer and when powering two channels each biased to 210mA, I have +-58.5Vdc when mains is at it's usual 244Vac.

ByronInLawrence · 9th July 2011, 09:05 PM

OH! Now I get it!

Thanks guys.

8th July 2011, 04:10 AM	#1
ByronInLawrence diyAudio Member Join Date: Nov 2010 Location: Lawrence, a nice little college town in Kansas	simple question about PS for DX Blame MKII Greetings, I'm considering building the DX Blame MKII supercharged or MKIII supercharged. I already have a pair of 300VA torroids with 40V, 3.7 Amp dual secondaries which I'd like to use up. They are not center tapped. The recommended rail voltage for the Blame MKII supercharged is +/- 56V, which is perfect for my 40V secondaries. However, I also saw that the power supply which Carlos recommends for the Blame series, requires a center-tapped transformer and 2 diodes for rectification. I'm making the assumption that 56 volts is 56 volts, and that I can use whatever supply I want, provided it supplies the correct voltage, and has enough current (300VA/channel should be plenty). But you know what they say about assumptions! I'd just like some confirmation that I'm right before I commit to the DX Blame MKII / MKIII and purchase a different PS board. Thanks in advance! -Byron

8th July 2011, 07:50 AM	#2
Tekko diyAudio Member Join Date: Jan 2005	Put one bridge rectifier on each transformer and wire + on one to - of the other and bingo, centertap. 300VA is a bit low but 50-75 watts per channel should be plenty anyways. __________________ The point of life is to build atleast one audio amplifier before you die.

9th July 2011, 10:00 AM	#4
Tekko diyAudio Member Join Date: Jan 2005	I have done this with two separate transformers and it works just fine. Put the two transformers in series and you get a centertap, or do the same thing after rectification and you get a centertap. Its essentially the same thing as when a transformer has two separate secondaries, you use two FW bridges. __________________ The point of life is to build atleast one audio amplifier before you die.

9th July 2011, 10:27 AM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	A dual secondary transformer can be wired with the two secondaries in series. This is equivalent to a centre tapped transformer. I use a 230:40Vac transformer and when powering two channels each biased to 210mA, I have +-58.5Vdc when mains is at it's usual 244Vac. __________________ regards Andrew T.

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8th July 2011, 10:41 PM	#3
ByronInLawrence diyAudio Member Join Date: Nov 2010 Location: Lawrence, a nice little college town in Kansas	Hi Tekko, Thanks for the reply, but I think what you are talking about is different from a power supply using a center-taped transformer. This Wikipedia entry: Center tap - Wikipedia, the free encyclopedia shows the kind of power supply designed by Carlos for the blame series which can be seen here: http://www.nabucoeletronica.com.br/d...-schematic.pdf. I can not convert a non-center tapped transformer to a center tapped one post-rectification.

9th July 2011, 09:05 PM	#6
ByronInLawrence diyAudio Member Join Date: Nov 2010 Location: Lawrence, a nice little college town in Kansas	OH! Now I get it! Thanks guys.

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