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Old 5th February 2012, 08:45 AM   #1
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Join Date: Jul 2010
Default low voltage dc tube phase splitter/12AU7

I intend to run my pair of yahmaha B-5 amplifers 350w/4ohm per channel as monoblocks. should give 700W/Channel 8 ohm in two monoblocks.

It has no bridge function, so i intend to use phase splitters using tubes , my choice is 12AU7 running on 12v Dc battery to avoid humming and noise issues and donot need much gain as it would be used only for phase splitting.

Can anyone guide is it ok to do in the first place.If so where could i find a tested low voltage 12AU7 long tail time tested design. If driving the amp to full would be a problem may be i would use a dirct coupled MOSFET with constant current drain. Any help here ???
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Old 5th February 2012, 08:56 AM   #2
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P.S the amps are running mains crossed over at HP 80 Hz, so Bass roll off is not an issue here.
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Old 5th February 2012, 09:00 AM   #3
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If you check the Ua/Ia curves you will see that this is is a really lousy idea.
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Old 5th February 2012, 09:30 AM   #4
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you mean low operating voltage for the 12AU7 ???? ok what about +/- 24 V from SMPS
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Old 5th February 2012, 09:44 AM   #5
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PS. Would the bridged configuration with inputs out of phase and output across hot pins of both channels would be same as the marketed "fully-balanced" monoblock amplifier and would it offer any sonic advantage like high CMMR/noise reduction etc ?
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