F5 bias

AudioSan · 20th March 2012, 12:17 AM

hello

i have 2pc 225VA transformers in my F5. and a bias of about 1.72A(cviller's dual output's) and the transformer(only one ch yet) is nice and cool. about 32C.
anyone have an idè of how much i can crank the bias with those transformers? heatsinks is also nice and cool. maybe 37-38C ambient is about 22-23C.
rigth now bias is 1.72A. DC ofsett -0.4mV- +0.4mV

Zen Mod · 20th March 2012, 12:24 AM

up to 50W per mosfet

AudioSan · 20th March 2012, 12:30 AM

50W pr mosfet on a 225VA?
thats 200W. i don't want to boil the transformers

Bksabath · 20th March 2012, 12:35 AM

225 VA is not much to go on as it is the voltagge time current
so what voltagge is it?

If it is split secondary at 18 and 18 V 225 divided by 36 = 6.25 A total
Or you can take max 3.125 A out of each secondary

Papa reccomend a 3 to 1 margin so in respect to that you are already taking out enough.

rest is again realy meaningless as what size heath sink?
and ofset again got nought to do with it as it all down on how carefull you are when tweaking the pots.

If you go Papa class you need bigher trafoss

Bksabath · 20th March 2012, 12:37 AM

Still mighty Zen is right
50 W on each mosfet is max that is the given trought
Boiled trafoss irellevant we have them for breakfast

Zen Mod · 20th March 2012, 12:52 AM

I meant you wrote one 225 Watt-er per channel

so - if using original F5 schm , where you have 2 mosfets per channel , that means you're still in ballpark - 100W power consumption per 225W iron

AudioSan · 20th March 2012, 01:00 AM

225VA pr ch. 4 mosfets pr ch

AudioSan · 20th March 2012, 01:36 AM

yes it is 2x18V transformer. so +/-22-23V no itd 1.72A bias. and the transformeris at about 32-34C witch is about 80W i think it will have no broblem with at least 120W.
BTW. it sounds fantastic. i just love it. but it's too cool

AudioSan · 20th March 2012, 01:39 AM

here it is

AudioSan · 20th March 2012, 01:45 AM

the whole thing

20th March 2012, 12:17 AM	#1
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	F5 bias hello i have 2pc 225VA transformers in my F5. and a bias of about 1.72A(cviller's dual output's) and the transformer(only one ch yet) is nice and cool. about 32C. anyone have an idè of how much i can crank the bias with those transformers? heatsinks is also nice and cool. maybe 37-38C ambient is about 22-23C. rigth now bias is 1.72A. DC ofsett -0.4mV- +0.4mV __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers

20th March 2012, 12:24 AM	#2
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	up to 50W per mosfet __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

20th March 2012, 12:30 AM	#3
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	50W pr mosfet on a 225VA? thats 200W. i don't want to boil the transformers __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers

20th March 2012, 12:52 AM	#6
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	I meant you wrote one 225 Watt-er per channel so - if using original F5 schm , where you have 2 mosfets per channel , that means you're still in ballpark - 100W power consumption per 225W iron __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

20th March 2012, 01:00 AM	#7
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	225VA pr ch. 4 mosfets pr ch __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers


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20th March 2012, 12:35 AM	#4
Bksabath diyAudio Member Join Date: Dec 2007	225 VA is not much to go on as it is the voltagge time current so what voltagge is it? If it is split secondary at 18 and 18 V 225 divided by 36 = 6.25 A total Or you can take max 3.125 A out of each secondary Papa reccomend a 3 to 1 margin so in respect to that you are already taking out enough. rest is again realy meaningless as what size heath sink? and ofset again got nought to do with it as it all down on how carefull you are when tweaking the pots. If you go Papa class you need bigher trafoss

20th March 2012, 12:37 AM	#5
Bksabath diyAudio Member Join Date: Dec 2007	Still mighty Zen is right 50 W on each mosfet is max that is the given trought Boiled trafoss irellevant we have them for breakfast

20th March 2012, 01:36 AM	#8
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	yes it is 2x18V transformer. so +/-22-23V no itd 1.72A bias. and the transformeris at about 32-34C witch is about 80W i think it will have no broblem with at least 120W. BTW. it sounds fantastic. i just love it. but it's too cool __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers

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