MOSFET Amplifier IRFP240/IRFP9240 - Page 56

harizhent · 10th May 2012, 06:22 PM

I have just assembled this amp and whant to double check if i understand right, how bias adjustment is done.
As i understad... i need to measure voltage acros of any 0.47R resistor and adjust pot till voltage reachess 30mV? That is it or im missing something?

apexaudio · 10th May 2012, 08:38 PM

Quote:

Originally Posted by harizhent

I have just assembled this amp and whant to double check if i understand right, how bias adjustment is done.
As i understad... i need to measure voltage acros of any 0.47R resistor and adjust pot till voltage reachess 30mV? That is it or im missing something?

Yes, but if you can't set 30mV replace 470R pot with 1k.

harizhent · 11th May 2012, 04:25 AM

Hmm voltage was riseing till reached ~35mV and started droping.. after it reached ~17mV...bam... fuse is gone and with that one pair also

Im sure i have missed something...

apexaudio · 11th May 2012, 08:54 AM

Quote:

Originally Posted by harizhent

Hmm voltage was riseing till reached ~35mV and started droping.. after it reached ~17mV...bam... fuse is gone and with that one pair also

Im sure i have missed something...

Can you post pictures?

harizhent · 11th May 2012, 09:57 AM

Ofcourse. Apex could you help me determine the problem?

shreya · 13th May 2012, 10:47 AM

How much RMS power i can get with +/-60Vdc at 8 & 4 ohms??

AndrewT · 13th May 2012, 11:02 AM

work it out !

donpetru · 13th May 2012, 11:08 AM

Quote:

Originally Posted by shreya

How much RMS power i can get with +/-60Vdc at 8 & 4 ohms??

Look at the next table in the article below (an article of two pages - see last table):
Surse de alimentare liniare pentru amplificatoare audio - calcul, teorie, concluzii - Surse de alimentare - Tehnium Azi - Articole (Articles) - Comunitatea Tehnium Azi

djk · 14th May 2012, 12:44 AM

It really depends on the regulation of the supply, how many VA the transformer is, the µF of the caps, and whether or not you use a high voltage tier for the front-end.

It could be as little as 100W/8Ω or as much as 200W/8Ω.

The Hafler DH200 was rated at 100W/8Ω and ran on ±63V, the XL280 (with another pair of outputs) ran on the same voltage but added a high-voltage tier for the front-end and clipped at 180W/8Ω.

harizhent · 14th May 2012, 06:37 PM

Apex as i promised i have uploaded photo of amp

Later im going to make more photos, but first i need to fix that ifps's blowing problem.
Power suply is being used from montarbo active monitor +/-75v 2.1A(per rail) +2x10.00o0uf.

14th May 2012, 12:44 AM	#559
djk diyAudio Member Join Date: Feb 2001 Location: USA	It really depends on the regulation of the supply, how many VA the transformer is, the µF of the caps, and whether or not you use a high voltage tier for the front-end. It could be as little as 100W/8Ω or as much as 200W/8Ω. The Hafler DH200 was rated at 100W/8Ω and ran on ±63V, the XL280 (with another pair of outputs) ran on the same voltage but added a high-voltage tier for the front-end and clipped at 180W/8Ω. __________________ Candidates for the Darwin Award should not read this author.

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10th May 2012, 06:22 PM	#551
harizhent diyAudio Member Join Date: Mar 2012	I have just assembled this amp and whant to double check if i understand right, how bias adjustment is done. As i understad... i need to measure voltage acros of any 0.47R resistor and adjust pot till voltage reachess 30mV? That is it or im missing something?

11th May 2012, 04:25 AM	#553
harizhent diyAudio Member Join Date: Mar 2012	Hmm voltage was riseing till reached ~35mV and started droping.. after it reached ~17mV...bam... fuse is gone and with that one pair also Im sure i have missed something...

11th May 2012, 09:57 AM	#555
harizhent diyAudio Member Join Date: Mar 2012	Ofcourse. Apex could you help me determine the problem?

13th May 2012, 10:47 AM	#556
shreya diyAudio Member Join Date: Aug 2010 Location: Andhra Pradesh	How much RMS power i can get with +/-60Vdc at 8 & 4 ohms??

13th May 2012, 11:02 AM	#557
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	work it out !

14th May 2012, 06:37 PM	#560
harizhent diyAudio Member Join Date: Mar 2012	Apex as i promised i have uploaded photo of amp Later im going to make more photos, but first i need to fix that ifps's blowing problem. Power suply is being used from montarbo active monitor +/-75v 2.1A(per rail) +2x10.00o0uf.