Using Power MOSfets Instead Of L Mosfet

[sekhar]

I am new in this this field of audio amps . I have been consulting High Power Audio Amplifier Manual By G Randy Slone .
I want to make a 500W subwoofer amplifier but due unavailability of L Mosfet I am nt able to procced can any body tell how to use Power Mosfet(IRFP240/IRFP9140) instead of 2SK1058/2Sj162.

 

[lineup]

IRF mosfet are HEXFET
they are very different than 2SK1058/2SJ152 = lateral mos
So, strongly not recommended to use them to replace.
In fact, you would have to change the original amplifier so much
that it would be a different amplifier.

Much Better to try to find some nice MOSFET amp
that is built to use IRFP240/IRFP9240
For example Nelson Pass has designed a couple of such amplifier projects.

Regards

 

[Spirtos]

There are great differences between vertical (IRFP) and lateral type of mosfets (2SK/J). Allthough both can be used in power amps better dont use vertical insted of lateral type in specific designs, specially R. Slone's designs need a lot of modifications to suit vertical type mosfets and after all it will not be the same amp. As Lineup said better find a design which uses vartical mosfet. Try some search and Im sure you ll find a lot. Nelson Pass' designs are a good start.

Regards

 

[sekhar]

thanks a lot, but can u direct me towards any specific design. I am thinking about making "Citation 12" from the Nelson pass Labs or the IGBT amp from elector. Plz tell which is worth trying cause i have tried a lot of circuits from the net but many have failed ...... instead of the fact that i design my own pcbs.

And one more thing....... Plz tell if any heip needed on Pcbs ...... just upload the circuit I will try to send u the pcb

 

[nigelwright7557]

I would go with a modern IRFP design.
IRFP240 and IRFP9240 are cheap and plentiful.

I use them on my own designs and they perform very well.

 

[AndrewT]

Have a look at the various Quasi designs.

 

[nigelwright7557]

Have a look at the various Quasi designs.

RS Components do IRFP250 at £1-49.
Cheap as chips !
www.rswww.com

 

[sekhar]

Thanks for the advise "nigelwright" . Can u Send me Some of your design I am nt able to find good quasi complementary design.

regards

 

[nigelwright7557]

Thanks for the advise "nigelwright" . Can u Send me Some of your design I am nt able to find good quasi complementary design.

regards

I dont have a quasi design mine are all complementary using IRFP250 and IRFP9240.

There are loads of designs on here if you do a search for quasi.

 

[sekhar]

thanks "nigelwright" u can send ur complementary designs as well. I wanted to make quasi complementary amps because i didnt get L mosfets in India .
Neways currently I am making the following 125W design. If u can have a look at circuit plz it would be very helpful

regards

 

[nigelwright7557]

thanks "nigelwright" u can send ur complementary designs as well. I wanted to make quasi complementary amps because i didnt get L mosfets in India .
Neways currently I am making the following 125W design. If u can have a look at circuit plz it would be very helpful

regards

It looks good to me.
A pretty standard quasi circuit.

 

[sekhar]

can any body help me with the vbias setting for given schematic . The rated vbias for the given amp with four IRFP260 is 63mA at +-50V but if I increase the voltage to +-80V & increase the number of IRFP260 to 8 . then wat will be the new vbias. & wat other modification will be required !!!!!!!

regards
Ardhendu Sekhar Das

 

[AndrewT]

the bias stays the same at 63mA per device.
The dissipation goes up approximately three times so you will need approximately three times the size of heatsink.

BTW,
63mA of bias is low for a FET output amplifier.

Q1, how long till meltdown?

 

[The golden mean]

Hi Sekhar,
here´s a list of some provider´s of MosFet kit´s or modules.
Lede Audio is selling some of Randy Slone´s designs in kit form.
I have been in contact with both Anthony Holton of Ausseiamplifiers and the owner of Lede Audio, David and they seem to be responding properly.

However I can´t endorse any amp of theirs out of personal experience, but there is some information on this site (diyaudio) if you search, problem use to be the huge suggestions you get and many of them are not appropriate.

Regards

Håkan

http://www.ledeaudio.com/audio_kits.html

http://ampslab.com/index.html

http://www.aussieamplifiers.com/

 

[sekhar]

thanks andrewT, IS it ok for given amp to driven to +- 80V & there wont be any changes for circuit except the components that is BD139 will be replaced by some other high voltage & current counter part.....

& which transistor have u stated as Q1 ????????????Can u pass over some amplifier circuits that can generate 500W Rms in a 4E load using hexfets............

Regards
Sekhar

 

[AndrewT]

IS it ok for given amp to driven to +- 80V & there wont be any changes for circuit except the components that is BD139 will be replaced by some other high voltage & current counter part.....

& which transistor have u stated as Q1 ????????????Can u pass over some amplifier circuits that can generate 500W Rms in a 4E load using hexfets............

If you do not know how to select suitable components for the 500W duty you are planning, then this is the wrong amplifier for you to build with your current lack of knowledge.
Build a little, cheap 50W into 8ohm discrete using the 3stage Lin topology and experiment from there.

 

[sekhar]

can any body provide me with a high power audio amp circuit using quasi complementary design.........

 

[AndrewT]

Quasi.
He has about 4models/projects on this Forum.

 

[djk]

http://www.passdiy.com/pdf/citation.pdf