MOSFET Amplifier IRFP240/IRFP9240

[still4given]

I connect ground like in schematic from post =1266 and I use MJE340 for VAS Outputs was 2sk1529/2sj200 and irfp249/9240 in several pcbs there is no any bias or osccilation instability.

Do you think it makes a difference if the input ground comes from the spot on the pcb vs the input jack? I can very easily change out the VAS for MJE340. I have many of them. Did you build one with BD139 in bias spreader? Maybe that is also an issue.

 

[apexaudio]

Do you think it makes a difference if the input ground comes from the spot on the pcb vs the input jack? I can very easily change out the VAS for MJE340. I have many of them. Did you build one with BD139 in bias spreader? Maybe that is also an issue.

Yes there is ground loop in your build... I use BC546 for bias.

 

[still4given]

Yes there is ground loop in your build... I use BC546 for bias.

So you only built one for sub in class B. What about crossover distortion? Will this be noticeable in full range use?

 

[still4given]

OK, I installed MJE340 in VAS. I hooked up the grounds per the schematic. Still the same issue. Alone they seem behaved but with both channels powered it goes very high bias.

 

[nigelwright7557]

OK, I installed MJE340 in VAS. I hooked up the grounds per the schematic. Still the same issue. Alone they seem behaved but with both channels powered it goes very high bias.

For complimentary outputs source resistors are usually added for stability.
I use 0r22 with my irfp240/9240 amps.

The VAS should have 100 to 220pf across BC.

The diode from top 240 gate to power rail is a bit odd.
I have seen reverse biased diodes act like capacitors and pass rail noise to gate of mosfet.

My last comment is regards Vbe multiplier. It is currently set to 7v6 which could be a little high.
I usually use a trimmer in my bias circuit and slowly turn up bias until cross over distortion goes.

A few things for you think about.....

 

[apexaudio]

OK, I installed MJE340 in VAS. I hooked up the grounds per the schematic. Still the same issue. Alone they seem behaved but with both channels powered it goes very high bias.

Only difference to my builds is input ground connect to CT of 10000uF elkos under the PSU100 pcb.

 

[still4given]

Only difference to my builds is input ground connect to CT of 10000uF elkos under the PSU100 pcb.

There has got to be more of a difference than that. I cannot believe that one inch of copper trace is the difference between oscillation and no oscillation. The only thing left to try is to replace the BD139 with BC546 and see if that works.

 

[thimios]

YouTube
Stereo mode.

 

[thimios]

Scope test.

 

[Gurpreet Turna]

20mA amplifiers work in caffe bars as PA.
I suggest you to made TP2 preamplifier.

Hello Mr. Mile, can u please update TP2 with TP3 (bass, mid and treble).
Regards
Gurpreet

 

[jongjava]

MOS200 make impressed, with the simplicity of circuit and number of components.
I m using +-56 volt for rails. With single subwoofer @8 ohm it hit hard.

Since I have a pair speaker. I wanna make it duo.
What range of V rails, that recomended to using it as 4 ohm?

 

[apexaudio]

MOS200 make impressed, with the simplicity of circuit and number of components.
I m using +-56 volt for rails. With single subwoofer @8 ohm it hit hard.

Since I have a pair speaker. I wanna make it duo.
What range of V rails, that recomended to using it as 4 ohm?

Use +/-45V with 4 ohm load.

 

[still4given]

Scope test.

Not the best looking results.

 

[jongjava]

Use +/-45V with 4 ohm load.

Thanks, Apex.
I am using the same layout, probably your 1st design, layout that bc546 detached from main heatsink.

I am quiet happy with this amp.
Since it only used for sub, and works as class B.
Makes this amp, death cold.
with only Heatsink salvaged from old AMD cpu heatsink

Powering dual legacy 12" speakers, it could break my living room's windows.
😁😁

 

[jongjava]

Another question, could I using IRFP540 &9540 ?
With 45+- rails and 4 ohm load?

 

[apexaudio]

Another question, could I using IRFP540 &9540 ?
With 45+- rails and 4 ohm load?

Yes, but I use +/-40V max

 

[desislavov]

Hello , Friends !

Anybody know where i can find APEX HV350 lay or lay6 file ?

Thanks in andvance !

 

[still4given]

I just wanted to report back on the MOS200. I found my problem. In the FX100 PSU that I had built I use the wrong relay. The one I used connected both outputs together rather than switching them separately. This caused a direct short from the output of one channel to the output of the other. I discovered this when I built the FX100 3P. Armed with this knowledge, I revisited the MOS200 and I am happy to report that it is working. It sounds fine but it doesn't measure all that good. The square waves have a spike at the leading edge similar to post #1289. MOSFET Amplifier IRFP240/IRFP9240

I just didn't want to scare off someone who wanted to try this one.

 

[thimios]

Not the best looking results.

It is the only amplifier that i placed in the bin.
I think that Mr. Mail must redesign it.

 

[still4given]

It is the only amplifier that i placed in the bin.
I think that Mr. Mail must redesign it.

Yes, I agree. I can see where it might work for sub woofer since it is quite powerful for its size but it doesnt clip pretty. I accidentally snorted the output and blew one channel yesterday. Blew up the outputs and burned some parts on my PSU100. Seems the PSU100 doesn't provide any short circuit protection. Needs fuses. Anyway I'm not going to repair the MOS200. I'll just wait for Mile's next creation.

Blessings, Terry