Pavel Macura's MOSFET Power Follower - diyAudio
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Old 12th November 2004, 12:30 AM   #1
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Default Pavel Macura's MOSFET Power Follower

I've been looking into this circuit for a long time, and am finally going to build it.

I ordered some of the zeners today from www.centralsemi.com, noticing a little too late they were only 250mW models. Is this enough?

I don't have any IRF350 or TIP141. Instead, I have TIP121, which should work also, and Vishay SUP75N03-07. I am sure the TIP121s are fine, but it's the MOSFETs I am unsure on.

Here are the specs on it: 30V, N-Channel, 7 Mohm. The only part I am unsure on is the voltage handling only being 30V, when this circuit is designed for 40V. Would I just have to run it at a max of 30V?

Here is a link to the circuit: http://sound.westhost.com/project83.htm

Thanks!
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Old 12th November 2004, 05:18 PM   #2
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That's a pretty interesting design, I really like the simplicity. That, and the DoZ preamp can be made for nothing in an afternooon.'

Might have to give it a try. I need something like the DoZ anyway for Susan Parker's differential MOSFET zero feedback "gate follower" design from this long thread .

Click here to see the schematic: Click the image to open in full size.
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Old 12th November 2004, 07:28 PM   #3
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I don't see any advantage to using the darlington in there. I built a pair of power followers designed by Andrea Cuffoli a number of years back and he used two mosfets of the same type. They worked really well but there was still that annoying outut coupling cap in there to hold back any real detail in the sound... The followers I built gave almost exact same performance as yours.

Personally I just don't see any advantage to building power followers unless its for the learning experience. There are other simple amps out there that will give one a heck of a lot better results. In building a power follower you are for instasnce most of the way to building a Pass Aleph 3/30 design....... Building a power follower involves the same difficult and expensive sections of any class A amp.... the power supply, heat sinks, and chassis..... The rest is nickle and dime stuff... literally...... I would never waste time building power followers again.....

For whats its worth here is Andreas design which I believe you will find is alot better because of the virtual battery addition.... if you're going to bother building any....

Mark
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Old 12th November 2004, 09:00 PM   #4
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So, if I were to not use a preamp, and connect the output of a CD player directly to the input, the sound would be no louder than the input signal? What I have to do is use a preamp to take care of the gain?

And, I'm still wondering if I can use the mosfets and zeners i have...
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Old 12th November 2004, 10:36 PM   #5
eLarson is offline eLarson  United States
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If your room is small and your speakers fairly efficient AND if you don't like to listen terribly loudly... who knows. You may like it.

Then again, if your CD player doesn't have the current capability to drive the gates of the MOSFETs effectively... maybe you won't.

All in all, you should still be able to use the heatsinks and whatnot for a future project.
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Old 17th June 2009, 03:13 PM   #6
shaan is offline shaan  India
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Default mosfet alternative

hi, i've just finished making one of PMA's MPF with DoZ preamp as the voltage amp.
i had some spare irf540s and used one of them in the amp.
i haven't listened to any valve amp yet, however, there's no doubt MPF's output is better than any solid state amplifier i've ever seen and made and heard. its dynamic range is clearly way better than national's lm3886 amps i made some days ago. and EVERY element of any kind of music sound stunningly real! to be truthful i feel immobilized when it's on and making some sound! like found the holy grail of amps! thanks a lot to PMA for it.
now what i have been the problem is that i've searched for irfp240 and irfp350a but didnt find any here.
please tell me whether there are more alternatives.
thanks.
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Old 17th June 2009, 08:10 PM   #7
forr is offline forr  France
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Ciufolli's circuit has something fascinating and very unusual, it's a shunt amplifier, just like there are shunt regulators.
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Old 18th June 2009, 01:02 AM   #8
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forr,
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Ciufolli's circuit has something fascinating and very unusual, it's a shunt amplifier, just like there are shunt regulators.
It's a rather usual amplifier and everything is in the signal path (necessarily).
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Old 31st August 2009, 04:39 PM   #9
shaan is offline shaan  India
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Default I have a question-

Will the follower work if I replace the MOSFET with an IGBT?
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Old 31st August 2009, 05:32 PM   #10
PMA is offline PMA  Europe
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Quote:
Originally Posted by shaan View Post
Will the follower work if I replace the MOSFET with an IGBT?
Yes it would. You can try it, but I guess you will return to the MOSFET.
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