MOSFET power follower project

[Ilianh]

I'll be using a Pass Balanced Line Stage,

Thats one of the reasons I asked if anyone hard built/heard one of those amps, to know how they sound and to hear some opinions on the subject.

[Jay]

Hmmm... I think you will be dissapointed with the result

With my system, this is what I felt:

1. BOZ + Power Follower 99.
By bypassing the BOZ, I didn't need a volume control. I prefered to do this even I didn't get the sound details (you must know what I mean)

2. BDOZ + Power Follower (Pavel Macura).
I prefered this than the previous settings.

3. Aleph is better.

[Ilianh]

My other choice is actualy making a ZEN amp.

Wich can give around 10 watts, the problem is that the part of the speaker i'll be driving with that amp will have a mid thats 6 ohm, and a tweeter thats 8 ohm.

I'm not sure if 10 watts will be enough, and I read here
http://www.passdiy.com/pdf/zenamp.pdf
that the zen output power decreases when using speakers with impedances lower than 8 ohm..

Is it possible to play with the bias current to avoid that?

3. Aleph is better.

you are probably right, but an aleph would cost more too... I only need around maybe 15watts for this system.

[Jay]

If you think you need 15W, 10W won’t make any difference.

As long as you need only to hear your system from inside 4X4m room, even 4W can be enough, especially if you have efficient speaker. With more than 30W, the sweet spot for the bass might be outside of the room.

Sure you can increase the power (with bias current, rail voltage, Aleph “feedback”), with the price of power dissipated as heat.

With Aleph current source (Zen4 also use it), impedance is not an issue. And this current source will fulfill your power requirement.

I enjoyed my Zen more than Aleph. And it was not expensive. Be economical on the capacitance of the regulator.

[Ilianh]

I'll biamp this system, the bass is on another amp.. the mids/tweeter section will run on this zen or follower, theres nothing under 500 hz comming from it.

drivers aint that efficient.
not sure how much... but not in the 96db/w/m range for sure

I think I'll go with BOZ and a zen amp..

[PMA]

Hi Ilianh,
I am the author of the project, so let me tell something about replacement transistors. You can use IRFP350 (the same as IRF350, but in TO-247 case), or IRFP250.
I would not recommend IRF540 and similar transistors in TO-220 case. The reason is that TO-220 has approximately twice higher thermal resistance compared to TO-247 and you can easily get to the thermal troubles. Please visit my original page for newest info.
Compared to ZEN the Mosfet power follower sounds and measures better. It has lower distortion, higher damping factor and higher input impedance than ZEN. MPF is also able to drive difficult loudspeaker loads, the ZEN suffers from low damping factor.
Pavel

[peranders]

I'm really puzzled, what are the benefits of using this buffer instead of a ordinary amplifier?

[PMA]

peranders,
Nothing special. It is the same question as "what are the benefits of building ZEN instead of a ordinary amplifier?"
It is a simple project for the beginners in electronics and it has very reasonable parameters. That's why I have done it. And it gives better sonic and measured results than the ZEN amp, it was my answer to the ZEN.
Pavel

[JoeBob]

While I haven't built pavels follower I have built a MOSFET power follower amp (derivation of Andrea's). And I can say that it has a very "transparent sound", with a BJT preamp it sounds very different than with a tube stage in front, I very much enjoy mine.

[shaan]

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.