Magic - My first Lateral MOSFET Push-Pull amplifier

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Overkill

Since I have decided to put these two amps in my soon-to-be-born music system, I am feeling very excited. And although currently bias is limited to ~90mA per channel, I plan to run them at a bias of ~250mA, which the FETs are probably not ready for with the current pentium-iii heatsinks.

I have tested the p3 heatsinks with high bias. They get angry very quickly and demand airflow with 250mA of bias(it's the magic of summer). So I am making an upgrade... and also presenting the FETs a nice and beautiful gift.

P4 heatsinks.

Larger and cooler.

LOL I have bought 2 of them. Plan to recruit one for each FET. So gonna buy two more soon, may be tomorrow.


.....
 

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Bass testing the amplifier on my "Specially Made Metal Back" round-shaped subwoofer of 4ohm impedance. Signal is filtered with the ELF subwoofer processor from ESP, a hanging, naked and highly portable version of it. :D Shown in third attachment. The subwoofer was run with the high-ish 2.2ohm Zout of the amp.

The result is excellent. Tight and deeeeeep bass notes are produced very well, I expected the sub to act funny with the high Zout but it surprised me. Note that the sub has no damping installed inside. Still the sound was definitely better than P3A's output with low impedance. Probably because the rise of impedance of the voice coil at resonance causes the amp to deliver more power to it. It's just an illusion then...

Although I am going to use the amps for mid+high only, I am now convinced that it can take the place of my sub-amp too... maybe with a bit increased supply voltage.

I expected the zeners to produce artifacts into the 4ohm load in medium volume because of the higher current need at lower load, but clipping occured at much higher volume than I expected. Either the zeners are dead or my sub is very efficient! :D :cool:
 

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Some Basic Measurements.

The distortion spectra is of 1kHz sine-wave at 20V P-P output on 5ohm resistive load. If I am not wrong then THD seems to be around 0.001%. Negligible amount of even harmonics and a tiny bit of odds. As with all PP amps, odds are dominant.

There is also a sweep test. Looking at the graph I can say that this amp has a large power bandwidth. Although the graph starts falling after 16kHz or so, I think the limited response of the awful onboard soundcard is responsible for this. Because the crystal-clear highs that the amp produces through the speaker gives hint to a totally different dimension which can NEVER be limited to 16kHz, as my ear and listening experience suggests.

However, the basic tests were a success and I had a lot of fun.
 

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Dear Shaan,

Last year I read with great interest your post about Pavel Macura's MOSFET Power Follower without darlington and after a lot of reading about amplifiers, I decided to built it. I have not done it yet, I am very very slow in making decisions. But now, I see that you propose this Lateral MOSFET Push-Pull amplifier. So I would like to know your thinking about the two types of amplifiers, is this new one really better ? The difference is significantly higher so I shouldn't bother build the Power Follower, or the PF still woth making it.
Thanks for your advice.
 
Dear Shaan,

Last year I read with great interest your post about Pavel Macura's MOSFET Power Follower without darlington and after a lot of reading about amplifiers, I decided to built it. I have not done it yet, I am very very slow in making decisions. But now, I see that you propose this Lateral MOSFET Push-Pull amplifier. So I would like to know your thinking about the two types of amplifiers, is this new one really better ? The difference is significantly higher so I shouldn't bother build the Power Follower, or the PF still woth making it.
Thanks for your advice.

If you have read about/listened to either of the JLH, the Zen, the Death of Zen, the Hot Follower 99, Le Monstre etc. amps already AND liked their sound but want even lower output impedance with pure SE Class-A and no intended CCS current modulation then you should not drop PMA's MOSET follower. It is THE simplest of all, having the same sonic signature. Remember I am saying this because you have decided on follower project. If you can still change your decision then do a rock-paper-scissor on the above amps.

Regarding the LATERAL FET amp, it is a totally different amp with higher power and lower distortion than any of the above mentioned SE amp(of course). It doesn't sound "dry" or "harsh" or "boring" or "lifeless" to me. Has all the good habits of a well designed class-AB amplifier. You may be happy to make one(or two) and listen, but that doesn't mean it renders MPF worthless. "Better" or not? That's totally subjective criteria and the opinion is top secret.

Sad news, you have to listen to both in order to know which suits your ears best. Each has it's own place and own audience, you choose your team.

I love them both and have them both, plus have JLH, ZEN, DOZ too. I love them too, coz they all produce good music.
 
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