Build This MoFo!

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#81
prasi said:
hello nicoch58,
are you making a joke? it isnt even fit for a retard! I am sure ZM isnt one. So, next time before posting comments that dont add value and are nowhere near the spirit of the forum, stop to think for a moment🙂.

regards
Prasi
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Prasi, why don't you keep your opinions and advice to yourself next time??

It was just a little humor on his part and not to be taken literally.

Besides...who made you judge and site moderator as to who can post comments "that don't add value and are nowhere near the spirit of the forum"?

Perhaps this is why we all must "stop to think for a moment".:judge:
 
#82
Continuing, here is the revised layout that follows UMS guidelines (80 mm x 40mm mounting holes and Mosfet mounting at 15mm away from mounting hole.) Also included cap pitch options for C1.

regards
Prasi
 

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#84
JPS64 said:
if allowed, rotate 180° C1 and place IN connector on the bottom near +V.

My 2 cent.

JP
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Hi JP,
Could be explored, yes. However, I wanted to separate the signal from high current traces. From the pdf of Mr. Rothacher, I guessed that he wanted to keep them separate too.. BTW an amazing write-up, makes an interesting evening reading and re-reading.
regards
Prasi
 
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#87
Dear Michael
Many thanks for the MoFo article. I particularly appreciated the calculations (as with LuminAria)

Since heatsinks and chokes for class A power amps are the more expensive parts why not put several amps in one and make them switchable?

The picture below shows "3R one" (repair-reuse-recycle) that features a
choke loaded De-Lite De-Lux with IXTH6N50D2 and
a MoFo with IRLP3034
 

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#92
Maybe a strange question, but what "quality" can be expected from a design like this? 😕

I have a couple of nice big power transformers that should give me 22VDC and I want to buy 2 Hammond 159ZC chokes (60 mH @ 2A). This combined with a nice Mosfet (IRFP250 or even a small hockey puck) should give around 20 Watts and a -3dB power limit (so 10 Watts) around 24 Hz. Good enough. 😛

But coming back to the basic question: can such a simple design compete with an Aleph J or F6 for instance? I already have enough power transformers and heat sinks for these. So money wise there is not a big difference for me. I have build a couple of amps before, so the complexity is also no issue (not that any of these amps are complex). My preamp has an output impedance of around 1k, but it can deliver close to 100V RMS. Also up to the task.

Is it naive to think a MoFo can compete with an original Pass design or not?
 
#93
ZV7-T meets MoFo

Just a brainwave: would it be possible to build 2 MoFo's and use a (cheap) Common Mode Choke? Run it balanced. Kind of ZV7-T like? But as Follower 😕

I made a coupled inductor in Spice and at least here it works (opposite orientation). But I don't know if I understand these common mode chokes good enough.

I am certain I'm making a huge error in my thinking (of course you cannot use a common mode choke). Can someone explain why this doesn't work (or maybe it does....). 🙄
 
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#96
Ralph G said:
Maybe a strange question, but what "quality" can be expected from a design like this? 😕
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You'll have to build it to find out for yourself. 🙂

Hammond 159 zc just seems to be unpotted close equivalent of 193T. Probably good enough for this purpose. I saw that one myself too.

But coming back to the basic question: can such a simple design compete with an Aleph J or F6 for instance? I already have enough power transformers and heat sinks for these. So money wise there is not a big difference for me. I have build a couple of amps before, so the complexity is also no issue (not that any of these amps are complex). My preamp has an output impedance of around 1k, but it can deliver close to 100V RMS. Also up to the task.

Is it naive to think a MoFo can compete with an original Pass design or not?
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I don't that's the most apropos question, naïve or not. Almost not even fair. How's it different from Zen in volt mode? Build it and find out. Perhaps there would be more comfort if an expert can attest to input loads greater then 600ohm. Perhaps that would make people feel better.

But not really fair to compare with full Papa amp, often at least 2 stage. This Mike R. project is open-ended for whichever front end your heart desires. The possibilities aren't endless but open for more diy-ing mucking about, and that's most of the fun. Think about where Mike R. is.... Luminaria ---> Mofo. So.. more VFET fun? sure*. Shoot, I'm hoping to feed this with an OPT-less SET. (gasp)

*what to do with those SJ28s.. Luminaria diff pair for us +/- DAC people? Now that's wild. (and above my diy paygrade)
 
#98
Zen Mod said:
done zillion times

Iron Pumpkin is pretty much exactly that , two buffers driving autoformer ....... common mode choke , center tapped choke , call it however you want
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OK, well, crazy idea ahead that will demonstrate my ignorance no doubt :scratch:

What if I use a dual secondary (or primary i suppose) power torroid for the inductor. I wire the secondaries in parallel, except reversing the direction of the coil. Ie the magnetic flux from each secondary is cancelling the other. Thus we get a large value iron core inductor from a power torroid that doesn't saturate with a DC current running through it.

(says the guy with plenty of spare transformers, but no air gap inductors)
 
#99
Mike this is superb - well done! I know I shouldn't say this but maybe a few more sleepless nights for you would be good news for the rest of us 😀😀


Can i just check, for the measurements in the document, what were the source and load impedances please ? I read it twice but may have missed it in my excitement 🙂
 
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