Yes, I was a little concerned about the heat sink for the Bigun.
First thought was to do some cutting on the Dissipante heat sink to make the
TO3 case fit but decided it would be a messy job that would not look great.
I ended up finding a Wakefield #403K TO3 style heat sink from Mouser that just barely fits
in a 400mm chassis next to the pcb.
It's 120mm by 76mm, has a double surface heat sink and has 2 long flanges that
I greased with heat sink compound and bolted down to the large heat sink.
Looks to be doing all right. Seems to transfer some heat to the large heat sink and
to the touch the small heat sink is not too hot.
Small heat sink measures 44C and the large one 36C.
I'm running 1.3A bias now. Zenmod's instructions say I could go to 1.5A so
will try that next.
Bruce
Attachments
do not
stay at 1A3 ....... or - even better - decrease that to 1A or so
to refresh memory (of all of us), snippet from post #1:
everything to save that old one happy and long time singing
do not worry - A Class envelope is insane without source/emiter resistors
these amps are making even lesser KlunK! than usual Papamps, except XA25
stay at 1A3 ....... or - even better - decrease that to 1A or so
to refresh memory (of all of us), snippet from post #1:
everything to save that old one happy and long time singing
do not worry - A Class envelope is insane without source/emiter resistors
these amps are making even lesser KlunK! than usual Papamps, except XA25
Nice looking Bigun Bracket there Twitchie! Very clean!
I'm biased now at 1A so as not to abuse the Ge Biguns from the
Mighty One's stash.
After some long and careful listening I'm blown away by the clarity of
the Old Soul. And the bass has an awesome punch to it.
It gives me that in-your-face sound where you can clearly hear every track
on the mix.
Bravo Oh Mighty One!
I'm biased now at 1A so as not to abuse the Ge Biguns from the
Mighty One's stash.
After some long and careful listening I'm blown away by the clarity of
the Old Soul. And the bass has an awesome punch to it.
It gives me that in-your-face sound where you can clearly hear every track
on the mix.
Bravo Oh Mighty One!
Even on Il Penitente, I can see M101 and M201 smiling at me mockingly ... 
Old fellows singing now. Can't type now, too busy enjoying ... will stay in the test mule airbnb until the boat from Italy arrives
Replaced mosfets for matched ones and channels are 0.16% and 0.15% THD now. H3 is -25dB down from H2. Can't wait to experience spooky
This is a very quiet amp as well. Ignore my noisy looking 60/120/180 spikes from test measurement. Can't hear anything with ear right next to 93dB sensitive Fostex test driver. At 1A bias, it's also barely warm as well.
Well done Maestro ZM! Will come back with listening impressions when I've had some time to get to know it better.
Old fellows singing now. Can't type now, too busy enjoying ... will stay in the test mule airbnb until the boat from Italy arrives
Replaced mosfets for matched ones and channels are 0.16% and 0.15% THD now. H3 is -25dB down from H2. Can't wait to experience spooky
This is a very quiet amp as well. Ignore my noisy looking 60/120/180 spikes from test measurement. Can't hear anything with ear right next to 93dB sensitive Fostex test driver. At 1A bias, it's also barely warm as well.
Well done Maestro ZM! Will come back with listening impressions when I've had some time to get to know it better.
Again, I fully embraced Papa's stance about amps - It's not mine to choose, mine is to make them ...... 
yup, dedicated thread will follow, these are just teasers ( because Bruce sorta forced me to put it on work bench, finally)
Plethora of Plethora following soon after Il Penitente (just for the record, from its name, you can judge how badly I'm influenced by Bubba Bob; Bad Cyclotron vibes emanating all the way from Ca to Serbia; so, it seems, even Cyclotron ways are leading to Rome )
bips are - in this case, first genuine ones I snatched from drawer - 2SA1491/2SC3855 ....... but pretty much any "for Audio amp" complementary pair should work well ........ 2SA1943/2SC5200 , TTA/TTC (newest Toshiba incarnation of 2SA/2SC)
yup, dedicated thread will follow, these are just teasers ( because Bruce sorta forced me to put it on work bench, finally)
Plethora of Plethora following soon after Il Penitente (just for the record, from its name, you can judge how badly I'm influenced by Bubba Bob; Bad Cyclotron vibes emanating all the way from Ca to Serbia; so, it seems, even Cyclotron ways are leading to Rome
)bips are - in this case, first genuine ones I snatched from drawer - 2SA1491/2SC3855 ....... but pretty much any "for Audio amp" complementary pair should work well ........ 2SA1943/2SC5200 , TTA/TTC (newest Toshiba incarnation of 2SA/2SC)
Not being sure what that cyclotron is, looked it up and got this:
https://slidetodoc.com/canadas-national-laboratory-for-particle-and-nuclear-physics-17/
Getting curious now …
Bubba Bob will tell more, if in moodNot being sure what that cyclotron is, looked it up and got this:
https://slidetodoc.com/canadas-national-laboratory-for-particle-and-nuclear-physics-17/
Getting curious now …