These days I went ahead with the tuning of the amp. After a long battle I can say I got where I wanted with the enclosure I had at hand (there will be more with the future monoblocks) so I settled on 56Vdc for the ps and a bias of 2A.
I had some Lpads that made my life easier when doing the adjustments but even like this it took some time.
After I listened with the amp set in different ways I adjusted it till I got the best performance at 4r and then did same procedure for 8r. I had the pleasant surprise to see that same settings work great for both 4r and 8r.
Without a fft analyzer its a bit of a lottery getting to the best settings because probably you have different gain devices and it doesn`t help using same values for certain components, here you have to do your homework if you want the best implementation.
So here is how 27w/4r look
Then with the same settings here is how it looks at 20w/8r
Then I measured the mosfet modulation into 8r which was ~24%. When I seen that also the modulation is where it should I think you can imagine how happy I was that this time I nailed it 🙂)
Now probably you ask how it sounds.. what I can tell is that once adjusted properly it worth all the effort.
Edit: forgotten again but now was in time for an edit
Here is how h2 looks at 27w/4r
And here at 20w/8r
I had some Lpads that made my life easier when doing the adjustments but even like this it took some time.
After I listened with the amp set in different ways I adjusted it till I got the best performance at 4r and then did same procedure for 8r. I had the pleasant surprise to see that same settings work great for both 4r and 8r.
Without a fft analyzer its a bit of a lottery getting to the best settings because probably you have different gain devices and it doesn`t help using same values for certain components, here you have to do your homework if you want the best implementation.
So here is how 27w/4r look
Then with the same settings here is how it looks at 20w/8r
Then I measured the mosfet modulation into 8r which was ~24%. When I seen that also the modulation is where it should I think you can imagine how happy I was that this time I nailed it 🙂)
Now probably you ask how it sounds.. what I can tell is that once adjusted properly it worth all the effort.
Edit: forgotten again but now was in time for an edit
Here is how h2 looks at 27w/4r
And here at 20w/8r
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Didn't Nelson say something about a future amp named The Outer Limits ? Is there any more info about this ?
the SIT5 seems so good that we have totally forget the existence of the SIT4 😎
You do get a bit more output power and lesser thd so its double shiny 
don't get me wrong, I think it's awesome! I have parts too so when the smart people have it all figured out I'll jump in.
Srajan continued finally his SIT-5 review!
:--))
always a long waiting and still not finished.
https://6moons.com/audioreview_articles/firstwatt-sit5/4/
:--))
always a long waiting and still not finished.
https://6moons.com/audioreview_articles/firstwatt-sit5/4/
I used to enjoy reading 6 Moons, a lot,.. the pictures are nice, but honestly I can't stand the flowery descriptions.
So the SIT5 uses the MOSFET puck for voltage and the SIT for current... Is that it?
I've been thinking of using the Sissy for voltage gain into some 50w ( 2 8ohms in series so I can drive the output from either the 8 or 16 ohm load ) resistors on a large heatsink and taking that into an F4.... sort of the opposite. I think that ought to drive 35wpc. I did all the calculations last year. I got all the parts but I got no room to put it... I wonder, will that set up sound more like a SIT4 on steroids?
The XA252 SIT sounded fantastic... If I could have that sound again, I'd be likely set for a couple of years... I wonder how different the XA252 SIT and FW SIT5 sound.
So the SIT5 uses the MOSFET puck for voltage and the SIT for current... Is that it?
I've been thinking of using the Sissy for voltage gain into some 50w ( 2 8ohms in series so I can drive the output from either the 8 or 16 ohm load ) resistors on a large heatsink and taking that into an F4.... sort of the opposite. I think that ought to drive 35wpc. I did all the calculations last year. I got all the parts but I got no room to put it... I wonder, will that set up sound more like a SIT4 on steroids?
The XA252 SIT sounded fantastic... If I could have that sound again, I'd be likely set for a couple of years... I wonder how different the XA252 SIT and FW SIT5 sound.
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The SIT 5 is a common drain voltage follower without feedback. It has a voltage gain front end, and does its job with a P channel partner which is allowed a minor but variable contribution, adjusted to what I consider the sweet spot.
Apparently I have chosen the correct spot....
😉
Apparently I have chosen the correct spot....
😉
When I had German in grade 10, the teacher asked a boy to write out a sentence on the board, with 'sechs' in it. To all our hilarity he wrote sex. More than 600 moons have passed since then. 😉
I went there a few times so was familiar with how number six is spelled because of that I was laughing, though first time I heard it I didn’t knew to much german and to tell you more.. I heard it from a blonde german girl so imagine where my thinking suddenly went 🙂)
Back to Sit 5..
So what Pa wanted to tell us through the 6Monns review with this technical detail is that sit works more with low loads and mos works more with higher loads?
So guys with lower loads speakers will have more sit sound huh? Lucky them... just gave away my old Elac bookshelfs that dipped to 3.4r but no problem this time.. I can parallel some resistors to the Tannoys 🙂)