SissySIT

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T

Twst

Member
Joined 2017
Temporary cooking instead of my F6 :)
Should be making music soon!

Thanks Zen Mod!
Following your instructions from the build thread was a breeze. Only had trouble with a faulty 10k pot for the offset - had to go with a 5k and a somewhat larger R18. But it seems to be stable and all good!
My THF51s from watanabetomoaki wasn't really matched, but it will have to do for now ;)
 

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Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
looking good!

common mode chokes could be better , but not really sure for SissySIT , due to uneven loading of rails - Mosfet is always doing much harder work than SIT , so load on neg rail is greater than on pos

Ugs matching of THF is not critical , as long you're able to set Iq , who cares for Ugs difference
 
chede

chede

Member
Joined 2016
Paid Member
Twst, that amp looks great !
I like the three-dimensional Meccano-style construction that enables your "significant" power supply ...
It is a pity to hide the beautiful Toroidy transformers inside the amp ...


In my build, I'm happy with 4 pieces in my PSU of the little brother of the chokes you used - 156B (1.5 mH, 5 A, 70 mOhms).

SissySIT is absolutely deadly totally silent on my 100 dB/W widebanders. :p

I'm listening to it at the moment - it's the most transparent and informative and also explicit amp in my system so far, very nice tone, nice bite where necessary as well, not too aggressive. It's hard to do something else (like reading this forum) while listening, which in my book is a desirable quality :D

Thanks, Zen Mod, for this amp ! :)

Best regards,
Claas
 
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T

Twst

Member
Joined 2017
Zen Mod said:
looking good!
Click to expand...
Thanks! ;)
Zen Mod said:
common mode chokes could be better , but not really sure for SissySIT , due to uneven loading of rails - Mosfet is always doing much harder work than SIT , so load on neg rail is greater than on pos
Click to expand...
Chokes was just an experiemnt - I dont think they to much different than resistors - but they certainly add up weightwise giving the amp a good feel in my back when moving it..

Zen Mod said:
Ugs matching of THF is not critical , as long you're able to set Iq , who cares for Ugs difference
Click to expand...
Yuup, seems fine - SITs reads 2V6 and 3V5 @ 23v 2A and biases up fine. Had to mess a little with the offset adjustment of the highest one, but changing R18 did the trick

chede said:
Twst, that amp looks great !
Click to expand...
Thanks mate! ;)
chede said:
It is a pity to hide the beautiful Toroidy transformers inside the amp ...
Click to expand...
I know they are in there - makes me sleep so much better :rolleyes:
Zen Mod said:
though , I have few things to complain about Twst's work:
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Of course you do :D

Zen Mod said:
-base plate is wrong oriented , lip better to put up , so no waste of space under it - one can place all mains cables beneath
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Pfft, gives more air and room for screws to not scratch anything :p

Zen Mod said:
-signal cables are too thick
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Should 15cm cable make a difference, it the same cable all the way to my sources :rolleyes:

Zen Mod said:
-his work space is too tidy
:)
Click to expand...
You haven't seen my other tables where I actually do the work :D


And for sound - this thing is unique. Especially in the top end. It is really pulling out all the details and even the details in the details. It's not sounding anything like the M2 or the other firstwatt builds of mine, that's for sure.
Feeding it directly form my Katana gives a large soundstage in my horns on top of the cornscala bass cab.
There are no noise or hum coming from this amp, and that's cool. Had some mu-metal ready for the input autoformers - but it doesn't seem necessary at all.

As for the details, it kinda seems over the top with some recordings - making it somewhat bright/fatiguing. But not the regular sibiliant kinda bright. Might settle after a while - but overall I am impressed with the involving soundstage of this thing ;)

And oh, it runs a little hotter than I expected. Its like aleph hot!

Now, back to music :hphones:
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
@Twst - it'll settle ..... everything needs some burn in , caps in PSU , Iron , little Elna ....

our Italian friend found that he prefer higher voltage 1uF MKC as bypass for Elna Silmic (vs. these MKC I'm sending) , but I can't confirm - didn't tried and ....... I'm blessed with some time spent with Elephants , so my ears are much easier satisfied than ears of regular Greedy Boy

:clown:
 
Mazeppa

Mazeppa

Member
Joined 2009
I am in contact with pras re: THF-51S for SissySIT.

As an electrician whose primary amp building skill is knowing how to solder, I request confirmation from the group as to whether there are a pair of SIT's pictured here that will enable my Sissy to sing?
 

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R

Russellc

Member
Joined 2003
Paid Member
Zen Mod said:
I'm still confused how you got them differentiated as right and left ?
Click to expand...

You have to look at one of them in mirror, then it is clear.

I am paranoid about silly details as well! Must clear head of all doubt, if way mess up, I will find it even if requiring quantum physics.

Head must be cleared of all sillyness before solder is applied. I am master of anvil destruction with rubber hammer.

Russellc
 
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