SissySIT R.3

[nautibuoy]

I'll still check it when I get both channels operational. I was thinking a piece of grounded copper clad PCB material might be a good idea but it looks as though it'll be unnecessary.

 

[Zen Mod]

copper , mile thick, to prevent magnetics

 

[nautibuoy]

Hi again Mighty ZM.

I tried finding the info but no joy - what input level does SissySIT require to deliver its 18W output (into 8R load)?

IN due course I wouldn't mind giving it a run with my 15ohm Lowther horns - any observations on that possibility?

 

[Zen Mod]

18W@8R voltage divided with gain of 4V/V

(18W *8)
square root of that, you get Vrms - 12Vrms

multiply with 2, you get Vpeak - 24Vpeak

multiply with 1.41, you get Vpp - 33.94Vpp

so, output of 12Vrms, demands 3Vrms in

 

[Zen Mod]

even Andy and Pepennino already know that calculus

 

[nautibuoy]

even Andy and Pepennino already know that calculus

Yea, it's easy when you know the voltage gain...

 

[Zen Mod]

it is evident from schematic ...... and info about xformers used

 

[nautibuoy]

it is evident from schematic ...... and info about xformers used

Not if you're stupid!

 

[Zen Mod]

ZM's life is great:

 

[nautibuoy]

In the UK the saying is 'as happy as a pig in ****'...

 

[randytsuch]

Quick question. How do I calculate power dissipation in the parts that need heatsinking? The 9140 and the SIT?

So far, I was just using IV to do a rough calculation, but would like to figure out for each part now.
I don't expect a problem with the lowish bias I'm going to use.

Randy

 

[Zen Mod]

IV, nothing else

lsp out being in exact middle between rails, so 0V, means each part in OS seeing exactly rail voltage, while same current flowing through them

dynamically, other story (as shown long ago) , but we can ignore that, when dealing with heat

 

[randytsuch]

With my 04/400 chassis, I think the heatsinks are 0.38 c/w each, with 2 per side.

If my calcs are right, I get 13 deg C rise. On a warm summer night at 27C, a 40C temp is pretty reasonable.

 

[Zen Mod]

04/400, good for 80W of heat per side, all year long
though, I;m using Babysitter in summer, OCD for cringing caps

 

[ggetzoff]

they are certainly more clever than Moi

choose 600:600

https://edcorusa.com/collections/ma...-matching-transformers?variant=41109443346619

Choky,
No one is smarter than you (except maybe Papa) and you never, ever make mistakes!😉

 

[ggetzoff]

FYI, if you call soon, you should be able to cinemags soon. They have scheduled a run of them in a few weeks.

I ordered the Edcors. I’ve got other projects to do until they get here in May! But thanks!

 

[Zen Mod]

Choky,
No one is smarter than you (except maybe Papa) and you never, ever make mistakes!😉

you know , I really thought long and hard about that

no wonder that Papa is smarter than even Mighty Moi - I did taught him everything I know, then he did some tricks of his own!!

fact that he's slightly older than Mighty Moi, so he was making speakers and amps on day when I was born, is irrelevant - those talented guys are good even at precognition routines !

go figure ......

 

[ggetzoff]

davidjt,

Welcome to the club. I think your in a good shape with the SITs you have. The SissySIT is a great amp. I love mine and the next in the cue for me will be the Singing Bush. I would have already pulled the trigger but a pair of SS magically came into my possession thanks the codyt and NP.

Just remember you can’t have to many amps.

Did you build the Singing Bush?

 

[nautibuoy]

Another very happy greedy boy!

I have set up the second channel of my SissySIT, which went swimmingly, and have been listening to music in stereo through some proper speakers, albeit a pair of old Mission floorstanders and via dubious temporary hookup wire/connections. I'm using my Noir headphone amp as a preamp as the source is currently just my smartphone (playing FLAC media files) - the 6dB gain of the Noir is just right. I can already hear how good this amplifier is!

The only minor issue is a tiny bit of transformer buzz that I'll need to check out, though it is inaudible unless you're within a metre of the amp.

All I need to do to finish the project is to fabricate front and rear panels and hook-up the socketry.

Thank you Mighty ZM.

 

[davidjt]

I wish my metalworking skills were up to that standard! A superb build. (Is there a 'Fugly: Level2'? Superfugly?)

But if mine sounds as good as the DIY VFET/2 I'll be well satisfied.