SemiSouth Donuts

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#41
buzzforb said:
R085 or R065 are most likely candidates. I found out from Mike that R065 is indeed enhancement mode, but with lower Vt than R100 of about .4V.

Question. How do you go about choosing transformer for this amp. I think you suggested 500VA and 110 secondaries. You know me, I dont know squat about chokes and this is first choke loaded amp.

Project down the road, as I am imbedded in another at the moment🙂, but i would like to order toroid now as part of GB.
Click to expand...

I just put an order to www.toroidy.pl for two 300 VA 2*18 V / 2*9V secondarys, nominal current equally distributed between 18 and 9 V secondarys. I also ordered two Mega Donut 3 kVA with only two windings, wound as parallell primarys for the choooooky.

Thanks MZM, Ill contemplate the schematics. Buzz, can you direct me to the suitable 3 legged critter? I'm more then dumb in that area.

Staffan
 
#44
Nobody seemed to appreciate this one in the f6 thread. Could have hoisted them right onto the back of the truck.

http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-405.html#post3431644

Stajo,
Semisouth fan has some SS SiC Jfets for sale, but the Cree can be had for less money and I have bought some to see how they perform. It might be good to try IRF before dropping the coin. If you promise not to toast them😀, Ill send you some R085 I have that are well matched. I willnot get to this for months, more tha likely. After my F5T GB gets shipped out, its Altec time for me.

I have been looking into LR RIAA's, but cant find any info on them other than folks trying to sell the chokes.
 
#45
ook them , choke sellers !

:rofl:

whenever you write , please specify about what you're writing - SJEP or SJDP .......

(don't hold your breath regarding Cree ; they can be best thing after bread , but most probably not ; though , worth playing )

playing with IRFP prior to tossing real McCay in is ........ cunning :clown:
 
#48
R085 are depletion mode, but as ZM said, shouldnnt matter too much, as CCS is in tail. IRF is good start, as it will give you baseline. Ill shoot the others in the mail whwn i get a second. r085, should trounce it, when all is said and done. i am building it largely to try choke load and learn about servos.
 
#52
it is there ( at least I see some file ) but what's still puzzle for me - why we need it ?

in fact - you need it ..... and Buzz maybe , too ...... but I don't need it

moi usually type values from schematic either ditto in online ordering thingie , or in wordpad file then from it to online ordering thingie
 
#57
nope ;

think strictly DC ; imagine choke as two plain resistors

what offset you can have , when one side is 4A , other is 0A ( even if that is least possible scenario) , while Rdc of choke is , say , 0R5

what's most important is , simply , overall Iq , ahem , steadiness
 
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#58
Zen Mod said:
it is there ( at least I see some file ) but what's still puzzle for me - why we need it ?

in fact - you need it ..... and Buzz maybe , too ...... but I don't need it
Click to expand...

Hehe, no but it can come handy for someone who wants to try it. I putted it there to comment on cause the comp numbers was a bit blurry in the first pic-post. Thanks for the pdf, much better.

When I posted a cut/paste from excel it looked handsome before I posted, but after it went on a straight line so I had to use my dual screens to even delete the message😀

Phew, did the beer bell just rang?
 
#59
It was. Can some(mighty)one interprete what we are seeing on those sim-curves. Is that your fallos on 1kHz.

In fact I had the idea for the 34th time to occur you on the spice sims but I brougt a work laptop w/o local admin rights on my easter holliday
 
#60
falos basic signal at 1K

the 2k 3k 4k 5k 6k 7k 8k etc

less you see them , the better , except basic one

but , what you see , must go down nicely and monotonic

here's the same (sim FFT) , but with minus input Dodo , upped plus input , working as unbal to bal converter

rising second harmonic , logically , comparing to full bal arrangement
 

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