What's wrong with the kiss, boy?

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Zen Mod

Zen Mod

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Joined 2003
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What's wrong with the kiss,boy ? ........ or - How I gained a gain ,little before Lee De Forest and little after Papa

lookie : Iron Pre | Zen Mod Blog

I already posted that link in few places here , but as it seems ,few Greedy Boyz are greedy for more info

cheap and clean way of having 6db (or little more ,with different gain device)

it's already everything written in that blog post , but to recapitulate :
-pot , then buffer of your choice , then 600:600 xformer connected as autoformer , voila! -there is 6db gain

if approach was good eons ago , when microfarrads and active gain devices were much more expensive than chunk of copper and iron,if approach is good for numerous mic input stages , if approach is good for F6 and especially M2 (buffer-autoformer-buffer) , it must be god for line stage too.

and yes , with 1+1 autoformer , Rout is four times Rout of buffer itself

xformers : Edcor have few , Jensen , Sowter, Lundahl etc.............

-do not expect that more expensive ones are necessary better sounding,
-do not expect maximum verity from buffer if you not use decent (shunt , my poison) reg.
-you can go wild and make your own autoformer , equipped with 24 taps , so skip pot on input and use autoformer at output, as volume attenuator and gain device ,as one device
-or you can make it this way - buffer -commercial AVC (200$ Slagle?)-output autoformer
-or you can go wild and connect commercial AVC to appropriate tap , as output autoformer and have 6db gain ...... that would be buffer -commercial AVC connected on proper tap

now I'm working on balanced Iron Pre ..... will post that soon too

edit on 11.10.2020. : last files for SE and Bal iteration are in posts #1149 and #1150
 
Last edited:
W

woody

Member
Joined 2002
Here is a cute idea to get 6db of gain from a buffer. Wonder if it would work with a B1 with a split supply ?
 

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Zen Mod

Zen Mod

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Joined 2003
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B1,yes, but which iteration ?

in case of JFet buffer made of same sex JFets , that means double Rout comparing to complementary JFet buffer ....... and Rout is veeery important when feeding xformer with lowish inductance
I would double JFets to decrease Rout
in fact - I would put both JFets in parallel , and put bjt CCS down , no output foolproof resistor
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
tnx boyz ...... as I said , I'm in age when I certainly forgot more than I know now .... :clown:

regarding buffer type - I'm working on Diamond buffer , which is going to have similar THD spectra as complementary JFet one , and even better when loaded hard
of course that most important advantage is 100% lesser number of preciousssssss JFets in it :rofl:

I couldn't stop turning my head in circles for day or so , trying to figure how's that I can't manage less than 25R on output , whatever I do ...... how's that possible that Diamond buffer is same as JFet buffer in that department , when I know that I both simed and measured bjt as superior to JFet , regarding Rout
and then , I realized that I'm constantly probing values for Rout calc on autoformer output ( not on buffer output) ..... while I was doing exactly opposite when calculating the same for JFet iteration :clown:
so - not bad , 25/4 R on buffer itself
we'll see soon , I'm getting pcbs in few days , will test them as Iron :Pumpkin:
 
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