B1 Buffer Preamp

[fgroen]

I suppose that you're running that trafo-based B1 on a symmetrical power supply. Otherwise, there will be quite some bias current running through the primary winding.

 

[codyt]

Its cap-coupled at input and output, so before it goes to the 600:15K's. Is that what you mean?

 

[Zen Mod]

well, single rail or dual, care is already taken that there is no DC on output

only - in case of single rail B1, I would put at least 1000uF (bypassed with your fave poison) as coupling cap between JFet sources and autoformer

 

[codyt]

Good idea

 

[Zen Mod]

as all mine are

 

[thirdicomplex]

Mine is the single rail. I hadn't even given any thought to the DC. Thank you fgroen for pointing that out and ZM for the solution!

 

[codyt]

as all mine are

Swapped to a bigger output cap – def made improvement to low-end

 

[Zen Mod]

I didn't gave any solution - all is already solved



shorting foolproof resistor and increasing value of output cap, that's trivial to deduce

 

[Zen Mod]

Swapped to a bigger output cap – def made improvement to low-end

how big?

no porn, no glory

bloody greenhorns .........

 

[codyt]

Nah, this guy is more an experiment than a porn star, but here you go. 1000uf bypassed with 1uf of polyprop on bottom

 

[Zen Mod]

and just imagine Level of Enormity which can be achieved only using proper shunt regs



Papa spoiled ya all, irreversible and enormously

next toys we are doomed to build are going to be full with BC109 and 2N3055

 

[codyt]

I'm using a salas shunt for this little guy. That said, Iron Pre easily beats this little setup.

 

[fgroen]

Its cap-coupled at input and output, so before it goes to the 600:15K's. Is that what you mean?

That's what I mean.

Still like my DC coupled B1 very much.

 

[Alexium]

Does the B1 *really* need two 15 000 uF caps? Seems a bit extreme for a low-current circuit.

 

[codyt]

You can use less. I remember using 4000uf x2 without audible differences. I guess it depends on the quality of your DC input too.

 

[A Jedi]

I looked at the schematics of both the B1 and B1 Korg but I'm not educated enough to understand the similarities and differences. Are they essentially the same circuit? Also, how would you describe the differences in sound? Not asking which is "better" just what the flavors are.

 

[Zen Mod]

B1 is having no voltage gain


B1K is practically B1 cascaded with small tube ( adding some voltage gain and toobish flavor ) cascaded with another buffer from B1 ( to ensure low output impedance)


so that's it ........ no more, but certainly no less than it was intended ......... making many Greedy Boy having wider Green while listening the music

 

[A Jedi]

Thanks ZM!

 

[Hikari1]

Also, I would add that other than the gain situation they don’t sound remotely alike at all. Probably as far apart as you can get. They really don’t share anything sound-wise. It’s just the the jfet buffer is the same topology in both circuits.

 

[A Jedi]

they don’t sound remotely alike at all. Probably as far apart as you can get. They really don’t share anything sound-wise.

Could you expound on that bit? I prefer a more neutral/technical sound signature rather than a colored/musical sound. I assume B1 is the former and Korg is the latter?