B1 Buffer Preamp

[KatieandDad]

Mine has got Obbligato PIO's and they are """" NICE """ Also using a Salas Shunt Reg.

 

[Earthloop]

Mine has got Obbligato PIO's and they are """" NICE """ Also using a Salas Shunt Reg.

Those things are HUGE! Scared to imagine how much they cost. Did you make much experiment with the input capacitor types?

 

[voxxonline]

Ok. Regarding Obbligatos. I like them (thanx to KatieandDad) but I think very worthwhile alternative is my MBGO 2 caps NOS from Russia.
I might reverse back to them after all...

 

[voxxonline]

Obligato PIO does not cost much.

 

[KatieandDad]

I seem to recall that the Obligattos were only about £9 each.

 

[KatieandDad]

Ok. Regarding Obbligatos. I like them (thanx to KatieandDad) but I think very worthwhile alternative is my MBGO 2 caps NOS from Russia.
I might reverse back to them after all...

You can use anything you like as long as you can make it fit. Although the Obligattos are HUGE they did fit.

 

[udailey]

Great bang for buck cap.

 

[sangeet2]

Dont´t know where I should post in this thread with my problem, so I try here.

As soon as I turn the volume down in my B1, also the high frequencies getting damped.
I have to say that in the first place I installed the transsitors wrong with 180 degree. Now I installed them correct but the problem remains

 

[KatieandDad]

Are you using Pass B1 or one of the derivatives ?

 

[sangeet2]

I am using a PCB which I found here
DIY Audio Projects Forum • Pass B1 buffer clone (be1) with layout - A weekend project.

 

[Itsmee]

What value is the pot? Is it before or after the B1.

 

[sangeet2]

I tried different pots from 10k to 50k. Its (of course) before

 

[Itsmee]

I installed the transistors wrong with 180 degree. Now I installed them correct but the problem remains

JFETs are symmetrical in construction so should have survived, but thats no guarantee.

Do you have access to an oscilloscope and signal generator to see if you have a bandwidth problem when the signal is attenuated.

 

[sangeet2]

Hmmm, I have my ears

Also I do have Pink Noise generator from Logic as software and some software scope

 

[sangeet2]

Any more suggestions what I can do about would be great

 

[KatieandDad]

Silly question but have you got the volume pot connected correctly.

 

[sangeet2]

Thanks for your input

Yes pot is correct connected. If I dont put the pot but only the 1k resistor I also have the high frequencies damped

 

[KatieandDad]

It does look as though you have managed to make a variable filter at the input to the B1. Try increasing the size of the input caps.

 

[sangeet2]

Hahah, you´re right.

 

[KatieandDad]

What was wrong ??