So if you have Jfets with a Idss of say 6.5mA for example, does that mean you will automatically read 65mV across R3 and R4?
If 8-10mA is recommended for passing through Q1 & Q2, shouldn't you be reading 80-100mV across R3 and R4?
Is it even possible to bias a Jfet with a Idss of 6.5mA to 8mA by lowering the source resistors below 10 ohms?
whenever you introduce resistor in Jfet's source , while prior to that - gate and source were on same voltage potential , result is less current then Idss of part
just take Jfet as small pentode ....... or read this , for instance Junction Field Effect Transistor or JFET Tutorial
just take Jfet as small pentode ....... or read this , for instance Junction Field Effect Transistor or JFET Tutorial
OK, I did read post 495. I'm not sure what you mean by "out to ground 170 ohm".
Are you referring to R12?
The resistors are all numbered in the schematic, why not just state which resistors you changed like R10 & R11 to 65 ohms, R13 to 200 ohms, etc.?
I assume your combination resulted in much lower gain?
Check this out -- Very nice writeup of a whole club who made the BA-3 FE their reference preamp.
https://sites.google.com/site/audiosocietyofminnesota/Home/diy-projects/pass-ba-3-preamplifier
https://sites.google.com/site/audiosocietyofminnesota/Home/diy-projects/pass-ba-3-preamplifier
Vince - I also placed the 47K resistor in the R2 position and it got rid of the stepped attenuator clicks & pops. Thanks for mentioning it!
I mentioned it. I thought i was going to have to get a new ladder pot, the thing was so noisy. But adding the resistors solved the problem.
Oh, sorry... I knew it was one of you guys... 🙂 🙂 🙂
It's a heck of a nice preamp stage. I would love to try it with a shunt regulator - that seems like the next logical step, but it really is fine as-is.
It's a heck of a nice preamp stage. I would love to try it with a shunt regulator - that seems like the next logical step, but it really is fine as-is.
Sounds like I am going to let 6L6 find out before I try the shunt reg. C'mon 6L6, we all got our BA-3s built now we need to tear them apart again!
Seriously, I have been looking at the Salas shunt:
http://www.diyaudio.com/forums/power-supplies/153484-using-hypnotize-general-shunt-reg-pcb.html
And the kubota:
Kubota Low Noise Regulator Full Blown Version Kit | eBay
And this shunt reg:
Low Impedance 500mA Class A Shunt Regulator Kit | eBay
But I just bought a Rega P5 so I'll probably play with that for a while till I get some motivation to work on the BA3 again.
you can take shunt reg as A class amplifier , while (any ) series reg is B classs amp
one of important things is that shunt reg is bidirectional in nature - it can sink current , same as giving it
take a look at
Cook Book ; if not much about general characteristics of shunt regs , something is written about operation of one
😎ZM
Think there would be less room for misunderstanding to say:
Shunt is first quality amp and series reg is second second (or lower) quality amp (in this application)…….
or have I misunderstood you?😀
Think there would be less room for misunderstanding to say:
Shunt is first quality amp and series reg is second second (or lower) quality amp (in this application)…….
or have I misunderstood you?😀
it depends of what you prefer 
I know I prefer A class amps
so , taking that in account ..... I chose speakers easy to drive , so no need for drekload of watts
I could drive mine with beefed ....... or tube WOT preamp 
I know I prefer A class amps
so , taking that in account ..... I chose speakers easy to drive , so no need for drekload of watts
I could drive mine with beefed
....... or tube WOT preamp
Class-A amps have all the power running all the time and release it to the speakers. Class-AB have to modulate the power from the PSU.
It's the same for Shunt regs vs. series regs.
(Yes, the descriptions of operation are paraphrase, but you get the idea...)
Sounds like you need to build a Pearl. 🙂 😀
It's the same for Shunt regs vs. series regs.
(Yes, the descriptions of operation are paraphrase, but you get the idea...)
Sounds like you need to build a Pearl. 🙂 😀
Last edited: