Burning Amplifier BA-2

[Vix]

Hi,
It's another candy in there
Looks like we have somewhat more complex version of BoZ inside a BA-2 front end. And it can be used as an (almost*) stand alone preamp in case that you want more gain, or, perhaps you built a SEWA amp some time ago and need a preamp...

*"Almost" because it will need a buffer on its front end (if you want to place a volume pot on the front).

[Zen Mod]

Originally Posted by Vix

Hi,
It's another candy in there
Looks like we have somewhat more complex version of BoZ inside a BA-2 front end. And it can be used as an (almost*) stand alone preamp in case that you want more gain, or, perhaps you built a SEWA amp some time ago and need a preamp...

*"Almost" because it will need a buffer on its front end (if you want to place a volume pot on the front).

if you look back at several Papa's articles - "Discrete OP for Dumb DIYas from Balkan" (read there - ZM & Vix) ,some of his first amps (A class , A75 - where bootstraping was used ) , then this FE is nothing new .

but - we agree that we are from Balkan ..... so for both of us - main thing is that Papa still use caps in signal path , and that I ( O Tempora , O Mores !) very cleverly recognized some time ago how he manage to use TL431 to bias those thingies ..... without caps in signal path .....

[chinsettawong]

I have just finished reading the article. Thank you Mr. Pass so much for your generous contribution.

Wachara C.

[Vix]

Originally Posted by Zen Mod

if you look back at several Papa's articles -
but - we agree that we are from Balkan ..... so for both of us - main thing is that Papa still use caps in signal path , and that I ( O Tempora , O Mores !) very cleverly recognized some time ago how he manage to use TL431 to bias those thingies ..... without caps in signal path .....

Well, we should get over it!!

p.s. I also miss that COOL icon...Now I gotta use this one, resurrected...

[Zero Cool]

Originally Posted by Zen Mod

re-read article few times .....

even if I didn't , I can bet that Papa explained that entire voltage swing is coming from front end .....

output stage is follower ........ not having voltage gain



blahblah

See i am missing some part here. I have re-read the article several times in fact.
what is the voltage swing at C203?

[yggdrasil]

The voltage swing at C203 is (almost) the same voltage swing you se at the output. Remember the output stage do not have any gain.

[AR2]

I have a complaint.
Nelson's articles are addictive. It was around 4:30 in the morning, I woke up for some reason, and found this article. I read it and I am ready to start soldering!

Now if we put some practical taught to it, Nelson should put together a book:
Class A Amplifiers for insomniacs.

[Zero Cool]

As i understand it. the Jfets are hard to get? is there a good source for these in the US?

[Vix]

Originally Posted by AR2

I have a complaint.
... It was around 4:30 in the morning, I woke up for some reason, and found this article. I read it and I am ready to start soldering!

While I will not ask you what was the exact reason you woke up at 4:30 AM, I hope that the article about the Beast amp with 1000 J-fets won't appear at that time. Not to mention the soldering!

[bakpaosiomay]

can we use match sj103 for the diferrential and 2sk246 for ccs?
maybe paraleling 2 of 2sj103?
its very hard to find 2sj74 in my country.