Burning Amp BA-3

[Zen Mod]

huh

which version - I mean exact schm and what voltage(s) ?

symptomatically - V in VA is ...... ahem , voltage

 

[Ryssen]

P-BAC-S4V20 - Burning Amplifier Complementary Bias and Output Set for the BA-2 & BA-3 (Requires a gain stage; Makes 2 channels; Rev 2.0) - Boards

 

[noSmoking]

Hi Ryssen,
I think I have this figured out close,Anyone wish to jump in do so!
You got 2 channels so 2x6 transistors= 12 and 600va divided by 12= 41.666666 Lets call it 42VA to keep it simple per device,so if you use power rails at 42 vdc you can get close to 1 amp per transistor,half that to 21Vdc you could get close to 2 amps and so forth,it in actuality will be less due to losses,ect.if you read PAPA Nelson article on the BA-3 he states how to get more with different setups of source resistors,a good read ! I hope I have been helpful!

 

[Ryssen]

.if you read PAPA Nelson article on the BA-3 he states how to get more with different setups of source resistors,a good read !

Where can I read that article?

 

[flg]

Burning Amplifier BA-3 - diyAudio

 

[noSmoking]

there are many good articles here and all 3 ba articles should be read and digested ,lol,
FIRST WATT look under articles

 

[Zen Mod]

oopsie

good image link

 

[neoinc]

My first impression about BA-3 would be that it creates a very spacious and airy listening experience. As i hear it now, I would think that folks who love listening to music that reveals or shows off the recording venue. This is very preliminary as I have not even given the caps a chance to break in. I will be trying many different configurations with this setup, including different caps, output transistors, and even thermal insulation. So as not to bog this thread, I will only reveal listening stuff here. To hear more about other permutations, check out this thread.

http://www.diyaudio.com/forums/pass-labs/201186-humble-beginnings-d-3.html

As I couldn't wait to hear a BA3 with a F4, I decided to test it out on my F5. I ran the source through the B1 -> BA3 -> F5. And volia! I could hear music. And as Buzzforb described, the soundstage increase and the music is airy with good strong bass. I couldn't believe I could hear such a big difference. Thanks you Papa.

 

[buzzforb]

As I couldn't wait to hear a BA3 with a F4, I decided to test it out on my F5. I ran the source through the B1 -> BA3 -> F5. And volia! I could hear music. And as Buzzforb described, the soundstage increase and the music is airy with good strong bass. I couldn't believe I could hear such a big difference. Thanks you Papa.

 

[Botte]

single endid bias

Has anyone tried adding a current source to one side of the follower output, Nelson talks about this in the "Leaving Class A" article? I'm thinking about giving this a try and wonder if anyone has any experience with it.

Thanks,

 

[Zen Mod]

if Pa sez it's worth ......

 

[buzzforb]

I guess properimplementation entails trimming the distortion using P3 to minimum. By adding CS like in Leaving Class A article, you get some of that firstwatt sweetness back in form of second harmonics, but still benefit from lower overall distortion.

 

[Ryssen]

P-SSSDP-2V20 - Soft Start Board & Speaker Turn-On Delay and DC Protector Board (set of 2 boards) - Boards

I guess its built for 110v AC?Can it be used for 220v,I guess it is easy to use a f.e.x a 24v trafo?

 

[JojoD818]

I guess its built for 110v AC?Can it be used for 220v,I guess it is easy to use a f.e.x a 24v trafo?

It can be used in countries with 100V, 110V, 220V, 240V etc without the need to use any trafo. There are some good info in the build guide also.

Thanks

 

[noSmoking]

Has anyone tried adding a current source to one side of the follower output, Nelson talks about this in the "Leaving Class A" article? I'm thinking about giving this a try and wonder if anyone has any experience with it.

Thanks,

Hi Botte,
No I haven't butt If you do give it a try I would like to hear your results,
and if probability prevails ..papa said it will work,lol, I am going to to read that article and see how it works! GOOD LUCK!

 

[nkdk]

Hi
I got a little trouble with biasing the ba3, i use thosiba fets.
Q1= 2sk170
Q2=sj74
Q3=2sj313
Q4=2sk2013
Dc. rails 25.2 Vdc Dc volts over r10-r11 max 0,4 Vdc.
everything is after the bom. so what is wrong?
Nkdk

 

[tinitus]

I got a little trouble with biasing the ba3

Dc volts over r10-r11 max 0,4 Vdc.

BA3 frontend schematic says 1V

wrong value on bias pot

 

[BDP]

Hi
I got a little trouble with biasing the ba3, i use thosiba fets.
Q1= 2sk170
Q2=sj74
Q3=2sj313
Q4=2sk2013
Dc. rails 25.2 Vdc Dc volts over r10-r11 max 0,4 Vdc.
everything is after the bom. so what is wrong?
Nkdk

There are variations in parts that you have to account for. It was talked about that you might have to increase variable resistor P1 P2 in order to get the voltage up to turn on Q3,Q4 if their Vgs is higher than normal. The other way is to choose a higher Idss for the input devices.
What's the voltage across the 600 Ohm drain resistance, assuming you have adjusted for maximum.

 

[tinitus]

.......you might have to increase variable resistor P1 P2........

with higher value bias pot, which 'side' is increased ?
supply side, or jfet side ?
reason I ask, you could try with a series resistor

but by using a slightly too big bias pot, it should be easy to lower its value with paralel resistor
btw, why isnt there any this time ?
isnt there usually one ?
for whatever reason
the above, or in case the pot fails ?
maybe it also takes some of the 'load' off the pot, but I dont know

 

[nkdk]

Hi
Thx for the answers
I have swap p1-p2 too 1kΩ and the volts over R10-11 is 1,0 volts now, then this okay ,
there is running 45 ma , but how about Q1-2 there is only running 4 ma,is that a problem ??
600 Ω drain resistor? , there is no 600 Ω resistor only 10 Ω with a 100 Ω pot
Nkdk