Yes.
I cannot directly answer the second question but I believe it will be self explanatory once you start. I built the BA-3 front end as a separate stand alone preamplifier with it's own PS section. I believe all is required is to hook up the signal in and outs and + and - power and away you go.
Came to think about this, if you use e.g. the BA-3 front end as a preamplifier and then the complete BA-3 (front end plus output stage) as a power amplifier, you could reduce this to an integrated amplifier by building the complete BA-3 with input selector and volume control in one box. The separate aproach only has a meaning if you prefer the power amplifier close to the loudspeakers.
I do remember that was somewhat confusing but I think I found the answer in one of 6L6's build guides. If you do not find it I will do some searching.
I built the power amplifier as a stand alone without any voltage gain much like how the F4 operates. Like the F4 it depends on a preamplifier for the voltage gain. I actually prefer the sound better using a tube preamplifier rather than the BA-3 preamplifier, this is with horns mind you.
My error writing before thinking. And checking the BA-3. Conceptually though, a power amplifier with enough gain could be used as proposed - without a pre.
The purpose of the B1 or of course you could use some pots that Nelson does not approve of. I do not think using a passive with the 1V or so from a computer will achieve enough volume with every MP3 file even with my very efficient horns. With a CD player with it's higher output a passive would be fine. I think most of the Firstwatt clones will benefit using a pre with computer MP3 files. In the days of only CD players the B1 was a great option.
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I havent found the build guide,maybe sommeone knows this?
Maybe Mr Pass?
I`m in no hurry I am collecting stuff now,would be nice to know thow.
you have all answers on beginning of BA3 article
Papa didn't include those schematics for nuttin'
something as :
someone didn't do homework ?
I've been looking at a BA-1 frontend for a while as my current output stage ideas all have fairly low voltage gain... so I have questions about the bootstrapping of Q203: Does it work when combined with current source amps too or does it need a low output impedance voltage source output stage to function?
you need that bootstrap for obtaining proper voltage swing at node +D
that's your call which sort of OS you're going to use and , according to that , to connect or not nodes -D and S ......
however , I'm not fully getting what you mean by "current source amps" here ....... if anything can be called that , BA1 OS exactly can ......... even if I'm wrapping that in my head as function of entire amp topology , not just OS per se
btw. , you can also use BA3 OS (call it F4 if you like ) ...... which is classic source follower stage
that's your call which sort of OS you're going to use and , according to that , to connect or not nodes -D and S ......
however , I'm not fully getting what you mean by "current source amps" here ....... if anything can be called that , BA1 OS exactly can ......... even if I'm wrapping that in my head as function of entire amp topology , not just OS per se
btw. , you can also use BA3 OS (call it F4 if you like ) ...... which is classic source follower stage
Yes, the idea is to connect +D to the input of the output stage but to have a common source one instead of common drain. And then not add any feedback other than degeneration keeping the output impedance high at 100 ohm or more.
And lastly, if I've understood correctly the bootstrapping itself is kind of feedback but my hope was that it will not impact on the output impedance of the amp in any significant way. In that case it might be better for me to swap the bootstrap for a normal CCS. While this large voltage swing is nice my output stage will have some gain so I could get away with less swing on the front end.
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It has been awhile since I built this amp but without studying the article again I believe adding the FE + OS stage is the same as the BA-2 build guide presented here.
BA-3 Amplifier illustrated build guide
Stack the FE on top of the OS board per diagram and connection becomes easy. Excellent amp, one of my favorite FW builds.
BA-3 Amplifier illustrated build guide
Stack the FE on top of the OS board per diagram and connection becomes easy. Excellent amp, one of my favorite FW builds.