BA3: Complementary vs. Single Ended

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Not the speaker end, that's just the amps output. You can have a single ended amp, or a push pull amp. This has nothing to do with whether or not amp is balanced.

If you have a balanced preamp, it is nice to have a balanced power amp to go with it. If you preamp isn't balanced there is still a way to use the unbalanced (single ended) preamp with the balanced power amp.

A single ended power amp, like a 300b tube amp, or an Aleph pass amp, has nothing to do with it being balanced or not.

To add to the confusion, one with a balance preamp might like to have a single ended output on it in order to use it with a power amp that isn't balanced.

Maybe read up on the BA3 power amp, study 6l6's build guide. Once you see it clearly, read up on the balanced BA3 (BBA3). Assuming both are "complementary" or push pull, the difference will be clear. The other "single ended" version of BA3 has nothing to do g to do with whether or not the amp is balanced or not.

Balanced amp and pre amp will not be connected together with RCA plugs, but 3 conductor plugs.

Look also at 6l6's Aleph J build guide. Here, we have a single ended out put Aleph amp, but you will notice he includes both RCA inputs and the 3 conductor inputs, while AlephJ isn't balanced, you can still use a balanced pre with it. Again, the fact that the Aleph J is single ended, (like a single ended 300b amp) has nothing to do with whether or not it is balanced, which it isn't.

Separate the terms single ended outputs, from push pull outputs in amplifiers, from whether or not the particular amp is balanced. Output here refers to the output stage, not whether or not the amp is balanced or not.

Russellc


Hey Russellc, Just reread your post, and this time it makes much more sense after having read a bunch more on the topic. Thanks.
 
For F4, also consider Zenmods Pumpkin-Shunty pre amp. It can be used single ended or balanced and has plenty of drive for regular F4, or 2 balanced mono block F4 amps. Big build guide available. It is one of my many "almost done" projects.

Russellc


Awesome, will read up on the Pumpkin Shunty for sure. Know anything more about the empasse tube preamp that 6L6 mentioned in his F4 build guide? Thanks again for your help.
 
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Awesome, will read up on the Pumpkin Shunty for sure. Know anything more about the empasse tube preamp that 6L6 mentioned in his F4 build guide? Thanks again for your help.

I know if 6L6 says it is good, then it is good! Not personally however. I used to be an all tube person, but Mr Pass has brought me over to the land of Jfet. Sold most all my tube stuff and collection of NOS tubes.

Russellc
 
more novice questions

Maybe both - input and output.

BA3B pre - balanced input and balanced output, can be used as:
balanced input and balanced output
balanced input and unbalanced output
unbalanced input and balanced output
unbalanced input and unbalanced output (don't see the point of this, may as well use BA3 instead)

Thanks for all the responses, I'm in a similar situation as OP. Really interested in making balanced BA3 front end as I have a good DAC/preamp that only uses half its hardware via single ended output (NOS11).

1) I'm fairly sure each complementary bias/output board pair will only take half of the balanced signal, 2 output boards per channel, one for each polarity. Just like SE burning amp 1 or 3 output expect transistor orientation. please confirm.

An externally hosted image should be here but it was not working when we last tested it.


I need need 1 stereo amp, it might be possible to pack 4 total output boards in the shop's largest chassis if I set the bias low enough and/or reduced Fet count. less then ideal solution

2) how does ba3b do balanced input and single ended output? or is there something about preamp build that lets it do this?

Basically I need a front end that accepts balanced input from my pre, but i don't want to scale up to 'double' output stages like the above schematic or the F5 balanced variations. What i really need is the BA-1 front end, but i cant find matched lsJ74 outside of questionable e-bay sellers.

3) would a person need specially matched fets for BA3b? clearly you need the N and P pairs matched, but do you also need decent matching between the pairs (matching + and - sides)?
 
Look at the BA-2 Simplified drawing. Burning Amplifier BA-2 - diyAudio
The 2 jfet's plus the CSS form a Long tail pair.
This is one of the common ways to convert balanced to single ended.

This is the BA-1 front end, the one I know fits my needs the best. I'm pretty sure the way forward for me is just waiting for the next round of matched j74 to become available.

I know I could probably use some kind of superfluous transformer summing stage and that would really open up my options, but like i said, superfluous.
 
I believe you got it right

What i really do not understand is the fact that the gates of the lower output stages pulled all the way to the ground; didn't they behave in that position as simple constant current sources? ...

And most puzzling ; this being the no feedback single ended solution I would imagine as the most adopted solution as opposite to the push pull that handles the signal only partially ... and reaching the question: Why this Ba3SE is so unpopular ? So much so nobody ever built it?

Edit:
And finaly Zen ; thanks for answering :)
 
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Several have built the single ended version. Member wdecho comes to mind. Myself, I like 6l6 in his BA3 build thread did the complementary version. One of my favorite amps.

Russellc

Thanks Russel ; i am gathering materials for both single and complementary output stages ; I find single ended as the simplest and most natural solution one can use in amplifying for the simple reason the wave is fully reproduced by a single transistor(this case the load is distributed over 3).

Hence my searching for someone who did a successful build in order to ***** if the transformer supply is the same to a complementary version and to have person(s) to direct potential questions at build time. (my imediate concern is transformer power and capacitor sizes)
 
I did build the Single Ended BA3; 6 deep output stage biased at 4.5 Amps.
2x22.5 Volts. 3x 47 mF per rail, 1200 VA transformer (see pic)

Very stable, sounds great and 55 C on top of fins.
Switchable to run 2x25 W or bridged/balanced 100 W mono block
(using BBA3 FE)

/Mats
 

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Thanks Jeff.

Well, perhaps not the most beautiful way, but allowed me to spread the heat evenly (and there is lots of heat) over the full ~20 inches of the sink.

Using tightly stretched 1.5 mm2 solid copper wire (approx AWG 16) as a "drain line" and "source line" and a thinner "gate line" from where a total of 24 gate resistors are dropped to each IRFP240.
 
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Dunno mate, looks a heck of a lot better than most of my efforts do!

Nice work.
Thanks Jeff.

Well, perhaps not the most beautiful way, but allowed me to spread the heat evenly (and there is lots of heat) over the full ~20 inches of the sink.

Using tightly stretched 1.5 mm2 solid copper wire (approx AWG 16) as a "drain line" and "source line" and a thinner "gate line" from where a total of 24 gate resistors are dropped to each IRFP240.
 
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