Never, because there will always be personal versions - which differ slightly. The blueprint is in place and will work, everything else is an iteration - from this perspective, a more definitive version will only emerge in a few years' time.
Before that, the 25W-Krill will probably be on the table.
If you like, you can work on a test setup in advance - my first PCB will follow the last schematic pretty much 1 to 1, with one or two assembly options.
Patience please
(or already get started independently)
greetings,
HBt.
😎
T6 need an emitter follower buffer or else the distorsion will be gigantic, we re talking a 20dB or so higher THD
and IMD with the current schematic, beside the IPS current is uselessly high wich mandate a uselessly high
compensation capacitor that increase distorsion
This topology shortcomings are well know at this point and one can design a much better sounding amp than
the Black Devil wich was a popular such design in the 70s.
For all those who can't make any sense of Wahab's interjection:
The German magazine ELRAD from Hanover -lower saxony- published an amplifier proposal by Mr. Georg Schwarz in issue 1 in 1988, where we find the BDV65 and BDV64 often mentioned by Wahab as a push-pull output stage in B mode. The circuit proposal is called "black devil" with the predicate "high-end transistor power amplifier" - the article is well worth reading, it demonstrates what is, or was, possible with ancient circuit technology.
Oh dear, I've just realized that you mean Beelzebub the little devil - Black Devil.
There's nothing wrong with him, he's just lovably evil - before the transformation!
HBt.
The German magazine ELRAD from Hanover -lower saxony- published an amplifier proposal by Mr. Georg Schwarz in issue 1 in 1988, where we find the BDV65 and BDV64 often mentioned by Wahab as a push-pull output stage in B mode. The circuit proposal is called "black devil" with the predicate "high-end transistor power amplifier" - the article is well worth reading, it demonstrates what is, or was, possible with ancient circuit technology.
Oh dear, I've just realized that you mean Beelzebub the little devil - Black Devil.
There's nothing wrong with him, he's just lovably evil - before the transformation!
HBt.
Good question, so that 25W are possible, i.e. +/-25Vdc.
I will leave the second part of the question to speculation - for the time being.
I hope this doesn't upset you - I'm in a bit of a hurry.
kindly,
HBt.
A final measurement will show how gigantic they will be and, above all, how extremely disturbing they will be.
0.0001%
20dB worse equal to 0.001% (or do you assume 1% to 10% ?)
I'm starting to itch to breathe life into Beelzebub - even before the Krill /please don't trigger me 🙄.
Bye,
HBt.
I refer to posting #1
THD
10kHz - 0,09%
1kHz - 0,01%
0,1kHz - 0,06%
with Load and 21,5Wrms
THD
10k - 0,05%
1k - 0,01%
0,1k - 0,06%
with Load and 5,33Wrms
all up to the 9th harmonic, and this is the very worst case with the boy, asymmetric in the FET's and really nasty with k2 when it gets down to business.
Beelzebub is not clean, but definitely not boring either.
#
Dear Wahab,
I would be happy to receive a concrete dimensioning from you - all my suggestions and ideas are open. Maybe even a drawing, a drawing is worth a thousand words.
Greetings,
HBt.
Psst
The Buffer has already been successfully launched by 'lineup' 😉.
THD
10kHz - 0,09%
1kHz - 0,01%
0,1kHz - 0,06%
with Load and 21,5Wrms
THD
10k - 0,05%
1k - 0,01%
0,1k - 0,06%
with Load and 5,33Wrms
all up to the 9th harmonic, and this is the very worst case with the boy, asymmetric in the FET's and really nasty with k2 when it gets down to business.
Beelzebub is not clean, but definitely not boring either.
#
Dear Wahab,
I would be happy to receive a concrete dimensioning from you - all my suggestions and ideas are open. Maybe even a drawing, a drawing is worth a thousand words.
Greetings,
HBt.
Psst
The Buffer has already been successfully launched by 'lineup' 😉.
I ll throw the thing in the simulator once i ve some time left, but a question, do you want to keep the IPS
current at about 2mA.?.
And when i say gigantic THD i mean something that is 0.03% at 1KHz, sure that class A help a lot to linearize
the OS but what is the point to dissipate something like 90W, like in the AlphaNirvana, while lower THD can
be achieved with a cautiously designed AB class amp even when using this Black Devil inspired topology.?.
Greetings as well.
current at about 2mA.?.
And when i say gigantic THD i mean something that is 0.03% at 1KHz, sure that class A help a lot to linearize
the OS but what is the point to dissipate something like 90W, like in the AlphaNirvana, while lower THD can
be achieved with a cautiously designed AB class amp even when using this Black Devil inspired topology.?.
Greetings as well.
Good observation.
Not necessarily, of course. But I don't want an LTP. However, the choice of BJTs is completely up to you.
You are absolutely right about that. For reasons of smell or technical reason, you and I are on the same wavelength anyway.
Do you know the nickname of Beelzebub? He's also known as ANK - alpha nirvana killer.
Of course, this is possible without any fuss.
The top priority must be a simple design with an acceptable minimum of components (the blueprint is available in this thread) that gives the DIY of Beelzebub diabolical pleasure.
HBt.
I tested with resistor to the rail and this does not do any change or improvement.
As you surely often experimented it the devil always hide in some details, and here it s in the current limiter.
If the load is too low and that the negative side saturate because of lack of output current then the recovery
will be awfull, to improve the thing a 470pF capacitor must be connected from base to collector of T5.
Even without saturation it is necessary because otherwise this transistor create a pole at high frequency,
i guess that in the AlphaNirvana this is also tamed by a random serie of lead capacitors wich in principle shouldnt
be necessary if the thing was well designed, wich in my opinion is not the case, that s not all to find a fancy name
to make an amplifier performing well.
Also, what is your pojected transformer s AC voltage.?.
In principle this kind of connection should help increasing the VAS input impedance and hence the input stage gain,
but here it s not of big effect because the VAS has low gain and low input impedance anyway, also the value of this resistance
set the input stage current since the feedback will set the voltage through this resistance at the necessary value to reach the VAS Vbe voltage.
I'll have to think again about an additional C_komp parallel to the base-emitter path of the T5. But its installation, should it actually be necessary (and that is not at all unlikely), can also be carried out on the object itself at any time without any problems.
Thanks Wahab for this reminder, let's not forget Beelzebub is an incredibly quick thought and also a reaction to the nice sounding Alpha Nirvana stuff - whose compensation scheme I (personally) find completely off the mark.
AC-Voltage? min. 2 * 18Vac!
And this is exactly what I intended.
Weird, maybe it's supposed to illustrate something very specific 🤔.
But nonetheless, our common Beelzebub can take steps towards a positive development. I have no objection to that.
kindly,
HBt.
