10 Watt Single End, JFET input - Lateral N-MOSFET output

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hi

Daniel Petrov from Sofia part of Bulgaria
is know at this forum widowmaker - profile
for his Death of Gainclone - DoGC amplifier
DoGC uses a clever and unusual output idea.
See separate topic, with discussion to try figure out how that one works ...


Today, I found another of his creations.
In a Bulgarian forum Daniel started a topic 2007-03-27 ( 27th of March )
Link:
Еднотактен клас А с полеваци

It is a 10 Watt Single End, JFET input - Lateral N-MOSFET output amplifier.
As can be seen in my attached schematic
it features very good, but still not hard-to-find transistors:

- 2SK389BL .... hifi low noise jfet for input - paralleled for 12 mA in first stage

- TL431, BC550C, BC639 for good Output Class A bias control and PSRR (supply insensitivity)

- Two 2SK1529 Lateral MOSFET for Output Stage

- No global feedback from output to input stage

-------------------------------------------------------------------------------------

2SK1529 is a Toshiba Lateral MOS of same series as 2SK1058.
But with a bit higher power:
- 2SK1058, rated 07A, 100Watt
- 2SK1529, rated 10A, 120 Watt
See amplabs.com POWER MOSFET data: http://ampslab.com/components_powermos.htm


Here below is is the attachment of this nice
- True Class A
- Single END
- ZERO global Feedback
- Toshiba Lateral MOSFET output
- 10 Watt
- Easy to build Power Amplifier
- Separated input-output power supply
- CLC filtered supply, a la Nelson Pass



Regards
lineup
:)

-------------------------------------------------------------------------
PS. widowmaker, hope you do not mind I post this
and copy your schematic into www.diyaudio.com forum here
... Me and many other have to brush up our bulgarian language .. a bit ;)
 

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And why only 10w outout but a 250vA Transformer, seems like a Big waste of power even for Class A....Seems like it might be a good space heater......

I"m no expert but it seems a few Changes to the design would probably greatly increase the output power, Like a Bipolar Medpower stage before the Output stage would actually give the Mosfets a good signal to drive the output stage, which is Probably why it is only 10w output and such a big Xformer......

I just finnished building a 30w Guitar amp (into 4 ohm or 18w into 8 ohms) and it uses a simple Opamp to drive a complemtry Pair of Small signal devices (BC550C/560C) which drive a Tip41/42 Pair of 6A devices and only uses a 50vA Transformer, and NO Output Caps, There shouldn"t be any output caps if useing a Dual Polarity PSU, Unless there is a Huge DC Offset, In which case the design should be looked at again as to eliminate any DC offset....

it seems Like a Pretty flawed design even for a space heater...But what the hell do I know.....


:D
 
Lineup is absolutely right. This Daniel Petrov is very clever.

The answer to the criticisms lies in the fundamental law of physics; loosely explained, more of this means less of that.

If you want highest possible sound quality, Class A is generally the way to go. There are exceptions, but it sounds pretty damn good. Petrov's design is economical, but looks old fashioned, and is inefficient electrically. But before commenting on these all too obvious flaws, it's a great idea to build it - there is sufficient information there although the choke size is not specified - try 1H for the jfet supply and 25mH for the output supply.

I think once you have heard this, even with a dc blocking cap on the output, you will smile, click your fingers and wonder why you'd not given it a try years before.....

How do I know? I built something very like this (my own design, also with an electro at the output) about 12 years ago and it remains my benchmark. Nothing I've done since manages quite to pip it.

Cheers,

Hugh
 
Leolabs said:
Why still output coupling caps????
AKSA said:
Lineup is absolutely right. This Daniel Petrov is very clever.

--------

How do I know? I built something very like this (my own design, also with an electro at the output) about 12 years ago and it remains my benchmark. Nothing I've done since manages quite to pip it.

Cheers,

Hugh


Thanks Leolabs Minion & AKSA.

1. Leolabs:

if you have only single supply 25V and output is at 12.5V something
I would NOT recommend attach speaker direct. ( will give 12.5 VDc across terminals )
If you mean, 'why doesn't he use dual supply?'
Well, that wouldn't make sense if you are after SE, Single END performance, 'sound'.

We can experiment with different quality and values OUTPUT CAPS.
I might try, for 6 Ohm LSP-ers
2x2.200uF in parallell or parallell two 4.700uF.

It should be noted, that Good Standard Electrolyts ( for example low impedance version )
of today,
are very superior in quality, than what was available at the time back
when these SE Amplifiers, Class A or Not, were the main stream.


-------------

2. Minion:

You are not sure you understand or know why to 'use only 10 Watt max output'.

True, it is not impressive in compare to 50-100 Watt rated.
For a young DiscJockey to use at his Disco-club, 10 watt no.

But here is more about not overdo, do more than we actually really NEED.
Class A can get TOO HOT


For a small to normal livingroom and non-disco, non-rave, non-techno music,
Maybe even Jazz, Blues, Soul or why not some interesting Classical pieces.
YES !!!
10 Watt into a normal LOUDspeaker ... is almost too much.
Even in the peaks of songs.


About Nelson Pass,
an old designer, his 'kitchen-table' effort and his 'First Watt' project:
He is using lower powers, 10 Watt and less and often in Class A output.
Info:
http://www.firstwatt.com/



--------------------------------

3. AKSA
.... Quote: ...................................................................
Nothing I've done since manages quite to pip it.
Cheers,
Hugh

....................................................................................

AKSA. Thanks for popping in to my new topic.
I know you know, so no need to inform you about this amp.

Your words are for others to think a bit about.

To Try to disagree with
.. or try validity of them by a real life setup, maybe
.. and so maybe have to agree!

Because you have long time experience.
Much longer than I have, eventhough we are same old age.

Regarding The designer of this amplifier, widowmaker - Petrov,
and the amplifier it self:
.... it takes one, to know one


-----------------------------------------------------------------------------------

This means,
.. in order to make a fair judge in a subject
.. you should at least have good knowledge in this field, subject
.. otherwise, you would need to ask some questions
... to get to know more, before making statements and be sure of things

---------------------
Example:
if a Priest in some Church, without any special knowledge,
is asked about what he thinks of Farmer John Smith, his breed of PIGS
and if they would be good to buy, if going into Pigs- farming,
this Priest should NOT try to say anything else
than ( what is not said often enough, by supposed experts ):
- I really do not know.
- You have to ask somebody better informed!


A priest is an authority, like doctor.
But their expertise are very much restricted to the field of their profession.

A farmer would know farming better,
although he is not, in our society, regarded authority
.. still in his profession, farming .. He Is The Real Autority to ASK


Regards
lineup
:)
 
Yep, Hugh, I also burried the "electrolytics on the output sounds bad" myth with some simple mosfet hybrid heaphone amps... I am yet to match that quality of SOUND in a loudspeaker driving amp...


If memory serves right, then the lower the impendance of the load, the larger the cap's value needs to get, in order not to form a knee in the audiable range...

being a perpetual beginner it took me while to figure out that there can be DC (silent) as well as AC (audiable) on the same signal wire... once that much is known the remedies are multiple... but, I for one will not have a problem with a good cap on the output.


I am not saying go and put them where there is no need... but don't expect them to suck the same way they did in the seventies....
 
Mmm,

me no likey the iron core coils at 2.8 amps bias level and the SK389 in parallel mode currently looks like a bit of a waste.
(Minion's post made a jolly moment)

2SK1529 no same series as 2SK1058 !
Both have gate, drain and source in the horizontal plane but the
Hitachi 2SK1058 is grandchild of 2SK135 and Toshiba 2SK1529 is afterbirth of 2SK405.
Rds-on of the Toshiba is somewhat lower, 0.83 ohm, 1 Ohm for the Hitachi's.
Not exactly sure about my memory database, but there's an image inside of the Aurex 2SK405(+2SJ) in the 100 watt Bower &Wilkins MPA-1 monaurals.

Nice MOSFET pictures
 
Hi Lineup, Nordic,

This output coupling cap is interesting. What is often not realised is that speaker earth return current passes through filter caps on direct coupled amps with bipolar supplies, and that in this instance such currents must compete head on with charge pulses coming off the power supply rectifiers. This causes intermodulation, and particularly damages very low level signals which give the necessary spatial cues for good imaging.

A coupler does not suffer charge spikes, and if the supply is unipolar, the power supply caps pass earth return currents on one half cycle only. This does not completely eliminate the problem, but it does ameliorate it.

Another advantage of these coupling caps is the opportunity afforded to hot bias the tweeter/midrange cap on the crossover. You can connect these drivers direct to the output rail at a potential around half Vcc, and thus get the benefit of better, more linear operation for the mid and high frequencies. This is a huge advantage. Then the electrolytic coupler has only bass duties; and a quality electrolytic, with a polarising voltage across it, is actually extremely good sonically.

Cheers,

Hugh
 
AKSA said:
Hi Lineup, Nordic,

This output coupling cap is interesting. What is often not realised is that speaker earth return current passes through filter caps on direct coupled amps with bipolar supplies, and that in this instance such currents must compete head on with charge pulses coming off the power supply rectifiers. This causes intermodulation, and particularly damages very low level signals which give the necessary spatial cues for good imaging.

A coupler does not suffer charge spikes, and if the supply is unipolar, the power supply caps pass earth return currents on one half cycle only. This does not completely eliminate the problem, but it does ameliorate it.

Another advantage of these coupling caps is the opportunity afforded to hot bias the tweeter/midrange cap on the crossover. You can connect these drivers direct to the output rail at a potential around half Vcc, and thus get the benefit of better, more linear operation for the mid and high frequencies. This is a huge advantage. Then the electrolytic coupler has only bass duties; and a quality electrolytic, with a polarising voltage across it, is actually extremely good sonically.

Cheers,

Hugh


Yeah, hugh.
you added some more benefits to using output caps

.. and in fact most any sound system uses 'Output Caps'
.. the difference is that
they are normally not called 'output caps'

They are loudspeakers crossover input caps.
Especially for higher frequency speaker drivers.
To block unwanted frequencies, to enter wrong element, woofers/tweeters,
and to keep things as constant as possible, as seen from amplifier out


I repeat:
Modern capacitors, has got SUCH high quality, we should use them more often.
I mean electrolytics are not like them used to be, back in the 60-ies / 70-ies.
Big Caps are a very simple & REALLY GOOD solution, many times.

An easy alternative to complicated 'stired up' jumbo mumbo to try to keep DC-levels in control.
And after all this DC-Coupling-Phreak-Show, a real show off in Volt DC 0.001, millivolts,
they would use a Crossover full of capacitance... anyway :eek:
Thinking they are smart :D

Some things are stupid and has not much of logic in it,
but some things are :hot: more Twisted & more Stupid :hot: than other things....


in audio
lineup :)
 
lineup said:


thanks for constructive contribution, chap
welcome back with more intersting stuff
:)
you may not agree with me and AKSA here,
and this is alright - but you may be able to give better alternatives/suggestions
and tell us your opinion

/the topic starter


Audio regards lineup :)


Where did i not agree with AKSA?


You simply mentioned "SE Amplifiers, Class A or Not". Can you give examples of SE Amplifiers of the "Not Class A" type?

When exacly were they mainstream?
 
:xeye:

whatever, analog_sa ;)

I hope widowmaker comes by here!
.. I guess he havent seen this topic, yet
But he can explain this 10 Watt SE, Single End
more to you and to anyone else.

as I said, you are always welcome to post in my topics
I leave it all, the rest of it
In the Lap of The Gods
*** see notes
.


Muchos Regardas
lineup
...............................................................
Notes:
In the Lap of the Gods ( by Queen )

"In the Lap of the Gods" is,
according to F. Mercury himself,
the direct prelude to "Bohemian Rhapsody" and
the A Night at the Opera album in general


Wikipedia - Sheer Heart Attack by Queen
- including 'Killer Queen'
http://en.wikipedia.org/wiki/Sheer_Heart_Attack#In_the_Lap_of_the_Gods


in this post, in this context:
The Gods = Our Censors, Moderators
... most are good moderators
... some are good censors, (Putin would be interested, maybe)
... some are both, but call them selves board moderators
gladly, lately, I have found at www.diyaudio.com
that majority of forum moderators belong to group A:
.. true and only moderators = still infavour of the 'free words' & expression

You do not have to cut, remove or hideaway or even change my message,
but you may moderate
my tone
& my way to execise, make use of
my human rights to express myself


:)
Pink-Mouse ... You ARE a good moderator
... in The True sense of the concept of board 'moderation'

My highest Grade Re-Marks to you, my friend.

I couldnt have done this better myself ( I was once suggested for moderator here )
 
Let's make it a typo, reverend Lineup undoubtedly meant single rail designs.

Lineup,

all good and true about the improvement of lytics but do not exagerate, it's still an electrolytic capacitor.
Bypassing electrolytics with foil caps reduces a lot of their flaws, just as it did with older style lytic caps.
Some folks even gave Rubycon caps a try when they were still affordable and less known, and dumped them long before the forum era started.
Here are some uF's of obsolete stacked polystyrene (with non-magnetic leads), the standard combination with a few MKP/KP uF's to add to an electrolytic output cap, for some.
 

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Lets Be Friends inspite of Lineup

analog_sa said:

Further nonsense...
lineup said:

thanks for constructive contribution, chap
welcome back with more intersting stuff
:)
you may not agree with me and AKSA here,
and this is alright - but you may be able to give better alternatives/suggestions
and tell us your opinion

/the topic starter

Audio regards lineup :)

analog_sa said:


I like this amplifier very much.
Widowmaker may be absent as you've scared him off with your promotion :)

:xeye: Lets Be Friends despite of Lineup :xeye:


analog_sa

sorry for misunderstanding you, in this topic I started about a good amp
i got you wrong by your first line .. see above

I owe you an apology: So here you have it
Hope its alright .. and we can go on here at least being 'audio friends'
even if possibly not being real life friends.
Who knows ...

Besides, man
you are probably right in this statement:
... as you've scared him off with your promotion :)


See you
lineup
 
jacco vermeulen said:
Let's make it a typo, reverend Lineup undoubtedly meant single rail designs.

Lineup,

all good and true about the improvement of lytics but do not exagerate, it's still an electrolytic capacitor.
Bypassing electrolytics with foil caps reduces a lot of their flaws, just as it did with older style lytic caps.
Some folks even gave Rubycon caps a try when they were still affordable and less known, and dumped them long before the forum era started.
Here are some uF's of obsolete stacked polystyrene (with non-magnetic leads), the standard combination with a few MKP/KP uF's to add to an electrolytic output cap, for some.

are all those caps yours?
:bigeyes:
 
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