Simple Killer Amp!

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#321
amplifierguru said:
Hi doggy,

Yes the inrush currents from a 500VA are likely a bit high for
4 x 3A diodes driving 14,100uF/14,100uF without some limiting R in series.
I use the power supplies with 160VA (monoblock) and 300VA (stereo)

Cheers,
Greg
Click to expand...

nice to see you back, amplifierguru

now try to be a good boy, so we do not have to miss you, no more
😀 😀
 
#324
Kuei Yang Wang said:

But I retain that the differential Amp's are troublesome.
Click to expand...

Sorry old chap...but your preferred 'current feedback' arrangement ALSO uses a differential amp. for application of feedback...

only difference is that with so-called 'current feedback', the feedback signal is applied directly to the emitter of the diff. amp., viz. the voltage fed back is unbuffered..
 
#328
Hi,
I suspect that the fuses are protecting the speaker from excessive DC after an output device has failed.

If I have surmised correctly, I would like the amp to shut itself off before taking out my drivers. For this reason I am thinking that faster is better.

Could the fuses be there to prevent progressive failure taking out further devices?

Or are they for short circuit protection?

There appears to be little else for protection than the usual Zeners on the Gates. This form of protection relies on very robust output devices and these IRFs probably fall into that category. Can anyone confirm?
 
#334
fab said:



Hi JojoD

This is what has been disclosed by Greg Ball :
http://www.diyaudio.com/forums/showthread.php?postid=736240#post736240

So this SKA schematics principle is public from Greg and this is diy here...
Click to expand...


Hi fab,

The schematics have no values in it? I have diy'd several amps out of schematics posted from this forum before (Leach, P3A, etc.), but thanks anyway.

From AndrewT's post, intellectual property may mean the circuit is not available online and so I may need to buy a kit or something if I want to build one.

Thanks
 
#335
lineup said:
Hello, amplifierguru

A question.
Is there any chance you will publish more details,
like components and values, on SKA Mk1
when a new version is released?

Nelson Pass is using this method with his First Watt series:
Each design is a different exploration into high quality at low power.
At the end of the sales cycle of new product, the schematics and technical details of each design
will be posted for the benefit of the "DIY" community.
Click to expand...
lineup said:
amplifierguru

can you post complete schematic of this amp

just want to check out, you haven't made some less good things
if so, we will help you improve
and this is good for you
Click to expand...

amplifierguru said:
Hi lineup,

Thanks for the offer
but I'll take my chances at present and keep the detail proprietary.
Maybe after the first 100 pairs I'll reconsider.
I trust you'll understand.

I still have to work out where I'm taking this.

Cheers,
Greg
Click to expand...

######################################

JojoD818 said:
Hi guys,
Could someone be kind enough to point me to the schematic of the SKA?
Click to expand...
JojoD818 said:

The schematics have no values in it? I have diy'd several amps out of schematics posted from this forum before (Leach, P3A, etc.), but thanks anyway.

From AndrewT's post, intellectual property may mean the circuit is not available online and so I may need to buy a kit or something if I want to build one.
Click to expand...

######################################

JojoD818


As you can see I asked this from amplifierguru, in January 2006 before he left diyaudio.

His answer to the great offering I gave him 😀
was that he may consider this in future:
Maybe after the first 100 pairs I'll reconsider.


Sorry to say, as demand for SKA has been so good, as I think it has,
I doubt very much
he will give away much more of the exact circuit of SKA.

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


But just we wait 1 year or 2
and somebody SKA owner may publish the full schematic here
when asking us for help to fix some problem with a SKA amp
or make some wanted custom modification redesign ....
😉

Any amplifier secret always will be public knowledge
sooner or later, one way or another
at the audio internet community.
Sometimes we have to trust our Russian or Chinese friends
to give us good information.
Through the fully open backside door.

That's how it is ... in reality.
Be it good or bad.
And whether we like it or not, does not matter the tiniest bit.
Or does it?


lineup
Lineup Audio Amplifiers
http://lineup.awardspace.com/

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

PS.
I have several interesting unique amplifier circuit topology solutions
that I have never seen anywhere else.
And as they work extremely well and effectively
compared to common ways used, at last in my Multisim SPICE testings,
I will also wait a bit before giving it away for free.
There is always someones out there,
ready to copy and put their own brand to a good idea
and make every single buck they can out of it.
DS.
 
#336
Hi lineup,

I see that you have already asked for the schematics a long time ago. Anyway, I fully respect the idea of Intellectual Property and so shall abide by the designer's wishes. Like you said, maybe I'll just have to wait for about 3 or 5 years. 😀

However, it has also been my hobby to diy my own boards out of the schematics our friends post here. Unfortunately, this may not presently happen for the SKA and so I'll just look for other interesting amp to satisfy my diy hungry fingers. 😀

Cheers
 
#338
okay
JojoD818

powerbecker, Heinz is a very clever amplifier guy.

In his Post #230 in this topic
he attached a PDF Circuit, he called SKA Guess.

It is full design with component values and is based on published simplified schematic
and what little additional info / details that amplifierguru has told in his many posts.


Below is amplifierguru comment to this powerbecker PDF circuit:
Quite close!
Now we should not blindly trust when amplifierguru tells this.
Even if a circuit suggestion would be very far from SKA
he might say like this anyway ....

Links:
😎 PDF SKA Guess Amplifier - in PDF attachment

😎 powerbecker Post #230 and and amplifierguru reply

amplifierguru said:
Hi Heinz,
Excellent sleuthing there. Quite close !

However I'm using BC546/56C's for low bias current and current sources are 1mA.
I have a slightly more complex current source arrangement as Tcomp is too severe as your cct stands ( about 1/2 is required).


Q12 and Q13 loads should be joined and floated from ground,
giving a push/pull complementary EF.
That may help the PSRR sim.

But you're so close I can't comment further I need some proprietary detail.
By the way, your sim will burn test resistors with a switch on surge.
Mine doesn't.

I'm happy with Vgs matching of these MOSFETs as they have an inherent source R with a +ve tempco.

Glad you like it.

Cheers,
Greg
Click to expand...


lineup
 
#339
AKSA said:
Jojo,

Try Michael Bittner's Symasym. It is an excellent amp and with experienced layout will well reward you......

Cheers,

Hugh
Click to expand...

Hi Hugh,

Thanks for the heads up!

Best Regards,
JojoD




@lineup,

reading between the lines in your quoted post is exactly what's pointing me away from the SKA. 🙁

nonetheless, I believe that there are other exciting projects out there just waiting for me. 😀 Mr. Dean already has a suggestion, see what I mean? 😎


Cheers
 
#340
JojoD818 said:
@lineup,

reading between the lines in your quoted post is exactly what's pointing me away from the SKA. 🙁

nonetheless, I believe that there are other exciting projects out there just waiting for me. 😀
Mr. Dean already has a suggestion, see what I mean? 😎
Click to expand...

Good advice from Hugh AKSA Dean.
There are several other interesting diyaudio amps to try.
Many of them have no standard PCB layout, yet.

SymaSym is a great amplifier project.
Still there is development, refinement going on and may come another new version after some time.
It has got everything that makes a very good amplifier project.
MikeB and 'his guys' in the SymaSym topic can give 100% perfect support
when building a SymaSym.


Good luck, JojoD818
whatever next project you will build.
You will make yourself a great new amp
and I know it will not be the first time you do it.


Regards
lineup
 
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