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Old 14th August 2011, 07:16 PM   #211
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Quote:
Originally Posted by wahab View Post
Either linearity or OLG or both have to be improved for better perfs,
but in all cases , this is possible only with additionnal components...
Agree but to find the best sounding and good (not perfect) measuring performance from these parts count is a challange. We already have two very good sounding versions, mine with BIGBT outputs and Nico's with mosfet outputs. We maybe already reached to the finish line but nevertheles still all possibilities not checked yet. If you have limitation with parts count, their values makes even more importance.

Last edited by Lazy Cat; 14th August 2011 at 07:20 PM.
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Old 14th August 2011, 07:19 PM   #212
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I think the nice thing with laterals is that they act like constant current sources not much different from JFets. When used as a simple ( or double or triple that is ) EF i would prefer bipolars.
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Old 14th August 2011, 07:32 PM   #213
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Yes, but that kind of triple complex output stage we don't need here.

Harmonic distortion distribution-profile plot is acceptable, with Nico's version we are below 0,1% THD, output impedance is also well below 0,2 ohm, sound is nice, so the only thing left to us is to push boundary a little bit further if that's possible within proposed limitation.
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Old 14th August 2011, 07:37 PM   #214
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So Nico build the circuit post 141 ?
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Old 14th August 2011, 07:44 PM   #215
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Yes, and he reported in his last post:

Quote:
Originally Posted by Nico Ras View Post
I have completed the L-MOSFET with drivers. It sounds really good, clean, open and dynamic. It is stable and can operate into dubious loads. Again my compliment Lazy Cat it is a job well done.

Regards

Nico
As I know no changes he made to SCH from post #141, PCB post #158, it works.

I will soon prepare a sch of what I am listening here.
Attached Files
File Type: pdf LAZY CAT-NICO RAS AMPL[1].pdf (85.2 KB, 698 views)
File Type: pdf Lazy Cat Refined R01[1].pdf (42.2 KB, 590 views)

Last edited by Lazy Cat; 14th August 2011 at 07:49 PM.
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Old 14th August 2011, 07:56 PM   #216
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by wahab View Post
A good option would be to simply implement a double EF
as output stage , reducing THD efficently , as displayed
in the following graph.

IQ is about 0.42A in both cases.
I do like this Lazycat-Wahab option and I think it retains the original design philosophy. I don't have any MOSFETs in my junk box, only power BJTs. I also like a triple output with CFP drivers - I used it before in my TGM3 amplifier and it gave me the best sound from a Class AB so far in my experiments. The CFP driver provides very good low impedance drive to the output and protects the VAS from non-linear output drive. It was necessary in my case to add a small compensation capacitor to the -ve side CFP pair for stability - as is often the case; but it can be a small value - which is just as well because otherwise people say it robs magic from the sound. My TGM3 also used current feedback to the input, but it was asymmetrical and suffers from temperature shift of dc offset as well as turn-on blubs - I think the symmetrical current feedback front end may fix this ?
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Old 14th August 2011, 08:36 PM   #217
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Exclamation SSA BIGBT version

I am listening currently SSA of this sch.

This is simply turned into proposed limit of max. 8 transistors just by an exchange of BIGBT with mosfet driver/BJT output.
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File Type: jpg SSA BIGBT.jpg (318.2 KB, 1747 views)
File Type: jpg DSC00012.JPG (402.1 KB, 1664 views)

Last edited by Lazy Cat; 14th August 2011 at 08:57 PM.
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Old 14th August 2011, 08:58 PM   #218
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I like that one a lot. How does it sound ?
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Old 14th August 2011, 09:04 PM   #219
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Smile SSA sound

Just like I said in post #189:

Quote:
Originally Posted by Lazy Cat View Post
Thanks. Yes, yes, ... the sound from this simple schematic is only what it matters. It is so neutral, transparent, dynamic, easy flowing, like there is nothing in between source and the speaker, wire with the gain. Enjoy Nico!
What can I say more.
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Old 14th August 2011, 09:15 PM   #220
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Quote:
Originally Posted by Bigun View Post
My TGM3 also used current feedback to the input, but it was asymmetrical and suffers from temperature shift of dc offset as well as turn-on blubs - I think the symmetrical current feedback front end may fix this ?
Yes, please try the symmetrical current feedback front end and please don't forget to report.
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