I foumd this amplifier in the net, called Gorilla - diyAudio
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Old 21st February 2006, 09:49 AM   #1
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Default I foumd this amplifier in the net, called Gorilla

I am showing as someone may be interested to construct it.

Also it has a lot of things to upgrade...there's a lot of parts values that may be changed, also transistors...well...there's a lot of room to updates and upgrades.

May be interesting to tweak.

C11 may be something between 5 to 15 picofarads.

C9 as 600 picofarads is a scandall

C2 is ridiculous!

C12 and C7....oh!...this value is a shame!

C13 may be 100 to 330 picofarads

There's no rail resistors, no rail condensers, and the designer forgot the output coil over the resistor.... also zobel is not there...well...this is something interesting to fix all those things and others.

May be interesting to construct the way it is shown, to listen, and them to fix those wrong things to compare.

Oh man!...will be enormous difference.

I do not know if it is good or bad, as i did not construct it.

But i like bootstrapped designs, also those NPNs in the output....also the diodes in the place of Vbe multiplier.

Enjoy guys.

regards,

Carlos
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Old 21st February 2006, 10:10 AM   #2
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Carlos
I don't think it is any good
first, it will have high offset and uncontrolled high bias
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Old 21st February 2006, 10:42 AM   #3
Eva is offline Eva  Spain
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This circuit has several serious flaws.

- It includes a bass-boost network (R23, C4) that may be undesirable.
- There is no way to control bias (component Vbe tolerances will do it randomly for you).
- The input LTP is biased with only 250uA or so, thus its current swing will be quite high in proportion to bias.
- The VAS is driven from the LTP in an awful way since it relies in VAS transistor hFE for input LTP current balancing (half of the LTP current goes to the base of the VAS and half through the 22K resistor, not considering diode leakage).

It may sound funny, though. You may even find a lot of people liking it
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Old 21st February 2006, 11:05 AM   #4
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Default Ahahaha!...a lot of people may like it!

Yes, it is possible, and there are many guys that love to fix those things, reason why a post it.

Those ones will spend a lot of time, and will make it nice.

There are obvious problems, but the circuit has enormous potential....to be modified.

Thank you Poznan, to let us know what you think about it.

regards,.....OH!...FOUMD WAS TERRIBLE!

Carlos
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Old 21st February 2006, 11:18 AM   #5
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I think you mix some things up.
Poznan is the place I live in.

Call me Adam


cheers and kind regards
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Old 21st February 2006, 11:24 AM   #6
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this guy is my namesake
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Old 21st February 2006, 11:25 AM   #7
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Pous nao, Carlos!
(spelling?)
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Old 21st February 2006, 12:51 PM   #8
lineup is offline lineup  Sweden
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Quote:
Originally posted by Eva
This circuit has several serious flaws.
.........
- The input LTP is biased with only 250uA or so, thus its current swing will be quite high in proportion to bias.
.........
Yes, this amplifier, I should NOT build, like it is.
It is supposed to give ------- 120 Watt -------

For this it has several serious defects.



I will here only comment the input stage.

Current source, ~250uA.
This gives, if input diff is balanced, is ONLY 0.125 mA in each transistor.
If it is NOT balanced, this is a non desired thing.


Myself, I prefer VERY much current in input.
I do not mind a bit of pure noise in amplifier.

If this can help to make amp to having less distortions of other type.

Input stage with good drive capacity, (at least 2.5mA, preferably 5-6mA in each),
and you start off at a high level.

You might even be able to have 1 stage less of amplification later (1T instead of 2T in VAS for example)
or get a better linearity in following stages.

5mA compared to 0.125mA is 40 times!!!!!!!!


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Old 21st February 2006, 12:57 PM   #9
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Personally speaking, i rather see Carlos destroy garbage as this instead of precious parts.

Gdansk is much nicer.
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Old 21st February 2006, 03:45 PM   #10
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Default I always perceived and readed you as "Pois não"...something from Portuguese, the

Portugal Portuguese...that has some difference, but is the ancient language and our respectable reference.

Pois não....seems "Beeing this way, the answer is NO"... the idea was..... "Can i say no to you?".... or a question in the place of an answer....strange those things..... i think it is very hard to learn Portuguese, as sometimes it is very strange.

Can be used as answer as some question alike:

- Can i talk with you?

The answer is that one....pois não!

I always did not apreciated those words...of course you have nothing about that....it is because has no sense, not used here in Brasil anymore....we use, now a days "Esteja à vontade"....means, stays relaxed and confortable, or at your will.

Pois não always sounded to me as something wrong...this way i always perceived this name in your threads.

Darkferinz is the name....glad to meet you Sir!

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

Hey Vermeulen....schhhh!..our secret!, do not tell people.

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

The intention is to show the schematic guys, as i do not remember if i could see it in the past, if i assembled or not, and has room to modifications, and there are many guys that cannot do nothing without modify.
.................................................. .................................................. .....

I think we are starting to be old Jacco....a famous band was in Brazil...i was shocked how they turn old....my God!

regards,

Carlos
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